Transmission Torque Characteristics of Strain Wave Gear with 16-Poles Magnet

Lower limb exoskeletons with actuators aids disabled individuals in walking. We developed a light magnetic strain wave gear for lower limb exoskeletons, which uses magnets instead of a conventional mechanical cam. In this paper, we discussed the relationship between magnetic force vector and transmission torque, and we proposed a magnetic strain wave gear with 40 mm height 16-poles magnet. From the discussion, we clarified that an asymmetric radial directional force vector was an important factor for increasing maximum torque. The transmission torque of the proposed magnetic gear was analyzed through multi flexible body dynamics with a magnetic force database. The analyzed maximum torque was 15.6 Nm, which was three times as large as that of the previous magnetic strain wave gear. Then, the transmission torque of the proposed gear was measured using a torque sensor and brake, and the measured maximum torque was 8 Nm, which was 1.6 times as large as that of the previous gear.