Mathematical modeling and DLQR based controller design for a non-minimum phase Electro Hydraulic Servo system (EHS)

In this paper, an Electro-Hydraulic Servo system is presented which bears the characteristics of basic Non-minimum phase (NMP) systems. Controlling problems encountered in NMP systems and optimizing the system response with optimal control strategy is the prime objective of this study. The described EHS system is mathematically modeled to obtain the discrete-time transfer function for analyzing its characteristics of Non-minimum phase system and illustrated by computer simulation using MATLAB©. Discrete Linear Quadratic Regulator (DLQR) is presented as the controller for optimal controlling of the NMP behavior of EHS system. Response of the system is studied with and without the application of the DLQR. The comparative study illustrates an improvement in system behavior which can be used for obtaining perfect tracking and position tracking control of such systems.