A Robust PID Control Algorithm for a Servo Manipulator with Friction

A servo manipulator system has been developed for remotely handling radioactive materials in a hot cell [1]. Unlike a robot manipulator, a servo manipulator is monitored and controlled by an operator all the time. A robot manipulator performs a taught or programmed task without an operator. Generally, a servo manipulator consists of a master arm and a slave arm. The slave arm is a device for working instead of people such as lifting and handling an object, and the master arm is an input device for the slave arm. Servo motors have generally been used to control or drive a servo manipulator. They are reliable driving power sources for servo control problems. In this paper, practical problems related with a servo motor are discussed. During the development of a servo manipulator, a control problem of a servo motor has been an important issue. The practical problems are parameter uncertainty and frictional effect. This paper aims to discuss the practical problems and the process of identifying and reducing the effects of parameter uncertainty and friction. An extensive survey of friction has been introduced in [2]. Parameter uncertainty of a servo motor and friction affect the tracking performance. A poor tracking, a limit cycle and windup may occur. The two problems have been dealt with for many years and many remedies have been proposed. Among them, a simple and effective one is applied to the servo manipulator control and the results are presented.