【作者】 聂佳梅；

【导师】 陈龙； 江浩斌；

【作者基本信息】 江苏大学 ， 载运工具运用工程， 2009， 博士

【摘要】 悬架和转向系统是汽车的两个重要组成部分,与汽车的行驶平顺性和操纵稳定性等诸多性能有关。随着电子控制技术及单片机技术的发展,汽车半主动悬架(Semi-Active Suspension,SAS)和电动助力转向(Electric Power Steering,EPS)成为研究的热点。SAS可在一定程度上同时改善汽车的操纵稳定性和行驶平顺性,EPS可提高操纵稳定性和转向轻便性。但由于悬架系统与转向系统之间存在一定的耦合作用,针对单一系统进行控制时,只能改善车辆的局部性能,而整车的综合性能很难得到较大幅度的提高。要获得更优的整车综合性能,需要对这两个系统进行集成控制。本文以提高车辆的操纵稳定性和行驶平顺性为目标,对车辆SAS与EPS系统的协调和集成控制作了较系统的研究。针对转向与悬架两子系统间的相互约束和影响,改进了SAS与EPS集成系统整车动力学模型,在轮胎模型中考虑了轮胎垂直载荷变化对轮胎侧偏特性的影响,转向子模型受力分析中考虑到轮胎侧偏力的实际方向,使模型更接近于实际情况。在仿真分析的基础上,研究了悬架系统与转向系统之间的耦合关系。针对集成控制的两个目标:消除子系统间的不利干扰和冲突、合理分配各子系统的控制输入,提出了SAS与EPS系统分层协调控制方法,并设计了协调控制器。分别建立了SAS子系统模糊控制器和EPS子系统PID控制器,以车辆的整体性能最优为目标,构建上层控制的协调策略。仿真结果表明,分层协调控制可有效提高汽车的综合性能,协调汽车的行驶平顺性和操纵稳定性。分层协调控制策略是研究集成控制的有效方法。针对SAS与EPS系统多输入多输出的特点,基于灰色预测理论,建立了SAS与EPS系统性能指标的多变量灰色预测模型,实现性能指标的预测,预知系统性能指标的发展趋势。根据预测值对集成控制策略进行预先修正,以实现SAS与EPS系统的事先控制,避免了控制变量的大幅度急剧调整,使控制效果更精确。在此基础上,提出了基于灰色预测的SAS与EPS集成系统分层协调控制方法,并设计了灰色预测协调控制策略,减少了不确定因素的影响和控制系统时间滞后引起的控制不精确,大幅度改善了执行机构的控制性能。采用灰色预测控制,有效改善了SAS与EPS系统的集成控制效果。仿真结果表明这种控制方法完全可以满足SAS与EPS系统的集成控制需要。研究开发了基于ARM2131的SAS与EPS系统集成控制器硬件。将改进的半主动悬架和开发的集成控制器装在北斗星CH7140轿车上进行实车道路试验,并将试验结果与仿真结果进行对比。仿真试验结果和实车试验结果基本吻合,表明所建立的集成系统模型正确,控制策略可行,技术可靠,为汽车底盘系统的集成控制研究提供了良好的技术基础。灰色预测分层协调控制的系统与被动系统相比,质心垂直加速度的峰值下降28.57%,标准差下降27.75%;横摆角速度的峰值下降10.18%,标准差下降12.69%;车身侧倾角峰值下降15.8%,标准差下降8.19%;侧向加速度峰值下降20.8%,标准差下降18.6%;在人体敏感频率区域内,质心加速度功率普密度也有明显的降低。表明灰色预测协调控制能够较好的协调汽车行驶平顺性和操纵稳定性之间的矛盾,使整车综合性能得到提高。更多还原

【Abstract】 Suspension and steering system are two important components of the vehicle,and their performance is directly related to vehicle’s performances such as ride comfort and handling stability.As the development of the electronic control technology and single chip technology,vehicle’s semi-active suspension(SAS) and electric power steering(EPS) have become a research hotspot.SAS can,to a certain extent,improve the handling stability as well as the ride comfort,while EPS can improve the handling stability and steering portability.However,due to the coupling effects between the suspension system and the steering system,when the systems are controlled respectively,only partial performance is improved, while the comprehensive performance of the vehicle is quite hard to be enhanced in large scales.In order to acquire a better comprehensive performance,the two systems should be controlled integratedly.In this paper,aiming at the improvement of vehicle’s handling stability and ride comfort,a systematic research on coordination and integrated control of SAS and EPS is undertaken.In view of the mutual restraints and impact between the two systems, the full vehicle dynamic model with integrated system of SAS and EPS is improved.In the tyre model,the effects from changeable vertical load to tyre cornering characteristics is taken into consideration,so is the actual direction of tyre cornering force in the steering model.As a result,the whole model is much closer to the real vehicle.Based on the simulation and analysis of the above models,the coupling relation between the suspension system and steering system is studied.In respect of the two goals of the integrated control:to eliminate the harmful interference and conflicts between the systems and to assign the control inputs of the subsystems reasonably,a layered coordination control method is proposed,and a coordination controller is designed,and a fuzzy controller of SAS and a PID controller of EPS is made respectively.Then aiming at the optimization of the whole vehicle,the coordination strategy of the upper control is established.The results of the simulation show that, the layered coordination control can,improve vehicle’s comprehensive performance effectively,and coordinate the ride comfort and handling stability.The layered coordination method is proved to be an effective way in studying integrated control.For the multi input multi output characteristics of SAS and EPS system, and based on grey predictive theory,a multi-variable grey prediction model of SAS and EPS system is established,to predict the performance indexes and their developing trend.Then according to the prediction,the integrated control strategy is in advanced revised,to realize the pre-control of the SAS and EPS system by avoiding a rapid change of the control variables,thus the control is more precise.On the above basis,a layered coordination control method on SAS and EPS integrated system,based on grey predictive theory,is proposed,and a grey predictive coordination control strategy designed.As a result,control imprecision caused by uncertain factors and time delay of the control system is eliminated,and the control performance of the executing agency improved in a large scale.The integrated control effect of the integration system,by adopting grey predictive control,is improved efficiently.As shown in the results of the simulation,this control method can completely meet the need of the integrated control of SAS and EPS integrated system.Integrated system of SAS and EPS controller is explored with ARM2131 single chip computer as microprocessor.The improved semi-active suspension and the integrated controller are installed in the CH7140 to carry on the real vehicle road tests,and the results will be compared with the simulation results.It is showed that the simulation results are coped with the experiments and it is indicated that the established model is right,the control strategy feasible and the technology reliable.In contrast with the passive system,the peak and the standard deviation of the center of mass acceleration is decreased by 28.57%, 27.75%;the yaw rate’s peak and standard deviation is decreased by 10.18%, 12.69%;the roll angle’s peak and standard deviation is decreased by 15.8%, 8.19%;the lateral acceleration’s peak and standard deviation is decreased by 20.8%,18.6%.In human sensitive frequency range,the power spectrum of the center of mass acceleration is reduced obviously.It is showed that the grey predictive layered coordination control can coordinate the contradiction of vehicle ride comfort and handling stability and improve the vehicle performance.更多还原