Design and Control of a Cable-Driven Series Elastic Actuator for Exoskeleton

Abstract

In this paper, a cable-driven series elastic actuator (SEA) is proposed to improve the flexibility of the exoskeleton robot. This actuator combines SEA and Bowden cable to realize the compliant actuation of exoskeleton joints, which has the contraction performance similar to biological muscles. The torsion spring based on the flexure hinge is introduced into the design of SEA’s elastic element to reduce the mass and structural complexity of SEA. Then, the dynamic model of the cable-driven SEA is established and the PD controller is designed which is optimized by the linear quadratic regulator method. Finally, the performance of the actuator is evaluated. The results of sinusoidal tracking experiments show that the tracking performance is better with a frequency of 0.5 Hz and a torque of 1 Nm, and the root-mean-squared error (RMSE) is 0.0588 Nm, while the RMSE is 0.1960 Nm in the experiments with a frequency of 1 Hz and a torque of 1.6 Nm.