Apparatus for measuring torque, inertia moment, output and backlash

Abstract

Characteristic parameters of a torque of a stepping motor and its associated driving current or voltage are measured in advance to providetorque vs. characteristic information data representative of the torque vs. driving current/voltage characterisitcs. Then, the above characteristic parameters are measured again when a real load is applied to a stepping motor as installed with associated mechanical coupling components. An actual load torque is determined by referencing the subsequently measured characteristic parameters to the previously obtained torque vs. characteristic information data. A load inertia moment can be determined by subtracting the motor's rotor inertia moment from a determined inertia moment of the entire system. Efficiency of the motor can be determined by multiplying the output of the measured load torque by the nuber of revolutions per second thereof and dividing this by the power supplied to the motor or driving circuit. Backlash can be determined from the play in the changes of associated current waveforms corresponding to particular intervals, i.e., an interval from when the direction of rotationof the motor is changed to when the load torque increases again.