Simulation Analysis Of Steering Wheel Angle Step Input Vehicle Handling And Stability

At present, as the vehicle speed becomes higher and higher, the freight flow more andmore crowded and the drivers are more unprofessional, there are more and more trafficaccidents. The safety problem of road traffic is widely concerned by the society. According totheir proportions, arrange the evocable factors of accidents from bigger to smaller, and theresult is as follows: handling stability, acceleration and brake performance, environmentvisibility, reliability. Therefore, handling stability is called as "the lifeline of vehicle at a highspeed", and is one of the important performances of modern vehicles.As to studies on vehicle handling stability, there are two ways: simulation analysis and testanalysis. Simulation analysis is creating a simple digital model of complete vehicle oncomputers, inputting all kinds of handling signals, and calculating the temporal and frequencyrespond of the system which signifies the vehicle handling stability. The simulation analysiscosts short time, can be done repeatedly to contrast and optimize all kinds of design projectsquickly and can run in the severe working condition where the test analysis can't run.Therefore, the simulation analysis is being used increasingly.Handling stability concerns comprehensive problems and needs to be evaluated by manyparameters from different ways. Nowadays, because of the influence of many factors such asresearch aims, driving task, artificial feelings and the environment, the research and evaluationof handling stability is complex. In the text, perform the most representative evaluation test:step angle input of steering wheel. The instant respond of step angle input of steering wheel isused to signify vehicle handling stability, analyze and evaluate the basic parameters of handlingstability to improve it and provide the optimum result before producing actual prototypes.The text is based on multi-body system dynamics, create the dynamic simulation model ofMPV complete vehicle including front and rear suspensions, steering system, tires, engine, carbody with MSC.ADAMS/car. Then perform the simulation analysis on the dynamic models offront and rear suspensions, calculate their stiffness curves and wheel alignment parametercurves and validate the models according to given data. The models accord with requirementsby validation.The text also performs step angle input simulation test of steering wheel on the dynamicsimulation model of complete vehicle according to GB/T 6323.2-1994 and get the vehiclemotion state – the response of yaw velocity, lateral acceleration and car body roll angle and soon. Compare the test result and the simulation result of the response time of yaw velocity totestify whether the simulation model is correct or not. Then grade the test result according toQC/T 480—1999 . Theevaluation value of the yaw angular velocity of MPV N J=88.57, which proves that thehandling stability of MPV is good.Finally, perform step angle input simulation test of steering wheel under different vehiclespeeds, different step input speed and different loads. From the simulation analysis, we can getyaw angular velocity and lateral acceleration respond curves and analyze in detail severalcommon evaluation targets of handling stability. The conclusions are as follows: thesteady-state steering characteristic of MPV under all loads is under-steer. The vehicle speed hascertain influence on the steering behavior. Along with vehicle speed increasing, the yawangular velocity and lateral acceleration fluctuate bigger and bigger and the respond time of theyaw angular velocity becomes smaller and smaller. Stability factor varies in a small range andother parameters vary a lot. When vehicle is under-steer, yaw angular velocity will arrive atmaximum under a certain speed. The angle input speed has little influence on the steeringbehavior. The respond time and peak respond time of yaw angular velocity becomes smallerand other parameters don't change. Load has little influence on the steering behavior. Alongwith load increasing, the steady-state value and peak value of yaw angular velocity and lateralacceleration increase weakly.