Modeling and Simulation of a Proportional Pneumatic Valve with Positioner

Abstract

This study presents a comprehensive investigation into the modeling, system identification, and robust control design of an electro-pneumatic valve positioning system, with the objective of enhancing precision and reliability in industrial automation applications. The research begins with a foundational examination of industrial valve principles, classifications, and operating mechanisms, highlighting their indispensable role in fluid flow regulation across diverse process sectors. The historical trajectory of valve positioners is traced from early mechanical linkages and force-balance pneumatic devices to modern digital and smart positioners equipped with on-board diagnostics and fieldbus communication. Central to this work is the development of analytical transferfunction models for the double-acting pneumatic cylinder, the directional control valve, and the solenoid coil assembly, capturing the dominant dynamics that govern the electro pneumatic positioning loop. To accommodate the inherent nonlinearities of the physical plant ,including compressible airflow, mechanical friction, and valve hysteresis, a closed loop system identification approach is adopted, driven by a persistently exciting signal generated by an STM32 microcontroller. The results demonstrate the efficacy of the proposed modeling and identification framework as a foundation for high fidelity control design. This research contributes to the advancement of automated process instrumentation by establishing a structured methodology for the analysis and optimization of electro-pneumatic positioners, while paving the way for future developments in intelligent valve control and predictive diagnostics.