MPC-based admittance control for robotic manipulators

Robotic applications involving environmental interaction require control structures that go beyond traditional position control. One approach to handle interaction forces is admittance control. Therein, position or speed reference values are modified based on interaction forces. To this end, the underlying position control scheme, widely used in industrial manipulators, is augmented with an additional admittance control loop. It is well known that such approaches raise stability issues in the interaction with stiff environments (termed contact stability). As a consequence, in traditional admittance control, the speed of operation needs to be reduced in order to prevent excessive contact force magnitudes and to ensure stability. In this paper, we propose an MPC-based admittance control scheme to circumvent both and discuss its properties and difficulties for practical use.