Optimization of Automotive Light Distributions for Different Real Life Traffic Situations

The major goal of this thesis is to find a way to optimize current automotive headlamps in order to provide safer nighttime driving. While this has already been done in the past with the works by Damasky and Huhn, the current approach combines methods previously not used in one single study. In the first steps, the influence of different headlamp parameters on viewing distance of the driver is evaluated in field tests. In the second step, the current German traffic space is analysed before in the third step, the gaze behaviour of drivers is recorded and investigated for different situations. The combination of these studies is then used to propose new light distributions. In the first part, field tests are conducted in order to investigate detection distances with different lighting conditions. The gained data is used to provide recommended luminous intensity values for certain detection distances. Furthermore, the data is used to extract luminous intensity recommendations for different angular positions relative to the hot spot. These investigations show, that the current limits set by the ECE for high beam headlamps are sufficient to provide safe detection distances for nearly all situations. However, the data also shows, that low beam should be disregarded for any situation and only be used if high beam cannot be used at all. The traffic space analysis in the second part of this thesis shows, that there are significant differences between different road categories in terms of object location and frequency. For these situations, optimized segment distributions are proposed, leading to significant benefits over the conventional high beam setup. The difference between the proposed segment partitioning and the standard setup is, that the segments are not set equal in size. The segments at the centre of the distribution are set to be smaller in order to better mask out traffic that is further away. Furthermore, it is shown, that the benefit of additional segments is limited at around 280 segments, where a performance identical to a 10000 pixel headlamp is achieved. In the last section, regarding the gaze analysis a large driving test, including 54 test subjects is performed. Here the findings by Diem, Damasky, Brückmann and Weber are confirmed. New approaches regarding the correlation between the driver’s gaze and objects in the traffic space are tested. On a general level, no correlation between the object distribution and the gaze is found. However, a large databank containing object positions as well as driver’s gaze, speed, lighting condition and position in the world is set up for further, more detailed information. The data from all presented studies is then used to propose new, optimized light distributions

Lichttechnische Eignungsprüfung von Retrofit-LEDs als Ersatz für Halogenglühlampen in Kfz-Scheinwerfern

Die Licht-emittierende Diode (LED) gewinnt sowohl in der Haushalts- als auch in der Kfz-Beleuchtung stetig an Bedeutung. Der Umstieg von konventionellen Glühlampen zu LED-Leuchtmitteln erfolgt bereits seit einigen Jahren durch die Verwendung von sogenannten Retrofit-LEDs im Haushalt. Auch in der Kfz-Frontbeleuchtung wäre solch ein Wechsel technisch möglich. In Deutschland und Europa fehlen derzeit jedoch die rechtlichen Rahmenbedingungen für die Zulassung von Retrofit-LEDs. Dabei könnten sich durch die Verwendung von Retrofit-LEDs sowohl Vor- als auch Nachteile bezüglich der Sicherheit im nächtlichen Straßenverkehr ergeben. So könnte der mögliche höhere Lichtstrom und die kältere Lichtfarbe der Retrofit-LEDs zu einer höheren Leuchtweite und somit einer größeren Sichtbarkeitsweite führen. Diese Eigenschaften könnten jedoch ebenfalls für ein erhöhtes Blendpotential sorgen. Mit der durchgeführten Untersuchung wird eine Aussage bezüglich der Sicherheitserhöhung im nächtlichen Straßenverkehr durch die Verwendung von aktuell verfügbaren Retrofit-LEDs getroffen. Hierfür werden sowohl photometrische Messungen im Labor als auch ein Feldtest durchgeführt und ausgewertet

A Novel Way of Optimizing Headlight Distributions Based on Real-Life Traffic and Eye Tracking Data Part 3: Driver Gaze Behaviour on Real Roads and Optimized Light Distribution

In order to find optimized headlight distributions based on real traffic data, a three-step approach has been chosen. The complete investigations are too extensive to fit into a single paper; this paper is the last of a three part series. Over the three papers, a novel way to optimize automotive headlight distributions based on real-life traffic and eye tracking data is presented. Across all three papers, a total of 119 test subjects participated in the studies with over 15,000 km of driving, including recordings of gaze behaviour, light data, detection distances, and other objects in traffic. In this third paper, driver gaze behaviour is recorded while driving a 128 km round course, covering urban roads, country roads, and motorways. This gaze behaviour is then analysed and compared to prior work covering driver gaze behaviour. Comparing the gaze distributions with roadway object distributions from part two of this series, Analysis of Real-World Traffic Data in Germany and combining them with the idealized baseline headlight distribution from part one, different optimized headlight distributions can be generated. These headlight distributions can be optimized for different driving requirements based on the data that is used and weighting the different road types differently. The resulting headlight distribution is then compared to a standard light distribution in terms of the required luminous flux, angular distribution, and overall shape. Nonetheless, it is the overall approach that has been taken that we see as the primary novel outcome of this investigation, even more than the actual distribution resulting from this effort

Optimization of Automotive Light Distributions for Different Real Life Traffic Situations

The major goal of this thesis is to find a way to optimize current automotive headlamps in order to provide safer nighttime driving. While this has already been done in the past with the works by Damasky and Huhn, the current approach combines methods previously not used in one single study. In the first steps, the influence of different headlamp parameters on viewing distance of the driver is evaluated in field tests. In the second step, the current German traffic space is analysed before in the third step, the gaze behaviour of drivers is recorded and investigated for different situations. The combination of these studies is then used to propose new light distributions. In the first part, field tests are conducted in order to investigate detection distances with different lighting conditions. The gained data is used to provide recommended luminous intensity values for certain detection distances. Furthermore, the data is used to extract luminous intensity recommendations for different angular positions relative to the hot spot. These investigations show, that the current limits set by the ECE for high beam headlamps are sufficient to provide safe detection distances for nearly all situations. However, the data also shows, that low beam should be disregarded for any situation and only be used if high beam cannot be used at all. The traffic space analysis in the second part of this thesis shows, that there are significant differences between different road categories in terms of object location and frequency. For these situations, optimized segment distributions are proposed, leading to significant benefits over the conventional high beam setup. The difference between the proposed segment partitioning and the standard setup is, that the segments are not set equal in size. The segments at the centre of the distribution are set to be smaller in order to better mask out traffic that is further away. Furthermore, it is shown, that the benefit of additional segments is limited at around 280 segments, where a performance identical to a 10000 pixel headlamp is achieved. In the last section, regarding the gaze analysis a large driving test, including 54 test subjects is performed. Here the findings by Diem, Damasky, Brückmann and Weber are confirmed. New approaches regarding the correlation between the driver’s gaze and objects in the traffic space are tested. On a general level, no correlation between the object distribution and the gaze is found. However, a large databank containing object positions as well as driver’s gaze, speed, lighting condition and position in the world is set up for further, more detailed information. The data from all presented studies is then used to propose new, optimized light distributions

Anforderungen an die dynamische Leuchtweitenregelung zur Vermeidung der Blendung entgegenkommender Verkehrsteilnehmer

Schon kleine Änderungen in der Fahrzeugneigung können, bedingt z. B. durch Beladung, den Lichtkegel des Scheinwerfers anheben und dadurch Blendung verursachen. Die UN-Regelung Nr. 48 schreibt eine automatische Leuchtweitenregelung (LWR) vor, die den entstandenen Nickwinkel für Scheinwerfer automatisch ausgleicht, falls eine Lichtquelle mit einem Lichtstrom über 2000 lm verwendet wird. Die neueste Entwicklung ist die dynamische LWR, bei der dynamische Neigungsänderungen, z. B. durch Beschleunigungsvorgänge, kompensiert werden. Allerdings gibt es neben dem Lichtstrom-Grenzwert für die automatische LWR keine weiteren Anforderungen an die dynamische LWR. Um Vorschläge für Anforderungen an die dynamische LWR zu erarbeiten, wurden sechs repräsentative Fahrzeuge mit Halogen-, Gasentladungs- und LED-Scheinwerfern untersucht. Diese Fahrzeuge weisen unterschiedliche Federeigenschaften aus und wurden sowohl unbeladen, als auch mit einer Zuladung von 250 kg getestet. Zusätzlich wurde, falls vorhanden, die dynamische LWR deaktiviert und mit aktivierter LWR verglichen. Um die unterschiedlichen Scheinwerfer, Leuchtweitenregelungen und Beladungszustände analysieren und vergleichen zu können, wurden zusätzliche Fahrzeuge verwendet, um Gegenverkehr zu simulieren. Diese Fahrzeuge waren mit einem Photometer ausgestattet und mit Probanden besetzt, deren Aufgabe darin bestand, die psychologische und physiologische Blendung zu bewerten. Die Ergebnisse zeigen, dass die Fahrzeugneigung durch eine Vielzahl von Parametern beeinflusst wird und Blendung nur durch eine verpflichtende Anwendung der dynamischen LWR reduziert werden kann. Im zweiten Teil dieser Untersuchung wurden Kfz-Werkstätten daraufhin überprüft, inwieweit diese die Scheinwerfer in Bezug auf die Anforderungen der UN-Regelung korrekt einstellen. Aus diesem Grund wurden Halogen- und Gasentladungs-Scheinwerfer von zwei Fahrzeugen definiert verstellt, um sie anschließend von Werkstätten justieren zu lassen. Die Analyse der Daten zeigen, dass die Scheinwerfer im Mittel um -1,25 % zu tief ausgerichtet werden.Even small changes in the vehicle inclination, for example due to added load, can lead to changes in the light beam and result in higher glare. The UN-Regulation No. 48 requires a levelling system that has to work automatically for headlamps with a light source emitting a luminous flux over 2000 lm. The latest development in levelling is dynamic levelling, which is able to compensate dynamic vehicle inclination, for example during acceleration. Besides the 2000 lm requirement for automatic levelling, there is no further requirement for the dynamic levelling. To propose requirements for dynamic headlamp levelling devices, six representative vehicles with tungsten halogen, high intensity discharge (HID) and light emitting diode (LED) headlamps were examined. These vehicles had different suspension stiffness and were tested empty and with an added load of 250 kg. Furthermore, dynamic levelling was deactivated where available, and compared to the activated system. To assess and compare the different headlamps, headlamp levelling devices and load conditions, additional vehicles were placed on the track to simulate oncoming traffic. These vehicles were equipped with photometers and subjects to rate discomfort and disability glare. The results show that vehicle inclination is being influenced by numerous of parameters and only the mandatory use of a dynamic headlamp levelling device can potentially prevent glare. In the second part of the study, the ability of repair shops in aiming headlamps regarding the UN-Regulation requirements was examined. For this reason, the headlamps of two vehicles with tungsten halogen and HID headlamps were misaligned and brought to selected repair shops in order to realign them correctly. After analyzing the data, it was found that headlamps were aimed too low with a mean vertical value of -1.25 %

Contrast determination based on object detection distances under peripheral vision conditions and conclusions for future lighting distribution concepts

The visual tasks consist in perception of presence (detection) of objects. If the luminance of the object to be detected is high enough (related to its environment) to achieve 99% detection probability at a distance that is longer than the stopping distance of the vehicle accidents can be avoided. The state of the art in front lighting systems are adaptive driving beam) modules using LED pixels. Developing efficient glare free high beam systems is on the one hand to eliminate glare by dimming luminous intensity, on the other hand to increase the luminous intensity and thereby the visibility of the visual field of the driver. Hence, the question to be asked is, how the light intensity for every angle segment (pixel) should be defined in order to prevent glare, and more importantly, to detect the objects for relevant eccentricities with a high probability