Abstract:

Nonlinear time series analysis and its application in the quantification of dynamic stability were discussed,and VICON MX 3D motion capture system was used to collect the dynamic data of hip, knee and ankle when human were walking on treadmill at 40%, 60%, and 80% of the Froude velocity. Matlab was used to realize the calculation of delay time τ through CC method and the calculation of embedding dimension m through falsenearestneighbor analysis, and finally the largest Lyapunov exponents λmax under different speeds was calculated.Then λmax was adopted as a quantified index for stability to study the relationship between speed and dynamic stability. The smaller λmax valued, the better stability was. The results show that λmax increases linearly and stability decreases with the increase of speed.

Key words: engineering bionics, gait, stability, Lyapunov exponents