Open-loop control for 2DOF robot manipulators with antagonistic bi-articular muscles

This paper investigates open-loop control, which does not need the joint angles and velocities, for two degree of freedom(2DOF) robot manipulators with antagonistic bi-articular muscles which are passing over adjacent two joints and acting the both joints simultaneously. The manipulator dynamics of three muscle torques, we call the bi-articular manipulator dynamics, is constructed in order to design the control input. Stability analysis with respect to our proposed control law is discussed based on the Lyapunov method. Our approach is inspired by the fact that humans do not measure the joint angles and velocities explicitly, Finally, simulation results are shown in order to confirm the proposed method and given a design procedure in order to assign the tuning parameter.