Nonlinear tip-position tracking control of a flexible-link manipulator: theory and experiments

This paper presents an observer-based inverse dynamics control strategy tha t results in small tip-position tracking errors while maintaining robust cl osed-loop performance for a class of multi-link structurally flexible manip ulators. This is done by defining new outputs near the end points of the ar ms as well as by augmenting the control inputs by terms which ensure stable operation of the closed-loop system. As part of the control design, a nonl inear observer is introduced to estimate the rates of change of flexible mo des. Experimental results are given for the case of a two-link manipulator with a flexible link that further confirm the theoretical and simulation re sults. (C) 2001 Elsevier Science Ltd. All rights reserved.