Simulation and experiments of a hybrid actuated exoskeleton for assistance and rehabilitation

D. Chakarova, I. Veneva, P. Venev

Abstract: This article examines an exoskeleton of upper arm for assistance and rehabilitation. A solution has been proposed for the design and actuation of the exoskeleton, which ensures transparency and natural safety, as well as sufficient force and productivity. It uses hybrid actuation with electric and pneumatic actuators acting in parallel. A control algorithm is created, in which the pneumatic drive takes care of the initial reaction of the force, and the electric drive complements the pneumatic drive. An approach is used for dynamic assessment of the forces of interaction through imposed movements. The influences of the inertial, frictional, gravitational and elastic forces obtained from exoskeleton impedance are taken into account. A harmonic motion with increasing frequency in the second joint is simulated. In passive mode, the resistive torque of the device's impedance is considered as the force of interaction that is applied to the patient's arm. In active mode, the resistive torque is used to issue power commands to the electric drive to perform feed forward compensations. Transparency is assessed in different cases, depending on the active or passive management mode. Finally, conclusions and future work are given.

Series on Biomechanics, Vol.35 No.2 (2021), 21- 29

Keywords: Exoskeleton; interaction forces; rehabilitation

Date published: 2021-07-02