tems with ADB-Functions

Detection Distance and Glare of Headlamp Systems with ADB-Functions
Bastian Zydek, Christoph Schiller, Max Wagner, Dmitrij Polin, Prof. Tran Quoc
Khanh, Laboratory of Lighting Technology, Technische Universität Darmstadt
This research of the University Darmstadt focuses on the quantification of the
abilities of such systems in terms of detection distance and potential glare for
other road users. For this purpose, two vehicles were tested. The first one is a
series vehicle with HID with ADB-functions. The second one is also a series vehicle
with non-adaptive standard halogen headlamps. This approach allows comparing
five headlamp functions:
Table 1: Tested Headlamp Functions
Lamp Type
HID
Halogen
Headlamp Functions
Passing beam
Driving Beam
Glare-Free High Beam
Passing Beam
Driving Beam
Method
As described in Table 1, two vehicles were tested. Both vehicles are series vehicles. One with HID headlamps and activatable Glare-Free High Beam, realized by a
specially shaped drum in the HID projection module. The second vehicle was
equipped with standard halogen reflection headlamps. Both vehicles were aimed
correctly before the execution of the tests.
The tests were conducted on the runway of the August Euler Airport in Griesheim,
Germany under controlled conditions (see figure 1). In total three parameters
were tested for each headlamp function (see Table 1):



Discomfort glare
Disability glare
Detection distance
1
Figure 1: Runway of August Euler Airport
To realize a good comparability, all three parameters were tested at the same
time. Meaning that while a subject was driving a test vehicle to perform a detection test with a certain headlamp function additional subjects were positioned in
oncoming vehicles to give a measure for disability and discomfort glare. This process is hereinafter called “run”. Five vehicles did participate in each run (see figure
2). Four vehicles were positioned as static oncoming vehicles (0 km/h). The fifth
vehicle was one of the two test vehicles, which was driven with one of the five
headlamp functions being activated with a constant speed of 80 km/h. The four
oncoming vehicles were placed with a distance of 180 m to each other. The lane
width was set to 3.5 m. The first oncoming vehicle acted as a calibration vehicle
setting the headlamp system of the test vehicle in a defined status when approaching the other oncoming vehicles.
The tests were performed on four test-days under complete darkness. For each
test-day the participation of seven subjects, one software administrator, one detection object administrator and one examiner was necessary.
2
Figure 2: Test Setup
Discomfort glare
In each run, a total number of four subjects did perform a discomfort glare rating
on the de Boer scale (see figure 3). The subjects were positioned as driver and codriver in the second and third oncoming vehicles (see figure 2). The subjects
were advised to give one rating for one run / passing process. During the runs, the
subjects did not know which vehicle and activated headlamp function would pass
them.
Figure 3: De Boer rating on questionnaire
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The following table shows the involved number of subjects and ratings:
Table 3: Subjects and ratings, detection distance
Lamp Type
HID
Halogen
Headlamp Functions
Passing beam
Driving Beam
Glare-Free High Beam
Passing Beam
Driving Beam
Subjects
16
16
16
10
10
Ratings
102
102
102
77
85
Disability glare
Disability glare quantification was performed in the last oncoming vehicle by two
subjects in driver and co-driver seating position. Both subjects fulfilled a threshold contrast test during each run. Threshold contrast
is the smallest perceptible contrast, meaning that one is just able to differentiate an object with a luminance
from its surrounding luminance
. Threshold contrast increases in
the presence of a glare source making it a measure for disability glare. The increase of threshold contrast can be explained by the fact, that the glare source
generates visible light scattering. This scattering arises in eye media and is described by a so called veiling luminance
. This veiling luminance adds itself to
the object luminance as well as to the surrounding luminance (see figure 4). The
consequence is, that the contrast between object and surrounding decreases
which in return has a threshold contrast increment as a result.
Figure 4: Contrast decrease in presence of glare
What is special is that the threshold test is carried out constantly during each run
meaning that the subjects have to adjust the threshold contrast continuously dur-
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ing each passing process. To fulfill this task two “threshold contrast boxes” were
build (see figure 5).
Figure 5: Threshold contrast boxes
The threshold boxes were positioned in front of the vehicle with a horizontal angle of 2.5° to the detection object. This is equivalent to an object on the right side
of the road at 80 m distance. The object itself is round with a diameter of 0.5°.
The task for the subjects was to adjust the contrast continuously. To realize a variable contrast the threshold contrast boxes contain a dimmable LED. The LED represents the object with
which had to be adjusted in brightness to be just perceptible. To realize a quick reaction of the subjects, the test was designed so that
the brightness increases automatically by 1.5 % every 200 ms. The subjects had
the task to push a button as soon as the object is visible. When pushing the button
the object luminance decreases by 6 %. The distance to the moving test vehicle
was measured by a GPS system. This enabled the authors to match the distance
data to the corresponding threshold contrast. The procedure is visualized in the
following figure:
5
Figure 6: Dynamic threshold contrast
The following table shows the involved number of subjects and ratings:
Table 4: Subjects and ratings, detection distance
Lamp Type
HID
Halogen
Headlamp Functions
Passing beam
Driving Beam
Glare-Free High Beam
Passing Beam
Driving Beam
Subjects
14
14
14
9
9
Ratings
48
48
46
34
38
Detection distance
Detection distance is the distance from the point of the detection of a relevant
object to the object itself. The sooner a driver detects an object the more time
she/he has for a certain reaction. During one run two objects had to be detected
which could appear at three possible positions. All objects were painted to have
the same reflection characteristics, which were also checked by luminance measurement (see figure 7).
6
Figure 7: Detection objects
The task for the subjects was to drive with 80 km/h and to push a button as soon
she/he detects an object. By the use of a GPS system, the distance to the detected
object could be calculated.
The following table shows the involved number of subjects and ratings:
Table 5: Subjects and ratings, detection distance
Lamp Type
HID
Halogen
Headlamp Functions
Passing beam
Driving Beam
Glare-Free High Beam
Passing Beam
Driving Beam
Subjects
8
8
8
5
5
Ratings
42
42
44
32
38
4 Results and Discussion
In this chapter, one can find the results of this investigation. It is important to
remind, that the results for driving beam are only presented for reference. Static
driving beam is generally not activated in an oncoming traffic situation such as it
was tested in this investigation.
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Discomfort glare
The following figure shows the average de Boer rating for each headlamp function
(see table 1). The bars represent the simple standard deviation. The average
values for Halogen passing beam, HID passing beam and HID glare-free high beam
are better than 7.0 (better than satisfactory) on a similar level. This result indicated that the discomfort glare of Halogen lamp and HID lamp headlamps are not
different if the headlamps are correctly adjusted.
Figure 8: Discomfort glare rating
Disability glare
The following figures 9 and 10 show examples of dynamic threshold contrasts
with the corresponding distances. The thick line represents the mean curve. To
compare the different headlamp functions the mean threshold contrast (mean of
thick line) for the distance range of 1000 m to 0 m has been computed. The results
are visualized in the following figure 11. The mean threshold contrast of Halogen
passing beam (5.8), HID passing beam (6.3) and HID glare-free high beam (6.5)
are on the similar level (the difference is statistically not significant).
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Figure 9: Threshold contrast: Halogen, passing beam (driver)
Figure 10: Threshold contrast: Halogen, driving beam (driver)
9
Figure 11: Mean threshold contrast from 1000 m – 0 m (driver & co-driver)
Detection distance
The following figure shows the mean detection distance for each headlamp function. The bars represent the simple standard deviation.
Figure 12: Mean detection distance
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Conclusion
The test described in this paper had the objective to determine the abilities of new
headlamp functions on the basis of glare and detection. This was realized by quantifying detection distance, disability glare and discomfort glare as well as by the
participation of a relative large amount of subjects.
The results of the tests allow drawing three main conclusions:
-
-
-
The presented test concept shows a clear separation of different headlamp functions. Especially the gathering of dynamic threshold contrast
turned out to be a very good method to quantify disability glare in dynamic driving situations.
The passing beam of well-aimed halogen and HID headlamps does almost
not differ in discomfort and disability glare. In contrast to that, HID headlamps realize a substantial increase in detection distance.
In comparison to passing beam, produces a well-designed Glare-free high
beam almost no increase in disability and discomfort glare while realizing
a clear increase in detection distance.
It is important to note, that the presented results are based on two vehicles as well
as on one certain traffic situation. Therefore, further tests shall be done in the next
winter 2014-2015 with more modern car types.
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