pulsing motors

[tilky]

i wrote a program in labview, starting out simple, with a tank drive in 2 joysticks and arcade in a 3rd. The code worked fine, however, with troubleshooting tehniques, we narrowed it down to the program. When we loaded the program into the robot, the motor made "grinding" noises, but only when we ran it off of the code (when we connected it directly to the battery it didn't do it). What it seems like is happening is it runs the motor, and turns the motor off hundreds of times a second. Has anyone ever heard of this problem happening and how to make it work?

[Mark McLeod]

You might be ordering the motors to do different things at once.
For instance, command it to go forward as well as be neutral at the same time. Depending on the code sometimes one command might win out, while at other times the opposite.

[plnyyanks]

It sounds like that you're using two joysticks to simultaneously control the robot (2 for tank, 1 for arcade). Since you - the human - are only interacting with one set of joysticks at one given point in time, the other joystick will read 0 when you're not using it. Therefore, every iteration through your code, two values will be set to the motor: one value (which is the one you want) from the joystick that you're actively using to control the robot, and another value from the joystick you're not using (which will give a 0). I can easily see why this setup would cause the symptoms you're describing.

To fix this, I wouldn't have your robot controlled in this manor. Maybe have a joystick button you have to hold down in order to go into a certain drive mode, or a switchbox switch. But don't have both types of control happening in parallel - then two values will be get set to the motor each iteration - and that's bad.

[tilky]

i am currently working on that method, i can't believe i was that stupid not to realize that!