DARMSTADT
`UNIVERSITY OF
`TECHNOLOGY
`
`PROGRESS IN AUTOMOBILE LIGHTING
`
`Department of Lighting Technology
`September 28/29, 1999
`
`FOUNTAIN AT MATHILDENHOHE, DARMSTADT
`
`VWGoA EX1028
`U.S. Patent No. 11,208,029
`
`

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`dedicated to
`
`Mr. Reinhard Ropke
`
`

`

`28 I 29 September, 1999
`
`Proceedings of the Conference
`
`Lichttechnik Darmstadt
`
`Published by
`
`Prof. Dr.-lng. H.-J. Schmidt-Clausen
`Darmstadt University of Technology
`
`Eigentum der
`AUDIAG
`D-85045 lngolst.R..-,1,
`
`UTZ
`Herbert Utz Verlag - Wissenschaft
`Mi..inchen 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. 6. PAL '99 : 28./29. September, 1999 ; proceedings of the conference/
`Lichttechnik Darmstadt. - 1999
`ISBN 3-89675-920-5
`
`Das Werk ist urheberrechtlk:h geschutzt. Die dadurch begrundeten Rechte, insbesondere die der Ober(cid:173)
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`
`Copyright © 1999 Herbert Utz Verlag GmbH
`
`Druck: drucken + binden gmbh, Munchen
`
`Herbert Utz Verlag GmbH, Munchen
`Tel.: 089-277791-00
`Fax: 089-277791-0.1
`utz@utzverlag.com
`www.utzverlag.com
`
`

`

`Adaptive Frontlighting - Experimental System
`Development and Functional Evaluation
`
`Bernhard Worner
`
`Automotive Lighting
`
`Background
`The driver's comfort and safety can be improved considerably by adaptive
`
`motor vehicle headlighting, with the today's technical means in lighting design
`
`and manufacturing, as well as sensors and communication systems in cars. The
`
`actual requirements for frontlighting devices, being established decades ago, do
`
`not permit for such variable devices. Therefore, within the frame of the Eureka
`project AFs 1> the European car and headlighting manufacturers studied the
`· possible specifications for such. advanced requirements with the goal to submit
`
`a proposal for a draft Regulations.
`
`Within this project studies for adaptive headlighting requirements, practical tests
`
`with such variable headlighting devices had to be performed on the road and
`
`under real ambient and traffic conditions, as a sound base of experiences for
`
`the definitions - besides theory and laboratory investigations.
`
`Mainly for this purpose Automotive Lighting developed an experimental system
`
`of variable· headlamps. It's design, the device capabilities, the experiences and
`
`conclusions gained up to now with this system shall be discussed here.
`
`Experimental System Design
`
`The first goal was to realize an as large as possible span of passing lighting
`
`variations and transitions between the different states,
`
`including possible
`
`limiting values of luminous intensities. A boundary condition was the integration
`of the experimental devices
`in a realistic size of construction as for a
`· conventional headlamps, and full ability for road testing use.
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`844
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`These considerations were made in close cooperation with Daimler-Chrysler
`lighting experts. The vehicle for the design base and road tests was chosen a
`Mercedes S-Class car (W140).
`
`The main functional targets were the adaptive passing lighting a) for general
`purpose as e.g. country road, b) for town conditions and, as the most challeng(cid:173)
`ing task, c) for adverse weather conditions.
`
`The design of the adaptive country road passing lighting is derived and followed
`up directly from different road geometry, vehicle speed and drivers need: on
`straight roads and at higher speed a rather narrow patte'rn but a long reach is
`needed; for bended roads and at lower speed wide lighting is necessary and a
`combination of both is adequate on roads with more than two lanes often.
`
`Realizing well the former discussions in Europe of a dimmed passing lighting, to
`be applied in towns for optimum use of the public lighting, a spectrum of such
`patterns was created for studies of this matter, including the conspicuity
`question and optimized wide illumination for crossings and when passing
`parked cars.
`
`The interaction to the opposing traffic is quite different in the case of the adap(cid:173)
`tive passing lighting for wet road conditions, - a situation which in our regions is
`from the visibility
`the far most frequent form of adverse weather and which -
`is feared by the drivers, even young drivers, or well experienced
`point of view -
`
`ones.
`
`The reasons behind this difficult situation shall be pointed out here briefly: the
`most relevant factor is the changed scattering of light at the road surface,
`caused by the increasing filling up of the roughness recesses of the road pave(cid:173)
`ment with water, during rainfall; as a consequence the back scattering is re(cid:173)
`duced: the driver does not any more see whether and where his headlamps
`bring light on the road; the light is instead - due to the higher degree of specular
`rather guided to the trees, but also to the the opposing traffic. In
`reflection -
`case of a plane and inundated road, this leads for the opposer to the visual
`impression as to oppose two pairs of headlamps, one of them above the road
`,
`and a second below the road. The luminance intensities emitted from the latter
`are far higher than that of the first one, leading to illuminations at the eye much
`
`.
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`.
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`'•
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`845
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`higher than that coming directly from the headlamps. If the road is somewhat
`wavy, even more than one such disturbing pairs of reflex centres can occur.
`
`The draft of the adaptive passing lighting investigated here for the described ad(cid:173)
`verse weather situation is as follows: those areas of the road surface where the
`opposing situation relevant r:_eflexes are generated, shall be illuminated less;
`they are anyhow rather close to the vehicle (below 25 m when a critical distance
`of some 50 or 60 m is supposed). This does not interfer with recognition of a
`possible obstacle on the road: it can be realized at a much greater distance;
`· whereas, if a laterally moving subject will be made visible by the side illu(cid:173)
`minations. Therefore, to the drivers benefit, a more intensive illumination is di(cid:173)
`rected to the left curb as well as to the zones directly below the horizon and,
`especially, to the right curb of the road, being supported by a somewhat higher
`adjustment of the lamps than for conventional passing lighting, e.g. to H-0.3%.
`
`This lighting draft had led in proving ground tests to significant positive judge(cid:173)
`ments of both, drivers and opposers. We expect here a real gain in safety re(cid:173)
`lated aspects in addition to the drivers comfort improvement.
`
`Optical Elements Design and Capabilities
`
`The Headlamp system is built up of each three optical elements or units per
`side of the vehicle, as shown in fig.1.
`
`The "basic module" is a modified ellipsoidal lamp with 70 mm lens, equipped
`with a 65W halogen bulb. The light distribution is fixed but the luminous flux can
`be changed in three steps, starting from a standard Emax of some 25 Ix, it can be
`pushed to 45 Ix, or dimmed to 17 Ix. The booster stage is intended for shorttime
`operation, the lower, economizing stage is thought for the town application.
`
`The cut off is controlled by a multifunctional shielding device. It can be set in
`two fixed stages at the right hand side ofV-V, corresponding to a horizontal cut
`off line there, limiting the well known 15 degrees asymmetric slope either 0.3°
`or 1.2° above the left side horizontal cut off. And, it can be further set quasi
`continuously to fully open aperture. The latter can allow for a) providing a main
`beam lighting, orb) for control of the cut off as an alternative to the levelling de(cid:173)
`ideally for a dynamic cut off control with
`vice with very low mass movement -
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`846
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`high wearing resistance. In combination with the levelling, the variable shielding
`can also allow c) for a lower aimed beam with maintained cut off position.
`
`Whereas the zone Ill control is performed by the rather fast "cut off machine"
`(some 1/10 of a second reaction time), the lower foreground zone control is
`achieved by an additional shield, moved slowly (2 seconds for full range) and ·
`can be activated right and left separately to an arbitrary state. It is foreseen for
`performance of the adverse weather passing lighting in case of road wetness
`being signalized.
`
`Fig.1:
`
`Experimental headlamp system devices with optical modules pro(cid:173)
`viding basic passing lighting (1 ), side illuminations to left side (2) and
`right side (3), wide band spot (4), narrow spot (5), position lighting (6),
`main beam lighting (7), direction indicator (8); devices for aiming &
`adjustment (A), and cut off modification (c).
`
`The "side illumination modules" for the right and left side consist of a second
`pair of halogen ellipsoidal lamps, yet with very small construction dimensions in
`length and lens diameter, being designed illuminate the curbes intensively on a
`distance of some 25 meters. The illumination lateral extension (1 Ix) is about
`50° each, and the Emax is some 20 Ix. The cut off is a pure horizontal. In the right
`headlamp this module's axis is directed by some 20° to the right, in the left
`headlamp it is some 25° to the left.
`
`So, this lamp element provides not only a good jllumination of the curb (respec(cid:173)
`tively adjacent areas) as desired for the adaptive adverse ,weather passing
`lighting. Moreover, due to it's light volume and a reach of some 40 meters it is
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`capable for good illumination in bended road situations too, or, when turning off,
`in town areas, and it may serve for a fog light.
`
`The modules were provided to be horizontally turnable, but the illumination
`width is large enough so that this was not deemed necessary.
`
`The two "spot modules" are specially designed on base of wide reflection type
`halogen lamps (210 x 55 mm) and are equipped with H7 bulbs. They provide
`two different kinds of punctually enhanced illumination: the element in the right
`hand side headlamp emits an asymmetric spot of some 6 x 2 degrees with a cut
`off to the left and upwards. It's max intensity, close to the left upper edge
`roughly at 75R provides some 180 Ix (once for the system, so corresponding to
`90 Ix per vehicle side), but the value in HV is only a fraction of one Ix. It can il(cid:173)
`luminate perfectly the right curb on a straight road. But even in wide right hand
`bends it fits well and can be used since it's upper cut off is always below the
`critical directions for oncomers eyes or rear mirror positions.
`
`The corresponding unit at the left side of the car provides a band of light, 1.4°
`high and 25° wide, with a very constant illumination of some 5 Ix. It supports the
`reach without contribution to th.e foreground; additionally a much wider reach
`zone is created compared to the standard lamps. The effect is not that obvious
`as that from the right side spot, but, nevertheless useful enough for the compo(cid:173)
`sition of the desired spectrum of light patterns.
`
`Adjustment
`
`All of the above lamp elements are contributing to the passing lighting and have
`a horizontal cut off. For variable vertical adjustment they were equipped with a
`dynamic levelling device, acting to the whole cluster of lamp elements. This de(cid:173)
`vice allows for right and left side separate preset adjustment changes when
`necessary for the adaptive illumination task.
`
`Lighting Functional Performance
`
`The system allows for a lot of different beam patterns by activation of the ten
`independent control switches available on the manual operation board.
`
`848
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`The following patterns were most used during the tests: starting from the stan(cid:173)
`dard passing lighting (fig. 2a) two different stages of the adaptive passing
`lighting for adverse weather/ wet road conditions are shown in (fig. 2b and 2c).
`
`The adverse weather lighting stage 1, as designed for a damp road, shows the
`required lower foreground illumination and the much stronger illumination of a
`very wide and longer range when compared to the standard distribution. The
`
`I
`reduc~d
`foregii, und
`illumin tion
`
`Fig.2: Experimental headlamp system adaptive passing lighting; vertical illumi(cid:173)
`nance (at 12V) on the ground; grey key steps, in Ix: >1; '7>4; >10; >30;
`>80; a) standard pattern (basic modules only) b) adverse weather
`lighting stage 1, for damp road and c) stage 2, for wet road
`
`849
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`secono stage of the adverse weather lighting - designed for conditions of a
`rather wet road - has the same characteristics yet even more intensively
`performed either.
`
`Fig.3 shows some of the numerous possibilities of the experimental adaptive
`lighting for dry conditions: the"beam can be made wider in two steps when
`
`I 3a
`
`Fig.3: Experimental headlamp system adaptive passing lighting; vertical illumi(cid:173)
`nance on the ground; a) wide illumination for country road with bends,
`b) Jong reaching illumination for main country roads and c) higher
`aimed lighting for motorway situations
`
`850
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`adding the left side "wide spot" and the side illuminations (fig 3a); it can get a
`longer range with unchanged beam width when boosted and added the right
`side spot (fig 3b). When in addition higher adjusted, this latter beam may also
`serve as a good passing lighting for motorway situations(fig 3c); here the. re(cid:173)
`duced cut off step is applied for avoiding of dazzle in rear mirrors, despite the
`rather high adjustment to H-H. When the wide distribution is applied to one side
`
`4a
`
`4c
`
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`
`Fig.4:
`
`Experimental headlamp system adaptive passing lighting for town
`areas; vertical illuminance on the ground; a) standard illumination
`dimmed and with reduced asymmetry, b) widespread illumination only
`and c) with wide spot added
`
`851
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`

`

`only, it can serve well for adaptive lighting in bending road situations too; for
`curves with a larger radius an additional higher adjustment plus the reduced
`sector application provides a good visual range there.
`
`For application in town conditons, characterized by lower speed and public
`lighting; the conventional light'-distribution can be dimmed and reduced in the
`symmetric part (fig 4a), or, depending on speed and ambient light conditions a
`very wide illumination only can be chosen which do not interfer with the
`contrast, provided by the public illumination (fig 4b and c).
`
`System Performance Evaluation and Experiences
`
`The system was tested on proving grounds too, but extensively and mainly in
`more than six months test use on public roads of all kinds. Here it payed out
`that with this system all types of variable passing lighting could be performed as
`discussed. The functional changes at this time were operated manually by a
`second person in the test car. This resulted in an interesting and very effective
`learning process about possible switching criteria and threshold availability or
`combinations. So, e.g. the public lighting levels for town-adapted passing
`lighting and the correlation of wiper operation to reflex glare conditions oh the
`road were figured out.
`
`The functional units "boosting", "side illuminations", "spot lightings", "vertical
`preset adjustment capability" and last not least the upper and lower "cut off ma(cid:173)
`chine" were found to be all very useful even when the frequency of use, ac(cid:173)
`cording to the local and ambient or traffic situation differed considerably.
`
`The higher adjusted and boosted light patterns for adverse weather and motor(cid:173)
`way situation were mostly used with the reduced right side cut off step; the
`adjustment optimum was found at some 0.4 degrees above standard aiming;
`higher aiming reduced the positive effects. Boosted lighting and spot were
`favorites too on main country roads; the strong side lighting was applied
`frequently on country roads of lower categories but also as bending and very
`wide road lighting support. Dimmed lighting for public lit areas was applied for
`to be fully sufficient, and the
`It was found
`experimental purpose only.
`conspicuity to other traffic participants was felt quite good, especially with the
`
`852
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`pair of small ellipsoidal H7 lamps (side illuminations) used. Finally, the missing
`foreground illumination of the adverse weather passing lighting was in no case
`a problem; on wet roads anyhow; on dry roads it was well realized, but, the
`drivers visual task was not affected even then.
`
`All passing lighting performances. as provided and tested were very useful!; and
`the opposers - in arranged meeting situation conditions - did not complain. Zone
`Ill -changes due to additional lamps, being switched on or off, did not bother the
`opposer in a single test case. This was found despite provocating frequent ·
`changes in some tests. The asymmetric appearence of the car, as caused by
`any switched off lamp modules on one side only; if not needed for a specified
`function, had no disturbing effect.
`
`Conclusions
`
`The goal of the experimental system was fully reached. It could be shown that
`for the passing · lighting modes as well as . their
`lighting -principles
`the
`combinations - despite being not performed that perfectly in all details as it
`would be done with serial products - have a very high acceptance from drivers
`as well as from opposers side. Even the famous additional 2 x 90 Ix right side
`spot did not lead to a problem or complaints. This means, that the !imitating
`values as choosen for illumination · tevels as well as for adjustment positions
`seem to be well tolerable. The rule "more light - more shadow" (in this case:
`more dazzel) do not apply here if the adaptive passing lighting design strategy
`a strategy, which, among other
`is followed -
`tested
`as described and
`informations and data, may contribute to a base for the future approval scheme
`of such systems as to be proposed.
`
`Acknowledment
`
`Daimler Chrysler AG provided not only the test vehicle and realized the switch(cid:173)
`ing devices, but contributed considerably to system development and gaining
`the test experiences.
`
`1) Eureka Project EU1403 Advanced Frontlighting Systems (AFS)
`
`853
`
`