Online Optimizing Positioning Control With Model Error Compensator for LEGRV System

In this article, a precision positioning control approach of a linear exhaust gas recirculation valve (LEGRV) system using online optimization technique is proposed. As both dynamics and nonlinear factors, including hysteretic features, are inherent in LEGRV systems, the modeling of system is not an easy process. In order to avoid the complex obstacle of modeling, in this method, a simplified model, for e.g., linear or linearized dynamic model, is developed to approximate the essential motion feature of pintle position of the linear valve. For compensating the effect of model uncertainty caused by unmodeled nonlinear and dynamic factors, a model error compensator (MEC) is introduced. Then, an online optimizing positioning control (OPC) scheme is applied to the control of pintle position of valve. In this control scheme, the estimated gradient of MEC with respect to control variable is also included in the control strategy to suppress the influence of model uncertainty. Considering the effect of nonsmoothness of hysteresis inherent in the system, a nonsmooth optimization-search method based on the technique of generalized gradient is proposed. Afterward, the stability analysis of the OPC+MEC system is presented. Finally, the experimental results to evaluate the performance of proposed control method are presented.