Simulation Research Onroll Stability Of Miniature Vehicle Based On Human-mechine Dynamic Coupling Theory

The electric vehicle has become a major trend in automobile development, whilethe miniaturization will become an important branch of electric vehicle. The miniatureelectric vehicle, with advantages of small size, light weight, simple structure, lowmanufacture costs, energy saving, envirement protection, and so on, will be an idealtransportation to alleviate the city congestion, environmental pollution and energy crisisin the future.With the miniaturization, some new problems about vehicle handling stability,which is closely related to driving safety, will be exposed.After miniaturization, thelongitudinal and horizontal dimensions of vehicle body have been greatly reducedcompared with tranditional vehicles, while the vertical dimension is quite to the latterdue to the requirement of passenger room.That may reduce the “stability margain” ofthe whole vehicle system, making the driving stability of miniature vehicle moreimpressionable to some external factors. Meanwhile, after reducing the curb weight ofminiature vehicle, the masses of passengers will occupy a large proportion in the wholevehicle. This may laed tostrongereffects of passenger’s mass and movement on thehandling stability. Therefore, the human-mechine dynamic coupling between hunmanand vehicle should and must be consideredwhile rearching the roll stability of miniaturevehicle.In order to research the influence of human-machine dynamic coupling on rollstability of miniature vehicle, the following tasks have been mainly carried out:①The mechanical mechanism of human-machine dynamic couoling has beendiscussed; and the simple mechanical coupling models, refering to the rolling of vehiclebody, have been founed; and the vibration modes of above coupling models have beencalculated and analyzed.②The virtual prototype model of a miniature electric vehicle has been establishedbased on mutibody dynamics theory and ADAMS/View software; the mutibody modelof human body, related to the vehicle roll stability, has been developed based on theprevious studies about human body dynamics;③The dynamic simulations of the whole vehicle, related to vehicle rollstability,have been designed and accomplished based on the theories and methods ofvehicle handling stability road tests; ④The differences of vehicle roll dynamic response, between before and afterconsidering human-machine dynamic coupling, have been analyzed comparatively; theimpacts of human-machine dynamic coupling on roll stability of miniature vehicle havebeen studied qualitatively and quantitatively; the influences of some external factors onthe effects of human-machine dynamic coupling have been explored.Through the simulations and analyses, this thesis has obtained the followingimportant cnclusionns:①After considering the human-machine dynamic coupling, there have been moremode orders and mode shapes as a result of the vehicle system owning more freedom,and the first order roll resonance frequency has reduced slightly.②After considering the human-machine dynamic coupling, there have beenlonger reaction time and stability time, higher steady velue and overshoot in rollresponse,under transient steering excitation; and there have been lower roll resonancefrequency, larger increased amptitude ratio, greater phase lag angle at low frequency orsmaller phase lag angle at high frequency, under continuous steering excitation.③The effects of human-machine dynamic coupling impacting roll stability arerelated to some external factors, such as human body mass, road adhesion coefficient.The greater the body mass is, or the lower the adhesion coefficient is, the more obviousthe impact of human-machine dynamic coupling on roll stabilitywill be.Therefore, the human-machine dynamic coupling should be considered whilereasearching the dynamics of miniature vehicle, and its handling stability and rollstability should be improved while designing the miniature vehicle.