Load Torque Control of an Electromagnetic Motor with a Reduction Gear, a Spring, and Motor/Load-Side Encoders

Actuators that have characteristics such as a light weight, high torque-to-weight ratio, and good torque control performance are desirable for application in finger robots and power-assist suits. Although electromagnetic motors excel in torque control performance, they have low torque-to-weight ratios. Adding reduction gears gives them high torque-to-weight ratios, but backlash and friction degrade torque control performance. This paper therefore proposes a load torque control system using an electromagnetic motor with a reduction gear, a spring, and motor/load-side encoders. The effectiveness of the proposed control system is verified via simulation and experiment.