Evaluation of the dynamic properties of a Voice Coil Motor (VCM)

The electrical and mechanical characteristics of a voice coil linear motor under moving conditions are evaluated using a method based on the levitation mass method (LMM). The force generated by the actuator is measured as the inertial force of the mass, which is levitated with sufficiently small friction using a pneumatic linear bearing. The moving mass of the bearing is connected to the moving part of the actuator. During the measurement, only the Doppler shift frequency of the laser beam reflected by the mass is accurately measured using an optical interferometer. Then, the velocity, the position, the acceleration and the inertial force of the mass are calculated from the frequency. Simultaneously, the current and the voltage supplied to the actuator are measured.