Analysis of torque transmitting behavior and wheel slip prevention control during regenerative braking for high speed EMU trains

The wheel-rail adhesion control for regenerative braking systems of high speed electric multiple unit trains is crucial to maintaining the stability,improving the adhesion utilization,and achieving deep energy recovery.There remain technical challenges mainly because of the nonlinear,uncertain,and varying features of wheel-rail contact conditions.This research analyzes the torque transmitting behavior during regenerative braking,and proposes a novel methodology to detect the wheel-rail adhesion stability.Then,applications to the wheel slip prevention during braking are investigated,and the optimal slip ratio control scheme is proposed,which is based on a novel optimal reference generation of the slip ratio and a robust sliding mode control.The proposed methodology achieves the optimal braking performancewithoutthewheel-railcontactinformation.Numerical simulation results for uncertain slippery rails verify the effectiveness of the proposed methodology.

Determination of the dynamic characteristics of locomotive drive systems under re-adhesion conditions using wheel slip controller

To investigate the re-adhesion and dynamic characteristics of the locomotive drive system with wheel slip controller,a co-simulation model of the train system was established by SIMPACK and MATLAB/SIMULINK.The uniform running and starting conditions were considered,and the influence of structural stiffness of the drive system and the wheel slip controller on the re-adhesion and acceleration performance of the locomotive was investigated.The simulation results demonstrated that the stick-slip vibration is more likely to occur in locomotives with smaller structural stiffnesses during adhesion reduction and recovery processes.There are many frequency components in the vibration acceleration spectrum of the drive system,because the longitudinal and rotational vibrations of the wheelset are coupled by the wheel‒rail tangential force when stick-slip vibration occurs.In general,increasing the structural stiffness of the drive system and reducing the input energy in time are effective measures to suppress stick-slip vibration.It should also be noted that inappropriate matching of the wheel slip controller and drive system parameters may lead to electro-mechanical coupling vibration of the drive system,resulting in traction force fluctuation and poor acceleration performance.

Dynamics and Wheel's Slip Ratio of a Wheel-legged Robot in Wheeled Motion Considering the Change of Height

The existing research on dynamics and slip ratio of wheeled mobile robot （WMR） are derived without considering the effect of height, and the existing models can not be used to analyze the dynamics performance of the robot with variable height while moving such as NOROS- Ⅱ. The existing method of dynamics modeling is improved by adding the constraint equation between perpendicular displacement of body and horizontal displacement of wheel into the constraint conditions. The dynamic model of NOROS- Ⅱ in wheel motion is built by the Lagrange method under nonholonomic constraints. The inverse dynamics is calculated in three different paths based on this model, and the results demonstrate that torques of hip pitching joints are inversely proportional to the height of robot. The relative error of calculated torques is less than 2% compared with that of ADAMS simulation, by which the validity of dynamic model is verified, Moreover, the relative horizontal motion between fore/hind wheels and body is produced when the height is changed, and thus the accurate slip ratio can not be obtained by the traditional equation. The improved slip ratio equations with the parameter of the vertical velocity of body are introduced for fore wheels and hind wheels respectively. Numerical simulations of slip ratios are conducted to reveal the effect of varied height on slip ratios of different wheels. The result shows that the slip ratios of fore/hind wheels become larger/smaller respectively as the height increases, and as the height is reduced, the reverse applies. The proposed research of dynamic model and slip ratio based on the robot height provides the effective method to analyze the dynamics of WMRs with varying height.

Influence of Tire Dynamics on Slip Ratio Estimation of Independent Driving Wheel System

The independent driving wheel system, which is composed of in-wheel permanent magnet synchronous motor（I-PMSM） and tire, is more convenient to estimate the slip ratio because the rotary speed of the rotor can be accurately measured. However, the ring speed of the tire ring doesn’t equal to the rotor speed considering the tire deformation. For this reason, a deformable tire and a detailed I-PMSM are modeled by using Matlab/Simulink. Moreover, the tire/road contact interface（a slippery road） is accurately described by the non-linear relaxation length-based model and the Magic Formula pragmatic model. Based on the relatively accurate model, the error of slip ratio estimated by the rotor rotary speed is analyzed in both time and frequency domains when a quarter car is started by the I-PMSM with a definite target torque input curve. In addition, the natural frequencies（NFs） of the driving wheel system with variable parameters are illustrated to present the relationship between the slip ratio estimation error and the NF. According to this relationship, a low-pass filter, whose cut-off frequency corresponds to the NF, is proposed to eliminate the error in the estimated slip ratio. The analysis, concerning the effect of the driving wheel parameters and road conditions on slip ratio estimation, shows that the peak estimation error can be reduced up to 75% when the LPF is adopted. The robustness and effectiveness of the LPF are therefore validated. This paper builds up the deformable tire model and the detailed I-PMSM models, and analyzes the effect of the driving wheel parameters and road conditions on slip ratio estimation.

The Rolling Wheel Equations without Magic: A Combined Slip-Stiction Approach by the Udwadia-Kalaba Formulation with Constraints Relaxation for a Smooth Simulation

The Udwadia-Kalaba formulation is proposed to model the dynamics of the rolling wheel. A unified approach that addresses both the slip and the stiction in the contact section is considered. Purely rolling constraints are associated with stiction and are suitably lifted as slip occurs. An extended formulation for the Uwadia-Kalaba equations of motion is introduced for that matter. It resorts to the weighted minimum norm and the weighted semi-least-squares solutions of the constraints equations. This not only allows a bias on constraints, by an appropriate description of weight functions based on friction, it also leads to a smooth activation or deactivation of selected constraints without rewriting the equations of motion or upsetting their numerical integration.

Slip-Stick Vibrations of Wheelsets and Rail Corrugations

A dynamic space coupling model is developed for simulating the vibrations of wheel/rail systems as well as the torsion and bending vibrations of wheelsets. It is found that the slip stick vibrations of wheelsets are mainly caused and controlled by the crossing excitation or self excitation of the vertical vibrations of the whole system and by the bending vibrations and torsion vibrations of the wheelsets. It is found for the first time that the slip stick vibrations may occur in more than one forms, and one or another of the three kinds of vibrations is excited more strongly. Four typical kinds of slip stick vibrations are enumerated and described. The field investigation on rail corrugations shows that the four kinds of slip stick vibrations are most likely to exist and related with different corrugated features.

四轮独立电驱动越野车驱动力优化控制

为了充分利用四轮独立电驱动越野车各轮转矩独立可控的优势,提高越野车的牵引力和越野能力,提出了一种驱动转矩协调控制策略.根据越野车前后轴载荷预分配驱动电动机转矩,利用基于车轮滑转率-路面附着系数的极值寻求算法实现路面最优滑转率估计.采用比例-积分-微分(proportional-integral-differential, PID)控制-滑模控制(sliding mode control, SMC)和基于状态的驱动力再分配方法实现各轮驱动转矩的协调分配,抑制越野车在恶劣路面条件下的车轮打滑.通过CarSim/MATLAB联合仿真以及硬件在环(hardware-in-the-loop, HIL)测试,进行了爬陡坡、单一附着路面、对开路面及连续起伏路面工况的试验验证.结果表明:提出的控制策略能根据实际工况分配驱动轮的转矩,降低驱动轮滑转率,实现整车驱动力的优化.

基于液压夹轮制动的门式起重机抗风防滑装置研究

门式起重机作为货物装卸机械的主要机型之一,其动态抗风防滑性能是安全使用的关键因素。针对当前动态抗风防滑装置的研究现状,通过分析液压夹轮器防滑机理,利用传感器技术、液压系统和夹轮器,研发一种门式起重机动态液压抗风防滑装置,实现在带电、停电状态下全过程实施制动,制动响应用时短,能满足不同型号起重机抗风防滑需求。通过试验检测,验证了方案可行性与稳定性,已授权实用新型专利。该装置具有较大的推广价值,为相关门式起重机抗风防滑装置的开发设计提供了参考。

基于遗传算法的实测轮轨蠕滑曲线模拟

轮轨黏着-蠕滑特性直接影响着轮轨系统的工作性能和列车的运行安全。为在轮轨接触数值模型中合理地表征实测黏着-蠕滑曲线的影响,在KP模型和改进FASTSIM模型的基础上,提出了黏着-蠕滑特征参数初值计算方法,结合遗传算法设计参数拟合过程并选取合适的适应度函数,形成了一种获取描述轮轨黏着-蠕滑特性特征参数的通用方法,随后以160 km/h速度的实测蠕滑数据为例,分析对比了本文算法拟合蠕滑曲线的计算效率及与理想工况下局部接触结果的差异。研究表明:(1)本文提出的算法在拟合不同速度工况对应的实测黏着-蠕滑曲线时均具有较高的精度,提出的拟合特征参数取值范围提高了遗传算法收敛速度,与遍历法相比计算速度提高18.5倍;(2)考虑潮湿环境实测轮轨黏着-蠕滑曲线时,轮轨黏滑分布、切向接触应力较干态理想工况有显著差异,主要体现在接触斑最大切向接触应力减小、滑动区面积随蠕滑率增大的速度减缓等。本文算法满足车辆-轨道耦合动力学数值仿真要求,可更真实地模拟实际环境条件下的轮轨相互作用。

柔性腿无缘轮黏滞-滑动过程的被动动态行走运动特性分析

为了分析存在摩擦力情况下柔性腿无缘轮的运动步态,分析了柔性腿无缘轮黏滞与滑动两种运动状态相互转换的条件,通过拉格朗日第一类方程建立了系统的动力学模型,在建模时解除了单支撑阶段的切向约束条件,增加了摩擦力项以实现当摩擦力不足时的滑动状态建模.分析了不同摩擦因数下柔性腿无缘轮的运动步态情况,发现了最多可能产生4种运动行为.研究了不同步态对于系统能量的影响,并发现滑动的产生增加了系统在单支撑阶段的动能.利用Newton-Raphson迭代法和庞加莱映射发现了4种运动行为均存在不动点并且轨迹稳定,同时发现柔性腿无缘轮具有滑动的步态有着良好的鲁棒性.通过研究不同初始动能对系统滑动步态的影响,发现了系统动能或者角速度在一定的范围内存在一个极小的停滞区间,使得系统单支撑阶段在通过直立平衡面附近时会产生长时间的滑动,导致系统的不稳定.

A Fuzzy-based Sliding Mode Control Approach for Acceleration Slip Regulation of Battery Electric Vehicle

Due to quick response and large quantity of electric motor torque,the traction wheels of battery electric vehicle are easy to slip during the initial phase of starting.In this paper,a sliding mode control approach of acceleration slip regulation is designed to prevent the slip of the traction wheels.The wheel slip ratio is used as the state variable for the formulation of system dynamics model.The fuzzy algorithm is utilized to adjust the switch function of sliding mode controller.After stability and robustness analysis,the sliding mode control law is transferred into C code and downloaded into vehicle control unit,which is validated under wet and dry road conditions.The experimental results with a small overshoot and a quick response during starting indicate that the sliding mode controller has good control efect on the slip ratio regulation.This article proposes an acceleration slip regulation method that improves the safety during acceleration for battery electric vehicle.

基于LESO的轮式移动机器人滑模轨迹跟踪控制

针对轮式移动机器人在车轮打滑情况下的轨迹跟踪控制问题,提出了一种利用线性扩张状态观测器(Linear Extended State Observer,LESO)和积分滑模面的控制方案。首先,根据车轮打滑情况下的非完整约束条件建立轮式移动机器人的运动学模型。根据动能函数和拉格朗日方程建立其动力学模型。将这两种模型相结合得到力矩与速度相关的数学模型。其次,利用LESO对该数学模型进行扩张,并对总扰动进行估计。基于实际速度与虚拟速度之差设计带有积分项的滑模面,将扰动估计值前馈结合滑模面设计动力学控制器,并给出速度跟踪误差在有限时间内收敛的证明。最后,与基于超螺旋干扰观测器设计的控制方案仿真相比,所提出方案角速度跟踪误差在1 s左右时已趋于零,车轮力矩值稳定在3 N·m左右,且无锯齿抖动,扰动误差在1~5 s时波动更小,5~20 s时未出现明显锯齿抖动,仿真结果表明所提方案跟踪效果更好,抗干扰能力更强,观测精度更高。

车轮打滑对2万吨重载列车纵向冲动影响分析

针对低黏着接触条件下车轮滑行所引起的列车纵向冲动问题,文章建立了“1+1”编组2万吨重载列车-轨道垂纵耦合动力学模型,对比分析电制动工况下不同轮轨接触状态对2万吨列车纵向冲动的影响,分别计算了车轮发生滑行位置和电制动力载荷大小对纵向冲动的影响规律。结果表明,在电制动运行工况下,当列车施加100%电制动力时,列车在湿润、油污和冰雪接触条件下均检测到了车轮滑行,在25%~75%电制动工况下列车仅在冰雪接触条件下检测到了车轮滑行;车轮滑行导致了车钩力的波动,特别是中部机车发生车轮滑行时会引起其前、中、后部车钩力较大幅度波动,并增大中部机车前部车辆压钩力,严重影响列车的平稳运行;随着制动力的降低,低黏着接触状态下的车轮滑行对最大车钩力的影响明显减小。

侧滑和打滑下的轮式移动机器人轨迹跟踪控制

针对未知侧滑和打滑干扰下轮式移动机器人(WMR)轨迹控制中,存在模型不确定性、外部干扰等扰动导致传统滑模控制易出现收敛精度不足、控制输入抖振的问题,提出一种基于非线性扩展状态观测器的自适应二阶滑模跟踪控制方法(ASOSMC-NESO)。首先建立了侧滑与打滑条件下的轮式移动机器人运动学和动力学模型;其次,由反步法设计运动学控制器,为动力学提供虚拟速度;接着,针对外部干扰设计了非线性扩展状态观测器,以估计总扰动;然后,基于二阶积分滑模的思想将积分滑模和非奇异快速终端滑模面相结合,设计了动力学控制器,并给出了控制器稳定性分析。实验结果表明,对比一阶滑模控制方法,该控制方法误差最大值在线性和非线性轨迹下,分别下降约89.53%和16.28%,而且控制输入基本不受干扰影响。由此可见,ASOSMC-NESO能有效提高WMR在未知侧滑和打滑下的控制精度,并有效削减抖振和提升WMR轨迹跟踪鲁棒性。

基于轮轨切向力的防空转/滑行效率计算方法研究

地铁车辆在完成防空转/滑行试验后,通常通过计算防空转/滑行效率来评价车辆防空转/滑行的性能,目前地铁车辆关于防空转/滑行效率缺少统一的计算方法。为解决该问题,文章系统介绍了轮轨黏着机理及特性,对比分析了既有车辆黏着控制策略和防空转/滑行效率计算方法,建立了车辆牵引和制动工况力学模型并提出了一种基于轮轨切向力的防空转/滑行效率计算方法。与现有防空转/滑行效率计算方法相比,该方法同时适用于防空转试验和防滑行试验效率计算,排除了车辆运行阻力对计算结果的影响,在不同试验工况下的计算结果一致性较好。

考虑滚动半径差异的适时四驱汽车限滑控制策略

结合小备胎识别和轮速补偿技术,设计了基于前、后轴附着率相等的限滑前馈控制和基于轴速差的限滑反馈控制,搭建了适时四驱汽车动力学仿真平台,对小备胎识别、轮速补偿、限滑控制的有效性进行了验证。实现了适时四驱汽车中央差速及差速限滑功能,提高了车辆的动力性和行驶稳定性,避免了因滚动半径差异导致的限滑控制功能误触发,解决了因备胎滚动半径小而导致的电控多片离合器异常磨损、烧蚀等问题。

Estimation of Vehicle Speed Based on Wheel Speeds from ASR System in Four-Wheel Drive Vehicles

Three major methods currently in the use of determining vehicle speed based on wheel speeds, the minimum wheel speed, minimum wheel speed corrected by slope method and the Kalman filter method, are analyzed, with merits and defects of each approach stated. Through simulations, the Kalman filter method based on minimum wheel speed shows improved accuracy, in addition to better adaptivity to vehicle reference speed. It also can be used to acceleration ship regulation （ASR） in part-time four-wheel drive vehicles.

Torque Distribution of Electric Vehicle with Four In-Wheel Motors Based on Road Adhesion Margin

With the worsening of energy crisis and environmental pollution,electric vehicles with four in?wheel motors have been paid more and more attention. The main research subject is how to reasonably distribute the driving torque of each wheel. Considering the longitudinal motion,lateral motion,yaw movement and rotation of the four wheels,the tire model and the seven DOF dynamic model of the vehicle are established in this paper. Then,the torque distribution method is proposed based on road adhesion margin,which can be divided into anti ? slip control layer and torque distribution layer. The anti?slip control layer is built based on sliding mode variable structure control,whose main function is to avoid the excessive slip of wheels caused by road conditions. The torque distribution layer is responsible for selecting the torque distribution method based on road adhesion margin. The simulation results show that the proposed torque distribution method can ensure the vehicle quickly adapt to current road adhesion conditions,and improve the handling stability and dynamic performance of the vehicle in the driving process.

免耕播种机鼠笼型地轮参数优化

地轮是免耕播种机的主要工作部件,可为播种机提供播种和施肥动力,地轮的结构与参数影响着播种机的作业质量。为降低滑移率,减少漏播、空穴和施肥量不足等问题,以鼠笼型地轮为研究对象,通过选取地轮直径、地轮轮宽与垂直载荷为试验因素,采用单因素及三因素三水平正交试验设计方法,进行单间试验及方差分析。研究结果表明:影响滑移率和地轮摩擦力主次因素为垂直载荷>地轮直径>地轮轮宽;确定最佳因素组合为垂直载荷350N、地轮直径610mm、地轮轮宽126mm。此时,地轮滑移率值为1.93%,地轮摩擦力值为330N。

四驱动电动汽车坡道行驶ASR控制仿真研究

轮毂电机电动汽车驱动防滑控制能够增加车辆行驶安全性。基于汽车纵向动力学方程和运动学方程,采用UKF算法对车速和道路坡度进行联合估计。采用模糊控制的方法识别汽车当前行驶路面的利用附着系数和最优滑转率。在车速和坡度联合估计与路面识别的基础上,采用PID控制方法对四轮驱动轮毂电机电动汽车进行驱动防滑控制。利用CarSim和MATLAB/Simulink软件进行联合仿真验证。结果表明设计的算法和控制策略准确有效。