Browse Topic: Headlamps
Welcome, once again, to our annual digital-only issue. We remain committed, of course, to our eight print issues each year, but letting the benefits of digital media come to the fore is always its own fun challenge. No matter what your role is, you should find something engaging and educational among these virtual pages. We've got videos, animations and other multimedia components for you to click on and learn from in this issue. My personal favorite example in here of a video replacing a thousand words can be found in our cover story. It's not like the text is indecipherable, but simply seeing how adaptive headlight beams adjust where they throw their high beams so as to not blind other drivers in almost all situations is just cool. Headlight technology has come a long, long way in the last decade, from the low lights of old helping clear a path home to today's often-annoying high beams that may provide extra safety to the driver, but make the blood of oncoming drivers run dry.
A demonstration ride shows the glare-free, game-changing power of adaptive driving beams, already available in Europe. An approval test from NHTSA is proving difficult for OEMs to pass. I'm riding in the second row of a Lincoln Navigator fitted with Forvia Hella's adaptive driving beam (ADB) headlight system. The low- and high-beams are on, blasting everything in front of us for between 350 and 500 feet (122 and 152 m) with a bright, daylight-temperature LED light. Even traffic and street signs at the edges of the road, which normally aren't as well illuminated, are bathed in brightness. A car pulls out in front of us, and the system instantly adjusts, creating a tunnel of unlit space on and just next to the vehicle ahead. So even though we still have high beams on the rest of the road, that driver isn't facing the harsh glare that is the No. 1 complaint about today's high-intensity headlight systems.
The objective of this study was to examine the effect of Correlated Colour Temperature (CCT) of automotive LED headlamps on driver’s visibility and comfort during night driving. The experiment was conducted on different headlamps having different correlated colour temperatures ranging from 5000K to 6500K in laboratory. Further study was conducted involving participants of different age group and genders for understanding their perception to identify objects when observed in light of different LED headlamps with different CCTs. Studies have shown that both Correlated Colour Temperature and illumination level affect driver’s alertness and performance. Further study required on headlamps with automatically varying CCT to get better solution on driver’s visibility and safety.
Headlight glare remains a persistent problem to the U.S. driving public. Over the past 30 years, vehicle forward lighting and signaling systems have evolved dramatically in terms of styling and lighting technologies used. Importantly, vehicles driven in the U.S. have increased in size during this time as the proportion of pickup trucks and sport-utility vehicles (SUVs) has increased relative to passenger sedans and other lower-height vehicles. Accordingly, estimates of typical driver eye height and the height of lighting and signaling equipment on vehicles from one or two decades ago are unlikely to represent the characteristics of current vehicles in the U.S. automotive market. In the present study we surveyed the most popular vehicles sold in the U.S. and carried out evaluations of the heights of lighting and signaling systems, as well as typical driver eye heights based on male and female drivers. These data may be of use to those interested in understanding how exposure to vehicle headlighting and other factors have changed in the recent past.
To ensure adequate visibility without excessive glare, vehicle headlights are designed to use a specific source of illumination. The optical designs of headlights gather the luminous flux produced by the light source to produce a useful beam pattern that meets the relevant requirements and standards for vehicle forward lighting. With the advent of solid state, light emitting diode sources for general illumination, an increasing number of LED replacement headlight bulb products has emerged over the past decade. In most cases, these LED replacement bulbs are not permitted for legal use on public roadways, but some countries have begun to permit specific LED replacement bulbs to be used legally on the road for specific makes, models and production years of certain vehicles. If they can be demonstrated to produce a beam pattern that meets the photometric requirements for a legal headlight, they are permitted to be used legally for on-road use. In the present paper we present photometric measurement data for two North American headlight systems originally designed for halogen bulbs. Each was fitted with a halogen bulb and with two different LED replacement bulbs and measured at specific angles to check photometric compliance with the minimum and/or maximum luminous intensity at those angles. We also present data on the illuminances produced at several locations along a hypothetical roadway to compare performance between the headlights with halogen bulbs and with each LED bulb.
Headlamps should illuminate the traffic scene ahead of the vehicle in such a way that the driver can operate the vehicle safely and in a relaxed manner. At the same time, negative effects on drivers of other vehicles, pedestrians and other people should be minimized. Various technical parameters such as beam pattern, mounting height, headlamp aiming, and source spectrum can be tuned to find the necessary compromise. The physiology of the vision system under specific nighttime conditions strongly influences these factors and how headlamps can be best optimized for visibility and comfort. The SAE Improved Roadway Illumination task force collected and reviewed relevant research on these topics. This document is a comprehensive summary of this information. The goal is to enable lighting experts, advocacy groups, and non-experts (journalists, consumer organizations, car drivers) to better understand the benefits and tradeoffs of improved roadway lighting with modern headlamp technology. It should be noted that all studies cannot be included in this report, but the intent of this document is to provide the reader with a representative sample of the existing research as a starting point. Further, this document can be updated in the future to reflect new research findings.
As new headlight technologies begin to take hold in vehicular forward lighting systems and they become more commonplace on vehicles, new frameworks for evaluating the performance of these systems are being developed and promulgated. The objective of each of these systems is the same, namely, improving safety by ensuring that vehicle lighting provides sufficient visibility for drivers without negative impacts such as glare. Recent research has shown the direct link between improved driver visibility and reduced nighttime crashes. To the extent that headlight evaluation systems can be compared using visual performance modeling approaches, it should be possible to relate improved visibility from high-performing headlight systems to the potential for reduced nighttime crashes. In the present paper we demonstrate how visual performance modeling in conjunction with vehicle headlight evaluations can lead to predictions of improved safety and ultimately, beneficial economic impacts to society.
When designing new vehicles, the legal requirements of the countries in which the vehicles are homologated must be observed and implemented. The manufacturers try to consider the legal framework of the UN-ECE (United Nations Economic Commission for Europe), CCC (China Compulsory Certification) and FMVSS (Federal Motor Vehicle Safety Standard) 108 in the same vehicle to keep the variance low. For the appearance of the vehicle, the position of the light modules in the front of the vehicle is important. In addition to the surface requirements of lighting functions, the positions of the low beam (LB), high beam (HB) and the position of daytime running lights (DRL) are also regulated. When it comes to these mounting positions, the legislation between the US and the EU differs quite significantly. The UN-ECE legal framework does not describe the distance between the left and right Adaptive Front Lighting System with a certain value, but only requires the distance to the outer edge of the vehicle to be less than 400 mm. The FMVSS 108 on the other hand stipulates, that the distance should be "as far apart as practicable". The underlying reason for that is, that the distance and width from oncoming traffic could be misjudged if the low beam is placed too far inboard of the vehicle instead of to the outer edges. For this reason, with the support of a test person study, this paper examines different horizontal mounting positions of low beam in combination with several light setup positions, to investigate the impact of the headlight position on the distance assessment. The results can be used to design future cars in such a way that innovative design can be implemented while ensuring road safety.
Visual sensors are widely used in autonomous vehicles (AVs) for object detection due to the advantages of abundant information and low-cost. But the performance of visual sensors is highly affected by low light conditions when AVs driving at nighttime and in the tunnel. The low light conditions decrease the image quality and the performance of object detection, and may cause safety of the intended functionality (SOTIF) problems. Therefore, to analyze the performance limitations of visual sensors in low light conditions, a controlled light experiment on a proving ground is designed. The influences of low light conditions on the two-stage algorithm and the single-stage algorithm are compared and analyzed quantificationally by constructing an evaluation index set from three aspects of missing detection, classification, and positioning accuracy. Five main environmental influencing factors are tested and analyzed in typical nighttime urban driving scenarios: illuminance, the lateral movement of the object, the longitudinal distance of the object, the high beams of the oncoming vehicle, and the low beams of the ego vehicle. The test results show that the performance limitations of recognition algorithms can be triggered by the low illuminance, the lateral movement of the object, the long longitudinal distance of the object, and the high beams of the oncoming vehicle. For different types of recognition algorithms, the performance of Faster R-CNN is better than that of YOLOv5 in most scenarios. As for the environmental factor, the low beams of the ego vehicle, it can improve the performance of recognition algorithms in low light conditions when the longitudinal distance of the object is less than 87.5m. This paper provides a reference for the design and performance evaluation of visual sensors for AVs, as well as improving SOTIF performance.
This SAE Information Report will explain the differences between Class A, B, and C networks and clarify through examples, the differences in applications. Special attention will be given to a listing of functions that could be attached to a Class A communications network.
Automotive headlamp designs have evolved considerably over the years, shifting from a utilitarian component of a vehicle to being a major part of its overall styling, particularly for the Front of the vehicle. In addition to this, Headlamps are a ‘mission-critical’ safety feature, especially for driving at night or in poor weather conditions. For this reason, they are subject to high performance requirements and must meet stringent automotive and highway safety standards. Modern headlamps are becoming bigger and heavier to accommodate attractive features like DRL lamps, Projector lamps and Adaptive lamps. The increased weight of the headlamp poses additional challenges with respect to the durability and loss of bolt preload during high road load events.
The main task of the automotive headlights on cars is to illuminate the roadway and facilitate the driver fatigue-free and safe driving. An automotive headlamp is exposed to thermal variations during its operations and also exposed to the different environmental conditions. Automotive headlamp compartment is not completely sealed and vents are provided to exchange the air between environment and headlamp compartment for thermal cooling of the internal components. An automotive headlamp compartment is an environment with high thermal and low air flow exchanges with the ambient as results humidity can accumulated inside the headlamp compartment and there is a possibility of thin mist layer formation on the lens inner surface [1]. The combined use of numerical simulation and experimental studies is an important approach for headlamp design. This paper summarizes CFD simulation results for automotive headlamp condensation and de-condensation using ANSYS FLUENT. In this study, transient multiphase fluid flow with natural convection, conduction and radiation heat transfer were performed along with species transport. Radiation heat transfer is modelled using “Discrete Ordinate” (DO) model [2] which takes into account of heat transfer through semi-transparent media. Multiphase flow is modelled using Eulerian wall film approach which models condensation and de-condensation of water vapor. The variable diffusivity of the water vapor inside the headlamp compartment is defined using user defined function in ANSYS FLUENT. Both CFD and experimental results are presented in this paper, which shows good agreement, demonstrating enormous potential of proposed CFD based approach for reduced product development and cost.
Automotive exterior lighting systems has to meet several regulatory requirements & manufacture specific internal standards to achieve desired performance. These test specifications are usually generic in nature and formulated mainly to validate the standalone product under standard laboratory conditions. Most of the time these specifications are common for entire vehicle portfolio. The rationale of these standards is to define the basic illuminance in the safe braking distance. Thus, however, using the requirements in these standards to evaluate the performance of front lighting systems is only qualitative. Research on working out method for quantitative evaluation of front lighting system is necessary [1] In practice, however, the luminance levels at road surfaces are usually very dynamic; depend largely on the variations in vehicle parameters, ambient weather conditions, road surface uniformities and effects of light intensity & color contrasts on target visibility. Unavailability of such assessment mechanism has motivated the authors to generate test specifications & measurement methodology. One objective of this work is to bring actual road scenario into laboratory environment to identify and introduce an advanced evaluation approach for photometric performance assessment of lighting system in terms of its intensity, range and reduction in glare under various weather conditions, vehicle design parameters and road conditions. This subjective evaluation is the judgmental methodology to identify the effect of these variables. Test results were analyzed to understand the acceptable limits of light intensity & color combination to achieve desired performance. The results gives border view to take judgmental decision for optimized performance when the product is in design stage itself, making evaluation process more robust and avoids performance evaluation on physical proto type, which usually requires many iterations, time-consuming and adversely affects project timeline.
Transportation safety agencies are working to consider how to best incorporate the potential safety benefits of intelligent vehicle lighting systems such as adaptive driving beam headlights and other systems on vehicles used by the general public. As these deliberations continue, additional data on the impacts of lighting technological developments are important to generate and share. An analytical study was performed to assess how different vehicle lighting configurations including ADB and other technologies can assist drivers in achieving visual acquisition of potential hazards along the road. The investigation also compared drivers varying in age and whose visual performance differs because of optical changes in the visual system. The importance of considering visibility for older drivers is critical because this group is an increasingly large proportion of the overall driving population. Analyses use the relative visual performance (RVP) model, a predictive system for ascertaining the speed and accuracy of visual processing, which has been validated in a number of field studies of driving and visual response. The results can be used to identify some of the potential benefits of intelligent vehicle lighting on visual perception.
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