High-Power and Precise Actuation System with Direct Drive and Variable Structured Elasticity

Variable-structured elastic actuator is researched as an actuator which enables high speed motion. In the conventional research, the actuation method has two periods. The first is charging period: elastic potential energy is charged by the geared motor with clutching. The second is releasing period: the clutch is disengaged and high-speed motion is attained in load side. However, it is difficult to attain the high-speed motion precisely because it is impossible to control the motion in the releasing period. This paper proposes an integrated actuation system which is composed of the elastic actuator and a direct-drive motor. The direct-drive motor is attached to the load side of the elastic actuator. Actuation method of the proposed actuator system also has two periods: charging period and releasing period. In the charging period, the actuator system stores potential energy like the conventional method. In the releasing period, the direct-drive motor controls the motion precisely while the clutch is disengaged. Performance of the proposed actuator system is compared with the conventional system through experiments.