A force commanded impedance control scheme for robots with hard nonlinearities

This paper investigates a hybrid impedance control scheme that utilizes a desired force, rather than a desired position, as the commanded variable. This scheme is examined for a manipulator system in the presence of inherent hardware nonlinearities, and it demonstrates improved performance with respect to an explicit force control structure of a similar degree of robustness. Theoretical conclusions are supported experimentally on a customized Puma 560 Robotic Testbed facility, developed by the authors.