An Energy-saving Series Elastic Actuator with Variable Torque-speed Characteristics Using Reconfigurable Epicyclic-Driven Actuation

Series elastic actuators (SEAs) have been popularly studied as an alternative to rigid actuators due to their high compliance, reliable back-drivability, and necessary transparency. Owing to these advantages, SEAs are employed to achieve safe and efficient human-robot physical interaction, such as wearable robotics and prosthetics. However, because its inherent transmission ratio cannot be changed, the energy consumed by SEAs tends to be large to realize high torque output. Therefore, it is not easy to achieve force capability while maintaining a limited size. To overcome this deficiency, in this study, we developed a novel SEA with variable torque-speed characteristics (VTSEA) based on reconfigurable epicyclic-driven actuation to significantly save electrical energy and optimize the mechanical clutch of VTSEA to obtain a compact size and a large holding force. The experimental results show that the energy consumed by the proposed VTSEA is significantly reduced by over 40% compared with that of the conventional SEA.