Experimental and simulation studies of hard contact in force reflecting teleoperation

Experiments and simulations of a single-axis force-reflecting teleoperation system have been conducted to investigate the problem of contacting a hard environment and maintaining a controlled force in teleoperation in which position is fed forward from the hand controller (master) to the manipulator (slave), and force is fed back to the human operator through motors in the master. The simulations, using an electrical circuit model, reproduce the behavior of the real system, including effects of human operator biomechanics. It is shown that human operator properties, which vary as a result of different types of grasp of the handle, affect the stability of the system in the hard-contact task. The effect of a heavier grasp on the handle is equivalent to increased hand-controlled velocity damping in terms of the systems stability in the contact task, but control system damping sufficient to guarantee stable contact results in perceptible sluggishness of the control handle´s response in free motion. These results suggest that human operator biomechanics must be taken into account to guarantee stable and ergonomic performance of advanced teleoperators