Hybrid control with on/off electropneumatic standard valve for tracking positioning
Résumé
This paper presents a new method of control applied in electropneumatic field. This strategy is issued from hybrid control theory recently applied in control of asynchronous or synchronous electrical motor (1, 2). The interest of these procedure concerns the possibility of controls the position of an electropneumatic piston all along the cylinder stroke with standard on/off valve. Nowadays the industrial electropneumatic process used on/off valve for point to point aim with displacement from one extremity of cylinder to the other one. When different desired positions are required the constructors used specific components issued from proportional technology: servovalve or servodistributor for example. The evolution in the automation process is moving towards a need of obtaining greater versatility and increased precision in compressed air driven equipment. This means obtaining proportional operation of the power element as a function of an electric control signal. Nevertheless, when the desired precision is near the millimetre and not very good performances are need during dynamic stage, the useful of proportional technology can be debatable. Indeed the system cost and its complexity to tune can be two drawbacks that on/off technology with the proposed algorithm, can be concurrence. Based on both the models of cylinder and valves, the hybrid control presented here determines the best state of valves by tracking reference values of the cylinder states in the state space. Then a simplified model of electropneumatic system is presented and used to synthesised hybrid control algorithm. Experimental results are presented and discussed.
Domaines
Automatique / Robotique
Origine : Fichiers produits par l'(les) auteur(s)
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