Hybrid control for robotic manipulators

Abstract

The proportional-integral-derivative (PID) controller is still the most dominant form of feedback control in use because of its simplicity and efficiency to produce powerful solutions for most cases of industrial processes. However, the PID controller may be inadequate for nonlinear and non-minimum phase systems since the design of the controller is based on constant gain values. On the other hand, many advanced control methods have been proposed to overcome the limitations of the PID controllers. These control methods have highly dynamic structures to minimize the resultant error by optimizing the control signal, but stability is their common problem. This study integrates the classical proportional-derivative (PD) control with the self-tuning adaptive control in order to have a stable and dynamic control structure. The integral part (I) of PID is replaced by explicit self-tuning control to improve the performance of the proposed controller. Some experimental results on a hydraulic robot are presented for validation of the proposed concept of hybrid control.