An optimization approach to design control strategies for soft wearable passive exoskeletons

Abstract

Soft assistive devices constitute a promising alternative to help people with mobility impairments. Nevertheless, some issues as the control of these systems preclude from their generalized usage in common daily activities. The objective of this paper is to obtain the activation profile for controlling a clutched spring to store and release energy in a way that helps the subject to achieve a specific movement target. To do this, a parameter and partially constrained optimization method has been implemented. The results obtained showed a clutch activation profile which is synchronized with a reduction of the hip flexion torque exerted by the subject. Additionally, significant computational times savings have been obtained due to important reductions of the size of the optimization problem introduced by a partitioning of the state and control vectors.