Research And Realization Of Integrated Control On Vehicle Semi-Active Suspension And Electric Power Steering

Suspension is important part of vehicle chassis system, which is effect greatly on ride comfort. Semi-Active Suspension (SAS) is becoming the main developing direction for its advantages of controllable damping force, improve suspension performance effectively, lower cost, and so on. Electric Power Steering (EPS) relieves driving tiredness, improve handle stability and safety for its performances of energy saving, safety and environment protection. And it has become mainstream power steering technology of passenger car. SAS and EPS belong to run subsystem and steering subsystem of chassis construction separately, which common effect on dynamic performance of vehicle chassis. Therefore the research related modification the structure of suspension and power steering performance, is one of the vehicle project areas of technology hot spot topics all along.At present, control technology on solo SAS and solo EPS is mature more and more. Therefore it focus on integrated control of chassis system to improve comprehensive performance furthermore. Simple combination control of SAS and EPS cannot obtain the most superior performance for their coupling effect, so it is necessary to integrate control SAS and EPS. Therefore, research on integrated control of SAS and EPS as follows:Firstly, analysed research status of SAS, EPS and integrated control, then integrated control strategies were being introduced. Established integrated system model based on steering condition, and analysed the interaction, coordination mechanism, impact on vehicle performance of SAS and EPS.Secondly, changed traditional design and exploiture method, imported multi-agent thchnology,which is being hot spot in research field of artificial intelligence. Set up suspension agent, steering agent, system agent, and so on. Researched control strategies of agents. Framed chassis multi-agent integrated model based on hierarichal control. A new control strategy for improve vehicel dynamic self-adaptability was being put forword by intelligent behavior of agents.Thirdly, in order to proof validity and feasibility of integrated control strategy, modeled integrated model of SAS and EPS by software MATLAB & AMESim. Mechinical system models were being model in AEMSim, and control system model was being model in MATLAB/Simulink. Layered connection agents based on Multi-Agent System (MAS) theories, then combined MATLAB & AMESim to simulate integrated models, and provided references for design integrated controller and vehicel road test.Fourthly, designed MAS integrated controller based on embedded operation system ARM for realize integrated control. Implemented function of modules about input singals, control strategies, output signals and so on. Adopted fuzzy and PID strategies to control step motor of SAS agent and DC motor of EPS agent. Vehicle body acceleration was being controlled by fuzzy strategy, power status of EPS was being decided by PID method according steering torque, speed, and other signals. Syetem agent coordinated control structute parameters and control parameters of SAS and EPS for adapt to different conditions.Finally, remended prototype passive damper, adjusted its damp by change orifice opening degree. Developed semi-accive damper of mini car and bench test it. Obtained characteristic curve and control relationship of damper. Then experimented on real vehicle road test, contrasted the experimentation results and simulation results.It was showed that the simulation results were coped with the experiments. MAS integrated controller operation is reliable, control strategy is effective and feasible. MAS harmonized the effect of suspension and steering subsystems preferably. In contrast with self-adaptive fuzzy integtated control, the body vertical acceleration and yaw rate were all reduced obviously. The center of mass acceleration, which characterized the ride performance, decreased peak in average 6.48%, and standard deviation decreased by 7.37%. The yaw rate, which characterized the handling stability, decreased peak in average 10.59%, and standard deviation decreased by 30.15%. The roll angle, which characterized vehicle body attitude, decreased peak in average 10.06%, and standard deviation decreased by 21.24%. The peak and standard deviation of handling torque of steering wheel were decreased by 18.10% and 30.38% respectively. From above on, MAS control results are more excellent than self-adaptive fuzzy control. Relieved conflict of vehicel ride comfort and handling stability. Driving safety was being more improved. This research provides an effective research method on integrated control of vehicel chassis large scale system.