End-point control of a flexible-link manipulator: theory and experiments

This paper focuses on the tip-position control of a single flexible link which rotates in the horizontal plane. The dynamic model is derived using a Lagrangian assumed modes method based on Euler-Bernoulli beam theory. The model is then linearized about an operating point. An output feedback control strategy that uses the principle of transmission zero assignment achieves tracking for this nonminimum phase linear time-invariant system. The control strategy consists essentially of two parts. The first part is an inner (stabilizing) control. Loop that incorporates a feedthrough term to assign the system's transmission zeros at desired locations in the complex plane, and a feedback term to move the system's poles to appropriate positions in the left-half plane. The second part is a feedback servo loop that allows tracking of the desired trajectory. The controller is implemented on an experimental test-bed.