【作者】 高新朝；

【导师】 初亮；

【作者基本信息】 吉林大学 ， 车辆工程， 2012， 硕士

【摘要】 主动前轮转向系统（Active Front Steering）与电子稳定性系统（Electronic StabilityControl）都能够改善车辆稳定性。由于AFS和ESC存在特性差异，因此在控制过程中必然存在干涉。为了解决此问题，充分发挥AFS和ESC各自的优势，更好的改善车辆的稳定性，需要对AFS和ESC进行协调控制。目前国内对电子系统的协调控制研究大多采用的集成度较低的分散式结构，此种结构的集成控制在改善车辆性能方面的效果不明显，国外采用的是集成度较高的集成式结构，集成式结构过于复杂，整合能力低。即使有些研究采用了分层控制，但是很少针对车辆状态的不同进行动态的协调控制。本文主要对AFS和ESC的协调控制策略进行了研究。具体内容如下：1）主动前轮转向系统与电子稳定性系统的特性分析分析AFS和ESC的结构和原理。对AFS和ESC的有效工作区域以及AFS、ESC对车辆稳定性的影响进行分析。为协调控制策略的研究奠定了理论基础。2）车辆稳定域的划分依据相平面的非稳定平衡点能够对车辆稳定域边界定量描述的特性，在相平面基础上划分稳定域。由于相平面的动力学方程是关于前轮转角、车速、路面附着系数的方程，所以稳定域随着上述三个因素的变化而不同。本文将车辆状态根据上述三个因素的不同划分为18种情况，将车辆当时的状态对应某种情况，采用遗传算法确定其非稳定平衡点，最终得到车辆的稳定域边界。3）主动前轮转向系统和电子稳定性系统协调控制区域的划分向内和向外偏移稳定域边界可以得到协调控制区域。由于控制区域边界受车速和前轮转角的影响，所以应用鲁棒性较好的模糊控制理论，以车速和前轮转角为输入，以表征偏移量的控制系数为输出对协调控制区域进行划分。4）确定目标横摆力矩滑模控制理论对系统参数外干扰及摄动具有很好的鲁棒性，适合稳定性控制，本文采用滑模控制理论计算保持车辆稳定的目标横摆力矩。5）对目标横摆力矩进行分配车辆在不同状态区域时，AFS和ESC承担的工作负荷不同，根据1）确定的车辆协调控制区域的划分原则，确定车辆当时所处的区域，对AFS和ESC的工作负荷进行合理的分配。为了验证AFS与ESC协调控制策略的有效性和优越性，在MATLAB/SIMULINK环境下搭建协调控制离线仿真平台，并在该平台下进行多种典型工况的离线仿真。结果表明：本文提出的AFS与ESC的协调控制策略进一步提高了车辆的稳定性。本文的创新点如下：1）考虑了车速、前轮转角、路面附着系数对车辆稳定域的影响，将上述三个因素引入到AFS与ESC协调控制中，进一步提高了协调控制的效果。2）应用遗传优化算法求解划分车辆稳定域的非稳定平衡点，解决了该非线性系统无法求解的问题。3）考虑了车速、前轮转角对协调控制区域划分的影响，采用鲁棒性较好的模糊控制动态地划分了协调控制区域，进一步提高了车辆的稳定性。更多还原

【Abstract】 Both AFS and ESC have an important role in improving the stability of the vehicle.But there are differences in characteristic of AFS and ESC, so there is interference in theprocess of control. To resolve this question, and make best of the advantage of AFS andESC to further improve the stability of the vehicle.At present, the distributed structurewhich is low in integration is mostly used to study the coordination control of electronicsystem at home,this kind of control have little effect in improving the performance of thevehicle. The integrated structure which is high in integration is mostly used to study thecoordination control of electronic system at abroad, this kind of control is too complex andconformity ability is low, even if hierarchical structure is used in some studies, few studiesuse the dynamic control according to the state of the vehicle. the paper study on thecoordination control strategy.The main contents are as follows:1) Analysis of the characteristics of AFS and ESCThe structure, the principle, the effect on the stability of AFS and ESC and theeffective area that AFS and ESC work are analyzed to lay a theoretical foundation for thestrategy of coordination control of AFS and ESC.2) The division of the stability regionDue to the stability domain boundaries can be described by the non-stable equilibriumpoint of the phase plane quantitatively. The control region is divided based on the phaseplane. The stability region is different with the change of front wheel angle, vehicle speed,and road adhesion coefficient, since the kinetic equation of the phase plane is the equationof front wheel angle, vehicle speed, and road adhesion coefficient. The vehicle condition isdivided into eighteen kinds of conditions, the state of the vehicle can be cooresponded to atypical condition and the genetic algorithms is used to determine its non-stable equilibriumpoints which determine the stability region boundary.3) The division of the coordination control area of AFS and ESCThe stability region boundary is translated inward and outward to get the coordinationcontrol area. the coordination control area is affected by the vehicle speed and the front wheel angle, so the Fuzzy control which has good robustness is applied, and the vehiclespeed and the front wheel angle are made as the inputs, and the control coefficients whichdetermine the offset are made as outputs to divide the coordination control area.4) The determine of the target yaw momentSince the sliding mode control theory has good robustness on system parameters andoutside interference, so the sliding mode control theory is applied to get the target yawmoment.5) The distribution of the target yaw momentThe workload of AFS and ESC is different when the state of the vehicle is different.The area which the vehicle locates is determined based on the principle of division of theregion to distribute the workload of AFS and ESC.In order to validate the validity and advantage of the coordinated control strategy ofAFS and ESC, simulation platform on which the off-line simulation is carried out is built inMATLAB/SIMULINK environment. The simulation results show that this control strategyimproved the stability of the vehicle effectively.The innovation of this paper is as follows:1) The speed, the front wheel angle and the road friction coefficient are made as theinfluencing factor to recognize the dynamic coordination control stable region to enhancethe effect of the coordinated control.2) The genetic optimization algorithm is applied to resolve the nonlinear system.3）The speed and the front wheel angle which effect the division of the coordinationcontrol region are considered, The Fuzzy control which has good robustness is applied todivide the coordination control region to enhance the effect of the coordinated control.更多还原