Experimental results on tracking control of a flexible-link manipulator: a new output re-definition approach

The problem of controlling the tip position of a flexible-link manipulator is considered. The control strategy is based on an output re-definition approach which is applicable to a class of non-minimum phase nonlinear systems whose nonlinearities appear in output terms in their input-ouput mappings and are open-loop stable. The controller is composed of a stabilizing joint PD controller and an output re-definition tracking controller. The output re-definition scheme is based on modifying the zero dynamics of the system using a stable/anti-stable factorization. The controller is then designed based on the new output whose zero dynamics are stable and can be inverted. Experimental results are also presented to show the effectiveness of the proposed control scheme as compared to a PD controller.