View Full Version : Quatro 4 wheel drive

04-14-2004, 07:23 PM
I have thought about building a feedback system for a robot that controls slip on the wheels, and keeps the robot going where u want it to go.

I have figure that the best way to do this would to be having four seperate gearboxes driving four seperate wheels. Then a shaft encoder would provide feedback for the program to make sure all four wheels are moving at the same speed. The friction a wheel delivers when it is slipping along the ground is much less than if it were not slipping along the ground. SO if one of the wheels hits the ramp like in this years game, that wheel would emidiatly slow-down. On the regular system the other wheels would start slipping and lose the traction ability, and not be able to push the robot up the ramp. In my system the other wheels would slow down aswell until there are spinning the same speed as the other one and gain maximum tractiuon to push the robot up the ramp. ALso you could make a super high torque gear box and acctually be able to use all the torque avaliable, instead of just spinning you wheels.

It works the same against an opponent robot. Say you hit into it pushing it backwards. But then your wheels start to slip when u push it up against a wall. WIth the regular system your opponent robot now has a chance to push you back and get away. BUt with my system the wheels would emidiatly slow down to gain maximum traction and pin your opponent against the wall

Another advantage is that when you point the joystick forward the robot will go forward instead of turning slightly.

THere are a few problems with it. first I'm not much of a programmer so I'm not sure if it woyuld be possible to program all four wheels to spin at the same rate accuratly enough. ALso what if all four wheels start slipping at the same time, then the program will keep hem slipping.

I'm just wondering if anyone has any ideas they would like to add to the system, and any program code they would like to share with me to solve this problem. :cool:

04-14-2004, 08:45 PM
What do you mean, ALL the wheels start slipping?! How is that even possible? Better watch out man, those sudden puddles is the playing arena can really make or break a traction system.
</wiseguy> ;)

All kidding aside, what you describe is very doable. Methods for counting wheel rotations are extremely varied in FIRST, and this thread (http://www.chiefdelphi.com/forums/showthread.php?t=26726&highlight=wheel+rotations) does a good job of summing up your various options. As far as programming goes, read up on interrupts. Just search, I believe there are a few white papers on them, and if not, read the documentation. Hope that works out for you.