Magnetic cogging parallel-elastic actuator

A system comprising:

• a first structural member;
• a second structural member coupled to the first structural member at a joint;
• and
• an actuator associated with the joint and operable move the first structural member relative to the second structural member about the joint, the actuator comprising:
• a motor comprising a first output shaft;
• and
• a cogging-torque element comprising:
• a stator that is stationary relative to the motor;
• a rotor that is rotatable relative to the stator and comprises a second output shaft;
• a plurality of stator magnet elements disposed radially about the stator;
• and
• a plurality of rotor magnet elements radially positioned about the rotor;
• wherein the second output shaft of the rotor of the cogging-torque element is connected in parallel with the first output shaft of the motor such that an output torque of the actuator is a sum of a torque of the cogging-torque element and a torque of the motor,
• wherein the first output shaft and the second output shaft rotate in the same direction, and wherein the first output shaft of the motor is parallel but not co-axial with the second output shaft of the cogging-torque element and each of the first and second output shafts are connected such that an output torque of the actuator is a sum of a torque of the cogging-torque element and a torque of the motor.