What's a good method for electrically measuring torque in a DC motor?

Question

Is there a method of measuring the torque output of a DC motor, using constants given in a motor's data sheet? I know the data sheet tells you how much torque the motor will put out at a given current input, but I'd like to be able to measure torque without an expensive torque transducer. Couldn't I have the motor in question drive another motor of known characteristics and then measure voltage/current of the known motor, then convert voltage/current to a torque?

Answer 1

I'm not really sure what you are asking. If you know the theoretical torque output for a given motor at a given current, then all you should need is a current meter. If you don't trust the theortical constants give in the motor data sheet, then using a second motor/generator won't really help, because you would be relying on the constants given in the other motor's data sheet to produce the torque meter you described.

Couldn't you just hook up the motor to a pulley, and have the pulley lift a weight of known mass, and see how much current is drawn by the motor using a current meter?

Answer 2

It depends on what you want to measure. Connecting the motor to another motor would not help unless that other motor were calibrated also. The only reliable way is to actually measure the twisting force on the load motor. This would usually be done by using load cells on the mounting feet for the load (or driving motor). Then you can determine torque at various power and speed settings.

Answer 3

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