MODELLING AN ELECTRO-HYDRAULIC POPPET VALVE

This paper develops the dynamic modelling of a novel two-stage bidirectional poppet valve and proposes a simplified model that is more suitable for control purposes. The dynamic nonlinear mathematical model of this Electro-Hydraulic Poppet Valve (EHPV) is based on the analysis of the interactions among its three internal systems: the mechanical, hydraulic, and electromagnetic system. A discussion on the employed experimental methodology is included along with the validation of this model. When the pressure differential across the valve is sufficiently high and does not vary considerably, the model for this valve can be simplified substantially. More specifically, the EHPV can be modelled as a linear second order system with a static input nonlinearity. This nonlinearity is realized from the valve's steady state characteristics. The advantage of this separation between valve dynamics and nonlinearities is that an inverse linearisation approach (to cancel the nonlinearity) can be used to facilitate the control task for the valve.