CE Project: CE Bot [PART TWO]

[ash]

Great work, xhx! We were sorely in need of case studies

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 Of course, this assumes that we want the front and rear wheels to rotate at the same speed.

[KINETIC_JOULES]

Welcome back! Ok, now get back to work

*Salutes* Yes sir!

[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.

[KINETIC_JOULES]

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]

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]

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.

[ash]

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

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: CE Project: CE Bot ), 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 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]

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]

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/crazyengi...t/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 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]

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/crazyengi...t/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 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.