JP2011251600A - Device for detecting brake operation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for detecting brake operation, which reduces the number of internal wirings smaller than before.SOLUTION: The brake operation detection device 20 includes: an evaluation value obtainer 21 for obtaining data of a brightness value and intensity values of R, G, B components of a captured image from an output signal of a pre-processor 13 to set the data as each datum of an evaluation value; a threshold value determiner 22 for obtaining data of the brightness value of the captured image from the output signal of the pre-processor 13, a shutter value and a gain value set by the pre-processor 13 to dynamically determine thresholds A, B, C based on the data; and a brake operation determiner 23 for comparing a present frame evaluation value with the thresholds A, B to determine whether the lighting of a brake lamp is detectable, and also when the lighting of the brake lamp is detectable, determining whether an absolute value of a difference between frame evaluation values is equal to or larger than the threshold C.

Description

  The present invention relates to a brake operation detection device that detects a driver's brake operation using an output signal of an in-vehicle imaging device that images the outside of a vehicle.

  Conventionally, as a method of detecting a driver's brake operation using an output signal of an in-vehicle imaging device, a brake operation of a preceding vehicle is detected by detecting lighting of a brake lamp of a preceding vehicle from a captured image in front of the host vehicle. A collision prevention device is known (see, for example, Patent Document 1).

  Patent Document 1 discloses a means for calculating distance distribution information by processing an image captured by a CCD camera with an image processor, and reading the distance distribution information into a controller to obtain a three-dimensional road shape or a plurality of three-dimensional objects. Means for detecting the position and identifying the preceding vehicle; means for detecting the presence or absence of the brake lamp on the preceding vehicle from the position information of the preceding vehicle and an image captured by the CCD camera; and determining the deceleration state of the preceding vehicle; Means for determining the possibility of collision from the deceleration state of the preceding vehicle and the traveling state of the host vehicle, and displaying the result on a display, and accurately determining the possibility of collision between the preceding vehicle and the host vehicle. It can be done.

JP 11-39597 A

  However, what is disclosed in Patent Document 1 is intended to detect a brake operation of another vehicle traveling ahead, and does not detect a brake operation of the own vehicle. When it is desired to perform predetermined control in conjunction with the operation, there has been a problem that an internal wiring for transmitting a signal indicating a brake operation is required.

  Specifically, for example, when it is desired to operate the in-vehicle image pickup device in conjunction with the brake operation of the driver of the host vehicle, the conventional technique transmits a signal indicating the brake operation to the in-vehicle image pickup device. To the in-vehicle image pickup device. The wiring work of the internal wiring has a problem that it is complicated and time-consuming, and the number of wiring parts increases, which causes a cost increase.

  The present invention has been made to solve the conventional problems, and an object of the present invention is to provide a brake operation detection device capable of reducing the number of internal wirings compared to the conventional art.

  The brake operation detection device according to the present invention provides a driver's brake in a vehicle equipped with an imaging device capable of sensing a subject outside the host vehicle at a predetermined frame interval and sensing the lighting light of the brake lamp of the host vehicle. A brake operation detecting device for detecting presence or absence of an operation, wherein an inter-frame change amount of an intensity of at least one color component among a plurality of color components included in a captured image captured by the imaging device is determined in advance. It has the structure provided with the brake operation determination part which determines that the said brake operation was performed when the value was exceeded.

  With this configuration, the brake operation detection device of the present invention determines whether or not the brake operation has been performed based on the amount of change in the intensity of the color component included in the captured image captured by the imaging device. No internal wiring to the device is required. Therefore, the brake operation detecting device of the present invention can reduce the number of internal wires as compared with the conventional case.

  In addition, the brake operation detection device of the present invention includes a threshold value determination unit that dynamically determines the threshold value, and the imaging device uses an imaging element that images the subject and an output signal of the imaging element. A gain correction unit that performs gain correction on the image sensor, and an exposure control unit that determines a shutter value of the image sensor and a gain value of the gain correction unit. The threshold value determination unit includes the shutter value and the gain. The threshold value is dynamically determined based on the value and the luminance value of the captured image data output by the gain correction unit.

  With this configuration, the brake operation detection device of the present invention can detect whether the brake lamp is turned on or off according to the brightness of the subject.

  Further, in the brake operation detection device of the present invention, the threshold value determination unit determines the brightness of the subject based on the shutter value, the gain value, and the brightness value of the data of the captured image output by the gain correction unit. And the brake operation determining unit stops detecting the brake operation when the threshold value determining unit recognizes that the brightness of the subject is outside a predetermined range. It has a configuration.

  With this configuration, the brake operation detection device of the present invention stops detecting the brake operation when the subject is darker or brighter than the predetermined brightness, and prevents erroneous detection when the subject is too dark or too bright. can do.

  Furthermore, in the brake operation detection device of the present invention, the threshold value determination unit includes a first threshold value for determining whether or not the brake operation is performed in a direction in which the intensity of the at least one color component increases, and the at least one value. And a second threshold value for determining the presence or absence of the brake operation in a direction in which the intensity of one color component decreases.

  With this configuration, the brake operation detection device of the present invention can determine whether or not a brake operation is performed even when the amount of change between frames of the intensity of a specific color component differs between when the brake lamp is turned on and when the brake lamp is turned off.

  Furthermore, in the brake operation detection device of the present invention, the brake operation determination unit is configured such that, in an image obtained by dividing the captured image captured by the imaging device into a plurality of blocks, the intensity of the at least one color component among the plurality of blocks. When there is a block in which the amount of change between frames exceeds the threshold value, it is determined that the brake operation has been performed.

  With this configuration, the brake operation detection device of the present invention can detect the brake operation based on the amount of change in the intensity of the color component of the predetermined block.

  In addition, with this configuration, the brake operation detection device of the present invention is less affected by the lighting and extinguishing of the brake lamp in a range where the distance from the imaging device to the subject is relatively far, so the distance from the imaging device to the subject is compared. It is possible to detect the brake operation based only on the change amount of the intensity of the color component only in the captured image block corresponding to the close range.

  The present invention can provide a brake operation detecting device having an effect that the number of internal wirings can be reduced as compared with the prior art.

The block block diagram of the brake operation detection system in one Embodiment of this invention The flowchart of the brake operation detection apparatus which the brake operation detection system in one Embodiment of this invention has

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the configuration of the brake operation detection system in the present embodiment will be described.

  As shown in FIG. 1, the brake operation detection system 1 in this embodiment includes an imaging device 10 and a brake operation detection device 20.

  The imaging device 10 includes a lens unit 11, an imaging element 12, a preprocessing unit 13, an exposure control unit 14, a drive processing unit 15, and a signal processing unit 16, and images a subject at a predetermined frame interval. Yes. The image pickup apparatus 10 can pick up an image of a subject outside the host vehicle and can sense lighting light of a brake lamp of the host vehicle. For example, the imaging device 10 is a digital video camera for a back monitor that captures the rear of the host vehicle, and is installed between the left and right brake lamps, and directly or indirectly emits light from the brake lamps of the host vehicle. It has a perceivable configuration. Here, as an example of indirectly detecting the lighting light of the brake lamp, there are detection by reflected light from a road relatively close to the own vehicle, reflected light from a garage wall when the own vehicle enters the garage, etc. is there.

  The lens unit 11 condenses the light of the subject and forms an image of the subject on the imaging surface of the image sensor 12.

  The image sensor 12 captures an image of a subject formed by the lens unit 11 and generates a captured image of the subject. The imaging element 12 is configured by, for example, a CCD (Charge Coupled Device), includes photodiodes arranged in a matrix on the imaging surface, and pixels are configured by the respective photodiodes. The image sensor 12 includes a different color filter for each pixel, and outputs an analog signal dispersed by these color filters. In this configuration, when the imaging device 12 includes, for example, a visible light filter that transmits red, green, and blue light, the intensity of the visible light component included in the subject can be obtained. Note that the imaging device 12 may be a CMOS (Complementary Metal-Oxide-Semiconductor) type imaging device.

  The preprocessing unit 13 includes, for example, a correlated double sampling circuit, an automatic gain correction circuit, an AD converter circuit, and the like. The correlated double sampling circuit removes noise from the captured image generated by the image sensor 12. The automatic gain correction circuit automatically performs gain correction on the signal from the correlated double sampling circuit. The AD converter circuit converts an analog signal from the automatic gain correction circuit into a digital signal.

  The exposure control unit 14 calculates the exposure amount of the image sensor 12 based on the captured image data digitized by the preprocessing unit 13. Then, according to the calculated exposure amount, the exposure control unit 14 controls the drive processing unit 15 such as adjusting the shutter value, and controls the preprocessing unit 13 such as adjusting the gain value. ing. By providing this exposure control unit 14, the imaging apparatus 10 can perform automatic exposure (AE) control.

  The drive processing unit 15 includes a vertical transfer drive circuit, a timing generator circuit, and the like. The drive processing unit 15 adjusts the shutter value according to the control of the exposure control unit 14 and drives the image sensor 12.

  The signal processing unit 16 performs signal processing for generating a video signal on the digital signal AD-converted by the preprocessing unit 13. For example, the signal processing unit 16 mainly performs luminance signal generation, color signal generation, and aperture signal generation, and for other general video such as OB (Optical black) subtraction, white balance adjustment, and noise reduction. This signal processing can also be performed.

  The brake operation detection device 20 includes an evaluation value acquisition unit 21, a threshold value determination unit 22, and a brake operation determination unit 23. When the brightness of a subject imaged by the imaging device 10 is within a predetermined range, the imaging device The brake operation is detected based on the ten captured images.

  The evaluation value acquisition unit 21 outputs the intensity value data of the captured image, the intensity value of the red component (R component), the green component (G component), and the blue component (B component) from the output signal of the preprocessing unit 13 for each frame. To get. Here, for example, the evaluation value acquisition unit 21 obtains the intensity values R, G, and B of each of the RGB components, and calculates the luminance value using a formula of luminance value = (R + 2G + B) / 4. Further, the evaluation value acquisition unit 21 outputs the acquired data to the brake operation determination unit 23 as evaluation value data for determining the presence or absence of a brake operation.

  The evaluation value acquisition unit 21 may acquire each piece of evaluation value data for each pixel constituting the captured image, or may be configured to acquire the captured image for each block by dividing the captured image into a plurality of blocks. . Further, the evaluation value acquisition unit 21 may acquire, for example, intensity value data of only the R component that is the main component of the brake lamp light.

  The threshold value determination unit 22 acquires the luminance value of the captured image for each frame from the output signal of the preprocessing unit 13. For example, the threshold value determination unit 22 calculates a luminance value from the intensity values R, G, and B of each RGB component using the above-described formula for calculating the luminance value. Further, the threshold value determination unit 22 acquires the shutter value and gain value data set by the preprocessing unit 13 for each frame. The threshold value determination unit 22 recognizes the brightness of the subject imaged by the imaging device 10 from the luminance value, shutter value, and gain value of the captured image in the current frame.

  Further, the threshold value determination unit 22 sets the threshold values A and B for determining whether or not the brightness of the subject is in a predetermined range, the brightness value of the captured image in the current frame, the shutter value, It is determined dynamically according to the gain value. The threshold values A and B determine the lower limit value and the upper limit value of the brightness of the subject, and are individually determined for the luminance value, R component, G component, and B component of the captured image. By the determination based on the threshold values A and B, the brake operation detection device 20 stops detecting the brake operation when the subject is darker or brighter than the predetermined brightness, and the subject is too dark or too bright. False detection can be prevented.

  Further, the threshold value determination unit 22 recognizes the brightness of the subject from the brightness value, shutter value, and gain value of the captured image in the current frame, and determines whether or not the brake lamp is turned on according to these values. The threshold value C for determination based on the amount of change in the evaluation value is dynamically determined. With this threshold C, it is possible to detect whether the brake lamp is on or off without being affected by the brightness of the subject. For example, the threshold value determination unit 22 determines the threshold value C to be smaller as the subject is brighter, and determines the threshold value C to be larger as the subject is darker.

  Note that the dynamic determination method of the threshold values A, B, and C can be determined in advance by experiments, simulations, or the like according to the brightness of the subject.

  The brake operation determination unit 23 determines whether the driver of the vehicle brakes based on the evaluation value data acquired by the evaluation value acquisition unit 21 and the threshold values A, B, and C determined by the threshold value determination unit 22. It is determined whether or not an operation has been performed.

  Specifically, the brake operation determination unit 23 first determines whether it is possible to detect the lighting of the brake lamp. That is, the brake operation determination unit 23 determines the brightness value, R component, G component, and B component evaluation values (hereinafter referred to as “current frame evaluation values”) of the captured image of the current frame, and threshold values A and B. In comparison, it is determined whether or not the brake lamp can be detected. For example, the brake operation determination unit 23 determines that the subject is too dark when the current frame evaluation value is less than the threshold value A, and does not determine whether or not the brake operation is performed. The brake operation determination unit 23 determines that the subject is too bright when the current frame evaluation value is greater than the threshold value B, and does not determine whether or not the brake operation is performed. In other words, the brake operation determination unit 23 determines whether or not the brake operation is performed when the current frame evaluation value is not less than the threshold value A and not more than B.

  Further, when the brake operation determination unit 23 determines that the lighting of the brake lamp can be detected, the brake operation determination unit 23 determines the presence or absence of the brake operation based on the amount of change in the evaluation value between frames.

  Specifically, the brake operation determination unit 23 determines the difference between the current frame evaluation value and the evaluation value of the frame immediately before the current frame (hereinafter referred to as “previous frame evaluation value”) (hereinafter “interframe evaluation value”). When the absolute value of “difference” is smaller than the threshold value C, it is determined that the brake operation is not performed. On the other hand, when the absolute value of the inter-frame evaluation value difference is larger than the threshold value C, the brake operation determination unit 23 determines that the brake operation has been performed.

  The brake operation determination unit 23 is configured such that the evaluation value acquisition unit 21 divides the captured image into a plurality of blocks and acquires each piece of evaluation value data for each block. A configuration may be adopted in which it is determined that a brake operation has been performed when there is a block in which the amount of change in the block average strength between frames exceeds the threshold value C. With this configuration, the brake operation determination unit 23 is not easily affected by the lighting or extinguishing of the brake lamp in a range where the distance from the imaging device 10 to the subject is relatively long (for example, the sky or a distant building). The brake is performed based on the intensity change amount of a predetermined color component only in a block of a captured image corresponding to a range in which the distance from the subject 10 to the subject is relatively close (for example, a portion of a road close to the host vehicle or a garage wall). Operation detection can be performed.

  Further, by separately setting the threshold value C in the direction in which the intensity of the specific color component increases and in the direction in which the intensity of the specific color component decreases, the amount of change between frames of the intensity of the specific color component is Even when it is different from when it is turned off, the brake operation determination unit 23 can determine when the brake lamp is turned on and when it is turned off.

  Next, operation | movement of the brake operation detection system 1 in this embodiment is demonstrated using FIG. FIG. 2 is a flowchart showing the operation of the brake operation detection device 20 in the brake operation detection system 1. In the following description, it is assumed that the imaging device 10 images a subject while performing AE control, and outputs captured image data to the brake operation detection device 20 at a predetermined frame interval. Omitted.

  The evaluation value acquisition unit 21 acquires the brightness value, R component, G component, and B component intensity values of the captured image from the output signal of the preprocessing unit 13 for each frame, and determines whether the acquired data is a brake operation. It is set as each data of the evaluation value for determining (step S11). Further, the evaluation value acquisition unit 21 outputs each data of the evaluation value to the brake operation determination unit 23.

  The threshold value determination unit 22 acquires the luminance value of the captured image and the shutter value and gain value data set by the preprocessing unit 13 from the output signal of the preprocessing unit 13 for each frame, and the brightness of the subject is determined. Threshold values A and B for determining whether or not the range is in a predetermined range and threshold value C for determining whether or not the brake lamp is lit are dynamically determined (step S12). ).

  Whether the brake operation determination unit 23 can detect the lighting of the brake lamp by comparing the current frame evaluation value (referred to as “current evaluation value” in FIG. 2) with the thresholds A and B. Is determined (step S13).

  In step S13, the brake operation determination unit 23 determines that the subject is too dark when the current frame evaluation value is less than the threshold value A, and the subject is bright when the current frame evaluation value is greater than the threshold value B. It is determined that it is too much, and the process is terminated without determining whether or not the brake operation is performed.

  On the other hand, in step S13, the brake operation determination unit 23 proceeds to step S14 when the current frame evaluation value is equal to or greater than the threshold value A and equal to or less than B, and determines the presence or absence of the brake operation.

  The brake operation determination unit 23 determines whether the absolute value of the inter-frame evaluation value difference between the current frame evaluation value and the previous frame evaluation value (referred to as “previous evaluation value” in FIG. 2) is greater than or equal to a threshold value C. Determination is made (step S14).

  In step S14, when it is determined that the absolute value of the inter-frame evaluation value difference is less than the threshold value C, the brake operation determination unit 23 determines that the brake operation is not performed and ends the process.

  On the other hand, in step S14, the brake operation determination unit 23 determines that the brake operation has been performed when it is determined that the absolute value of the inter-frame evaluation value difference is equal to or greater than the threshold value C, and the process proceeds to step S15.

  The brake operation determination unit 23 determines whether or not the current frame evaluation value is larger than the previous frame evaluation value (step S15).

  In step S15, when the brake operation determination unit 23 determines that the current frame evaluation value is greater than the previous frame evaluation value, the brake operation determination unit 23 outputs a brake lighting signal indicating that the brake lamp has been turned on from a light-off state ( Step S16).

  On the other hand, if the brake operation determination unit 23 does not determine in step S15 that the current frame evaluation value is greater than the previous frame evaluation value, the brake light-off signal indicating that the brake lamp has changed from the on state to the off state. Is output (step S17).

  As described above, according to the brake operation detection device 20 in the present embodiment, the brake operation detection device 20 is configured to determine the presence or absence of the brake operation based on the change amount of the color component included in the captured image captured by the imaging device 10. Internal wiring from the sensor to the imaging device 10 becomes unnecessary. Therefore, the brake operation detection device 20 according to the present embodiment can reduce the number of internal wires as compared with the conventional case.

  In addition, the brake operation detection device 20 according to the present embodiment is configured such that the evaluation value acquisition unit 21 acquires not only the R component, which is the main component of the brake lamp, but also the G component and B component intensity values. It can correspond to various brake lamps having different spectra.

  As described above, the brake operation detection device according to the present invention has an effect that the number of internal wirings can be reduced as compared with the prior art, and uses the output signal of the in-vehicle imaging device that images the outside of the vehicle. It is useful as a brake operation detection device that detects a driver's brake operation.

DESCRIPTION OF SYMBOLS 1 Brake operation detection system 10 Imaging device 11 Lens part 12 Image sensor 13 Preprocessing part 14 Exposure control part 15 Drive processing part 16 Signal processing part 20 Brake operation detection apparatus 21 Evaluation value acquisition part 22 Threshold value determination part 23 Brake operation determination Part

Claims (5)

Brake operation detection that detects the presence or absence of a driver's brake operation in a vehicle equipped with an imaging device that can image a subject outside the host vehicle at predetermined frame intervals and sense the lighting light of the brake lamp of the host vehicle A device,
It is determined that the brake operation is performed when an inter-frame change amount of the intensity of at least one color component among a plurality of color components included in a captured image captured by the imaging device exceeds a predetermined threshold value. A brake operation detection device comprising a brake operation determination unit that performs the operation. A threshold value determining unit for dynamically determining the threshold value;
The imaging apparatus includes an imaging device that images the subject, a gain correction unit that performs gain correction on an output signal of the imaging device, an exposure that determines a shutter value of the imaging device and a gain value of the gain correction unit. A control unit,
The threshold value determination unit dynamically determines the threshold value based on the shutter value, the gain value, and a luminance value of captured image data output by the gain correction unit. The brake operation detection device according to claim 1. The threshold value determination unit recognizes the brightness of the subject based on the shutter value, the gain value, and the luminance value of the data of the captured image output by the gain correction unit,
The brake operation determination unit stops detection of the brake operation when the threshold value determination unit recognizes that the brightness of the subject is outside a predetermined range. The brake operation detection apparatus of Claim 1 or Claim 2.   The threshold value determination unit is configured to determine whether or not the brake operation is performed in a direction in which the intensity of the at least one color component increases, and in the direction in which the intensity of the at least one color component decreases. The brake operation detection device according to any one of claims 1 to 3, wherein a second threshold value for determining presence or absence of a brake operation is determined.   In the image obtained by dividing the picked-up image picked up by the image pickup device into a plurality of blocks, the brake operation determination unit is configured such that an amount of change between frames of the intensity of the at least one color component among the plurality of blocks has the threshold value. The brake operation detection device according to any one of claims 1 to 4, wherein the brake operation is determined to be performed when there is an excess block.

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