THE PARALLEL APPROACH TO FORCE POSITION CONTROL OF ROBOTIC MANIPULATORS

Force/position control strategies provide, an effective framework to d eal with tasks involving interaction with the environment. In this pap er the parallel approach to force/position control of robotic manipula tors is presented. It allows a complete use of the available sensor me asurements by operating the control action in a full-dimensional space without using selection matrices. Conflicting situations between the position and force tasks are managed using a priority strategy: the fo rce control loop is designed to prevail over the position control loop . This choice ensures limited deviations from the prescribed force tra jectory in every situation, guaranteeing automatic recovery from unpla nned collisions. A dynamic force/position parallel control law is pres ented and its performance in presence of an elastic environment is ana lyzed; simplification of the dynamic control law is also discussed lea ding to a PID-type parallel controller. Two case studies are worked ou t that show the effectiveness of the approach in application to an ind ustrial robot.