2 Wheel Drift
I have a 2 wheeled robot - 2 GM10's with little thin wheels. I've hooked them up to an arduino with an L293. I have it going forwards, backwards & turning well enough. The problem is when going forward, it seems to drift to the right slightly. Any suggestions as to what the problem might be? Do I need wider wheels? A proper castor? (ATM, the front of the chassis rests on the ground).
Basically, what I'm asking is, with 2 small motors and thin wheels, can I expect a bot to go in a perfectly straight line?
Thanks!
@ Wed, 2008-11-19 09:05
Toe Out
Oooh I read about this last night. How sad is that?
The directional stability of a wheeled robot will be greatly improved if the wheels have slight "toe out". That means that the wheels are not perfectly vertical, they angle slightly outwards towards the bottom. Without drawing a picture, seen from the front or back your robot would look a little bit like an "A". A heay robot with cheap or no axle bearings will probably achieve this naturally.
Mike
@ Wed, 2008-11-19 10:39
I do not believe the
I do not believe the "A-shape" or any other ways of distorting the wheels will do anything but possibly slow down the speed, and so both limit the sliding.. but also limit the forward motion.
Near-prefect angled wheels will give you a near perfect straight line. But as stated above; why would you want that?
In my world the programming, sensors, brains should ensure that the robot reaches it's goal, even if the wheels are completely out of sync & order. This is why it is given brains; to decide where to go, and compensate for whatever distortion the surroundings may cause.This is why it is autonomous, and not just dumb like a cheap copying-machine or a train etc.
@ Thu, 2008-10-16 13:01
I had this same problem with
@ Thu, 2008-10-16 01:36
Thanks
Thanks for all the comments. I'm thinking that the structure is a large factor in all of this. Initially, there was little weight over the wheels, so they didn't really move the bot along by much. Now I've moved the battery ot provide weight, but it's been done in a haphazard way. I haven't paid any attention whasoever to distribution of weight.
My plan is to build a simple plastic chassisto place it all on, and figure out a nice place for the battery. Add a hemisphere to the chassis to steady it and see how it goes.
I'll let you guys know.
Thanks
g
@ Wed, 2008-10-15 21:43
Just do what I do...
@ Wed, 2008-10-15 21:46
self stabilizing technology
@ Wed, 2008-10-15 21:49
Dog Hair
@ Wed, 2008-10-15 21:58
Chris has more homework
@ Wed, 2008-10-15 17:00
Does anything go straight?
@ Fri, 2008-10-17 22:48
"Sometimes we like our world
"Sometimes we like our world to be orderly. And a robot traveling a strsight line can be good, but is it really necessary? I believe that if you simply keep track of where you are going, the straightness of getting there doesn't really matter. And the process of keeping track (odometry) can actually give a tool to "straighten" with, if need be."
Yes, yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes , yes!!!
IMHO it is only fun if you can make your robot half way limb on one side / motor, and it just compensates.. because it just strives to go where it is aiming to go.
That is because I am an 100% arty. This one of the most secure ways of telling if you are an arty or techie. Techies are looking for robots to go in order so they can tell where it is, measured etc. Arties do not care, they strive on making therobot "understand" what the goal is, and then just get there by humbing, bumping, driving or jumping :D