Figure 9

Evolution of the correlation coefficient, relative phase influenced by different hip stiffness values 25, Â 50, Â 75, Â 100, Â 125, Â 150, Â 175, and 200Â [Nm/rad], respectively. Energy consumption penalization parameter \(\gamma\) in Eq. (6) is 20. The motion amplitude A of target point in Eq. (5) is 0.1 [m]. Ankle stiffness remains 25Â [Nm/rad]. And the motion tracking frequency f of target point in Eq. (5) is 0.5Â [Hz].