Force control in piezoelectric microactuators using self scheduled H∞ technique.
Résumé
In micromanipulation and microassembly tasks, the manipulated micro-objects do not always have the same characteristics, such as compliance. Thus, both the static and dynamic models representing the force behavior respect to input sollicitations depend on the characteristics of of the manipulated micro-object. As a result, it is hard to synthesize a single controller able to ensure desired performances for all set of micro-objects, especially when their compliance range is very large. In this paper, we propose to model and control the manipulation force applied by piezoelectric microactuators by using a parameter dependent approach such that desired performances are ensured for all kind of manipulated objects. The resulting controller is said self-scheduled and easy to implement from numerical point of view. First, we derive a model that is dependent on the characteristics of the manipulated micro-object. The strong hysteresis nonlinearity of the piezoelectric microactuator was compensated and the derived model is therefore linear. Afterwards, we design a self-scheduled controller using H technique. In order to ensure the desired performances (micrometric accuracy, tens of millisecon∞d of settling time) for any manipulated micro-objects, a parameter dependent controller is designed respect to the continuum of models. Finally, the efficiency of the proposed design procedure will be illustrated from experimental results.
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