4x4 software differential

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Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]


Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 11/5/2000 7:26 PM MST


In Reply to: Re: 4x4 software differential posted by James on 11/5/2000 4:04 PM MST:



I think you need to really think out your whole system.

I would recommend that you have the steering angle set to the X axis of the joystick via a feedback loop.
Then you need to coordinate the throttle settings for your left and right wheel.

In my opinion, it is often best to have a 'base throttle' and a 'throttle off-set'

Base throttle could be set via the Y axis.

Throttle off-set is an add to one side and a subtract from the other.

For my money, estimates work just fine rather than going with the perfect mathmatical corrections.

I try to match things at the end points, specifically, going straight ahead and turning as sharply as you will in competition (45 deg?).

Anyway, contrary to Nick's opinion that the software should not be too much of the equations, I believe that the software in this case can be VERY tricky to get right. The corrections change signs based on the angle of steering & direction of base throttle. You can easily drive yourself nuts making sure you have it all worked out.

I wish you luck.

Joe J.