Reliability and safety analysis methodology for identification of drivers’ erroneous actions

Owing to significantly individual differences in everyday driving behavior, it is quite difficult to assess the relative importance of driver errors compared with vehicle faults or road environment anomalies. This paper briefly presents several basic concepts for analysis of driving dependability including driving errors, driving reliability, driver recovery from erroneous actions, and key factors that shape driving behavior. This presentation is followed by construction of a shaping architecture for driving behavior that consists of a perception stage, a decision-making stage, an execution stage and correlativity among stages, in addition to internal feedback from complex traffic states. The causation classification of driving errors is then discussed in the context of three elemental types: perception error, decision-making error and execution error. The emphasis of this paper is on how to quantify driving dependability in order to identify various erroneous driver actions during traffic accidents. Specifically, this paper proposes a methodology to measure the probability of driving errors by considering the driver recovery from erroneous actions. The purpose of model-based driving dependability analysis is to quantitatively and qualitatively analyze the relationship between driving errors and traffic accidents causations.     

Analysis of neck fractures from frontal collisions at low speeds

Neck fracture is a major cause of death in traffic accidents. This pattern of injury normally occurs in a frontal collision or overturn of a vehicle. This study investigates the case of a neck fracture from a low-speed collision. In the examined case, the passenger in the front seat of the car fractured his neck and died. He did not have his seatbelt on when the vehicle slipped on a frozen road surface on a downward slope of a hill and impacted into the shoulder of the road at low speed. In this type of collision, an occupant’s body will be impacted by the windshield or other interior trim of the car. However, in this case, rather unusually, neither body tissue nor fiber remained although the collision involved a broken windshield. Thus, the reason for the passenger death was unidentified. This study applied the computer simulation package Madymo for analyzing the accident. The result of the simulation was that the passenger, who did not wear a seatbelt, moved forward due to inertia. The upper part of the passenger then rotated and lifted when the knee contacted with the dashboard. By evaluating the structural deformation of the vehicle at the front, we deduced that the collision velocity was 30 km/h. Through a computational experiment that was undertaken using Madymo 7.0, NIC was estimated to be 240 m²/s². This result far exceeded the threshold for neck injuries. In particular, in comparison with whiplash injuries, when the passenger’s head directly impacts the roof following a rear-end collision, the bending moment through hyperextension of the neck is greatly increased. In this study, we concluded that the manner of death was the hyperextension of the neck, as the passenger’s head contacted the roof from underneath.     

Improved theoretical modeling of a cyclone separator as a diesel soot particulate emission arrester

Particulate matter is considered to be the most harmful pollutant emitted into air from diesel engine exhaust, and its reduction is one of the most challenging problems in modern society. Several after-treatment retrofit programs have been proposed to control such emission, but to date, they suffer from high engineering complexity, high cost, thermal cracking, and increased back pressure, which in turn deteriorates diesel engine combustion performance. This paper proposes a solution for controlling diesel soot particulate emissions by an improved theoretical model for calculating the overall collection efficiency of a cyclone. The model considers the combined effect of collection efficiencies of both outer and inner vortices by introducing a particle distribution function to account for the non-uniform distribution of soot particles across the turbulent vortex section and by including the Cunningham correction factor for molecular slip of the particles. The cut size diameter model has also been modified and proposed by introducing the Cunningham correction factor for molecular slip of the separated soot particles under investigation. The results show good agreements with the existing theoretical and experimental studies of cyclones and diesel particulate filter flow characteristics of other applications.     

Simplified fatigue durability assessment for rear suspension structure

The eight-channel test rig is widely used in durability assessment of vehicle components while for some cases of rear suspension, this costly instrument is unnecessary. Based on the analysis of structure and forces, a simpler one-channel testing approach is presented for the durability calculation of a dependent rear suspension. Taking a punched rear shock tower as the study object, a FEA strain-stress analysis was first performed to determine the risk area. Then, the entire vehicle test system was created, and the proving ground tests were carried out so that the real strain on the part could be measured. Based on the road test data and the P-S-N curve of the component, the cumulative fatigue damage of a 15,000-kilometer proving ground test road was calculated, and the computational result indicates that the modified structure was safe for durability analysis. Moreover, a standard 50% S-N survival fraction curve was plotted using Corten and Dolan’s method, which can be utilized in the durability analysis for other similar components. Finally, the road test for this modified suspension structure was carried out, and the test result certified that the punched shock tower can be subjected to a 15,000-kilometer proving ground test road without the appearance of fatigue failure.     

Low cost design of parallel parking assist system based on an ultrasonic sensor

This paper presents a low cost design and implementation of a parallel parking assist system (PPAS) based on ultrasonic sensors. Generally, a PPAS requires several types of sensors, such as an ultrasonic sensor, camera sensor, radar sensor and laser sensor for parking space detection. However, our proposed PPAS only requires two ultrasonic sensors on the front and lateral sides for parking space detection. Moreover, a steering angle sensor and wheel speed sensor installed in the vehicle are used to obtain vehicle position information for localization in ultrasonic range data. The hardware architecture of the PPAS based on an electronic control unit (ECU) module, sensor modules and a human machine interface (HMI) module was proposed. Moreover, the software architecture of the PPAS is based on system initialization, scheduling, recognition and a control algorithm. In particular, a novel sensor algorithm was proposed to minimize the vehicle corner error of the ultrasonic sensor. A prototype of the PPAS based on the proposed architecture was constructed. The experimental results demonstrate that the implemented prototype is robust and successfully performs parking space detection and automatic steering control. Finally, the low cost design and implementation of the PPAS was possible due to the cheap ultrasonic sensors, simple hardware design and low computational complexity of the proposed algorithm.     

Analysis of an automotive ground system based on its steady-state model

As more electrical equipment is installed and larger currents are required in vehicles, the automotive ground system becomes more important to guarantee the stable operation of the equipment and efficient power consumption. In this paper, an automotive ground system is analyzed in a steady-state condition, and a simulation model for estimating its ground voltage distribution is described. The automotive ground system is divided into an engine compartment ground and a body ground, and it is modeled as an equivalent resistor network, which is suitable for simulation. By using the developed model, ground voltages are simulated and measurements are taken with a real car. A comparison of the simulation and measurement results shows good agreement, and the validity of the model is confirmed. Then, the factors that dominate the ground voltage level are discussed.     

Estimation of the adhesion force for a disc brake in a skid control condition

The performance of brakes has become important due to increased train speeds. The brake system of a train must possess a large brake force to stop the train safely within a limited stopping distance. However, an excessive brake force deteriorates the ride comfort and causes the train to skid. Therefore, it is necessary to control the brake force within the adhesion force limit. This paper presents an analytical method to estimate the relationship between the brake and adhesion forces of a disc brake system. This method has been applied to the actual disc braking control system of the Korea High-Speed Train (HSR350x), and the adhesion force is estimated in an actual skid condition.     

Model-based control of an electropneumatic brake system for commercial vehicles

A properly functioning brake system is critical for ensuring the safe operation of any vehicle on roadways. Commercial vehicles such as trucks, tractors-trailers and buses are equipped with an air brake system that uses compressed air as the energy transmitting medium. This paper presents a model-based control scheme for an electropneumatic brake system for use in commercial vehicles. A mathematical model for an electropneumatic brake system was developed and corroborated with experimental data. A control scheme was developed based on this model and was used to regulate the pressure of air inside the brake chamber according to a desired pressure trajectory. This control scheme was implemented on an experimental test bench, and its performance was studied for various values of the controller parameter. The control scheme was tested for various desired pressure trajectories reflecting actual brake operation.     

Digital human body model for seat comfort simulation

Using the recent anthropometry of the North American population, human body models were developed for seat comfort simulation. The external geometry of the models was acquired from the three-dimensional whole body laser scan of recruited volunteers in a driving position. The selection criteria for volunteers with standard size and shape were derived from a statistical factor analysis of the Size USA database. As a practical application of the model in a design process, comfortable driving postures were constructed by adopting the cascade prediction model (CPM), which takes into account both interior package layout and the driver’s anthropometry. The detail modeling process of finite element modeling and its validation results against volunteer measurements are introduced.     

企业营销组织的风险模糊评价与预警管理

在对企业营销组织的风险分析的基础上,运用预警管理基本理论,给出了预警体系;讨论了如何动用多级模糊综合评判方法,对企业营销组织的风险进行科学的综合评价,并给出了了营销组织的风险报警的具体方法。