Design of an inchworm actuator based on a ferromagnetic shape memory alloy composite

A new inchworm actuator has been designed and fabricated based on a ferromagnetic shape memory alloy (FSMA) composite and the hybrid mechanism. The FSMA composite consists of a ferromagnetic material (soft magnet) and a superelastic grade shape memory alloy. The hybrid mechanism is found to provide relatively large force and stroke with fast response on the FSMA composite because it can be driven by a compact electromagnetic driver with high applied magnetic field gradient, providing a large stress capability and reasonably large strain. The inchworm actuator exhibits moderate output force and very large displacement, achieved by accumulating many small strokes based on the inchworm mechanism. The prototype inchworm actuator successfully produces 30 N force and 65 mm s−1 stroke velocity. (paper)