Vehicle Semi-Active Suspension Control Strategy And Optimization Research

Damping force controllable electronically controlled suspension can effectively improve the comfort of the vehicle,and has the advantage of low cost,becoming an important direction for the development of semi-active suspension.By formulating a reasonable and efficient control strategy for semi-active suspension system,the core damping adjustment elements of the vehicle suspension system can be highly controllable to achieve continuously adjustable damping;it is necessary to optimize the semi-active suspension control strategy,improve the damping performance of the semi-active suspension system,meet the dynamic requirements of the vehicle in multiple operating conditions,and then improve the smoothness and handling stability of the vehicle.As the main representative of electronically controlled suspension,CDC(Continuous Damping Control)damper has the advantages of low cost,high controllability,high stability and superior vibration damping performance.This thesis takes the semi-active suspension CDC damper as the research object,through the CDC damper demonstration function characteristic test,establish the Adams car whole vehicle model,develop the semi-active suspension control strategy,in order to improve the vehicle smoothness and handling stability as the goal,based on NSGA-Ⅱ algorithm to carry out multi-objective collaborative optimization of the semi-active suspension control strategy.The main research contents are as follows:(1)By testing the power characteristics of the CDC damper,the influence of the PWM duty cycle and PWM frequency of the damper solenoid valve on the damping force is clarified,and an accurate forward and reverse model of the CDC damper is established to provide data support for the formulation of a reasonable damping continuously adjustable semi-active suspension control strategy.(2)By establishing Adams nonlinear multi-body dynamics model and fourteen-degree-of-freedom vehicle dynamics model,and verifying the wheel vertical load consistency under steering angle step condition,thus ensuring the correctness of the Adams whole vehicle model and laying the foundation for subsequent verification of the effectiveness of the semi-active suspension control strategy;establishing an accurate and reasonable road surface model based on the actual driving surface of the vehicle,including convex bale road surface,belgian stone road surface and serpentine pile winding vehicle trajectory control;combining the established Adams whole vehicle model to carry out three typical conditions simulation of speed bump condition,high frequency road excitation condition and serpentine pile winding condition,and to develop different evaluation indexes;by changing the compression damping and rebound damping of the shock absorber,the influence of the damping factor of the shock absorber on the vehicle performance is analyzed.(3)To improve the damping performance of the semi-active suspension system,a semi-active suspension control strategy with continuously adjustable damping is developed,and the design of the semi-active suspension controller is completed using Simulink;a joint simulation model of Adams car and Simulink is established to analyze the effect of the semi-active suspension control strategy with the peak-to-peak value and attenuation of the deceleration zone condition,the root mean square value of the ver tical acceleration of the high-frequency road excitation condition and the lateral tilt angle of the serpentine pile winding condition as evaluation indexes,and to provide a decision basis for the optimization of the subsequent control strategy.(4)In order to realize the excellent matching between the CDC damper control strategy and the overall vehicle dynamics performance,a control strategy collaborative optimization platform is built based on the multidisciplinary optimization software ISIGHT,Adams car and MATLAB/Simulink;the multi-objective collaborative optimization is carried out with the subordinate degree function of the control strategy as the design variable,the frequency domain peak under typical operating conditions as the constraint,and the time-domain evaluation index as the optimization target;the optimization results show that the semi-active suspension control strategy optimized by NSGA-Ⅱ algorithm meets the performance requirements of various typical operating conditions of the vehicle and improves the smoothness and handling stability of the vehicle.The research in this thesis further improves the comprehensive performance of the semi-active suspension system,which is an important reference application for CDC damper product development and practical engineering applications.