Abstract: A rotation control apparatus for a differential actuator includes two induction motors and a differential mechanism for producing a constant torque on its output shaft based on the differential speed of the induction motors. The appartus includes two inverters each located between one of the induction motors and a common power source for the induction motors and having individual voltage/frequency output characteristics. The inverters set separately the voltage/frequency output characteristics of power supplied to the induction motors so as to control the speed of the induction motors separately, thereby controlling the output torque on the output shaft of the differential actuator. And the output shaft of the differential actuator is controlled to constant speeds regardless of the load torque on the shaft based on the difference of setting frequencies on both inverters.

Abstract: A differential actuator including a pair of unit actuators enclosed in a housing is provided. Rotational shafts of the unit actuators support bevel gears in opposed relation to each other. These bevel gears constitute a differential mechanism conjointly with two differential gears which are interconnected rotatably. Rotation of the differential gears around the axis of the bevel gears is taken out to the exterior as an output of the actuator.