Adaptive control of a flexible-link mechanism using an energy-based approach

The aim of any control scheme for a flexible link mechanism is that of ensuring that the controlled system performs a fast and accurate positioning while exhibiting small vibrations. Aiming at achieving these goals, in this paper an adaptive controller is proposed for a four-bar flexible link mechanism. The controller is obtained by superposing a PD position controller and an adaptive proportional vibration controller. The position controller is a priori tuned, basing on the physical features of the flexible mechanism. The vibration controller, instead, is a proportional controller whose gains are adaptively tuned to ensure good performances even when working conditions change and abrupt disturbances affect the system functioning. The controlled-system stability is formally proved by means of an energy-based approach. Moreover, the controller performances are illustrated by means of simulations and compared to the performances of analogous nonadaptive control schemes.