Modelling a pneumatic servo positioning system with friction

Treats the problem of modelling and identification of the various elements of a pneumatic servo positioning system with the aim of constructing a complete and effective model that can be used for simulation and accurate control of such systems. Particular attention is paid to two important elements that manifest a strong nonlinear behaviour, viz, air flow and friction. In the first instance, an empirical model connecting the pneumatic valve´s driving voltage, the pressures upstream and downstream, and the flow is hypothesised based on the nozzle formula. With this model, the flow function is then systematically identified. As regards friction, the Leuven model structure is used as basis for identification. Here, the two basic friction regimes, viz. presliding, with its hysteresis behaviour, and gross sliding are well exposed and their essential parameters identified