Active disturbance rejection controller for variable flow gain–proportional throttle cartridge valve

The proportional throttle cartridge valve has been widely used in heavy machine due to its fast response and huge flow rate. However, large flow impact could occur at the instant of proportional throttle cartridge valve opening, which is harmful to system stability and service life of machines. A variable flow gain–proportional throttle cartridge valve was proposed in this study to reduce the vibration of hydraulic drive system caused by the flow impact. Nevertheless, the variable flow gain introduced a strong nonlinearity, as well as a big flow force disturbance, a friction force disturbance, a flow–pressure nonlinear relationship, and a variable load stiffness which are challenges for high accurate control of spool position. Therefore, a third-order active disturbance rejection controller was developed to enhance the antidisturbance ability and improve the control precision of the variable flow gain–proportional throttle cartridge valve as well. First, the mathematical model of the variable flow gain–pr...