JP2011178201A - Automatic lighting control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic lighting control device preventing malfunction generated by influence of noise entering an on-vehicle camera. <P>SOLUTION: This automatic lighting control device controls an irradiating part (124) of a vehicle (111) according to a light quantity state outside the vehicle (111). The automatic lighting control device includes a plurality of time constants T1 and T2, each of which shows a change rate of a luminance level in a prescribed traveling distance. The irradiating part (124) is controlled by using the time constant selected from the plurality of time constants T1 and T2 according to the light quantity state. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an auto light control device.

  Conventionally, the vehicle auto light function detects the illuminance outside the vehicle with an illuminance sensor inside the vehicle, and compares it with the threshold value for determining each light mode prepared in advance. Switch stepwise in the direction of. On the other hand, when the illuminance is lower than a threshold value of a certain light mode, the mode is switched stepwise in the direction of Auto (Low / Hi) mode to automatically determine an appropriate light mode depending on the light quantity outside the vehicle.

  On the other hand, instead of using an illuminance sensor for the vehicle's autolight function, an image in front of the vehicle is taken using a camera mounted in the vicinity of the interior mirror in the vehicle, and the brightness value around the vehicle is calculated from the image data to determine the light mode. There is an apparatus that performs (see, for example, Patent Document 1).

JP 2008-110715 A

  In the conventional method, the luminance value transferred to the auto light unit is used as it is, and the light mode is determined. However, the brightness value transferred to the auto light unit has an influence on an image taken from the imaging unit, such as an obstacle or an unintended scene. Obstacles entering the image from the imaging unit and unintended scenes are as follows. In-vehicle cameras are affected by cars moving at high speed, and are affected by dirt and characters on the road surface, shadows under buildings and overpasses, walls, and leading vehicles. As a result, the brightness value changes drastically for a moment, causing malfunction of the auto light mode.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an auto light control device that prevents malfunction caused by the influence of noise entering an in-vehicle camera.

  The auto light control device of the present invention that solves the above-described problem has a plurality of time constants indicating the rate of change of the luminance value at a predetermined travel distance, and a time constant selected from the plurality of time constants according to the light quantity situation The irradiation unit is controlled using.

  According to the automatic light control device of the present invention, the automatic light function that prevents a malfunction of the automatic light mode due to abrupt environmental conversions and unintended effects that occur while the vehicle is running is more accurate than a conventional illuminance sensor. Can be realized. Furthermore, the conventional illuminance sensor is not necessary only for vehicles equipped with a vehicle-mounted monocular camera, and cost performance can be improved.

1 is a functional block diagram of an auto light control device according to the present embodiment. The flowchart explaining the processing content of the auto light part shown in FIG. The flowchart explaining the content of the process in step S100 of FIG. The figure which shows the hysteresis value which determines write mode. The flowchart explaining the selection method of a time constant. The flowchart explaining the content of the time constant filter process. The block diagram which shows the content of the time constant filter process. The graph figure which shows the change of the luminance value and each time constant filter value during driving | running | working. The flowchart explaining the content of the selection element calculation process. The flowchart explaining the content of the time constant selection process. The graph which shows the change of the filter result value by each time constant filter means. The flowchart explaining the content of the light mode determination process. The flowchart explaining the content of the light mode determination process. The flowchart explaining the content of the light mode determination process. The flowchart explaining the content of the light mode determination process. The figure which shows the content of each conditional sentence used for FIGS. 12-15.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an in-vehicle camera (110) related to the autolight control device, a vehicle controller (123) for controlling the vehicle (111) based on information from the in-vehicle camera (110), and a headlamp / tail lamp (124). .

  The in-vehicle camera (110) includes an imaging unit (112) and an image processing unit (113) .The imaging unit (112) includes a lens (114) and a CMOS device (115), and the image processing unit (113) An exposure control unit (116) that controls the CMOS device (115) using the captured image, a luminance value estimation unit (117) that estimates the luminance value of the image based on data from the exposure control unit (116), image processing A pedestrian detection unit (118), a vehicle detection unit (119), a lane detection unit (120), a light distribution control unit (121), and an auto light unit (122).

  The in-vehicle camera (110) is mounted near the rear-view mirror in the passenger compartment, captures a front image of the vehicle, performs image processing, and transfers the result to the vehicle controller (123) of the vehicle (111). 111) can be controlled.

  The parts related to the auto light control device according to the present invention include an imaging unit (112), an exposure control unit (116), a luminance value estimation unit (117), a light distribution control (121), an auto light unit (122), and a vehicle side controller. (123) is a head lamp and tail lamp (124).

  The lens (114) and the CMOS device (115) of the imaging unit (112) are a pedestrian detection unit (118), a vehicle detection unit (119), a lane detection unit (120), a light distribution control unit (121), an auto light. An image tailored to each application unit such as the unit (122) is acquired.

  The exposure control unit (116) calculates an average density value of a specific portion of the image using the image captured by the imaging unit (112), and the imaging unit (112) captures a constant image. The CMOS device (115) of the unit (112) is controlled. An item necessary for controlling the CMOS device 115 is an exposure value, and this exposure value is constituted by a shutter, gain, gamma, and HDR (high dynamic range).

  The luminance value estimation unit (117) can estimate the luminance value based on the exposure characteristic and the exposure value obtained from the CMOS device (115), and the luminance value is almost equal to the result value measured by the luminance meter. It is the same, and comprises a luminance value detection means.

  The auto light unit (122) performs calculation related to auto light control based on the luminance value, and transfers the result value of the vehicle light mode to the light distribution control unit (121) and the vehicle side controller unit (123). The light distribution control unit (121) determines ON / OFF switching of the light distribution control operation based on the result sent from the auto light unit (122).

  The vehicle controller (123) of the vehicle (111) sets the light mode of the headlamp / tail lamp (124), which is the irradiation unit of the vehicle, to Off, Small, Low, Auto according to the result from the auto light unit (122). Select from.

FIG. 2 is a flowchart for explaining processing contents of the auto light unit shown in FIG.
When the auto light unit (122) receives the luminance value from the luminance value estimation unit (117), parameters necessary for the calculation of the auto light unit (122) are set according to the situation of the in-vehicle camera (110). Then, the first time constant filter processing (S200), the second time constant filter processing (S300), the selection element calculation processing (S400), and the time constant selection processing (S500), which are characteristic configurations of the present invention, are performed. Subsequently, auto light mode determination processing (S600) and auto light mode transfer processing (S700) are performed.

  The process (S200 to S500) newly added in the present invention prevents malfunction that is a problem of the conventional method. In the conventional method, the luminance value transferred to the auto light unit (122) is used as it is, and the process of selecting the light mode according to the luminance value is performed.

  However, the image taken by the imaging unit (112) shows obstacles and unintended scenes, etc., which also affects the luminance value transferred to the auto light unit (122). Will change drastically for a moment, causing the auto light mode to malfunction. Obstacles and unintended scenes appearing in the image taken by the imaging unit (112) are as follows, for example. The in-vehicle camera (110) is affected by dirt and characters on the road surface, shadows under buildings and overpasses, walls, and leading vehicles due to the influence of a vehicle moving at high speed.

  Therefore, in the present invention, for the purpose of preventing malfunction, the first time constant filter processing (S200), the second time constant filter processing (S300), the selection element calculation processing (S400), and the time constant selection processing (S500). Add The result value calculated in each newly added process (S200 to S500) is converted to an auto light mode value in auto light mode determination (S600), and the mode value is converted to the light distribution control unit (121) and the vehicle (111 ) To the vehicle controller (123), the auto light unit (122) ends.

  The auto light unit (122) sets the head lamp / tail lamp (124) mode to OFF for about 0.5 seconds after the power of the in-vehicle camera (110) is turned on. The reason is that the auto light unit (122) is processed based on the brightness value, but it takes about 0.5 seconds until the in-vehicle camera (110) is turned on and the brightness value is stabilized. Because it becomes.

  FIG. 3 is a flowchart for explaining the contents of the initialization process in step S100 of FIG. In the flowchart of FIG. 3, first, the luminance value transferred from the luminance value estimation unit (117) is converted into a Log value (S101). Since the luminance value becomes the Log value, the calculated result values can be compared. Then, in the next stage, it is determined whether or not it is the first initialization after the on-vehicle camera (110) is activated (S102).

  Here, in the case of the first initialization (YES in S102), a hysteresis value necessary for determining the auto light mode is set from the calculated luminance value (S103). FIG. 4 is a diagram showing hysteresis values for determining the write mode. The horizontal axis in FIG. 4 is the luminance value, and the vertical axis is the light mode. This hysteresis value is a value determined by performing an experiment for comparison with an illuminance sensor currently used and further considering a luminance change value for a road surface character that causes hunting in the light mode. In the last process of initialization (S100), the result value calculated by the previous auto light unit (122) is stored as a past value (S104). The write mode can be quickly determined based on the past value.

  FIG. 5 is a flowchart for explaining the characteristic part of the processing content of the auto light unit. In the flowchart of FIG. 5, the first time constant filter process (S200), the second time constant filter process (S300), the selection element calculation process (S400), and the time constant selection process (S501, S502) will be described.

  First, a first time constant filter process (S200) and a second time constant filter process (S300) are performed on the luminance values that have been initialized in the previous stage of FIG. In this embodiment, the first time constant filter process (S200) is performed first, and then the second time constant filter process (S300) is performed as an example. However, the first time constant filter process is performed. The order of (S200) and the second time constant filter process (S300) is not limited to the order of the present embodiment, and the second time constant filter process may be performed first. The time constant filtering process (S200) and the second time constant filtering process (S300) may be performed simultaneously.

  The purpose of performing the first time constant filtering process (S200) and the second time constant filtering process (S300) is to prevent malfunctions that occur in conventional autolight control. The in-vehicle camera (110) mounted on a car that moves at a high speed is susceptible to noise elements such as dirt and characters on the road surface, shadows under buildings and overpasses, walls, and leading vehicles.

  Due to various noise elements entering the in-vehicle camera (110), the luminance value is changed drastically for a moment, and there is a possibility that a malfunction of auto light control may occur according to the change. Therefore, in the present invention, the first time constant filtering process (S200) and the second time constant filtering process (S300) are performed on the luminance value, and further selected from the results of the two time constant filtering processes. By determining the light mode with one result value, it is possible to perform stable and quick auto light control that is not affected by noise elements entering the in-vehicle camera (110).

  FIG. 6 is a flowchart for explaining the contents of the time constant filter process. In the first step of the time constant filter process, initialization confirmation (S201) is performed. If the first filter process is performed after the vehicle-mounted camera (110) is activated, the initialization process is performed. In the initialization process, a time constant setting process (S202) and an array initialization process (S203) for storing the time constant filter result value are performed. When the initialization inside the time constant filter is completed, a filter calculation process for calculating the time constant filter is performed (S204). In the last step, the time constant filter result value calculated in the filter calculation process is converted into a candela value (cd), which is the original luminance value unit, and stored (S205).

FIG. 7 is a block diagram showing the contents of the time constant filter processing. The first time constant filter (first time constant filter means) 210 that performs the first time constant filter processing, and the second time constant. A second time constant filter (second time constant filter means) 310 that performs filter processing is shown. The control contents of the first time constant filter 210 and the second time constant filter 310 shown in FIG. 7 can be expressed by equations (1) and (2), respectively.
Y1 = L × T1 + ((Y1 ′ × (1-T1)) ... Formula (1)
Y2 = L × T2 + ((Y2 ′ × (1-T2)) ... Formula (2)

  Here, L in Equation (1) and Equation (2) is the luminance value input to the time constant filter 1, T1 is the time constant 1, T2 is the time constant 2, Y1 'is the time constant filter 1 previously calculated. The result value Y2 ′ is the result value of the time constant filter 2 calculated last time.

  The time constants T1 and T2 are adjustment parameters that determine the characteristics of the time constant filter, and indicate the change rate of the luminance value in a predetermined travel distance.

  In this embodiment, the time constant T1 of the first time constant filter (210) is set to 0.05, and the amount of change is smaller and the change speed is slower than the luminance value input to the first time constant filter (210). Ask for results.

  On the other hand, the time constant T2 of the second time constant filter (310) is set to 0.5, and the luminance value input to the second time constant filter (310) is set by the second time constant filter (310). The filter result value calculated and output is obtained with the same change amount and the same change speed. The parameter settings for the time constant T1 and the time constant T2 take into consideration the results of public road experiments and simulations.

Next, the result of the time constant filter with respect to the luminance value will be described with reference to FIG.
FIG. 8 is a graph showing changes in the luminance value and each time constant filter value during travel, and is a graph showing the change in the brightness value of an in-vehicle camera mounted on a car traveling during a clear daytime. .

  The horizontal axis of the graph is distance, and the vertical axis is luminance value (cd). In FIG. 8, data A indicated by a solid line is a luminance value input to the time constant filter, data B indicated by a broken line is a filter result value (first filter result value) by the first time constant filter, one point Data C indicated by a chain line represents a change in a filter result value (second filter result value) by the second time constant filter.

  A section 1 with respect to the distance in FIG. 8 represents a place where there is noise such as dirt on the road surface, characters, a shadow under a building or an overpass. The data A has a large range of change due to the influence of noise, and the possibility of causing a malfunction by auto light control increases.

  In the case of data C, the range of change is smaller than that of data A, but is almost the same. However, since data B has a smaller amount of change in luminance than data A, no malfunction occurs in auto light control.

  Sections 2 and 3 shown in FIG. 8 represent states when the vehicle enters and exits the tunnel. First, when the vehicle enters the tunnel at a high speed, the amount of light suddenly decreases and the data A similarly decreases.

  In this case, since it is necessary to quickly turn on the headlamp / tail lamp (124), the luminance value change of the data C by the second time constant filter processing (S300) almost the same as the data A is appropriate. When the vehicle leaves the tunnel, the change in the luminance value of the data C is appropriate as in the case of entering.

  In the selection element calculation process (S400), a process of calculating a selection element for selecting an appropriate filter result value according to the situation is performed (selection element calculation means).

  FIG. 9 is a flowchart for explaining the contents of the selected element calculation process. In step (S401), the maximum value and the minimum value of the first filter result value are obtained from the past values of a predetermined time set in advance as the determination time, and the change amount of the first filter result value is first selected. Calculate as an element (first selection element calculation means).

  In step (S402), the maximum value and the minimum value of the second filter result value are obtained from the past values for a predetermined time, and the amount of change in the second filter result value is calculated as the second selection factor (second selection). Selection factor calculation means).

  In step (S403), a vehicle speed average value for a predetermined time is obtained, and the moving distance of the vehicle is calculated as a third selection factor (third selection factor calculation means). In the last step (S404), the write mode is checked, and the first filter result value and the second filter result value are within the same write mode (same area) among the plurality of write modes in which the first filter result value is preset. Is determined as a fourth selection element (fourth selection element calculation means). As described above, based on the four calculation result values (the first selection element to the fourth selection element), the filter result value necessary for the automatic light mode determination is either the first filter result value or the second filter result value. Determine if there is.

  First, in the normal operation from the start of the in-vehicle camera (110), the light mode is determined based on the first filter result value. As described above, the malfunction of auto light control can be prevented from noise by using the first filter result value as a basis.

  However, when entering the tunnel, it is necessary to quickly turn on the head lamp and tail lamp (124) by auto light control. In this case, it is necessary to determine the light mode based on the second filter result value. Then, after exiting the tunnel, it is necessary to restore the setting so that the write mode is determined based on the first filter result value as usual.

  FIG. 10 is a flowchart for explaining the contents of the time constant selection process. Here, based on the first to fourth selection elements calculated by the selection element calculation means, a process of selecting one of the first filter result value and the second filter result value is performed (selection). means).

Conditional statement 1 (first condition) in step S501 of FIG. 10 and conditional statement 2 (second condition) in step S502 can be expressed by the following equations (3) and (4).
Conditional statement 1: (first selection element <0.02) AND (satisfies fourth selection element) Expression (3)
Conditional statement 2: (second selection element> 1) AND (third selection element <30m) (4)
Here, the first to fourth selection elements are those described in the description of FIG. 9, and the fourth selection element in the formula (3) satisfies the fourth selection element when present in the same region. It is judged that

  Expression (3) is an expression for determining whether to switch from the first filter result value to the second filter result value for auto light control. Expression (4) is an expression for determining whether to switch from the second filter result value to the first filter result value for auto light control.

  In the time constant selection process, as shown in FIG. 10, it is determined whether or not the conditional statement 1 is satisfied (S501), and when satisfied, the first filter result value is selected (S503). Then, when the conditional statement 1 is not satisfied, it is determined whether or not the conditional statement 2 is satisfied (S502). Here, when the conditional statement 2 is satisfied, the second filter result value is selected (S504), and when the conditional statement 2 is not satisfied, the current filter result value is not changed and a process without change is performed (S505). ).

  Here, the expressions (3) and (4) will be described with reference to FIG. 8. In the section 1 of FIG. 8, the first time constant filtering process (S210) performs the first operation as usual. Auto light control is performed using the filter result value.

  However, when entering the tunnel from Section 1 to Section 2, it is necessary to turn on the headlamp / taillamp (124) early to ensure the driver's view. Therefore, the amount of change in the second filter result value, which is the second selection element of Equation (4), exceeds 1, and the scene occurs within 30 m, which is the moving distance of the vehicle determined from the third selection element. It is determined that it has entered the tunnel.

  Then, by switching from the first filter result value to the second filter result value, auto light control is performed with the second filter result value, and the headlamp / tail lamp (124) can be quickly turned ON.

  After that, when running through a long tunnel or exiting the tunnel, the amount of change in the first filter result value, which is the first selection element of Equation (3), is 0.02 or less, and the fourth selection element If a certain first filter result value and a second filter result value are in the same region of the write mode, auto-light control is performed with the normal first filter result value, and stable control becomes possible. .

  The fourth selection element in Equation (3) is used to prevent a malfunction of the auto light operation. Next, the problem of the auto light operation will be described with reference to FIG.

  FIG. 11 is a graph at the time of leaving the tunnel. Data A indicated by a broken line and data B indicated by a two-dot chain line represent a first filter result value and a second filter result value. A line a` shown in FIG. 11 represents the upper limit value of hysteresis when the write mode is switched from Small to Off.

  The auto light unit (122) performs auto light control using the data A up to the distance b` shown in FIG. 11, but from b`, the time constant selection processing (S500 ) To perform auto light control using data B. When the data B exceeds the threshold value of the line a`, the auto light mode is switched from Small to OFF.

  However, when the data A is stable near the threshold value of the line a`, the time constant selection process switches to the automatic light judgment using the data A, but the data A can be stabilized without exceeding the threshold value of the a`. If the auto light mode is determined in this situation, the auto light mode is changed from Off to Small due to the influence of data A, and hunting occurs between Small and OFF.

  Therefore, in the fourth selection element, the replacement of the time constant filter result is permitted only when the first filter result and the second filter result are in the same write mode region, thereby preventing the occurrence of hunting. .

  12 to 15 are flowcharts for explaining the content of the write mode determination process, and FIG. 16 is a diagram illustrating the content of each conditional statement used in FIGS. 12 to 15. When the hysteresis value that determines the auto light mode changes with respect to the previous auto light control result, the auto light mode estimation method shown in FIGS. 12 to 15 quickly responds even when the auto light mode changes to the width. It becomes possible to do.

  In FIG. 12, first, the selected filter result value and the previous light mode are entered as input values for the auto light mode estimation of FIG. As the first determination element, it is confirmed whether the previous write mode is Auto or not (No), it is transferred to A of FIG. On the other hand, if it is positive (Yes), it is input to the conditional statement 1 in FIG. 16 and it is determined whether the selected filter result value is larger than 6 (cd). If it is positive (Yes), Auto is output as the final write mode.

  If the conditional statement 1 is negative (No), the conditional statement 2 is entered, and it is determined whether the filter result value selected by the conditional statement 2 in FIG. 16 is greater than 60 (cd). If condition statement 2 is positive (Yes), Low is output as the final write mode. If the conditional statement 2 is negative (No), the conditional statement 3 is entered, and it is determined whether the filter result value selected by the conditional statement 3 in FIG. 16 is greater than 200 (cd). If conditional statement 3 is positive (Yes), Small is output as the final write mode.

  If the last conditional statement 3 is NO (No), Off is output as the final write mode. 13, 14, and 15, the filter result value selected in the same manner as in FIG. 12, the previous write mode, Low, Small, and Off modes, and the conditions of FIGS. 13, 14, and 15. The light mode is estimated and switched instantly from Auto to Off based on the sentence.

  The contents for the conditional statements 1 to 12 in FIGS. 12 to 15 are shown in a table in FIG. The conditional statement makes a determination by comparing the filter result value with the hysteresis value of each auto light mode (light mode determination means). The result value of the auto light mode determined finally is transferred to the light distribution control unit (121) and the vehicle controller (123) of the vehicle (111).

  The light distribution control unit (121) determines ON / OFF of the light distribution control operation based on the result value of the transferred auto light mode. The auto light mode result value transferred to the vehicle controller (123) of the vehicle (111) is used to control the mode of the headlamp / tail lamp (124).

  According to the auto light control device of the present invention, there are a plurality of time constants indicating the change rate of the luminance value at a predetermined travel distance, and the time constant selected from the plurality of time constants according to the light quantity situation is used. Controls the irradiating unit, preventing abrupt environmental changes that occur while the vehicle is running and the effects of unintended objects to prevent malfunctions in the auto light mode, and to realize more accurate auto light functions than conventional illuminance sensors I can do it. Furthermore, the conventional illuminance sensor is not necessary only for vehicles equipped with a vehicle-mounted monocular camera, and cost performance can be improved.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

114… Lens
115… CMOS device
116… Exposure control unit
117… Brightness value estimation unit
118… Pedestrian detection unit
119… Vehicle detector
120… Lane detection part
121… Light distribution controller
122… Auto light section
123… Vehicle controller
124… Head lamp and tail lamp

Claims (5)

An automatic light control device that controls an irradiation unit of a vehicle according to a light amount condition outside the vehicle,
A plurality of time constants indicating a rate of change in luminance value at a predetermined travel distance, and the irradiation unit is controlled using a time constant selected from the plurality of time constants according to the light quantity situation. Auto light control device to do. A luminance value detecting means for detecting a luminance value in front of the vehicle;
First time constant filter means for calculating a first filter result value from the luminance value using a first time constant;
Second time constant filter means for calculating a second filter result value from the luminance value using a second time constant;
Selection element calculation means for calculating a selection element for selecting one of the first filter result value and the second filter result value based on the first filter result value and the second filter result value; ,
Selection means for selecting one of the first filter result value and the second filter result value based on the selection element calculated by the selection element calculation means;
Light mode determination means for determining the light mode of the irradiation unit using the filter result value selected by the selection means,
2. The automatic light control apparatus according to claim 1, wherein the irradiation unit is controlled based on a determination result of the light mode determination means.   The selection element calculation means includes a first selection element calculation means for calculating a change amount of the first filter result value at a preset determination time as a first selection element, and a second filter result value at the determination time. A second selection element calculation means for calculating a change amount as a second selection element; a third selection element calculation means for calculating a moving distance of the vehicle at the determination time as a third selection element; and 4th selection element calculating means which determines whether it is the same write mode among several write modes with which the 1st filter result value and the 2nd filter result value were preset is the 4th selection element The auto light control device according to claim 2, wherein The selection means includes
When it is determined whether or not a first condition is satisfied that the first selection element is smaller than a preset first reference value and the fourth selection element is in the same light mode, and the first condition is satisfied Comprises first determination means for selecting the first filter result value;
When the first determination means determines that the first condition is not satisfied, the second selection element is greater than a preset second reference value and the third selection element is greater than a preset reference distance. The second filter result value is selected when the second condition is satisfied, and the current filter result value is not changed when the second condition is not satisfied. The automatic light control device according to claim 3, further comprising: a second determination unit that selects the above.   The first time constant is set so as to obtain the first filter result value at a smaller change amount and a slower speed than the luminance value, and the second time constant is obtained by calculating the second filter result value. The automatic light control device according to any one of claims 2 to 5, wherein the automatic light control device is set so as to be obtained with the same change amount and change speed as the luminance value.

Images