Adaptive Admittance Control: An Approach to Explicit Force Control in Compliant Motion

‘J’his paper addresses the problem of controlling a mani]mlator in compliant motion while in contact with an environment having an unknown stiffness. Admittance control is used as an czplzczt force control sc}]eme in which a force setpoint is specified and is tracked by the force compensator. Two adaptive PID and 1>1 force colnpcnsators arc propcrscd. The compensators ensure robust tracking of step force setpoints and rejection of constant disturbances. Since the environmental stiffIICSS can typically vary by several orders of magnitude, compensator adaptation is used to ensure a stable and uniform systcm performance. Dynamic simulation rcSU1 ts for a 7 DOI{’ Robotics ILesearc}l arm arc presented to demonstrate the eflicacy of the proposed admittance co~)trol schcmc in executing contact tasks. 1