Refine Your Search


Search Results

Viewing 1 to 19 of 19
Technical Paper

Development of a Headway Distance Control System

This paper describes a headway distance control system for platoon driving on an automated highway system (AHS). The system implemented on a test vehicle is described first, followed by a description of a vehicle control method based on the use of throttle and brake actuators. This method makes it possible to obtain the target acceleration and deceleration regardless of the vehicle speed range and the rate of acceleration or deceleration. Experimental and simulation results obtained with this method are presented. A control method is then described that uses inter-vehicle communication and laser radar to maintain a constant headway between vehicles. The results of simulations and driving tests conducted with three vehicles are presented to illustrate that the use of inter-vehicle communication is highly effective in improving headway control performance.
Technical Paper

Development of a Standalone Navigation and Audio-Visual System (Multi-AV System)

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.
Technical Paper

A Highly Accurate Fuel Level Measuring System

With conventional float-type fuel level sensor's, measurement errors when the vehicle is on an incline or going around corners. Now, a highly-accurate measuring system employing an electrostatic capacity sensor is developed for practical application. This sensor is composed of multiple electrode plates formed alone a allows accurate measurement of regaining fuel even in tanks of irregular shapes. Also, since this sensor comes a unit, it is easier to replace. The system furthermore, employs software provided with averaging, memory storage, and permittivity correction functions in order to elminate the effects of fuel level fluctuations and pressure changes within the tank during driving along with the effect of fuels with different permittivity.
Technical Paper

A Study of Laser Radar

Various radar systems have been proposed as collision avoidance sensors for automatic braking and warning applications. Practical use of laser radar systems is near with the introduction of high power, high reliability laser diodes. Utilizing these new devices, a laser radar system has been adapted for measuring the distance to objects in its path. It was first shown that reflectors on the rear of the automobile possess high reflectivity and sharp directivity. Given these characteristics, a compact laser radar system was tested that employed 12W laser diodes and PIN photodiodes. The maximum range of approximately 100 m was obtained. Furthermore, the ability to discriminate other vehicles from roadside objects was achieved by detecting discontinuity in measured distance data through a microprocessor. These results show that the performance of laser radar is comparable to that of microwave radar.
Technical Paper

Navigation Systems Using GPS for Vehicles

A number of reports have been published in recent years concerning research work that is underway in Europe. America and Japan on navigation systems for vehicles. The systems reported on to date employ a variety of position detection sensors, such as geomagnetic sensors, gyrocompasses and loran receivers. However, the literature contains virtually no reports of automobile navigation systems that make use of a Global Positioning System (GPS) as a means of detecting and determining the location a vehicle. The authors have developed a GPS automobile navigation system that is intended to be one subsystem of a cinorehensive on-board information system. The total system incorporates car telephone data communication capabilities as well as various functions for centralized operation of the vehicle equipment. This navigation system can accurately locate a vehicle's position using position data received from GPS satellites together with data supplied by geomagnetic sensors.
Technical Paper

Positioning System with Vision Sensor for Automatic Arc Welding

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.
Technical Paper

New Trends in Electronic Engine Control - To the Next Stage

This paper reviews new engine control technologies and future trends, particularly in mechanical and electrical engine control components, the application of modern control theory, and new advances in sensor technologies. A system which utilizes engine cylinder combustion information is representative of these new trends. Like other such sensor systems, the combustion sensor still has problems which must be overcome before practical application is possible. The factors and problems involved in developing this sensor will be discussed, along with how the relationship between sensing information and engine performance can be used to improve engine performance.
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 Simple Engine Model for Idle Speed Control

This paper describes a simple engine model at idling and it applies particularly to idle speed control. Through linearization in the neighborhood of the nominal operating points (650 rpm), the engine is expressed as a reduced-order constant coefficient state variable (2 state) model. It was produced through the system order-reduction method. The strategy for controlling idle speed uses the Linear Quadratic and Integral (LQI) optimal control theory. The tracking controller was designed using a state variable engine model, and the performance index was minimized. Since state variables are artificially introduced, they are not directly accessible. Therefore, they must be estimated in accordance with a stored dynamic model (i.e. observer), in which the engine dynamic behavior is estimated on the basis of a state variable model which represents the engine's internal states, in determining controlling values.
Technical Paper

Doppler Radar Speed Sensor for Anti-Skid Control System

A 24 GHz doppler speed sensor for skid controls has been developed. The microwave sensor is designed using both waveguide and thin-film technologies and assembled into a small integrated unit measuring 27 x 10 x 9 mm. The radar unit and the control circuitry are housed in a waterproof module of 94 x 140 x 78 mm. Part of the casing forms a horn antenna, which radiates a vertically polarized beam incident at 45° on the road surface, when mounted on the vehicle. The error in speed measuring is usually less than 10 percent.
Technical Paper

Crank-angle-resolved Measurements of Air-fuel Ratio, Temperature, and Liquid Fuel Droplet Scattering in a Direct-injection Gasoline Engine

Simultaneous crank-angle-resolved measurements of gasoline vapor concentration, gas temperature, and liquid fuel droplet scattering were made with three-color infrared absorption in a direct-injection spark-ignition engine with premium gasoline. The infrared light was coupled into and out of the cylinder using fiber optics incorporated into a modified spark plug, allowing measurement at a location adjacent to the spark plug electrode. Two mid-infrared (mid-IR) laser wavelengths were simultaneously produced by difference-frequency-generation in periodically poled lithium niobate (PPLN) using one signal and two pump lasers operating in the near-infrared (near-IR). A portion of the near-IR signal laser residual provided a simultaneous third, non-resonant, wavelength for liquid droplet detection. This non-resonant signal was used to subtract the influence of droplet scattering from the resonant mid-IR signals to obtain vapor absorption signals in the presence of droplet extinction.
Technical Paper

An Exploratory Study of the Driver Workload Assessment by Brain Functional Imaging Using Onboard fNIRS

In making driver workload assessments, it is important to evaluate the driver's level of brain activity because the operation of a motor vehicle presumably involves higher-order brain functions. Driving on narrow roads in particular probably imposes a load on the driver's brain functions because of the need to be cognizant of the tight space and to pay close attention to the surroundings. Test vehicles were fitted with a functional near-infrared spectroscopy (fNIRS) system for measuring bloodstream concentrations at 32 locations in the frontal lobe of the participating drivers in order to evaluate their levels of mental activity while driving on narrow roads. The results revealed significant increases in cerebral blood flow corresponding to the perceived workload. This suggests that increases in cerebral blood flow can be used as an effective index for estimating mental workloads.
Technical Paper

Thermal Imaging Technology using a Thermoelectric Infrared Sensor

This paper describes a low-cost 48 × 48 element thermal imaging camera intended for use in measuring the temperature in a car interior for advanced air conditioning systems. The compact camera measures 46 × 46 × 60 mm. It operates under a program stored in the central processing unit and can measure the interior temperature distribution with an accuracy of ±0.7°C in range from 0 to 40°C. The camera includes a thermoelectric focal plane array (FPA) housed in a low-cost vacuum-sealed package. The FPA is fabricated with the conventional IC manufacturing process and micromachining technology. The chip is 6.5 × 6.5 mm in size and achieves high sensitivity of 4,300 V/W, which is higher than the performance reported for any other thermopile. This high performance has been achieved by optimizing the sensor's thermal isolation structure and a precisely patterned Au-black absorber that attains high infrared absorptivity of more than 90%.
Technical Paper

Application of Background Light Elimination Technique for Lane Marker Detection

An active vision system equipped with a high-speed pulsed light-emitting projector and a high-speed image sensor is proposed and applied to lane marker detection in this paper. The proposed system has the capability to suppress image information obtained from the background light and provides only the image information from the signal light emitted by the projector. This is accomplished by synchronizing image capture with the time of signal light emission. To reduce the power consumption and cost of the system, a relatively low intensity projector is used as the light source. The background illuminance on a bright day can be much higher than that of the signal. To improve the signal-to-background ratio, the signal light is modulated using a pulse width modulation technique. Then, the image is captured using a high-speed camera operating in synchronization with the time the signal light is emitted.
Technical Paper

Reciprocal Measurements of the Vehicle Transfer Function for Road Noise

Road Noise is generated by the change of random displacement input inside the tire contact patch. Since the existing 3 or 6 directional electromagnetic shakers have a flat surface at the tire contact patch, these shakers cannot excite the vehicle in a manner representative of actual on-road road noise input. Therefore, this paper proposes a new experimental method to measure the road noise vehicle transfer function. This method is based on the reciprocity between the tire contact patch and the driver's ear location. The reaction force sensor of the tire contact patch is newly developed for the reciprocal loud speaker excitation at the passenger ear location. In addition, with this equipment, it is possible to extract the dominant structural mode shapes creating high sound pressure in the automotive interior acoustic field. This method is referred to as experimental structure mode participation to the noise of the acoustic field in the vibro-acoustic coupling analysis.
Technical Paper

Unsteady Pressure Analysis of the Wake Flow Behind a Passenger Car Model

This paper describes a system for measuring unsteady pressure at up to 256 spatial points and at frequencies up to 300 Hz. The system consists of commercially available equipment for measuring steady pressures. It is based on the use of electronically scanned pressure (ESP) sensors, 16 A/D converters, and a personal computer to control the whole system and acquire data. The signal outputs through the tubes connecting the pressure taps and the ESP sensors are compensated, as are the phase delays between the scanned signals and the gain variation. A 1/5 scale model of a sedan was used in this experiment. The passenger car model was placed in a wind tunnel equipped with a moving belt, which was operated at the same speed as the uniform flow in the wind tunnel. Pressure measurements were obtained at 252 points in a plane behind the model perpendicular to the uniform flow. Measurements were made with the belt turned on and off.
Technical Paper

Simultaneous Measurement of In-Cylinder Temperature and Residual Gas Concentration in the Vicinity of the Spark Plug by Wavelength Modulation Infrared Absorption

This paper presents a new measurement technique for in-cylinder gas temperature and residual gas concentration during the compression stroke of an internal combustion (IC) engine. This technique is based on the infrared absorption of water vapor by a wavelength modulated laser. Wavelength modulation spectroscopy with second harmonic detection (WMS-2f) was adopted to enable the short-path measurements over a wide range of temperatures and pressures corresponding to the late compression stroke in a typical automotive engine. The WMS-2f signal is detected through a bandpass filter at a width of 7.5 kHz, enabling crank angle-resolved measurements. The temperature is determined from the ratio of optical absorption for two overtone transitions of water vapor in the intake gas mixture, and the H2O concentration is determined from this inferred temperature and the absorption for one of the transitions.
Technical Paper

Development of Adaptive Cruise Control With Low Speed Following Capability

This paper presents a newly developed adaptive cruise control system with low-speed following capability that is designed to reduce the driver's workload in low-speed driving such as in congested traffic. This system incorporates a forward-looking sensor with a wider range of view for improved detection of a preceding vehicle in the same lane. It also has a control algorithm that achieves natural vehicle behavior without any disconcerting feeling, as a result of being constructed on the basis of analyses of driving behavior characteristics at low speed like that of congested traffic. Evaluations conducted on a driving simulator have confirmed that the system is effective in reducing the driver's workload.
Journal Article

Development of a Long-Range Ultrasonic Sensor for Automotive Application

In recent years, short-range sensors like stereo cameras, radar and infrared cameras have become essential components of safety systems and user-friendly convenience systems, such as pre-crash safety or parking assist systems. However, they are generally too expensive to implement on lower-end vehicles. On the other hand, a conventional backup-assistance sonar has a very small coverage area, but it is more cost effective than the above-mentioned sensors. This paper proposes an effective method to increase the range of detection of conventional sensor with the help of a pseudo-Wigner distribution-based likelihood function. The reflected wave detected by maximizing the p-WD-based likelihood function with respect to the parameter related to the time delay. This method is verified in actual experiment and the maximum detection range was found to be extended by about 2.5 times beyond that of the conventional approach.