FORCE AND MOTION CONTROL OF A SINGLE FLEXIBLE MANIPULATOR LINK

The problem of controlling the contact force exerted by the tip of a s tructurally flexible manipulator link on its environment is addressed. Control strategies which employ an adaptive long range predictive con trol algorithm based on the generalized predictive control (GPC) algor ithm of Clarke et al. (Automatica, 23(2): 137-148, 1987) are developed and demonstrated. A simulation of a single flexible manipulator link contacting a deformable surface has been utilized to evaluate the cont rol strategies. The simulation includes a beam-type continuum model of the manipulator link and a lumped-parameter model of the surface dyna mics in the region of contact. Simulation results are presented which demonstrate the performance of an adaptive version of the force contro ller. The controller is adaptive in the sense that the system model is identified on-line using a recursive least squares (RLS) algorithm. A lso presented are some results and a discussion on the problem of achi eving stable force control after a contact event in which the link has a significant approach velocity. A control strategy which uses sensor information to predict the initial contact force transient and tempor arily modifies the force setpoint during this transient is proposed an d demonstrated in simulation.