[archiver]

Posted by Ken Leung at 03/20/2001 3:10 PM EST


Student on team #192, Gunn Robotics Team, from Henry M. Gunn Senior High School.


In Reply to: Traction is Key!!!!
Posted by Elgin C on 03/20/2001 1:09 PM EST:



Good call about the traction...

Usually when people are thinking about a drive train, they usually only think about how much gear ratio the motors have, or how much speed/torque do the motors transfer onto the wheels.

However, that's only part of the problem. The over all goal of a drive train is to transfer one form of energy into another, and one form of an motion to another. Although motors take care of turning electrical energy into mechanical energy, you still have to think about how to transfer that rotational mechanical energy into linear motion.

The most common way of solving that problem is using wheels or thread. But you have to understand that those things work because of a major thing: Friction.

And from that standpoint, you have to start worry about how to get maximum friction allowed on the wheels/threads in order to get most from the rotational energy. Then you have analyze how the wheels/threads react under different kind of stress: the weight of the robot pushing onto the wheels, the carpet pushing against the wheels with the same amount of force the wheels are pushing against the carpet, side friction when spinning in circle... etc.

Finally you have to look and see if the material on the wheels are capable of taking so many stress, then think about the trade off between the life-time of the wheels, the energy you are losing, the cost of manufacturing, and the need for the competition...

After all these work, you should be able to conclude that normal wheelchair wheels are just not going to cut it, that is without any improvements anyway... But of course most people just need to try them out and immediately see the lack of traction.

Ha. Who need all the analysis when you can just test the stuff out?