Desired Compensation Nonlinear Cascade Control of High-Response Proportional Solenoid Valve Based on Reduced-Order Extended State Observer

With the gradual improvement of microprocessor, various nonlinear controllers are successfully applied in the electronic hydraulic system (EHS). The high-response proportional solenoid valve (HPSV), as the key component of many middle-end and high-end EHS, attracts many researchers' close attention. This paper focuses on the method to get a strong robustness and high-performance controller for HPSV. In general, the full-state feedback condition of nonlinear cascade control (NC) cannot be easily satisfied in the industrial application. Therefore, the reduced-order extended state observer (RESO) is proposed to estimate the unmeasured state variables and the lumped uncertainties (mainly the unmodeled uncertainty and disturbance). Then, this paper presents an NC-based RESO for HPSV. To obtain an excellent control performance of NC, the desired compensation is adopted to reduce the interference of measurement noise, especially when the tracking error is reduced to the same order as the measurement noise. The system stability and error boundedness of the desired compensation NC based on RESO (DCNCRESO) are proved theoretically in this paper. To validate the effectiveness of DCNCRESO, several different types of experiments are carried out under different working conditions. Even when the supply pressure has great fluctuation, the DCNCRESO still behaves well, which manifests its strong robustness.