Locking a Motor

[anthonygraff24]

If I set a motor to 0 power, will that lock the motor? We are picking up the recycling bin with a winch and pulley mechanism, so if the motor driving the winch is allowed to free-spool we are worried that when the weight of the recycling bin is placed on the free-spooling winch the bin will move down. I'm not sure if simply setting the motor to 0 power will lock the motor, or if there is another command to lock a motor.

[kgzak]

No, setting the output of a motor to 0 will not lock the motor in place, it will just not output anything to the motor. The motor controllers have a brake/coast jumper/function that can cause the motor to brake which may or may not be enough to keep the motor from moving. You could also drive the motor at a very slow speed that counteracts the force of the totes. otherwise a simple mechanical brake can be used to hold the motor in place.

[ozrien]

kgzak is correct. Talon SR, Jaguar, and Victor 888s have a brake/coast jumper.
Victor SP has a button to select brake vs coast in neutral mode.
Talon SRX has a button to select brake vs coast, and can be software selected over CAN bus.

See Talon SR User's Manual for more info for original Talon and Talon SR.
See Talon SRX User's Guide for more info.
See Victor SP's Quick Start for more info.

"Brake during neutral" simply means that when 0 the motor leads are connected together. I wouldn't say it's "locked", but the generated back electromotive force will resist the rotation of the motor.

[Ether]

Originally Posted by ozrien

I wouldn't say it's "locked", but the generated back electromotive force will resist the rotation of the motor.

The braking torque is proportional to speed.

[DonRotolo]

Originally Posted by Ether

The braking torque is proportional to speed.

Yes, because the 'brake' is simply a short across the motor which is acting as a generator, causing the generator to have a load which slows it down. But only when it is moving, and when moving slow the effect is minimal.

Anthony, you need to find a different solution to lock the motor in place, in general adding a little power to hold the motor still is not good for the motor (it gets hot, sometimes too hot).

[Poseidon5817]

You could do it mechanically or set it to hold its position with a PID loop.

[DonRotolo]

Originally Posted by DonRotolo

to hold the motor still is not good for the motor (it gets hot, sometimes too hot).

Originally Posted by Poseidon1671

You could do it mechanically or set it to hold its position with a PID loop.

Mechanically is a good idea. PID loop maybe not so much.

[Michael Hill]

Originally Posted by DonRotolo

Mechanically is a good idea. PID loop maybe not so much.

I like mechanical. Take a look at the CAD of 118's robot from a couple years ago (don't remember exactly which year). They had a mechanical gear brake in their drive system.