Modelling and identification of differential pressure cells

This paper describes the development of a mathematical model of a differential pressure cell, and its application in MATLAB. The model is also examined in SIMULINK, for the purposes of comparison of the model with the real world. Furthermore we also describe the application of a system identification method, using a multifrequency binary test signal, for comparison with the mathematical model. The method is applied to a pneumatic differential pressure cell. The exploration of the mathematical model shows that whilst the majority of the subsystems are nonlinear, they can adequately be approximated by Taylor polynomials. This facilitates the modelling of the subsystem elements as linear agents. The identification results show that the cell, composed of three main components, the diaphragm, pilot relay flapper/nozzle and the feedback bellows, has an overall first order linear response.