Figure 2.

Motor control system (feedforward current compensations are provided to deal with inertial-related, speed-related and load-related changes in the prosthetic system). $L_m$ and $R_m$ are the inductor and the resistor of the motor, and $J_m$ and $b_m$ are the moment of inertial and damping of the motor and transmissions; $K_{\mathrm{M}}$ and $K_N$ are the torque constant and the speed constant of the motor, respectively; $K_{\omega }$, $K_{\tau }$ and $K_{\alpha }$ are corresponding gains of feedforward current compensations; $T_p$ is the needed actuating torque of the prosthetic knee, and $\mathsf{\Delta }{T}_P^{Calc}$ is the calculated prosthetic torque changes by real-time inverse dynamics of the prosthetic knee.