A New Delayless Adaptive Oscillator for Gait Assistance

Tao Xue, Ziwei Wang, Tao Zhang, Ou Bai, Meng Zhang, Bin Han

Abstract: To obtain synchronized gait assistance, this paper presents a new delayless adaptive dual-oscillator (ADO) scheme to address the inherent delay issue. In the ADO structure, a new oscillator is coupled with the primitive one but the phase is adaptively feed-forward compensated. It’s remarkable that the compensated phase is determined by the proposed extended phase lag observer, in which both the phase lag and phase leading can be properly estimated and eliminated in the steady and non-steady gait. Moreover, a unified exoskeleton control scheme based on ADO is further proposed to improve the gait segmentation, velocity/acceleration estimation, intention estimation, and assistance generation performances, which further enhances the assistance synergy and reduces the safety risks. Experimental results demonstrate better alignment assistance and consequently reduced muscle efforts with ADO-based assistance control.