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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.

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.

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%.

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.

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.

This paper describes a newly-developed, high-performance RTD,(Resistive Temperature detector), which meets OBD-II monitoring requirements. The OBD-II catalyst monitoring requirements are high temperature durability, high accuracy, and narrow piece-to-piece variation. Catalyst monitoring methods have been reviewed and studied by checking the catalyst exotherm(1)(2). The preliminary test results of catalyst monitoring are also described herein.

This paper describes the design concept and evaluation test results of a multi-layered, thick film zirconia NOx sensor which can be used for lean-burn engine management. The oxygen concentration in the measuring gas is lowered to a predetermined level with an oxygen pumping cell, in the first stage. In the second stage, another pumping cell further lowers the oxygen concentration which results in simultaneous NOx decomposition. The second stage pumping current is proportional to the NOx concentration in the measuring gas.

This paper describes a thick film ZrO2 NOx sensor feasible for diesel and gasoline engine applications, and introduces modification items from the previous concept design.(1) The modification items comprise simplifying the sensing element design to reduce output terminals for package design and applying temperature control to the sensing element in order to minimize sensor performance dependency on gas temperature. The NOx sensor indicates a stable linear signal in proportion to NOx concentration in a wide range of temperature, A/F and NOx concentration as a practical condition on both gasoline and diesel engines. The NOx sensor shows a good response in hundred msec. and a sharp signal following NOx generation in a transient state as well. Besides, another type of a NOx sensor is proposed for low NOx measurement in a practical use, by an electromotive force(EMF) voltage instead of a pumping current.

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.

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.

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.

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.

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.

This paper describes the design and property of an electrically heated zirconia exhaust gas oxygen sensor having small-sized and sheet-shaped sensing element. Sensing element and sensor have been miniaturized by monolithic formation of sensing element and heater by means of thick-film techniques. The difference in response property according to the angle of the electrode to exhaust gas flow because of the sheet-shaped configuration of sensing element was minimized by proper design of protective cover. Similarity in λ control property and limit cycle frequency was demonstrated with heated zirconia oxygen sensor having test tube-shaped sensing element by engine dynamometer durability test over 120,000 equivalent miles.

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.

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.

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.

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.

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.

A newly designed, flat, angular-rate sensor consisting of T-shaped vibrating resonators using a single quartz crystal has been developed for automotive, chassis-control systems and vehicle navigation systems. For these systems, the sensor is required to be highly stable under operating conditions. Our newly developed sensor's performance is highly reliable because the resonator is made of quartz that is highly stable under operating conditions, especially temperature changes. The newly developed quartz angular sensor is easy to fabricate because it has a 2-dimensional structure. This structure facilitates the mass production of the sensor at low cost; a requirement for automotive industry use. The flat sensor (0.3mm thick) is fabricated from z-cut quartz and shows promising performance for automotive applications. The flat structure also has the advantage of being easily mounted in flat, narrow spaces.