DARMSTADT
`UNIVERSITY OF
`TECHNOLOGY
`
`PROGRESS IN AUTOMOBILE LIGHTING
`
`Department of Lighting Technology
`September 28/29, 1999
`
`ER FOUNTAIN AT MATHILDENHOHE, DARMSTADT
`
`Mercedes EX1026
`U.S. Patent No. 11,208,029
`
`

`

`~ 00 ~
`\.0 ~ N
`
`1, 1 00 =· ~ \.0
`
`~
`
`Volume 5
`
`Dept. of Lighting Technology, Darmstadt University
`
`

`

`dedicated to
`
`Mr. Reinhard Ro,pke
`
`

`

`(o2g,~
`~ / { (
`91:)
`
`28 I 29 September, 1999
`
`Proceedings of the Conference
`
`Lichttechnik Darmstad,t:
`
`Published by
`
`Prof. Dr.-lng. H.-J. Schmidt-Clausen
`Darmstadt University of Technolog,y
`
`UTZ
`Herbert Utz Verlag - Wissenschaft
`Munchen 1999
`
`

`

`ISBN 3-89675-920-5
`
`PAL '99: 2 Volumes, Vol. 5 & Vol. 6; not to be sold separately
`
`Die Deutsche Bibliothek - CIP-Einheitsaufnahme
`Progress in automobile lighting/ Darmstadt, University of Technology,
`Department of Lighting Technology. Publ. by. H.-J. Schmidt-Clausen. -
`Munchen : Utz, Wiss.
`Vol. 5. PAL '99 : 28./29. September, 1999 ; proceedings of the conference/
`Lichttechnik Darmstadt. - 1999
`ISBN 3-89675-920-5
`
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`
`Copyright © 1999 Herbert Utz Verlag GmbH
`
`Druck: drucken + binden gmbh, Munchen
`
`Herbert Utz Verlag GmbH, Munchen
`Tel.: 089-277791-00
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`utz@utzverlag.com
`www.utzverlag.com
`
`

`

`Development of the Phase-I AFS Front Lighting System
`
`Shoji KOBAYASHI, Toshihisa HAYAMI,
`
`Atsushi SUGIMOTO, Hideki UCHIDA
`
`Research & Development Center, Koito Manufacturing Co., Ltd.
`
`ABSTRACT:
`
`Koito Manufacturing Co., Ltd. has been actively engaged in the development of
`an advanced lighting system ensuring remarkably improved safety. For exam(cid:173)
`ple, Koito commercialized the world's first steerable forward lighting system with
`ECU. Koito also proposed and had its advanced lighting system incorporated
`into the ASV (Advanced Safety Vehicle) which is being developed under the
`leadership of the Japanese Ministry of Transport.
`
`In this paper, we will introduce the development concepts and composition for
`our advanced front lighting system and report the evaluation results of the latest
`prototype that we recently manufactured on a trial basis.
`
`1.
`
`Introduction
`
`Japan, an island nation, has over 80 million automobiles operated in a relatively
`small and mountainous land area. An extensive road network covers not only
`cities in plains but also villages in highlands. The types of roads range widely,
`from heavy traffic inter-city trunk roads and city streets to sparse traffic country
`roads. Japan is benefited by a mild climate, although precipitations are ample
`throughout the four seasons while fogs are frequent in many mountain regions.
`
`These conditions give rise to a nation of dense vehicle traffic, and mainly for this
`reason Japan records a large number of traffic accidents. Especially, nighttime
`traffic fatalities are three times more than the daytime death toll, and if rainy
`nights are compared with rainy days the fatality ratio becomes 10 to 1. Conse(cid:173)
`quently, automotive headlamps have an important role to play<1>.
`
`449
`
`

`

`In view of the above traffic situation and in an effort to realize safer and more
`comfortable nighttime driving, Koito Manufacturing Co., Ltd. began the devel(cid:173)
`opment of an advanced front lighting system in the mid-1980s. The concept of
`the development plan is summarized in Table 1<2>.
`
`Table 1: Koito's Concept of Advanced Front Lighting System Development
`
`Phase-II headlamp system
`
`Conventional headlamp Phase-I headlamp
`system
`system
`Optimal lighting performance re-
`Maximum lighting perter- Optimal lighting
`spending to traffic environment;
`performance re-
`Target per- mance permitted by ve-
`lighting performance suited for
`spending to driv-
`hicle design & photomet-
`formance
`automated drivinq
`inq operations
`ric specification
`Automatic control Optimal control responding to in-
`formation on traffic environment
`synchronized with
`through intelligent sensors
`driving control
`
`Beam con-
`trol
`
`Manual beam switching
`
`Completion
`target
`
`----
`
`1990 onward
`
`2000 onward
`
`Aimed at a lighting performance responding to the driver's operations, the
`Phase-I system is intended to achieve a front lighting which provides a clear
`visibility in each different driving situation. The Phase-II system, on the other
`hand, is targeted at achieving an optimal lighting capable of responding to the
`driving environment as well as steering operations; moreover, Phase-II is ex(cid:173)
`pected to suit the future Intelligent Transportation Systems (ITS) which will be
`steered with the aid of a "machine vision" system. Phase-II will be providing a
`nighttime lighting optimal to both human vision and machine vision.
`Research and development of Phase-I was completed arid commercialized by
`Koito for the first time in the world to supply front lighting systems capable of
`controlling the illumination direction in linkage with steering operations. Koito
`also took up the research and development of an advanced front lighting sys(cid:173)
`tem for the Advanced Safety Vehicle (ASV) development project of the Japa(cid:173)
`nese Ministry of Transport during the 1990s<3>.<4>_ Koito is currently engaged in
`the research and development of a Phase-II headlamp system.
`In Europe, the EUREKA Project No.1403 AFS (Adaptive Front-lighting System)
`has been underway since around 1995, and efforts are being exerted to estab-
`
`450
`
`

`

`lish AFS specifications<5>,<5>_ Headlamps being a product distributed worldwide,
`it is desirable to establish a new headlamp photometric specification which is
`globally harmonized at the same time as adjusted to take the road conditions of
`various nations into account. Koito therefore was invited to take part in the
`EUREKA AFS Project as the Japanese representative in order to help establish
`an international AFS specification.
`As a preparation for its participation in the AFS Project, Koito has manufactured
`a Demonstration Vehicle equipped with a environment-responsive Koito AFS.
`This AFS is based on Koito's Phase-I headlamp system technologies. The aim
`of this Demonstration Vehicle is to enable all people concerned in Japan and
`other countries to witness the effectiveness of our Phase-I in improving particu(cid:173)
`larly the nighttime driving visibility under Japan's road conditions. Explained in
`this paper are the lighting concept, lamp/system composition, and evaluation
`results of Phase-I.
`
`Lighting Concept of the Phase-I Headlamp System
`2.
`Due to its varied road conditions, Japan can be considered to provide a world
`showcase of traffic problems. Consequently Koito's Phase-I should provide
`useful data for improved nighttime driving visibility and for developing a world
`AFS specification. While a conventional headlamp system consists of high and
`low beams, it is impossible to respond to all road conditions with just a two(cid:173)
`beam system. More beams are necessary to match varied driving regions, traf(cid:173)
`fic situations, and driving operations. Table 2-1 shows the beam configurations
`and corresponding driving scenes imaged by Koito, and Figure 1 illustrates
`major driving scenes and suitable beam distribution on the road surface.
`
`451
`
`

`

`Table 2-1: Imaged Beam Configurations and Driving Scenes
`
`Beam confiquration
`
`Motorway beam
`
`Abbr.
`MB
`
`CB
`
`TB
`
`AW
`
`BB
`
`HC
`MC
`LC
`cc
`OH
`BD
`
`_-j;:~=~_: _: '-.2 --~··
`
`2 - 4-._
`-..:::..~
`
`Country beam
`
`Town beam
`
`Beam for adverse
`weather
`
`Drivinq scene
`High-speed driving on a 4-lane inter-city
`highway divided by anti-glare median fence
`Driving on a suburban road with many
`curves but with liqht traffic
`Driving on an inner-city street with many pe-
`destrians and intersections
`Driving on a road where lane keeping is dif-
`ficult due to poor visibility of the lane mark-
`ings and road shoulders in adverse weather
`Hiqh-speed cornerinq on hiqhwav, etc.
`Hiqh speed
`Bending Middle speed Cornering on suburban road
`Low-speed cornerino on citv street
`Low speed
`beam
`Crossroads cornering
`Slow-down
`Beam for overhead sign Driving toward overhead sign site
`Beam dipping or dimming (intensity adjust-
`Beam dipping or dim-
`ment)
`ming
`
`Basic
`beams
`
`Additional
`function
`beams
`
`!S)tn
`
`CB+MC
`CB
`Strai ht Curve
`Suburb
`
`TB+LC
`TB
`Strai ht Curve
`lnner-ci
`
`TB+CC
`Intersection
`
`Fig. 1: Imaged Beam Distribution in Major Driving Scenes
`
`452
`
`

`

`The motorway beam (MB), coun,try beam (CB), and town beam (TB) are fun(cid:173)
`damentally the same beam categories as those being discussed in Europe. Ta(cid:173)
`ble 2-2 shows Koito's performance targets for these three basic beams.
`
`Table 2-2:. Performance Targets for Basic Beams
`
`Basic
`beam
`
`MB
`
`CB
`
`Projected driving & stopping distances Distant surface illuminance & beam reach
`
`100km/hr,
`
`112m
`
`80km/hr,
`
`76m
`
`5 Ix,
`
`5 Ix,
`
`120m
`
`80m
`
`50m
`10 Ix,
`32m
`50km/hr,
`TB
`* Stopping distance: The response time required by the dnver for brake pedal operation
`is assumed to be one second.
`
`Furthermore, we are considering additional function beams to supplement the
`three basic beams. These additions are a beam for adverse weather (AW),
`beam for road curves, beam for overhead signs (OH), and beam for dipping and
`dimming at a time of beam switching (BO).
`
`The AW is intended to improve the visibility of road shoulders and lane mark(cid:173)
`ings in a rainy, foggy or another adverse weather. Its target performance is to
`improve the illumination of road shoulder and lane marking sections existing
`between 5m and 20m ahead of the vehicle.
`
`We divide bending beams into a maximum of four categories -- a beam for high-'
`speed cornering (HC), beam for middle-speed cornering (MC), beam for low(cid:173)
`speed cornering (LC), and beam for crossroads cornering (CC). These bending
`beams may be obtained by introducing additional function lamps or by moving
`the aims of basic beams in the horizontal direction.
`
`Figure 2 shows the maximum illumination directions of bending beams. Each
`illumination direction is set on the bending point of a lane as viewed from the
`lamp. The cornering speeds are assumed to be below those of MB, CB and TB
`(Table 2-2) which are the driving speed on straight roads. The illumination di(cid:173)
`rection of CC beam for crossroads cornering is set on the basis of the vehicle's
`minimum turn radius.
`
`453
`
`

`

`Beam
`HC
`MC
`LC
`cc
`
`Road design
`speed
`80km/hr
`40km/hr
`20km/hr
`Slow-down
`speed
`
`Min. cornering
`radius
`280m
`60m
`15m
`Min. turn radius
`Sm
`
`Max. illumination
`direction
`7°
`14°
`30°
`45°
`
`-30
`
`-20
`
`_, t 0
`
`l 0
`
`20
`
`30
`
`ig. 2: Assumed Conditions for Bending Beams 16
`
`In view of the traffic and road conditions in Japan, we believe it particularly nec(cid:173)
`essary to improve illumination of pedestrians at city intersections, illumination in
`adverse weather, and illumination in the bending sections of a road.
`
`3.
`
`Composition of Phase-I Front Lighting System
`
`3-1. Lamp Composition
`Figure 3-1 shows a front view of the Demonstration Vehicle's lighting system
`consisting of a main headlamp (Variable Beam or VB lamp) and three additional
`function lamps. These lamps are intended to satisfy all the beam functions listed
`in Table 2-1, except the illumination of overhead signs. These beams are con(cid:173)
`trolled using information from -a vehicle speed sensor and a steering sensor.
`
`454
`
`

`

`Light shield
`for upcoming
`vehicle
`
`Discharge
`bulb
`
`Fig. 3-1: Front View of Phase-I System
`
`Fig. 3-2: Composition of a VB Lamp
`
`3.1.1. Variable Beam (VB) Lamp
`
`Figure 3-2 shows the composition of a Variable Beam (VB) lamp serving as the
`main headlamp. A projector-type lamp with a discharge bulb, the VB lamp in(cid:173)
`corporates two light shield each independently adjustable by 1.5° upward and
`0.5° downward. One light shield is for the vehicle in front, while the other light
`shield is for the oncoming vehicle. The reflector is made adjustable by up to 7°
`in both right and left directions. For details of the VB lamp structure and photo(cid:173)
`metric performance, consult the referenced document <1>.
`
`A VB lamp is made up of a single lamp unit designed to be response to diverse
`driving situations and steering operations. By combining a VB, a rotatable re(cid:173)
`flector and an adjustable light shield, the Demonstration V.ehicle is capable of
`providing the aforementioned three types of basic beams (in both high and low
`beam stages) plus an HC beam for high-speed cornering.
`
`3.1.2. Additional Function Beam Lamps
`
`Additional function beam lamps are a group of lamps for responding to Japan's
`characteristic road and weather conditions, such as the presence of many road
`bends and intersections and many rainy and foggy days. These lamps supple(cid:173)
`ment the basic beams provided by VB lamps.
`
`455
`
`

`

`~-_::;-: __ ::---0--::..:-:.::_-_
`---
`
`--
`
`' I
`
`-~
`
`VB lamp
`
`HC beams are obtained
`through adjustment of
`the main VB-L photo(cid:173)
`metric axis by up to 7°.
`
`CC lamp
`
`LC lamp
`
`Fig. 3-3: Imaged Illumination Configurations on Road Surface
`
`There are three types of additional function lamps: MC, LC and CC. Figure 3-3
`illustrates the imaged configurations of road surface illumination by these
`lamps. The beam axes of the lamps are aimed at the directions indicated in
`Figure 2. To drive through a road bend at night, the lamps are turned on in or(cid:173)
`der of the MC, LC and CC lamps.
`The MC lamps illuminate especially the lane markings and road shoulder sec(cid:173)
`tion existing between 5m and 20m ahead of the vehicle. The MC lamps there(cid:173)
`fore can function as AW lamps for illumination in adverse weather, and are
`made operative by a wiper switch on the condition that the VB lamps are al(cid:173)
`ready on.
`
`3.2. Composition of Control System
`Figure 3-4 diagrams the working of the control system employed in the Demon(cid:173)
`stration Vehicle.
`
`456
`
`

`

`Sensor signal
`'_;,,;conversion·'
`controller
`
`VB lamp
`controller
`
`.
`
`.----- --------
`: AUT
`: Oscillation
`: I .c1rcwt
`17_s:.
`: Highway
`; I Suburb I+- .
`'~ - -~ .
`~~e s_w1tcn~r.
`· .. ·.
`: ddbrr ooo
`, ____________ _
`D
`
`Dimming . ,> - - - - - - - -C ___ _,!
`...__ _ _ .control u n i t · ' ~ - - - - ' - - - - < = = = = ]
`
`VB-L(L)
`
`VB-L(R)
`
`MC..,.L(L)
`MC-L(R)
`
`LC-L(L)
`LC-L(R)
`CC,L(L)
`CC-L(R)
`
`· 1 . .,
`
`Fig. 3-4: Block Dic1gram qf Phase-I Lamp Control System
`The control system has the following components to realize the target photo.;'
`metric performance:
`
`(1) Sensor signal conversion controller:
`Carries out the overall control of the Phase-.1 front lighting system. lteypl~-
`ates the current vehicle condition using input signals from the vehicle SPE;E:!d
`sensor, steering sensor, and column switch, and outputscommand signals
`'
`to the VB lamp controller and dimming c~ntrol unit.
`
`.
`
`'
`
`.·
`
`.
`
`, .
`
`;
`
`'
`
`.. ,,
`
`'
`
`(2) VB lamp controller (driving of actuators):
`Drives the beam axis and cutoff line control actuators incorporated in the
`VB lamp unit,· in response to commands from the sensor signal conversiO'n
`controller.
`
`(3) Dimming control unit (for lamps other than VB lamps):
`Adjusts the beams of lamps other than the VB lamps, in response to com(cid:173)
`mands from the sensor signal conversion controller.
`
`(4) Mode switch (for demonstration purposes):
`Used to show selection between the motorway, country and town driving
`modes during vehicle halt periods for demonstration purposes.
`
`457
`
`

`

`3.4. Beam Control
`
`Figures 3-5 and 3-6 list the beam control functions of the Phase-I front lighting
`system. The VB lamp has a main-beam stage for situations where there is no
`vehicle in front of the driver, and a sub-beam stage for situations where there
`are vehicles ahead of the driver. These stages are shifted manually from one
`another by a main/sub switch. Then, in each of the main-beam and sub-beam
`stages, one of the following driving mo_des is automatically selected -from vehicle
`speed data:
`
`(1) Town driving: less than 40km/h
`
`(2) Country driving: from 40km/h to less than 90km/h
`
`(3) Motorway driving: more than 90km/h
`
`A hysteresis is attributed to the shift point of each driving mode so as to prevent
`excessive mode shifting by subtle changes in the vehicle speed. The details of
`beam control in each driving mode are explained below:
`
`(1) Town driving mode
`
`The movable beam axes of the VB lamps are fixed at 1.5° outward respec(cid:173)
`tively; as a result, lateral visibility is improved in comparison with that of
`conventional headlamps. In addition, the bending beam lamps turn on ac(cid:173)
`cording to the amount of steering operation.
`
`Note that, in the case of low-speed town driving, busy steering operations
`occur due to frequent lane changes and crossroads turns and consequently
`the vehicle is often steered in directions off the driver's intended course. For
`this reason, the beam axis of the VB lamp is fixed, not linked with steering
`operations, in the town driving mode.
`
`(2) Country driving mode
`
`The beam axes of the VB lamps are rotated between O and 7° outward in
`linkage with steering operations. Other lamps are turned on according to the
`amount of steering operation as in the town driving mode. The CC beam is
`
`458
`
`

`

`inactivated in this driving mode due to a lack of steering operations similar
`to the crossroads turn operations in the town.
`
`(3) Motorway (Highway) driving mode
`
`To increase the distant visibility, the cut off line on the oncoming-vehicle
`side is raised 0.5° and thus is leveled with the cut off line on the front(cid:173)
`vehicle side. Since the steering operation angle is narrowed as the vehicle
`speed increases, a narrower dead band was provided in the center of the
`steering sensor and thus the responsiveness of beam axis control is im(cid:173)
`proved. Only the MC beam is activated according to the amount of steering
`operation, while the other additional function beams are kept inactive in the
`motorway driving mode.
`
`·.
`
`Beam ON 0
`Beam OFF oo
`Lamp
`
`-
`
`Steering angle
`
`-
`
`40° ~ 100° ~ 180° -::::=>
`----- 20° ~ 60°
`100
`
`Driving mode
`Town driving
`0-40km/h
`Country driving
`40-90km/h
`Motorway driving
`90km/h
`
`VB-L
`Main photometric axis control
`Main axis of lamps fixed 1.5° outward,
`respectively
`oo
`70 - -30°
`Steering angle
`- -
`50
`Main axis position 0° ........ 0°
`oo
`50
`Steering angle
`- -
`Main axis position 0° ...... __ . 0°
`
`30°
`50
`
`Cutoff shape
`
`MC-L
`
`LC-L
`
`CC-L
`
`I
`
`...
`
`...
`
`0.5° UP
`
`0
`
`0
`
`0
`
`0
`
`0
`
`X
`
`0
`
`X
`·x
`
`Fig. 3-5: Sub-beam Stage Beam Control in Phase-I Front Lighting System
`
`Steering angle
`
`oo
`Beam ON
`Beam OFF oo -
`Lamp
`Driving mode
`Town driving
`0-40km/h
`Country driving
`40-90km/h
`Motorway driving
`90km/h
`
`VB-L
`Main photometric axis control
`Main axis of lamps fixed 1.5° outward,
`respectively
`oo
`70
`30°
`Steering angle
`- - - -
`Main axis position 0° ........ 0° _ _ 5°
`oo
`50
`30°
`Steering angle
`- -
`50
`Main axis position 0° .. _ ...... 0°
`
`-
`
`40° _.... 100° ~ 180°-::::=>
`10° - - - - 20° ~ 60°
`
`Cutoff shape
`1 .....
`
`.,. 1.5dUP
`
`I
`I
`
`I
`+ 1.5illUP
`
`I
`I
`I
`+ 1.5dJUP
`
`I
`
`I
`
`MC-L
`
`LC-L
`
`CC-L
`
`0
`
`0
`
`0
`
`0
`
`0
`
`X
`
`0
`
`X
`
`X
`
`Fig. 3-6: Main-beam Stage Beam Control in Phase-I Front Lighting System
`
`459
`
`

`

`4.
`
`Evaluation of the Phase-I Front Lighting System
`
`The evaluation of the Koito Phase-I front lighting system was conducted on a
`test course situated on the foot of Mount Fuji, as shown in Figure 4. This two(cid:173)
`lane test course, 4 km long, contains bends, uphill and downhill slopes, T(cid:173)
`shaped crossroads, intersections, and a 800-meter long straight road section.
`Evaluation items and results are summarized in Table 4. A 10-point visibility
`evaluation scale was employed as follows:
`
`0
`
`2
`
`4
`
`6
`
`8
`
`Unacceptable
`
`Difficult to drive
`
`Not easy to drive
`
`Average driving ease
`
`Satisfactory driving ease
`
`10 Very comfortable driving
`
`Table 4: Evaluation of Phase-I Front Lighting System (8 Subjects)
`
`Evaluation item
`
`Driving ease at intersection &
`"T' crossroads
`Ease of cornering
`Ease ofhigh-speed driving on
`straight road
`Ease of driving on up-and-
`down slopes
`Ease of high-speed driving on
`straight road
`Ease of cornerinq
`
`Sub-beam
`stage
`
`Main-beam
`stage
`
`Conventional head-
`lamps
`(haloqen bulbs)
`4.1
`5.4
`6.1
`
`5.3
`
`6.1
`5.8
`
`Phase-I system
`
`7.9
`8.2
`
`7.6
`
`6.3
`
`6.5
`8.5
`
`The evaluation by eight subjects indicated a substantial improvement in night(cid:173)
`time driving ease by Phase-I as compared to conventional headlamp systems.
`A particularly remarkable improvement was reported in the visibility of various
`obstacles on intersections, T-shaped crossroads, bends and slopes. Further,
`the visibility of the lane shape from a distance and in a sharp cornering situation
`was found to have greatly improved. As the only exception, visibility during high(cid:173)
`speed driving in the main-beam stage improved minimally because, in all prob-
`
`460
`
`

`

`ability, the main-beam cut off position was set 1.5° above the sub-beam cutoff
`position.
`
`Remaining Problems and Countermeasures in Phase-I Front Light-
`5.
`ing System
`In the Phase-I front lighting system which is intended for demonstration driving
`in Japan and abroad, the driving modes are switched according to data from
`vehicle speed and steering sensors. Weather information is obtained from wiper
`operations (time and position). Consequently, Phase-I still has the following
`problems:
`(1) It is not possible to obtain full information on driving regions from vehicle
`speed and steering sensors.
`(2) Phase-l's sensors for collecting information on weather and road surface
`conditions are not adequate.
`
`To obtain more accurate information on driving regions, it is advantageous to
`use data from a GPS navigation system. Figure 5 shows a typical map available
`from a navigation system display in Japan. An arrow inside a circle indicates the
`current position of the vehicle. The numerous dots indicate nodes. Data on the
`positions of the vehicle and nodes are available from the navigation system in
`terms of latitude and longitude. In addition, a map data base can supply detailed
`road information for each node, as shown in Table 5:
`
`Table 5: Summary of Road Information at Node Position
`
`Data item
`Node position
`No. of links
`
`Road configuration
`
`Content
`Indicated in latitude and longitude
`No. of roads linked with node
`Road type: highway, national road, etc.
`*
`Tunnel, median strip, etc.
`*
`No. of lanes, road width, etc.
`*
`
`461
`
`

`

`Fig. 5: A Map on Navigation System Display
`
`Utilizing these data, it is possible to determine each driving region. In order to
`apply these data to the control of headlamp beams, however, it is necessary
`that map data bases be standardized throughout the world.
`
`In controlling the headlamp beams, it is useftJI to have access to information on
`road surface conditions, such as the surface being dry, wet or submerged in
`water. It will also be useful to differentiate rainy from foggy weather. This cannot
`be done by analyzing wiper operations or applying a raindrop sensor.
`
`In Japan, some vehicles in the market are already equipped with a lane depar(cid:173)
`ture warning system and an adaptive cruise control system, both incorporating a
`CCD camera as an image sensor. If CCD cameras are put to use, it will become
`possible to analyze weather and road surface conditions from image data with
`phenomenally improved accuracy. The important prerequisite; however, is that
`these intelligent sensors will have to become less costly.
`
`Problems also stem from national differences in road and traffic conditions. For
`example, traffic density and roadside illumination on highways, country roads or
`city streets differ considerably from one nation to another. In trying to develop
`an AFS specification, experts of various nations will need to discuss issues
`arising from different infrastructures from one country to another.
`
`462
`
`

`

`6.
`
`Development of a Phase-II Front Lighting System
`
`The goal of Phase-I I headlamp
`system development is to real(cid:173)
`ize optimal automotive lighting
`which is friendly to both human
`vision and the "machine vision"
`currently under study and which
`responds precisely to changes
`in driving conditions and opera(cid:173)
`realize automated
`tions. To
`driving, the lanes and obstacles
`
`must
`
`For collision avoidance
`
`For adaptive driving (cruise)
`
`For lane keeping
`
`Weather:
`
`elaer
`
`Assumed speed
`
`120 km/h
`
`Rliimy
`
`90 km/h
`
`Fig. 6: Lane Detection Targets in Japan
`
`be recognized by machine vision. Figure 6 shows the lane detection targets in
`Japan's research project<7
`
`)_
`
`To reach the goal, we are studying not only the basic characteristics of road
`surfaces, lane markings, rains and fogs, but also invisible beams projected from
`lamps<8>. As in the EUREKA AFS Project, it will be necessary that the largest
`number of researchers from across the world contribute their knowledge and in(cid:173)
`sight to the development of future automotive lighting systems for ITS.
`
`7.
`
`Acknowledgement
`
`We would like to express our deepfelt gratitude to Prof. H.J. Schmidt-Clausen
`for giving us an opportunity to present this paper. We are also grateful to the
`AFS Project members for their support of Koito's participation in the project
`
`463
`
`

`

`8.
`
`References
`
`(1) S. Kobayashi, K. Takahashi and S. Yagi : Development of New Forward
`Lighting Systems with Controllable Beams., SAE Paper 970646 ('97).
`
`(2) S. Kobayashi and M. Hayakawa : Beam Controllable Headlighting Sys(cid:173)
`tems., SAE Paper 910829 ('91).
`
`(3) K. Wada, K. Miyazawa, H. Shibata and K. Takahashi : Steerable Forward
`Lighting System. SAE Paper 890682 ('89).
`
`(4) Anonymous: Intelligent Lighting Systems - Their History, Function, & Gen(cid:173)
`eral Direction of Development. - Japan has some unique characteristics
`that influence its on-road lighting requirements., P.19-24, No.10, Vol.106,
`Automotive Engineering, ('98).
`
`(5) H. Hogrefe and R. Neumann : Adaptive Light Pattern., SAE Paper 970644
`
`('97).
`
`(6) J. Damasky and W. Huhn : Variable Headlamp Beam Pattern - Lighting
`Requirements for Different Driving Situations., SAE Paper 970647 ('97).
`
`(7) S. Kobayashi, K. Shimazaki, A. Hujita and S. Tugawa: Evaluation of Lane
`Marking Detection with Machine Vision under Poor Visibility., Report
`No.3152, 5th World Congress Proceedings (CD Media),5th World Congress
`on Intelligent Transport Systems, Seoul, Korea ('98).
`
`(8) S. Kobayashi, S. Yagi and M. Komatsu : Measurement of Retroreflection
`from Road Surfaces and Lane Markings., SAE Paper 1991-01-1211 ('99).
`
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`