【作者】 冯镇；

【导师】 马建；

【作者基本信息】 长安大学 ， 车辆工程， 2014， 博士

【摘要】 随着车辆行驶高速化的发展，车辆高速、大转角转向稳定性的问题越来越突出，且该问题在车辆动力学的研究中也越来越重要，而4轮转向技术可在很大程度上改善车辆高速、大转角转向的稳定特性。论文依托国家863计划现代交通技术领域重大项目增程/插电式重型商用车底盘开发（批准号：2012AA111106），以多电机驱动增程式环卫垃圾车辆为研究对象，研究多电机驱动增程式车辆的匹配方法；并从车辆非线性动力学模型、非线性动力学运动稳定性理论及非线性动力学结构稳定性理论3个不同的方面，对4电机驱动增程式车辆非线性转向动力学进行研究；通过建模仿真与非线性动力学理论研究，得到多电机驱动增程式车辆的匹配方法与4轮非线性转向的变化特性规律，为完善多电机驱动增程式车辆动力系统匹配研究及4轮转向技术在车辆上的应用提供了理论基础与研究依据。文章的主要工作如下：在传统动力匹配方法的理论基础上，提出多电机驱动增程式车辆的匹配原则与方法。以多电机驱动增程式环卫垃圾车辆为研究对象，基于传统车辆动力系统匹配理论，获得所研究车辆的初步动力匹配结果；根据传统匹配结果，研究驱动方式对所研究车辆动力匹配设计的影响，发现所研究车辆在多电机驱动时，其电机数目至少大于4个，否则车辆连启动都可能无法实现，并确定增程式环卫垃圾车辆由4个电机驱动；分别对驱动电机与增程发动机的工作效率区进行分析，获得多电机驱动增程式车辆运行协调的高效区，以改善所研究车辆的经济性。建立4电机驱动增程式车辆的高维纵侧向耦合非线性动力学模型，进行转向仿真研究，研究结果如下：由操稳性仿真揭示，模型跟随效果好，且可进行车辆操稳性控制策略的研究；通过车辆转向动力学仿真发现，车辆高速转向稳定性比低速转向稳定性差；无论车辆高速、低速行驶，随着前轮转角的增加，转向稳定性降低；进行4轮转向仿真发现，车辆低速转向时，车辆稳定性可以保证，应控制车辆后轮与前轮反向转向，有助于提高车辆低速转向灵活性；车辆高速转向的稳定性比低速转向时的稳定性差，当车辆高速转向时，应控制后轮与前轮同向转向，增加车辆高速转向的稳定性。基于非线性动力学运动稳定性理论，构造4电机驱动增程式车辆李雅普诺夫函数，对车辆非线性运动稳定性进行定性研究，发现车辆转向在初态邻域内李雅普诺夫意义下渐进稳定；从数学平衡点角度对所研究车辆的非线性运动稳定性进行定量研究，研究表明在初始状态的邻域内，车辆非线性转向渐进稳定；从数学平衡点角度分析前轮转角对车辆非线性转向的影响，发现随着前轮转角增加，车辆转向系统平衡点越容易失去，车辆转向稳定性降低；研究4轮转向对车辆非线性转向的影响，发现车辆高速运行，后轮与前轮反向转向时，车辆转向系统平衡点容易失去，车辆转向稳定性降低；后轮与前轮同向转向时，随着后轮转角的增加，所研究车辆的转向系统越不易达到平衡点失去状态，转向稳定性增加；基于以上研究还发现，低速转向系统的平衡点不易失去，车辆低速转向稳定性高。对4电机驱动增程式车辆进行非线性动力学结构稳定性研究，通过非线性动力学静态分岔与动态Hopf分岔理论，发现所研究车辆在4轮稳态转向时不发生Hopf分岔，但发生静态鞍结分岔；研究车速对车辆非线性稳态转向分岔的影响，发现随着车速增加，车辆越易达到分岔临界值，转向稳定性降低；研究前轮转角对车辆非线性稳态转向分岔影响，结果表明随着前轮转角的增加，车辆转向分岔的临界值减小，车辆转向的稳定性降低；研究后轮转角对车辆非线性稳态转向分岔影响，结果表明车辆高速行驶，当车辆后轮与前轮反向转向时，车辆转向分岔的临界值变小，车辆越容易发生不稳定转向，车辆转向的稳定性降低；当车辆后轮与前轮同向转向时，车辆转向分岔的临界值增加，车辆转向的稳定性增加；从非线性转向平衡域角度进行研究，发现当车辆前轮与后轮反向转向时，车辆转向的平衡域减小，车辆发生不稳定转向的可能性增加，车辆转向稳定性降低；当车辆前轮转角与后轮转角同向转向时，车辆转向的平衡域增加，车辆转向不易发生不稳定转向，车辆转向的稳定性提高；通过平衡域分析还发现，后轮转向对速度分岔值的影响与前轮转角大小有关，前轮转角越大，后轮转向对车辆非线性转向的影响越小。更多还原

【Abstract】 With the higher speed of the travelling vehicle, the more important for theproblem of the stability of the vehicle high speed and large angle steering, nd that isalso more serious in the study of vehicle dynamics, while the vehicle with four wheelsteering can largely improve the stability of the high speed and the large anglesteering. This paper based on the national863program major projects of moderntraffic technology’’ the extended-range/plug-in heavy commercial vehicle chassisdevelopment’’(Approval no.:2012AA111106), takes the extended-range sanitationgarbage vehicle with four-motor driving as the object, studies the matching method ofthe extended-range vehicle with multi-motor driving and the dynamics features of thefour wheel nonlinear steering vehicle from3different aspects, which are the vehiclenonlinear model, the motion stability and the structural stability of nonlinear dynamic.From the studies, gets the matching method of the extended-range vehicle withmulti-motor driving and the rules of four wheel steering, provides theoretical basisand the research gist for the study of dynamic system matching of the extended-rangevehicle with multi-motor driving and the application of four wheel steeringtechnology in vehicles. The main work is as follows:First the paper puts forward the power matching principles and methods of theextended-range vehicle with multi-motor driving based on the traditional powermatching method. Takes the extended-range sanitation garbage vehicle withmulti-motor driving as the object, gets the initial power matching results of theextended-range sanitation garbage vehicle with multi-motor driving base on thetraditional matching theory of the dynamic system; it researches the driving methodeffects on the power system matching of the studied vehicle, finds that when thestudied sanitation garbage vehicle drives by multi-motor the number of motor is noless than four, or the vehicle may not be able to realize the start; Then analyses theefficiency area of the driving motor and the range extender, obtains the high efficiencyarea which the extended-range vehicle with multi-motor driving works coordinated toameliorate the vehicle efficiency.Takes the extended-range heavy vehicle with four wheel driving as example,builds the nonlinear steering dynamic model with a multidimensional and thelongitudinal and lateral coupling, carries on steering simulation for the extended-rangevehicle with four-motor driving, obtains the results as follows: finds that the model is with good following effect and can be used to research the control strategy of thevehicle handling stability from handling performance simulation; From the vehiclesteering dynamics simulation knows that the steering stability of vehicle at a lowspeed is better than that at a high speed, regardless of the vehicle high speed and lowspeed, the steering stability becomes lower with the increasing angles. Then conductsthe four wheel steering simulation, when the vehicle steers at a low speed, controls therear wheel and the front wheel steering with reverse direction to advance the steeringflexibility because the steering stability is not the main influence factors now; whenthe vehicle steers at a high speed, controls the rear wheel and the front wheel steeringwith homodromous direction to enhance the steering stability because the vehiclestability at a high steering speed is worse than that at a low steering speed.Based on the movement stability theory of nonlinear dynamic, constructs theLyapunov function of the extended-range heavy vehicle with four-motor driving, doesthe qualitative research on the nonlinear movement stability of the extended-rangeheavy vehicle with four-motor driving, gets that the vehicle at the initial status isasymptotically stable in the sense of Lyapunov; conducts the mensurable research onthe vehicle nonlinear steering is asymptotically stable in the initial state of theneighborhood, which is in accord with the Lyapunov results. Studies the four wheelsteering effect on the equilibrium point of the vehicle nonlinear steering, and knowsthat when the vehicle steers with a high speed, the steering stability is depravationwith the rear wheel and the front wheel steering reversely; as the increasing of the rearwheel angle, when the rear wheel and the front wheel steering with homodromousdirection, the dynamic system of heavy vehicle can not easily reach the instabilitystate of the equilibrium point, the steering stability increases; Analyses the front wheelangle impacts on the equilibrium point of the vehicle steering dynamic system, withthe increasing of the front wheel angle, the vehicle steering stability reduces; And alsogets that the steering stability is not easy to the instability with a low steering speed.The conclusion is in conformity with the3rdchapter.Studies the structural stability of nonlinear dynamic, knows that the extended-range vehicle with four-motor driving does not occurs Hopf bifurcation but raises thestatic saddle-node bifurcation base on the nonlinear dynamic theory of the staticbifurcation and the dynamic Hopf bifurcation when steady steering; Analyses thevehicle speed effect on the bifurcation of the nonlinear steady steering vehicle, gets asthe vehicle speed increasing, the bifurcation critical value can be easily reached, the steering stability of the vehicle reduces; Studies the front wheel angle effect on thebifurcation of the nonlinear steady steering vehicle, knows that with the increasing ofthe front wheel angle, the bifurcation critical value of the vehicle steering decreases,the steering stability of the vehicle lowers; Analyses the rear wheel angle effect on thebifurcation of the nonlinear steady steering vehicle, gets the bifurcation critical valueof the vehicle steering becomes lessen when the rear wheel and the front wheelsteering with reverse direction, the steering instability can be easily attain and thesteering stability of the vehicle reduces. the bifurcation critical value of the vehiclesteering adds and the steering stability of the vehicle increases when the rear wheeland the front wheel steering with homodromous direction. Then from the balancedomain to analyses the nonlinear steering vehicle of the extended-range vehicle withfour-motor driving, gets that when the rear wheel and the front wheel steering withhomodromous direction, the balance domain of steering vehicle reduces, thepossibility of the equilibrium instability state raises when vehicle steering, it is easilyfor the steering vehicle to be instability; When the rear wheel and the front wheelsteering with reverse direction, the balance domain of steering vehicle raises, it is hardfor the steering vehicle to be instability and the stability improves; And the rear wheelsteering effect on the speed bifurcation relates to the size value of the front wheelangle, the greater the front wheel angle, the rear wheel steering has the smaller effecton vehicle nonlinear steering.更多还原