A Robust Adaptive Admittance Control Scheme for Robotic Knee Prosthesis Using Human-Inspired Virtual Constraints

• Main Authors: Yongshan Huang, An Honglei, Qing Wei, Ma Hongxu
• Format: Article
• Language: English
• Published: IEEE 2020-01-01
• Series: IEEE Access
• Subjects: Knee prosthesis; virtual constraints; admittance control; robust adaptive control; composite reaching law
• Online Access: https://ieeexplore.ieee.org/document/9187769/

A robust adaptive admittance control scheme using human-inspired virtual constraints was presented for a robotic knee prosthesis. The controller is able to deal with the wearer's motion intention as well as the partial unknown parameter values of the prosthesis dynamics. The desired trajectory of the prosthetic knee joint is parameterized by the amputee-driven thigh phase variable and implemented by human-inspired virtual constraints rather than the preprogrammed time-dependent trajectory or human data replaying. A reference admittance model was set up to make the prosthesis be more compliant in the presence of ground reaction forces impact. A composite reaching law is proposed to cope with the chattering phenomenon and the finite-time convergence problem. The controller is designed by the back-stepping method based on Lyapunov. The tracking performance and the stability of the closed-loop system are proven via Lyapunov stability analysis. The feasibility and effectiveness of the proposed control scheme are proved in simulation results.