电动轮汽车差速助力转向路感分析

电动轮汽车为汽车转向技术提供了一种新的方法,它运用了差速助力转向系统,在可以实现转向灵敏和转向路感的完美结合的同时,有效降低了汽车转向系统的能耗,解决了转向系统机械结构复杂的问题,提高了汽车行驶的安全性,是一种比较理想的汽车动力转向技术。文中采用拉格朗日方法建立考虑车身侧倾的3自由度汽车转向系统模型,并对差动助力转向系统进行转向路感分析,通过在Matlab中建立模型进行仿真,研究各个参数对路感的影响,得出了影响路感的参数。     

基于dSPACE的EPS系统ECU硬件在环实验台设计与应用

硬件在环仿真测试是ECU研发过程中重要一环,对其性能调试起着关键作用。文章重点阐述基于dSPACE的EPS(电动助力转向)系统ECU(电控单元)硬件在环仿真试验台的设计与应用。基于dSPACE硬件在环仿真器,构建了EPS ECU的硬件在环仿真试验台。通过整合dSPACE系统内部车辆动力学仿真模型与改进的转向系统模型,获得更为接近实车的汽车动力学仿真模型。基于所设计的试验台,对某开发的EPS ECU进行离线测试并分析其性能表现。结果表明,该ECU能较好地满足汽车对转向轻便性、路感及回正性能的要求。     

基于摄像头识别汽车随动辅助大灯的模糊控制策略

文章提出了一种基于摄像头识别的汽车随动辅助大灯的模糊控制策略。通过摄像头和图像处理对驾驶人驾驶姿态进行采集和分析,并根据这些数据针对驾驶人以及车辆,设计了一种对汽车随动辅助大灯的模糊控制策略,包括大灯左右转向和俯仰转向的控制策略。模糊控制综合考虑驾驶员的驾驶倾向和可能遇到的道路情况,实现辅助车灯的随动转向。仿真实验验证了所提控制策略的有效性。     

电子机械式制动执行器硬件在环仿真

电子机械制动技术是一种全新的制动理念,极大的提高了汽车的制动安全性.文中介绍了电子机械制动系统的发展、组成及工作原理;搭建了电子机械式制动执行器原理机硬件在环仿真试验平台.以1/4车辆模型为研究对象,对基于模糊控制方法的车辆防抱死制动特性的Matlab/Simulink仿真结果和硬件在环仿真结果进行比较分析.验证了电子机械式制动执行器的合理性和可行性.     

四轮独立驱动电动汽车EPS转向特性研究

为更好地研究EPS对四轮独立驱动电动汽车转向特性的影响,运用Matlab/Simulink、Carsim建立了EPS联合仿真模型。提出基本助力控制、回正控制、阻尼控制、补偿控制策略,然后进行硬件在环试验确定其策略的有效性。试验表明:EPS控制下的四轮独立驱动电动汽车在低速行驶时使转向更加轻便;高速行驶时有更好的"路感"并提高了车辆的稳定性,从而整体改善汽车驾驶的操纵性能。     

汽车动力转向系统可变助力特性的设计

通过理论分析、数值仿真和经验统计等方法,对可变助力转向系统的助力特性进行研究,提出一种基于驾驶员路感的可变助力转向特性设计方法,并对其进行整车仿真试验.结果表明:所得到的可变助力特性,不仅能满足低速行驶转向时的轻便性要求,而且可保证在高速行驶转向时有合适的路感和必要的稳定感.     

基于模糊控制的车辆动力学稳定性控制研究

运用模糊控制原理设计了汽车横摆角速度和质心侧偏角联合反馈控制的模糊控制器,使汽车实际的横摆角速度和质心侧偏角与名义值的差值保持在一定的稳定范围,保证汽车的稳定性,并使用Matlab/Simulink软件对这一控制模型进行仿真,验证控制算法的有效性;以dSPASE软件为基础,设计了车辆动力学稳定性控制硬件在环模拟试验平台...     

转向路感控制系统在汽车上的应用

本文介绍一种汽车电液主动转向路感控制系统,提出一种控制策略,通过估算车辆状态信息,分别在执行或不执行主动转向干预时,进行路感控制,保证行驶稳定性。     

汽车前轮电子转向控制算法研究

本文建立了为驾驶员提供路感的电子转向系统转向盘回正力矩模型,研究了降低驾驶员负担、提高汽车稳定性的前轮电子转向控制算法,并利用开发型汽车驾驶模拟器进行仿真试验和验证,为电子转向系统的进一步研究和开发奠定了理论基础.     

商用车电液复合转向系统的车道保持策略

为了提高商用车的行驶安全性,避免因驾驶人的分心驾驶出现车辆偏离车道的问题,提出一种基于电液复合转向系统的商用车车道保持策略;在建立电液复合转向系统模型、二自由度车辆模型、预瞄驾驶人模型的基础上,设计基于驾驶人在环的MPC和ADRC串级的车道保持控制策略。首先,采用MPC算法将车辆横向位置控制的最优问题转化为二次规划求得目标前轮转角;然后,考虑电液复合转向系统的不确定和干扰问题,利用ADRC算法对目标转向盘转角和实际驾驶人的转向盘转角差值以转矩信号的形式进行补偿。同时研究车道保持系统对驾驶人的干预问题,引入干预系数的概念,采用模糊控制的方法,将驾驶人手力和车辆的运动状态作为输入变量,干预系数作为输出变量,保证整车行驶安全性的前提下减小车道保持辅助系统对驾驶人的干预。最后,通过MATLAB/Simulink仿真和硬件在环试验对所设计的控制策略进行验证。研究结果表明：所设计的基于商用车电液复合转向系统的车道保持策略能够及时地纠正因驾驶人的分心驾驶而导致车辆偏离所在行驶车道的行为,特别是在弯道处出现驾驶人转向不足或过度转向的情况时,能够将车辆维持在车道线之内,保证车辆的行驶安全性,同时由于干预系数的设计,使得驾驶人也有良好的人机交互体验感。     

Resistance torque control for steer-by-wire system to improve human–machine interface

A steer-by-wire system, which has no mechanical constraints between steering wheel and front wheel, is expected to improve steering performance. The mechanical resistance torque is not transmitted from the front wheel to the steering wheel, and it is essential to simulate the torque around the steering wheel for better human-machine interface. Previous studies investigated resistance torque control originating from vehicle behaviour variables such as yaw rate and lateral acceleration. However, other variables such as steering wheel angle and front wheel actuation force are also good candidate sources to generate resistance torque. In this paper, first, four general guidelines are introduced to evaluate three types of resistance torques, i.e., the steering wheel angle origin, the steering force origin and the vehicle behaviour origin. First two guidelines are for ‘driver-made’ phase to make a turn, while the third guideline is for ‘vehicle-made’ phase to return to straight driving and the fourth one is the applicability guideline. Satisfaction of these guidelines by each of the three resistance torques is examined by the actual vehicle experiment. A necessity of combining these three types of resistance torques is indicated as a future subject.     

Steering torque control using variable impedance models for a steer-by-wire system

This paper presents a novel sensor-less steering torque control method for applications to the steer-by-wire system. A steer-by-wire system has not any mechanical link to connect a steering wheel and a rack and pinion gear module. Instead of mechanical devices, two electric motors are used on each side. A one motor is attached to the steering wheel and the other is set on rack and pinion. The motor on the steering wheel works as a deliverer between a steering torque and load torque from the road. In this paper, we focus on motion control related to the steering feel based on impedance control. Therefore, the model of rack and pinion is not considered in this work. In most power steering systems, a torque sensor is used to set impedance effect on driver’s steering feel. In this paper, we proposed a novel steering control method without using any torque sensors. The effectiveness of a proposed method is confirmed from experimental results.     

分布式驱动电动汽车转向工况转矩分配控制研究

针对分布式驱动车辆转向工况在低速下期望提高转向机动性能，高速下期望保证行驶稳定性的需求，充分考虑转向行驶内外侧车轮的转向关系以及车辆动力学，制定了适应车速变化的四轮转矩分配策略，建立了四轮轮毂电机驱动模型以及二自由度参考模型。为了改善分布式驱动转向机动性能，建立自抗扰控制器调整内外侧车轮转矩，形成合理的转速差，减小转向半径，以提高转向机动性；对于高速转向行驶稳定性的需求，通过二次规划方法优化分配各车轮驱动力矩，分析轮胎纵横向附着裕度建立目标函数，并加入附加横摆力矩和路面附着力的限制，进行车轮驱动转矩的在线优化分配，提高车辆转向行驶的稳定性；另外为避免2种控制模式转换时驱动转矩突变，根据车速和稳定性参数制定模糊规则决策2种模式的协调系数，保证2种控制模式的平滑过渡。基于CarSim和MATLAB/Simulink进行联合仿真，并搭建硬件在环平台进行试验，对所提出的方法进行验证。结果表明：在低速转向工况下，提出的分配策略能够调节内外侧车轮产生差速效果，与转矩平均分配的策略相比，转向半径有所减小，提高车辆机动性；高速转向工况下，分配策略能够保证车辆稳定转向，与未考虑稳定性控制的分配策略相比，能更好地跟踪目标轨迹，且横摆角速度控制在参考横摆角速度附近，证明了所提控制策略的有效性。     

Influencing driver chosen cornering speed by means of modified steering feel

This paper presents an investigation about influencing the driver's behaviour intuitively by means of modified steering feel. For a rollover indication through haptic feedback a model was developed and tested that returned a warning to the driver about too high vehicle speed. This was realised by modifying the experienced steering wheel torque as a function of the lateral acceleration. The hypothesis for this work was that drivers of heavy vehicles will perform with more margin of safety to the rollover threshold if the steering feel is altered by means of decreased or additionally increased steering wheel torque at high lateral acceleration. Therefore, the model was implemented in a test truck with active steering with torque overlay and used for a track test. Thirty-three drivers took part in the investigation that showed, depending on the parameter setting, a significant decrease of lateral acceleration while cornering.     

利用力矩电机全工况仿真汽车转向盘反力矩

在汽车动态模拟系统中，转向盘反力矩的仿真逼真度影响实验驾驶员的操纵行为，从而影响驾驶模拟实验的准确性。本文系统地阐述了利用力矩电机进行全工况仿真汽车转向盘反力矩的原理、力矩电机的工况分析及稳态误差分析等，为全工况仿真汽车转向盘反力矩提供了一种新方法。     

Nonlinear optimal integrated vehicle control using individual braking torque and steering angle with on-line control allocation by using state-dependent Riccati equation technique

This paper proposes the solution of state-dependent Riccati equation as a nonlinear optimal regulator to stabilise the motion dynamics of the vehicle model subjected to sudden disturbance inputs in the lateral direction. The proposed nonlinear regulator coordinates individually actuated wheel braking torque and steering wheel angle simultaneously in an optimal manner. Performance criteria are satisfied by solving the Riccati equation based on the given cost function subjected to the nonlinear vehicle dynamics. On-line control allocation in terms of optimal brake torque distribution enhanced by optimal wheel steering angle input is achieved. Furthermore, the proposed optimal nonlinear regulator is an active fault-tolerant control system against partial by-wire actuator failures while guaranteeing stability with good performance due to its capability to allocate the individual control inputs in an optimal way. The main aim is to stabilise the motion dynamics of the vehicle model during short-term emergency situations along the desired straight trajectory manageable by average drivers and to provide vehicle stability and handling predictability through the interaction of individual wheel braking and steering actuators. Simulation results are used to illustrate the effectiveness of the proposed methodology.     

电动轮驱动的轿车差速性能试验

电动轮驱动的汽车取消了机械式差速器后,在转向行驶、路面不平及车轮半径不等3种工况下,会出现差速问题。文章进行了实车转向行驶试验和车轮半径不等时的差速试验,验证了对电动轮电机控制按转矩模式控制而转速随动以实现自适应差速的控制策略。电动轮控制器可以实现很好的差速性能,说明采用转矩控制和转速随动的策略是解决汽车电子差速问题的前提和关键。     

基于功能安全的分布式驱动电动汽车前轮失效补偿控制

分布式驱动电动汽车可以实现四轮转矩分配和差动转向,提升整车的动力学控制性能和经济性,但是四轮转矩独立可控的特点也对功能安全提出挑战。当前轮单侧电机出现执行器故障失效情况时,不仅会产生附加横摆力矩降低车辆安全性,差动转向功能的存在还会使车辆严重偏航。基于此,在设计分布式驱动-线控转向一体化底盘的基础上,基于功能安全提出一种分布式驱动电动汽车前轮失效补偿控制策略。首先建立分布式驱动失效动力学模型,分析前轮失效对车辆状态的影响机理,发现单一的驱动转矩截断控制无法满足车辆状态修正需求;其次设计一套备用的线控转向结构,通过变截距滑模控制算法提高切换状态下线控转向系统的转角跟踪性能,并用台架试验验证跟踪的准确性;然后设计自适应失效诊断观测器实时诊断驱动系统的电机故障,在将对应轮进行驱动转矩截断后,通过模型预测控制算法对车轮转矩重新分配实现纵向和侧向的状态跟踪;最后通过仿真和实车试验验证所提失效补偿控制策略的有效性和可用性。研究结果表明：分布式驱动电动汽车前轮单侧电机失效后,备用的线控转向系统能及时矫正前轮转角,所提出的失效补偿控制策略能够快速恢复车辆的稳定性和路径跟踪能力。     

Advanced emergency braking under split friction conditions and the influence of a destabilising steering wheel torque

The steering system in most heavy trucks is such that it causes a destabilising steering wheel torque when braking on split friction, that is, different friction levels on the two sides of the vehicle. Moreover, advanced emergency braking systems are now mandatory in most heavy trucks, making vehicle-induced split friction braking possible. This imposes higher demands on understanding how the destabilising steering wheel torque affects the driver, which is the focus here. Firstly, an experiment has been carried out involving 24 subjects all driving a truck where automatic split friction braking was emulated. Secondly, an existing driver–vehicle model has been adapted and implemented to improve understanding of the observed outcome. A common conclusion drawn, after analysing results, is that the destabilising steering wheel torque only has a small effect on the motion of the vehicle. The underlying reason is a relatively slow ramp up of the disturbance in comparison to the observed cognitive delay amongst subjects; also the magnitude is low and initially suppressed by passive driver properties.     

基于方向盘角度的电动助力转向系统主动回正控制设计

电动助力转向（EPS）系统是在机械转向系统的基础上,加入电动机作为执行机构,使得转向轻便。由于电机转子、减速机构的摩擦阻尼,致使转向系统的回正性能变差。针对系统回正不足,设计了基于方向盘角度信息查表的主动回正控制算法,进行了电控单元（ECU）软、硬件设计。结果表明,该控制策略可使方向盘顺利回到接近中点位置,不过度。