Braking with victors

[joelg236]

2 pretty basic questions for you guys:
1.How have you managed braking so far with victors? We only have 4 jags (set up with driving) and using victors for an arm-type apparatus. We'd like to set it up so that we can stop the arm in different positions (using encoders to measure the distance) but braking with victors seems to be ineffective. Nothing happens in term of stopping the motors. The just stop outputting, and our arm falls down. Id really like some way to hold it still in one position like brakes in the jags. Is there a known way to do this>

2.For some reason initializing a victor and running victor.set(speed) does nothing for us, but initializing them as a RobotDrive works. This seems like there is something different about RobotDrive, because we use the same inputs on both. Whats the best way to use victors in the wpilibj libraries? Or do you make a class for it?

[Ether]

Id really like some way to hold it still in one position like brakes in the jags.

The brakes in the Jags provide dynamic braking only, not static braking. Unless you have a high gear ratio gearbox that doesn't backdrive easily, the Jags won't hold it either.

What motor are you using, and what total gear ratio (gearbox plus any sprocket ratios), and what is the magnitude of the torque required to hold the arm?

[joelg236]

Gearbox ration is 256 - 1
I don't really know what the motors are, but they are really powerful.
Dont know the torque either.

[Ether]

Gearbox ration is 256 - 1
I don't really know what the motors are, but they are really powerful.
Dont know the torque either.

If you are using really powerful motors with a 256:1 gearbox to lift an arm, you better know the torque. There's a torque limit on those 256:1 gearboxes, and it's a lot lower than you might think.

[jesusrambo]

If you have an encoder on your motors you can use a PID controller to hold them in place.

[joelg236]

Yep. Our team learnt that today. Broke a gearbox. I know, derp-di-derp. Were a rookie team. :P