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CE Project: CE Bot [PART TWO]

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ANNOUNCEMENT: Celab.tk is no longer accessible. Please go directly to:

CE Bot (CE Lab Projects)

for the Project Website, thank you.

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Welcome to Part Two of CE Bot. We will continue the discussions regarding the CE Bot project in this thread.

For previous discussions, please refer to Part One: https://www.crazyengineers.com/forum/ce-labs/2312-ce-project-ce-bot.html

Introduction of CE R[sup]3[/sup]
CE R[sup]3[/sup](formerly CE Bot) is a project regarding the design and construction of a modular robotic system that can perform various research missions.

Its first mission is that of a semi-autonomous rover. It will consist of an array of sensors, mainly to detect it's surroundings and collect data for processing purposes. Data will be wirelessly transmitted to a host computer located a distance away. The design of rover will be modular to allow for interchangeable components and ease of future upgrades.

For more information on the CE Bot, please refer to the CE Lab website: CE Bot (CE Lab Projects)

Summary of previous discussions

Formulating objectives;
Discussion opens up for defining mission and roles for a robot. A laptop would be utilized as the pre-processing unit and robot controller. It is proposed that the mission will involve data collection and rescue, amongst others. A host computer will be used in the vicinity to act the main processor of data as well as external control. To allow the robot to cater with vast types of applications, the robot will be designed modularly.

Communications;

Discussion leads to methods for processing data and which wireless technology to use to transmit data. 802.11 is proposed.

Chassis/Locomotion;
Various chassis and locomotive options were discussed, such as tracked and wheeled. Some CAD designs have been uploaded for conceptualization of ideas.

Things to discuss in Part Two:
  • Further Robot Chassis Design
  • Sensors
  • Simulation software tests
  • Python tests
  • Wireless connectivity tests
  • Draft proposal for funding
---------------------------------
As of August 6th 2008, still needs updating. Will add more things soon.
KINETIC_JOULES
KINETIC_JOULES • Jul 11, 2008
Wow. . .a whole new thread! Yay!
Like I said, I'll get on those designs very soon. I will be gone later on today, Saturday, and Sunday, so no designs then. I leave at 4:00 PM my time, which is in 3 hours. Sorry I haven't come up with anything lately. . . I've got artists block. It sucks.
Take your time, Kinetic.

CEans, please do post your suggestions or comments in this thread. By posting here, you are part of the project already ๐Ÿ˜‰
gohm
gohm • Jul 12, 2008
Just a real quick note before I forget, as we were chatting about the pros & cons of battery vs. gas power supply, how to provide drive for the bot and solar cells to recharge or linking the brakes into alternators to provide electrical charge. Personally I think awd via chain or tracks is best due to simplicity, weight savings. dwd, direct wheel drive can also be achieved though would add to weight. I'll talk more about then later.
KINETIC_JOULES
KINETIC_JOULES • Jul 13, 2008
I'm back guys!
gohm
Just a real quick note before I forget, as we were chatting about the pros & cons of battery vs. gas power supply, how to provide drive for the bot and solar cells to recharge or linking the brakes into alternators to provide electrical charge. Personally I think awd via chain or tracks is best due to simplicity, weight savings. dwd, direct wheel drive can also be achieved though would add to weight. I'll talk more about then later.
Thanks for that, gohm. Looking forward to see more details later! Could you sketch how you'd implement the awd via chain?

Also, I looked into your .89 nitro idea. They are called "Glow Engines", yes? They seem to be pretty cool, hehe. What are their fuel consumption like? Would you require a large fuel tank? Lets say that the rover will operate for around 1 hr. Max speed will be 4-5 km/h. I'm not too sure of the weight.. 20 kg maybe?

Back to using DC motors, here's some plus points to consider:
1- Runs on electricity. Rover will have one common power source to power all subsystems.
2- relatively small size. Can have multiple motors to implement the "direct wheel drive". If one motor fails, the rest can continue running. Thus, redundancy is assured.
3- Easy to swap DC motors depending on how its mounted.. only need to resolder the wire connections.
4- Very accurate control via programming.
5- When rover is stationary, DC motors will not consume any electricity. Its pretty much "power on demand".

Some bad points
1- even small, a collective weight of 4 DC motors might be heavy.
2- Will consume a lot of electricity if rover is going uphill or struggle over terrain.
3- need to expand battery size and/or amount to accommodate motors.

KINETIC_JOULES
I'm back guys!
Welcome back! Ok, now get back to work ๐Ÿ˜‰
xheavenlyx
xheavenlyx • Jul 14, 2008
https://sites.google.com/a/crazyengineers.com/ce-lab-projects/CE-Bot/case-studies

Hands down, I am in for building a rover something that is at least a tad-bit in league with any of the described rovers on the Updated Case studies page on celab.tk website (above). These are robo's from NASA or the Department of Defense.

Take your time to read about each of them. And also watch the videos. We will learn something about tracked system or the AWD and also the awesome system of all terrain wheel types. Pretty good.

I might add more to the list soon.

https://sites.google.com/a/crazyengineers.com/ce-lab-projects/CE-Bot/case-studies
raj87verma88
raj87verma88 • Jul 14, 2008
xheavenlyx
https://sites.google.com/a/crazyengineers.com/ce-lab-projects/CE-Bot/case-studies

Hands down, I am in for building a rover something that is at least a tad-bit in league with any of the described rovers on the Updated Case studies page on celab.tk website (above). These are robo's from NASA or the Department of Defense.

Take your time to read about each of them. And also watch the videos. We will learn something about tracked system or the AWD and also the awesome system of all terrain wheel types. Pretty good.

I might add more to them soon.

https://sites.google.com/a/crazyengineers.com/ce-lab-projects/CE-Bot/case-studies
All of these with the exception of the autonomous drilling bot, are using the chain. I agree with Gohm on the use of either chains or tracks instead of individual motors for each wheel. His idea of 0.89 nitro is also quite good. It is not very bulky, quite powerful for its size, providing good speeds to RC cars in which it is used.

@Ash:- Yes they are called glow engines also as they use glow plugs instead of spark plugs to ignite the fuel. The fuel used is called glow fuel which is either methanol or nitromethane. You can refer this link for more info Glow plug (model engine - Wikipedia, the free encyclopedia)
xheavenlyx
xheavenlyx • Jul 14, 2008
From Wiki Radio-controlled model - Wikipedia, the free encyclopedia:

development of technologies like brushless motors and lithium polymer batteries. These allow electric motors to produce much more power rivaling that of fuel-powered engines. It is also relatively simple to increase the torque of an electric motor at the expense of speed, while it is much less common to do so with a fuel engine, perhaps due to its roughness.
The main reason Glow engines cannot be used is because its practically impossible to control the torque (and speed in large variations). This is possible and efficient in electric motors. Plus we will be running our bots for hours and may also use solar power for longer uses, not 10 or 20 minutes as is possible with a glow engine used in RC cars.
raj87verma88
raj87verma88 • Jul 14, 2008
good point XhX. It skipped my mind, so Glows are out of question
Great work, xhx! We were sorely in need of case studies ๐Ÿ˜›

The 6 wheels is a compromise between tracks and using just 4 wheels. Tracks are not good when turning, in the sense that they require lots of power to overcome turning frictions. The actual "tracks" are an added weight. 4 wheels will not provide enough traction, and can get stuck in certain gaps or humps.

We can make the turning radius pretty tight using the ackerman equation, also keeping in mind that both the front and rear wheels have steering.

One thing I notice that if you are able to control each side of the wheels separately, you can possibly execute a neutral turn like tracked vehicles.

I suppose we can use a chain for each side of the wheels, albeit they'll be inside rather than out. That would reduce the amount of dc motors to 2 ๐Ÿ˜€ Of course, this assumes that we want the front and rear wheels to rotate at the same speed.
KINETIC_JOULES
KINETIC_JOULES • Jul 14, 2008
ash
Welcome back! Ok, now get back to work ๐Ÿ˜‰
*Salutes* Yes sir!
xheavenlyx
xheavenlyx • Jul 14, 2008
Good points everyone. But you know, everyone should see the videos.

First thing I noticed is the size. We have to know for sure that we are ok with and also finalizing a smaller robot like the Packbot (You should read the link before you ask whats a packbot) or have one as big as SCARAB.

As ash said, we will mostly use the 4/6 wheel config. BUT with good suspenstion system and flexibility. See second video on SCARAB (1:30 min) VERY VERY Important.
KINETIC_JOULES
KINETIC_JOULES • Jul 14, 2008
xheavenlyx
Good points everyone. But you know, everyone should see the videos.

First thing I noticed is the size. We have to know for sure that we are ok with and also finalizing a smaller robot like the Packbot (You should read the link before you ask whats a packbot) or have one as big as SCARAB.

As ash said, we will mostly use the 4/6 wheel config. BUT with good suspenstion system and flexibility. See second video on SCARAB (1:30 min) VERY VERY Important.
Is there supposed to be a link?
Maybe my computer is screwed up. . .
KINETIC_JOULES
KINETIC_JOULES • Jul 14, 2008
I've got an idea.
I was working on the sketch of the robot, when I was thinking about the wheel base. What If I made the front set and the middle set farther apart than the middle set and the back set of wheels, due to momentum.
I was thinking, since this is going to be all-terrain robot, the front two sets of wheels need to be independent meaning a 4-wheel drive instead of a 6-wheel drive; and the back set will be dependent on the front two. I figured you could increase momentum and decrease power use by making it a 4-wheel drive instead of a 6-wheel drive but increase the momentum so it would go faster.
Do you know what I'm trying to say?

1.) To increase momentum:
Separate the front set and the middle set of wheels farther apart than the middle and the last set.
2.) To decrease power use:
Make the front two wheels independent, meaning only the front two sets are motorized, while the back set is dependent on the front two sets and does not require power use.
3.) To put it all together:
This increases travel while decreasing power use.

Do you get what I'm trying to say?
raj87verma88
raj87verma88 • Jul 15, 2008
KINETIC_JOULES
I've got an idea.
I was working on the sketch of the robot, when I was thinking about the wheel base. What If I made the front set and the middle set farther apart than the middle set and the back set of wheels, due to momentum.
I was thinking, since this is going to be all-terrain robot, the front two sets of wheels need to be independent meaning a 4-wheel drive instead of a 6-wheel drive; and the back set will be dependent on the front two. I figured you could increase momentum and decrease power use by making it a 4-wheel drive instead of a 6-wheel drive but increase the momentum so it would go faster.
Do you know what I'm trying to say?

1.) To increase momentum:
Separate the front set and the middle set of wheels farther apart than the middle and the last set.
2.) To decrease power use:
Make the front two wheels independent, meaning only the front two sets are motorized, while the back set is dependent on the front two sets and does not require power use.
3.) To put it all together:
This increases travel while decreasing power use.

Do you get what I'm trying to say?
No, I do not get it. Explain your points.
KINETIC_JOULES
I've got an idea.
I was working on the sketch of the robot, when I was thinking about the wheel base. What If I made the front set and the middle set farther apart than the middle set and the back set of wheels, due to momentum.
I was thinking, since this is going to be all-terrain robot, the front two sets of wheels need to be independent meaning a 4-wheel drive instead of a 6-wheel drive; and the back set will be dependent on the front two. I figured you could increase momentum and decrease power use by making it a 4-wheel drive instead of a 6-wheel drive but increase the momentum so it would go faster.
Do you know what I'm trying to say?

1.) To increase momentum:
Separate the front set and the middle set of wheels farther apart than the middle and the last set.
2.) To decrease power use:
Make the front two wheels independent, meaning only the front two sets are motorized, while the back set is dependent on the front two sets and does not require power use.
3.) To put it all together:
This increases travel while decreasing power use.

Do you get what I'm trying to say?
Ah, you're thinking like 6 wheeled trucks yea? Actually, remember, the rear wheels can be steered too ๐Ÿ˜€

It may be 6 wheel, but we may choose to drive only the front and rear wheels. Its the middle set that is not powered (for now). It provides support for the middle section of the chassis, to avoid it from sagging in the middle, as well as some traction.

Also, its important to keep the distances equal to provide stability, stable steering (using the ackerman diagram here: https://www.crazyengineers.com/forum/ce-labs/2312-ce-project-ce-bot-5.html#post13795 ), as well as the ability to drive forward and backward with the same performance.. as the rover will tend to be biased towards one direction.

The link to the Scarab video is on the celab.tk website ๐Ÿ˜€ Gosh, its much bigger than I thought! Simply cool.

xhx, we might need to reconsider the design a little if you want that kind of flexibility. The wheels would have to be attached separately from the chassis or something.

This is another robot we can also look at. It has 6 wheels, and a super flexible frame:
BlueBotics > Products > Shrimp III
KINETIC_JOULES
KINETIC_JOULES • Jul 15, 2008
Nevermind, you guys. The thought was good in my head. I should just stick to the designing, for I am not smart enough to contribute any knowledgeable information.
So just pretend I didn't say that, and continue with the ideas.
xheavenlyx
xheavenlyx • Jul 15, 2008
Nevermind, you guys. The thought was good in my head. I should just stick to the designing, for I am not smart enough to contribute any knowledgeable information.
So just pretend I didn't say that, and continue with the ideas.
1. Shut up. Never say that. "I am not smart enough to contribute any knowledgeable information."

2. I read your idea. You know, Ash gave a reply. So if you still believe thats a good idea, make a design report. Try some calculations as I think you can have a point there (thats how we will move in the design process, facts from calculations), but yes we NEED to have front AND back powered. If the front two wheels are above the ground the remaining wheels have to run the BOT.

3. The link was in my earlier post: https://sites.google.com/a/crazyengineers.com/ce-lab-projects/CE-Bot/case-studies

4. @Ash: Yea exactly! I think we should have that kind of flex. We need it. Away from the chesis and with flexible links, something like the mars rover too. A mix. We have to design it properly.

5. Ash, Raj, KINETIC. We are reaching a state where the project is going pretty fast ๐Ÿ˜€ Now we can go a bit more mathematical. For every major design suggestion we must do a math study and write a small report (if possible).
KINETIC_JOULES
KINETIC_JOULES • Jul 15, 2008
xheavenlyx
1. Shut up. Never say that. "I am not smart enough to contribute any knowledgeable information."

2. I read your idea. You know, Ash gave a reply. So if you still believe thats a good idea, make a design report. Try some calculations as I think you can have a point there (thats how we will move in the design process, facts from calculations), but yes we NEED to have front AND back powered. If the front two wheels are above the ground the remaining wheels have to run the BOT.

3. The link was in my earlier post: https://sites.google.com/a/crazyengineers.com/ce-lab-projects/CE-Bot/case-studies

4. @Ash: Yea exactly! I think we should have that kind of flex. We need it. Away from the chesis and with flexible links, something like the mars rover too. A mix. We have to design it properly.

5. Ash, Raj, KINETIC. We are reaching a state where the project is going pretty fast ๐Ÿ˜€ Now we can go a bit more mathematical. For every major design suggestion we must do a math study and write a small report (if possible).
What I'm saying is:
What I posted earlier didn't make any sense. I realize now what I said.
The sketch I'm working on now, the wheel base it basically what I have. I'm still trying to figure out everything. It's really complicated.
xheavenlyx
xheavenlyx • Jul 15, 2008
Oops, sorry if the post came off as rude. lol, I was being sarcastic in the point #1. After that it was just other points ๐Ÿ˜€
KINETIC_JOULES
KINETIC_JOULES • Jul 15, 2008
It's okay. No biggie! ^_^ I just got google sketch up, and as soon as I figure out how to use it, I'll be working on the digital sketch of the bot.
KINETIC_JOULES
It's okay. No biggie! ^_^ I just got google sketch up, and as soon as I figure out how to use it, I'll be working on the digital sketch of the bot.
Kinetic, don't worry about sharing ideas. To be an engineer, you have to be confident in voicing out your ideas and thoughts. We are not here to criticize your ideas with malice: rather, we are here to discuss the points!

Doesn't matter if you are right or wrong.. whatever we discuss will be valuable to all. I've typed posts that seem a little silly (even when I was sure I was right), but understood better after discussions! Thats the problem we have in college classes.. most are scared or shy to ask the lecturer questions, in case he/she makes a fool out of themselves. This is the wrong mentality ๐Ÿ˜€

So be sure to read and analyze the replies you have, and understand the different perspectives if it differs from your original ideas. I'm still an "aspiring" engineer like you (albeit with a year left), and I learn quite a lot from Crazy Engineers thanks to the rest of the CEans who contribute to the discussions ๐Ÿ˜€

Good luck with the Google SketchUp. There should be lots of tutorials online available!

xheavenlyx
4. @Ash: Yea exactly! I think we should have that kind of flex. We need it. Away from the chesis and with flexible links, something like the mars rover too. A mix. We have to design it properly.

5. Ash, Raj, KINETIC. We are reaching a state where the project is going pretty fast ๐Ÿ˜€ Now we can go a bit more mathematical. For every major design suggestion we must do a math study and write a small report (if possible).
If we could embed the motors inside the wheel hubs (like the Shrimp robot), we will only need to worry about the steering mechanism. Thats the only thing thats troubling me at the moment.. because if you want the wheel to be super flexible, the motor shafts would also need to be flexible. I believe the only way to do that is to use multiple universal joints or something. Gohm and patty, can you confirm this?

Also, is the ackerman equation valid for the rover? We should start running calculations with it soon, like xheavenlyx said. I've never really fabricated it before, even with lego.. (not enough pieces).

Im sorry for my lack of wireless testing ๐Ÿ˜” I'm actually involved in another project at uni (CANSAT). The good thing is, it has a wireless aspect using radio modems and gps.. so I can indirectly source the research from that into CE Bot. ๐Ÿ˜Ž

I'll try doing something with the WiFi this weekend *prays*
KINETIC_JOULES
KINETIC_JOULES • Jul 15, 2008
Thanks, ash
As for my sketching progress. . . it's basically a pile of mess.
here's the ideas so far:

CE Bot design. Wheel base by ~AliceXinXchains on deviantART

Ce bot 2 by ~AliceXinXchains on deviantART

Ce Bot 3 by ~AliceXinXchains on deviantART

[โ€‹IMG]
KINETIC_JOULES
Thanks, ash
As for my sketching progress. . . it's basically a pile of mess.
here's the ideas so far:

CE Bot design. Wheel base by ~AliceXinXchains on deviantART

Ce bot 2 by ~AliceXinXchains on deviantART

Ce Bot 3 by ~AliceXinXchains on deviantART

[โ€‹IMG]
Good work, Kinetic! Much better than my first attempt in Google SketchUp ๐Ÿ˜›

Can you this time make the axle angular like a triangle. Something like this, from the front view:
   
   _
  / \
 0   0
Where the "0"'s are the wheels. Hope you understand! Check out the Shrimp robot link to see what I'm hinting at. It'll be interesting to see what it'll look like!
KINETIC_JOULES
KINETIC_JOULES • Jul 15, 2008
Like. . .I'm not getting it. The axle is supposed to be shaped like that?
Its an additional idea, a modification of the original lego design. You know when you stand up with your feet far apart? You legs are sorta angled. Imagine your shoes as the wheels.. something like that, haha.
KINETIC_JOULES
KINETIC_JOULES • Jul 15, 2008
Kinda like what I've already got?
gohm
gohm • Jul 16, 2008
Yes, you are correct on the joint idea ASh.

ash
Kinetic, don't worry about sharing ideas. To be an engineer, you have to be confident in voicing out your ideas and thoughts. We are not here to criticize your ideas with malice: rather, we are here to discuss the points!

Doesn't matter if you are right or wrong.. whatever we discuss will be valuable to all. I've typed posts that seem a little silly (even when I was sure I was right), but understood better after discussions! Thats the problem we have in college classes.. most are scared or shy to ask the lecturer questions, in case he/she makes a fool out of themselves. This is the wrong mentality ๐Ÿ˜€

So be sure to read and analyze the replies you have, and understand the different perspectives if it differs from your original ideas. I'm still an "aspiring" engineer like you (albeit with a year left), and I learn quite a lot from Crazy Engineers thanks to the rest of the CEans who contribute to the discussions ๐Ÿ˜€

Good luck with the Google SketchUp. There should be lots of tutorials online available!



If we could embed the motors inside the wheel hubs (like the Shrimp robot), we will only need to worry about the steering mechanism. Thats the only thing thats troubling me at the moment.. because if you want the wheel to be super flexible, the motor shafts would also need to be flexible. I believe the only way to do that is to use multiple universal joints or something. Gohm and patty, can you confirm thi

Also, is the ackerman equation valid for the rover? We should start running calculations with it soon, like xheavenlyx said. I've never really fabricated it before, even with lego.. (not enough pieces).

Im sorry for my lack of wireless testing ๐Ÿ˜” I'm actually involved in another project at uni (CANSAT). The good thing is, it has a wireless aspect using radio modems and gps.. so I can indirectly source the research from that into CE Bot. ๐Ÿ˜Ž

I'll try doing something with the WiFi this weekend *prays*
xheavenlyx
xheavenlyx • Jul 17, 2008
Excellent work KINETIC! I loved the last design (#8) But I think dont spend a lot of time on that rite now, keep doing it side by side. There is something important that you will have to do in some time.

I will post what it is soon. And its very important ๐Ÿ˜€
KINETIC_JOULES
KINETIC_JOULES • Jul 17, 2008
Thanks! It's basically how I progressed. They're in order. I'm glad you like it! And so, what you're saying is just wait and don't work on the design right now? You have something in mind?
xheavenlyx
xheavenlyx • Jul 17, 2008
READ THIS POST CAREFULLY. IMPORTANT!


[โ€‹IMG]

Ok, I have a proposal.

Before we start finalizing the chassis design, we need to know what the chassis will be holding. Its like building a foundation without knowing if the building is a high-rise or a storeroom!

Plus we will also know the power requirment and the total weight of payload.

===========================================

So our next task is SENSORS:

1. Find the properties for each sensor type. Main points like Input method and Output method. (see example at end)

2. Find various alternatives or vendor specific devices.

3. Datasheet for each sensor or specifications from website.

4. Lastly, why you think we should use the specified sensor (optional).

===EXAMPLE===

1. Video Camera: "Various properties..." then Input: HW:USB, SW:. Output: HW: USB, SW: ideodata,

2. There are many cameras so we can see the cheapest and most flexible one, like with more range of operating resolution 300x600 to 1270x700). (This is just an example).

3. Find datasheet or if not then specifications from product website.

4. "This perticular model has ... this ... and thats why we should use it...blah blah".

===END EXAMPLE===

So tell me who wants to take which sensors. If there is an overlap we will look at that and deside by tommorow.

The research must finish within a week. ๐Ÿ˜€ The final report will be after that.
KINETIC_JOULES
KINETIC_JOULES • Jul 17, 2008
I'm still concerned about the body design. . . and do you mind if I experiment with the sensors later?
Xhx, a week? ๐Ÿ˜›

Thats a great diagram you drew. Things are more organized now!

I'll take the camera. I've already done some research on it for my CANSAT project. We have two options.. either we hack an existing webcam, or we fabricate our own camera using CCD imagers. At the moment, a webcam hack is doable because you'll connect it directly to the laptop through USB. No need to worry about decoding the USB signals ๐Ÿ˜‰

I propose this webcam:
Philips SPC900NC
CCD sensor: Sony ICX098BQ
Resolution: 640X 480
Pixels: 300K
Pixel size: 5.6 micron

We can mount a better lens on the existing one for better image quality, as well as put it on servos so it can rotate in the x-y axi. If possible, we can also make a mechanism to automatically change the image filters, so we could switch from normal to infrared views ๐Ÿ˜‰

I'll upload other webcams and the datasheets of their CCD sensors on CE Lab tomorrow or the day after.

I might as well take the light sensors as well, unless someone else wants its.

@ Kinetic
Keep up the good work! By the way, the word "censor" is almost an antonym of "sensor" if you think about it ๐Ÿ˜‰ Don't confuse the two!
raj87verma88
raj87verma88 • Jul 18, 2008
What are the expected weights and sizes of the equipments that will be fit on the robot. I mean other than the drive train and chases.
KINETIC_JOULES
KINETIC_JOULES • Jul 18, 2008
ash
@ Kinetic
Keep up the good work! By the way, the word "censor" is almost an antonym of "sensor" if you think about it ๐Ÿ˜‰ Don't confuse the two!
Sorry. That was an accident!
I gave an estimation of 20Kg before, but that was a number I pulled out of thin air (sorta). Sensors are quite negligible in size and weight compared to other subsystems. The heaviest stuff would probably be the batteries, motors, wheels, laptop as well as additional actuators such as grippers.

At the beginning, the max footprint that I proposed was the size of a standard magazine. Perhaps we should extend that to around A3 size (just the body).. it looks enough for our purposes.

We could certainly find out these weights in our research stuff, if one takes the time to do it though ๐Ÿ˜”
KINETIC_JOULES
KINETIC_JOULES • Jul 18, 2008
Did you happen to see that I made a place for the lap top in my design. That's just where it's supposed to sit. ^_^ what do ya think?
raj87verma88
raj87verma88 • Jul 18, 2008
I was just thinking, that we need to have an approximate idea of the total weight that the chases and wheels will support. It would help in the designing and fabrication of these parts. It would also help in the stress calculation and other equivalent stuff.
xheavenlyx
xheavenlyx • Jul 18, 2008
@Raj
I was just thinking, that we need to have an approximate idea of the total weight that the chases and wheels will support. It would help in the designing and fabrication of these parts. It would also help in the stress calculation and other equivalent stuff.
Thats what I said we have to do. Its the most important thing, and it IS NOT EASY!

@Kinetic

Ok, I will need some time to think of this. If you are interested to do the chasis rite now. Then I want you to read about the rocker-bogie design and incorporate in your present idea. Here are links:

WIKI: Rocker-bogie - Wikipedia, the free encyclopedia
PDF: https://kipr.org/papers/robotics02.pdf

@Ash.

Ash, please, I am going crazy here. I need to know what the robot will be used for and in which environment. Again, its like building a house without knowing if we need a slant roof for snow or a cement house for tropics.

IF robot is used to mapping in deserts THEN it has to be a bit bigger, more than 20 KG and that will depend on Sensors, environment and abilities.

IF Robot is used in forest areas for trespassing violations (Border security, airport security) then it has to be long lasting, sturdy and weather proof. Everything changes.

And so on...

Ash, you know I was confused before too. So are we SURE we will be going with Remote Sensing, Mapping robot? For laaaaarge areas and weather intensive, can survive for days using solar power and GPS (I have a GPS module that can be sacrificed)? Wont that be a good project? We already have 15 year old's building useless sensor bots...too comon. We need a something that can SURVIVE! ๐Ÿ˜€ What do you think of this idea?
bayazidahmed
bayazidahmed • Jul 18, 2008
Hi guys!

After a long time, huh? I remember promising to do the block diagram and then left, couldnt help it.

I was going through all the posts of CE:Bot and this CE:Bot 2. And whoa you people have done a load of good job (and I feel that everyone here is smitten by the drive system ๐Ÿ˜‰).

Anyways, going into the topic, my knowledge(the areas where I can help) includes Sensors, Processor(s), Drive System, Power Supply Unit(s) and Communications.
But of these I personall dislike the last two(Power Supply Unit(s) and Communications), which leaves me with three topics.

1. Sensors - I dont have practical access to any of the sensors mentioned, but I do have a good knowledge and a very good googling capability. Which means I will not be able to provide the exact details of how each thing works, but can help you guys in searching for the datasheets, and any other information you want.

2. Ah, I feel at home when discussing them. My true love, programming *blush*. I remember reading somewhere in the discussion regarding the language to be used, Python (and was Ruby also discussed?). Why? Firstly, Do they have compilers for RTOS, linux and PIC/ATMEL? I dont think so. Secondly, Do they support assembly langauge instructions. Again, I dont think so. Third, Do they support low level instructions? Again, I dont think so. Then why python? The only language that can be effectively used in this case is C/C++. And regarding the use of either PIC or ATMEL, both are good, anyone of them can be used. I think ATMEL is easier and powerful to work with. My suggestion is to use each PIC/ATMEL for each module (like for the drive sstem, one powerful micro-controller, for each sensor, smaller micro-controllers for which the requirement of RAM, ports, etc... is not much).
I'll divulge in detail when the turn comes (Maybe xhx will get angry at me for discusing processors when the current turn was for sensors).

3. I think ash's idea of indepently powered wheels is very good, which gives u an excellent control, flexiblity, durability, and easy to program.

I think its enough for now, the post size is getting longer and I am getting sleepier :sleepy:.

Waiting for comments...
xheavenlyx
@Ash.

Ash, please, I am going crazy here. I need to know what the robot will be used for and in which environment. Again, its like building a house without knowing if we need a slant roof for snow or a cement house for tropics.

IF robot is used to mapping in deserts THEN it has to be a bit bigger, more than 20 KG and that will depend on Sensors, environment and abilities.

IF Robot is used in forest areas for trespassing violations (Border security, airport security) then it has to be long lasting, sturdy and weather proof. Everything changes.

And so on...

Ash, you know I was confused before too. So are we SURE we will be going with Remote Sensing, Mapping robot? For laaaaarge areas and weather intensive, can survive for days using solar power and GPS (I have a GPS module that can be sacrificed)? Wont that be a good project? We already have 15 year old's building useless sensor bots...too comon. We need a something that can SURVIVE! ๐Ÿ˜€ What do you think of this idea?
My good friend, we have to realise that this is our first prototype! Haha.. for sure, no robot design is perfect on the first try. We need to start small, then scale up. Remember, our robot is designed to be modular, so we can always enlarge the size later. We need to focus on the functionality first, rather on reliability and survivability. Once we score on the sensors, communications and movement over rough terrain, we would have completed our first objectives. So indeed, we are still doing a remote sensing and mapping robot, but we dont need highly sophisticated robot to do that yet.

After we know they work, we can start focusing on secondary objectives. We never really discussed about long term survivability until recently. I gave an estimate of 1 hr when we first started, which is long enough to collect some sort of data. If we manage that, then we can move on to install solar panels and other added enchancements. The fact that we are using your laptop means it provides is with flexibility on configurations. At least we do not have to fabricate that many new PCB's ๐Ÿ˜€

bayazidahmed
1. Sensors - I dont have practical access to any of the sensors mentioned, but I do have a good knowledge and a very good googling capability. Which means I will not be able to provide the exact details of how each thing works, but can help you guys in searching for the datasheets, and any other information you want.

2. Ah, I feel at home when discussing them. My true love, programming *blush*. I remember reading somewhere in the discussion regarding the language to be used, Python (and was Ruby also discussed?). Why? Firstly, Do they have compilers for RTOS, linux and PIC/ATMEL? I dont think so. Secondly, Do they support assembly langauge instructions. Again, I dont think so. Third, Do they support low level instructions? Again, I dont think so. Then why python? The only language that can be effectively used in this case is C/C++. And regarding the use of either PIC or ATMEL, both are good, anyone of them can be used. I think ATMEL is easier and powerful to work with. My suggestion is to use each PIC/ATMEL for each module (like for the drive sstem, one powerful micro-controller, for each sensor, smaller micro-controllers for which the requirement of RAM, ports, etc... is not much).
I'll divulge in detail when the turn comes (Maybe xhx will get angry at me for discusing processors when the current turn was for sensors).
Welcome back, again ๐Ÿ˜› Actually, we will still be using other languages. The beauty of Python is that it can work well with C/C++, or other langs. We use Python for high level non-critical tasks in the laptop itself. Python gives us a lot of ease and flexibility, and allows us to change code faster if we need to. It is also portable.. works in any platform (yes, it can run in Linux!). For critical processes, we will stick to ASM and C/C++. Though, xhx knows more about its application in CE Bot than I do ๐Ÿ˜›

Have you given Python a try? its quite awesome..
Python Programming Language -- Official Website

Heres a link to applications of python in robotics:
Pyro, Python Robotics: Pyro

For sure we will use a uC for each module. Its just that they are all interfaced together to the laptop (along with data & image processing stuff). The laptop also acts as the interface between the modules and the computer host (since we may choose to use remote control).

3. I think ash's idea of indepently powered wheels is very good, which gives u an excellent control, flexiblity, durability, and easy to program.

I think its enough for now, the post size is getting longer and I am getting sleepier :sleepy:.

Waiting for comments...
Yeah, xhx's Rocker-bogie idea works well with the independent motors. Though, we'll have a nightmarish time figuring out how to supply enough power to them ๐Ÿ˜›
KINETIC_JOULES
KINETIC_JOULES • Jul 19, 2008
xheavenlyx
We already have 15 year old's building useless sensor bots...too comon. We need a something that can SURVIVE! ๐Ÿ˜€
I was just going by what y'all were saying. Not like it's entirely my fault. I'm designing what you say to design. And they were just experiments anyway. I could always do something different. That's all you have to say. I'm not going to be immature and say I quit the team, because that doesn't solve anything, but I want to feel like I'm doing something important and productive, and not do something in vein for you to just laugh at. If it's useless. . . why didn't you tell me that to begin with? Why didn't you say do something different? If what I'm trying to contribute is useless. . . what's the point of having me around?
KINETIC_JOULES
I was just going by what y'all were saying. Not like it's entirely my fault. I'm designing what you say to design. And they were just experiments anyway. I could always do something different. That's all you have to say. I'm not going to be immature and say I quit the team, because that doesn't solve anything, but I want to feel like I'm doing something important and productive, and not do something in vein for you to just laugh at. If it's useless. . . why didn't you tell me that to begin with? Why didn't you say do something different? If what I'm trying to contribute is useless. . . what's the point of having me around?


You know, that was an innocent mistake. I dont think xhx knew you are 15.. what a horrible coincidence.

Chill, Tyler. He meant amateur robots that have no real objectives and profound benefits to society, thats all. Your designs have nothing to do with his statements. I'll bet you that the next time he logs in, he'll be apologizing his heart out for the misunderstanding ๐Ÿ˜‰

Carry on with it. Seriously.. your designs are kick ass. Here's a lego design with some changes made. The red objects are the DC motors, and the blue the suspension. I have no idea what steering method works with this configuration.. maybe independent servos? Thats pushing our luck, though.
[โ€‹IMG]
KINETIC_JOULES
KINETIC_JOULES • Jul 19, 2008
ash
You know, that was an innocent mistake. I dont think xhx knew you are 15.. what a horrible coincidence.

Chill, Tyler. He meant amateur robots that have no real objectives and profound benefits to society, thats all. Your designs have nothing to do with his statements. I'll bet you that the next time he logs in, he'll be apologizing his heart out for the misunderstanding ๐Ÿ˜‰
I'm sorry. . . I'm just stressed. *tears* I didn't mean to sound like that. Forgive me?
And the design is GREAT! Really good job! That's what I thought you were talking about with the axles. . . but it was too late to change it in sketch up.
*thumbs up* its cool

I want to try doing the Rocker-bogie design that xhx suggested on MLCAD. The good thing is I can colour-code lego components, so its easy to see which subsystems is what. If someone has enough lego pieces (as well as the electric stuff), they can construct a mini model of CE Bot in real life!
KINETIC_JOULES
KINETIC_JOULES • Jul 19, 2008
ash
*thumbs up* its cool

I want to try doing the Rocker-bogie design that xhx suggested on MLCAD. The good thing is I can colour-code lego components, so its easy to see which subsystems is what. If someone has enough lego pieces (as well as the electric stuff), they can construct a mini model of CE Bot in real life!
That would be cool! I don't own any legos anymore. . . I lost them years ago. *thinks for a minute* wait! Yes I do!
gohm
gohm • Jul 19, 2008
Ash, I would only share a servo for both sets of steering. Simple, more reliable and less weight. You'll only need to trim one servo that way.
raj87verma88
raj87verma88 • Jul 19, 2008
@ Ash: A good design buddy. Let me see, You have a rack and pinion on both sides. Just wondering, why the middle set of wheels do not have those spring shockers. From your designs it seems that you want the bot chases in the lines of a Baja or dune buggy. That is a good idea, but we can try others too and settle for the one which is best.

@ Tyler: Wow, quite a big misunderstanding between two team members. I know that Ash has already calmed you but I have to say something. Tell me has anyone ever said that you are unimportant to the team or to CE in general. Have we not encouraged you in your designs. We know you are not an engineer and at the age of 15 we don not expect you to have the knowledge and experience of one. That is why you were given the job of designing. Frankly speaking, your designs are good but when we start fabricating the bot we will have to make a few or more modifications on your designs because we will have to consider the forces and calculate stuff and other things. And as the bot completes you will gain a lot of knowledge and experience. You are so lucky that you will gain such an experience at 15 while we in our 20s. I wish I was your age. In the end I apologize on behalf of CE and all its members if in any way you have been wronged. You are going to join an engineering school in the future and it is our duty to answer your queries so that when you join a univ. you will be ahead of your mates. This is the idea of CE, to help and support each other and have co-operation among ourselves.
gohm
Ash, I would only share a servo for both sets of steering. Simple, more reliable and less weight. You'll only need to trim one servo that way.
You are right, gohm. Other than the points you mentioned, we also wouldn't need to worry about the steering synchronizing with each other properly if they share the same servo. The biggest problem I see is that we need a long shaft down the middle of the bot:
0-----0
   |
0-----0
   |
0-----0
It'll take up valuable space. Either we rid of it entirely and use 2 servos.. or, perhaps we can offset it to the side, and use some gears to mesh the shaft with the pinions at both ends:
0-----0
     |
0-----0
     |
0-----0
I hope the "text art" is understandable. A little lazy to open a graphics program ๐Ÿ˜›


raj87verma88
@ Ash: A good design buddy. Let me see, You have a rack and pinion on both sides. Just wondering, why the middle set of wheels do not have those spring shockers. From your designs it seems that you want the bot chases in the lines of a Baja or dune buggy. That is a good idea, but we can try others too and settle for the one which is best.
Thanks! Ah yes, I should have put the springs in the middle too! Haha. Still need to work on it. The support will surely disintegrate easily due to the mass of the motors too. Try out MLCAD, Patty. Its pretty fun! Just takes a while getting used to positioning the lego components. The "springs" are generated.. you'll only need to input some parameters.

Theres some interesting Lego buggy designs we can take a look at, along with their construction guide so we could see their "insides". Will try to find them later.

And Yep, we'll certainly try other designs. We sorely need a "tracked" version for comparison.
KINETIC_JOULES
KINETIC_JOULES • Jul 20, 2008
raj87verma88
@ Tyler: Wow, quite a big misunderstanding between two team members. I know that Ash has already calmed you but I have to say something. Tell me has anyone ever said that you are unimportant to the team or to CE in general. Have we not encouraged you in your designs. We know you are not an engineer and at the age of 15 we don not expect you to have the knowledge and experience of one. That is why you were given the job of designing. Frankly speaking, your designs are good but when we start fabricating the bot we will have to make a few or more modifications on your designs because we will have to consider the forces and calculate stuff and other things. And as the bot completes you will gain a lot of knowledge and experience. You are so lucky that you will gain such an experience at 15 while we in our 20s. I wish I was your age. In the end I apologize on behalf of CE and all its members if in any way you have been wronged. You are going to join an engineering school in the future and it is our duty to answer your queries so that when you join a univ. you will be ahead of your mates. This is the idea of CE, to help and support each other and have co-operation among ourselves.
No need for apologies. No one has told me I'm unimportant. I'm just a little stressed out at the moment, that's all.
raj87verma88
raj87verma88 • Jul 20, 2008
KINETIC_JOULES
No need for apologies. No one has told me I'm unimportant. I'm just a little stressed out at the moment, that's all.
Take your time to sort out your mind. Stress is not good for health. Do something that you enjoy doing. You may talk about your problems to someone close, someone who will listen to you and not give advice after every sentence you speak. Take care.
KINETIC_JOULES
KINETIC_JOULES • Jul 21, 2008
raj87verma88
Take your time to sort out your mind. Stress is not good for health. Do something that you enjoy doing. You may talk about your problems to someone close, someone who will listen to you and not give advice after every sentence you speak. Take care.
Actually. . . I do that. I just need more sleep. 3 - 5 hours a day ain't cutting it!
KINETIC_JOULES
KINETIC_JOULES • Jul 21, 2008
xheavenlyx
@Kinetic

Ok, I will need some time to think of this. If you are interested to do the chasis rite now. Then I want you to read about the rocker-bogie design and incorporate in your present idea. Here are links:

WIKI: Rocker-bogie - Wikipedia, the free encyclopedia
PDF: https://kipr.org/papers/robotics02.pdf
I'm gonna sound a little dumb, but what is that? *points to the word chasis* I know I should already know what that is. . .
raj87verma88
raj87verma88 • Jul 21, 2008
Chases is the skeleton. Commonly used in the reference of vehicles. It is the framework around which supports all other things and around which the outer body is made. If you remove all parts of the car, the cage like structure that you are left with is the chases.
You may refer here Chassis - Wikipedia, the free encyclopedia
KINETIC_JOULES
KINETIC_JOULES • Jul 21, 2008
raj87verma88
Chases is the skeleton. Commonly used in the reference of vehicles. It is the framework around which supports all other things and around which the outer body is made. If you remove all parts of the car, the cage like structure that you are left with is the chases.
You may refer here Chassis - Wikipedia, the free encyclopedia
Wow. . . that's exactly what I thought it was. Thanks. . . Isn't that what we're trying to work on atm?
Yep, indeed ๐Ÿ˜€

Other than seeing what the CE Bot may look like, we also are interested on how the parts are connected to each other.
xheavenlyx
xheavenlyx • Jul 23, 2008
This is one design I was talking about. I still have to write about it in detail on celab.tk and here. So till I do that watch this video.

Some important points with this design is:

1. All wheels are 90% of the time are touching the surface (grounded). theoretically its 100%.

2. This design works well at low-speeds. Which is ok since for our mapping feature, we need to be at "good" speeds.

3. Only front and back wheels are motorized, and steerable by 4 servos. Dont worry about weight, servos are light compared to other components.

4. Middle set of wheels are free rotating.

5. Description of suspension we might use, from Wiki (Rocker-bogie - Wikipedia, the free encyclopedia):
The design uses a two-wheeled rocker arm on a passive pivot attached to a main bogie that is connected differentially to the main bogie on the other side. The body of the rover is attached to the differential such that it is suspended at an angle that is the average of the two sides. The ride is further smoothed by the rocker which only passes on a portion of a wheel's displacement to the main bogie.
6. Working explanation:
In order to go over an obstacle, the front wheels are forced against the obstacle by the rear wheels. The rotation of the front wheel then lifts the front of the vehicle up and over the obstacle. The middle wheel is then pressed against the obstacle by the rear wheels and pulled against the obstacle by the front until it is lifted up and over. Finally, the rear wheel is pulled over the obstacle by the front two wheels. During each wheel's traversal of the obstacle, forward progress of the vehicle is slowed or completely halted. This is not an issue for the operational speeds at which these vehicles have been operated to date.


The Video:::
https://www.youtube.com/v/VPpzbl-2uQE

The software used for simulation is Phun, Physics Sandbox. Try it out! Phun - 2D physics sandbox - Main Page
KINETIC_JOULES
KINETIC_JOULES • Jul 23, 2008
There was something that bugged me about the first test. Nice job on the video by the way. The second and third tests had their ups and downs as well, but I liked them much better than the first test. I liked the wheel base idea on the third test.
xheavenlyx
xheavenlyx • Jul 23, 2008
What are the points that you find irritating? Pros and Cons?
KINETIC_JOULES
KINETIC_JOULES • Jul 23, 2008
I felt the chassis of the robot would move about more than necessary. I can't explain it. I'm just paranoid about the fact that some of the hardware would get damaged or something. That's just me though. I know it sounds stupid.
xheavenlyx
xheavenlyx • Jul 23, 2008
Good you shared your thoughts, I will reply to it tomorrow after few more people have given their feedback.

If you do have time today, read the Wiki for Rocker Bogie so you can ask more questions or clear doubts in the meantime (Its 3:15 am here rite now ๐Ÿ˜€
KINETIC_JOULES
KINETIC_JOULES • Jul 23, 2008
Okay. It's 6:20 PM here. I'll read it.
is the bot ready!!!were it is stuck,
Ready? We wish! ๐Ÿ˜›

We are still in the designing stage, actually. Check out celab.tk to see our progress.

Please do give us your suggestions and comments.

------------------------------------------------------------
xhx, thats a great simulation! There are some things we are assuming though: the tires have 100% traction, and that the maximum speed is very slow. I suggested 4 km/h (which is around 1 m/s) last time. Can it still work at that speed? I suppose we need detailed sensors to tell the motors to slow down when necessary

Could you simulate shock absorbing in that program?

One more thing: I think its quite hard to design the "differential" without a lot of research and calculations ๐Ÿ˜› The whole frame of the rocker-bogie would have to be quite large relative to the payload as well.
xheavenlyx
xheavenlyx • Jul 24, 2008
xhx, thats a great simulation! There are some things we are assuming though: the tires have 100% traction[1], and that the maximum speed is very slow[2]. I suggested 4 km/h (which is around 1 m/s) last time. Can it still work at that speed? I suppose we need detailed sensors to tell the motors to slow down when necessary[3]

Could you simulate shock absorbing in that program?[6]

One more thing: I think its quite hard to design the "differential" without a lot of research and calculations[4] [โ€‹IMG] The whole frame of the rocker-bogie would have to be quite large relative to the payload[5] as well.
[1] "the tires have 100% traction" : We can assume they have 90% traction, normal rubber wheels will have it IF we know our working surface. Remember I asked what environment our Bot will run on? It depends on that completely.

[2] "maximum speed is very slow" : Yes thats true. The speed can heavily depend on the surface its driving too, if it goes faster than .5 meters per second going above obstacles then I think it will cause a lot of shock to the payload. Again depends if we are driving on a rocky obstacle land, or indoors like warehouses and offices with small obstacles. See below for LEGO using RB videos...we can drive fasttttt with RB if there are no obstacles. I will do a simulation for that too.

[3] "I suppose we need detailed sensors to tell the motors to slow down when necessary" Thats a given, we have no bot without that. We need that, otherwise again we will be making a bot that are mass made in "workshops" and "robotic courses" by kids. How it can be done and to what extent, dont worry we can change that anytime in the programming (make it simple or complex) ๐Ÿ˜€ Normal encoders at wheels and an accelerometer can tell the "slip" and calculate the error.

[4] "I think its quite hard to design the "differential" without a lot of research and calculations" Its not. Ive read the MARS rover suspension design in an IEEE Robotics and Automation MARS Special ๐Ÿ˜‰ (love that edition). It needs a gearbox on both connecting ends with 2 different configs. One has a planetary type[LINK] and the other a star type(Sun?[LINK]). We can read about it because building a robot isnt easy if we want it to be useful or a worthwhile effort (see end of this post).

[5] "frame of the rocker-bogie would have to be quite large relative to the payload" I think you should check out examples...here are a few videos of LEGO's using Rocker-Bogie!

1. YouTube - LEGO NXT Rocker-Bogie Suspension Demo I
2. YouTube - LEGO Sojourner - Rocker Bogie Suspension - No. 1
3. YouTube - LEGO NXT Rocker-Bogie Suspension Demo II

[6] "Could you simulate shock absorbing in that program?" Its a bit difficult, and we might need to resort to proper software for that, because the weights and size in that program are very difficult to match. I might be able to do that in MATLAB, but only as a last resort. I will think about it. Good point.


Ok, Lastly, if we are making a simple bot, I am totally in for it. But no Laptop and no accelerometer. A bump switch, ultrasound sensor, ir sensor and another bump switch, that will be enough. and a simple suspension that we find in RC cars. Oh yea, a PIC controller.
KINETIC_JOULES
KINETIC_JOULES • Jul 24, 2008
xhx, I REALLY liked the Sojourner! I loved the wheel base design.
Question: How would the chassis design fit with the Sojourner? I mean, unlike the other two, the body doesn't really move about as much, and that's a good thing. I want to start working on a design with the Sojourner's wheel base, but not sure how to station the chassis. Do you understand what I'm saying? It's hard for me to explain things.
xheavenlyx
xheavenlyx • Jul 24, 2008
good question Ty. But firstly, the Video showing Sojourner also uses the Rocker-Bogie wheel base (notice the two wheels going over stuff and the single one too)

As for fitting it to the payload, that can be done later because we still need to make the payload "box" which will contain the sensors, processor, batteries, and all the robot stuff. After we finish the payload (robot stuff) we can fix it with the chassis. So you can do two things now.

1. Start reading about gear systems (2 links provided in the above post). That will be for connecting the left wheel set and the right wheel set for the robot. Its the gear system that makes the bot more stable!! And believe me its a lot simpler than what it might look like.(I am kinda scared of it too...but thats what engineering is about ๐Ÿ˜€ Imagine a rod going through the bot connecting the two bases with gear box on both sides. Again, you will have to read about it because its impossible to write everything here. (again, 2 links provided in the above post)

2. Or you can wait for a while and see what design gets finalized ๐Ÿ˜€ and then help us with that. I reallllyyyy need someone to do good research for us! If we dont read and learn, then it will not be easy (something like re-inventing the wheel and wasting a lot of time).
KINETIC_JOULES
KINETIC_JOULES • Jul 24, 2008
xheavenlyx
good question Ty. But firstly, the Video showing Sojourner also uses the Rocker-Bogie wheel base (notice the two wheels going over stuff and the single one too)
Yes, I'm aware of that.


xheavenlyx
1. Start reading about gear systems (2 links provided in the above post). That will be for connecting the left wheel set and the right wheel set for the robot. Its the gear system that makes the bot more stable!! And believe me its a lot simpler than what it might look like.(I am kinda scared of it too...but thats what engineering is about ๐Ÿ˜€ Imagine a rod going through the bot connecting the two bases with gear box on both sides. Again, you will have to read about it because its impossible to write everything here. (again, 2 links provided in the above post)
What two links?
[EDIT]
Never mind about that.

xheavenlyx
2. Or you can wait for a while and see what design gets finalized ๐Ÿ˜€ and then help us with that. I reallllyyyy need someone to do good research for us! If we dont read and learn, then it will not be easy (something like re-inventing the wheel and wasting a lot of time).
I'd be happy to do research! It's better than sitting on my bum all day, trying to figure out what to do.
[EDIT]
What research, exactly?
Well i dont have much knowledge about gears,but i feel the bot shub be extremely flexible to move,so separate wheels will do,and will the bot have speed variations to move???anyhow we have to also look that its motion doesnt consume too much power
Thanks for the detailed reply, dude!

xheavenlyx
[1] "the tires have 100% traction" : We can assume they have 90% traction, normal rubber wheels will have it IF we know our working surface. Remember I asked what environment our Bot will run on? It depends on that completely.
Rightly so.. I guess it'll be dirt/grass/muddy/rocky sort of terrain. Places a 4x4 vehicle would usually traverse, except the desert or snow. We could extend our mission to those terrains in later iterations of CE Bot though.

[3] "I suppose we need detailed sensors to tell the motors to slow down when necessary" Thats a given, we have no bot without that. We need that, otherwise again we will be making a bot that are mass made in "workshops" and "robotic courses" by kids. How it can be done and to what extent, dont worry we can change that anytime in the programming (make it simple or complex) ๐Ÿ˜€ Normal encoders at wheels and an accelerometer can tell the "slip" and calculate the error.
I think the placement of sensors is key too! The programming can only do as much as the existing hardware available, hehe.

[4] "I think its quite hard to design the "differential" without a lot of research and calculations" Its not. Ive read the MARS rover suspension design in an IEEE Robotics and Automation MARS Special ๐Ÿ˜‰ (love that edition). It needs a gearbox on both connecting ends with 2 different configs. One has a planetary type[LINK] and the other a star type(Sun?[LINK]). We can read about it because building a robot isnt easy if we want it to be useful or a worthwhile effort (see end of this post).
Ah, thats good then! Hopefully we could find one ready made, or else we'd have to fabricate it ourself using CNC milling to fit our dimensions. Then you'd REALLY need to make calculations ๐Ÿ˜‰ If we take the "ready made" route, we'll try finding the suitable sizes. Its most likely we'd have to choose one and design our CE Bot according to those dimensions, and not the other way round. Thats an easier approach I suppose. But.. I remember discussing with Patty about differentials before, he said he can try designing them. We'll see what he says about this.

[5] "frame of the rocker-bogie would have to be quite large relative to the payload" I think you should check out examples...here are a few videos of LEGO's using Rocker-Bogie!

1. YouTube - LEGO NXT Rocker-Bogie Suspension Demo I
2. YouTube - LEGO Sojourner - Rocker Bogie Suspension - No. 1
3. YouTube - LEGO NXT Rocker-Bogie Suspension Demo II
Cool videos xhx ๐Ÿ˜€ You know, the rocker bogie frames of the NXT lego were quite large compared to the payload. That means you agreeing with my statement yea? ๐Ÿ˜›

The Sojourner video would be the counter of that. That one looks very promising ๐Ÿ˜€

But here's my concern: we cannot compare legos to our bigger and much heavier CE Bot. Remember the scaling law, how a flea can jump 200 times it's length, and not a elephant? I've used lego's before for prototyping robots, but when you actually build the latter, your facing different materials. Lego plastic bricks are strong for their size.. but a robot frame consist of denser and heavier material like metal. Once you add the bolts, screws and the heavy as hell Lead acid batteries, you may need a large rocker-bogie frame to support the payload. Thats what I meant by the relative weight thing. It may be 1:1 ratio.. or more Unless of course we aim to use different materials like carbon fiber.

[6] "Could you simulate shock absorbing in that program?" Its a bit difficult, and we might need to resort to proper software for that, because the weights and size in that program are very difficult to match. I might be able to do that in MATLAB, but only as a last resort. I will think about it. Good point.
Thats great, it'll be nice to see them!

Ok, Lastly, if we are making a simple bot, I am totally in for it. But no Laptop and no accelerometer. A bump switch, ultrasound sensor, ir sensor and another bump switch, that will be enough. and a simple suspension that we find in RC cars. Oh yea, a PIC controller.
Are you being serious or sarcastic here? ๐Ÿ˜›

Alright, we should really start researching for weights of the heaviest components: Motors (DC + servos), lead acid batteries (or other types), wheels, gears, differential, etc. Get yer "google skills" in gear, CEans!

Gohm and Patty, we really need your inputs about are latest discussions, please ๐Ÿ˜€ What do you guys think about the Rocker-Bogie design?
xheavenlyx
xheavenlyx • Jul 25, 2008
Freaking excellent. Hehe, Its exciting to see good discussions here!

1. Exactly, the surfaces you pointed out are exactly what a bot must go through with exception of pure sand and snow. Those bot designs are "special" ๐Ÿ˜€. Good, ill have to keep the terrain in mind for future calcs now.

2. Sensor placement is very important and will be done in step with the motor fitting and turning servos design on the wheel base. Hand in hand planing. cool ๐Ÿ˜€

3. In US for sure I know, there are small companies that will design a gear box for you for use in hobby projects, you give em design and material. I dont know if its there in India, just sent a PM to Biggie and others to ask that! ๐Ÿ˜€ And hopefully we will have a few design properties that are spcificly for ready made stuff. And the differential gear doesnt have to be that accurate. (next point is related...)

but a robot frame consist of denser and heavier material like metal. Once you add the bolts, screws and the heavy as hell Lead acid batteries, you may need a large rocker-bogie frame to support the payload. Thats what I meant by the relative weight thing. It may be 1:1 ratio.. or more Unless of course we aim to use different materials like carbon fiber.
Yea, you are right about the size. One thing I can think we can consider is to concentrate on the "maaain part of RB". You know, the two wheels that are free rotating. Thats the most important thing for ruggie terrain.. We can and should have two designs to consider later, not much of a worry if RB fails.


Another point, the design I showed on Phun was nothing near the actual working of a Rocker-bogie! Basically the payload is attached to only one pivoting joint! Thats the differential joint (geared rod connecting R and L sides), thats called the Rocker, the bogie is just 2 wheels connected to one side (front) of the rocker. We have to worry about the weight after we know what the final weight will be. I know a light aluminum chair (rod type) can hold a 90kg person! ๐Ÿ˜€ We can further discuss the designs after the wieghts calculations. Remember the MLCAD design? Refine it a bit more depending on two very important properties. 1. Surface bumpiness (spring). 2. Max hight of obstacle it should traverse (design like RB or someother). If we are sure about these two then we can settle on one design ๐Ÿ˜€ ๐Ÿ˜€

Here is a PDF if you want to read a bit more on RB (dont ask me what that math stuff is on later pages!!): https://scripts.mit.edu/~robots/robots/publications/papers/1998_07_Hac_Dub_Bid.pdf


Lasssstly, yes I was being sarcastic about the bump switch bot ๐Ÿ˜€

We will move on to Sensors, Motors and batteried AND the weight calcs very sooon.
raj87verma88
raj87verma88 • Jul 26, 2008
OK I found some PDF files on analysis of Rocker-Bogie and its traction control. The abstract for one is
Rovers will continue to play an important role in planetary exploration. Plans include the use of
the rocker-bogie rover configuration. Here, models of the mechanics of this configuration are
presented. Methods for solving the inverse kinematics of the system and quasi-static force
analysis are described. Also described is a simulation based on the models of the roverโ€™s
performance. Experimental results confirm the validity of the models.
I will mail the files to xHx, Ash, KJ and Gohm.
KINETIC_JOULES
KINETIC_JOULES • Jul 26, 2008
All of the products and devices were found at this website:
GlobalSpec รขโ‚ฌโ€œ Engineering Search & Industrial Supplier Catalogs



Light:

CDS Cells- (Searched using CDS)

Photoconductive Cells:
Photoconductive Cells from Advanced Photonix, Inc.ร‚ยฎ

LED Strip Lighting in Warm and Cool White:
LED Strip Lighting in Warm and Cool White from JKL Components Corporation

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Objects:

Ultrasonic Ranging- (Searched using Ultrasonic Ranging PIC)

Chemically-resistant ultrasoinc sensors:
Chemically-Resistant Ultrasonic Sensors from Baumer Ltd.

RPS-401A-80P Analog Ultrasonic Sensor:
RPS-401A-80P Analog Ultrasonic Sensor from Migatron Corporation

Infrared Reflections- (Searched using Infrared sensors)

micro IRt/c:
micro IRt/c from Exergen Corp.

Radar- (Searched using Radar sensors)
Note: I wasn't sure about this one. This device didn't return the results I was looking for.

Laser Doppler Velocity: Sensors:
Laser Doppler Velocity Sensors from Canon USA Encoders/Optoelectronic Components Group

Video Camera- (Searched using Video Camera sensor)

SONY FCB-H10 High-Definition Color Camera:
SONY FCB-H10 High-Definition Color Camera from Industrial Vision Source

Lumeneraโ€™s OEM and Custom Cameras:
Product Announcement 036/0?fromSpotlight=1&paidFromBricklet=1&fromAreaId=39

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Surface:

Laser Wheel Encoders- (Searched using Laser Wheel Encoders)

Avtron HS35M Encoders:
Avtron HS35M Encoders from Avtron Industrial Automation, Inc.

X Series -Magnetic Encoders:
KX Series -Magnetic Encoders from Admotec Inc.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Location and Orentation:

Odometry- (Searched for using Odometry sensor)
Note: I wasn't sure about this one. This device didn't return the results I was looking for.

Pick-O-Mat Rotary Assembly Chassis:
Pick-O-Mat Rotary Assembly Chassis from WEISS North America, Inc.

Compass- (Searched for using Compass sensor)

OS5500-USG Digital Compass with Depth:
OS5500-USG Digital Compass with Depth from OceanServer Technology, Inc.

360 FULL ROLL COMPASS SYSTEM, HORIZONTAL:
360 FULL ROLL COMPASS SYSTEM, HORIZONTAL from Advanced Orientation Systems, Inc.


Ultrasonic Ranging- (Searched for using Ultrasonic Ranging)

RPS-412A High Accuracy Sensor:
RPS-412A High Accuracy Sensor from Migatron Corporation

Radar- (Searched for using Location Radar)

T24SA - Strain Gauge Acquisition Module:
T24SA - Strain Gauge Acquisition Module from Mantracourt Electronics Ltd.

Accelerometer- (Searched for using Accelerometer)

A30 High Performance MEMS Accelerometer:
A30 High Performance MEMS Accelerometer from Gladiator Technologies, Inc.

Intrinsically safe accelerometers, 786 IS, 787 IS:
Intrinsically safe accelerometers, 786 IS, 787 IS from Wilcoxon Research

Series Acceleration Recorders:
Series Acceleration Recorders from Instrumented Sensor Technology

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Heat:

Thermal Imaging- (Searched for using Thermal Imaging)

IRt/c Non-Contact Temperature Sensors:
IRt/c Non-Contact Temperature Sensors from Exergen Corp.
gohm
gohm • Jul 26, 2008
Wow, that is a fair bit of searching, good job & thanks!
Dexter_Neo
Dexter_Neo • Jul 26, 2008
Cool I have done a similar Project in my final year...I faced a lot of issues in that robo I will be glad to offer any kinda help....................๐Ÿ˜€
That would be greatly appreciated, Dexter ๐Ÿ˜€ What project was it?

@ Kinetic
awesome job! Funny thing to note is that Globalspec sponsors another global engineering online community (CR4).. but I guess we CEans are cooler people *grin*

@Patty
Nice one.. Looking forward to reading the analysis ๐Ÿ˜€

@xhx
I'll try the MLCAD draft with a RB implementation next weekend, along with updating the progress with the Communications module. I just got the Robo Realm vision software working on my laptop, and was playing around with the image processing. Will see if it can stream over Wifi ๐Ÿ˜‰

By the way, I recently found out about a "engineering" linux distro called CAELinux. It has most of the tools we need to simulate and analyze the structure of the CE Bot. Unfortunately its a 2GB download, lol. Might be worth checking out..

CAElinux
xheavenlyx
xheavenlyx • Jul 26, 2008
@Kinetic: Good work! Well, just make a doc of this post and mail it to either Ash or to me (varun@crazyengineers.com). since not many ppl read the entire thread, we have to post these things in celab.tk. You can delete this post from here after we post it in celab.tk

@Patty: Hey, thanks. Mail it and I can do some proper calculations. Hopefully this one will be easier than the one I have checked.

@Ash: Nice. Robo realm is reallly good to understand how to do what we gotta do and then impliment it. Plus, I am rite now looking at the video presentation for CAELinux. Will surely download it (torrent). And let you know.

Do you think we can move on to sensor discussions? The remaining chassis design will be finalized later and we can change/modify it too. (I will also have a look at Patty's pdf). What does everyone think?
KINETIC_JOULES
KINETIC_JOULES • Jul 26, 2008
You're welcome. . . it didn't format right when I copied and pasted. I told you, I like to do research.
Dexter_Neo
Dexter_Neo • Jul 28, 2008
@Ash.....

the project title was Mine Rescuer........
The Aim was to reach at the opening of the mine by using an Light detection aolgorithm.and whatever the rescue path robo takes,it stores that path in memory and later on we can get that resue path by connnecting the robo to pc.we were storing the path in the memory in R,theata format means distance angle format.Then by using serial communication we get an image of the path taken and after wards we can send the rescue team .Moreover the robo was capable of transmitting live images and videos.it was enabled with automatic triggering system.and we used 6 geared DC motors .we used 12V 2200 mah battery.it was enough to drive the prototype at least.apart from it we had proximity detection also .


Now i implemented a prototype of something i thought but in CEbot i am not clear whether its a prototype or a full fledged robo itself.

I am not clear enough with the aim also..
MaRo
MaRo • Jul 28, 2008
May be I'm missing something ๐Ÿ˜’

What Flying bot? Decreasing weight and increase flexiblity

May be this can be useful if you want to decide the engine : O.S. Engines Home Page
xheavenlyx
xheavenlyx • Jul 28, 2008
@Dexter: The project you did was wonderful, but why do you call it a prototype if its doing everything that you intended it to do? Just wanna know. And secondly, your concerns are well founded about the exact purpose of this bot. Presently, the 2 main things are (there are more that Ash can tell) are:

1. Be fully modular. Meaning we can remove and replace any part. We are hoping this is possible for the chassis too depending on terrain. So it can be configured to be anything we want it to be. Remember, this is VERY ambitious but we do hope to make it as much modular as possible without reducing its productivity.

2. The first design we will concentrate on will be for rugged terrain and be able to map out the area for obstacles.

Lastly, what are your suggestions and thoughts?

@MaRo: No its not a flying bot and we wont be using glow engines.
Ah, that could very well be a future project! Since we are currently using 802.11g for communications, we could have a mesh network of robots working together, with the host computer acting as an access point. The flying bot would certainly enchance the mapping function. Maybe a "helicopter" sort of device that can hover near the CE Bot, so both can complement each other. Too ambitious? It'll certainly give a long term application to the efforts we are doing.

Back to the CE bot, we could spend another week on the chassis before moving on to sensors. I'll do what I can using MLCAD this weekend, and after some discussions, we can move on to sensors. They can still run in parallel, I suppose.
KINETIC_JOULES
KINETIC_JOULES • Jul 29, 2008
Where did a flying bot come into the picture?

@ xhx: Did you get my E-mail? I sent you that research txt document.
MaRo
MaRo • Jul 30, 2008
EDIT:I meant "What about a Flying bot? Decreasing weight and increase flexiblity"

OK, it was just my opinion that it can decrease a lot of headaches designing and calculating the bot motion.
KINETIC_JOULES
KINETIC_JOULES • Jul 30, 2008
MaRo
EDIT:I meant "What about a Flying bot? Decreasing weight and increase flexiblity"

OK, it was just my opinion that it can decrease a lot of headaches designing and calculating the bot motion.
Oh. . . I'm sorry! I just misread a lot!
vivekji
vivekji • Aug 1, 2008
Well my dear CEans let us stop talking and start working on it

We'll start with a simulation bot

Microsoft's Robotics Software will be ideal for it๐Ÿ˜
KINETIC_JOULES
KINETIC_JOULES • Aug 1, 2008
vivekji
Well my dear CEans let us stop talking and start working on it

We'll start with a simulation bot

Microsoft's Robotics Software will be ideal for it๐Ÿ˜
Well. . . It's kind of precautionary. That's what we're doing. . . working on it.
We can't just WORK on it without actually knowing what we are doing. And that's what we are doing. We can't just work on the bot without doing research first. You need designs and tons of research before you even begin to work on it! It's like putting a desk together without the instructions. You may think you know what you're doing, but in the end, you realize that there are excess parts that were needed in building the desk, and have to start all over; when really, you should have used the directions in the first place. And that's simply the case here. We must take precautionary measures before we start to build the bot.
I'm not fussing at you, I'm just simply saying that we ARE working on the bot. I really do appreciate your interest in the CE Bot team, though! Do you want to be part of the team? If so, welcome to the team!
Ashraf HZ
Ashraf HZ • Aug 1, 2008
Thanks for that, vivekji! I checked it out.. the simulator is very interesting indeed. Have you used it before?

Here's the link to the main robotics page
Microsoft Robotics

Here's a screencast of the actual 3D simulator feature. Pretty neat..
Microsoft Robotics Studio: Simulation

Xhx, its worth a look. Its 3D! ๐Ÿ˜€

By the way, I tried out Phun.. its super fun! ๐Ÿ˜› My fav example was the catapult, hehe. Oh, you can try fabricating a shock absorber using the spring tool. Increase its strength to 1.0 ๐Ÿ˜€ Try making a slot thing so the spring movement will be linear.

[EDIT]
vivekji, we are indeed having progress. However, like Kinetic said, a lot of research still needs to be done ๐Ÿ˜€ Please check out celab.tk for our progress.

At the moment, we still need to see the feasibility of the Rocker Bogie frame. The MS Robotics Studio looks to be a compelling software to use, but I hope we don't have to spend a lot of time to learn how to use it. It would be great if you already have an experience with it.. perhaps you can simulate some simple scenarios? Use xheavenlyx's phun videos to get an idea.
Hello guys!
Great effort here and feel sorry for being a little late .....
I have some ideas that I must share:
1. Ackerman drive has its problems..... Why not apply Ackerman drive to ALL three pairs of wheels?
We can rack & pinion all three pairs of wheels with a single steering motor, for a truly Omni-Directional drive. This will result in a square platform with great stability.
2. Gyro assist drive system. This can compliment the accelerometers as also independently adjust the wheel torques.
3. I have some misgivings about the Rocker-bogie frame......We have tried a couple but were'nt satisfied with the system.

May be late here, but my .2ps , all the same. Its great to be here with all of you!!
KINETIC_JOULES
KINETIC_JOULES • Aug 1, 2008
docel
Hello guys!
Great effort here and feel sorry for being a little late .....
I have some ideas that I must share:
1. Ackerman drive has its problems..... Why not apply Ackerman drive to ALL three pairs of wheels?
We can rack & pinion all three pairs of wheels with a single steering motor, for a truly Omni-Directional drive. This will result in a square platform with great stability.
2. Gyro assist drive system. This can compliment the accelerometers as also independently adjust the wheel torques.
3. I have some misgivings about the Rocker-bogie frame......We have tried a couple but were'nt satisfied with the system.

May be late here, but my .2ps , all the same. Its great to be here with all of you!!
We're glad to have you a part of the team! Thank you!
Ashraf HZ
Ashraf HZ • Aug 1, 2008
docel
Hello guys!
1. Ackerman drive has its problems..... Why not apply Ackerman drive to ALL three pairs of wheels?
We can rack & pinion all three pairs of wheels with a single steering motor, for a truly Omni-Directional drive. This will result in a square platform with great stability.
2. Gyro assist drive system. This can compliment the accelerometers as also independently adjust the wheel torques.
3. I have some misgivings about the Rocker-bogie frame......We have tried a couple but were'nt satisfied with the system.
Thanks for the input, docel!

1. We have two options for steering: Ackerman and independent servos. I believe true omni directional drive is possible only with the latter, as you have a limited steering angle using Ackerman. (see this post: https://www.crazyengineers.com/forum/ce-labs/2312-ce-project-ce-bot-5.html#post13795). We'd have to weigh the pro's and con's for each system (eg weight, cost, implementation difficulty). Personally, independent servos for each wheel is a good option, since we can control each wheel on its own. But then again, the more motors we are adding, the more strain on the power supply. We are targeting an operation time of at least ONE hour. More than that would be ideal.

2. Oh, first time I heard of that! Sounds cool ๐Ÿ˜€ Can you describe more about it?

3. Indeed, its not really commonly used. However.. if we can pull it off, it be a very versatile frame. Anyhow, whatever we choose wont affect the design of the rest of the robot; CE Bot will be designed modularly, so each major module can be interchanged. This Rocker-Bogie platform is the "locomotion module", can be hot swapped with other platforms such as tracked, a stationary stand, or even a boat hull to traverse across water. Just "plug 'n play" ๐Ÿ˜‰

We'll perform a number of simulations and continuous research on the Rocker Bogie frame. There are some materials on it on the CE Lab website: celab.tk

What difficulties did you face when you tried to implement it? Perhaps they can be overcome this time? Your past experience will really help us out ๐Ÿ˜€

Alright, briefly on other things.

Communications

I propose we really stick to using 802.11 wireless technology on the long run. Networked robots will provide a lot of potential for other uses, and when MaRo mentioned Flying Bots, it hit me that we can have collaboration with future robotic projects.. or even other robots done by other groups that has a network node. Very similar to the concept used in Soccer Bots ๐Ÿ˜€ Each robot would have its own IP address, etc etc. IP Robots can theoretically be controlled from anywhere in the world with a WiFi AP!

The main problem would still be power consumption and range. However, that can overcome with diligent research!

Misc
I was thinking about a more expansive name for the project. How about.. CE R[sup]3[/sup]? Crazy Engineers Research & Recon Robot ๐Ÿ˜›
Dexter_Neo
Dexter_Neo • Aug 1, 2008
@Ash
hmm 802.11 R u refering to WiFi Protocol ? anyway it's a good idea to use it .if we r implementing a prototype a simple ASK transciver would also do the job.Coz u know we get these transciver readily.And Idont know abt the implementation of wifi.

And R we done with chasis design........

ASH I would like to comment that we r missing the scope of the RObo.Limit the scope of the robot.Otherwise we would keep on discussing and u know we r blessed with cool ideas so it will waste a lot of time.So limit the scope and start the implementation.Enough of research work I guess .And we should prototype it first then once we get it sponsered from any company we will go for the actual implementation there we can apply our knowledge........
Ashraf HZ
Ashraf HZ • Aug 1, 2008
Yep, the scope is indeed limited already:
- CE Bot will perform data collection using sensors
- It'll have a chassis that can go over rough terrain
- Transmit data through a wireless to a computer nearby

We already know what we want and need. What we are discussing now is HOW to implement it. The rocker bogie concept can't be done immediately without researching enough information on it. Xhx has already begun simulations. Remember, things are being done in parallel: Programming, Communications Testing, and Robot Design. Sensor discussion is coming up soon.

The reason why it seems we are "wasting time" is because we have lots of uncertainties on the implementation. Xhx has made a very good flowchart on what we need to discuss:
https://www.crazyengineers.com/forum/ce-labs/3465-ce-project-ce-bot-part-two-2.html#post17066

We'll need to discuss on possible solutions, evaluate them, and filter down to a final solution.

Other thing is.. we dont have anyone personally taking charge of the Robot as their project, and dedicating their full time. I dont think any of us are doing this as a final year project. Also, we do not have Project supervisors to guide us. All of us are doing this by ourselves in our free time: from planning and so on. Everything was started from scratch! It takes lots of discussions to decide the things we need to do.. and something like this takes lots and lots of research. Have you read the objectives stated in the CE Lab website? We'll take things step by step ๐Ÿ˜€

Regarding sponsorship, thats already being initiated. Big K and Mayur is working hard on that.. but we'll need to create a very good proposal first. That'll include cost estimates, etc.

I think we are doing ok. It usually takes a whole semester to do research on a project.. thats keeping in mind that you spend a lot of time everyday, discuss things with supervisors ๐Ÿ˜‰ Once we get the research done, and more active CEans are involved, the later stages can be completed quick.
pkv_raman
pkv_raman • Aug 2, 2008
Iam a new member of crazy engineers.The idea of the bot is fascinating.I would like to contribute.praveen.
bayazidahmed
bayazidahmed • Aug 2, 2008
Can we have dual mode in steering?

Confused?

We'll attach four independent servos but will design the gear system in such a way that it should be able to work with two servos also.
Advantage? We can enable the other two servos only when we need them. Rest of the time they will be disabled.

If we like this idea then we can go for triple mode. 1 servo (usefull if we are going straight for a long stretch), 2 servos, and 4 servos. We can also program the controller (I think its decided that we are going to have an independent controller for the drive system) to play around with the servos, we just give the command and the controller will decide how many servos it needs. Example: I give a command to go straight, the controller will use only one servo, If i give a position in latitudes and longitudes (if we are using GPS) the controller will make use of two servos and steer to the desired position, or If i give a command to take a tight left/right the controller can enable all the four servos and take the turn.

Objective achieved: Saving lots of power using simple and smart programming. ๐Ÿ˜Ž

???
ash
Also, we do not have Project supervisors to guide us.
...be glad to Supervise this Project......!
gohm
gohm • Aug 3, 2008
very cool idea. How will this fit in to space/weight restrictions of the design on the bot chassis? how would you incorporate a failsafe structure to limit a failure locking one of the several servos in a turn thus crippling the directional control?

bayazidahmed
Can we have dual mode in steering?

Confused?

We'll attach four independent servos but will design the gear system in such a way that it should be able to work with two servos also.
Advantage? We can enable the other two servos only when we need them. Rest of the time they will be disabled.

If we like this idea then we can go for triple mode. 1 servo (usefull if we are going straight for a long stretch), 2 servos, and 4 servos. We can also program the controller (I think its decided that we are going to have an independent controller for the drive system) to play around with the servos, we just give the command and the controller will decide how many servos it needs. Example: I give a command to go straight, the controller will use only one servo, If i give a position in latitudes and longitudes (if we are using GPS) the controller will make use of two servos and steer to the desired position, or If i give a command to take a tight left/right the controller can enable all the four servos and take the turn.

Objective achieved: Saving lots of power using simple and smart programming. ๐Ÿ˜Ž

???
KINETIC_JOULES
KINETIC_JOULES • Aug 3, 2008
Wow. . . everything that was just said went right over my head!
Ok, here are some points to ponder:
1. The dimensions of a vehicle is determined by the purpose and the necessary mechanisms.
I'm not too sure if the size was fixed - think I read "Magazine" size somewhere- and if ALL the things can be fit in.
Also, a Laptop is decided to be the brain. This will generally decide the dimensions.
2. The Power unit will be the next thought.
This is decided by the Drive/ Propulsion / Actuators and the Electronics.
3. The Size will restrict the Propulsion/ drive mechanics.
Most types of Drives are NOT possible or necessary for a given dimension, no matter how exotic or breath-taking they may be.
For example, a laptop will necessitate a foot print of 1.5 times its size.
The Wheel diameter will then be a function of the platform footprint.
If you consider a 6 wheel drive, then you have the dia. in front of you. With such small wheel diameters, it is not possible to have exotic drive mechanisms in place for it to be either practical or efficient. In fact the mechanisms will need to be simple if they have to be efficient.

:arrow: Now, this is a viscious cycle. It is essential that the objectives are fixed ( to a large extent) along with variants so that Plug-in Modules may be designed.

4. Any vehicle can be made simple and efficient with some very basic mechanisms. A 4WD large diameter wheeled vehicle will serve a lot of difficult terrains. The problem is it might turn turtle, as it exerts a push-push traction, unless it is controlled by attitude sensors.
If the path is 'very' difficult, then it will avoid that patch and find a much easier way around!! Thats what the Vision and Sensor systems are for , anyway.

Ash:

Gyroscopes will sense any change in direction. If I put a gyroscope on a vehicle, it will try to maintain the vehicle in the same attitude throughout. If the vehicle changes its orientation, the Gyro will output an error voltage. There are x,y,z Gyros. The Gyro output can be used to 'correct' the change. In a nutshell , the Gyro will sense Tilt angles in the x, y & z planes and output proportional voltages . These voltages can be used as feedback signals for attitude correction.
I proposed the idea of using these signals as a dynamic tilt feedback to control motor torque, as in navigating steep gradients etc.,
Ashraf HZ
Ashraf HZ • Aug 4, 2008
Great points, docel!

Size
I mentioned "magazine" once or twice initially.. but have recently proposed having the payload size of an A3 paper. So whatever locomotion system will use, the total footprint would be larger than A3 (but not less). Should be enough to fit the rest of the subsystems. Of course, I'm only using A3 as an arbitrary figure for guidance.. exactly final dimensions may differ.

The laptop would be stripped bare, with only its system board remaining. Screen, keyboard, etc, will be disconnected. There is a VGA port, so we can still connect a monitor for debugging purposes.

You are right, all this may seem to be a vicious cycle, haha. But, we could treat it like a feedback system. Pick the most significant aspect, and use the rest of the components to fine tune the final dimensions. We must get used to changing the sizes until we reach "steady state".

Modularity
Indeed, the design of Plug-in Modules (I like that name!) should be consistent. There should be a standard connection and size constraints so each component can fit together with ease. The exact dimensions can be decided later, but we may need to show some concepts or visualization on how they will be connected.
gohm
gohm • Aug 4, 2008
It can also be designed in shape and weight so that if it flips over it will also roll right-side-up, give the space. Also, are we still adhereing to the original proposed mission functions for this bot? If so that will of course dictate all aspects of the design. A "sticky" post listing all things finalized that one person could update would be a big visual help. I have not noticed that, sorry if there is. So that we know what has been resolved, what remains & how to design other compontents around them.
Ashraf HZ
Ashraf HZ • Aug 4, 2008
gohm
It can also be designed in shape and weight so that if it flips over it will also roll right-side-up, give the space. Also, are we still adhereing to the original proposed mission functions for this bot? If so that will of course dictate all aspects of the design. A "sticky" post listing all things finalized that one person could update would be a big visual help. I have not noticed that, sorry if there is. So that we know what has been resolved, what remains & how to design other compontents around them.
Damn.. just typed a very very.. VERY long post detailing our progress for each module, and I lost it. I need to destroy something to release my stress.

๐Ÿ˜ก

Btw Gohm, duly noted. The first post of this thread will contain our progress/objectives. I'll update it later.
gohm
gohm • Aug 4, 2008
I feel your pain, sorry. I've also type up fabulous posts full of inciteful detail only to have it disappear somehow when you click on submit. The first time I thought I was saved by the back button... wrong! laugh

ash
Damn.. just typed a very very.. VERY long post detailing our progress for each module, and I lost it. I need to destroy something to release my stress.

๐Ÿ˜ก

Btw Gohm, duly noted. The first post of this thread will contain our progress/objectives. I'll update it later.
xheavenlyx
xheavenlyx • Aug 4, 2008
====

EDIT: Shoot, I typed the below post after looking at the last page. I just came upon the 6th page rite now! anyway, everything here is still valid, but Id like to reply to Docel's post. He has given some points to ponder over. Thats at the end of this post.

====

When me and Ash first proposed this project, I was weary that it might be too difficult to control if it gets bigger. And I agree with Ash that we need a Supervisor for this project.

Secondly, I have been reading the thread for about 4 days now. I see is a LOT of great ideas being thrown about and not processed. And really good ideas that too.

So to reduce this drainage of creativity and missing on the important points in confusion we must move in an organized manner. We will do that from now on.

More importantly, I want to ask everyone (by everyone I mean who are familiar with the project), are you ok with me heading the project?

=======

Now, what we can do:

1. We can pause the drive system and chassis discussions for now as it is. Finally we will (should) have two designs put together. Interchangeable if possible. Still, the final design can be done later.

2. Why later? We will finalize the sensors and the processors and battery and hence we will obtain an approximate weight of the payload. This is VERY VERY important for final design of the chassis.

====================

@Gohm and Ahmed!: Your idea is good, but veryyy complicated. From what I understand, we have 4 servos, but use only 1/2/3/4 depending on use? Well IMO, servos will be used for 3 directions on the x-y plane;

Forward/backward and Right and Left. On Forward and backward we dont use any servos except a few times for direction correction. For Left or Right we use "all 4" for a small amount of time. The bot turns on its place no angular motion in the equations. Later we might need to look at problems if the wheel gets turned due to friction, servo must be self centering (very easy).

=========

@Docel: Thanks for you input. Ash has given good inputs to your idea and thanks for reminding us to use Gyro assisted drive (Accelerometer used to find the exact movement, orientation, pitch and roll). I think accelerometer HAS to be in the drive loop. Its very important!

Docel, in some of my previous posts I had posed several videos showing Rocker Bogie being used in LEGO bots [LINK]. They didnt seem that "exotic", plus we will consider other chassis types too specially large wheeled AWD. And moreover as you said, we realllyyy need to start looking up the types of sensors, batteries (NiMh or Li-ion 12/24V) and motors and motor drive and processor casing and THEN we can know the weight, and then we can finalize on the chassis! So as you said:

The dimensions of a vehicle is determined by the purpose and the necessary mechanisms.
is absoluetly right!!!

So as stated, next, we will be looking at sensors and everything else.

@MaRo: Flying bot, sorry I didnt understand you in the last post. A flying bot with a webcam is my dream, ๐Ÿ˜€. We will surely take it on the next project. It will complement with the CE Bot well.

@Ash: This thing is going pretty fast now. We have to get organized. Ash, we will pause chassis design for now, any research you are doing, directly email it to me. Your test with Wifi must be going on. It should ๐Ÿ˜› As I said before we will have 2 designs for the chassis. Rocker-bogie (maybe, still in consideration) and one more. Again, Docel's point, we can go in circles, after we start with sensors and motors and their sizes.

As for the name, CE R[sup]3[/sup]: Crazy Engineers Research & Recon' Robot is really good ๐Ÿ˜€. But can it be more internet text-box friendly like CE R cube or something? But logo will be: CE R[sup]3[/sup]
gohm
gohm • Aug 4, 2008
As they would say in Middle Earth.. "my bow bends to your will sir!"
Which would be a yes vote xheavenlyx. This project greatly needs a project leader. I also agree the multi servo idea is too complicated for our current use, though a good idea.

another option for the logo (we all know that is what is most important of the project, laugh) would be involving CE tri R or CEtriR or maybe CE triR.

I am still in favor of a central motor powering all six wheels via a chain drive system. The 6 direct drive motor idea is very cool however it makes it more complicated and has some other minor drawbacks. Maybe on CEbot2.

We will also need to decide if it will contain a manipulator arm or blade etc. (to grasp objects-like something that could identify a victem- or move things out of the way-debris blocking the tunnel- or carry items to someone like a water bottle or supplies. This will also effect weight, cargo capacity and battery usage.
KINETIC_JOULES
KINETIC_JOULES • Aug 4, 2008
I'm very confused here. We went from progressing fairly slow to speeding everything up and I'm confused. Please, someone explain to me what is going on!
Ashraf HZ
Ashraf HZ • Aug 5, 2008
KINETIC_JOULES
I'm very confused here. We went from progressing fairly slow to speeding everything up and I'm confused. Please, someone explain to me what is going on!
Ah, we are trying to organize ourselves. We are having lots of good ideas being thrown around, but the actual implementation of ideas doesnt seem to have a direction. Look out for the updated post at the beginning of this thread, soon ๐Ÿ˜€ Hows the designing going? Oh, can you try to design a logo for CE R[sup]3
[/sup]? ๐Ÿ˜€
gohm
I am still in favor of a central motor powering all six wheels via a chain drive system. The 6 direct drive motor idea is very cool however it makes it more complicated and has some other minor drawbacks. Maybe on CEbot2.
Perhaps that'll be the second choice for our locomotive system? For sure we cannot implement a chain drive system in the Rocker Bogie frame, so we'll need a different frame. We can design them side by side like xhx said so both can be compatible with the rest of the modules. Of course, only one will be chosen for the final fabrication.. unless we get more resources and produce two instead ๐Ÿ˜‰
We will also need to decide if it will contain a manipulator arm or blade etc. (to grasp objects-like something that could identify a victem- or move things
out of the way-debris blocking the tunnel- or carry items to someone like a water bottle or supplies. This will also effect weight, cargo capacity and
battery usage.
You are right.. I believe a manipulator arm will be implemented. Its usually called a "gripper", and its design will need to be thought out just like the
chassis. I didnt give much thought to it last time, because I wasnt sure if those things will be a seperate module or part of an existing module. What should be good cargo weight? 10kg? How heavy are the obstructions CE R3 will need to move? We have to be realistic.. I guess it can lift some branches and small rocks if it cannot traverse over it.

xheavenlyx
Now, what we can do:

1. We can pause the drive system and chassis discussions for now as it is. Finally we will (should) have two designs put together. Interchangeable if
possible. Still, the final design can be done later.

2. Why later? We will finalize the sensors and the processors and battery and hence we will obtain an approximate weight of the payload. This is VERY VERY important for final design of the chassis.
Oh, I get you bro. If too much focus is placed in the chassis, we'll go nowhere with the rest of the modules. But, instead of pausing it, we can still work on concept designing.. like what Kinetic is doing. Other things, like the exact dimensions and dynamics, we can finalize it once the payload is worked out.
@MaRo: Flying bot, sorry I didnt understand you in the last post. A flying bot with a webcam is my dream, . We will surely take it on the next project. It
will complement with the CE Bot well.

@Ash: This thing is going pretty fast now. We have to get organized. Ash, we will pause chassis design for now, any research you are doing, directly email it to me. Your test with Wifi must be going on. It should ๐Ÿ˜› As I said before we will have 2 designs for the chassis. Rocker-bogie (maybe, still in consideration) and one more. Again, Docel's point, we can go in circles, after we start with sensors and motors and their sizes.
Yep, owners of RC planes (I think there was a thread about it on CE loooong time ago.. Biggie is a big fan of them ๐Ÿ˜›) implements wireless cameras in them. However, the reception is not so great since there is inteference with RC components and motors. You'd need powerful transmitters.

Regarding the current Communications testing for CE R3, I added some experimental objectives on the CE Lab website, under the Communications page at the bottom. They are still "pending" ๐Ÿ˜› Don't worry, the testing is under way. I'm involved in another uni project which requires wireless communications (and imaging), so there is no conflict of interest *grin*

In one of my labs, one of my groupmates proposed to do a project on Light Wave Communications. Thats certainly something we'd want to implement on CE R3 one day ๐Ÿ˜€

Batteries
Li-on would be the perfect candidate.. if we had the funds. NiMh will be a good alternative, but for motors we'll need to SLA.. or Sealed Lead Acid. Motors
consumes current like anything, and SLA can provide enough amps for that. But they are heavy. We have a "battery" page in CE Lab already. Actually, we already have lots of info on CE Lab.. we all must read through it! Me, xhx and Patty will try updating stuff there.

At first I thought of having a seperate battery module.. but I think we should just embed specific battery technologies according to their application. If there is a locomotion module that requires LOTS of power, it'll have its own type of battery pack. For a low consuming module, it'll also have its own pack.

Xhx, perhaps we should delegate tasks according to module? I remember you asked last time on who would take which subsystem, according to the chart you made a few pages back. But havent had much takers ๐Ÿ˜›
Ok, I'll try updating the first post now. Still got lots of things to say though.. will wait for comments first.

Last but not least.. xhx, we are perfectly fine with you leading the project. We believe in you, and support you all the way ๐Ÿ˜€
MaRo
MaRo • Aug 5, 2008
Boycotting the Land bot
Ashraf HZ
Ashraf HZ • Aug 5, 2008
MaRo
Boycotting the Land bot
๐Ÿ˜›

Actually, you dont have to boycott it entirely. We could certainly have a locomotive module that flies. Whatever system module we design can be used in ANY locomotive system, as long as we standardize the connections.

MaRo, try researching on aeronautical materials? Perhaps there is an existing RC plane we can use to adapt to CE R[sup]3[/sup]. Designing a new plane is too much at this stage.. all those equations and wind tunnel testing *faints*

This talk of modularity might confuse CEans. I believe the crux of the CE Bot (or R[sup]3[/sup]) is the laptop module itself. We can connect anything to it. Whats important is that we make sure it can connect to various things, and process a wide range of data. Thus, the software on it will be adaptable and highly programmable. Thats why the robot brain being the laptop is very important. This modularity and multifunctionality is the main objective. Another important aspect is the ability to function with other objects.. hench the networking aspect of it. This is why the 802.11 protocol (or other Internet technologies) is desirable.

In that light, one proposed mission is the terrain mapping/sensor collecting over rough terrain. With that mission, we design the rest of the modules.

Different missions will require different modules. But we'll focus on one thing at the time.

You guys understand? Maybe I should draw a diagram to express better.

[EDIT]
Updated the first post of the thread a little. By the way, we might need to start Part Three of discussion.. posts have already reached over 100! Lets wrap up on things and start fresh with sensor discussions on a brand new thread.
KINETIC_JOULES
KINETIC_JOULES • Aug 5, 2008
ash
Ah, we are trying to organize ourselves. We are having lots of good ideas being thrown around, but the actual implementation of ideas doesnt seem to have a direction. Look out for the updated post at the beginning of this thread, soon ๐Ÿ˜€ Hows the designing going? Oh, can you try to design a logo for CE R[sup]3
[/sup]? ๐Ÿ˜€
Well. . . I'm not sure what CE R[sup]3[/sup] is. . . can you tell me?
And I haven't been working on the designing. . . (sadly) because I'm not sure what to do at the moment.
raj87verma88
raj87verma88 • Aug 5, 2008
KINETIC_JOULES
Well. . . I'm not sure what CE R[sup]3[/sup] is. . . can you tell me?
And I haven't been working on the designing. . . (sadly) because I'm not sure what to do at the moment.
It was a name suggested by xheavenlyx
As for the name, CE R3: Crazy Engineers Research & Recon' Robot is really good :smile:. But can it be more internet text-box friendly like CE R cube or something? But logo will be: CE R3
So many ideas have come in the last 10 days. Was busy so could not contribute much. Will be reading all the long posts thoroughly before adding something.
Goodt going everyone.
KINETIC_JOULES
KINETIC_JOULES • Aug 5, 2008
raj87verma88
It was a name suggested by xheavenlyx


So many ideas have come in the last 10 days. Was busy so could not contribute much. Will be reading all the long posts thoroughly before adding something.
Good going everyone.
Okay. . . Umm. . . I still am not sure what to do! I'm a little clueless lately. Got a lot of things going on.
Ashraf HZ
Ashraf HZ • Aug 6, 2008
Still work on possible designs for CE Bot (or proposed name: CE R[sup]3[/sup].. whatever floats your boat). Do draft a design with the rocker-bogie frame ๐Ÿ˜€

If you want, try designing a logo for the project too ๐Ÿ˜‰

A slight warning here: progress might be slowed down a bit as we try to reorganize the ideas. We need to build our ideas from the foundation, so that we have a solid understanding on the objectives. However, please do contribute any additional ideas you have ๐Ÿ˜€

Remember, we have the laptop as the constant. Any and everything will be designed and constructed around that. Hows that for a prime mover? ๐Ÿ˜‰ The key is modularity, as Ive discussed briefly in my previous post.
Good thinking!

ash , xheavenlyx :

I forgot to answer the query about my many Rocker-Bogie experiments.

1. It is OK when the going is rocky. The problem is in muddy terrain where it ploughed into the mud although this behaviour was solved, to some extent, using large wheel width

2. It did not take too easily to small plants and shrubbery, which caught in between the wheels. There are too many 'catches' that trap plants and get clogged in the design.
One of our solutions was to place shields but wasnt very helpful. I even converted one with a cutting shear in front ......it wound up like a RoboWarz candidate!!
Just a word of caution, thats all.
I can make one of them in a days time, if you want to fool around with it. You guys can control the thing over the net.
xheavenlyx
xheavenlyx • Aug 7, 2008
Docel, that was extremely valuable information!! Thanks a lot. I think after this we might be concidering alternatives.

Docel, is it possible for you to get the video of the Rocker Bogie design?? It would be awesomely helpful. As for you making a bot and we controlling it online, it seems very tempting, but I dont want you to spend a lot of time building something just for that. However, if you DO have a bot pre-built then you can connect it to the net for us ๐Ÿ˜€
KINETIC_JOULES
KINETIC_JOULES • Aug 7, 2008
ash
Still work on possible designs for CE Bot (or proposed name: CE R[sup]3[/sup].. whatever floats your boat). Do draft a design with the rocker-bogie frame ๐Ÿ˜€

If you want, try designing a logo for the project too ๐Ÿ˜‰

A slight warning here: progress might be slowed down a bit as we try to reorganize the ideas. We need to build our ideas from the foundation, so that we have a solid understanding on the objectives. However, please do contribute any additional ideas you have ๐Ÿ˜€

Remember, we have the laptop as the constant. Any and everything will be designed and constructed around that. Hows that for a prime mover? ๐Ÿ˜‰ The key is modularity, as Ive discussed briefly in my previous post.
Okies! So. . . What exactly is CE R[sup]3[/sup]? Give me some examples of what to design.
Ashraf HZ
Ashraf HZ • Aug 8, 2008
CE R[sup]3[/sup] is short for Crazy Engineers Research and Recon Robot. Its only a suggested name for the CE Bot, so it can change anytime. Anyhow, don't let the new name confuse you. Its the same project as what we have been doing all along.

You've seen what a rocker-bogie frame looks like, yes? Can you try to do a 3D design of it on Google Sketch? Just one or two will be alright.

@ Docel
Thank for the info! Echoing what xhx said, a video of your experiments would be greatly appreciated ๐Ÿ˜€

Can you tell us about how it can be controlled through the net? For example, what equipment, software and protocols used. We may want to try something similar in the CE robot in the future ๐Ÿ˜€

As for muddy terrain, maybe can use the original 6 wheel platform?
KINETIC_JOULES
KINETIC_JOULES • Aug 8, 2008
ash
CE R[sup]3[/sup] is short for Crazy Engineers Research and Recon Robot. Its only a suggested name for the CE Bot, so it can change anytime. Anyhow, don't let the new name confuse you. Its the same project as what we have been doing all along.

You've seen what a rocker-bogie frame looks like, yes? Can you try to do a 3D design of it on Google Sketch? Just one or two will be alright.
SURE THING! You got it! So. . . *marks on to do list (aka a pile of sticky notes)* I make a logo for CE R[sup]3[/sup] and work on a 3D design of the Rocker-Boogie frame? Alright! Can do!
bluegeek
bluegeek • Aug 10, 2008
hi there....

I recently joined this group..the whole idea is freakingly good!!

I am not a big robot buff but have a bit of programming skill that may come in handy for you guys....

Can anyone brief on the whole project in a short type....

Waiting for your reply's!!
xheavenlyx
xheavenlyx • Aug 10, 2008
I have been out here, mainly due to my health. We will get back in speen in a day or two and dude above me ^ (sorry to lazy to check which page I had seen your new post ๐Ÿ˜€ welcome to CE Bot or CE Rcube.

I recomend you go through the main pages and the ones that interest you:: celab.tk
Hi ash, xheavenlyx !

Sorry folks ๐Ÿ˜”

I cannot share those videos due to Copyright and confidential status; they have not matured for publication yet. They are my students' projects, under my guidance and mentored for specific purposes. There are some innovative changes in each of the Rovers and are not an exact replica of the original Rocker-bogie configuration and i dont like them to become prior-art just now.
It is different, if i make a new one independent of these and with a specific purpose, relevant to the CeRReconRover.
KINETIC_JOULES
KINETIC_JOULES • Aug 11, 2008
Sorry I've been out, guys! I was away with my work, but I'm back guys. I have this week to work on those designs before school starts. . . it starts on the 19th for me (Which is like next Tuesday) So. . . I'll be getting what I can done.
xheavenlyx
xheavenlyx • Aug 12, 2008
Ok, no problem, I understand you conviction. Since these are student projects you cannot share them ๐Ÿ˜€. Generally, I get very confused with re-inventing the wheel, since its difficult to use whats patented, BUT I've heard its ok to use a patent if you add/improve the patent and credit the original patent holder. So, if you think the design you have used can be helpful then I hope you consider sharing it, because we will not use this commercially.

Anyway, we will have 2 suspension/chassis designs for CE Rcube. We can design them side by side or later in the project. One Rocker-b, and the other, large 6 wheeled drive.

Coming up, we will concentrate on Sensors, vendors and their input/output (IO) properties. Later, on physical placement with respect to processor/payload and power/physical connectors (wire) requirements.

I will design a presentation and post it here, we will follow an organized way. docel, if you have any suggestion regarding this please share it with us as you are an experienced designer.
bluegeek
bluegeek • Aug 14, 2008
Looks like we are not considering the friction part of the rocker-bogie design...in tougher terrains rocker bogie deisgns usually fails....similar to a car in sand...

Anyways if anyone has made any draft of the rocker bogie design can they share it please...i can take a look at it...
KINETIC_JOULES
KINETIC_JOULES • Aug 14, 2008
bluegeek
Looks like we are not considering the friction part of the rocker-bogie design...in tougher terrains rocker bogie deisgns usually fails....similar to a car in sand...

Anyways if anyone has made any draft of the rocker bogie design can they share it please...i can take a look at it...
I'm going to start working on it. . . I've just been very busy lately! But please, bare with me as I try to get it done!
xheavenlyx
xheavenlyx • Aug 17, 2008
I have been away from the project for a few days. I am working on the presentation, plus have one more important project, so a little busy.

@Bluegeek, there are a few papers on Rocker bogie case studies online (Speacially, NASA's rovers which use rocker-bogie), and some have been posted on celab.tk (our project website) links are end of post. It would be helpful if you can read these and do some studies. I am reading one file, but I have to get a bloody print out to do it faster.

Actually NASA did have the traction problem, but they solved it with wider wheel and straight groves on the wheels for more grip.

1. Traction Control of a Rocker-Bogie
Field Mobile Robot
(Expert read) : https://sites.google.com/a/crazyeng...-locomotion/2005_V10_No4_6.PDF?attredirects=1

2. ANALYSIS AND SIMULATION OF A ROCKER-BOGIE
EXPLORATION ROVER
(short, easier to read?): https://1572850514417064523-a-crazy...motion/1998_07_Hac_Dub_Bid.pdf?attredirects=0
Sorry, I've also been busy with stuff ๐Ÿ˜”

Btw xhx, I'm planning to get my rotary set this weekend! Can't wait! not Dremel, of course ๐Ÿ˜› Theres a cloned version of the Proskit rotary set. Should last me for the duration of my studies ๐Ÿ˜€

Back to CE Bot.. hopefully next month I'll start constructing the Omni-directional antennas for the 802.11 module. I'll try getting hold of an SWR meter from the lab soon. I trust you guys with the decisions for locomotive module.. I dont think I have time to contribute to that bit at the moment ๐Ÿ˜”
MUAHAHAHA! I just got my rotary drill last week!

.. its a clone of the Proskit one, called CT-800. Check here:
IPmart.com - Super Drill Set CT-800

Its cheap, but very hard to find in my city. Got some additional cutting disks as well.

Hows everyone else holding up?
gohm
gohm • Aug 28, 2008
Been crazy with work so haven't spent much time on the Bot ๐Ÿ˜”
KINETIC_JOULES
KINETIC_JOULES • Aug 28, 2008
Wow, guys! I know I haven't been active lately! I've just got a lot of stuff going on right now. Please forgive me, as I am SO sorry. . .
๐Ÿ˜’....everyone seems to be busy..... :?:
haha ๐Ÿ˜› busy times, I suppose!

docel, what type of power supply do you recommend? We think of using Sealed Lead Acid for the motors. For the subsystems, we might either use SLA again, or try Lithium-Poly. We might need to boost up the voltage for the laptop system board.. they usually require 18V. Will need to verify with xhx though for his Acer system.
1. ....in the long run, a Mini-ITX or Pico ITX board may be a good choice, rather than a Laptop.

2. Sealed Lead acid batteries will add 2.5kgs to the weight budget. It will need some good motors to move that load.

3. The Laptop is of choice due to the "All Systems Aboard". Unfortunately , the least prefered component of the Laptop is the most power hungry!!
4. The dual battery system is THE way to go, if brownouts are to be eliminated.
xheavenlyx
xheavenlyx • Aug 31, 2008
@Docel:

1. I dont know how I am agreeing but it seems to be a good idea to use another board that's SPECIFICALLY for mobile/embedded applications with more needed ports e.g: USB's and serials and PCI slots. Ash what do you think? But before we go further with Mini-ITX/Mini-ATX, we will do a small (very small) research on different available types/boards. And then decide determined by certain factors.

2. I dont know about Lead Acid. They do provide acceptable power/energy but the weight problem. We might have to comprise on one of the 2 factors! Lets see.

3.
the least prefered component of the Laptop is the most power hungry!!
Which component is leastprefered and most power hungry?

4. Dual Battry is extremely importtant! Its one of the golden rule in robotics!! We never mix high power analog consumption (motors) with high power digital consumptopn (laptop/sensors).

===========

I said I will be presenting the sesors prsentation. Its still under construction ๐Ÿ˜” beacuse of my convocation (i recieved my college degree on 27th, shit I didnt tell anyone!! ๐Ÿ˜ I will make a new thread ๐Ÿ˜› )
The "least preffered and most Power-hungry" ::
Display, CD-DVD drive, HDD, BTh/wifi/PCMCIA, lOW RAM.......
.....in that order.

Display and CD-DVD are least preferred for a Laptop on-board a Robot. The stupid ROM drive spins all the time!!
Hey all! Good to see the discussions rolling.

Batteries:

Locomotive Module

Yep, SLA's are quite heavy, but a weight of 2- 2.5kg is acceptable for now. SLA are pretty standard for heavy robots ๐Ÿ˜€ I believe the locomotive module will be the heaviest one anyway, considering the multiple motors and chassis.. so relatively, the batteries are light.
- Its cheap
- High capacity
- Easy to recycle
- Easy to recharge (and can be recharged many times). Maybe can make use of solar cells?
- Reliable with tough and sturdy construction

For some numbers, we can get an 12V SLA with a capacity of 7000mAH for around 1.8 Kg. We probably need 12V for the good quality motors we'll use.

What we need to figure out is the total current draw of the motors.. which depends on the load (ie total mass of the robot and surface inclination).

System Module
For this one, I recommend using Lithium Polymer or NiMH. LiPo is very desirable for ALL purposes (including motor), but they are super expensive and quite hard to recharge. Both are lighter than SLA, but do not enjoy the tough construction.. so are quite fragile if not handled properly.

The system board module will need to be light because it'll be used in multiple situations (ie with other types of locomotive modules), so SLA's are ruled out.

Before we proceed, we need to know the total power budget of the system board. xhx, can you provide us with all the possible power specs of the laptop?

I think the most important battery factor would be capacity. We can use boost and buck regulators to give whatever voltage level we desire, but we still face the limited total current capacity issue.

Laptop weight issues
We are planning to rid of the LCD monitor anyway and use the VGA connector whenever we need to debug. Also, the HDD will be replaced by a flash disk via a IDE adaptor. We might still need the CD-ROM to boot the software though, unless we place the OS directly on the flash disk.

The WiFi will be the biggest power consumer. That one we cannot do much about for now. Since we only got 2 USB ports, we'll use the PCMIA port for the 802.11g module.
KINETIC_JOULES
KINETIC_JOULES • Sep 1, 2008
Wow. . . nice! I'll be contriuting more now, i just got a new scanner/printer! I can draw out a design, scan it, and put it on here for you guys! I've just got to go start on the design soon. I don't have to ho back to school 'till Thursday 'cuz of the hurricane, so I'm good!
raj87verma88
raj87verma88 • Sep 2, 2008
A lot has happened in the past few weeks and I have missed all the action. Will need to read a lot to catch up with you guys.
xheavenlyx
xheavenlyx • Sep 2, 2008
Batteries:

I guess SLA can be used for the motors, yeaaa, even I was worried about the weight, until I realized our bot will be pretty heavy compared to 2.5kg. Your normal fighter bots are 100+kg.

Li-Ion/NiMh/Li-Po: One of these, specially depends on 2 main factors, as you ahve already pointed out.


Ash: Before we proceed, we need to know the total power budget of the system board. xhx, can you provide us with all the possible power specs of the laptop?
Yes, thats very important. but you know, I am very tempted to look at dedicated motherboards specially meant for embedded applications as they are more "adept" to those kind of applications. what do you say? However, it may costtt ๐Ÿ˜€ ๐Ÿ˜€
Ashraf HZ
Ashraf HZ • Sep 4, 2008
Yep, but I guess our first prototype can still use your system board ๐Ÿ˜€

Do you still have the battery of the laptop? There should be a Voltage and Total Current capacity values written on it. How long does the battery last under heavy use (1 hour?). That'll be enough to determine the power consumption.

Also, the laptop charger has a current draw value written on it. It's rated higher than the laptop needs (because the extra amperage will be used for charging), so we can use that as the Max current draw ๐Ÿ˜€
xheavenlyx
xheavenlyx • Sep 5, 2008
Ok, thats there. For the first type we can recycle a laptop board. Thats good.

One problem is there, that the Laptop battery is no longer functioning. And I am not at all sure if I have it, but still, as you said the power/current rating is written on the back, or online.

Since this bot is modular, we have to make it as easy as possible to assemble and dissemble it.
Okay, here we go:
Battery Type: Ni-MH
Voltage: 9.60V
Capacity: 4000mAh
From: BTP-1731, BTP-1831, Acer Extensa 501 Laptop Battery

So we know now the system needs 9.6V.. or, the power board on the system board is design to work with those voltages anyway ๐Ÿ˜›

To break some rules, I'm going to follow some assumptions. For NiMH batteries, the maximum current draw should not exceed 70% of the total capacity. Thus, 0.7 x 4000 = 2800 mA.

therefore,
Max Current Draw: 2800 mA
Max Power: 26.88 W

Of course, a more accurate method would be to test the thing. But if we were to overestimate the power tolerances, hopefully we wont face any probs ๐Ÿ˜›
xheavenlyx
xheavenlyx • Sep 11, 2008
Hey thanks a lot for the information! And I think 2800mA means the Peak current draw, which maybe very less on standby's and non-intensive work. At the peak the maximum thats taken is 2.8A! That is at max function, the laptop will function for about (4000mAh/2800mA)=~ 1.4Hrs.

Which is alright for now, I guess.

And yea, the sensor document is still going on. To tell you the truth, its much more difficult than I though, each detail is important, as I am realizing on the way to completion. It will be an extensive (as much as possible) work, so be prepared to read it through and also make changes where you feel strongly.
KINETIC_JOULES
KINETIC_JOULES • Sep 11, 2008
Question. . . what do you guys have for me to do right now?
xheavenlyx
Hey thanks a lot for the information! And I think 2800mA means the Peak current draw, which maybe very less on standby's and non-intensive work. At the peak the maximum thats taken is 2.8A! That is at max function, the laptop will function for about (4000mAh/2800mA)=~ 1.4Hrs.

Which is alright for now, I guess.

And yea, the sensor document is still going on. To tell you the truth, its much more difficult than I though, each detail is important, as I am realizing on the way to completion. It will be an extensive (as much as possible) work, so be prepared to read it through and also make changes where you feel strongly.
No worries, I know the feeling of doing a detailed sensor documentation from my CANSAT project, haha. You don't need to make it really detailed. We can add more stuff at a later date ๐Ÿ˜€ Good luck with it!

Yes, 2.8A is the expected maximum theoretical peak of the system board. This is still an assumption though.. theres no real official figure at the moment, haha. We still need to take account for the Webcam connected to the USB and also the communications. For the communications, I propose we use a 802.11 device that can connect to the PCMIA port.. since it's not being utilized for anything at the moment.

Also, I think we should do a short proposal documentation. Mayur has requested it a while back for the purpose of finding sponsorship. I can try doing an outline by the end of this month maybe.

KINETIC_JOULES
Question. . . what do you guys have for me to do right now?
Can you design a logo for the CE Bot project? ๐Ÿ˜€ We can assume the final name is "Crazy Engineers Research and Recon Robot" or "CE:R[sup]3[/sup].

If you wish, feel free to continue with the Chassis designs. It's more likely we are going to use the original 6 wheel design. Can you do something like this drawing?

[โ€‹IMG]
[โ€‹IMG]
Kaustubh Katdare
Kaustubh Katdare • Sep 13, 2008
[Request] Time to close this thread and start CE BOT Part Three [/Request]
Just a few more things to tie up before closing ๐Ÿ˜€
KINETIC_JOULES
KINETIC_JOULES • Sep 13, 2008
Will do! I've got a new scanner, so. . . I'm happy!
KINETIC_JOULES
Will do! I've got a new scanner, so. . . I'm happy!
Good, can't wait to see your designs!
KINETIC_JOULES
KINETIC_JOULES • Sep 17, 2008
Hey, guys! There's something I have to tell you! I can't design for you guys anymore. I have my reasons. I'm sorry for any inconvenience and I want you all to know that I don't REALLY want to quit, but I have to. I'm so sorry guys! I love you all and keep up the good work! Hopefully, you can find another designer better than me!

Love,
Tyler Aka KJ
KINETIC_JOULES
Hey, guys! There's something I have to tell you! I can't design for you guys anymore. I have my reasons. I'm sorry for any inconvenience and I want you all to know that I don't REALLY want to quit, but I have to. I'm so sorry guys! I love you all and keep up the good work! Hopefully, you can find another designer better than me!

Love,
Tyler Aka KJ
What??? Thats very unfortunate to hear! ๐Ÿ˜” You have contributed a lot of great designs, and we were really looking forward for your upcoming ones!

Hopefully you'll change your mind someday and reconsider. CE Bot project wont be the same without your contributions and efforts!

Are you still going to be posting on the CE forums though?
KINETIC_JOULES
KINETIC_JOULES • Sep 19, 2008
Yeah, I will. School is just stressing me right now. I'll still try to contribute! Who knows, maybe I haven't completely given up after all!
gohm
gohm • Sep 21, 2008
No problem! Studies are what's important for you right now. You've been a help and we know you'll continue to help and contribute as much as you can.
KINETIC_JOULES
KINETIC_JOULES • Sep 21, 2008
Thank you all for understanding! I love y'all!
raj87verma88
raj87verma88 • Sep 22, 2008
@Ash: Will be mailing you some notes which I found online.
@Biggie: Yeah, Part 3 may be a good idea as this thread too is filling up rapidly.
@KJ: Thanks for all your help. Hope you will be able to rejoin as soon as possible.
Ah yes, studies are important indeed. I myself went on a haitus from CE for a while *grin* Good luck with it!

@patty
will look forward for that!
Okay, I concede ๐Ÿ˜› Time to lock this thread up! Thank you all for your great contributions ๐Ÿ˜€

Please continue discussions over at:

https://www.crazyengineers.com/forum/ce-labs/5315-ce-project-ce-bot-part-three.html

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