Walking Assistance Through Impedance Control of a Lower-Limb Exoskeleton

This paper presents a control approach of a lower limb exoskeleton by modulating the original impedance of the wearer' swinging leg to reduce the muscular efforts. The proposed method ensures compensation of the damping and gravity effects of the wearer's leg to desired levels offering though the possibility to adapt the lower limb wearer's impedance as a function of the gait phase evolution. The performance of the proposed approach is evaluated by carrying out experiments with two healthy subjects. The EMG activities of the extensor muscles spanning the knee joint are used as assesment criteria. The results show that the muscular activities required to perform the same flexion/extension movements are effectively reduced by providing lower desired joint damping and stiffness with exoskeleton's assistance.