Development of a slip control anti-lock braking system model

This paper describes the initial phase of work carried out as part of an on going study investigating the interaction between the tyre, suspension system and an antilock braking system (ABS). The modelling, analysis simulations and integration of results have been performed using an industry standard Multibody Systems Analysis (MBS) program. A quarter vehicle model has been used together with an individual front suspension system represented by interconnected rigid bodies. The tyre model used can be integrated into vehicle handling simulations but only the theory associated with the generation of longitudinal braking forces is described here. An ABS model based on slip control has been used to formulate the braking forces described in this paper. The simulations, which have been performed braking on wet and dry road surfaces, compare the performance of two different tyres.     

Automobile defrosting system analysis through a full-scale model

Adequate visibility through the automobile windshield is of paramount practical significance, most often at very low temperatures when ice tends to form on the windshield screen. But the numerical simulation of the defrost process is a challenging task because phase change is involved. In this study numerical solution was computed by a finite volume computational fluid dynamics (CFD) program and experimental investigations were performed to validate the numerical results. It was found that the airflow produced by the defrost nozzle is highly nonuniform in nature and does not cover the whole windshield area. The nonuniformity also severely affected the heating temperature pattern on the windshield. The windshield temperature reached a maximum in the vicinity of the defroster nozzle in the lower part of the windshield and ranged from 9∼31°C over a period of 30 min, which caused the frost to melt on the windshield. The melting time was under 10 minutes, which satisfied the NHTSA standard. The numerical predictions were in close agreement with the experimental results. Thus, CFD can be a very useful design tool for an automobile HVAC system.     

模型系统

由于私营部门所有权、经营权及最重要的二十世纪九十年代投资，近年来英国铁路得到了新生。国家铁路系统分散成很多独立公司，该行业已经发生了根本性的变化，耘蕾公司銎营着各种各样的活动。传统上国有经营者持有的技术和技巧现在已经转入私营部门，而多领域公司的引入已经从其它行业带来了知识和实践。     

Modelling and model predictive control for a bicycle-rider system

This study proposes a bicycle-rider control model based on model predictive control (MPC). First, a bicycle-rider model with leaning motion of the rider’s upper body is developed. The initial simulation data of the bicycle rider are then used to identify the linear model of the system in state-space form for MPC design. Control characteristics of the proposed controller are assessed by simulating the roll-angle tracking control. In this riding task, the MPC uses steering and leaning torques as the control inputs to control the bicycle along a reference roll angle. The simulation results in different cases have demonstrated the applicability and performance of the MPC for bicycle-rider modelling.     

Analysis process of a steering system using a concept model for idle vibration

This paper describes the development of an optimal design process for a steering column system and supporting system. A design guide is proposed at the initial concept stage of the development process to obtain sufficient stiffness of the steering system while reducing the idle vibration sensitivity of the system. Case studies on resonance isolation are summarized, where vibration modes among the systems are separated by applying a vibration mode map at the initial stage of the design process. This study also provides design guidelines for an optimal dynamic damper system using a CAE (computer aided engineering) analysis. The damper FE (finite element) model is added to the vehicle model to analyze the relation between the frequency and the sensitivity of the steering column system. This analysis methodology makes it possible to achieve target performance in the early design stage and reduction of damper tuning activity after the proto car test stage. Through the proposed steering column system development process, a lightweight vehicle with high stiffness is possible prior to the proto build stage. Furthermore, the improved process is expected to contribute to reducing the overall development period and the number of proto car tests necessary to achieve the desired steering system performance.     

Integration of a single cylinder engine model and a boost system model for efficient numerical mapping of engine performance and fuel consumption

A numerical engine mapping methodology is proposed for the engine performance and fuel consumption map generation. An integrated model is developed by coupling a single cylinder GT-Power® engine model with a MATLAB/ Simulink® based boost system model to simulate a turbocharged diesel engine over the entire engine operating speed and load ranges within reasonable computational constraints. A single cylinder engine model with the built-in multi-zone combustion modeling option in GT-Power® is configured as a predictive engine model. The cycle averaged simulation result from the engine model is used as the boundary conditions of the boost system including intake and exhaust manifolds and a turbocharger. The boost system model developed in MATLAB/Simulink® platform calculates the intake and exhaust conditions which are fed back to the engine model. The integrated system model predicts the performance and fuel consumption of a turbocharged diesel engine with better predictive capability than mean value engine models. Its computational time is fast enough to simulate the engine over the entire engine operation range compared to multi-cylinder engine models.     

Experimental validation of a mathematical model of a reed-valve reciprocating air compressor from an automotive-braking system

Mathematical simulation is the process of designing a model of a real system and then conducting experiments with the simulation to understand the system’s behavior. Mathematical simulation is widely used for investigating and designing compressors, and with a minimal number of simplifying assumptions, mathematical models can be used in conjunction with modern computing tools to solve complicated problems. A considerable amount of previous research has focused on the mathematical modeling of reciprocating air compressors used in automotive braking. The aim of the present work was to experimentally validate the mathematical model for such compressors. We present a simplified and effective mathematical model for estimating compressor performance, and this model can easily be executed using personal computers. Parameters such as compressor speed, discharge pressure and clearance volume were evaluated in terms of their effect on the thermodynamic behavior of compressors. The model can predict cylinder pressure, cylinder volume, cylinder temperature, valve lift and resultant torque at different crank angles; it can also predict the free air delivered and the indicated power of the compressor. Therefore, the model has been validated using experimental results.     

基于多智能主体系统的车道变换模型

为更加真实地反映车道变换行为,建立具有良好性能的车道变换模型,根据抽样调查结果分析了车道变换的基本条件。引入智能主体(Agent)理论,将Agent与车道变换行为联系起来,建立了基于多智能主体系统(Multi-Agent System,MAS)的车道变换模型框架;给出了车辆MAS的结构,抽象了各Agent成员的元组构成,给出了各Agent成员的工作原理与执行流程;基于多智能系统工程方法(Multi-Agent Systems Engineering Methodology,MASEM),给出了车道变换的仿真流程并得到仿真实例。研究结果表明:在2 km长的双向4车道高速公路上,在30 s时间内,利用提出的车道变换模型仿真得到的车道变换车辆次数与实际情况相差8%;在该时段内任意瞬间,正在执行车道变换的车辆数目与实际情况相差仅1.67%。     

基于模糊推断的车辆跟驰模型

在微观交通流模拟中，由于驾驶行为的不确定性，难以建立精确模型。在模糊推断的基础上，以直接自然的语言描述驾驶行为准则，提出了车辆跟驰模型。     

Optimal controller design for a constrained polynomial vehicle system with an input-state linearized model

This paper presents a new controller design method based on a data-mining polynomial algorithm. We show application of a polynomial data-mining algorithm, where an input-state linearized polynomial vehicle model is developed for very low speed operation and, without introducing any processes with fudge factors, control inputs of a nonlinear system are obtained in the original coordinates. We verify the developed modeling method and controller design method through numerical experiments.     

Pressure model based coordinated control of VGT and dual-loop EGR in a diesel engine air-path system

This paper describes a pressure-model-based coordinated control method of a variable geometry turbine (VGT) and dual-loop exhaust gas recirculation (EGR) in a diesel engine air-path system. Conventionally, air fraction or burnt gas fraction states are controlled for the control of dual-loop EGR systems, but fraction control is not practical since sensors for fractions are not available on production engines. In fact, there is still great controversy over how best to select control outputs for dual-loop EGR systems. In this paper, pressure and mass flow states are chosen as control outputs without fraction states considering the availability and reliability of sensors. A coordinated controller based on the simple control-oriented model is designed with practical aspects, which is applicable for simultaneous operations of high pressure (HP) EGR, low pressure (LP) EGR, and VGT. In addition, the controller adopts the method of input-output linearization using back-stepping to solve the chronic problems of conventional pressure-based controllers such as coupling effects between operations of HP EGR, and VGT. The control performance is verified by simulation based on the proven GT-POWER model of a heavy-duty 6000cc diesel engine air-path.     

汽车防追尾碰撞数学模型研究

为了提高车辆在高速行驶状态下的主动安全性能,研究了处于追尾行驶状态的本车与前车的运动学特征;针对前车的不同运动状态分别推导出了跟车距离的计算模型并分析了模型中3个关键参数的随机性和动态性,对制动迟滞时间提出了基于模糊推理的确定方法,对本车制动减速度和前车的运动加速度提出了比较实用的动态测算公式;另外,研究了防追尾碰撞的控制与执行,建立了动态调整安全制动停车距离的神经网络模型,提出了基于危险裕度判别的安全控制方法。     

考虑环境因素的广义用户平衡和广义系统最优配流模型

首先介绍了城市交通网络分析中公平目标和广义费用函数的概念,建立了考虑环境因素的广义用户平衡和广义系统最优配流模型,并用著名的FRANK-WOLFE算法对所给模型进行了求解。最后给出了一个简单算例,并根据配流结果得出了和实际相符的结论。     

Evaluation of a brake assistance system (BAS) using an injury severity prediction model for pedestrians

Through the years, traffic engineers and researchers have developed a variety of countermeasures to enhance pedestrian safety. Pedestrian-vehicle collisions are regarded as the most serious type of accident since they incur high fatality rates. A fundamental concept in developing effective countermeasures is to analyze pedestrian-vehicle collisions scientifically, which can identify the causes of accidents and accident severity. The objective of this study was to investigate the pedestrian safety benefit of the brake assistance system (BAS) and a functional requirement associated with BAS, namely the time needed to safely detect a pedestrian ahead. An injury severity prediction model for pedestrians was developed to systematically evaluate the BAS in this study. Ordered multinomial logistic regression analysis was used to establish a statistical model capable of predicting pedestrian injury severity. In addition to vehicle characteristics, collision speed and pedestrian characteristics were used as independent predictor variables. The outcomes of this study would be useful in directing the development of safety policies and technologies associated with pedestrian safety.     

城市公交网络可靠性的双层规划模型

建立了城市公共交通网络的重图模型，定义了公共交通网络的可靠性指标矩阵，依此建立了城市公交网络可靠性的双层规划模型，其上层模型使整个网络系统可靠且达到最优，而下层模型是一个标准的满足WARDROP第一平衡准则用户平衡模型，最后进行了求解分析。     

AIS型柴油发电机组智能控制系统设计

作者设计的AIS型柴油发电机组控制系统,已经广泛应用于各种军用和民用柴油发电机组的智能控制、实时检测和参数显示以及三遥控制。本文主要介绍控制系统的基本组成、控制方法和技术特点。     

Performance of a methanol reforming system for a fuel cell powered vehicle and system evaluation of a PEFC system

The fuel cell is an environmentally-friendly power source due to high efficiency and cleanness. Considering safety, tractability and infrastructure, a methanol reformer is a candidate for the supply of hydrogen to fuel cell vehicles. However as CO generated by methanol reformers poisons the platinum catalysts of anodes, the operating conditions were studied in order to minimize the CO emissions from the reforming system. This study tested a methanol reforming system including a steam reformer and preferential oxidizer, established the chemical reaction rates of reforming and CO oxidation and calculated the dynamic changes in CO concentration from the reformer using a newly developed simulator.     

Development of a model for an air brake system with leaks and a scheme for the estimation of the steady-state pushrod stroke

Brake systems in trucks are crucial for ensuring the safety of vehicles and passengers on the roadways. Most trucks in the USA are equipped with S-cam drum brake systems and they are sensitive to maintenance. Brake deficiencies such as leaks and out-of-adjustment of the pushrod are a major cause of accidents involving trucks. Leaks in the air brake systems drastically affect braking performance by decreasing the maximum attainable braking pressure and also increasing the time required to attain the same, thereby resulting in longer stopping distances. Out-of-adjustment of the pushrod leads to loss of braking torque even if no leaks are present in the air brake system. In this paper, we present a mathematical model for an air brake system in the presence of leaks, with a view towards developing a diagnostic system for the air brake system based on the models. Additionally, we present a scheme that estimates the severity of leak in terms of the mass flow rate of air leaking from the air brake system to the atmosphere. This scheme can be implemented using a simple look-up table. We also present a steady-state pushrod stroke estimation scheme, based on brake chamber pressure measurements in the absence of any leaks in the air brake system.     

基于C-F推理模型的沥青路面施工专家系统

为了有效解决沥青路面施工中出现的各类技术问题，利用人工智能原理和沥青路面施工技术问题的特点，提出了基于C－F推理模型的沥青路面施工专家系统，在此基础上，具体阐述了沥青路面施工专家系统的知识库，推理机和系统整体结构的构建方法。