Active Suspension Control Based On Cascade Nonlinear Active Disturbance Rejection Strategy Research

Due to the complex driving conditions of the emergency rescue vehicles,the uneven unstructured road surface makes the load borne by the active suspension uncertain and time-varying.In addition,the electro-hydraulic servo control active suspension has a high degree of nonlinearity,and it is difficult to establish an accurate control object model.Therefore,in order to solve the problem of low control precision caused by the internal and external interference of the active suspension of emergency rescue vehicles and improve vehicle ride comfort,the research contents of this paper are as follows :Firstly,an active suspension control strategy based on the active disturbance rejection control is proposed,which connects the displacement control loop and the speed control loop in series.Both control loops adopt an improved active disturbance rejection controller.The displacement control loop is used to reduce the disturbance caused by road uncertainty,time-varying characteristics and other unknown external factors.The speed control loop is used to reduce the disturbance caused by the unmodeled part,the coupling part and the parameter perturbation in the loop,and improve the displacement and speed tracking accuracy.Secondly,a control strategy of the vehicle cascade active suspension is proposed,which can decouple the vertical,roll and pitch motion of the vehicle active suspension,and the cascade sliding mode active disturbance rejection controllers of vertical,roll and pitch motion are designed respectively to optimize the vehicle controller parameters.The simulation results show that when the vehicle is driving on a random road,the root mean square values of the vertical,pitch and roll accelerations of the active suspension with cascade active disturbance rejection control are reduced by about 32.57%,34.56% and 46.83% respectively compared with the passive suspension.Finally,the suspension unit and sample vehicle test platform are built to carry out the controller tracking test and the convex hull road driving test.The experimental results show that the cascade active disturbance rejection controller improves the tracking accuracy by about2% and the response time by about 5% compared with the general nonlinear active disturbance rejection controller.Compared with the passive suspension,the peak values of body vertical displacement,pitch angle and roll angle under the cascade active disturbance rejection controller are reduced by about 26.46%,29.37% and 27.28%,respectively,which improves the control accuracy of vehicle suspension and the vehicle ride comfort.