Experimental modeling and control design of a linear hydro-pneumatic position system

Abstract

Although hydro-pneumatic systems are extremely important nowadays, the publications around this subject involving mathematical modeling and control are too small. The aim of this work is to study such systems by presenting an experimental system identification procedure and the control design. It is shown that modeling can be easily done in the time domain being air compressibility modeled as a dead-time. The controller was designed by using both, numerical optimization and optimal control theory. The first design approach solves a numerical model-matching problem where the closed-loop dynamics are forced to follow a first-order transfer function response. The second design approach takes both, dead-time and the PWM modulator dynamics were considered as uncertainties of the nominal mathematical model and the controller was obtained by mapping the optimal control law into a PID structure.