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Technical Paper

Development of a Multi-Link Beam Rear Suspension for Front-Wheel-Drive Cars

Research into stability at high speed shows that rear suspension characteristics play an important role in vehicle control and stability. In order to improve the cornering limit steering performance and traction of front-wheel-drive vehicles, where the front wheels bear a large proportion of the load and transmit the driving force, and to maintain vehicle stability when decelerating while cornering, rear suspension characteristics are needed that will fully draw out the cornering force capacity of the rear tires. This requirement continues to grow every year, along with demands for higher levels of comfort in passenger cars, including improved ride quality and quietness. It was against this background that the new multi-link beam rear suspension, which is installed in the new Maxima and Sentra models, was developed. This paper describes the aims, construction, characteristics and effects of this new suspension, with focus on vehicle control and stability.
Technical Paper

Trends in Vehicle Information Displays in the Multimedia Era

Flat panel displays for automobiles are facing a new era with the development of navigation systems. As navigation systems become more important as driver's assistance devices, development of birds-eye-view and 3D displays continues, as well as improvements for larger display screens and higher mounting positions. In response to the progress of mobile multimedia technologies, demands for larger display screens and larger aspect ratios have been increasing. Significance for improvements to anti-glare features or view angles has increased as they provide better visibility and the increase layout options. The use of human machine information interaction, which interfaces visual, audio and tactile senses, makes it possible to realize safer, more convenient and comfortable multimedia era vehicle
Technical Paper

Development of Electronically Controlled Air Suspension System

This paper discusses the key components of a new electronically controlled air suspension system developed by Nissan Motor Co. The system utilizes a very soft spring rate, and effectively controls the spring rate and the damping coefficient to achieve high suspension performance. As a result, this system improves both riding comfort and vehicle controllability, two factors that normally conflict with each other. The soft spring rate delivers a comfortable ride, and accurate controllability prevents the vehicle's attitude from changing significantly during roiling, braking and accelerating.
Technical Paper

Development of a Method for Predicting Comfortable Airflow in the Passenger Compartment

Indexes of thermal comfort, such as PMV (Predicted Mean Vote: ISO-7730), which have traditionally been applied to houses or buildings, are difficult to be applied to the automotive passenger compartment because of the large thermal differences that exist around vehicle occupants. In this work, the effects of temperature, airflow and solar radiation on passenger comfort in an air-conditioned vehicle interior were analyzed. Based on the results obtained, a method was devised for predicting the feeling of comfort passengers get from the thermal atmosphere in the vehicle interior. This paper explains the necessity of providing a diffused airflow in an air-conditioned passenger compartment, based on the effects of airflow on the feeling of comfort. Further, a new airflow control procedure is proposed which combines both diffused and concentrated airflow patterns to create a new variable airflow system.
Technical Paper

Study of Comfortable Sitting Posture

By nature, the driver's seat should be designed for work, while the passenger's seat should be built for comfort. This means that the functions of the seats are inherently different. Although many studies have been done on the driver's seat, the design and use of the passenger's seat have received little attention. This study examined a comfortable sitting posture in the passenger's seat. The results obtained have led to the development of two new devices. One device makes it possible for the seat cushion to move upward and forward as the seat tilts backward. The other device allows the upper portion of the seat back to tilt forward from the top of the lower seat back. These devices thus function to provide a comfortable sitting posture. This paper describes the new devices and presents the results of an investigation into a comfortable sitting posture for the occupant of the front passenger's seat.
Technical Paper

Technological Trends in Automotive Electronics

Although automotive electronics was initially applied as a substitute for mechanical parts, this technology has the potential to achieve effective combinations of mechanical functions. A case in point is the successful resolution of fuel consumption and exhaust emission problems by effectively integrating engine control and catalyst technologies. LSI technology has also been incorporated into automotive electronics and established as a fundamental engine control tool. Thanks to LSI technology, particularly the use of microprocessor techniques, conventional machine design problems have been transformed into logical design ones. In the next stage of application, automotive electronics is expected to provide further benefits including a more comfortable ride, an improved human-machine system interface, and an advanced communications system between vehicles and other telecommunications stations.
Technical Paper

The Development of the Suspension System Used on the Nissan Stanza - A New Front-Wheel-Drive Compact Car

The suspension system of the Nissan Stanza was specifically designed for use on a front-wheel-drive car. It was developed with the idea that the new suspension should be compact and light, and afford a comfortable ride as well as good stability and controllability. Furthermore, it should have excellent noise and vibration characteristics. To achieve these objectives we adapted a strut suspension for both the front and rear, and careful consideration was given to the fundamental specifications. In addition, some new ideas were applied for the layout of the suspension.
Technical Paper

A New Electrochromic Device for Automotive Glass - The Development of Adjustable Transparency Glass

A new transparent type electrochromic device (ECD) has been developed. It consists of two electrochromic thin films facing each other, one of “prussian blue” (PB) and the other of tungsten trioxide (WO3). PB exhibits a high intensity of coloration and is blue in the oxidized state and transparent in the reduced state. By electrodeposition, the PB layer can be formed on large substrates at low cost. This ECD has been applied to large, curved automotive glass. It reversibly turns from dark blue to transparent at low operating voltage and maintains the same intensity of coloration without the aid of an external power supply. Compared with photochromic glass, it achieves a greater color change in a shorter time and its light absorption can be changed at will. It shields passengers from the discomfort of glare and heat flow through glass.
Technical Paper

Electronically Controlled Shock Absorber System Used as a Road Sensor Which Utilizes Super Sonic Waves

An important factor in the development of vehicle suspensions has been how to get higher performance from both ride and stability, which are normally in conflict. In addressing this problem, we analyzed the optimum damping forces of shock absorbers for various driving conditions and developed an electronically controlled shock absorber system, which we call “Super Sonic Suspension” based on the results. Through this microcomputer-controlled system, we achieved a great improvement in riding comfort by being able to the damping force much lower than before, based on the results of said analysis. At the same time, stability of the vehicle was also improved by optimumly controlling the damping force for various driving conditions through signals from a newly developed road sensor, which utilizes supersonic waves, and other sensors.
Technical Paper

A System for Neutralizing Static Electricity on the Human Body in a Vehicle

People often feel discomfort when entering or exiting a vehicle because of a static electric shock. In the electronics industry, ionizers have been developed to prevent electrostatic discharges and contamination sticking around or on circuit components. Ionizers incorporate corona discharge principles to neutralize the static electric field. Using this idea, we developed an in-vehicle system to neutralize the human body charge. To accomplish this, the mechanism by which the human body attains a charge when exiting a vehicle was first defined. That definition was then used to determine the design characteristics of the system.
Technical Paper

Prediction of Seat Vibration with a Seated Human Subject Using a Substructure Synthesis Method

A seat vibration prediction technique using a substructure synthesis method was developed for use in ride comfort evaluations. The human body was modeled as a vibration transfer matrix using the mean apparent mass of human subjects, based on data measured in advance. Seat vibration characteristics were measured with rigid masses on the seat. The measured data and vibration transfer matrix of the human body were synthesized using a substructure synthesis method, to predict vibration of the seat cushion and backrest in an occupant-loaded condition without actually using human subjects. Results showed that seat vibration predicted with this method was very similar to, and more repeatable than, that obtained experimentally with human subjects.
Technical Paper

Development of a New 5.6L Nissan V8 Gasoline Engine

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.
Technical Paper

Virtual Occupant Model with Active Joint Torque Control for Muscular Reflex

Riding comfort on the seat is one of the important factors for vehicle comfort. To analyze riding comfort, there were some models for predicting human vibrations in the past studies. On the other hand, it is strongly affected by human body motion caused by vehicle excitation during driving especially low frequency, but it is difficult to predict human motion due to an unclear mechanism of muscle reflex. The purpose of this study is to construct virtual riding comfort testing simulation based on virtual prototyping of the seat. In this study, a virtual occupant model that predicts occupant motion on the seat against external excitation including muscle reflex for maintaining sitting posture constructed. The whole body was modeled as 15 segments biomechanical model (1D) with wobbling mass. Each joint has passive elastic torque and damping torque springs. Human body surface was modeled as rigid shape.
Journal Article

Brain Waves Measurement Based Evaluation of Mental Workload Related to Visual Information While Driving

In order to build a useful and comfortable in-car human machine interface systems, the information presentation method should be easy to understand (low mental workload) and one should be able to respond with ease to the information presented (low response workload). We are making efforts to establish an evaluation method that would differentiate between mental workload and response workload. Here, we present the results of our trial using brain waves measurements (Eye Fixation Related Potentials). We focus on the relation between P3 latencies and drivers response workload compared to mental workload in a task involving eye movements. Previous experiments showed that P3 latency correlates strongly with the amount of information presented. The current experiment shows that P3 latencies seem to be independent to the type of response the subject is requested to perform.