The application of the method of simultaneous stabilization to the control of a nonlinear servo valve

The method of simultaneous stabilization is used to design a single linear compensator that stabilizes a servo valve with significant nonlinear dynamics. The servo valve is part of an automotive exhaust gas recirculation system. Linear models of the response of a servo valve at distinct operating points are developed using the actual hardware. A simultaneous stabilizing compensator (c_ss) is designed based on these models and implemented as an analog controller. The performance of the compensator is compared to results previously achieved using a conventional PI control scheme. As a result of the c_ss control's ability to stabilize the plant for small valve openings, the minimum gas flow rate achievable is improved by a factor of five when compared to conventional PI control, and valve response at high flows does not deteriorate. Several techniques for applying the method of simultaneous stabilization to real problems are presented