Abstract
The force control of an actuator was traditionally performed with motor current control. To enhance force sensitivity of the robot system, actuators with underactuated degree of freedom are proposed. Such underactuated DOF is realized by either a spring or damper in the transmission system of the actuator. This underactuated DOF fundamentally enhanced the backdrivability of the system, but introduced the complicated behavior as a drawback. The backdrivable electro-hydrostatic actuators we have been proposing were not the exception. In this paper, by using the relation of speed and output force, we propose the force control method using motor velocity control. In this method, controller is simplified and we can use collocated velocity control as an inner-loop control, which suppress uncertainty of the system and simplify the control. In this paper, we explain the control method and perform evaluation of the proposed method.
