Two-time scale fuzzy logic controller of flexible link robot arm

Abstract

A flexible link arm is a distributed parameter system of infinite order, but due to onboard computer limitations, sensor inaccuracy, and system noise, it must be approximated by a lower-order model and controlled by a finite-order controller. The main object of this paper is concentrated on the hierarchical fuzzy logic by the singular perturbation approach for flexible-link robot arm control. A composite control design is adopted. Therefore, a two-time scale fuzzy logic controller will be applied for such system. In this paper, the fast-subsystem controller will be damp out the vibration of the flexible structure by two hierarchical fuzzy logic controllers. Moreover, the other slow-subsystem fuzzy controller dominates the trajectory tracking. We guarantee the stability of the internal dynamics by adding a boundary-layer correction based on singular perturbations. In addition, various case studies are given in illustration to verify the control algorithm. It appears that the fuzzy control method is quite useful as regards reliability and robustness.