Performance evaluation of slim low-risk-deployment dual-type passenger airbag system with dispersed inflation pressure

Motor vehicle passenger airbags have been proven to be effective for reducing the possibility of passenger injury during a crash. However, the inflation of the airbag sometimes causes serious injury when a passenger is positioned close to the airbag. The United States Federal Motor Vehicle Safety Standard (FMVSS) 208 requires the use of a low-riskdeployment (LRD) passenger airbag system. This paper proposes a newly developed airbag system comprising two slim airbags mounted on the instrument panel. A series of tests were conducted using the FMVSS 208 test procedures to demonstrate the effectiveness of the proposed system. It was found that the system not only satisfied the injury criteria of FMVSS 208, but was also effective for protecting passengers of all sizes.     

Bosch VDC系统的控制原理及展望

VDC系统(Vehicle Dynamics Control、车辆动力学控制系统，在美日等国称为VDC，而在欧洲称为ESP，Electronic Stability Program，即电子稳定程序)是Bosch公司1995年推出的用于改善车辆操纵稳定性的一种车辆动力学控制系统。VDC系统包括两个控制回路：控制车辆运动的主控制回路，控制制动和驱动滑移的副控制回路。文中详细介绍了这两个回路的工作原理，并给出了改善车辆操纵稳定性的实例。最后，指出了VDC系统的发展趋势。     

Structural Optimization for Roof Crush Test Using an Enforced Displacement Method

A roof crush test has been utilized to reduce passengers’ injuries from a vehicle rollover. The Federal Motor Vehicle Safety Standards (FMVSS) 216 and the Insurance Institute for Highway Safety (IIHS) perform actual vehicle tests and evaluate the vehicle’s ratings. Nonlinear dynamic response structural optimization can be employed not only for achievement of a high rating but also minimization of the weight. However, the technique needs a huge computation time and cost because many nonlinear dynamic response analyses are required in the time domain. A novel method is proposed for nonlinear dynamic response structural optimization regarding the roof crush test. The process of the proposed method repeats the analysis domain and the design domain until the convergence criteria are satisfied. In the analysis domain, the roof crush test is simulated using a high fidelity model of nonlinear dynamic finite element analysis. In the design domain, a low fidelity model of linear static response structural optimization is utilized with enforced displacements that come from the analysis domain. Correction factors are employed to compensate the differences between a nonlinear dynamic analysis response and a linear static analysis response with enforced displacement. A full-scale vehicle problem is optimized with a constraint on the rigid wall force from the analysis in the design domain.     

Effectiveness of ECE R66 and FMVSS 220 standards in rollover crashworthiness assessment of paratransit buses

The main objective of the presented study was to compare the effectiveness of two standard test procedures for evaluating bus roof integrity: the dynamic rollover test according to UN-ECE Regulation 66 (ECE-R66), and the quasi-static symmetric roof loading according the Federal Motor Vehicle Safety Standard 220 (FMVSS 220). Both tests were applied to a selected Paratransit Bus. The investigation was carried out primarily using a numerical study backed up by experimental validation tests on components and full scale rollover tests. A sensitivity analysis using LS-OPT? was performed to identify the most important structural components influencing the response of the bus in these two tests. The results obtained from this study show that the final outcome of the crashworthiness assessment of the selected paratransit bus depends on the selection of the evaluation standard. Although the two tests are used for the same purpose of roof integrity evaluation, their results are divergent and may lead to different conclusions. The paper presents a discussion on the effectiveness of both standards in evaluating the rollover crashworthiness.     

Analysis of bus rollover protection under legislated standards using LS-DYNA software simulation techniques

A bus rollover is one of the worst vehicle accidents that can occur. Because of the large numbers of passengers, the casualties in a bus rollover are often high and severe. The compliance with rollover safety standards for buses and coaches is mandated by law. This paper presents a comparative analysis of the physical meanings of regulation number 66 of the Economic Commission for Europe (ECE R66) and standard number 220 of the American Federal Motor Vehicle Safety Standards (FMVSS 220). This comparison was carried out using a LS-DYNA finite-element analysis. After performing a comparative analysis following ECE R66 and FMVSS 220 assessments, the investigation further demonstrated the distortion configuration of the vehicle superstructure through the absorbed energy and its distribution over the vehicle and in sections of vehicle superstructure as well as the violation of the passenger compartment under the rollover testing conditions of both ECE R66 and FMVSS 220. Great differences were found between ECE R66 and FMVSS 220 in distortion configuration, reflecting differences in capability and rollover testing conditions. These findings provide a means of evaluating bus superstructure strength and provide guidelines useful in the assessment of regulations applied to the evaluation of bus rollover strength.     

Analysis of a regenerative braking system for Hybrid Electric Vehicles using an Electro-Mechanical Brake

The regenerative braking system of the Hybrid Electric Vehicle (HEV) is a key technology that can improve fuel efficiency by 20∼50%, depending on motor size. In the regenerative braking system, the electronically controlled brake subsystem that directs the braking forces into four wheels independently is indispensable. This technology is currently found in the Electronic Stability Program (ESP) and in Vehicle Dynamic Control (VDC). As braking technologies progress toward brake-by-wire systems, the development of Electro-Mechanical Brake (EMB) systems will be very important in the improvement of both fuel consumption and vehicle safety. This paper investigates the modeling and simulation of EMB systems for HEVs. The HEV powertrain was modeled to include the internal combustion engine, electric motor, battery and transmission. The performance simulation for the regenerative braking system of the HEV was performed using MATLAB/Simulink. The control performance of the EMB system was evaluated via the simulation of the regenerative braking of the HEV during various driving conditions.     

ESC 液压控制单元设计与选型举例

文章根据整车系统和基础制动系统参数,以及AEB系统对ESC系统理论仿真的TTL要求,逆向计算,校验ESC系统液压控制单元的蓄能器参数、进液阀孔径、出液阀孔径、柱塞泵直径、偏心距、电机功率等,是否可以满足ESC增压能力,蓄能器回油能力等要求,以期达到整车性能表现。     

Vehicle stability control system for enhancing steerabilty,lateral stability,and roll stability

The Vehicle stability control system is an active safety system designed to prevent accidents from occurring and to stabilize dynamic maneuvers of a vehicle by generating an artificial yaw moment using differential brakes. In this paper, in order to enhance vehicle steerability, lateral stability, and roll stability, each reference yaw rate is designed and combined into a target yaw rate depending on the driving situation. A yaw rate controller is designed to track the target yaw rate based on sliding mode control theory. To generate the total yaw moment required from the proposed yaw rate controller, each brake pressure is properly distributed with effective control wheel decision. Estimators are developed to identify the roll angle and body sideslip angle of a vehicle based on the simplified roll dynamics model and parameter adaptation approach. The performance of the proposed vehicle stability control system and estimation algorithms is verified with simulation results and experimental results.     

ESC试验方法研究

为了规范电子稳定控制系统(ESC)技术的发展和促进其技术水平的提升,需要不断完善相应的试验评价方法。文章参考国外相关研究机构的研究成果,详细介绍了《FMVSS 126电子稳定控制系统》规定的试验方法、J转向试验和Fishhook试验。为了推动国内ESC技术的发展,汽车产业相关管理部门、研究和试验机构应尽快开始研究并着手制定类似的试验法规;汽车生产企业也应该大力支持开展与ESC相关的研究,尽快实现ESC技术的国产化,提高产业竞争力。     

Adaptive Throttle Control for Speed Tracking

SUMMARY

Electronic throttle control is an important part of every advanced vehicle control system. In this paper we design an adaptive control scheme for electronic throttle that achieves good tracking of arbitrary constant speed commands in the presence of unknown disturbances. The design is based on a simplified linear vehicle model which is derived from a validated nonlinear one. The designed control scheme is simulated using the validated full order nonlinear vehicle model and tested on an actual vehicle. The simulation and vehicle test results are included in this paper to show the performance of the controller. Due to the learning capability of the adaptive control scheme, changes in the vehicle dynamics do not affect the performance of the controller in any significant manner.     

Selection of Actuator Combination in Integrated Chassis Control Using Taguchi Method

This paper presents a method to select the actuator combination in integrated chassis control using Taguchi method. Electronic stability control (ESC), active front and rear steering (AFS/ARS) are used as an actuator, which is needed to generate a control tire force. After computing the control yaw moment in the upper-level controller, it is distributed into the control tire forces, generated by ESC, AFS and ARS in the lower-level controller. In this paper, the weighted pseudo-inverse control allocation (WPCA) with variable weights is used to determine the control tire forces of each actuator. Taguchi method is adopted for sensitivity analysis on variable weights of WPCA in terms of the control performances such as the maneuverability and the lateral stability. For sensitivity analysis, simulation is performed on a vehicle simulation package, CarSim. From sensitivity analysis, the most effective actuator combination is selected.     

Prediction of the cooling factors of a vehicle brake disc and its influence on the results of a thermal numerical simulation

In the process of developing the brake disc, it is necessary that we predict the suitability of the design. In this manner, we can affirm that even the first prototype will satisfy all of the customer homologation requests. Usually those comprise different sequential braking tests in which the maximal achieved temperature is the criterion that governs brake disc suitability. The knowledge of how to predict the behavior of a brake disc in the early pretesting phase has a significant impact on development costs and time. The common method that is used for predicting the temperatures in the brake disc during braking is numerical simulation analysis. With the help of Computational Fluid Dynamics, the flow through a vehicle ventilated brake disc of known geometry was determined, and the wall heat transfer coefficients for all vehicle speeds and brake disc temperatures were calculated. The results were then imported into a thermal numerical simulation of a sequential-braking vehicle test. The results showed that the consideration of cooling factors has a significant impact on temperature courses. To obtain accurate results from the numerical simulation and to simulate the vehicle test precisely, the proper wall heat transfer coefficients must be considered. The proposed method produces more accurate numerical results and enables the development engineer to develop suitable brake disc geometry in the early pretesting phase.     

New procedure to estimate the brake warping in a roller tester

Vehicle systems such as the steering, brakes and suspension greatly influence vehicle safety. Therefore, these systems must be inspected to guarantee that they are functioning correctly and to certify that the vehicle is functioning at a satisfactory safety level. In disc brakes, warping is one of the principal reasons for vibrations and noise, and it contributes to diminished brake efficiency. Currently, the International Motor Vehicle Inspection Committee (CITA) demands disc brake warping inspections occur during periodic motor vehicle inspections (PMVIs); however, the procedure to carry out this inspection is not well defined. In this investigation, the warping phenomenon has been analyzed, and a new inspection procedure is proposed.     

无人驾驶机器人车辆非线性模糊滑模车速控制

为了实现不同行驶工况下车速的精确、稳定控制，提出一种基于非线性干扰观测器的无人驾驶机器人车辆模糊滑模车速控制方法。考虑模型不确定性和外部干扰对车速控制的影响，建立车辆纵向动力学模型。通过分析无人驾驶机器人油门机械腿、制动机械腿的结构、机械腿操纵自动挡车辆踏板的运动，建立油门机械腿和制动机械腿的运动学模型。在此基础上，分别设计油门/制动切换控制器、油门模糊滑模控制器以及制动模糊滑模控制器，并进行控制系统的稳定性分析。油门/制动切换控制器以目标车速的导数为输入来进行油门与制动之间的切换控制。油门模糊滑模控制器和制动模糊滑模控制器以当前车速以及车速误差为输入，分别以油门机械腿直线电机位移和制动机械腿直线电机位移为输出来实现对油门与制动的控制。模糊滑模控制器中，为了减少控制抖振，滑模控制的反馈增益系数由模糊逻辑进行在线调节。模糊滑模控制器中的非线性干扰观测器用于估计和补偿无人驾驶机器人车辆的模型不确定性与外部干扰。仿真及试验结果对比分析表明：本文方法能够精确地估计和补偿无人驾驶机器人车辆的模型不确定性和外部干扰，避免了油门控制与制动控制之间的频繁切换，并实现了精确稳定的车速控制。     

基于视觉识别的线控制动压力滑模控制

制动安全是车辆主动安全的关键技术之一。制动决策和执行器控制是影响线控制动系统性能的两个主要因素。路面自适应性和控制器鲁棒性分别对制动决策和执行器控制有着重要影响,制约着线控制动系统的发展。本文中以一种液压调控的线控制动系统为基础,针对路面自适应性和控制器鲁棒性问题,提出一种双层结构的制动系统控制器,上层采用计算机视觉的方法对路面类型进行识别,根据识别结果制定当前路面的最佳滑移率;下层针对制动系统参数不确定性问题,引入滑模控制理论对制动过程中的最佳滑移率进行跟踪控制。通过仿真与实验验证,结果表明,双层结构的制动系统控制器相比传统控制器,路面的自适应性好,制动距离更短,控制器鲁棒性好。     

Optimisation of driver actions in RWD race car including tyre thermodynamics

ABSTRACT

The paper presents an innovative method for a lap time minimisation by using genetic algorithms for a multi objective optimisation of a race driver–vehicle model. The decision variables consist of 16 parameters responsible for actions of a professional driver (e.g. time traces for brake, accelerator and steering wheel) on a race track part with RH corner. Purpose-built, high fidelity, multibody vehicle model (called ‘miMa’) is described by 30 generalised coordinates and 440 parameters, crucial in motorsport. Focus is put on modelling of the tyre tread thermodynamics and its influence on race vehicle dynamics. Numerical example considers a Rear Wheel Drive BMW E36 prepared for track day events. In order to improve the section lap time (by 5%) and corner exit velocity (by 4%) a few different driving strategies are found depending on thermal conditions of semi-slick tyres. The process of the race driver adaptation to initially cold or hot tyres is explained.     

Direct tire force generation algorithm based on non-iterative nonlinear inverse tire model

The function of vehicle dynamics control system is adjusting the yaw moment, the longitudinal force and lateral force of a vehicle body through several chassis systems, such as brakes, steering and suspension. Individual systems such as ESC, AFS and 4WD can be used to achieve desired performance by controlling actuator variables. However, integrated chassis control systems that have multiple objectives may not simply achieve the desired performance by controlling the actuators directly. Usually those systems determine the required tire forces in an upper level controller and a lower level controller regulates the tire forces through the actuators. The tire force is controlled in a recursive way based on vehicle state measurement, which may not be sufficient for fast response. For immediate force tracking, we introduce a direct tire force generation method that uses a nonlinear inverse tire model, a pseudo-inverse model of vehicle dynamics and the relationship between longitudinal force and brake pressure.     

一种基于PC486微机的实时硬件闭环模拟系统及应用

本文介绍一种基于ＰＣ４８６微机建造的实时硬件闭环模拟系统，用此系统研究并研制了４ＡＢＳ控制器，描述了系统硬件配置及实现的方法，车辆，轮胎及制动器的建模，给出了模拟结果并进行了控制逻辑的分析。     

智能互联汽车远程诊断测试平台开发

远程诊断系统让主机厂在后台得到并分析车辆售后相关数据,并为车主提供远程服务,其依赖于车辆通信模块和全车控制器的协作。Vector总线开发工具CANoe可以实现虚拟节点和真实节点相结合的仿真。利用该工具,将整车部分控制器和虚拟控制器相结合,搭载远程诊断测试平台。通过测试平台,可以在整车项目前期,对远程诊断的功能进行验证,提高整车开发效率,同时能够同步协助智能互联IT平台的开发工作。     

某车型前后桥制动器匹配设计

为满足整车制动性能要求,对主机厂提供的参数进行制动力匹配计算,并将计算结果与试验结果进行对比,其制动性能试验结果符合法规GB 12676—1999的相关要求。