Passive bilateral teleoperation of a hydraulic actuator using an electrohydraulic passive valve

A passive control scheme for the bilateral teleoperation of a electrohydraulic actuator and a motorized joystick is proposed. The overall system enables a human operating a motorized joystick to feel as if he is manipulating a rigid mechanical tool with which the work environment is also in contact. By ensuring that the closed loop system behaves like a passive two port device, safety and stability when coupled to other systems are improved. The control scheme is developed by first using previously developed active feedback to passify a four way proportional directional control valve, and then by the design of an intrinsically passive teleoperation controller. The coordination error between the joystick and the hydraulic actuator converges to zero for sufficiently low manipulation bandwidth. Experimental results verify the characteristics of the control scheme.