Classification of Human Balance Recovery Strategies Through Kinematic Motor Synergy Analysis

A key problem in human balance recovery lies in understanding the mechanism of balance behavior with redundant bio-mechanical motors. Motor synergy has been known as an efficient tool to analyze characteristics of motion behavior and reconstruct control command. In this paper, motor synergy analysis for different control strategies is proposed to analyze different balance motion coordination for various levels of pushing force, and understand the coordination of human multiple joints regarding balance recovery. The spatial synergy of specific joint angles for different pushing force levels exerted on the subject's back is computed with the principal component analysis (PCA) to evaluate the adaptive balance motion response patterns and illustrate the improvement of balance robustness through the switch of joint coordination. Therefore, the switch of postural coordination over multiple joints in balance recovery movements was analyzed to better understand the mechanism of balance strategy generation in this study.