Design and Validation of a Lightweight Hip Exoskeleton Driven by Series Elastic Actuator With Two-Motor Variable Speed Transmission

Abstract

To overcome the different requirements of torquevelocity characteristics for walking, running, stand-to-sit, sit-tostand, and climbing stairs, we propose a novel concept for actuator design, namely, a series elastic actuator with two-motor variable speed transmission. The two-motor variable speed transmission can be adjusted in real-time to realize variable torque-velocity characteristics. A novel lightweight wearable hip exoskeleton driven by a series elastic actuator with two-motor variable speed transmission, named SoochowExo, has been developed in this paper for use in the elderly population. The weight of the whole hip exoskeleton is 2.85 kg (excluding batteries), including two actuators and the frame. The proposed hip exoskeleton can match the weight of the state-of-the-art hip exoskeleton while offering suitable torque and velocity for sitting-to-standing, walking, running on level ground, and climbing stairs. The benchtop tests and the preliminary human subject tests further confirm the design.

Series-elastic actuator with two degree-of-freedom PID control improves torque control in a powered knee exoskeleton

“…A multitude of SEA designs for powered lower-limb exoskeletons has been proposed. A common implementation of SEAs for powered exoskeletons consists of using a torsional spring in combination with planetary or harmonic-drive gearboxes (Chen et al, 2017 ; Kim and Bae, 2017 ; Aguirre-Ollinger and Yu, 2021 ; Zhang et al, 2022 ). These solutions tend to be quite compact but have some drawbacks.…”