Chapter 7 - Sensor Referenced Impact Control in Robotics

Abstract

This chapter discusses the problems in the area of impact control and force regulation. It addresses the issues of force regulating and contact transition stabilizing control or so-called impact control. Impact control is required in most assembly tasks involving the interaction of the manipulator and the workpiece. For workpieces with low tolerance, force feedback is necessary to reduce the effect of the uncertain location and unknown stiffness of the environment. In a general contact operation, a certain approach velocity is needed for high productivity resulting in a collision with the contact surface. Collision is considered as a dangerous phenomenon compromising the safety of the equipment. The chapter studies a robust force control design via positive acceleration feedback combined with a switching control strategy for the impact control and force regulation. The transient force response during impact is controlled to limit the peak impact force. The system can be stabilized after a finite number of switches. The output forces in the contact directions and the output positions in the moving directions can be regulated simultaneously after contact is established. Accidental loss of contact can be corrected automatically. A great amount of effort will be spent on the stability analysis, leading to a theoretical foundation in the impact control area.