Optimal Fuzzy Logic Controller for a Flexible Robot

Abstract

†Operational problems with robot manipulators in space relate to several factors, one most importantly being structural flexibility and subsequently significant difficulties with the control systems, especially, for position control. This paper presents a comparison of fuzzy logic system (FLS) controllers to determine an optimal design for tracking the endpoint of a two-link flexible robot. The dominant assumed mode of vibration for an EulerBernoulli cantilever beam is coupled with the nonlinear dynamics for rigid links to form an Euler-Lagrange inverse flexible dynamics robot model. A Jacobian transpose control law is adapted by a FLS with link deformation inputs and a single variable output. Simulation results for three, five, seven and nine triangular and Gaussian membership functions are compared to identify an optimal design for best tracking control and least computation time. Results show the optimal choice of FLS is three triangular membership functions at 14 min 51 sec tracking time.