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Bad weather conditions such as torrential rain, heavy snow, and thick fog frequently occur worldwide. Vehicle accidents in such bad weather conditions account for a significant portion of all vehicle accidents, and the level of damage is relatively severe compared to other accidents that occur in clear weather. This paper analyzes the driver's driving stability in bad weather conditions, which has such a significant meaning, in various ways through experiments on the inconvenience experienced by the driver. In this study, three levels of bad weather conditions were implemented in a driving simulator environment to evaluate driver inconvenience for six activities. Through driving experiment, quantitative bio-signals and vehicle signals were analyzed in each weather condition. The SD survey was used to assess the driver's inconvenience level for activities performed while driving and analyze the ranking of inconvenience.

Unpredictable faults oriented from ambiguous reasons could occur in an engine of a vehicle. However, there are some symptoms from which an engine is working abnormally before the engine is stalled by faults. In this paper, methods for diagnosis of engine faults by using vibrations are proposed. Through bench tests, to extract features for fault diagnosis, various samples with normal and abnormal conditions are prepared and vibration signals from the block of an engine are measured and analyzed. To consider cost and performance of a sensor, vibrations from a knock sensor signal as well as accelerometers are analyzed. Measured vibration signals are synchronized with signal of the crank position sensor and analyzed to detect which event is involved. Modulation analysis and Hilbert transform are applied to extract features representing the symptoms of engine faults and to indicate when the abnormal event happens, respectively.

Herein, we describe a newly designed model predictive control algorithm. When we drive under condition of high speed and high steering, the front wheels of the vehicle experience a large lateral force. This lateral force causes longitudinal deceleration, which naturally reduces the vehicle speed. The model predictive control method used for the high level guidance of autonomous vehicles relies on a kinematic model with three states (x, y, and theta), and this model does not take into account the effect of steering on the longitudinal acceleration. We developed a model predictive controller for extreme maneuvering of autonomous driving vehicles, in which the influence of steering on the longitudinal acceleration is considered during cornering. We verified the improvement in terms of lap time reduction and the ability to track the reference trajectory more accurately.

In this study, SCR system is employed to selectively reduce NOX that is a major cause of environmental pollution from diesel engines. In particular, this paper focuses on urea injection strategies dependent on NO/ NOX ratio. An injection control algorithm is developed based on the chemical ratio between the amount of engine out NOX data obtained from Engine Management System (EMS) and the amount of NH3. Therefore, in order to decide the amount of injection quantity, the NO/NOX ratio from the engine out NOX should be considered in order to minimize NH3 slip while maximizing NOX reduction. Experiments are conducted with a 2.2-liter diesel engine for passenger vehicles with Diesel Oxidation Catalyst (DOC) and Diesel Particle Filter (DPF). Real time control, using Pulse Width Modulation (PWM) duty ratio for dosing module and supply module, is performed by real time computer with its injection control algorithm developed in the Matlab Simulink environment.

Fluctuation in the sound pressure level of the interior noise of an on-road vehicle is always caused by unpredictable factors such as wind gusts, traffic, roadside obstacles, and changing drive-by-drive conditions, and is hence, not reproducible in nature. Since the human brain is known to be more sensitive to noise that is amplitude-modulated than noise at a steady level [1], it is important to evaluate and improve the NVH performance of a vehicle in terms of the fluctuating interior noise likely to be experienced by drivers or users. To this end, an evaluation system was developed as part of this study, the details of which are presented in this paper. The system is composed of hardware for database storage and replay of sounds, and software for synthesizing the noise signals. For given wind tunnel test results, the evaluation system yields a wind noise model that can synthesize wind noise signals for any wind scenario.

In this paper, we propose a hardware and a software design method considering functional safety for an electro-mechanical brake (EMB) control system which is used as a brake actuator in a brake-by-wire (BBW) system. A BBW system is usually composed of electro-mechanical calipers, a pedal simulator, and a control system. This simple by-wire structure eliminates the majority of bulky hydraulic brake devices such as boosters and master cylinders. The other benefit of a BBW system is its direct and independent response; this leads to enhanced controllability, thus resulting in not only improved basic braking performance but also considerably easier cooperative regenerative braking in hybrid, fuel-cell, and electric cars. The importance of a functional safety based approach to EMB electronic control unit (ECU) design has been emphasized because of its safety critical functions, which are executed with the aid of many electric actuators, sensors, and application software.

EMB (Electro-Mechanical Brake) system that removes hydraulic brake device from conventional brake systems completely can be considered as BbW (Brake-by-Wire) system in the full sense. As the research on the EMB system is actively conducted, it is also required to establish the test methods for the performance verification and evaluation of developed EMB system. In fact, however, the characteristics of the EMB system makes it difficult to apply it to an actual vehicle test due to the expense and safety matters in the process of the test and evaluation. Thus, this study developed the EMB HILS (Hardware In the Loop Simulation) system in application of the actual EMB system in order to verify the actuating response characteristics and control logic performance of the EMB system before an actual vehicle test.

The automotive industry is replacing more and more hydraulic systems by electronic system. This not only reduces the weight of vehicles, but also has the potential for a large number of new features [1]. Such a change has led to researches on XbW(X-by-Wire) without the existing mechanical connection and hydraulic system, among which the study on BbW(Brake-by-Wire) in relation to brake devices proceeded to the point of EHB(Electro-Hydraulic-Brake) and then EMB(Electro-Mechanical-Brake). In replacement of existing CBS(Conventional Brake System) with EMB, various advantages such as improvement of response performance and easy combination with various brake applications including ABS and ESC have been found. In fact, however, the problem of fail-safe has remained. This study, therefore, is to develop the control strategy with which the vehicle's longitudinal and lateral motion can follow the driver's steering intention upon failure of one EMB actuator for braking in straight and corner.

In this paper, we suggest a new control algorithm for driver's intention judgment for collision avoidance using a steering system to improve the emergency steering system performance. Most of the collision avoidance systems proposed by previous works relied only on the braking systems. Recently the automotive industry began to consider ways to avoid collisions using the steering system. It is not hard to imagine that any steering-assisted collision avoidance algorithm must judge a driver's intention for lane change before any attempt at longitudinal avoidance is made. To improve the accuracy of driver's intention judgment and thus the performance of the emergency steering system, we developed a new algorithm based on on-center handling characteristics generated by the steering system. The performance of the proposed driver's intention algorithm was validated in the test of real vehicles as well as in the SILS environment.

With the recent development of technologies for interpreting vibration and noise of vehicles, it has become possible for carmakers to reduce idle vibration and driving noise in the phase of preceding development. Thus, the issue of noise generation is drawing keen attention from production of prototype car through mass-production development. J. D. Power has surveyed the levels of customer satisfaction with all vehicles sold in the U.S. market and released the Initial Quality Study (IQS) index. As a growing number of emotional quality-related items are added to the IQS evaluation index, it is necessary to secure a sufficiently high quality level of low-frequency speaker sound against rattle noise. It is required to make a preceding review on the package tray panel, which is located at the bottom of the rear glass where the woofer speakers of a passenger sedan are installed, the door module panel in which the door speakers are built.

In the new product development of vehicle suspension system, the spindle or component loads are very important for optimization of component design for weight and fatigue life. Accurate loads of spindle force at the early stage of vehicle development will help to reduce the number of design changes and there by shortening of the product development cost and time. This paper introduces a reliable method to calculate spindle force. This method requires two models that are tire and road profile. However, precise modeling of tire is not easy because of nonlinear effects between tire and ground. Therefore, new method is proposed which makes the response of the spindle force with a linear tire model be the same as the test result. Virtual road profile is made by using equivalent damage method which is based on frequency response function between road and wheel. This road profile contains the ground characteristics and nonlinear effects between road and wheel.

The selective catalytic reduction system has been known well so far in the reduction of NOx emission in diesel vehicles. On the other hand ammonia slip from SCR reactors must be avoided in the process of catalytic conversion. This research focused to investigate optimal urea injection conditions for urea-SCR system using visualization techniques and evaluate the performance of urea-SCR system in a heavy-duty diesel engine. The parametric study was made on gas temperatures, SVs (space velocity) and ARs (aspect ratio). The urea injector was located at the opposite direction of exhaust gases emitted to an exhaust duct. An optimal quantity of urea and conversion efficient at each mode of ND-13 mode was estimated. Furthermore, NOx emission and applied amounts of urea was investigated with respect to driving modes under the condition of with/without SCR, This research may provide fundamentals for the practical use of urea-SCR in future.

The selective catalytic reduction system has been known well so far in the reduction of NOx emission in diesel vehicles. This research focused to evaluate the performance of urea-SCR system in a heavy-duty diesel engine and was proceed in four steps. First, optimal urea injection conditions for system were developed. Second, optimal geometric conditions for a urea injection system were investigated by a numerical simulation technique. The simulation results contribute to determine the layout of engine test. Before performing engine test, SCR reactor was used to observe basic performance on SCR. This observation was made on effective NOx reduction according to gas temperatures, SVs (space velocity) and ARs (aspect ratio). Finally, the engine test is carried out based on results of above experiments.

In the primary design step, a well established design guide would be useful for vehicle body design engineers, to avoid trial and error for the desired design. In this paper, an integrated design program B-SOPT is presented. The B-SOPT is composed of vibration analysis, section property analysis, and section optimization. Vibration analysis procedure is necessary to evaluate the target frequency constraints for optimization. B.I.W. vibration analysis model can be generated and joint stiffness can also be generated automatically by explicit formula derived from using RSM (Response surface method) in the B-SOPT. The presented design program provides a systematic design guide for the vehicle side body structure. For design engineers, graphic user interface environment is developed with the visual C++ program. A B.I.W design example is given to demonstrate the design procedure using the B-SOPT program.

This paper describes the optimal design process of the steering column system and the supporting system. At the initial concept stage of development process, a design guide is proposed to obtain sufficient stiffness of the steering system while reducing idle vibration sensitivity of the system. Case studies on resonance isolation are summarized, in which separated vibration modes among systems by applying Vibration Mode Map at the initial stage of design process. This study also makes it possible to provide design guideline for optimal dynamic damper system using CAE (computer aided engineering) analysis. The damper FE (finite element) model is added to vehicle model to analyze the relation between the frequency and the sensitivity of steering column system. This analysis methodology enables target performance achievement in early design stage and reduction of damper tuning activity after proto car test stage.

Design optimization of a vehicle is required to increase a product value for noise and vibration performances and for a fuel-efficient car. This paper describes the development process of a high stiffness and lightweight vehicle. A parameter study is carried out at the initial stage of design using the mother car, and a design guide with a good performance is achieved early prior to the development of the proto car. Influences of body stiffness based on the relative weight ratio of the floor and side structures are analyzed. Results show that bending and torsional stiffness has a significant effect on weight distribution ratio. Influences of the distribution of side joint stiffness are analyzed through numerical experiments. Results reveal that the stiffness difference between the upper and lower parts should be small to increase the stiffness of a body.

In this paper, resonance durability analysis is performed for the fatigue life assessment of suspension component considering the dynamic effect of vehicle system. In the resonance durability analysis, the frequency response data and the dynamic load data of frequency domain are used. The multi-body dynamic analysis, finite element analysis and fatigue life prediction method are applied for the resonance durability analysis. To obtain the dynamic load history, the computer simulations running over typical pothole and Belgian road are carried out respectively by utilizing multi-body dynamic vehicle model. The durability estimation for the rear suspension system of the small-sized passenger car is performed by using the resonance durability analysis technique, and the estimation result is compared with the quasi-static durability analysis result. The study shows that the fatigue life considering the resonance frequency of vehicle system can be effectively estimated in early design stage.

An air-conditioner compressor-mounting bracket is a structural component of an engine, on which bolts attach an air-conditioner compressor. In this paper, the shape of the air-conditioner compressor-mounting bracket of a passenger car is optimized using a finite element software, and the optimized bracket is manufactured and verified by tests. An objective function for the shape optimization of the bracket is the weight of the bracket. Two design constraints on the bracket are the first resonant frequency of the compressor assembly and the need not to fracture during the workbench durability test. The compressor assembly, which consists of a compressor, a bracket and connection bolts, is modeled using finite elements. The bracket is modeled by solid elements and the swash-plate-type compressor is represented by rigid masses and beam elements in order to consider the elastic effects of the compressor.

Design for six sigma (DFSS) with sigma based robust design will have a major influence on the future design, if it is applied during the conceptual design phase or design change phase. DFSS will result in more improved but less expensive quality products. This paper presents the implementation of DFSS for robust design of a brake judder of heavy-duty trucks. The problem of brake judder is typically caused by quality defects in manufacturing. However this quality problem can't be controlled deterministically and requires a design considering the uncertainty. In this paper sigma based robust design methodology is applied to improve the brake judder quality problem at the last step of DFSS. Results between conventional deterministic optimization and the proposed sigma based robust design are compared. The robust design by DFSS shows that the manufacturing cost may increase as the quality level increase.

In-vehicle driving tests for evaluating performance of vehicle control devices are often time-consuming, expensive, and not reproducible. Using hardware-in-the-loop simulation scheme, actual control devices can be easily tested in real time in a closed loop with a virtual vehicle. This advantage has made HILS systems popular as testbench lately in automotive industries. This paper describes a PC-based HILS system for ABS that has been developed in Matlab environment with real-time rapid prototyping tools. Also presented in this paper is a semi-empirical vehicle dynamic model that has been designed to account for kinematic and compliant characteristics of the suspension system from rig tests.