C OVER STORYLighting Technolo gy

Additional Safety throughHeadlight Projections
Until now, only head-up displays have been used to superimpose necessary information onto
the driver’s field of vision in such a way that the driver does not have to take his eyes off theroad. Ford has modified the headlight system so that information on navigation and traffic is­projected directly onto the road.

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W R ITTEN BY

Dipl.-Ing. Michael Koherr
is Research Engineer in the Advanced
Lighting Team, Automated Driving Europe,at the Research and Innovation Center ofFord Werke GmbH in Aachen (Germany).

g Particularly when driving in thedark, it is important to keep the driver’s
attention and gaze as far away as possible from what is happening in front of
the vehicle and the course of the road,due to the limited visibility comparedwith driving in daylight. Thanks tosteering headlamp systems or, more
recently, predictive steering and thus
directional headlamps, the center ofthe light beam is always on the roadahead of the vehicle. It now makes
sense to supplement the light, which
is optimally positioned on the vehicle’s
path, with additional information, thus
making the journey as effortless as­possible for the driver.

© FordHEADLIGHT PROJECTION

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02-03|2023   

The new LED headlight system could
take this a step further. In addition
to the conventional low beam andhigh beam, it has a pixel module thatcan display 30,000 pixels in a 100 ×300 matrix. The benefits include botha much improved and more accurate
glare-free high beam – as well as theopportunity to project warnings andinformation using a wide variety of­symbols, graphics, or even dynamic
film clips. Currently, the module canbe tilted vertically to be active either
in the high beam area or in the apron
area. In this way, a greatly improved
and more accurate glare-free high beamor, tilted downwards, corresponding­projections with various information
can be realized in the apron.
The display of graphics requires additional effort to the conventional LED
headlamp, since image sequences must
be both processed and transmitted. Until
now, control was limited to a given light
distribution. which, for example, waspartially switched off for glare-free highbeam. The number of channels thathave to be controlled in the pixel headlight has multiplied, and the represen­tations have become more complex.
The interfaces must be adapted tothis amount of data.
INFORMATION OVERLOAD

With modern vehicles, the amount of
information a driver is provided withhas increased dramatically. In theearly days, this was easily displayedon the instrument cluster behind thesteering wheel. This is easily visible
with only a small angular deflectionof the eyes, so that the driver can­easily implement the motto “Eyes on
the road, hands on the wheel”. The­infor­mation was limited to the content­necessary for driving a vehicle, suchas speed, rpm, warning and status­displays and the like.
The radio, or today multimedia
devices and similar equipment, multiply the amount of information offeredand it is up to the driver to pay attention to it depending on its relevance.
With the display arrangements­common today and the abundance ofinformation, among other things for­navigation, the time spent looking andsearching for the relevant displays is­relevant. In the 1 to 2 s necessary for
this, one covers up to 50 m at speeds
common on country roads. Thus, any
possibility of making the information­relevant to the driving task directly
accessible to the driver without him­having to take his eyes off the road ishelpful. Thus, a display and localizationthat minimizes or even eliminates thistime of inattention is preferable.
LOCATION-CORRECTDISPLAY OF DRIVING-RELEVANT
INFORMATION

Until now, the only way to support
this has been to superimpose necessary
information into the driver’s field ofvision with a head-up display without
requiring the driver to take his or hereyes off the road. The information floats
above the road ahead, only seemingly
creating the impression that the information is in the path of travel. With the­latest headlamp technology, it is now
possible to write information directly
onto the road.

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C OVER STORYLighting Technolo gy

PROJECTION HEADLIGHTS

LED technology basically allows
great freedom in the design of the­headlamp. There are virtually no limits
here in terms of shape and size. Further
development of LED with stronger andmore efficient chips has opened up thepossibility of glare-free high beams
after replacing the conventional low
beam and high beam function with­horizontal segmentation of the highbeam, or matrix high beam; Further
development now leads to the pixel
headlamp. With sufficiently high­resolution both horizontally and­vertically, symbols and images can
now be displayed in their entirety.

FIGURE 1 Ice and snow warning (© Ford)

REPRESENTATIONS

By adjusting the pixel module vertically, pictograms can be projected
onto the road ahead of the vehicle.
These can be warnings detected by thevehicle’s sensor system, such as warnings of ice or slippery snow, FIGURE 1.
Another ­possibility would be turn-byturn ­directions from the navigation system, ­F IGURE 2, or indications of traffic
signs recorded by the vehicle’s camera.
Speed limits are currently probably themost frequently perceived signs fromthe v­ ehicle with the usual display inthe instrument cluster. Displaying themon the road in front of the automobile
keeps the driver’s eyes on the roadand the information constantly­present, FIGURE 3.
To make it easier for the driver to keepin lane, two lines projected parallel on
the road according to the width of thevehicle can be highlighted in front of
the vehicle following the curvature ofthe road. The benefits to the driver will
be greater the more predictive the data
is about the curve ahead of the vehicle.
This can be done via the line detectionof the vehicle camera or via a highly
accurate ADAS map with extensive attributes and use of the Electronic Horizon
system, FIGURE 4.
With the knowledge of the exact­position of the vehicle and the upcoming route, further helpful information supporting the driver can be­displayed. Examples include a warning of a very curvy section of roador the approach to a roundabout,
FIGURE 5 and FIGURE 6.

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FIGURE 2 Turn-by-turn directions from the navigation system can be displayed in good time (© Ford)

FIGURE 3 Never drive too fast again thanks to speed limit display (© Ford)

DISTRACTION BY
THE REPRESENTATION

The fundamental question regarding thepossibilities offered by a pixel headlightis: “What should be displayed?” Signs
and information should be intuitiveand easy to see. Due to the limitationthat the spotlight only emits white light,
there are also limits to what can be displayed. Pictograms are a good choice forquick and easy perception. These meet
all the requirements for the necessaryunambiguous comprehensibility.

With all the assistance provided
to a driver in performing the driving
task, the distraction that such functions
can cause must not be underestimated.
­Activation at the right time is therefore
essential. If activation occurs too early,
the driver expects a situation corresponding to the warning in a timely
manner. If this does not occur, thiscan result in a loss of confidence inthe warning. If the function is activated
too late, it is correspondingly useless.
The intensity of the function or­warning is similar. If the informationwww.springerprofessional.com/automotive

FIGURE 4 The display of lane­markings could make it easierto keep in lane (© Ford)is presented too weakly, it may be perceived poorly or not at all. If the information is presented too intensively andis therefore dominant, it may lose its
supporting effect. It can then become
the primary visual target and thus
reduce the perception of the driving
task again.
The last point to mention is how
the information is activated over time.
The correct activation speed ensures anappearance of the information that isjust the right amount to attract attention, but not yet startling. Basically,
the same applies to the information’s­disappearance: The disappearance of
the information should be as unobtrusive as possible.
With what kind of edge you raise or
lower the brightness plays a subordinaterole. For warnings, it would be advisable

to use a control curve that flashes­something towards the end of its target brightness. For information, on theother hand, a linear display for the eyeis preferable. The correct tuning ofthese parameters is therefore crucial
for meaningful use and thus helpful
for the driver.
GAMIFICATION – DISTRACTION
IN A POSITIVE SENSE

A completely different aspect of a pixel
headlight is the display of moving
images. While driving, this would beaccompanied by a major distraction.
When stationary, however, this can bea distraction, albeit an amusing one,but also a very helpful one.
The subject of the well-being of vehicle occupants is now an integral part ofFIGURE 5 Especially in the dark, the indication of a winding roadmeans additional safety (© Ford)
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02-03|2023   

modern vehicles. Relaxing ambient lighting for the interior, a meditation app, po­­wer nap support or the calming influenceof seat vibrations are just a few of theextras that can be used to make the mostof inactive time, for example during acharging process. So far, this has refer­red
to the interior of the vehicle. But theheadlights could now also contributesomething here with pixel technology.
The idea came about during a test drive
by a development engineer. He got caught
in a traffic jam and came up with theidea that the rear wall of a truck could be
used as a projection surface for the pixel
headlights. The idea of using it for entertainment purposes was born. Because atraffic jam is exhausting and even more
so at night. A simple computer game
could keep the driver active and awake
and thus and thus ensure attention.

FIGURE 6 A roundabout can be announced in good time(© Ford)

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