Articulated chassis robot, why not?

[tomassan]

Hi!!

My endavours into robotics is currently only on a theoretical level. I will in the near future hopefully start to build my very own design for an all-terrain wheeled or tracked robot.

I'm thinking about a four wheeled/four motored thingy with articulated chassis. My first eureka was to measure the angular difference between the front and back chassis halfes and by that discover the steering drift. But then I realized that I would probably not be able to have an active steering for the articulation. But still, the angular measurement idea is perhaps not so stupid if I could find the correct sensor to make it work.

I've also been thinking about wheels or tracks. What are the opinioin against tracks? WHat are the opinion against wheels?

Any ideas from you more experienced people?

Purpose and requirements of my robot:

- Speed doesn't matter, It may be slow I don't mind
- terrain capabilites, I would like it to be able to roam the most difficult terrain (read newly plowed ground...)
- To be a platform for perhaps a video camera to track my cats just to see what they are up to
- Wake me up in the morning with some freshly brewed coffey (just kidding)
- As cheap as possible
- Small but not to small to not be able to roam the grounds

I'm looking forward to some good input!

Regards,
Tomas Sandkvist
Sweden

[paulstreats]

be careful if you make it articulated in the middle, it can cause your robot to tip over easily. If the front and back of the bot are both aimed to the right, the point of pivot(in the middle) will be pointed over to the left side with nothing to support underneath

[tomassan]

be careful if you make it articulated in the middle, it can cause your robot to tip over easily. If the front and back of the bot are both aimed to the right, the point of pivot(in the middle) will be pointed over to the left side with nothing to support underneath

Yes that is correct. I'm thinking about some kind of mechanism like on a dumper, there has to be some end stop function the restricts the articulation. Another idea I'm tampering with is to use a servo to operate the articulation, that would even more emulate the dumper's hydraulic steering. But perhaps that would be overkill since I so easilly can control the motors.

[jgreenewv]

This is probably overkill for what you are considering, but it shows a functional articulated robot platform.

http://www.teamdelta.com/agr/agr-main.htm

Just take the basic layout, remove the armor and weapon, scale it to your desired size, and you should have something usable.

[airman00]

you mean like the packbot?


or you could make a spider robot platform

[SmAsH]

lol those are kewl does anyone know the real size for the packbot?

[airman00]

7" H x 20.2" W x 34.6" D

first hit on Google 

[SmAsH]

hmm...yea kewl thx

[Admin]

tomassan, I've seen a few robots as you describe. although I can't remember where off-hand, I'm sure if you google for awhile you will find some.

the main issue with them is if you want to turn with a lot of obstacles in the way. it gets really complicated going in reverse, etc.

oh and Im pro-wheels and anti-tracks . . . the reasons can be found on several posts in this forum.