Fig. 12
From: Safety-enhanced control strategy of a power soft robot driven by hydraulic artificial muscles
Block diagram of the variable second-order impedance control. The outer loop outputs the internal pressure difference equals \(\Delta P_{\text{act}} +\Delta P_{\text{pos}} +\Delta P_{\text{sel}} \), and the desired internal pressure of both muscles is shown in Eq. (9). Each inner loop includes a braking controller; which controls whether the servovalve is closed or not; the control law is shown in Eq. (13)