Linear and Angular Position Sensing for Two- Degrees-of-Freedom Motor

A linear and rotational two-degrees-of-freedom switched reluctance motor (2DOF-SRM) has been developed to independently control linear and rotational actuation on one actuator. The 2DOF-SRM drive system requires information on the linear and angular positions of the rotor for its control. The approximate angular position of the prototype 2DOF-SRM rotor was detected by the built-in photo-switches that utilize the salient pole of the rotor as the sensor target. The linear position of the rotor was detected by an external linear position sensor mechanically connected to the output shaft. To simplify this sensing system and improve sensing resolution, this paper presents a noncontact optical sensing method to simultaneously detect linear and angular positions of an actuating 2DOF-SRM rotor. The sensing principle for detecting the combined linear and rotational motion of the 2DOF-SRM and the performance of the linear and angular position sensing system are reported.