CE Project: CE Bot [PART TWO]

[ash]

Originally Posted by 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:

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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:

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I hope the "text art" is understandable. A little lazy to open a graphics program

Originally Posted by 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]

Originally Posted by 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]

Originally Posted by 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]

Originally Posted by 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]

Originally Posted by 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: http://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]

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]

Originally Posted by 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?

[ash]

Yep, indeed

Other than seeing what the CE Bot may look like, we also are interested on how the parts are connected to each other.

[xheavenlyx]

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::: http://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]

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.