The Parallel Approach to ForcePosition Control of Robotic Manipulators

Abstract

Forcdposition control strategies provide an effective framework to deal with tasks involving interaction with the environment. In this paper the parallel approach to forcdposition control of robotic manipulators is presented. It allows a com- plete use of the available sensor measurements 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 force 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 unplanned collisions. A dynamic foreelposition parallel control law is presented and its performance in presence of an elastic environment is analyzed; simplification of the dynamic control law is also discussed leading to a PID-type parallel controller. Two case studies are worked out that show the effectiveness of the approach in application to an industrial robot.