Experimental Control of Flexible Robot Manipulators

摘要

An experimental study of several control strategies for flexible manipulators has been presented in this chapter. As a first step, the dynamical model of the system has been derived from a general multi-link flexible formulation. If should be stressed the fact that some simplifications have been made in the modelling process, to keep the model reasonably simple, but, at the same time, complex enough to contain the main rigid and flexible dynamical effects. Three control strategies have been designed and tested on a laboratory two-dof flexible manipulator. The first scheme, based on an LQR optimal philosophy, can be interpreted as a conventional rigid controller. It has been shown that the rigid part of the control performs reasonably well, but the flexible deflections are not well damped. The strategy of a combined optimal rigid-flexible LQR control acting both on the rigid subsystem and on the flexible one has been tested next. The advantage that this type of combined control offers is that the oscillations of the flexible modes attenuate considerably, which demonstrates that a strategy of overlapping a rigid control with a flexible control is effective from an experimental point of view. The third experimented approach introduces a sliding-mode controller. This control includes two completely different parts: one sliding for the rigid subsystem and one LQR for the fast one. In this case the action of the energetic control turns out to be effective for attracting the rigid dynamics to the sliding band, but at the same time the elastic modes are attenuated, even better than in the LQR case. This method has been shown to give a reasonably robust performance if it is conveniently tuned. The IDA-PBC method is a promising control design tool based on energy concepts. In this chapter we have also presented a theoretical and experimental study of this method for controlling a laboratory single flexible link, valuing in this way the potential of this technique in its application to under-actuated mechanical systems, in particular to flexible manipulators. The study is completed with the Lyapunov stability analysis of the closedloop system that is obtained with the proposed control law. Then, as an illustration, a set of simulations and laboratory control experiments have been presented. The experimented