Search Results

This paper describes the Multi-AV System featured in the 1989 model Nissan Cedric, Gloria, and CIMA. It is composed of a navigation system and an audio-visual system. The former system tracks the location of the vehicle and shows it on a CRT map display. This standalone navigation system has been achieved using a map-matching technique along with a terrestrial magnetic field sensor and wheel speed sensors installed at the wheels. Information on hotels, golf courses, Nissan dealers and other items can be obtained. A CD-ROM is employed as the memory. The audio-visual system consists of a radio, cassette deck, CD player, and TV. The Multi-AV System combines the practicality of a navigation function with the entertainment capabilities of an audio-visual system to satisfy diverse needs.

The influence on vehicle dynamics of braking force distribution to four wheels has been analyzed by computer simulation and experimentation. The analytical results indicate that a suitable braking force distribution control method can improve handling and stability during braking. A new braking force distribution cintrol strategy,using a steering wheel angle feedforward function and a yaw velocity feedback function,is shown to improve vehicle dynamic behavior.

This paper describes a control method to improve straight-line stability without sacrificing natural steering feel, utilizing a newly developed steering system controlling the steering force and the wheel angle independently. It cancels drifting by a road cant and suppresses the yaw angle induced by road surface irregularities or a side wind. Therefore drivers can keep the car straight with such a little steering input adjustment, thus reducing the driver's workload greatly. In this control method, a camera mounted behind the windshield recognizes the forward lane and calculate the discrepancy between the vehicle direction and the driving lane. This method has been applied to the test car, and the reduction of the driver's workload was confirmed. This paper presents an outline of the method and describes its advantages.

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.

An analysis was made of vibration phenomena in the steering system of a vehicle, when the front wheels have some amount of unbalance. The program included vehicle running tests and bench tests to ascertain some of the factors influencing vibration behavior. A mathematical model of the vibration system was simulated on a digital computer in as much detail as possible. The resultant understanding of the dynamics of the system as a whole led to an extensive theoretical analysis of selected key parameters.

Judging from viewpoint of automotive safety and more space by eliminating a spare tire, the development of the run-flat tires is important. Many problems relating to weight increase and usability had to be solved in the course of the development of such tires. The “ N ” type run-flat tire, described in this paper, has a simple structure with reinforced side walls and additional beads to fit the rim flanges. Though this tire system brought about a small amount of weight increase, it needs no special part, therefore the conventional road wheels, air valves and tire changers may be used. We have tested and evaluated this tire system equipped with passenger cars as well as on the test machines. Especially vehicle dynamics such as steering, stability and so forth were tested. The test results indicated that this tire system is practical enough.

This Paper describes a computer-controlled power steering system that has been developed and applied to production vehicles. The system provides full power assist at parking speeds, and gradually decreases assistance with increasing vehicle speed to give a normal unassisted “road feel” at highway speeds. The system enables a driver to choose one assistance characteristic among three choices at the flick of a switch, according to the driver's preference and road conditions. A solenoid-operated bypass valve is used to reduce the hydraulic fluid supply to the steering gear, which results in a heavier steering effort. The most suitable valve characteristic curve which corresponds to the increased pressure in the system due to the applied torque is discussed in this study. It is shown that detection of the velocity of steering wheel rotation and extension of the range of characteristics possible are effective ways to ensure good control over the power assistance.

We worked on developing vehicles for the Dual Mode Bus System, and have completed a system which can be technically put into practical application. This paper introduces an outline of the system and vehicle. As regards the operational stability of the lateral guidance system, analyses, computations using a simulation model, and experiments using test cars were conducted on two types of guidance systems, a linked type, which is to link mechanically the guidance wheel with the steered wheel, and a non-linked type.

Basic vehicle performance, such as Safety, Comfort and Economy, are by dependent on tire performance, and it is the air pressure in the tire which assures this performance. However, tire air has a tendency to leak naturally, making it necessary to check them periodically. Since a deterioration in vehicle performance resulting from a drop on tire air pressure can not be directly felt by the driver, the number of people maintaining their tires sufficiently is relatively few. There have been many tire pressure warning devices developed which advise the driver when the pressure drops below a prescribed level. Differing from conventional devices, the TWD-III features a 7-step digital display (at a pitch of 0.1 kgf/cm2) which shows the pressure of each tire within an optional range, and it also has a flat tire warning function. The employment of echo effect from clystal vibrator resonance precludes the need to attach a power source on the tire.

The expanded application of automotive electronics in recent years has increased the number of control switches, thus necessitating the optimization of their layout around the driver and improvement in operability. As an effective means in improving operability, switches mounted on the steering wheel have been developed, placing controls closer to drivers for easier access while driving. However, since the switches rotate along with the steering wheel, recognition and operation of those switches left a few things to be desired. Recently we developed a "steering wheel with a non-rotating center switch pad" where the pad section with the switches are kept stationary. In this paper we describe the general outline of this development.

This paper describes the development of a vehicle with four-wheel steering in which the rear wheels can be controlled electronically in addition to the conventional front-wheel steering system. In the method for steering the rear wheels, the side-slip angle at the vehicle's center of gravity is maintained at zero, which improves the basic dynamic properties of the vehicle. This approach allows greater maneuverability at low speed by means of counter-phase rear steering and improved stability at high speed through same-phase rear steering. However, the use of counter-phase rear steering to improve maneuverability gives rise to problems in regard to practicality. In addition, continuously controlled four-wheel steering, using counter-phase at low speed and same-phase at high speed, leads to many other problems regarding practicality because of the strong apparent understeer characteristics.

This paper presents a new system for controlling the braking force between the inner and outer wheels in a turn independently. Vehicle cornering performance has improved noticeably in recent years thanks to advances achieved in tire and suspension technology. Due to this improvement, vehicle handling characteristics during braking have taken on added importance. To achieve stabler handling properties during braking in a turn, a new evaluation method is being used at Nissan to analyze vehicle directional stability. The analytical results show that decreasing the yaw moment before wheel locking occurs is effective in achieving stabler handling. An effective approach to decreasing the yaw moment is to control the braking force between the inner and outer wheels independently. Base on these analytical results and experimental data obtained with actual vehicles, a new system has been developed that provides such independent control over the braking force.

Wheels play an important role in determining the aerodynamic drag of passenger vehicles. This is because the contribution of wheels to aerodynamic drag comes from not only the wheels themselves, but also from the interference effect between wheel wakes and the base wake. As far as the authors are aware, there have been no reports about aerodynamic drag sensitivity to wheel shape factors for different vehicle types and different exterior body shapes. The purpose of this study was to clarify CD sensitivity to wheel shape factors for a sedan and an SUV, including different rear fender shapes. Many different wheel configurations were investigated in terms of the CD, base pressure and flow fields in wind tunnel tests. Multiple regression analyses were conducted to clarify CD sensitivity to each wheel shape factor based on the test data. This study revealed high CD sensitivity factors for both the sedan and SUV.