DARMSTADT
`UNIVERSITY OF
`TECHNOLOGY
`
`PROGRESS IN AUTOMOBILE LIGHTING
`
`Department of Lighting Technology
`September 28/29, 1999
`
`ER FOUNTAIN AT MATHILDENHOHE, DARMSTADT
`
`VWGoA EX1025
`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
`
`Das Werk ist urheberrechtlich geschGtzt. Die dadurch begrGndeten Rechte, insbesondere die der Ober(cid:173)
`setzung, des Nachdrucks, der Entnahrne von Abbildungen, der Funksendung, der Wiedergabe auf photo(cid:173)
`mechanischem oder ahnlichem Wege und der Speicherung in Datenverarbeitungsanlagen bleiben, auch
`bei nur auszugsweiser Verwertung, vorbehalten.
`
`Die Wiedergabe von Gebrauchsnarnen, Handelsnarnen, Warenbezeichnungen usw. in diesern Werk
`berechtigt auch ohne besondere Kennzeichnung nicht zu der Annahme, daB solche Namen in Sinne der
`Warenzeichen- ·und Markenschutz-Gesetzgebung als frei zu betrachten waren und daher von jedermann
`benutzt werden d0rften.
`
`Copyright © 1999 Herbert Utz Verlag GmbH
`
`Druck: drucken + binden gmbh, Munchen
`
`Herbert Utz Verlag GmbH, Munchen
`Tel.: 089-277791-00
`Fax: 089-277791-01
`utz@utzverlag.com
`www.utzverlag.com
`
`

`

`Analysis of Eye-Movement Behaviour Using Moveable
`Headlamps
`
`Carsten Diem, H.-J. Schmidt-Clausen, Darmstadt University of Technology,
`
`Jan Lowenau, Jost Bernasch, BMW AG
`
`1. Introduction
`In the last few decades car headlamp systems have only slightly improved. The
`driver only has the choice between low and high beams and to switch on the
`fog lamps during adverse weather conditions. These systems are far more
`powerful than conventional light filaments replaced by halogen filaments and
`even more so now with gas discharge lamps have been introduced. Due to
`lenses, projection headlamps, and free-form reflector technology,
`special
`utilization of the light quantity has been increased by thirty to seventy percent.
`However, the headlamp system itself has remained essentially unchanged. The
`ability to direct the available light dynamically in the direction it is actually
`needed has remained only a wish. The question now is on which parts of the
`road the driver of a vehicle actually needs the light.
`Ninety percent of the information needed to drive a car is acquired by the
`driver's eyes. But up to now it is not fully understood which information the
`in the
`information
`driver really needs and also, where he will find this
`environment.
`Many papers quote the fixation behaviour and fixation distances of a car driver
`during the hours of daylight [1, 2, 5]. Regarding eye-movement behaviour at
`night, however, only a few investigations have been taken [1, 4]. Until now very
`little is known about the eye-movement behaviour in bends after dark [11 ].
`The Department of Lighting Technology at Darmstadt University of Technology
`and the Research Department of BMW AG therefore commenced a research
`project to obtain more information and details about the fixation behaviour of
`car drivers at day and night.
`
`185
`
`

`

`One requirement of the research project was to find out if and in which range it
`is possible to measure and quantify the influence on the fixation behaviour of a
`car driver if moveable headlamps are used. A second point was to establish the
`differences in eye-movement behaviour when using different light sources
`(halogen filament lamp (HFL) / gas discharge lamp (GDL)).
`
`2. Moveable Headlamp Systems
`A BMW E38 (7 series) was used as the test car. The car was equipped with a
`the moveable
`for
`Dornier Eye-Tracking-System and a control system
`headlamps.
`The newly developed moveable headlamps are controlled by path prediction
`based on the vehicle's dynamics and navigation data [7, 8, 9]. Using the output
`the moveable
`is possible to control
`it
`the path prediction model,
`from
`headlamps appropriately.
`is
`Figure 1 shows the path prediction structure. Prediction of the path
`estimating the lateral disturbances or accelerations acting on the vehicle body.
`A prediction of the future path of the vehicle based on the current vehicle
`dynamic is obtained in combination with a simple model of the vehicle. A filter
`has been added so that the variations in the prediction of the future path, e.g.
`due to steering wheel motions, can be kept under control.
`
`Vehicle Speed I.
`-
`.
`Yaw Rate
`-
`Steering Angle •
`
`Vehicle
`Sensor
`
`Disturbance
`Estimation
`
`Vehicle Soeed
`
`.
`-
`--
`Filtered Side Slip Velocitv
`Filtered Yaw Rate
`~ Corridor
`Lateral Disturbance Acceleratioo Prediction
`Filtered Steerina Wheel Annie ~
`
`~
`
`Figure 1: Dynamic corridor prediction structure
`
`The light distribution of series-production car headlamps were used as a basis
`for the construction of moveable headlamps. For the various investigations a
`
`186
`
`

`

`• headlamp with a halogen filament lamp H1 (HFL) and a
`• gas discharge headlamp (GDL)
`
`were used.
`
`The moveable headlamps were modified in such a way that the projection
`system was able to rotate horizontally with the help of servo motors. In this
`construction the whole reflector with the light distribution is moveable. The only
`small change in the light properties was an elliptical shaping of the outer lens in
`order to have enough space for the rotation of the projection lens ( see Figure
`2). The possible rotation angle of this moveable headlamp was s = ± 20°.
`
`Figure 2: Picture of the moveable headlamps used, equipped with a gas
`discharge lamp (GDL). The reflector is rotated as far as possible
`right (about & = 20°).
`Test - Conditions
`
`3.
`
`To measure the eye movement and the fixation behaviour of a driver under
`constant conditions, the investigations have been carried out on a standard test
`track. This standard test track is a circuit with a length of d = 8 km and with
`defined bends etc. One of the most important benefits is that on the test track
`there is no additional traffic (ahead, behind, oncom•ng), and therefore there is
`traffic. The
`no influence on the eye movement behaviour by additional
`
`187
`
`

`

`measurements were taken in good weather conditions.
`Ten test persons took part in this experiment. All of them had more than
`50,000 km driving experience and normal or corrected normal vision. During
`measurements on the test track the eye movement behaviour of the test
`persons varied according to the following five conditions:
`
`•
`
`•
`
`daylight
`night - time
`
`- without headlamps
`- with standard halogen headlamps (HFL)
`with moveable halogen headlamps (moveable HFL)
`- with standard gas discharge headlamps (GDL)
`- with moveable gas discharge headlamps (moveable GDL)
`
`the relative infrared cornea
`The Eye-Tracking-System (ETS) is based on
`reflexes. lt consists of two IR-illuminators (on the dashboard at left and right)
`which have different shapes. A module with a camera is installed directly in
`front of the driver to track his right eye. In front of the eye camera a mirror
`system is mounted which is adjustable in two axes. Based on an image
`processing, the mirror is moved so that the driver's right eye remains in the
`center of the eye camera. The fixation point is calculated from the relative
`position of the pupil and the IR-reflexes on the cornea. In addition to the eye(cid:173)
`camera, a so-called scene camera is mounted near the driver's head (height
`hE=1.17m).
`The calculated fixation position is displayed from the ETS on the scene video
`as a white cross and is recorded in a file form of x-y coordinates relative to the
`calibration points.
`By means of a special calibration process it is possible to convert the pixel
`coordinates to an angle of view direction (from the perspective view of the
`driver) and to a fixation distance.
`The width of the road lane was b = 3.75 m. The mounting height of the
`headlamps was hH = 0.65 m.
`
`188
`
`

`

`4. Eye Movement Behaviour
`
`The eye movement behaviour is recorded by the Eye Tracking System. In
`combination with the information about sections of the road, fixation behaviour
`at special parts on the test track is analyzed.
`
`Before the described experiments are conducted the ETS data had been
`evaluated on different road types (spatio-temporal) [2]. In this paper controlled
`investigations on straight roads, left-hand and right-hand bends are discussed,
`the radius of the bends is constant with r = 110 m.
`
`The representation of the fixation measurements when driving through part of a
`road is shown for example in Figure 3. In part a) the fixations are shown over
`the driving distance (bird's view presentation), in part b) the fixations are
`integrated over time and are displayed as one fixation area in the driving scene
`(perspective view).
`
`a)
`
`driver's line
`
`middle marking
`left road marking
`
`b)
`
`right road marking
`
`recorded fixation points
`
`Figure 3: Example of the fixation behaviour when driving on a straight road
`a) Bird's view presentation
`b) Perspective view of the driver
`
`189
`
`

`

`By integration over time the most frequently occured areas are identified. The
`x-y coordinates of the ETS are converted to angle coordinates (a, 13) with the
`origin at the position of the driver's head. This converted data is plotted in
`Figure 4. In this figure and in the following figures the single measurements are
`In
`standardized to compare the figures correctly (white 0%, black 100%).
`addition, the 90% and 50% fixation areas of the measurements are shown in
`the presented figures. To give an impression of the road geometry in the
`figures, the road markings are plotted as well as lines for different distances in
`front of the car. The point with a high frequency of fixation occurrences is called
`fixation accumulation point (FAP). The FAP is marked with two dotted lines
`(see Figure 4).
`To permit a statement about the spread of the eye movement in spatial terms,
`is defined. The area factor describes the relationship
`the area factor Afso
`between the complete field of vision for the driver (a= ±20°; -6° < J3 < 1 °) and
`the area which the driver used for 50% of the fixations (see Figure 4; 50%
`area).
`
`90% area
`
`50% area
`
`left road marking
`
`middle marking
`
`accumulation point
`
`distance
`
`hard shoulder
`
`driver's line
`right road marking
`
`-15
`
`-5
`-10
`O'.= -9,3
`number/%
`
`0
`
`5
`
`10
`
`15
`
`20
`O'. / 0
`
`100
`60
`80
`40
`20
`0
`Figure 4: Example of integrated fixation points of one driver for several trips
`of the same bend.
`
`190
`
`

`

`In every figure more than 3000 single measurements are plotted ( same person
`drove road part several times). The measurements shown in the following
`figures are all from the same test person.
`
`4.1 Daylight Driving
`
`The first experiment was driving on a straight two-line road with a hard
`shoulder at daylight without additional traffic and without changing conditions.
`The fixation accumulation point (FAP) distance is as far as possible (90-100
`meter). The small spread around the FAP can be easily recognized in Figure 5.
`
`13= -0,7
`
`-2
`
`~---+----;'--"---11-~~;--.......... '
`
`=
`
`·
`
`0 a--;---.-'"!'---;-...... -~""!--;..-!---~---"'i'i~~-,--..;.--~-...--;~--.....-t
`.~ .). j = • • • J J
`r .. , . r.· ( · I ·.·.:-···1-
`_
`l.1q_:_om:_-
`~-
`i
`·-fl-St~i- 1
`.=
`;·. ,
`j I '
`4 orh
`i t·· l + 1 ++++;' ++ + ,; ls,1;] 1J
`
`;
`
`-4
`
`'
`-+---
`
`-6-----------------1----------...... -------
`
`--:-5
`
`10
`
`15
`
`20
`al 0
`
`5
`0
`a= 2,2
`Fixation area when driving on a straight road at daylight.
`f3 = -0. 7°
`a = 2. 2°
`Fixation direction:
`FOAP 1
`d = 95.8 m
`:
`Arso = 0.10
`Area factor:
`
`-20
`
`-15
`
`-10
`
`Figure 5:
`
`1 FDAP: Fixation Distance Accumulation Point
`
`191
`
`

`

`Eye movement behaviour changes considerably when a driver approaches a
`bend. The driver begins to receive information from the course of the road in
`the bend (e.g. benq_ radius).
`In the bend the driver appears to obtain information about the course of the
`road from the tangent of the inside radius and the outside edge of the road.
`left-hand bend is at
`The fixation distance accumulation point (FDAP) for a
`d = 34.6 m (see Figure 6) and for a right-hand bend at d = 38.2 m (see Figure
`7). Figure 6 and Figure 7 show also, that the driver is scanning the road for an
`optimal lane keeping. For the left-hand bend the FAP is on the center of the
`road, for the right-hand bend the FAP is on the right-hand side.
`
`i ·.
`o.-.~-~-r-'""""!'-'!--\-~-!--' ........... - - - - ! -..... ~ ~ - ; -...... -!"'__,, _ _,_.....,.
`::.
`
`~= -2, 0
`
`Figure 6:
`
`a= -14, 1
`Fixation area when driving through a left-hand bend at
`daylight.
`Bend radius
`Fixation direction:
`FDAP:
`Area factor:
`
`r = 110 m
`a=-14.1°
`d = 34.6 m
`A,so = 0.81
`
`/J=-2.0°
`
`a/ o
`
`192
`
`

`

`13 / 0
`
`0 1-+-----------------~--t-----.---,.-__ .... _ ---~~---~
`
`·:
`
`:
`
`i--
`
`.·
`
`!3=-1,8
`-2
`
`-4
`
`-0------------------------------
`
`5
`
`20
`al 0
`
`15
`10
`a= 13, o
`Fixation area when driving through a right-hand bend at
`daylight.
`Bend radius
`Fixation direction:
`FOAP:
`Area factor:
`
`0
`
`-15
`
`-10
`
`-5
`
`0
`
`-
`
`Figure 7:
`
`r = 110 m
`a= 13.0°
`d = 38.2 m
`A,so = 0. 71
`
`/J=-1.8°
`
`4.2 Night-Driving - Standard Headlamps
`
`4.2.1 Halogen Headlamps at Night
`At night the eye-movement behaviour of the driver changes considerably due to
`the reduction of the accompanying information. This is one of the reasons for
`the reduction of the FDAP on straight roads by about fifty percent to a distance
`of d = 47.9 m. The position of the accumulation point is, as expected, only in a
`short distance in front of the cut-off-line of the headlamps on the road.
`
`193
`
`

`

`13= -1,4
`-2
`
`-4
`
`·=
`
`: ~:;:;=-:
`f:
`"
`I j
`·· i .... ·····t ······!······ · ·; ······;'··I · · --·- · ········!··~ ••··. · : ········--.i-...... ·.··························· ··························"
`l , i
`
`:.
`
`:
`
`-6...._, _________________________ ....i, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ......,
`20
`15
`10
`5
`0
`-5
`a/ o
`a= 2,4
`
`-20
`
`-15
`
`-10
`
`Figure 8:
`
`Fixation area when driving on a straight road at night.
`Headlamp system: standard halogen low beam (HFL)
`fJ = -1.4°
`Fixation direction: a= 2.4°
`d = 47.9 m
`FOAP:
`A,so = 0.14
`Area factor:
`
`Two effects could be described, when driving with standard halogen headlamps
`(ECE) through bends. The reduction of the illuminance on the road results in a
`reduced distance between the car and FAP (see Figure 9, d = 23.6 m). Another
`effect is the increased spread of the fixations. The driver collects more
`information for lane keeping, this is shown in Figure 9.
`
`194
`
`

`

`f3 / 0
`
`I
`0---------------------------
`
`-5
`
`0
`
`5
`
`10
`
`15
`
`20
`a/o
`
`-2
`
`J3=-2,9
`
`-4
`
`Figure 9:
`
`-10
`-15
`a= -11,9
`Fixation area when driving through a left-hand bend at night.
`The reduction of the perceptable environment leads to an
`increase of the field of interest (two FAPs left and right),
`which are in less distances.
`Headlamp system: standard halogen low beam (HFL)
`r = 110 m
`Bend radius
`Fixation direction: a= -11.9°
`d = 23.6 m
`FOAP:
`Arso = 0.88
`Area factor:
`
`f3 = -2.9°
`
`The fixation behaviour In right-hand bends at night with standard halogen
`headlamps (HFL) has the same characteristics as for left-hand and right-hand
`bends. Through the reduction of the visible surrounding the driver searches for
`the information about the road ahead in a fewer distance in front of the car. The
`the area factor changes from Atso = 0.14 to
`increases,
`field of fixations
`Af5o = 0.88. These are the reasons for two FAPs: one on the right-hand road
`border and the other at the left-hand road border (outside edge of the bend).
`Both F APs are at a distance of about d = 25.4 m. The figures show also, that
`the driver needs two fixation areas for lane keeping by using the standard
`halogen low beam system. The driver has to look on the right-hand and left(cid:173)
`hand side of the road to keep the lane.
`
`195
`
`

`

`f3 / 0
`
`-2
`~ = -2, 7
`
`-4
`
`-15
`
`-10
`
`20
`15
`10
`a/ 0
`a= 12, 3
`Figure 11: When driving through a right-hand bend at night-time with HFL
`there are two fixation areas (FAPs). The two fixation distances
`accumulation points (FOAPJ and the large areas of interest could
`·
`be seen very clearly.
`Headlamp system: standard halogen low beam (HFL)
`r = 110 m
`Bend radius
`/3 = -2. 7°
`a=-12.3°
`Fixation direction:
`d = 25.4 m
`FOAP:
`A,so = 0.64
`Area factor:
`
`-5
`
`0
`
`5
`
`4.2.2 Gas Discharge Headlamps at Night
`As already known, the luminous flux of GDLs is three times greater than the
`HFLs, also the light distribution is different from the halogen version. The area
`in front of the car is brighter, the light distribution is fundamentally more
`extensive and the brighter area in front of the car is responsible for a change of
`the contrasts on the road. Both
`level of the driver and
`the adaptation
`parameters have a considerable influence on eye-movement behaviour.
`
`196
`
`

`

`The eye-movement pattern when driving on a straight road with GDL is wider
`than with HFL and the FAP drifts to the driving line, which is the middle of the
`road (see Figure 11 ),
`
`o 11-'+-!""'-----l-~-,;--...;I ... ,, -"!'-·;-) ~---:1ir--.-.... <~= - ! - - " " ! - - - - - i - ~ - t - - -.....
`
`. ~..:_,=.!:,-1_:: . . t:: ,-.\,, ~·1:_ 1=c~~ , , .
`
`.
`
`,
`
`13=-1,0
`
`-2
`
`-4
`
`., ...... ) ........ L ...... l.. ..... ):: ...
`.
`:
`;
`
`.
`
`~
`
`5
`
`10
`
`15
`
`20
`0
`a.= o,o
`a/ o
`Figure 11: One fixation area when driving on a straight road at night with GDL.
`Headlamp system: gas discharge low beam (GOL)
`f3 = -1.0°
`Fixation direction: a= 0.0°
`d = 67 m
`FOAP:
`Arso = 0.22
`Area factor:
`
`-6----------------------------------
`
`-20
`
`-15
`
`-10
`
`-5
`
`197
`
`

`

`fl/ 0
`
`-2
`13= -2,2
`
`-4
`
`-6'-'-...... -----... _.___,j . . . . . _ _ . . . . . , _ . , _ _ . . . . . . . _ _ _ ....., _ _ _ _ _ _ _ _ . . . . . . . _ _ _ . . . . . . . . . . .
`20
`15
`10
`5
`0
`-5
`-10
`-15
`-20
`a/ 0
`a= -9,3
`Figure 12: One fixation area when driving through a left-hand bend at
`night with GDL.
`Headlamp system: gas discharge low beam (GDL)
`r = 110 m
`Bend radius
`/3 = -2.2°
`a= -9.3°
`Fixation direction:
`d = 30.9 m
`FDAP:
`Arso = 0.34
`Area factor:
`
`When measuring eye movement behaviour with GDLs in use, an increase of
`the fixation distance could be recognized. The FAP in left-hand bends is at the
`middle road marking (see Figure 12) and in right-hand bends at the right road
`marking (see Figure 13). FAP in both cases is on the bend tangent. It is
`important to notice that with GDL the driver has only one FAP, with HFL the
`driver has two F APs.
`
`198
`
`

`

`0 ~---..,;_--.-_.._ ..... ____ ,._. __ _..,_;--_-.-____ t ___ ""'!"""~-~----
`
`-4
`
`Figure 13:
`
`-15
`
`-10
`
`-5
`
`0
`
`5
`
`10
`
`20
`15
`a.I 0
`a= 14, 4
`One fixation area when driving through a right-hand bend at
`night with GOL.
`Headlamp system:
`Bend radius
`Fixation direction:
`FDAP:
`Area factor:
`
`gas discharge low beam (GOL)
`r = 110 m
`a= 14.4°
`d = 38.5 m
`A,so = 0.55
`
`/3 = -1.8°
`
`4.3 Night-time - Moveable Headlamps
`
`The light distribution of the headlamps used here is identical for driving with
`and without moveable headlamps on straight roads. Hence it is unnecessary to
`roads by using moveable
`show eye-movement behaviour on straight
`headlamps again.
`
`199
`
`

`

`4.3.1 Moveable Halogen Headlamps at Night
`Using moveable HFLs the fixations concentrate to the middle marking of the
`road and to the right-hand border of the road (see Figure 14 and Figure 15).
`There is only one FAP instead of the two FAPs measured with standard HFL.
`
`011...-----------------------+-------------...--~
`
`··1
`
`··
`
`- 2
`13= - 2 , 5
`
`- 4
`
`- 2 0
`
`-15
`
`i :
`i :
`i, :
`
`\
`\
`
`- 5
`-10
`<X= - 7 , 2
`
`-6-----------------------------------~ ..............
`Figure 14: One fixation area when driving through a left-hand bend at night
`with moveable HFL.
`Headlamp system: moveable HFL
`r = 110 m
`Bend radius
`f3 = -2.5°
`Fixation direction: a= -7.2°
`d = 27 m
`FDAP:
`A,so = 0.47
`Area factor:
`
`0
`
`5
`
`10
`
`15
`
`20
`a l o
`
`200
`
`

`

`(3 / 0
`
`-4
`
`20
`15
`10
`5
`0
`-5
`-10
`-15
`-20
`-6 - - - - - - - - - - - - - - - - - · - - - - - - - - - - - - -
`a/ 0
`a= 13,2
`
`Figure 15: One fixation area when driving through a right-hand bend at night
`with moveable HFL.
`moveable HFL
`Headlamp system:
`r = 110 m
`Bend radius
`a= 13.3°
`Fixation direction:
`d = 25.5 m
`FOAP:
`Area factor:
`Arso = 0.81
`
`/3 = -2. 7°
`
`4.3.2 Moveable Gas Discharge Headlamps at Night
`
`When using moveable GDLs the fixation distance accumulation point (FDAP)
`proved to increase to d = 35.8 m for the left-hand bends and to d = 43.5 m for
`right-hand bends. The distance values are slightly larger than the belonging
`daylight values (see Figure 16 and Figure 17).
`
`201
`
`

`

`13=-1,9
`
`···;-·-·····-·
`
`4
`
`-
`
`I 2am
`
`1
`
`1
`
`. 1_:i=t; =r_ =+_ ;:,it=+I ~\ti=+_ =f~~f~~ I i ! : I
`; I r i t H rl l i
`' , '· ; ·· ; : · i 1
`1 ! ! ! i
`1 r 1
`1 111 11\1
`· , 1
`1
`-6..._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
`1
`20
`15
`10
`5
`0
`a./ 0
`
`-20
`
`-15
`
`-5
`-10
`a.= - 9 , 3
`Figure 16: One fixation area when driving through a left-hand bend at night
`with moveable GOLs.
`Headlamp system: moveable gas discharge (GDL)
`r = 110 m
`Bend radius
`fJ = -1.9°
`a= -9.3°
`Fixation direction:
`d = 35.8 m
`FOAP:
`A,so = 0.41
`Area factor:
`
`In the analysis of the right-hand bend (see Figure 17), it is noticeable that the
`spread of the fixations (field of interest) increases again. One explanation could
`be that because of the available luminous flux in direction of driving, the driver
`has the ability to recognize the subsequent direction peripherally and can fixate
`other interesting objects in the road area. With other words the driver has more
`time for driving and the tiredness of the eyes could be reduced.
`
`202
`
`

`

`)3=-1,6
`-2
`
`-4
`
`-6----------------------------
`
`5
`
`10
`
`20
`15
`a= 15, 3 a./ 0
`
`-20
`
`-15
`
`-10
`
`-5
`
`0
`
`Figure 17: One fixation area when driving through a right-hand bend at night
`with moveable GDLs.
`Headlamp system: moveable gas discharge (GOL)
`r = 110 m
`Bend radius
`Fixation direction: a= 15.3°
`d = 43.5 m
`FDAP:
`Arso = 0.53
`Area factor:
`
`f3 = -1.6°
`
`5. Results and Conclusion
`
`5.1 Results
`
`In Table 1 and Figure 18 we compare the fixation distance accumulation points
`(FDAP). When driving with standard halogen filament lamps (HFL) there have
`been measured two fixation accumulation points (FAP), when driving with
`moveable HFLs this was reduced to only one FAP, which could also be noticed
`with standard gas discharge headlamps (GDLs).
`
`203
`
`

`

`The FAP is more distant when using moveable GDL compared to driving at day
`light
`the
`is generally known
`right-hand bends). As
`in
`(especially
`light
`distribution of GDLs illuminates farther than the HFLs. Therefore larger fixation
`the
`(HFL +GDL)
`distances are possible. By using moveable headlamps
`illumination is remarkable larger in driving direction when passing bends.
`
`fixation behaviour
`
`daylight
`
`night-time
`
`standard headlamp
`
`moveable headlamp
`
`light
`source
`
`road I bend
`
`a,/0
`
`fj/0
`
`dim Arsol1
`
`a,/0
`
`straight
`
`HFL
`
`2.2
`
`-0.7 95.8 0.10
`
`2.4
`
`13;0
`
`dim Arsol1
`
`a,/0
`
`13;0
`
`dim
`
`Arsol1
`
`-1.4 47.9 0.14 2.4
`
`-1.4 47.9
`
`0.14
`
`straight
`
`GDL
`
`2.2
`
`-0.7 95.8 0.10
`
`0.0
`
`-1.0
`
`67
`
`0.22 0.0
`
`-1.0
`
`67
`
`0.22
`
`left
`
`left
`
`HFL
`
`-14.1
`
`-2.0 34.6 0.81
`
`-11.9
`
`-2.9 23.6 0.88
`
`-7.2
`
`-2.5
`
`27
`
`0.47
`
`GDL
`
`-14.1
`
`-2.0 34.6 0.81
`
`-9.3
`
`-2.2 30.9 0.34
`
`-9.3
`
`-1.9 35.8
`
`0.41
`
`right
`
`HFL
`
`13.0
`
`-1.8 38.2 0.71
`
`-12.3
`
`-2.7 25.4 0.64 13.3
`
`-2.7 25.5
`
`0.81
`
`right
`Table 1:
`
`-1.6 43.5
`-2.8 38.5 0.55 15.3
`-1.8 38.2 0.71 14.4
`GDL 13.0
`Results of the fixation behaviour of the Figure 4 to Figure 17
`HFL: Halogen filament lamp
`GDL: Gas discharge lamp
`
`0.53
`
`Important is to point out that mov~able HFLs do not achieve a FDAP as distant
`as the FDAP of non-moveable GDLs. Also, observable is that the FDAP using
`moveable GDLs is larger than the FDAP when driving at daylight. This could be
`explained as follows: When driving at daylight the driver could use the
`peripheral vision and could acquire necessary information about the road
`geometry ahead using few fixations in a distance of 50-100 meters for bends.
`For the lane keeping in bend itself the drivers use fixations in a shorter range of
`about 35 meters ( 1-2 seconds ahead). But, when driving at night the driver has
`no information about the scenery ahead and, also, can use peripheral vision
`only very limited. The necessary information for orientation must be acquired
`
`204
`
`

`

`by foveal vision, i.e. using fixations. Therefore, by hav.ing the ability to fixate
`much farther with moveable GDLs the driver actually uses this to achieve
`information about the scenery ahead with fixations in a range of about 35-45
`meter_ To summarize, the FDAP during driving at daylight seems to be
`representative for fixations for lane keeping while the FDAP during night-time
`driving seems to be the main fixation point for orientation.
`b/m
`
`light distribution (standard GDL)
`
`-10
`
`·•···•···
`
`... ~-···
`
`·····---···········-····· ...... /
`
`\
`
`'ll!'.
`------
`---..,.,,.~
`
`.......
`
`,.
`........... ,........
`"··;;,:,~····,..
`"'-<''····-· .... , ..... , .... --..... ,--····.-·:~"<:··-':,.,·.·~-<··············~
`
`'--- - , .
`............... ~
`'
`...,_).
`
`•··• ..•
`....... =--····
`
`-~ -. "~-.. --- ~, .................. ...
`
`.
`
`0
`
`10
`
`20
`
`30
`
`40
`
`~ " ' ' , , , ~ ~ ~ , ~ - , ~ - , , ,
`' ........... __
`' '
`'·,,
`~..., ' ~ .
`
`................ _
`
`-------..... , ___ .~_,...,--- --
`
`light distribution (moveable GDL)
`
`"'\',, '\
`"·, \
`
`\,
`
`....
`
`0
`
`10 20 30 40 50 60 70 80 90 · 100
`dim
`Figure 18: Fixation distance accumulation points (FOAP) for different
`headlamp systems and different road parts.
`daylight
`Accumulation points: X:
`standard halogen
`0:
`•: moveable halogen
`+:
`standard gas discharge
`D: moveable gas discharge
`
`5.2 Conclusion
`
`In this paper experiments concerning the analysis of the eye-movement be(cid:173)
`haviour for 4 different headlamps conditions are presented. First results with
`moveaqle headlamps show clearly the advantage of moveable GDLs over
`static GDLs as well as over moveable HFLs.
`205
`
`

`

`In addition, the use of moveable GDLs shows no negative effect on driving
`the subjective advantage of
`behaviour. The experiments demonstrated
`moveable GDLs for the driver. The moveable GDLs seem to serve as an active
`guidance device for the driver by means of lighting up the scenery primarily in
`driving direction.
`
`the
`
`focus will be on experiments concerning
`the near
`characterization of FDAPs at daylight and night-time driving with different
`dynamic light patterns for moveable GDLs.
`
`In
`
`future
`
`the
`
`6. Literature
`
`[1]
`
`[2]
`
`[3]
`
`[4]
`
`(5]
`
`Albrecht, R.; e. a.
`Sicht aus Kraftfahrzeugen - Literaturstudie - Einflui?> eingefarbter
`Scheiben bei Dunkelheit
`Forschungsprojek.t 7717; BAST, Bergisch Gladbach 1979
`Bengler, K.; Bernasch, J. H.; Lowenau, J.P.
`Comparison of Eye Movement Behaviour during Negotiation of Curves
`on Test Track and in BMW Driving Simulator
`Annual Meeting of the Europe Chapter of the Human Factors and
`Ergonomics Society,
`Groningen, The Netherlands 7. - 8. Nov. 1996
`Biehl, B.
`Probleme bei der apparativen Messung der Blickbewegungen in
`konkreten Verkehrssituationen
`Universitat Mannheim, Mannheim 1980
`Cohen, A S.; Studach, H.
`Eye Movements while driving Cars around Curves
`Perceptual and Motor Skills. No. 44, pp 683-689, 1977
`Cohen, A. S.
`Augenbewegungen des Autofahrers beim Vorbeifahren an
`unvorhersehbaren Hindernissen und auf freier Strecke
`Zeitschrift fur Verkehrssicherheit 22, No. 12, pp 68-76, 1976
`
`206
`
`

`

`[6]
`
`[7]
`
`[8]
`
`Land, M.F.; Lee, D.N.
`Where do we Look when we Steer
`Nature, 369, pp. 742-744, 1994
`
`L6wenau, J.P.; Bernasch, J.H.; e. a.
`Adaptive Light Control - A new Light Concept - Controlled by Vehicle
`Dynamics and Navigation
`SAE paper 980007, Detroit, Michigan 1998
`
`MOiier, H.; Lowenau, J.; Bernasch, J.
`Adaptive Light Control (ALC) - Using Real-time Light Simulation for the.
`Development of Movable Headlamps
`Symposium Progress in Automobile Lighting, Darmstadt University of
`Technology, Darmstadt 1997
`
`[9]
`
`Reich, F. M.; Bernasch, J.H.; Lowenau, J.P.
`Online Steering Dynamics in the BMW Driving Simulator
`IMAGE Conference, Scottsdale, Arizona, USA 1996
`
`[1 0] Schmidt-Clausen, H.-J.; Rosenhahn, E.-O.; Dietz, S.
`Criteria for the Visibility of Road Markings
`Darmstadt University of Technology, Darmstadt 1998
`
`[11] Zwahlen, H.T.
`Driver Eye Scanning Behaviour on Straight Roads and on Curves at
`Night
`In Fourth European Congress on Eye Movements, pp. 169-171,
`Gottingen 1987
`
`[12] Zwahlen, H. T.
`Eye Scanning Rules for Drivers - How Do They Compare with Actual
`Observed Eye Scanning Behavior
`Transportation Research Records 1403, Athens, Ohio, USA 1992
`
`207
`
`