| In recent years,with the continuous development of the economy,the logistics and transportation requirements increase continually,the road network structure and the scale of road transportation expand constantly.With the development of science and technology,the requirements of peoples become higher for comfort during vehicle driving.The traditional passive suspension is difficult to meet the driving comfort requirements of vehicles under different driving conditions.The research group cooperated with a vehicle corporation to carry out the research of semi-active suspension of the long-distance logistics truck cab.In this paper,the hardware and software integration and control algorithms of semi-active suspension based on CDC damper are carried out.Models of semi-active suspensions are built and used for the simulations.And the control strategies are verified in the bench simulation test and the real vehicle test.The main research contents of this paper are listed as follows:(1)To establish the semi-active suspension model and vehicle dynamics model.According to the parameters of the CDC damper provided by the manufacturer,the mathematical model of the damper is established.And the inertial links are introduced to simulate the dynamic properties of the damper.Based on the real vehicle data,the quartervehicle model and the 12 degrees of freedom vehicle dynamics model are built to provide the simulation model basis for the research of the control strategy.(2)To research the semi-active suspension control strategies.Referring to ISO2631-1997(E),the weighted RMS was selected as the evaluation criterion for driving comfort.Based on the frequency characteristics of the vibration system,the advantages and disadvantages of each classical control strategy in the semi-active control system are analyzed.For the tremor phenomenon of classical control algorithms,a nonlinear damping curve control strategy is proposed and simulated in MATLAB/Simulink.The result shows that this control strategy can effectively reduce the vibration in the full frequency band without producing a strong tremor phenomenon.The effect of the integration error on the control effect is analyzed.And an improved one-sensor control strategy based on the IIR filter is proposed.This control strategy requires a small number of sensors,small computation volume,and small computing power requirements for hardware.These advantages can help to reduce costs.And it is conducive to the widespread promotion of semi-active suspension.The simulation result shows that this control strategy can effectively avoid the influence of the integration error on the control effect,so that reduce the weighted RMS value of the acceleration.(3)To conduct bench and real vehicle test.Base on the preliminary research of the research group,the reasons for the serious fever of the current closed-loop control scheme are analyzed.And the improvement scheme is proposed and implemented.A semi-active quarter vehicle model test bench is built.To verify the effectiveness of the improved onesensor control strategy.The vibrations generated as the vehicle passes through road surfaces are simulated by the electromagnetic vibration generator system.The result shows that this control strategy is able to effectively distinguish the frequency components of the vibrations.And it can select the suitable damping force of the damper according to the frequency components.The semi-active suspension system of the cab is built base on a long-distance logistics truck.And the real vehicle test is carried out.The result shows that the improved one-sensor control strategy can achieve the target of high vibration isolation coefficient at high frequency and strong inhibitory resonance ability at low frequency.This control strategy can effectively reduce the vibration of the vehicle cab in x-direction and zdirection.The evaluation criterion of the x-direction and z-direction is optimized by 19.5%and 10.2% respectively. |
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