A New Method to Measure the Output Torque for Micromotor

A noncontact measuring method has been proposed to measure the micronewton meter-order output microtorque of micromotors to overcome the problem of large measurement errors caused by temperature, vibration, friction, and the flow of air. Physical model of this method is built according to Newton's third law and the electromagnetic theory. To realize this method, an apparatus named noncontact microtorque measuring equipment is designed to measure the output torque of micronewton meter-order micromotors. This device is mainly composed of electromagnetic windings, control circuit, an electronic balance, and a photoelectric sensor. Working principle of this device is introduced and the measured precisions of rotating speed and microtorque of the device are also analyzed in detail. Finally, a microelectromechanical system fabricated planar dc micromotor is tested by this device. The analyzed precision of the microtorque is 0.01 μN · m, which is precise enough for the measurement. The tested result indicates this method is feasible to measure the micronewton meter-order output microtorque of the micromotor.