Method and device for recognizing an illuminated roadway ahead of a vehicle

Abstract

A method for recognizing an illuminated roadway ahead of a vehicle, having a step of recognizing a first light object as a first roadway illumination unit. The method also includes a step of ascertaining a distance covered by the vehicle. The method also includes a step of recognizing a second light object as a second roadway illumination unit. The method also includes a step of providing a signal when the first roadway illumination unit and the second illumination unit have been recognized. The signal is provided using the distance covered, the signal representing a recognition of an illuminated roadway ahead of a vehicle.

Claims

1. A method for controlling a light emission by headlights of a vehicle, the method comprising: detecting, by a control unit processing at least one sensor signal, a first light object as a first roadway illumination unit at a first point; detecting, by the control unit processing at least one sensor signal, a second light object as a second roadway illumination unit at a second point; ascertaining, by the control unit, a distance covered by the vehicle between the first and second points; detecting, by the control unit and based on the ascertained distance covered, a characteristic of an illuminated roadway ahead of the vehicle; and responsive to the detection of the illuminated roadway, controlling, by the control unit, the headlights of the vehicle to change the light emission of the headlights.

2. The method as recited in claim 1, wherein the controlling includes outputting a signal responsive to at least one of: i) the first roadway illumination unit being detected over the distance which is greater than a first predetermined reference distance, and ii) upon detection of the second roadway illumination unit, the distance covered being less than a second predetermined reference distance.

3. The method as recited in claim 1, wherein the controlling includes outputting a signal responsive to, upon detection of the second roadway illumination unit, an angle between a vehicle longitudinal axis and a direction from the first or the second roadway illumination unit being less than a predetermined angle threshold value, and the distance covered after detecting the second roadway illumination unit being greater than a first predetermined reference distance.

4. The method as recited in claim 3, wherein the controlling includes outputting a signal responsive to, upon detection of the second roadway illumination unit, the angle between a vehicle longitudinal axis and a direction from the first or the second roadway illumination unit being greater than the predetermined angle threshold value, and the distance covered after detecting the second roadway illumination unit being greater than a second predetermined reference distance.

5. The method as recited in claim 1, wherein the controlling includes outputting a signal responsive to at least one further roadway illumination unit being detected.

6. The method as recited in claim 1, wherein the controlling includes outputting a signal responsive to, subsequent to a non-detection of roadway illumination units, a further roadway illumination unit being detected when the distance covered after the non-detection is less than a predetermined reference distance.

7. The method as recited in claim 6, wherein the controlling includes outputting a signal responsive to another roadway illumination unit being detected, and the distance covered after the non-detection being less than another predetermined reference distance, the signal representing the detection of the illuminated roadway ahead of a vehicle.

8. The method as recited in claim 6, wherein the controlling includes an adaptation of at least one parameter that represents the predetermined reference distance, the predetermined reference distance being increased responsive to the non-detection.

9. The method as recited in claim 1, wherein the controlling to change the light emission is not performed when a brightness of the surroundings is less than a predetermined threshold value.

10. The method as recited in claim 1, wherein the ascertaining step is discontinued when a yaw rate of the vehicle is greater than a predetermined yaw rate threshold value.

11. A device for controlling a light emission by headlights of a vehicle, the device comprising: at least one sensor; processing circuitry; an input; and an output; wherein the processing circuitry is programmed, by a hardwired configuration or by software, with a program that is executable by the processing circuitry and that, when executed by the processing circuitry, causes the processing circuitry to: detect, by processing at least one sensor signal obtained from the at least one sensor via the input, a first light object as a first roadway illumination unit at a first point and a second light object as a second roadway illumination unit at a second point; ascertain a distance covered by the vehicle between the first and second points; determine, based on the ascertained distance covered, a characteristic of an illuminated roadway ahead of the vehicle; and responsive to the detection of the illuminated roadway, control, via the output, the headlights of the vehicle to change the light emission of the headlights.

12. A non-transitory computer-readable storage medium storing program code that is executable by a processor and that, when executed by the processor, causes the processor to perform a method to control a light emission by headlights of a vehicle, the method comprising the steps of: detecting, by processing at least one sensor signal, a first light object as a first roadway illumination unit at a first point; detecting, by processing at least one sensor signal, a second light object as a second roadway illumination unit at a second point; ascertaining a distance covered by the vehicle between the first and second points; determining, based on the ascertained distance covered, a characteristic of an illuminated roadway ahead of the vehicle; and responsive to the determination of the illuminated roadway, controlling the headlights of the vehicle to change the light emission of the headlights.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is explained in greater detail below as an example, with reference to the figures.

(2) FIG. 1 shows an illustration of a vehicle having a device for recognizing an illuminated roadway according to one exemplary embodiment of the present invention.

(3) FIG. 2 shows a flow chart of a method for recognizing an illuminated roadway according to one exemplary embodiment of the present invention.

(4) FIG. 3 shows a flow chart of a method for recognizing an illuminated roadway according to one exemplary embodiment of the present invention.

(5) FIGS. 4a through 4c show Petri nets for method subsequences of a method for recognizing an illuminated roadway according to one exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(6) In the following description of preferred exemplary embodiments of the present invention, identical or similar reference numerals are used for the elements having a similar action which are illustrated in the various figures, and a repeated description of these elements is dispensed with.

(7) A recognition of continuous roadway illumination is also important when other high-beam assistant systems such as adaptive high-beam control (AHBC), which is related to the sliding headlight range control, or a glare-free high beam are to be used, since these systems may also be regarded as high-beam light distribution. The vehicle detection in darkness (VDD) algorithm recognizes streetlamps in the image, which may be utilized to recognize continuous roadway illumination.

(8) A simple assumption that a continuous roadway illumination signal (with appropriate switchover to low beam or a special light distribution for city light) is generated as soon as roadway illumination has been recognized is not meaningful. Intersections/traffic circles exist which are equipped with streetlamps. These should not be recognized as continuous roadway illumination, since otherwise the low beam would have to be activated too frequently. Thus, roadway illumination is not always continuous.

(9) The expanded assumption that a specific location is in a continuously illuminated area when more than one streetlamp is visible at the same time is likewise prone to major error. Multiple streetlamps are not necessarily in the visible range in a continuously illuminated area, since it is possible that a maximum of one streetlamp is visible due to obscurations in curves, etc. It is possible that sometimes there may be no streetlamp in the visual field within a continuously illuminated area (for example, at intersections, sharp curves, etc.).

(10) Since streetlamps are self-illuminating light sources, they may be seen from a great distance. A premature recognition of the continuous roadway illumination results in (excessively) early switchover to low beam. The driver thus unnecessarily loses a valuable range of visibility.

(11) FIG. 1 shows an illustration of a vehicle 100 having a device 102 for recognizing an illuminated roadway ahead of vehicle 100 according to one exemplary embodiment of the present invention. Vehicle 100 has headlights 104 and a camera 106. Device 102 has a unit for recognizing 108, a unit for ascertaining 110, and a unit for providing 112. Unit for recognizing 108 is designed to read in image data from camera 106 which represent an image of camera 106. When the image data depict at least one roadway illumination unit as a light object, the unit for recognizing 108 is designed to recognize the light object as a roadway illumination unit. Unit for ascertaining 110 is designed to ascertain a distance covered by vehicle 100. When unit for recognizing 108 has recognized a first roadway illumination unit, unit for ascertaining 110 thus begins to ascertain a distance covered by vehicle 100 while the first roadway illumination unit is recognizable in the image data. When unit for recognizing 108 recognizes a further roadway illumination unit, unit for ascertaining 110 provides the distance covered by vehicle 100 between the points of ascertaining, and also ascertains the instantaneous distance covered. Unit for providing 112 is designed to provide a signal when the first roadway illumination unit and the second roadway illumination unit have been recognized. A point in time of the provision is determined by using the distance covered. For example, the signal may be provided when the second roadway illumination unit is recognized after the first roadway illumination unit has been recognized at least for a length of a first reference distance, and the distance covered until recognizing the second roadway illumination unit is less than a second reference distance. Likewise, the signal may be provided when the second roadway illumination unit has been recognized, while the distance covered since recognizing the first roadway illumination unit is less than the first reference distance, and, subsequent to recognizing the second roadway illumination unit, vehicle 100 has covered a third reference distance. The signal is provided for a light control unit 114 which controls headlights 104. Light control unit 114 receives further information from other sources, in the present exemplary embodiment from camera 106, in order to control the light from headlights 104. The signal of control unit 102 is designed to influence light control unit 114 when vehicle 100 travels into and/or on a roadway segment having continuous roadway illumination, and/or leaves the roadway segment. Light control unit 114 then specifies an illumination scenario for headlights 104 which complies with legal requirements.

(12) FIG. 2 shows a flow chart of a method 200 for recognizing an illuminated roadway ahead of a vehicle according to one exemplary embodiment of the present invention. Method 200 may be carried out in a device as illustrated in FIG. 1. Method 200 has a step of recognizing 202, a step of ascertaining 204, a further step of ascertaining 206, and a step of providing 208. A first light object is recognized as a first roadway illumination unit in step 202. When the first roadway illumination unit is recognized, an ascertainment of a distance d covered by the vehicle is started in step 204a. A second light object is recognized as a second roadway illumination unit in step 206. When the second roadway illumination unit is recognized, distance d covered is ascertained in step 204b. A signal is provided, using distance d covered, in step 208 when the first roadway illumination unit and the second roadway illumination unit have been recognized.

(13) FIG. 3 shows a flow chart of a method for recognizing a continuously illuminated roadway with the aid of camera images of a camera of a vehicle according to one exemplary embodiment of the present invention.

(14) When a first light object is recognized in camera images as a first roadway illumination unit, a counter n is set from zero to one. A distance meter for a distance d covered by the vehicle is set to a predefined value, in the present case zero, when the first roadway illumination unit is recognized. A counter reading of the distance meter increases until the first roadway illumination unit is recognized. The counter reading increases in proportion to distance d covered while the vehicle covers the distance.

(15) When the first roadway illumination unit is no longer recognized, while distance d covered is less than a first reference distance D1, counter n is reset to zero.

(16) When a second light object is recognized as a second roadway illumination unit, while distance d covered is less than first reference distance D1, counter n is set to two.

(17) When a second light object is recognized as a second roadway illumination unit, and the first roadway illumination unit has been continuously recognized over a distance that is greater than first reference distance D1, and distance d covered is less than a second reference distance D2, a roadway illumination signal S is provided. Street illumination signal S is provided at least until at least one roadway illumination unit is recognized.

(18) If no further roadway illumination unit is recognized, while distance d covered is less than second reference distance D2, counter n is reset to zero.

(19) If the second roadway illumination unit is recognized, while distance d covered is less than first reference distance D1, the distance meter may be reset to the predefined value, in the present case zero.

(20) If the roadway illumination unit has a smaller vertical angle with respect to the vehicle than a reference angle REF, roadway illumination signal S may be provided when distance d covered is greater than a third reference distance D3.

(21) If the first roadway illumination unit has a larger vertical angle with respect to the vehicle than reference angle REF, roadway illumination signal S may be provided when distance d covered is greater than a fourth reference distance D4.

(22) If a roadway illumination unit is no longer recognized, the distance meter is set to the predefined value, in the present case zero. The counter reading of the distance meter increases as long as the vehicle is moving.

(23) Street illumination signal S may also be provided when distance d covered since the setting of the distance meter is less than a fifth reference distance D5, and a further light object is once again recognized as a roadway illumination unit.

(24) Street illumination signal S may be discontinued when distance d covered is greater than fifth reference distance D5 and no further light object is recognized as a roadway illumination unit.

(25) Street illumination signal S may be provided once again without delay when a further light object is recognized as a further roadway illumination unit, and distance d covered is less than a sixth reference distance D6.

(26) Subsequently adapting parameters, in particular increasing fifth reference distance D5, has proven to be particularly advantageous, and may be carried out for a subsequent step of providing an adaptation to uncommon roadway and roadway illumination conditions.

(27) If distance d covered since the setting of the distance meter is greater than sixth reference distance D6 and no further light object is recognized as a roadway illumination unit, counter n is reset to zero.

(28) FIGS. 4a, 4b, and 4c show illustrations of Petri nets of multiple method components according to one exemplary embodiment of the present invention. A Petri net represents relationships among various states and conditions.

(29) FIG. 4a shows a Petri net for the case that at least two roadway illumination units are recognized in rapid succession. The recognition of continuous roadway illumination is carried out (in a state-based manner) based on the number and position of the streetlamps in the image and their duration of visibility. Streetlamps are spaced apart at a fixed (but not defined) distance, since they are stationary objects. It is therefore advantageous to carry out the ascertainment of the duration of visibility based on the distance (distance measurement). The duration of visibility is thus independent of the vehicle speed (in contrast to time-based assessment of the duration of visibility). To recognize continuous roadway illumination, it is necessary to detect a minimum number of streetlamps within a certain distance. The distance varies depending on the configuration of the streetlamps.

(30) FIG. 4a shows the case that multiple streetlamps minimum number) are recognizable in the image. If the position of the streetlamps in the image is far to the top and/or the estimated distance is close, distance d necessary to generate a continuous streetlamp signal is reduced: it is likely that the vehicle is already situated directly prior to/in the continuously illuminated area in which use of the high beam is prohibited. The distance covered is measured independently of the position of the streetlamps. The continuous roadway illumination signal may thus be generated more quickly upon approaching a continuously illuminated area when the streetlamp increasingly shifts to a closer/higher position.

(31) For example, two streetlamps (minimum number) are visible in the image. The roadway illumination signal is generated when these two streetlamps (or any other arbitrary number in the image) are continuously visible for 50 m (=d1). However, if at least one of the streetlamps is close enough to the vehicle (i.e., high enough in the image), the roadway illumination signal is generated after just 30 m (d2). If the streetlamps are present there after 49 m (d<d1, d>d2), the continuous illumination signal is immediately generated, since distance d traveled is not reset. The same applies for 31 m (<d1, >d2). If the streetlamps are close (pass-by signal) after 20 m, for example (<d2), the continuous illumination signal is not generated until after d2 lapses, i.e., after a further 10 m.

(32) The starting point is a state 400 (no illumination) in which no streetlamps are recognized. When a condition 400a (sufficient streetlamps, start distance measurement d) is met, the method switches into a state 402 (streetlamp distant) in which the streetlamps are recognized as distant. If a condition 400b (too few streetlamps (<minimum number) appear) is met, the method switches into a state 404 (few streetlamps) in which few streetlamps are recognized. In state 402 the method switches into a state 406 (illumination) in which continuous roadway illumination is recognized when condition 402a (d>d1) is met that a distance traveled is greater than a first reference distance. When a condition 402b (pass-by signal (streetlamp is close/high)) is met that the streetlamps are recognized at a vertical angle that is greater than a threshold angle, the method switches into a state 408 (streetlamps close) in which the streetlamps are recognized as close. Starting from state 408, the method switches into state 406 when condition 408a (d>d2), where d2<d1, is met that the distance traveled is greater than a second reference distance, the first reference distance being greater than the second reference distance. When the method has reached state 406, continuous illumination signal 410 is generated.

(33) FIG. 4b shows a further Petri net for the case that at least two roadway illumination units are recognized, the second roadway illumination unit being recognized only after the vehicle has covered a greater distance.

(34) After the distance measurement has been started, in state 404 (streetlamp(s) in image) a switch is made into a state 412 (wait for disappearance) when a condition 404a (d<d3) is met that distance d covered is greater than a third reference distance. In state 412, a switch is made into a state 414 (wait for further streetlamp) when a condition 412a (streetlamp has disappeared; restart distance measurement) has been met. In state 414 a switch is made into state 406 (illumination) when a condition (d<d4 and streetlamp has appeared) is met that distance d covered is greater than a fourth reference distance, and a roadway illumination unit has been recognized. When the method has reached state 406, continuous illumination signal 410 is generated.

(35) If the streetlamp(s) disappear/disappears from the visible range in state 404 (streetlamp(s) in image) before the measured distance is great enough for the switch into state 412 (wait for disappearance), a switch is made into state 400 (no illumination). The same applies if no streetlamp appears within distance d4 in state 414 (wait for further streetlamps). If the minimum number is greater than two, the number of streetlamps which have appeared and are continuously visible may be summed. If a new streetlamp does not appear within distance d4, a switch is made back to state 400 (no illumination) or to an intermediate state if the individual distances of the streetlamps are separately tracked (each streetlamp has its own measured visibility distance). The allowable distance between the appearance of new streetlamps must not exceed distance d4.

(36) FIG. 4c shows a further Petri net for the case that no further roadway illumination unit is recognized, and subsequently after a distance covered a further roadway illumination unit is recognized once again, for example when driving through an area having continuous roadway illumination in which at least one streetlamp is obscured.

(37) Starting from state 406 (illumination), a switch is made into state 414 (wait for streetlamp) when condition 406a (no more streetlamps visible; start distance measurement) is met. Continuous illumination signal 410 continues to be generated in state 414. If condition 414b (streetlamp) is met in state 414 that a roadway illumination unit is once again recognized, the method switches again into state 406. If condition 414c (d>d6; restart distance measurement) is met in state 414 that the distance covered is greater than a sixth reference distance, the method switches into an indeterminate state 416 (uncertain state) in which the continuous illumination signal 410a is not generated. This uncertain state is a state in which the system is not certain whether the vehicle has actually traveled out of an illuminated roadway area, or just that no roadway illumination unit has been recognized, for example because the next streetlamp is obscured by trees or is situated behind a curve or a crest in the roadway. If condition 416a (streetlamp) in this state 416 is met that a roadway illumination unit is once again recognized, the method switches once again into state 406. If condition 416b (d>d7 (where d7<d1)) in state 416 is met that the distance covered is greater than a seventh reference distance, the seventh reference distance being greater than the first reference distance, the method switches into state 400 (no illumination).

(38) If the vehicle has traveled out of an area having continuous roadway illumination, a continuous roadway illumination signal should no longer be generated. As soon as streetlamps are no longer visible over a certain distance, the continuous illumination signal is no longer generated. The distance measurement is started as soon as a streetlamp is no longer visible. If distance d traveled is greater than a predefined maximum distance without illumination, the signal is no longer generated. As soon as at least one streetlamp once again appears in the image, the distance measurement is stopped (and reset).

(39) If the yaw rate of the vehicle is excessively high, the distance measurement is stopped (paused). The reason is that for a high yaw rate, there are many changes in the camera image, and it is possible that streetlamps may no longer be recognized. Additionally or alternatively, the curve radius may be evaluated and/or the steering angle together with the speed may be evaluated (on the basis of which the yaw rate may once again be deduced). Upon travel into a continuously illuminated area, a threshold for the yaw rate could likewise be used to generate the continuous illumination signal as quickly as possible, if needed.

(40) When it is recognized that the vehicle has left the continuously illuminated area, an error is possible (for example, for an urban intersection having obscured streetlamps), and the high beam would be erroneously switched on. If the method had ended up in the no illumination state, the entire distance through the illuminated area would have to be traveled with the high beam switched on. Therefore, an indeterminate state 416 (uncertain state) is initiated in which there is a concern that the absence of illumination has been incorrectly recognized. The continuous illumination signal is not generated in state 416 (high beam is possible). However, as soon as an individual streetlamp appears, a switch is immediately made into state 406 (illumination), and continuous illumination signal 410 is once again generated. In principle, similar debouncing behavior may be achieved without state 416 when the debouncing distance is appropriately increased (for example, total of d6+d7). State 416 is used, since in this way the distance until enabling the high beam may be shortened. Debouncing distance d6 is usually sufficient. Only in a few cases is it necessary to switch back to continuous illumination within d7. Switching back via the regular path (traveling into a continuously illuminated area) normally takes longer than switching back within distance d7 of state 416.

(41) It is also possible to evaluate the distance from the streetlamps which is estimated by VDD so that, for example, crosswalks provided with multiple lights are not classified as continuous roadway illumination. The risk of erroneous detection may be reduced by recognizing traffic lights and/or intersections, since these could also be recognized as streetlamps by VDD. The visibility distance may additionally be combined via a minimum visibility duration (time) and/or a maximum visibility duration (time; for example, for streetlamps located far away) in order to improve the reliability of the detection. As a result, continuous roadway illumination which has been recognized as such only very briefly may be discarded.

(42) Likewise, continuous roadway illumination which has been mistakenly recognized (far away, away from the roadway) may be reset if it has been recognized for a fairly long time but there is no approach to an illuminated area. Upon leaving the continuous illumination, the brightness of the surroundings may be included, or the brightness level in the area ahead of the vehicle may be taken into account. The brighter the surroundings, the longer the debouncing distance, and beginning at a certain brightness level the distance measurement is paused.

(43) The brightness level in the field of expansion (the image area toward which the vehicle is traveling at that moment) may also be evaluated. By utilizing further sensors such as distance sensors, an approach to a (T) intersection may be recognized, and the debouncing time may be adapted accordingly and/or the measurement may be paused. When lane information is evaluated, the course of the roadway may be detected in an anticipatory manner. If the range of visibility on the roadway is high but no streetlamp is visible, the vehicle is traveling out of a continuously illuminated area. Likewise, the brightness of the surroundings/brightness on the roadway upon traveling into a continuously illuminated area may be utilized to shorten the debouncing distance (brightness level high) or to extend the debouncing distance (brightness level low), or to even completely prevent the debouncing distance (no change in brightness, for example because the light source is far away or away from the roadway).

(44) The minimum number for recognizing the continuous roadway illumination may be a function of speed. In this way, at high speeds the situation may be prevented that the continuous roadway illumination signal is output for two, for example, laterally situated streetlamps on a freeway, which may actually be meaningful at a low speed (the travel time between two streetlamps increases with decreasing speed). Due to the high speed, freeways having continuous roadway illumination are then recognized as continuous roadway illumination only after a relatively large number of streetlamps. The debouncing distances may be selected as a function of speed, resulting in a distance dependency as well as a certain time dependency. For example, at a high speed the debouncing distances may be increased, since in that case streetlamps do not have to be as close together. The (estimated) height of a streetlamp may be incorporated into the debouncing distance, since on account of geometry, high streetlamps are able to illuminate a larger area than low streetlamps, which has the effect of a larger detection distance (for geometric obscuration). Streetlamps which disappear from the image too far from the side of the vehicle are not taken into account, since they do not contribute to the roadway illumination. Similarly, instead of the measured/estimated distance, the height in the image (viewing angle) at which the streetlamp disappears from the image may be evaluated. The camera may be assisted by other sensors. For example, the streetlamp poles may be included in the evaluation using a LIDAR/radar system.

(45) The continuous illumination signal (roadway illumination signal S) may be used for switching to low beam, or in general for changing the light distribution. The continuous illumination signal together with the vehicle speed, for example, may likewise be used to generate a city signal. The city signal may be used, for example, to set a special city light distribution. The city signal may be checked for plausibility via navigation information, or vice versa (for example, to check the up-to-dateness of map data). In addition to the continuous illumination signal, an approach to a continuous illumination signal (approach signal) may be generated. In this case, instead of active switching to low beam as with the continuous illumination signal, switching to high beam is prevented (since switching to low beam will take place shortly afterward). The approach signal is generated as soon as streetlamps are visible (optionally with prior checking of the distance and/or position). The approach signal prevents switching to full high beam to avoid having to rapidly switch back and forth between low beam and high beam, for example, when a continuously illuminated area is approached (comfort function). The illumination range should not be additionally reduced for the approach signal. It should also be possible to slightly increase the illumination range, whereby the increase should not be great enough that a reduction of the increased light distribution due to a subsequent response to a continuous illumination signal results in sacrifices in comfort (avoiding sacrifices in comfort due to rapid switching from high beam to low beam). The generated signals (city signal, continuous illumination signal, and approach signal) may be communicated to other vehicles (optionally via a Car2x intermediary/infrastructure). After exchanging the information with two other vehicles, the vehicles may then make a 2-out-of-3 decision, for example (in general, an x-out-of-y decision). The signals of the vehicles may also be combined with one another: When an oncoming vehicle exchanges a continuous illumination signal (or leaving continuous illumination signal), the debouncing distance for traveling into a continuously illuminated area may be shortened, or an approach signal may be directly generated.

(46) In other words, the approach presented here utilizes a distance measurement of a distance covered by the vehicle. In addition, a number, a distance, and an (image) position of roadway illumination units are used to adapt a debouncing distance. A yaw rate of the vehicle (optionally, a curve radius) may be used. An indeterminate state (uncertain state) may be initiated to be able to quickly correct an error. An approach signal may be generated to prevent switching to high beam before traveling into a continuously illuminated area. Not all features are mandatory. For example, depending on the system design, the uncertain state, etc., may be dispensed with.

(47) The recognition described herein does not (or does not necessarily) switch on city light; rather, it provides a signal which allows switching to low beam or prevents switching to high beam. A change in the debouncing distance is taken into account as a function of the position/movement of the streetlamps in the image. The recognition of continuous roadway illumination may be carried out in an anticipatory manner; passing-by and distance measuring is not necessary. If the streetlamps are far at the top in the image and move quickly enough (optional), the vehicle is traveling into the illuminated area (streetlamp is very close).

(48) In the indeterminate state (uncertain state), after an unilluminated area has been recognized from an illuminated area (a city, for example), for a certain distance the debouncing distance is set to zero meters. The signal for the continuous roadway illumination is thus immediately reset as soon as a streetlamp appears in the image. The indeterminate state (uncertain state) is a follow-up function, the signal for continuous roadway illumination already having been cancelled and the city signal (which in general may also be understood to mean roadway illumination signal S) no longer being maintained. In conjunction with a recognized roadway illumination which is signaled by the roadway illumination signal, and a comparison of the vehicle speed to a speed limit, the city signal may be generated, which provides an indication that the vehicle is traveling on a roadway in a city, or in general, a developed area. For example, the city light may be switched off, and may be immediately switched back on when roadway illumination reappears.

(49) The debouncing distance is a function of the intrinsic motion (in particular the yaw rate) or changes in the image. A high rate of change in the image results in poor detection performance, causing longer debouncing times (in the extreme case, of up to infinite length). The brightness level in an (image) area, in particular the field of expansion (FOE), may also be evaluated for anticipatory plausibility checking.

(50) A distance measurement may be used to recognize a T intersection and to extend the debouncing distance for traveling out of the illuminated area (reflections of measuring signals on building walls). Estimating the range of visibility on the roadway is advantageous in order to recognize an end of the illumination in an anticipatory manner (when the roadway is straight, the range of visibility is high, and streetlamps are therefore visible early). An adaptation of the debouncing distance may thus be made. The structural height of the streetlamps may be utilized to adapt the debouncing distance (estimation of the illumination range of the streetlamp). An approach signal upon a (presumed) approach to the city/continuously illuminated area may be provided, for example, in order to not switch to high beam (but not to actively switch to low beam). Likewise, a departure signal may be provided upon the presumed departure from the illuminated area.

(51) The exemplary embodiments which are described, and shown in the figures, have been selected only as examples. Different exemplary embodiments may be combined with one another, either completely or with respect to individual features. In addition, one exemplary embodiment may be supplemented by features of another exemplary embodiment.

(52) Furthermore, method steps according to the present invention may be repeated, and carried out in a sequence different from that described.

(53) If an exemplary embodiment includes an and/or linkage between a first feature and a second feature, this may be construed in such a way that according to one specific embodiment, the exemplary embodiment has the first feature as well as the second feature, and according to another specific embodiment, the exemplary embodiment either has only the first feature or only the second feature.