Fuzzy logic control for flexible link robot arm by singular perturbation approach

This work addresses flexible-link robot arm control using fuzzy logic, and a singular perturbation approach. A singular perturbation approach is introduced to derive the slow and fast subsystems and thus reduce the effect of spillover. Consequently, a two-time scale fuzzy logic controller will be applied for such systems. The fast-subsystem controller damps out the vibration of the flexible structure by the optimal control method. Thus, the slow-subsystem fuzzy controller dominates the tracking of the trajectory. The stability of the internal dynamics was guaranteed by adding a boundary-layer correction based on singular perturbations. The first investigation of hybrid LQ-fuzzy controller yielded a favorable output response for the flexible link robot arm than does the traditional outer-loop PD control with the boundary layer stabilizer. The fuzzy control method is reliable and robust. © 2002 Elsevier Science B.V. All rights reserved.