A modified integral sliding mode control to lateral stabilisation of 4-wheel independent drive electric vehicles

This paper presents a novel sliding mode controller (SMC) and its application in the lateral stability control of a 4-wheel independent drive electric vehicle. The structure of the SMC is modified and online-tuned to ensure vehicle system stability, and to track the desired vehicle motion references when an in-wheel motor fault happens. The proposed controller is faster, more accurate, more robust, and with smaller chattering than common SMCs chatter. The effectiveness of the introduced approach is investigated through conducted simulations in the CARSIM and MATLAB software environments.     

电动轮汽车车速与道路坡度估计

针对电动轮汽车车速与道路坡度估计问题,本文中基于纵向非线性动力学方程设计1阶扩张状态观测器对车速与坡度进行联合估计,分析了估计稳态误差;同时,采用带遗忘因子的递归最小二乘估计算法分离加速度传感器信号中的坡度信息,并设置了比例系数来融合两类坡度信息,最终得到道路坡度估计值。搭建MATLAB/Simulink-Carsim联合仿真平台进行变坡度路面仿真,并在实际坡道路面完成实车测试。仿真与试验结果表明,所提出的方法简单、可行。     

纯电动汽车整车控制器进展

在广泛研究国内外纯电动汽车整车控制器的工作原理和系统结构的基础上．总结了如下特点：国外纯电动汽车整车控制器主要用于结构复杂的四轮驱动纯电动汽车和轮毂电机纯电动汽车中。对于单电机驱动的纯电动汽车,通常由电机控制器代替整车控制器实现控制功能。在国内市场没有纯电动汽车整车控制器产品的生产和销售．整车控制器停留在试验室研发阶段。本文可为企业开发出口纯电动汽车整车控制器和国家制订标准提供参考。     

脉冲路面下轮毂电机偏心对电动汽车平顺性影响

为了分析脉冲路面下轮毂电机偏心对电动汽车平顺性的影响,给出了脉冲路面车轮激励和开关磁阻电机激励的表示。建立了考虑轮毂电机质量和轮毂电机激励的电动汽车平面4自由度振动模型,推导出相应的状态方程和输出向量,确定了脉冲路面平顺性评价指标。实现了脉冲路面车轮激励和轮毂电机激励的仿真,在脉冲路面下进行了4种工况的平顺性仿真和比较。结果表明,脉冲路面下轮毂电机偏心对电动汽车平顺性有着不可忽视的影响,设计电动汽车时需要考虑轮毂电机偏心带来的负效应。     

Comparative study of vehicle tyre–road friction coefficient estimation with a novel cost-effective method

This paper qualitatively and quantitatively reviews and compares three typical tyre–road friction coefficient estimation methods, which are the slip slope method, individual tyre force estimation method and extended Kalman filter method, and then presents a new cost-effective tyre–road friction coefficient estimation method. Based on the qualitative analysis and the numerical comparisons, it is found that all of the three typical methods can successfully estimate the tyre force and friction coefficient in most of the test conditions, but the estimation performance is compromised for some of the methods during different simulation scenarios. In addition, all of these three methods need global positioning system (GPS) to measure the absolute velocity of a vehicle. To overcome the above-mentioned problem, a novel cost-effective estimation method is proposed in this paper. This method requires only the inputs of wheel angular velocity, traction/brake torque and longitudinal acceleration, which are all easy to be measured using available sensors installed in passenger vehicles. By using this method, the vehicle absolute velocity and slip ratio can be estimated by an improved nonlinear observer without using GPS, and the friction force and tyre–road friction coefficient can be obtained from the estimated vehicle velocity and slip ratio. Simulations are used to validate the effectiveness of the proposed estimation method.     

A vehicle ABS adaptive sliding-mode control algorithm based on the vehicle velocity estimation and tyre/road friction coefficient estimations

A sliding-mode observer is designed to estimate the vehicle velocity with the measured vehicle acceleration, the wheel speeds and the braking torques. Based on the Burckhardt tyre model, the extended Kalman filter is designed to estimate the parameters of the Burckhardt model with the estimated vehicle velocity, the measured wheel speeds and the vehicle acceleration. According to the estimated parameters of the Burckhardt tyre model, the tyre/road friction coefficients and the optimal slip ratios are calculated. A vehicle adaptive sliding-mode control (SMC) algorithm is presented with the estimated vehicle velocity, the tyre/road friction coefficients and the optimal slip ratios. And the adjustment method of the sliding-mode gain factors is discussed. Based on the adaptive SMC algorithm, a vehicle's antilock braking system (ABS) control system model is built with the Simulink Toolbox. Under the single-road condition as well as the different road conditions, the performance of the vehicle ABS system is simulated with the vehicle velocity observer, the tyre/road friction coefficient estimator and the adaptive SMC algorithm. The results indicate that the estimated errors of the vehicle velocity and the tyre/road friction coefficients are acceptable and the vehicle ABS adaptive SMC algorithm is effective. So the proposed adaptive SMC algorithm can be used to control the vehicle ABS without the information of the vehicle velocity and the road conditions.     

轮毂电机驱动电动汽车3种构型的平顺性分析

针对轮毂电机驱动电动汽车3种构型,对其平顺性问题展开研究。分别采用滤波白噪声方法和三角形凸块描述随机路面激励和脉冲路面激励。建立了轮毂电机驱动电动汽车3种构型的振动模型,确定了相应的平顺性评价指标。在随机路面和脉冲路面下,采用Matlab/Simulink仿真了轮毂电机驱动电动汽车3种构型的平顺性。研究结果表明,具有吸振结构的构型2和具有悬置结构的构型3与传统悬架的构型1相比,降低了轮毂电机驱动电动汽车随机路面和脉冲路面的平顺性评价指标。     

轮毂电机驱动车辆驱动力控制研究

轮毂电机驱动车辆各轮转矩精确可控且响应迅速的特点适用于越野工况,但越野路面起伏不一且附着条件多变,因此,开发基于越野工况辨识的车辆驱动力控制策略,对提升轮毂电机驱动车辆的纵向行驶稳定性具有重要意义。基于动力学模型分析路面附着与路面几何特征,确定可用于越野工况辨识的车辆特征参数集;针对车轮悬空垂向载荷估计失真现象,且由于地面垂向力的实际变化导致车辆垂向载荷分配比例的改变,修正了垂向载荷的计算;利用各特征参数的差异与越野工况的映射关系判定工况属性,采用模糊识别法界定4种地形工况;驱动力控制上层考虑工况与驾驶员影响因素,通过越野工况辨识结果决策驱动利用系数,作为前馈期望转矩调节权重;中层通过四轮垂向载荷得到转矩分配系数,设计驱动力分配算法;下层针对车辆在越野工况下出现车轮滑转与悬空状态,对车轮进行动态转矩补偿。仿真测试与实车验证表明,越野工况辨识结果与预期相符,驱动力控制策略综合优化了车辆稳定性和动力性。     

Literature review and fundamental approaches for vehicle and tire state estimation*

ABSTRACT

Most modern day automotive chassis control systems employ a feedback control structure. Therefore, real-time estimates of the vehicle dynamic states and tire-road contact parameters are invaluable for enhancing the performance of vehicle control systems, such as anti-lock brake system (ABS) and electronic stability program (ESP). Today's production vehicles are equipped with onboard sensors (e.g. a 3-axis accelerometer, 3-axis gyroscope, steering wheel angle sensor, and wheel speed sensors), which when used in conjunction with certain model-based or kinematics-based observers can be used to identify relevant tire and vehicle states for optimal control of comfort, stability and handling. Vehicle state estimation is becoming ever more relevant with the increased sophistication of chassis control systems. This paper presents a comprehensive overview of the state-of-the-art in the field of vehicle and tire state estimation. It is expected to serve as a resource for researchers interested in developing vehicle state estimation algorithms for usage in advanced vehicle control and safety systems.     

四轮独立驱动电动汽车轮毂电机控制策略的研究

为降低轮毂电机转矩脉动对电动汽车平顺性的影响,提出了开关磁阻电机的控制策略。建立了电机的非线性模型,对电机进行了最优角度控制。针对电机转矩脉动问题,首先在直接转矩分配控制基础上,采用模糊算法对传统PID控制器的参数进行在线整定,其次提出将快速终端滑模控制算法与直接转矩分配相结合的控制策略。仿真结果表明,模糊算法的引入提高了系统的稳定性;而快速终端滑模控制算法不仅提高了系统抗干扰的能力,而且降低了电机的转矩脉动。     

Global force potential of over-actuated vehicles

This paper formulates force constraints of over-actuated road vehicles. In particular, focus is put on different vehicle configurations provided with electrical drivelines. It is demonstrated that a number of vehicles possesses non-convex tyre and actuator constraints, which have an impact on the way in which the actuators are to be used. By mapping the actuator forces to a space on a global level, the potential of the vehicle motion is investigated for the vehicles studied. It is concluded that vehicles with individual drive, compared with individual brakes only, have a great potential to yaw motion even under strong lateral acceleration.     

电动汽车轮边驱动系统驱动方式与特点分析

文章简要介绍了电动汽车轮边驱动系统的驱动形式,分析了轮边驱动系统与传统汽车驱动系统相比的优势与不足,并对其未来发展趋势进行了预测。     

基于滑模自抗扰的电制动系统动态负载模拟

为精准模拟传动系弹性及齿隙作用下电制动系统非线性机械负载,提出了自适应模糊滑模自抗扰的测功机控制算法。首先,针对一款前驱电动汽车,建立融合感应电机模型的车辆及台架机电一体化模型,引入典型正常制动和防抱死制动控制作为测试对象。其次,构建扩张状态观测器估计台架系统未建模动态,以自适应模糊滑模控制测功机实时模拟高度非线性机械负载。最后,开展了制动控制策略台架测试的仿真研究。结果表明:提出的方法可精确模拟电制动系统动态负载,有效提高制动控制算法台架测试精度。     

基于滑模控制的滑移率-减速度混合控制方法

滑移率-减速度混合控制是一种用于线控制动系统中联合控制车轮滑移率与车轮减速度的控制方法,用于降低滑移率控制系统中测量噪声对控制效果的影响。文章对滑移率-减速度混合控制算法做出改进,考虑车速变化的变速趋近律设计一种滑模控制器。针对滑模控制器所需车轮纵向摩擦力不能直接测量的问题,文章以车轮滑移率作为状态变量设计一种基于龙伯格观测器的车轮纵向摩擦力观测器。通过 Matlab 与 Carsim 的联合仿真与改进前控制算法 进行对比,仿真结果表明,改进后算法的控制效果有明显提高。     

Development and validation of a Kalman filter-based model for vehicle slip angle estimation

It is well known that vehicle slip angle is one of the most difficult parameters to measure on a vehicle during testing or racing activities. Moreover, the appropriate sensor is very expensive and it is often difficult to fit to a car, especially on race cars. We propose here a strategy to eliminate the need for this sensor by using a mathematical tool which gives a good estimation of the vehicle slip angle. A single-track car model, coupled with an extended Kalman filter, was used in order to achieve the result. Moreover, a tuning procedure is proposed that takes into consideration both nonlinear and saturation characteristics typical of vehicle lateral dynamics. The effectiveness of the proposed algorithm has been proven by both simulation results and real-world data.     

Contents Index Volume 35 and 36

Active safety systems would benefit from tyre force and friction potential information. Different sensor concepts, including, among others, the EU–funded Apollo–project developed tyre sensor based on optical position detection, are being studied. The sensor can measure tyre carcass deflections with respect to the rim. The carcass deflections can be used to calculate tyre forces and they may be exploited in the estimation of friction potential. The waveforms of the sensor signal are illustrated. The vertical and lateral force estimations are presented with unavoidable compensation parts. The tyre sensor measurements were compared to the measurement–vehicle results and good correlations achieved. Continuing activities are concerned with the estimation of friction potential and the detection of aquaplaning.     

借助计算机仿真技术研究分布式轮毂电机在大型运载车辆中的应用

本文是在"2019年第十届全国大学生方程式大赛"的方程式车辆基础上对轮毂电机应用进行了分析研究,对轮毂电机的发展历史,在运载车辆的应用可行性,电机对车辆的操控影响进行了探究.在新能源汽车政策的大背景下,探索新的发展方向,推广运载新能源车辆在实际生产活动中的广泛运用.     

Design of tyre force excitation for tyre–road friction estimation

Knowledge of the current tyre–road friction coefficient is essential for future autonomous vehicles. The environmental conditions, and the tyre–road friction in particular, determine both the braking distance and the maximum cornering velocity and thus set the boundaries for the vehicle. Tyre–road friction is difficult to estimate during normal driving due to low levels of tyre force excitation. This problem can be solved by using active tyre force excitation. A torque is added to one or several wheels in the purpose of estimating the tyre–road friction coefficient. Active tyre force excitation provides the opportunity to design the tyre force excitation freely. This study investigates how the tyre force should be applied to minimise the error of the tyre–road friction estimate. The performance of different excitation strategies was found to be dependent on both tyre model choice and noise level. Furthermore, the advantage with using tyre models with more parameters decreased when noise was added to the force and slip ratio.     

Lateral load transfer and normal forces estimation for vehicle safety: experimental test

Knowledge of vehicle dynamics data is important for vehicle control systems that aim to enhance vehicle handling and passenger safety. This study introduces observers that estimate lateral load transfer and wheel–ground contact normal forces, commonly known as vertical forces. The proposed method is based on the dynamic response of a vehicle instrumented with cheap and currently available standard sensors. The estimation process is separated into three blocks: the first block serves to identify the vehicle’s mass, the second block contains a linear observer whose main role is to estimate the roll angle and the one-side lateral transfer load, while in the third block we compare linear and nonlinear models for the estimation of four wheel vertical forces. The different observers are based on a prediction/estimation filter. The performance of this concept is tested and compared with real experimental data acquired using the INRETS-MA (Institut National de Recherche sur les Transports et leur Sécurité – Département Mécanismes d’Accidents) Laboratory car. Experimental results demonstrate the ability of this approach to provide accurate estimation, thus showing its potential as a practical low-cost solution for calculating normal forces.