Force and position fuzzy control: A case study in a Mitsubishi PA10-7CE robot arm

Abstract

Too many research works have focused on the problem of control of robot manipulators while executing tasks that do not involve the contact forces of the end-effector with the environment. However, many tasks require an interaction of the manipulator with the objects around it. For the correct performance of these tasks, the use of a force controller is essential. Generally, the control objective during the contact is to regulate the force and torque of the manipulator's end-effector over the environment, while simultaneously regulating the position and orientation (i.e., the pose) free coordinates of the manipulator's end-effector. Many works have been presented on this topic, in which various control strategies are presented; one of the most relevant methods is the so-called hybrid force/position control; this scheme has the advantage of being able to independently control the force in constrained directions by the environment and the pose along unconstrained directions. This work analyzes and implements the hybrid force/position control using a fuzzy logic control method, since the fuzzy control provides a solution for nonlinearities, high coupling, and variations or perturbations. The system employed is the Mitsubishi PA10-7CE robot manipulator, which is a robot of 7 degrees of freedom (DOF), but in this work, it is only used as a 6-DOF manipulator, equipped with a 6-DOF force/torque sensor in the end-effector.