Structural design of an outer tie rod for a passenger car

This study proposes a structural design method for an outer tie rod installed in a passenger car. The weight of the outer tie rod is optimized by using the aluminum alloy Al6082M, which is developed as a steel-substitute material, and applying structural optimization techniques. The high strength aluminum with improved mechanical properties was developed to reduce the weight of the outer tie rod. The newly developed aluminum alloy Al6082M is applied as the material of the outer tie rod. The static strength due to inertia force, durability and buckling performances are considered in the structural design of the outer tie rod. At the proto design stage of a new outer tie rod, it is cost-effective to utilize FE (finite element) analysis to predict each of these performances. In addition, the current trend in the structural design of automobile parts is to use optimization techniques to reduce the weights of the parts. First, for an arbitrary base design, the static strength, the life cycle and the buckling load are calculated to check whether the design satisfies its criteria. Then, the critical performance is selected so as to include its loading condition only in the optimization process. In this study, the metamodel based optimization process using kriging is adopted to obtain the minimum weight satisfying the critical design requirement. Then, the feasibility of the determined optimum shape is investigated against the other performances. Finally, the optimum design of outer tie rod is modified by considering forging efficiency. The performances of the final design are investigated through simulation and experiment.     

Development of a hardware in the loop simulation system for electric power steering in vehicles

In this paper, a hardware-in-the-loop simulation (HILS) system was developed before the development of an electric power steering (EPS) system in a vehicle. This study was focused on the establishment of the HILS system. Driving conditions are simulated with the HILS system. The actual steering input parameters are confirmed on the monitor while driving the HILS system. The steering forces observed in the simulation with the developed HILS system are similar to those in real vehicle tests. The developed HILS system can be applied in the development of various types of EPS systems.     

轨道运输隧道安全疏散系统——以台北捷运为例

台湾近年来新兴轨道运输系统方兴未艾,都市轨道运输系统,因其路线多经过都市闹区,故常采用地下型式兴建,当发生意外事故或灾变时,乘客能否安全逃生必须倚赖系统对隧道内与地下车站之乘客安全疏散所设计的逃生设备及事前完备规划的操作程序;目前台北捷运系统在隧道段及地下车站之灾害处理对策部份,已属成熟,由于台北捷运系统为台湾都会区轨道运输系统最先施作者,其规划设计除参考国外捷运系统之相关规划设计准则外,并融合台北都会区域活动特性而订定了台北捷运系统地下隧道乘客逃生操作程序,本文将台北捷运系统规划隧道安全疏散程序及地下车站乘客疏散原则,作一全面性说明及分析,希望能提供国内其它轨道运输隧道系统安全规划之案例参考.     

Cooperative Estimation Using Vehicle Communications

Summary Each vehicle on a section of highway is potentially a driving condition 'sensor.' For example, a vehicle's speed give can give a clue about the traffic conditions in its section of roadway. By 'cooperative estimation,' we mean a system that uses a communication network to combine the experience of many vehicles into parameter estimates that are more useful than the estimates that any individual vehicle could generate by itself. This paper demonstrates the cooperative estimation concept by showing how it can be used to estimate traffic conditions and road friction without using roadside sensors.     

Application of Sensitivity Analysis to the Development of High Performance Adaptive Hydraulic Engine Mounts

Summary In this paper, the sensitivity analysis is applied to the development of high performance adaptive hydraulic mounts. The analysis allows us to select the most effective design parameters for tuning an adaptive mount to different road and engine conditions. It is shown that in the low frequency road excitation, the upper chamber compliance and inertia of the fluid column in the inertia track are the most influential properties in changing the dynamic stiffness of the hydraulic mount. These properties for the high frequency engine excitations are the upper compliance and the inertia of the fluid column of the decoupler. For tuning the adaptive mount to different road and engine excitation, a global optimization technique is used to find the magnitude of the adjusting parameters to minimize objective functions in low and high frequency excitations. The results indicate significant improvement over conventional hydraulic mounts. It is further shown that when the upper compliance is used as the adjusting parameter, a simple on-off control which is triggered by the engine revolution and vehicle speed is sufficient for tuning the adaptive mount.     

Nonlinear Dynamics of Vehicle Traction

Summary The purpose of this study is to understand the nonlinear dynamics of longitudinal ground vehicle traction. Specifically, single-wheel models of rubber-tired automobiles under straight-ahead braking and acceleration conditions are investigated in detail. Customarily, the forward vehicle speed and the rotational rate of the tire/wheel are taken as dynamic states. This paper motivates an alternative formulation in which wheel slip, a dimensionless measure of the difference between the vehicle speed and the circumferential speed of the tire relative to the wheel center, replaces the angular velocity of the tire/wheel as a dynamic state. This formulation offers new insight into the dynamic behavior of vehicle traction. The unique features of the modeling approach allow one to capture the full range of dynamic responses of the single-wheel traction models in a relatively simple geometric manner. The models developed here may also be useful for developing and implementing anti-lock brake and traction control control schemes.     

Comparative study between Korea and UK: relationship between driving style and real-world fuel consumption

It is known that differences in driving styles have a significant impact on fuel efficiency and driving styles are affected by various factors such as driver characteristics, street environment, traffic situation, vehicle performance, and weather conditions. However, existing knowledge about the relationship between driving style and fuel consumption is limited. Thus, the aim of this study was to analyze the relationship beteen driving style and fuel consumption. The analysis presented in this paper used data from three on-road experiments were conducted independently in two different countries, i.e. South Korea and the United Kingdom. In this study, 91 participants, consisting 44 UK drivers and 47 Korean drivers, were asked to drive approximately 28 km of UK road and 21 km of Korean road, respectively. Driving data, including real-time fuel consumption, vehicle speed, and acceleration pedal usage were collected. The results suggested that driving styles including average vehicle speed and average throttle position were highly correlated with the real-world fuel consumption, and the cultural factors, e.g. road environment, traffic design, and driver’s characteristics affected the driving styles and, consequently, fuel efficiency.     

Modeling and ratio control of an electromechanical continuously variable transmission

A new type of electromechanical continuously variable transmission (EMCVT) was investigated. The EMCVT uses a direct current (DC) motor to push the driving pulley, which in turn changes the transmission ratio without a hydraulic system. This paper introduces the principle of the EMCVT and establishes a dynamic ratio control model. Ratio control strategies using both position and speed closed-loop control are proposed. Simulation results show that the simulation ratio curves of the EMCVT follow pre-designed ratios well for ramp and sine curves. Control software is based on MATLAB/Simulink/Stateflow and MotoHawk platforms. A prototype vehicle equipped with an EMCVT has been developed. Vehicle test results show that the control performance of the EMCVT satisfies the requirements of vehicle operation. The effectiveness of the EMCVT ratio control strategy proposed in this paper is validated with test data for the prototype vehicle.     

Modelling and controlling of car-following behavior in real traffic flow using ARMAX identification and Model Predictive Control

Nowadays, car following models, as the most popular microscopic traffic flow modeling, are increasingly being used by transportation experts to evaluate new Intelligent Transportation System (ITS) and Advanced Driver Assistance Systems (ADAS) applications. The control of car following is essential due to its safety and its operational efficiency. For this purpose, this paper builds a model of car following behavior based on ARMAX structure from a real traffic data set and presents a Model Predictive Control (MPC) controller. An important advantage of this type of control is its ability to cope with constraints on controls. Since safety and operational efficiency are constraints for car following, therefore we have recruited this type of controller in this study to deal with these constraints. Based on the relative distance and relative acceleration of each instant, the MPC predicts the future behavior of the leader vehicle (LV) and according to this behavior, the acceleration of the follower vehicle (FV) is controlled. The MPC tries to control this acceleration in a way to keep the relative distance at a safe region. To investigate the performance of the designed controller, the result of the system is compared with the behavior of human drivers with similar initial conditions. Also, some other test performances were accomplished to investigate other features such as robustness and the stability of the designed MPC. The simulation results show that the MPC controller has a behavior much safer than that of real drivers and it can provide a pleasant trip for passengers.     

Crashworthiness of chromium plated plastic radiator grille

The use of plastic in vehicle development has increased. In particular, a design trend has resulted in chromiumplated plastics being used in exterior panels. Recently, as the appearance has become more important in design, the plastic radiator grille has become larger, to where it can become the primary member when a front collision happens. The radiator grille should be designed with considerations of the geometric structure, such as delamination, and material characteristics, when plastics are plated with chromium. The enlarged grille has to pass regulations like FMVSS Part 581. Although the material property of plastic has been studied before, what seems to be lacking is study on the crashworthiness of plastic radiator grilles that are plated using chromium. In this paper, in order to evaluate the crashworthiness, tensile test and front collision analysis using finite element method are performed. Tensile test is conducted with 4 types of materials, and then material properties of chromium-plated plastics are obtained. Meanwhile radiator grille’s crashworthiness is evaluated using finite element analysis method. Analysis result is evaluated according to failure criterion. Through this study, method of the assessment of plastic radiator grille’s crashworthiness considered material properties of chromium plated plastics is proposed, and it can be predicted the delamination and the failure point of radiator grille at the design step.