【作者】 刘健；

【导师】 梁忠超；

【作者基本信息】 东北大学 ， 机械工程（专业学位）， 2022， 硕士

【摘要】 现如今,传统燃油汽车的污染问题已经成为汽车行业发展不可避免的问题。分布式驱动电动汽车通过4个轮毂电机分别对4个车轮实现独立控制,具有响应迅速、控制方便等优势,是未来汽车行业发展的重要研究方向之一。但是,电动汽车驱动系统作为一种过驱动系统,当工作条件恶劣时有极大的可能使车辆驱动失效,不仅会降低车辆的操纵性能,而且由于两侧驱动力不等产生的附加横摆力矩容易导致车辆横摆失稳。并且由于执行器存在物理极限,可能使控制输入发生饱和,当输入发生饱和时也会严重影响车辆的操纵稳定性。因此本文在考虑局部车轮驱动失效和地面附着力饱和的情况下对四轮驱动电动汽车的操纵稳定性控制进行了研究。考虑到车辆局部车轮驱动失效时,本文提出了一种应用于电动汽车的基于滑模控制的被动容错控制方法。当车辆行驶在极限路面条件下,驱动电机可能会发生故障,使得车轮的驱动力矩突然下降。由于在故障诊断机构工作完成前,驱动电机的故障信息未知,采用容错控制方法不需要知道发生故障时驱动力矩的大小,可以极大程度的维持车辆稳定性,容错控制器的控制目标是使每个状态变量追踪它的期望值,从而保证车辆的行驶稳定性。本文将具有相同作用的控制器分组,在设计控制器之前建立力矩成本函数将输入力矩进行分配,最后设计基于滑模控制策略的被动容错控制器。考虑到控制输入饱和时,本文提出了一种应用于电动汽车的预防输入饱和的自适应积分终端滑模控制方法。当车辆在粗糙路面上高速转向运动时,车辆可能会发生滑移和甩尾现象。并且此时车辆的侧偏角过大,极大的降低了车辆的乘坐舒适性,严重时车辆可能发生侧翻,因此本文通过控制轮胎力和主动悬架力矩来保证车辆横摆运动以及侧倾运动的稳定性。由于受到轮胎地面条件和物理条件的限制,控制输入存在饱和,这不仅会限制控制器的控制性能,同时如果控制输入超过饱和界限,会对相应的执行器产生伤害。为了避免控制器发生饱和,引入了控制输入饱和系数,提出了一种自适应积分终端滑模控制器,当输入超过饱和值时能够自动地调整控制输入使其避免饱和。当考虑到地面附着力饱和和执行器故障的复杂工况时,本文设计了一种控制切换策略,通过给定判断方法来切换不同的控制器以保证车辆在不同工况下的稳定运行。并且在执行器故障和地面附着力饱和的情况下,设计了一种主动诊断模块,结合主动诊断模块和被动容错控制器来保证车辆的行驶稳定性。通过主动诊断模块对故障车轮进行定位,并对故障一侧车轮附加相应的增益来减小故障轮的控制输入,避免故障车轮的进一步损坏。更多还原

【Abstract】 Nowadays,the pollution problem of traditional fuel-fired vehicles has become an inevitable problem for the development of the automobile industry.Distributed driven electric vehicles realize independent control of four wheels through four hub motors respectively,with the advantages of rapid response and convenient control,which is one of the important research directions for the future development of the automobile industry.However,as an overdriving system,an electric vehicle driving system may greatly fail the vehicle drive when the working conditions are bad,which will not only reduce the handling performance of the vehicle,but also easily lead to yaw instability due to the additional yaw moment caused by the unequal driving forces on both sides.And due to the physical limit of the actuator,the road adhesion may be saturated.When input saturation occurs,it will also seriously affect the handling stability of vehicles.Therefore,the operating stability control of four-wheel drive electric vehicles is studied while considering the local wheel drive failure and the control input saturation.This paper presents a passive fault-tolerant controller based on sliding mode strategy for a four-wheel-independently-actuated electric vehicle considering the local wheel drive failure.When a vehicle is running on extreme road conditions,the drive motor may fail,causing the drive torque of the wheels to suddenly drop.As the driving motor fault information is unknown without the fault detection and diagnose procedure.The value of driving torque on failed actuators for passive fault tolerant control is not required,and this method can greatly maintain vehicle stability.The control objective of a fault-tolerant control is to make each output signal track its expected value.In this paper,the actuators are grouped into the same group with the same function and distributed appropriate input torques by establishing a torque cost function.Finally,a passive fault-tolerant controller based on sliding mode control strategy is designed.The paper proposes an adaptive integral terminal sliding mode control method for electric vehicles considering input saturation.When the vehicle is steering at high speed on rough roads,the vehicle may slip and drift,and the lateral Angle of the vehicle is too large,which greatly reduces the ride comfort of the vehicle.In serious cases,the vehicle may roll over.Therefore,this paper realizes the control of the yaw and roll motion of the vehicle by controlling the tire force and active suspension torque.At the same time,the control inputs are saturated due to the limitation of tire-road conditions and physical conditions,which will not only limit the control performance of the controller,but also damage to the corresponding actuators.In order to avoid saturation of the controller,the saturation coefficients of control input are introduced,and an adaptive integral terminal sliding mode controller is proposed.When the control input exceeds the saturation value,it can automatically adjust the control input to make it unsaturated.When considering the complex working conditions of control input saturation and actuator failure,a control switching strategy is designed in this paper,which different controllers are switched by a given judgment method to ensure the stable operation of the vehicle under different working conditions.Considering that the control input is saturated and the actuators are at the same time,an active diagnosis module is designed,which combines the active diagnosis module and the passive fault-tolerant controller to ensure the driving stability of the vehicle.The faulty wheel is located by the active diagnosis module,and the corresponding gain is added to the wheel on the faulty side to reduce the control input of the faulty wheel and avoid further damage to the faulty wheel.更多还原