We are using Victor SPX controllers on our elevator and looking to stop them at varying levels in relation to the bays on the rocket. We were planning to use an external brake but then noticed that the Victor SPX might have a brake mode. Does anyone know more about this? Would it work the way we think at stopping a heavy elevator from falling down? Do we need to use CAN instead of PWM? The software guide is a mix of Talon and Victor so we are not sure how this works on just the Victor side. Thanks for any help for this rookie team!
Brake mode may or may not work. It depends on the weight of your mechanism, the type of motor you’re using, and the gear ratio. I believe it works by connecting the two motor leads together, which causes the back EMF of the motor to resist rotation.
No, it will slow it from falling down, but not stop it, unless your lift is very close to weight neutral, in brake mode it essentially just crosses the motor leads, generating a high level of resistance, so the motor will slow down faster if power was previously applied, or give a bit more resistance against backdriving, but it does not actively keep the motor in a certain position, which is what you are trying to do, this can be accomplished with encoders on a PID loop, but to reduce load on the motor I would recommend a brake as you are suggesting, as a PID loop will burn out the motor unless you have an extremely high gear reduction so you can stall at a very low voltage, or your load is so low, that once again it can be stalled with little power applied.
It is a CIM motor with 36:1 gearbox attached to Victor SPX. We are using the lift kit from REV with three stages. Not sure how heavy it will be atop.