【作者】 王前；

【导师】 丁康；

【作者基本信息】 华南理工大学 ， 车辆工程， 2013， 硕士

【摘要】 在Formula SAE的比赛中，要求赛车具备良好的侧向动力学稳定性，以尽可能高的速度过弯及避障。采用基于线性轮胎力的经典二自由度车辆模型无法对赛车在极限状态下表现出的非线性特性进行分析，因此需要引入非线性轮胎力以及车辆的侧倾运动，在非线性域内对FSAE赛车的侧向动力学稳定性进行研究。论文主要进行了以下几方面的工作：(1)在经典二自由度车辆模型的基础上建立了考虑侧倾运动的三自由度四轮车辆侧向动力学模型。通过对比该模型与经典二自由度车辆模型与不考虑侧倾运动的四轮二自由度车辆模型的相平面与系统平衡点分岔图，证明了侧倾运动会导致车辆在相平面上的稳定区域减小，因此车辆更容易失稳。(2)采用多种方法对FSAE赛车车辆参数进行识别。提出了一种新的自适应差分进化参数识别方法对MF2002轮胎模型参数进行识别，该方法有助于提高识别的精度与效率。结合实验和计算分别确定了赛车悬上部分、悬下部分以及车手的惯性参数，并整合得到包含车手在内的FSAE赛车整车惯性参数。(3)作出了基于MF2002轮胎模型的三自由度四轮FSAE赛车模型的侧向动力学相平面图与平衡点分岔图，确定了赛车在不同输入下的稳定状态。发现相平面上出现两个新的不稳定平衡点，分析其原因是极限状态下轮胎侧偏刚度减小至零并出现负增长导致系统特征方程系数p<0。还使用该模型对FSAE动态比赛8字绕环的项目进行了仿真计算，得到了不同车速下车辆作稳态的定半径转向的极限性能，并确定了前10psi（68.94kpa）后8psi（55.15kpa）配置下的赛车具备最佳的侧向动力学稳定性，该配置下赛车作8字绕环单圈的时间相比原来减少了5.7%，其侧向极限性能得到了一定的提升。(4)实验测试表明，在一定前轮转角与车速下赛车作圆周运动的状态参数响应测试曲线与仿真得到的响应曲线较相符，证明了文中建立的车辆模型的正确性。更多还原

【Abstract】 The FSAE Racecar is required to have good lateral dynamic stability to turn a corner oravoid an obstacle as quickly as possible. Under these extreme conditions, the car showsnonlinear characteristics that can’t be analyzed using the classic2-wheel-2-DOF vehiclemodel based on the linear tire force. Therefore, the nonlinear tire force and roll motionshould be introduced to study the lateral dynamic stability of FSAE Racecar in thenon-linear domain. The thesis mainly consists of the following parts:(1) The4-wheel-3-DOF vehicle lateral dynamic model including roll motion isestablished based on the classic2-wheel-2-DOF vehicle model. By comparing the phaseplane portrait and the equilibrium-point bifurcation diagram of the new model with theclassic2-wheel-2-DOF and4-wheel-2-DOF vehicle model，it has been demonstrated thatthe roll motion would lead to the decrease of the stable region on the phase plane, whichmeans the car is more easy to be destabilized.(2) The parameters of the FSAE Racecar are identified through multiple methods. Anew self-adaptable differential evolution algorithm is presented to identify the parameters ofMagic Formula2002tire model, which helps to improve the accuracy and efficiency of theidentification. Besides, the inertial parameters of the suspended part, the unsuspended partof the racecar and the driver are determined through the combination of experiments andcalculation. And to get the whole inertial parameters of the racecar (including the driver),the three parts of parameters are integrated.(3) The lateral dynamic phase plane portrait and the equilibrium-point bifurcationdiagram of the4-wheel-3-DOF FSAE racecar model are plotted to determine the steadystate of the racecar under different inputs. The results show two new equilibrium points onthe phase plane, and the reason for their existence is that the parameter of the systemcharacteristic equation, p, is less than zero, and this is caused by the tire cornering stiffnessthat decrease to zero or negative value under extreme conditions. The model is also used tosimulate one of the dynamic events, the skid-pad, to find the extreme performance of the racecar while it is doing steady circling motion at constant radius. And the racecar withfront tires of10psi (68.94kpa) and rear tires of8psi (55.15kpa) is proved to have the bestlateral dynamic stability. This tire pressure setting make its lap times reduce by5.7%comparing to the original setting and improve the lateral extreme performance.(4) The result of the real test shows that the response curve of the motion-stateparameters from the test is consistent with the curve from the simulation while the racecar isdoing circling motion under a certain input of front-wheel-turning angle and vehiclevelocity, which demonstrates the correctness of the newly-established vehicle model.更多还原