LQR and PID Control Design for a Pneumatic Diaphragm Valve

Abstract

This work demonstrates the design and compares the performance of two different digital control techniques for a modeled pneumatic diaphragm valve. The valve model is derived using first-principles modeling, the Karnopp friction model and approximates the I/P converter dynamics with a first order filter. The digital PID and LQR controllers were chosen to compensate the valve friction. A proposed contribution is to implement a digital LQR control using the Bryson rule and the Pincer technique to tune the matrices Q and R based on requirements response, maximum deviation of states variables and control effort. The robustness of the LQR controller compared to the PID controller is presented in this paper.