PID - Gain Scheduling Controller for a Robot Manipulator

Abstract

This paper presents the implementation of an adaptive PD - Gain Scheduling controller for a six-degree-of-freedom robot manipulator. Uncoupled PD controllers are proposed for each joint where each single manipulator joint is controlled independently of the others. The gain scheduling technique enables the controller to adapt on-line the PD parameters depending on the operation conditions (essentially the robot arm position). The nonlinear dynamic model of the robot arm is then linearized discarding non-linear terms which are considered as model uncertainties, and a continuous adaptation law for the PD controller parameters is proposed. The overall control strategy can be regarded as composed by a non-linear transformation (adaptation law), followed by a linear PD regulator. This simple technique offers promising results with respect to the traditional worst-case PD design.