Hello,
I have a strange question. We have a motor that is connected to an elastic material that causes it to spin when in coast. I was wondering if it is possible to cause the motor to resist the material, but not so much that it doesn’t spin at all. So it should basically just slow down the spin.
Thanks a lot.
This sounds a lot like an arm needing gravity compensation. Would that scheme work changing sine/cosine to possibly a more linear spring equation?
Motor torque (rotational force) is proportional to current. Current is a function of motor speed, applied voltage, and some other constants.
By applying a voltage that varies based on speed, you can achieve a constant current through the motor windings. Picking the current such that it slightly opposes motion will create the effect you described.
Note most brushless motors support a constant current mode, which might also help. I have not used it much though, so it’s harder for me to recommend it.
What’s the application? Oriental Motor makes “torque motors” that are made for precisely this. You can also do digital torque control with a servo.
Controlling a motor in constant current mode will apply a constant torque. Note that you should carefully set speed limits to ensure that it stops if you remove the load.