Patent Publication Number: US-11022519-B2

Title: High-volume, long-range headlamp aiming

Description:
This application is a continuation of U.S. patent application Ser. No. 15/670,754 filed on Aug. 7, 2017 (now U.S. Pat. No. 10,527,519) which in turn is a continuation of U.S. patent application Ser. No. 15/139,622 filed on Apr. 27, 2016, now U.S. Pat. No. 9,863,843, the entirety of the disclosures of each of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates generally to vehicle headlamps. More particularly, the disclosure relates to methods and systems for long-range and high-volume headlamp aiming in a manufacturing/assembly setting. 
     BACKGROUND 
     As is well-known, motor vehicles include front-mounted headlamps to illuminate vehicle-forward and vehicle-lateral portions of a roadway, improving the driver&#39;s ability to see the road and potential hazards or obstacles therein in low-light conditions. A wide variety of headlamp designs are known. At a high level, a vehicle typically includes a pair of front-mounted headlamps disposed substantially at opposed corners of the vehicle front, defining high- and low-beam illumination. This may be done by dedicated high- and low-beam light sources, or by a pair of headlamps each configured to selectively provide a high-beam illumination and a low-beam illumination. 
     It is desirable for a headlamp to illuminate as much of a vehicle-forward portion of a roadway as possible to maximize the ability of the driver to see. Balanced against this design goal is the need to prevent the vehicle headlamps from emitting light in an orientation that will potentially impair the vision of drivers of vehicles traveling in an opposed direction. For that reason, regulations specify that a beam cutoff, which is an upper border between a headlamp illumination falling above and below a particular intensity, must be located at a certain height above the ground at a specified distance in front of the vehicle. 
     To comply with such regulations, headlamps are typically made adjustable to allow the manufacturer and subsequently vehicle users to aim the light emitted from the headlamps as needed to provide a desired beam direction. In particular, vertical headlamp aiming is important since, when improperly aimed, a headlamp aimed too low may reduce low light visibility and object detection, or conversely if aimed too high may create glare, discomfort, and potentially hazard to other drivers. 
     In the manufacturing/assembly context, to analyze/adjust headlamp vertical aim a vehicle under test is placed at a predefined distance from a test surface (colloquially known as a “whiteboard”) and/or measuring device. The headlamps are actuated, and the resulting illumination pattern is analyzed. From the analysis, the headlamps are adjusted to provide the desired illumination direction, beam cutoff, etc. This may occur manually or by use of automated devices, although it is most typical in the manufacturing/assembly context to implement automated/robotic headlamp beam analysis and aiming. Headlamp aiming equipment/systems (“aimers”) are known which use projection analysis or direct measurement of beam cutoff to aim headlamps to nominal position. 
     Various design and manufacturing factors limit the ability to properly aim a headlamp to nominal position. These factors include manufacturing plant photometric aimer capability. Indeed, the general vertical aiming capability of conventional aimers used in the manufacturing/assembly context is limited to ±3 inches at a distance of 25 feet. This is excessive and does not satisfy customer sensitivity to headlamp vertical aim. Another issue is the short fore-aft distance between the headlamp beam pattern, the vehicle, and the camera systems used to analyse beam patterns, which is conventionally 2-5 feet, compared to the much longer distances at which headlamp aim is audited in the production setting (for example 25 feet in the U.S., and 10 meters in Europe). This magnifies the vertical aim error encountered at the conventional audit distance and beyond. 
     Specifically, modern headlamps can have a light beam range in the hundreds of feet. All vertical aim errors introduced during headlamp aiming are angular. Therefore, an error introduced at the 5 foot distance conventionally used for current headlamp analysis equipment is magnified at the normal 25 foot audit distance, and even more so at the headlamps range of hundreds of feet. Because of the 1:5-1:10 ratio between production headlamp aiming (2-5 feet) and conventional production headlamp aim auditing (25 feet), any error in vertical aim is magnified by a factor of 5 or more when the audit is performed, which is significant. 
     Artificial methods have been implemented to compensate for errors introduced by short aiming distances by artificially simulating longer aiming distances, for example Fresnel optical lenses, but are inadequate and indeed may themselves introduce error. A simple solution would be to lengthen the distance between the vehicle and the aiming surface during the production aiming process. However, most production aimers are not and cannot be calibrated for this distance. Moreover, a longer distance between a vehicle and an aiming surface or whiteboard such as 25 feet does not integrate well into current assembly line environment. 
     To solve this and other problems, the present disclosure relates to systems and methods for vehicle headlamp aiming. Advantageously, the described systems and methods allow a significantly longer aiming distance between a vehicle and an aiming surface, but integrate well into current production/assembly lines. By the ability to use longer aiming distances, vertical and other aiming errors are significantly reduced. 
     SUMMARY 
     In accordance with the purposes and benefits described herein, in one aspect a vehicle headlamp aiming system is described, comprising a displaceable aiming surface and an imaging system. The imaging system comprises an indexing aim box including at least one imager oriented to capture images of a headlamp and/or one or more vehicle features adjacent to the headlamp and at least one fixed imager oriented to capture one images of the displaceable aiming surface. The displaceable aiming surface is configured to selectively displace to allow passage of the vehicle. In embodiments, the indexing aim box is configured to translate between the headlamp and another headlamp, for example the right-hand headlamp and the left-hand headlamp of the vehicle, to sequentially block light emitted from the headlamp and the another headlamp. The displaceable aiming surface is positioned a predetermined distance from the vehicle and imaging system during a headlamp aiming procedure. In embodiments, the displaceable aiming surface is positioned at least 25 feet from the imaging system during a headlamp aiming procedure. 
     The system further includes one or more computing devices each comprising at least one processor, at least one memory, and storage, the at least one processor being configured to receive image inputs from the imaging system and to calculate therefrom an aim correction of the headlamp and/or of the another headlamp. An adjuster under the control of the at least one processor may be included to perform the calculated aim correction. 
     In another aspect, methods for aiming a vehicle headlamp using the described system are provided comprising, by at least one indexing aim box imager, capturing at least one headlamp and/or headlamp-adjacent vehicle feature image and determining therefrom a first headlamp optical center. At least one second headlamp low beam light beam cutoff image is captured by at least one fixed imager aimed at a displaceable aiming surface to determine therefrom a second headlamp cutoff height. The vehicle and imagers may be disposed at a predetermined distance from the displaceable aiming surface, which distance may be selected to correspond with an applicable headlamp aim audit distance specified by regulation or otherwise. 
     In a next step, the indexing aim box is translated away from the first headlamp and at least one first headlamp low beam light beam cutoff image is captured by the at least one fixed imager to determine therefrom a first headlamp cutoff height. In embodiments the indexing aim box is positioned to block light emitted from the second headlamp while determining the first headlamp light beam cutoff height, and vice-versa. An aim correction is calculated for the first headlamp and the second headlamp from the determined optical centers of each headlamp and the first headlamp and second headlamp cutoff heights. 
     In embodiments, the aim correction is calculated by providing one or more computing devices each comprising at least one processor, at least one memory, and storage. The at least one processor is configured to receive one or more captured images from the imaging system and to execute computer-readable instructions for determining the first headlamp optical center from the at least one headlamp and/or headlamp-adjacent vehicle feature image, for determining the first headlamp and second headlamp cutoff heights from the at least one first headlamp and second headlamp light beam cutoff image, and for calculating any required aim correction for the first headlamp and the second headlamp. 
     In embodiments, the methods include steps of positioning the vehicle at least 25 feet from the displaceable aiming surface while capturing the at least one headlamp-adjacent vehicle feature image and the at least one first and second headlamp light beam cutoff images. In embodiments, the calculated aim correction may be used to adjust the headlamp aim by an automated adjuster controlled by commands from the processor. On completing the headlamp aim correction, the displaceable aiming surface may be displaced and the vehicle may be translated to a next stop. 
     In the following description, there are shown and described embodiments of the disclosed systems and methods for headlamp aiming. As it should be realized, the systems and methods are capable of other, different embodiments and their several details are capable of modification in various, obvious aspects all without departing from the devices set forth and described in the following claims. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not as restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawing figures incorporated herein and forming a part of the specification, illustrate several aspects of the disclosed systems and methods for vehicle headlamp aiming, and together with the description serve to explain certain principles thereof. In the drawing: 
         FIG. 1A  depicts a vehicle headlamp aiming system according to the present disclosure in side view; 
         FIG. 1B  shows the aiming system of  FIG. 1A  in top view; 
         FIG. 2  shows in flow chart form a process for acquiring headlamp optical center and cutoff height inputs according to the present disclosure; and 
         FIG. 3  shows in flow chart form a process for calculating a headlamp aim correction according to the present disclosure. 
     
    
    
     Reference will now be made in detail to embodiments of the disclosed systems and methods for headlamp aiming, examples of which are illustrated in the accompanying drawing figures. 
     DETAILED DESCRIPTION 
       FIG. 1A  shows a vehicle headlamp aiming system  100  according to the present disclosure. As shown, the system  100  includes a displaceable aiming surface  102  and an imaging system  103  comprising at least a gantry  104  carrying an indexing aim box  106 , and at least one fixed imager  108 . The at least one fixed imager  108  may be supported by the gantry  104 , or may otherwise be substantially fixed in place. In embodiments, the at least one fixed imager  108  may be a high dynamic range camera of known design which takes a series of images at varying exposures, combining images taken at a range of exposures from overexposed, underexposed, and balanced exposure to create a composite image. 
     The indexing aim box  106  includes an imager  110 , which in embodiments is a vision system camera of known design. An adjuster  111  may be provided in association with the indexing aim box  106 , including a suitable mechanism for adjusting a headlamp aim. One such known adjuster  111  comprises an aiming screwdriver operatively connected to a stepper motor, which automatically or under control of a human operator aligns to a headlamp aim adjusting screw to adjust a headlamp aim as needed. 
     In an embodiment (see  FIG. 1B ) the displaceable aiming surface  102  is defined by a pair of parallel pivoting panels  102   a ,  102   b . In alternative embodiments, the displaceable aiming surface  102  may be defined by one or more roller-mounted drop-down panels, a pair of parallel sliding panels, one or more upwardly translatable panels, and others. The caveat is that the displaceable aiming surface  102  is configured to be displaced to allow a vehicle  112  to pass there-through, for reasons which will be explained in detail below. 
     The system  100  is under the control of at least one computing device  113  comprising at least one processor, memory, and storage, configured as will be described below to receive inputs from the imaging system  103  and to calculate any needed aiming corrections for the vehicle  112  headlamps. The computing device  113  may further be configured to control operation of the displaceable aiming surface  102 , the indexing aim box  106 , imagers  108  and  110 , and other elements of the system  100 . 
     In use in an aiming procedure  200  (see  FIG. 2 ), a vehicle  112  is positioned (step  202 ) adjacent to the gantry  104  and the indexing aim box  106  is indexed to a position in front of one of headlamps  114   a ,  114   b . The vehicle  112  may be driven to this position under its own power, or may be translated there by a suitable means, such as a conveyer  116  in a production setting (see arrows A in  FIGS. 1A-1B ). Gantry  104  and indexing aim box  106  are configured whereby the indexing aim box may be translated vertically, cross-vehicle, etc. to position the imager  110  directly in front of a chosen headlamp  114   a ,  114   b . At this point, the displaceable aiming surface  102  is oriented (step  204 ) to provide a suitable aiming surface as shown in  FIG. 1A , whereby beams of light emitted from the headlamps  114   a ,  114   b  will impinge on the aiming surface to provide a portion of the inputs that will be used to determine a needed aiming correction for the headlamps. 
     The vehicle  112  is positioned at a predetermined distance D from the displaceable aiming surface  102 . Using the described system  100 , in an embodiment distance D is selected to comport with regulatory auditing requirements for headlamp aim. For example, in the United States regulatory specifications require a headlamp aim auditing distance of 25 feet, and so the vehicle  112  and imaging system  103  are positioned at least 25 feet from the displaceable aiming surface  102 . Other jurisdictions may require different auditing distances, for example 10 meters in Europe. Alternatively, an increased distance of, for example, 50 feet may provide a more accurate aiming, reduce inline aim error, etc. 
     As will be appreciated, by substantially matching or exceeding a prescribed regulatory aim auditing distance during the actual aiming procedure for headlamps  114   a ,  114   b , audit error is significantly reduced. For example, as summarized above conventional headlamp aiming procedures employed under production conditions dispose a vehicle 2-5 feet from an aiming surface. Under such conditions, assuming a 0.125″ vertical aim error, inline aim error is 0.12 degrees, audit error at 25 feet is 0.63 inches, and the error magnification scale factor is 5. On the other hand, using the presently described headlamp aiming system  100  with a distance D of 25 feet between the displaceable aiming surface  102 /imaging system  103  and assuming the same 0.125″ vertical aim error, inline aim error is 0.012 degrees, audit error at 25 feet is 0.063 inches, and the error magnification scale factor is 0.5. Thus, the geometry of the system  100  reduces vertical aim errors by a factor of 10. Further increasing the distance D between the displaceable aiming surface  102  and imaging system  103  will even further reduce the error magnification scale factor. 
     Next, the indexing aim box  106  is translated (step  208 ) to a position whereby the aim box imager  110  can capture images of first headlamp  114   a  and/or headlamp-adjacent vehicle features (step  210 ) such as the headlamp, an edge of the headlamp, a vehicle grille bar, and others. As is known, such images provide a suitable reference point for determining an optical center of the headlamp  114   a  low beam. In turn, the indexing aim box  106  is dimensioned to substantially prevent light emitted from the first headlamp  114   a  from reaching the displaceable aiming surface  102 . This advantageously reduces stray light interference by light emitted by the first headlamp  114   a  with images of light emitted from the second headlamp  114   b  as will be described. 
     It is contemplated to actuate the headlamps  114   a ,  114   b  low beams (step  206 ) for the step ( 210 ) of determining the headlamp optical center. In such embodiments, the imager  110  may be provided with suitable known filters to allow detection of particular headlamp-adjacent features such as a headlamp edge  116  during the process of aiming an actuated headlamp. It is also contemplated to perform this portion of the described imaging without actuating the headlamps  114   a ,  114   b , i.e. using only ambient light. 
     Prior to, concurrently with, or after the taking of images for determining an optical center of the first headlamp  114   a , the at least one fixed imager  108  obtains one or more images of a light beam emitted by the second vehicle headlamp  114   b  (step  212 ), also on low beam. This occurs by taking images of at least the portion of the displaceable aiming surface  102  contacted by the headlamp light beam. These images are used to determine a cutoff height for the second headlamp  114   b . With reference to the term “cutoff height,” as is known the low beam pattern of a visually-aimable headlamp has a distinct horizontal cutoff below which the light beam is brighter, and above which the light beam is darker. 
     Next (step  214 ), the indexing aim box  106  is translated to a position whereby light emitted by the second headlamp  114   b  is substantially blocked. This concurrently allows light emitted by the first headlamp  114   a  to reach the displaceable aiming surface  102  and reduces stray light interference by light emitted by the second headlamp  114   b  with the images of light emitted from the first headlamp  114   a . The aim box imager  110  captures images of the second headlamp  114   b  and/or headlamp-adjacent vehicle features (step  216 ) such as the headlamp, an edge of the headlamp, a vehicle grille bar, and others. These images are used for determining an optical center of the second headlamp  114   b.    
     Prior to, concurrently with, or after the taking of images for determining an optical center of the second headlamp  114   b , the at least one fixed imager  108  obtains one or more images of a light beam emitted by the first headlamp  114   a  (step  218 ). This again occurs by taking images of at least a portion of the displaceable aiming surface  102 . These images are used to determine a cutoff height for the first headlamp  114   a . Optionally, a cutoff threshold range may be established and headlamp height adjustments may be made to ensure that the first and second headlamp  114   a ,  114   b  cutoff heights are within that threshold. A suitable procedure is set forth in detail in U.S. Pat. No. 8,928,869, the contents of which are incorporated herein by reference in its entirety. 
     With reference to  FIG. 3 , an aim correction calculation process  300  includes steps of providing the above-described images as input to the at least one computing device  113  to calculate any required aim correction for the first and second headlamps  114   a ,  114   b . The computing device processor is configured to include computer-executable instructions for determining a first headlamp optical center and a second headlamp optical center from the above-referenced aim box imager  110  images (step  302 ) Likewise the computing device includes executable instructions for determining first and second headlamp  114   a ,  114   b  cutoff heights (step  304 ) from the above-referenced fixed imager  108  images of light beams striking the displaceable aiming surface  102 . Next (step  306 ), the computing device calculates an aim correction factor for both headlamps  114   a ,  114   b  from the first headlamp  114   a  optical center input, the first headlamp  114   a  cutoff height input, and the second headlamp  114   b  cutoff height input. 
     Finally (step  308 ), the aim correction is input to the adjuster  111 , which performs the required headlamp  114   a ,  114   b  aim corrections. Such adjusters  111  and methods/devices for operating same are well known in the art, and do not require extensive description herein. However, as described above one such known adjuster  111  comprises an aiming screwdriver operatively connected to a stepper motor, which automatically or under control of a human operator aligns to a headlamp aim adjusting screw to adjust a headlamp aim as needed. 
     The process and algorithms for determining headlamp cutoff heights, headlamp optical centers, and aim correction factors from taken images are known in the art. At a high level, the cut-off heights are compared to an ideal headlamp aim height, which is related to a distance between the position of the cut-off (as determined from images taken by the at least one fixed imager  108 ) to a known ground surface supporting the vehicle  112  wheels. Optionally, as described above a threshold range of cutoff heights may be implemented as disclosed in U.S. Pat. No. 8,928,869 
     Optionally, the headlamp  114   a ,  114   b  aim may be verified after the steps of calculating an aim correction and adjusting the headlamp aim, and the above steps may be repeated as needed to ensure proper aiming of the headlamps. In an embodiment, a laser or other focused light projector may be provided which casts a horizontal line image such as a laser line across a width dimension of the displaceable aiming surface  102  at the determined cutoff heights for the first headlamp  114   a  and second headlamp  114   b . This advantageously provides a reference point allowing visual confirmation of correctness of an aim correction procedure performed as described below. That is, by use of the optional focused light projector as described, a user is able to visually confirm that the adjusted cutoff height for the first headlamp  114   a  and second headlamp  114   b  align with the horizontal line projected by the focused light projector. Once the headlamp aiming procedure is completed and any needed aiming corrections applied, the displaceable aiming surface  102  may be displaced (arrows B) as needed to allow passage of the vehicle  112  to a next production line station. 
     The benefits of the presently disclosed systems and methods for headlamp aiming are apparent. The systems and methods are readily adaptable to common production-type settings, for example for incorporating into an assembly line. By keying a calculation of headlamp aim correction to a combination of a headlamp storage compartment aim set point and two determined headlamp cutoff heights, the process of headlamp aiming may be applied to vehicles of a near infinite range of headlamp heights relative to the ground, without requiring aim programs specifically tailored to the vehicle height or a specific headlamp feature. In turn, by using the described indexing aim box to both establish a headlamp optical center and concurrently block light to prevent light spill-over from one headlamp to another headlamp while obtaining a cutoff height for the another headlamp, error is reduced in determining a cutoff height and subsequently aiming the another headlamp. 
     Still more, by the described systems and methods long range headlamp aiming is made feasible in a manner easily integrated into with current production/assembly line settings. This provides a high volume procedure, i.e. a process allowing repeatable, accurate, and efficient aiming of headlamps of many vehicles in an assembly line setting even if the vehicle models are not identical and have differing vehicle (and therefore headlamp) heights relative to the ground. Such long-range headlamp aiming advantageously correlates well with current headlamp aim audit procedures, reducing or eliminating error magnification factors without significantly increasing cost, cycle timing, labor, and other production factors compared to conventional short-range aiming procedures. Indeed, the present systems and methods hold potential for eliminating any need for long-range headlamp aim auditing procedures in the future, further reducing cost, complexity, and plant processes associated with vehicle assembly. 
     Obvious modifications and variations are possible in light of the above teachings. All such modifications and variations are within the scope of the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.