One Side Drives Faster than the Other.

[Justin M.]

Originally Posted by kaszeta

Typically we use a single joystick drive (y-axis commands speed, and x-axis commands the turning rate), but the difference between the two sticks should work as well.

I've posted sample PID code for the gyro in some other threads, just look at some of my recent posts. Nothing terribly difficult to implement, although it helps to have an understanding of how feedback loops work.

Today we tried doing uploading a single-stick control, just so I could try it out (I was curious as to how it would drive). We had the same exact problem, one side was going faster than the other. This is why we ruled out one-stick driving, it's very hard to get the joystick perfectly in the y-axis to have even power, however, this probably can be fixed with better programming. If the joystick travels slightly diagonal, then a certain amount of power is applied more to the left motor, less to the right, and vice versa.

Once we switched back to our original tank drive (two joysticks), the robot drives like a dream. I prefer driving this way as well - try using two-stick control and see how your robot handles.

Otherwise it's mechanical. Test the gearboxes and poke around to see if theres any issues. Make sure the wheels are aligned perfectly with the chain, and the drive sprockets are properly mounted to the output shaft of the gearbox. Also if your chains are really tight, try slacking them up a bit, so they can be a bit more flexible.