【作者】 陈利；

【导师】 汪洪波； 谢有浩；

【作者基本信息】 合肥工业大学 ， 交通运输工程（专业学位）， 2019， 硕士

【摘要】 随着汽车技术的迅猛发展,车道保持辅助系统在汽车主动安全技术领域扮演着越来越关键的角色,作为智能汽车高级驾驶辅助系统核心技术之一,用于汽车当检测到有发生车道偏离的危险时,控制汽车回到道路中心线,或减少因驾驶员疏忽及疲劳驾驶导致车道偏离而引发的交通事故。在车道保持辅助系统中,横向控制器设计的好坏对车道保持的控制效果起到至关重要的作用,好的控制策略和路径跟踪方法可以达到实时高效、可靠安全的车道保持效果。本文首先基于人工势场法对车道保持进行横向控制器设计,在考虑汽车行驶速度对势场函数影响的基础上,同时考虑汽车行驶安全性和操纵稳定性,从而引入横摆角变化速率调节因子以调节势场函数,并采用可拓决策对速度影响因子和横摆角变化速率调节因子在势场函数中所占比重进行分配,最后基于二自由度汽车动力学模型进行滑模控制器设计,获得期望前轮转角。同时,为解决车道保持过程中,系统频繁启动造成的不稳定问题,对车道保持的侧向距离偏差和角度偏差的动态阈值进行模糊决策,当其中任何一个的实际值大于其阈值时,系统启动;当二者的实际值皆小于其阈值时,系统关闭。其次,将横摆角速度和质心侧偏角作为判定汽车稳定性的特征量,并划分汽车行驶的安全边界,然后基于此边界,建立平面直角坐标系,将汽车的运动状态划分为稳定状态、稳定到不稳定的过渡状态以及不稳定状态,根据汽车行驶的状态参数判定主动前轮转向和直接横摆力矩的控制权重,并分别设计控制器,实现二者的协调控制。最后,为了验证加入横摆角变化调节因子后的改进人工势场所设计的可拓滑模控制器相较于仅仅考虑速度影响因子的改进人工势场的有效性,以及主动前轮转向/直接横摆力矩协调控制相较于采用单独转向控制的优越性,进行了Carsim/Simulink联合仿真;同时,为了进一步验证所设计横向控制器能够在一定程度上提升车道保持系统的总体性能,借助实验室已有条件和设备,进行PXI实时硬件在环台架试验。结果表明,所设计的车道保持横向控制器和主动转向/横摆力矩协调控制策略不仅能够达到良好的车道保持效果,同时还提升了系统的稳定性。更多还原

【Abstract】 With the rapid development of vehicle technology,Lane Keeping Assistance System(LKAS)plays a more and more critical role in the field of active safety technology.As one of the core technologies of advanced driving assistance system for intelligent vehicles,LKAS is used to control the vehicle to return to the central line of the road when the danger of lane deviation is detected,or to reduce the lane deviation caused by driver’s negligence and fatigue driving.In LKAS,the design of lateral controller plays a vital role in the control effect of lane keeping.Good control strategy and path tracking method can achieve real-time,efficient,reliable and safe lane-keeping effect.In this paper,a lateral controller for lanekeeping is designed based on the artificial potential field method firstly.Considering the influence of vehicle speed on the potential field function,also considering vehicle driving safety and handing stability,the yaw angle change rate adjustment factor is introduced to adjust potential field function.And the proportion of speed influence factor and yaw angle change rate adjustment factors in potential field function is allocated by extension decision.The sliding mode controller is designed for the DOF vehicle dynamics model to obtain the front wheel rotation angle.At the same time,in order to solve the problem of system instability caused by frequently starting up the lane-keeping system,the dynamic threshold of lane-keeping distance deviation and angle deviation is made a fuzzy decision.When the real value of any one of them is greater than its threshold,the system starts;when the real value of both is less than its threshold,the system closes.Secondly,the yaw rate and sideslip angle of the center of mass are taken as the characteristic variables to determine the stability of the vehicle.And the safety boundary of the vehicle is divided.Based on this boundary,a plane rectangular coordinate system is established.The motion state of the vehicle is divided into stable state,transition state from stable to unstable and unstable state.The control weights of active front wheel steering and direct yaw moment are determined according to the driving state parameters of the vehicle.And the controllers are designed separately to realize the coordinated control of the two.Finally,in order to verify the validity of the extended sliding mode controller with yaw angle adjusting factor compared with the improved artificial potential field with only considering the velocity influence factor,and the superiority of the active front wheel steering/direct yaw moment coordinated control over the single steering control,Carsim/Simulink joint simulation is carried out.The transverse controller designed by the stock exchange can improve the overall performance of the lane-keeping system to a certain extent.With the help of the existing laboratory conditions and equipment,the PXI real-time hardware in the loop test is carried out.The results show that the designed lanekeeping lateral controller and active steering/yaw moment coordinated control strategy can not only achieve good lane-keeping effect,but also improve the stability of the system.更多还原