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Traction control systems (TCSs) serve to control brake pressure and engine torque, thereby reducing driving wheel spin for improved stability and handling. Systems are divided into two basic types by the brake control configuration. One type is a one-channel left-right common control system and the other is a two-channel individual control system. This paper presents an analysis of these two types of TCS configurations in terms of handling, acceleration, stability, yaw convergence and other performance parameters. The systems are compared with and without a limited-slip differential (LSD) under various road conditions, based on experimental data and computer simulations. As a result of this work, certain Nissan models are now equipped with a new Nissan Traction Control System with a rear viscous LSD (Nissan V-TCS), which provides both the advantages of a rear viscous LSD in a small slip region and a two-channel TCS in a large slip region.

Traffic accidents in Japan claim some 10,000 precious lives every year, and there is seemingly no end to the problem. In an effort to overcome this situation, vehicle manufacturers have been pushing ahead with the development of a variety of advanced safety technologies. Joint public-private sector projects related to Intelligent Transport Systems (ITS) are also proceeding vigorously. Most accidents can be attributed to driver error in recognition, judgment or vehicle operation. This paper presents an analysis of driver behavior characteristics in emergency situations that lead to an accident, focusing in particular on operation of the brake pedal. Based on the insights gained so far, we have developed a Brake Assist System with a Preview Function (BAP) designed to prevent accidents by helping drivers with braking actions. Experimental results have confirmed that BAP is effective in reducing the impact speed and the frequency of accidents in emergency situations.

This paper describes a new 5.6-liter DOHC V8 engine, VK56DE, which was developed for use on a new full-size sport utility vehicle and a full-size pickup truck. To meet the demands for acceleration performance when merging into freeway traffic, passing or re-acceleration performance from low speed in city driving and hill-climbing or passing performance when towing, the VK56DE engine produces high output power at top speed and also generates ample torque at low and middle engine speeds (90% of its maximum torque is available at speeds as low as 2500 rpm). Furthermore, this engine achieves top-level driving comfort in its class as a result of being derived from the VK45DE engine that was developed for use on a sporty luxury sedan. Development efforts were focused on how to balance the required performance with the need for quietness and smoothness.

Traffic accidents in Japan claim some 10,000 precious lives every year, and there is seemingly no end to the problem. In an effort to overcome this situation, vehicle manufacturers have been pushing ahead with the development of a variety of advanced safety technologies. Joint public- private sector projects related to Intelligent Transport Systems (ITS) are also proceeding vigorously. Most accidents can be attributed to driver error in recognition, judgment or vehicle operation. This paper presents an analysis of driver behavior characteristics in emergency situations that lead to an accident, focusing in particular on operation of the brake pedal. Based on the insights gained so far, we have developed a Brake Assist System with a Preview Function (BAP) designed to prevent accidents by helping drivers with braking actions. Experimental results have confirmed that BAP is effective in reducing the impact speed and the frequency of accidents in emergency situations.

A new analysis procedure have been developed that evaluate a brake system performance based on analyses of the transient characteristics and frequency characteritics in the brake piping. Using this procedure, analyses were made of the effect of ABS operation on brake pressure changes and of the influence of the orifice on the pressure transmission characteristics. As an example of a frequency analysis, the pressure transmission characteristics were analyzed when pulse pressure occured in the brake piping as a result of variation in the wall thickness of the brake rotors. This paper presents the results of these analyses and shows the validity of the new procedure through a comparison with experimental data.

Eliminating squeal noise generated during braking is an important task for the improvement of vehicle passengers' comfort. Considerable amount of research and development works have been done on the problem to date. In this study, we focused on the analyses of friction self-excited vibration and brake part resonance during high frequency brake squeal. Friction self-excited vibration is caused by the dry friction between pads and rotor, and occurs as a function of their relative sliding velocities. Its vibration frequency can be calculated in relation to the mass and stiffness of the pad sliding surface. Frequency responses of the brake assembly were measured and the vibration modes of the pad, disc and caliper during squeal were identified through modal analysis. Further study led to the development of a computer simulation method for analyzing the vibration modes of brake parts. Analytical results obtained using the method agreed well with the corresponding experimental data.

This paper describes a study of drag reduction devices for production pick-up trucks with a body-on-frame structure using full-scale wind tunnel testing and Computational Fluid Dynamics (CFD) simulations. First, the flow structure around a pick-up truck was investigated and studied, focusing in particular on the flow structure between the cabin and tailgate. It was found that the flow structure around the tailgate was closely related to aerodynamic drag. A low drag flow structure was found by flow analysis, and the separation angle at the roof end was identified as being important to achieve the flow structure. While proceeding with the development of a new production model, a technical issue of the flow structure involving sensitivity to the vehicle velocity was identified in connection with optimization of the roof end shape. (1)A tailgate spoiler was examined for solving this issue.

An electrically-driven, intelligent brake unit has been developed, to be combined with a regenerative braking system in electric vehicles (EVs) and hybrid electric vehicles (HEVs) which went into production in 2010 - 11. The brake pedal force is assisted by an electrically driven motor, without using vacuum pressure, unlike conventional braking systems. The actuator can be implemented to coordinate with a regenerative braking system, and to have adjustable pedal feel through use of a unique pressure-generating mechanism and a pedal-force compensator. In this paper, we describe features of the actuator mechanism and performance test results

HEV and EV markets are in a rapid expansion tendency. Development of low-cost regenerative cooperation brake system is needed in order to respond to the consumers needs for HEV and EV. Regenerative cooperation brake system which HEV and EV are generally equipped with has stroke simulator. We developed simple composition brake system based on the conventional ESC unit without the stroke simulator, and our system realized a low-cost regenerative cooperation brake. The key technologies are the quiet pressurization control which can be used in the service application, which is to make brake force depending on brake travel, by gear pump and the master cylinder with idle stroke to realize regenerative cooperation brake. Thanks to the key technologies, both the high regenerative efficiency and the good service brake feeling were achieved.

A new 4WD systen called the “ATTESA E-TS” has been developed based on a new approach to traction control. The E-TS system employs electronic control to achieve an optimm torque split ratio between the front and rear axles. This system is designed not only to deliver high tractive performance, but also to improve cornering performance under various road-surface friction coefficients and engine outputs. It consists of a transfer unit containing a multiplate clutch, a hydraulic unit, and a control system which is integrated with an anti-lock brake system and employs a wheel speed sensor at each wheel as well as a lateral acceleration sensor.

Brake judder caused by uneven heat spots on brake disc surfaces is a major issue in improving vehicle quality. This is especially true for rumble that occurs during high-speed braking. In order to determine the excitation mechanism of brake judder, it is necessary to measure the dynamic brake disc geometry and temperature distribution during actual operation on the road. A noncontact sensor system, suitable for a high temperature environment, was used to monitor these parameters, making it possible to visualize heat spots transiently. The data obtained revealed the influence of pad and disc parameters on heat spot formation.

An investigation was made of the relationship between the driving speed at the time of impact and the injury levels suffered in accidents. The results showed that a 5 km/h or more reduction in collision speed tends to mitigate injury severity. Using sensors and brake actuators already in practical use, we have started to research a braking system aimed at reducing the collision speed by at least 5 km/h in rear-end collisions. The system estimates the risk of a collision with the vehicle ahead. If it judges there is a very high possibility of a collision, it applies the brakes.

This report describes an arc-welding robot system with a vision sensor which Nissan Motor Co., Ltd. has introduced to automate the arc welding line for truck frames. Developed in-house, this system is now in operation on the arc welding line for Nissan Truck frames at Nissan's Kyushu plant. In developing the system, primary emphasis was placed on assuring practicality and high reliability. Included among the prominent features of the system is the capability to detect the welding line of thin panels with a high degree of accuracy and to calculate corrections when needed. To assure the high speed and reliability needed for the production line, the robot and sensor are separated, and the vision sensors are placed at fixed positions. Detection of the welding line and transmission of data to the robots to correct their positions are completed just prior to welding, so as to avoid the effects of noise and the arc flash during welding.

JAMA (Japan Automobile Manufactures Association, Inc.)'s guideline for car navigation systems is being decided on displayed the amount of information while driving. The position of a display and the estimated equation, which could be applied from a passenger car to a heavy truck, was studied. The evaluation index was the distance which drivers could become aware of a preceding vehicle by their peripheral vision, because car accidents while drivers glance at an in- vehicle display are almost the rear end collisions. As the results, the lower limit of a position of an in-vehicle display for a passenger car was 30 degrees, and a heavy truck was 46 degrees.

Since the modal density of a drum brake system is higher than that of a disc brake system, it is very difficult to identify the cause of brake squeal. The causes of squeal were examined by both complex eigenvalue analysis and experimental analysis. It was confirmed that a complex eigenvalue analysis of a finite element model, a technique so far generally applied to disc brake squeal studies, was effective in analyzing squeal problems of drum brakes.

This paper presents the electrically driven intelligent brake system that has been developed for electric vehicles, which are expected to penetrate markets rapidly amid the ongoing energy paradigm shift. This brake system achieves a cooperative energy regeneration function and high responsiveness while providing braking performance, system reliability and vehicle mounting ease equal to that of conventional brake systems with a vacuum booster. This paper outlines the newly developed brake system and describes how to decide the target brake force which is achieved a regenerative braking capability for recovering energy efficiently without sacrificing braking.