On a high-backdrivable direct-drive actuator for musculoskeletal bipedal robots

This paper reports on newly developed small-size prototypes of spiral motors for a musculoskeletal robot application. The prototype has smooth helical surface so that the mover can touch down the stator. The stator core is made from SMC (Soft Magnetic Composite) in order to reduce iron loss. Helical-shape permanent magnets are mounted on the surface of the mover. The motor realizes compact direct-drive motion systems. A concept and design sketch of a musculoskeletal robot in which the spiral motors are installed as artificial muscle is shown. Also modeling and control of the spiral motor are reported.