Impedance Modulation Control of a Lower-Limb Exoskeleton to Assist Sit-to-Stand Movements

As an important movement of the daily living activities, sit-to-stand (STS) is usually a difficult task facing elderly and dependent people. In this article, novel impedance modulation strategy lower-limb exoskeleton proposed to provide appropriate power balance assistance during STS movements while preserving wearer’s control priority. The ensures adaptation mechanical human–exoskeleton system toward desired one requiring less effect reinforcing ability movements. A human joint torque observer designed estimate torques developed by wearer using position kinematics instead electromyography or force sensors; time-varying model according motion ability. virtual environmental for reinforcement control. Stability robustness method are theoretically analyzed. Simulations implemented illustrate characteristics performance approach. Experiments with four healthy subjects carried out evaluate effectiveness show satisfactory results in terms assist reinforcement.