Pressure Control of Pneumatic Systems with a Non-Negligible Connection Port Restriction

P. Bigras

Keywords

Pneumatic systems, nonnegligible restriction, pressure tracking, feedback linearization, linear matrix inequalities

Abstract

This work presents an approach to the design of a pressure-tracking controller for a pneumatic cylinder system for which the connection port comprises a non-negligible restriction. The pressure chamber of this system is diffcult to control because the servovalve and the connection port together constitute a double restriction. Moreover, the pressure in the cylinder cannot be directly measured and cannot be expressed as an explicit function of measurable pressure. A model of this system can be approximated using the singular perturbation approach. The tracking control problem is further formulated as a stabilization of a nonlinear time-varying system. The control law is divided into two stages: the first stage linearizes the system, and the second stabilizes the tracking error, which is formulated as a linear time-varying differential equation. The gains of the stabilization control law are found using the Linear Matrix Inequality (LMI) method. Simulation and experimental results show that the proposed control system performs well.

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