WO2015068301A1 - Speed detection device, speed detection method, speed detection program, and recording medium - Google Patents

Abstract

　An imaging unit (210A) is controlled while a relative speed output unit (113A) performs control for alternately switching, via an illumination switching unit (112) at each predetermined time, illumination by a plurality of illumination units (120A₁, 120A₂) for illuminating a road surface at mutually different angles, and an image of the road surface is captured. Then, the relative speed output unit (113A) determines the illumination unit that corresponds to a captured image for calculating speed information of a moving body (MV) on the basis of the captured image from the imaging unit (210A) obtained via an acquisition unit (111A). The relative speed output unit (113A) then calculates relative sped information (VLI) of each time point on the basis of the captured image at the time of illumination by the determined illumination unit and outputs the calculated relative speed information (VLI). As a result, relative speed information can be calculated with good precision and outputted even when the state of the road surface changes moment by moment.

Description

Speed detection device, speed detection method, speed detection program, and recording medium

The present invention relates to a speed detection device, a speed detection method, a speed detection program, and a recording medium on which the speed detection program is recorded.

Conventionally, the speed of a moving body such as a vehicle is detected, and the detected speed is presented to the user or used for driving control for safe driving. Various techniques for detecting the speed of such a moving body have been proposed. Among them, an image of the vicinity of the host vehicle including the road surface is imaged by an imaging unit mounted on the vehicle, and the vehicle is detected based on the imaging result. There is a technique for detecting the speed (see Patent Document 1: hereinafter referred to as “conventional example”).

In the technique of this conventional example, when at least a part of the image area of the road marking exists in the captured image, the host vehicle is based on the dimension of the road marking in the captured image and the dimension of the road marking on the road. The vehicle speed is detected. In the conventional technique, the vehicle body speed is detected only when the road marking is present in the image, and only the running / stop determination is performed when the road marking is not present in the image.

JP 2009-205642 A

In the conventional technique described above, the vehicle body speed is not detected when there is no road marking in the captured image. For this reason, even if the vehicle speed changes while the road marking is not present in the captured image, the vehicle speed detected at the time when the road marking was last present in the captured image is used as it is. It will be estimated as speed. For this reason, it is difficult to accurately detect the vehicle speed at each time point.

Therefore, it is conceivable that the road surface is periodically imaged while illuminating the imaging target range, and the vehicle body speed is detected based on the time change of the imaging result. In order to detect the vehicle speed with high accuracy using such a method, it is necessary to consider that the road surface condition around the vehicle changes every moment. This is because it is considered that the illumination suitable for imaging differs according to the road surface state. However, at present, proposals have been made for a technique for detecting the vehicle speed in consideration of what kind of lighting is preferable in response to the road surface condition around the vehicle that is changing every moment. Not.

For this reason, when the road surface condition around the vehicle changes every moment, there is a demand for a technology that can continuously and accurately detect the vehicle body speed based on a road surface image obtained by appropriate illumination corresponding to the road surface condition. Responding to such a request is cited as one of the problems to be solved by the present invention.

The present invention has been made in view of the above, and it is an object of the present invention to provide a speed detection device and a speed detection method that can accurately detect speed information of a moving object even if a road surface state changes every moment. To do.

The invention according to claim 1 is an acquisition unit that acquires a captured image obtained by an imaging unit mounted on a moving body capturing an imaging target; a plurality of illumination units that illuminate the imaging target at mutually different angles An illumination switching unit that sequentially switches one illumination unit that illuminates the imaging target at a predetermined time interval; and a relative speed between the imaging target and the imaging unit based on the captured image acquired by the acquisition unit. And a relative speed information output unit that outputs information on the speed detection device.

The invention according to claim 10 is a speed detection method used by a speed detection device including a plurality of illumination units that illuminate an imaging target at mutually different angles, and the illumination unit that illuminates the imaging target includes: An illumination switching step that sequentially switches at a predetermined time interval; an acquisition step in which an imaging unit mounted on a moving body acquires a captured image obtained by imaging the imaging target; and a captured image acquired in the acquisition step And a relative speed information output step for outputting information on the relative speed between the imaging target and the imaging unit.

The invention described in claim 11 is a speed detection program that causes a computer included in the speed detection device to execute the speed detection method described in claim 10.

The invention described in claim 12 is a recording medium in which the speed detection program according to claim 11 is recorded so as to be readable by a computer included in the speed detection device.

It is a figure which shows the structure of the speed detection apparatus which concerns on 1st Embodiment of this invention. It is a figure for demonstrating the structure of the two illumination parts of FIG. It is a figure for demonstrating the reflected light when the illumination light inject | emitted from the illumination part of FIG. 2 is reflected by the diffuse reflection path surface. It is a figure for demonstrating the reflected light when the illumination light inject | emitted from the illumination part of FIG. 2 is reflected by the mirror-reflection path surface. 2 is a timing chart for explaining timings of signal issuance of a relative speed output unit in FIG. 1 and output of captured image data from the imaging unit. It is a figure for demonstrating the detection process of the relative speed information by the relative speed output part of FIG. It is a figure which shows the structure of the speed detection apparatus which concerns on 2nd Embodiment of this invention. It is a figure for demonstrating the structure of the two illumination parts of FIG. It is a figure for demonstrating the reflected light when the illumination light inject | emitted from the illumination part of FIG. 8 is reflected by the diffuse reflection path surface. It is a figure for demonstrating the reflected light when the illumination light inject | emitted from the illumination part of FIG. 8 is reflected by the mirror-reflection path surface. It is a timing chart for demonstrating the timing of the signal issue of the relative speed output part of FIG. 7, and the output of the captured image data from an imaging part. It is a figure for demonstrating the detection process of the relative speed information by the relative speed output part of FIG.

100A, 100B ... Speed detection device 111A, 111B ... Acquisition unit 112 ... Illumination switching unit 113A, 113B ... Relative speed output unit (relative speed information output unit)
120A ₁ , 120B ₁ ... 1st illumination part 120A ₂ , 120B ₂ ... 2nd illumination part 210A, 210B ... Imaging part MV ... Mobile

Hereinafter, embodiments of the present invention will be described with reference to FIGS. In the following description and drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

[First Embodiment]
First, a first embodiment of the present invention will be described with reference to FIGS.

<Configuration>
FIG. 1 is a block diagram showing the configuration of the speed detection device 100A according to the first embodiment. As shown in FIG. 1, the speed detection device 100 </ b> A is connected to the imaging unit 210 </ b> A and the control device 220. The speed detection device 100A, the imaging unit 210A, and the control device 220 are mounted on the moving body MV.

The imaging unit 210A is mounted at a fixed position of the moving body MV, and images a road surface immediately below the fixed position. When the imaging unit 210A receives an imaging command IMC sent from the speed detection device 100A, the imaging unit 210A performs imaging. Then, the imaging unit 210A sends the captured image data IMD to the speed detection device 100A.

It is assumed that the optical magnification m at the time of imaging by the imaging unit 210A is known.

The control device 220 acquires the relative speed information VLI output from the speed detection device 100A. Then, the control device 220 uses the acquired relative speed information VLI for traveling control of the moving body MV and the like.

In addition, when the moving body MV is a vehicle, the control device 220 corresponds to an ECU (Electronic Control Unit). Such an ECU acquires sensor detection information detected by various sensors such as an acceleration sensor and an angular velocity sensor, in addition to the relative speed information VLI. The ECU controls traveling of the moving body MV and provides traveling information to the user.

The speed detection device 100A includes a control processing unit 110A as shown in FIG. Also, the speed detecting device 100A includes a first illumination portion 120A _1, the second illumination section 120A _2.

The control processing unit 110A controls switching between emission of illumination light by the first illumination unit 120A ₁ and emission of illumination light by the second illumination unit 120A ₂ and controls imaging of the imaging unit 210A. In addition, the control processing unit 110A generates the relative speed information VLI between the road surface and the moving body MV based on the captured image data IMD sent from the imaging unit 210A, and the generated relative speed information VLI to the control device 220. Output. The control processing unit 110A having such a function includes an acquisition unit 111A, an illumination switching unit 112, and a relative speed output unit 113A.

The acquisition unit 111A receives the captured image data IMD sent from the imaging unit 210A. Then, the acquisition unit 111A sends the captured image data IMD to the relative speed output unit 113A.

The illumination switching unit 112 receives the illumination switching control LSC sent from the relative speed output unit 113A. The illumination switching control LSC includes an illumination switching control LSC ₁ that designates illumination by the first illumination unit 120A ₁ and an illumination switching control LSC ₂ that designates illumination by the second illumination unit 120A ₂ .

Upon receiving the illumination switching control LSC ₁ , the illumination switching unit 112 sets the illumination designation LC ₁ to “ON” and sends it to the first illumination unit 120A _1, and sets the illumination designation LC ₂ to “OFF” and the second illumination unit 120A. Send to ₂ . Upon receiving the illumination switching control LSC ₂ , the illumination switching unit 112 sets the illumination designation LC ₁ to “OFF” and sends it to the first illumination unit 120A _1, and sets the illumination designation LC ₂ to “ON” and the second illumination. send to part 120A _2.

The relative speed output unit 113A generates the illumination switching control LSC for alternately switching the illumination unit that emits illumination light to the road surface every time the time TPA elapses, and illuminates the generated illumination switching control LSC. The data is sent to the switching unit 112. That is, the relative speed output unit 113A generates the illumination switching control LSC ₂ when the time TPA has elapsed after sending the illumination switching control LSC ₁ to the illumination switching unit 112, and the generated illumination switching control LSC ₂ is used as the illumination switching unit. 112. Thereafter, when the time TPA elapses, the relative speed output unit 113A generates the illumination switching control LSC ₁ and sends the generated illumination switching control LSC to the illumination switching unit 112.

Note that the “time TPA” is such that a common road surface area is included in the two images captured by the imaging unit 210A with a time (2 · TPA) even when the moving body MV is traveling at high speed. From this point of view, it is predetermined based on experiments, simulations, and the like.

The relative speed output unit 113A sends the imaging command IMC to the imaging unit 210A after issuing the new illumination switching control LSC ₁ and after issuing the new illumination switching control LSC ₂ . As a result, the imaging unit 210A captures the road surface every time the time TPA elapses, and sends the captured image data IMD to the acquisition unit 111A.

In the first embodiment, the relative speed output unit 113A is configured to temporarily “ON” the signal of the imaging command IMC when instructing imaging.

Also, the relative speed output unit 113A receives the captured image data IMD sent from the imaging unit 210A via the acquisition unit 111A. Then, the relative speed output unit 113A calculates the moving body speed based on the captured image data IMD. The moving body speed thus calculated is output to the control device 220 as relative speed information VLI.

The processing executed by the relative speed output unit 113A will be described later.

The first illumination unit 120A ₁ receives the illumination designation LC ₁ sent from the illumination switching unit 112. Then, the first illumination unit 120A ₁ emits illumination light over a period in which the illumination designation LC ₁ is “ON”. Note that the first illumination unit 120A ₁ does not emit illumination light during a period in which the illumination designation LC ₁ is “OFF”.

The second illumination unit 120A ₂ receives the illumination designation LC ₂ sent from the illumination switching unit 112. The second illumination unit 120A ₂ the illumination designation LC ₂ is a period of "ON", to emit the illumination light. Note that the second illumination unit 120A ₂ does not emit illumination light during the period when the illumination designation LC ₂ is “OFF”.

Here, the configuration of the first illumination unit 120A ₁ and the second illumination unit 120A ₂ will be described in more detail with reference to FIG. 2 while paying attention to the relationship with the imaging unit 210A. As shown in FIG. 2, the imaging unit 210A includes an imaging device PRD, a lens LZ _1, a half mirror HMR, a lens LZ _2. As described above, the imaging unit 210A captures an area on the road surface RDP directly below.

In the imaging unit 210A, the imaging optical system is formed by the lens LZ ₁ and the lens LZ ₂ .

The first illumination unit 120A ₁ includes a light source device PED ₁ , a lens LZ ₃ , a half mirror HMR, and a lens LZ ₂ . That is, the first illumination unit 120A ₁ shares the half mirror HMR and the lens LZ ₂ with the imaging unit 210A. The first illumination unit 120A ₁ emits illumination light for realizing coaxial epi-illumination for the imaging unit 210A over a period when the illumination designation LC ₁ is “ON”, and the imaging target region of the road surface RDP by the imaging unit 210A Illuminate.

The first in the lighting unit 120A _1, so that the collimating optical system is formed by the lens LZ ₃ and the lens LZ _2.

In the first illumination unit 120A ₁ , the light source device PED ₁ emits light having an optical axis in the horizontal direction toward the half mirror HMR over a period in which the illumination designation LC ₁ is “ON”. A part of the light emitted from the light source device PED ₁ is reflected vertically downward by the half mirror HMR, and then passes through the lens LZ _2, thereby being coaxial with the optical axis of the imaging optical system of the imaging unit 210A. It is collimated to become Thus collimated light is emitted as illumination light from the first illuminating portion 120A _1, to illuminate the image capturing target area of the road surface RDP by the imaging unit 210A.

Second illumination section 120A ₂ includes a light source device PED _2, a lens LZ _4, a lens LZ _5. The second illumination unit 120A ₂ emits illumination light for realizing oblique illumination for the imaging unit 210A over a period in which the illumination designation LC ₂ is “ON”, and sets an imaging target region of the road surface RDP by the imaging unit 210A. Illuminate.

In the second illumination unit 120A ₂ , collimation is formed by the collimating optical system formed by the lens LZ ₄ and the lens LZ ₅ .

In the second illumination unit 120A ₂ , the light source device PED ₂ emits light having an optical axis that is oblique to the optical axis of the imaging unit 210A over a period in which the illumination designation LC ₂ is “ON”. The light emitted from the light source device PED ₂ is collimated by the lens LZ ₄ and the lens LZ ₅ . Thus collimated light is emitted as illumination light from the second illumination section 120A _2, illuminates an imaging target area of the road surface RDP by the imaging unit 210A.

"The first reflected light upon illumination by the illumination unit 120A ₁ and the second illumination section 120A _2"
Here it will be described the reflected light in the road RDP during illumination by the first respective lighting unit 120A ₁ and the second illumination section 120A _2.

(When the road surface is a diffuse reflection surface)
FIG. 3 (A), when the road surface RDP is diffuse reflection surface, an example of a state of reflection on the road surface RDP when illuminated by the first illuminating portion 120A ₁ is indicated by a bold arrow. In FIG. 3A, the intensity of reflected light is indicated by the length of the thick arrow (the same applies to FIGS. 3B, 4A, and 4B described later). ).

As shown in FIG. 3 (A), a road surface RDP is dry, when the road surface RDP is a diffuse reflecting surface, when illuminated by the first illumination unit 120A _1, the illumination light in the road RDP Reflected in each direction. For this reason, a part of the reflected light is incident on the imaging unit 210A. Then, the image of the imaging target area of the road surface RDP that the incident light bears is imaged by the imaging optical system of the imaging unit 210A formed by the lens LZ ₁ and the lens LZ ₂ (see FIG. 2). The image result is imaged by the imaging device PRD (see FIG. 2) of the imaging unit 210A described above.

FIG 3 (B), when the same way road RDP in the case shown in FIG. 3 (A) is in the diffuse reflection surface, the state of reflection on the road surface RDP in when illuminated by the second illumination section 120A ₂ An example is indicated by a thick arrow. As shown in FIG. 3 (B), when the road surface RDP is diffuse reflecting surface, when illuminated by the second illumination section 120A _2, as in the case of FIG. 3 described above (A), the illumination light Is reflected in each direction on the road surface RDP. For this reason, a part of the reflected light is incident on the imaging unit 210A. Similarly to the case of FIG. 3A, the image of the imaging target area of the road surface RDP that the incident light bears is imaged by the imaging optical system of the imaging unit 210A, and the imaging result is the imaging unit 210A described above. The imaging device PRD captures an image.

As described above, when the road surface RDP is a diffuse reflection surface, the imaging target region on the road surface RDP is illuminated by the first illumination unit 120A ₁ or the second illumination unit 120A _2. Can be imaged. However, even with a diffuse reflection surface, the sharpness of the captured image of the unevenness varies depending on the unevenness of the road surface RDP. For example, low degree of unevenness of the road surface RDP, in the case of high concrete surface flatness, rather than illumination of the first illuminating portion 120A ₁ found the following illumination by the second illumination section 120A _2, unevenness of the road surface is highlighted Thus, a captured image with high sharpness is obtained. For this reason, in-image characteristics for matching in the case where the illumination by the second illumination unit 120A ₂ detects the moving body speed with respect to the road surface RDP using the so-called displacement amount search method than the illumination by the first illumination unit 120A _1. Many areas can be extracted.

Note that when the road surface RDP is higher asphalt surface of degree of unevenness, even illumination of the first illuminating portion 120A _1, even illumination with the second illuminating portion 120A _2, the same sharpness The unevenness is imaged.

(When the road surface is a specular reflection surface)
Figure 4 (A) is a road surface RDP is flooded state, when the road surface RDP is a specular surface, an example of a state of reflection on the road surface RDP in when illuminated by the first illumination portion 120A ₁ It is indicated by a thick arrow. As shown in FIG. 4 (A), when the road surface RDP is specular reflective surface, when illuminated by the first illumination unit 120A _1, the illumination light in the road RDP, opposite to the incident direction of the road surface RDP Reflected in the direction. For this reason, most of the reflected light is incident on the imaging unit 210A. Then, the image of the imaging target area of the road surface RDP that is carried by the incident light is imaged by the imaging optical system of the imaging unit 210A, and the imaging result is captured by the imaging device PRD of the imaging unit 210A.

The FIG. 4 (B), the similar to the case of FIG. 4 (A), when the road surface RDP is a specular surface, state of reflection on the road surface RDP in when illuminated by the second illumination section 120A ₂ The example is shown by a thick arrow. As shown in FIG. 4B, when the road surface RDP is a specular reflection surface, when the second illumination unit 120A ₂ illuminates, the light emitted from the second illumination unit 120A ₂ passes through the road surface RDP. It is specularly reflected and most of it does not enter the imaging unit 210A. Therefore, in the case of illumination by the second illumination section 120A ₂ are that the extraction of the image feature area for matching in the case of detecting the moving body speed relative to the road surface RDP by using a so-called displacement search method becomes difficult Conceivable.

Even when the road surface RDP is in a snowy state, the road surface RDP becomes a diffuse reflection surface. In this case, the intensity of the reflected light on the road surface RDP is higher than when the road surface RDP is in a dry state.

In addition, when the road surface RDP is in a frozen state, the reflected light on the road surface RDP is in an intermediate state between the above-described FIG. 3A and FIG. 4A.

<Operation>
Next, the operation of the speed detection device 100A configured as described above will be described mainly focusing on the speed detection process executed by the relative speed output unit 113A.

In the following description, the description “captured image data IMD _{j, k} ” is based on the first illumination unit 120A ₁ (when j = 1) and the second illumination unit 120A ₂ (when j = 2). It means the kth captured image data at the time of illumination. In addition, initially, the illumination switching unit 112 is assumed to set both the illumination designation LC ₁ and the illumination designation LC ₂ to “OFF”.

When starting the speed detecting process, as shown in FIG. 5, the relative velocity output unit 113A generates the illumination switch control LSC _1, and sends the generated illumination switch controlling LSC ₁ to the lighting switch unit 112. Upon receiving this illumination switching control LSC ₁ , the illumination switching unit 112 sets the illumination designation LC ₁ to “ON” and sends it to the first illumination unit 120 </ _b > A _1, and sets the illumination designation LC ₂ to “OFF” and the second illumination unit. send to 120A _2. As a result, the illumination light only from the first illuminating portion 120A ₁ is injected, the road surface is illuminated by illumination light the injection.

Subsequently, the relative speed output unit 113A sends an imaging command IMC to the imaging unit 210A. As a result, the imaging of the road surface is performed by the imaging unit 210A, and the imaging result is sent to the speed detection device 100A as the captured image data IMD _1,1 .

The relative speed output unit 113A receives the captured image data IMD _1,1 via the acquisition unit 111A. Then, the relative speed output unit 113A extracts the characteristic of the feature region and the position in the image in the captured image corresponding to the captured image data IMD _1,1 .

In addition, the relative speed output unit 113A obtains the sharpness CT _{1,1 of the} captured image. In the first embodiment, the relative speed output unit 113A obtains the standard deviation of the brightness of the pixels of the captured image as the sharpness of the captured image. The sharpness obtained in this way increases as the value increases.

Next, when the elapsed time from the issuance processing of the illumination switching control LSC ₁ corresponding to the captured image data IMD _1,1 reaches the time TPA, the relative speed output unit 113A generates the illumination switching control LSC ₂ and is generated. The illumination switching control LSC ₂ is sent to the illumination switching unit 112. Upon receiving this illumination switching control LSC ₂ , the illumination switching unit 112 sets the illumination designation LC ₁ to “OFF” and sends it to the first illumination unit 120 </ _b > A _1, and sets the illumination designation LC ₂ to “ON” and the second illumination unit. send to 120A _2. As a result, the illumination light only from the second illumination section 120A ₂ is emitted, the road surface is illuminated by illumination light the injection.

Subsequently, the relative speed output unit 113A sends an imaging command IMC to the imaging unit 210A. As a result, the road surface is imaged by the imaging unit 210A, and the imaging result is sent to the speed detection device 100A as captured image data IMD _2,1 .

The relative speed output unit 113A receives the captured image data IMD _2,1 via the acquisition unit 111A. Then, the relative speed output unit 113A extracts the characteristics of the feature region and the position in the image in the captured image corresponding to the captured image data IMD _2,1 , and obtains the sharpness CT _{2,1 of the} captured image.

Next, when the elapsed time from the issuance processing of the illumination switching control LSC ₂ corresponding to the captured image data IMD _2,1 reaches the time TPA, the relative speed output unit 113A generates the illumination switching control LSC ₁ and the generated illumination The switching control LSC ₁ is sent to the illumination switching unit 112. As a result, again, the illuminating light only from the first illuminating portion 120A ₁ is injected, the road surface is illuminated by illumination light the injection.

Subsequently, the relative speed output unit 113A sends an imaging command IMC to the imaging unit 210A. As a result, the imaging of the road surface is performed by the imaging unit 210A, and the imaging result is sent to the speed detection device 100A as the captured image data IMD _1,2 .

The relative speed output unit 113A receives the captured image data IMD _1,2 via the acquisition unit 111A. Then, the relative velocity output unit 113A extracts the characteristics and image position of the characteristic region in the captured image corresponding to the captured image data IMD _{1, 2,} obtaining the sharpness CT _{1, 2} of the captured image.

Next, the relative speed output unit 113A extracts the feature region extracted from the captured image corresponding to the captured image data IMD _1,2 and the captured image data IMD _1,1 (that is, IMD _{1, k} when k = 2). _-1 ), a common feature region is specified with the feature region extracted from the captured image corresponding to ( ₁ ). Then, the relative speed output unit 113A calculates the number NC ₁ of the specified common specific areas. Subsequently, the relative speed output unit 113A calculates the average of the above-described sharpness CT _1,1 and sharpness CT _1,2 as the sharpness CT ₁ of the captured image at the time of illumination by the first illumination unit 120A ₁ .

Next, when the elapsed time from the issuance processing of the illumination switching control LSC ₁ corresponding to the captured image data IMD _1,2 reaches the time TPA, the relative speed output unit 113A generates the illumination switching control LSC ₂ and is generated. The illumination switching control LSC ₂ is sent to the illumination switching unit 112. Upon receiving this illumination switching control LSC ₂ , the illumination switching unit 112 sets the illumination designation LC ₁ to “OFF” and sends it to the first illumination unit 120 </ _b > A _1, and sets the illumination designation LC ₂ to “ON” and the second illumination unit. send to 120A _2. As a result, again, the illuminating light only from the second illumination section 120A ₂ is emitted, the road surface is illuminated by illumination light the injection.

Subsequently, the relative speed output unit 113A sends an imaging command IMC to the imaging unit 210A. As a result, the road surface is imaged by the imaging unit 210A, and the imaging result is sent as the captured image data IMD _2,2 to the speed detection device 100A.

The relative speed output unit 113A receives the captured image data IMD _2,2 via the acquisition unit 111A. Then, the relative speed output unit 113A extracts the characteristics of the feature region and the position in the image in the corresponding captured image of the captured image data IMD _2,2 , and obtains the sharpness CT _{2,2 of the} captured image.

Next, the relative speed output unit 113A outputs the feature region extracted from the captured image corresponding to the captured image data IMD _2,2 and the captured image data IMD _2,1 (that is, IMD _{2, k} when k = 2). _-1 ) A common feature area with the feature area extracted from the captured image corresponding to ₁ ) is specified. Then, the relative speed output unit 113A determines the number NC ₂ of the specified common specific areas. Subsequently, the relative velocity output unit 113A, the average of the sharpness CT _2,1 and sharpness CT _{2, 2} described above is calculated as the sharpness CT ₂ of the captured image during illumination by the second illumination section 120A _2.

Next, the relative speed output unit 113A compares the number NC ₁ and the number NC ₂ described above. When the number NC ₁ and the number NC ₂ are different, the relative speed output unit 113A uses the two latest captured images at the time of illumination by the lighting unit corresponding to the larger number as the speed calculation image. To do.

On the other hand, when the number NC ₁ and the number NC ₂ are equal, the relative speed output unit 113A compares the sharpness CT ₁ and the sharpness CT ₂ described above. Then, the relative speed output unit 113A sets the two latest captured images at the time of illumination by the illumination unit corresponding to the higher sharpness as the speed calculation images.

When the speed calculation image is thus determined, the relative speed output unit 113A calculates the intra-image movement amount of the common feature region between the two determined captured images as the pixel movement amount ΔD. When there are a plurality of common feature areas, the relative speed output unit 113A calculates the individual pixel movement amount for each of the feature areas, and then sets the average of the calculated individual pixel movement amounts as the pixel movement amount ΔD. calculate.

Subsequently, the relative speed output unit 113A calculates the moving body speed V of the moving body MV by the following equation (1).
V = ΔD / (m · TPA) (1)
Then, the relative speed output unit 113A outputs the calculated moving body speed V to the control device 220 as the relative speed information VLI.

Thereafter, each time TPA elapses from the previous issuance of the illumination switching control LSC, the relative speed output unit 113A moves from the issuance of the illumination switching control LSC ₁ for acquiring the above-described captured image data IMD _1,2. The process up to the calculation of the body speed V is repeated. As a result, the moving body speed V is calculated every time (2 · TPA), and is output to the control device 220 as the relative speed information VLI.

FIG. 6 shows an example of the moving body speed calculation process by the relative speed output unit 113A. In FIG. 6, the common feature region is 2 region of the A area and the B area, the individual pixel movement amount of each of these 2 regions [Delta] D _A, an example of calculating a moving body velocity V on the basis of the [Delta] D _B are shown ing.

As described above, in the first embodiment, the illumination by the first illuminating portion 120A ₁ for illuminating the road surface at different angles from each other, and illumination by the second illumination section 120A _2, the relative velocity output unit 113A is the illumination switch The imaging unit 210A is controlled to perform the imaging of the road surface while performing the control to alternately switch every time TPA via the unit 112. Subsequently, the relative speed output unit 113A illuminates corresponding to the captured image for calculating the relative speed information of the moving body MV and the road surface based on the image captured by the image capturing unit 210A obtained via the acquisition unit 111A. To decide. Then, the relative speed output unit 113 </ b> A calculates relative speed information at each time point based on the determined captured image at the time of illumination by the lighting unit, and outputs the calculated relative speed information to the control device 220.

Therefore, according to the first embodiment, even if the road surface state changes every moment, the relative speed information between the moving body MV and the road surface can be detected with high accuracy.

In the first embodiment, the first illumination unit 120A ₁ performs coaxial epi-illumination, and the second illumination unit 120A ₂ performs oblique illumination. For this reason, a road surface image can be obtained on any of the diffuse reflection road surface and the specular reflection road surface, and an image with appropriate sharpness can be acquired corresponding to the degree of unevenness on the diffusion road surface. The relative speed information between the MV and the road surface can be detected with high accuracy.

In the first embodiment, the number of feature region common between the two captured images obtained during illumination of temporally successive with the same lighting unit, in the case of illumination by the first illuminating portion 120A ₁ and , compared with the case of the illumination by the second illumination section 120A _2, based on the captured image at the time of lighting the number of common features area by a greater illumination unit, the relative speed information of the moving body MV and the road surface To detect. Further, when the number of common feature areas is the same, the speed information of the moving body is detected based on the captured image at the time of illumination by the illuminating unit having a higher sharpness of the captured image. For this reason, the relative speed information between the moving body MV and the road surface can be detected reasonably accurately.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference mainly to FIGS.

<Configuration>
FIG. 7 is a block diagram showing the configuration of the speed detection device 100B according to the second embodiment. As shown in FIG. 7, the speed detection device 100 </ b> B is connected to the imaging unit 210 </ b> B and the control device 220. The speed detection device 100B, the imaging unit 210B, and the control device 220 are mounted on the moving body MV.

The above imaging unit 210B includes a first imaging unit 210B _{1, 2} and the second imaging unit 210B.

First imaging unit 210B ₁ of the above are mounted on a fixed first position of the mobile MV, images the road surface below the said first position. When the first imaging unit 210B ₁ receives the imaging command IMC ₁ sent from the speed detection device 100B, the first imaging unit 210B ₁ performs imaging. Then, the first imaging unit 210B ₁ sends the captured image data IMD ₁ to the speed detection device 100B.

Second imaging unit 210B ₂ above, is mounted on fixed second position of the mobile MV, images the road surface below the said second position. When receiving the imaging command IMC ₂ sent from the speed detection device 100B, the second imaging unit 210B ₂ performs imaging. Then, the second imaging unit 210B ₂ sends the captured image data IMD ₂ to the speed detection device 100B.

In the following description, it is assumed that the optical magnification at the time of imaging by the first imaging unit 210B ₁ and the second imaging unit 210B ₂ is both “m” and known.

The speed detection device 100B includes a control processing unit 110B as shown in FIG. The speed detection device 100B includes a first illumination unit 120B ₁ and a second illumination unit 120B ₂ .

Said control processing unit 110B includes an injection of the illumination light by the first illumination unit 120B _1, and controls the switching between the exit of the illumination light by the second illumination unit 120B _2, the imaging and the by the first imaging unit 210B ₁ 2 controls the imaging by the imaging unit 210B _2. In addition, the control processing unit 110B generates relative speed information VLI between the road surface and the moving object MV based on the captured image data IMD ₁ and IMD ₂ sent from the first imaging unit 210B ₁ and the second imaging unit 210B _2. Then, the generated relative speed information VLI is output to the control device 220. The control processing unit 110B having such a function includes an acquisition unit 111B, an illumination switching unit 112, and a relative speed output unit 113B.

The acquisition unit 111B receives the captured image data IMD ₁ sent from the first imaging unit 210B ₁ and the captured image data IMD ₂ sent from the second imaging unit 210B ₂ . Then, the acquisition unit 111B sends the captured image data IMD ₁ and IMD ₂ to the relative speed output unit 113B.

The illumination switching unit 112 performs the same operation as in the first embodiment described above in response to the illumination switching control LSC sent from the relative speed output unit 113B.

The relative speed output unit 113B generates an illumination switching control LSC for alternately switching an illumination unit that emits illumination light to the road surface every time TPB elapses, and illuminates the generated illumination switching control LSC. The data is sent to the switching unit 112. That is, when the time TPB has elapsed after sending the illumination switching control LSC ₁ to the illumination switching unit 112, the relative speed output unit 113B generates the illumination switching control LSC ₂ and uses the generated illumination switching control LSC ₂ as the illumination switching unit. 112. Thereafter, the time when the TPB has elapsed, the relative velocity output unit 113B generates the illumination switch control LSC _1, and sends the generated illumination switch controlling LSC ₁ to the lighting switch unit 112.

Note that “time TPB” refers to two images captured by the first imaging unit 210B ₁ or the second imaging unit 210B ₂ with a time (TPB / 2) apart even when the moving body MV is traveling at high speed. From the viewpoint of including a common road surface area, it is determined in advance based on experiments, simulations, and the like.

The relative speed output unit 113B sends the imaging command IMC ₁ to the first imaging unit 210B ₁ after issuing a new illumination switching control LSC ₁ . Thereafter, when the time (TPB / 2) elapses, the imaging command IMC ₁ is sent again to the first imaging unit 210B ₁ . As a result, the first imaging unit 210B ₁ is separated by a time (TPB / 2), captures an image of the road twice each time imaging, and sends the captured image data IMD ₁ to acquiring unit 111B.

In addition, the relative speed output unit 113B sends the imaging command IMC ₂ to the second imaging unit 210B ₂ after the new illumination switching control LSC ₂ is issued. Thereafter, when the time (TPB / 2) elapses, the imaging command IMC ₂ is sent again to the second imaging unit 210B ₂ . As a result, the second imaging unit 210B ₂ is separated by a time (TPB / 2), captures an image of the road twice each time imaging, and sends the captured image data IMD ₂ to acquiring unit 111B.

The relative speed output unit 113B receives the captured image data IMD ₁ and IMD ₂ sent from the imaging unit 210B via the acquisition unit 111B. Then, the relative speed output unit 113B calculates the moving body speed based on the captured image data IMD ₁ and IMD ₂ . The moving body speed thus calculated is output to the control device 220 as relative speed information VLI.

The processing executed by the relative speed output unit 113B will be described later.

The first illumination unit 120B ₁ receives the illumination designation LC ₁ sent from the illumination switching unit 112. Then, the first illumination unit 120B ₁ emits illumination light over a period in which the illumination designation LC ₁ is “ON”. Note that the first illumination unit 120B ₁ does not emit illumination light during a period in which the illumination designation LC ₁ is “OFF”.

The second illumination unit 120B ₂ receives the illumination designation LC ₂ sent from the illumination switching unit 112. Then, the second illumination unit 120B ₂ emits illumination light over a period in which the illumination designation LC ₂ is “ON”. The second illumination unit 120B ₂ does not emit illumination light during the period when the illumination designation LC ₂ is “OFF”.

Here, the configuration of the first illumination unit 120B ₁ will be described in more detail with reference to FIG. 8A while paying attention to the relationship with the first imaging unit 210B ₁ .

FIG. 8A shows the configuration of the first illumination unit 120B ₁ along with the configuration of the first imaging unit 210B ₁ . As shown in FIG. 8 (A), the first imaging unit 210B ₁ includes an imaging device PRD _1, a lens LZ _11, and a lens LZ _12. Incidentally, so as the first imaging unit 210B _1, the imaging optical system in the lens LZ ₁₁ and the lens LZ ₁₂ is formed.

First illumination unit 120B ₁ has a light source device PED _1, a lens LZ _13, includes a polarizing filter (the polarizer) PL _1, a lens LZ _14. The first illumination unit 120B ₁ emits illumination light for realizing oblique illumination for imaging by the first imaging unit 210B ₁ over a period in which the illumination designation LC ₁ is “ON”, and the first imaging unit 210B ₁ Illuminates the imaging target area of the road surface RDP.

The first in the lighting unit 120B _1, so that the collimating optical system is formed by the lens LZ ₁₃ and the lens LZ _14.

In the first illumination unit 120B ₁ , the light source device PED ₁ emits light toward the lens LZ ₁₃ over a period in which the illumination designation LC ₁ is “ON”. The light emitted from the light source device PED ₁ and passing through the lens LZ ₁₃ is selected by the polarization filter PL _{1 after} the linear component of the polarization direction shown in FIG. It is collimated by passing through the lens LZ _14. Thus collimated light is emitted as illumination light from the first illumination unit 120B _1, to illuminate the image capturing target area of the road surface RDP by the first imaging unit 210B _1.

Next, the configuration of the second illumination unit 120B ₂ will be described in more detail with reference to FIG. 8B while paying attention to the relationship with the second imaging unit 210B ₂ .

FIG. 8B shows the configuration of the second illumination unit 120B ₂ along with the configuration of the second imaging unit 210B ₂ . As shown in FIG. 8B, the second imaging unit 210B ₂ includes an imaging device PRD ₂ , a lens LZ _21, and a lens LZ ₂₂ . Incidentally, so that the second imaging unit 210B _2, the image forming optical system in the lens LZ ₂₁ and the lens LZ ₂₂ is formed.

The second illumination unit 120B ₂ includes a light source device PED ₂ , a lens LZ ₂₃ , a polarization filter PL _2, and a lens LZ ₂₄ . The second illumination unit 120B ₂ emits illumination light for realizing oblique illumination for imaging by the second imaging unit 210B ₂ over a period when the illumination designation LC ₂ is “ON”, and the second imaging unit 210B _2. Illuminates the imaging target area of the road surface RDP.

In the second illumination unit 120B _2, so that the collimating optical system is formed by the lens LZ ₂₃ and the lens LZ _24.

In the second illumination unit 120B ₂ , the light source device PED ₂ emits light toward the lens LZ ₂₃ over a period in which the illumination designation LC ₂ is “ON”. The light emitted from the light source device PED ₂ and passing through the lens LZ ₂₃ is selected by the polarization filter PL _{2 after} the linear component of the polarization direction shown in FIG. It is collimated by passing through the lens LZ _24. Thus collimated light is emitted as illumination light from the second illumination unit 120B _2, illuminates an imaging target area of the road surface RDP by the second imaging unit 210B _2.

"The first reflected light upon illumination by the illumination unit 120B ₁ and the second illumination unit 120B _2"
Here, the reflected light on the road surface RDP during illumination by each of the first illumination unit 120B ₁ and the second illumination unit 120B ₂ will be described.

(When the road surface is a diffuse reflection surface)
The FIG. 9 (A), the if the road RDP is diffuse reflection surface, an example of a state of reflection on the road surface RDP is indicated by a thick arrow in when illuminated by the first illumination unit 120B _1. In FIG. 9A, the intensity of reflected light is indicated by the length of the thick arrow (the same applies to FIGS. 9B, 10A, and 10B described later). ).

As shown in FIG. 9 (A), a road surface RDP is dry, when the road surface RDP is a diffuse reflecting surface, when illuminated by the first illumination unit 120B _1, the illumination light in the road RDP Reflected in each direction. Therefore, part of the reflected light is incident on the first imaging unit 210B _1. Then, the imaging optical system of the first imaging unit 210B _{1 in which} the image of the imaging target region of the road surface RDP carried by the incident light is formed by the lens LZ ₁₁ and the lens LZ ₁₂ described above (see FIG. 8A). The imaging result is imaged by the imaging device PRD ₁ (see FIG. 8A) of the first imaging unit 210B ₁ described above.

FIG. 9B shows the state of reflection on the road surface RDP when illuminated by the second illumination unit 120B ₂ when the road surface RDP is a diffuse reflection surface as in FIG. 9A. An example is indicated by a thick arrow. As shown in FIG. 9B, when the road surface RDP is a diffuse reflection surface, the illumination light is illuminated by the second illumination unit 120B ₂ as in the case of FIG. 9A described above. Is reflected in each direction on the road surface RDP. Therefore, part of the reflected light is incident on the second imaging unit 210B _2. Then, the imaging optical system of the second imaging unit 210B _{2 in which} the image of the imaging target region of the road surface RDP carried by the incident light is formed by the lens LZ ₂₁ and the lens LZ ₂₂ (see FIG. 8B). The image is formed by the imaging device PRD ₂ (see FIG. 8B) of the second imaging unit 210B ₂ described above.

(When the road surface is a specular reflection surface)
Figure 10 (A) is a road surface RDP is flooded state, when the road surface RDP is a specular surface, an example of a state of reflection on the road surface RDP in when illuminated by the first illumination unit 120B ₁ It is indicated by a thick arrow. As shown in FIG. 10A, when the road surface RDP is a specular reflection surface, when the first illumination unit 120B ₁ illuminates the light emitted from the first illumination unit 120B _{1 on the} road surface RDR. specularly reflected, most of incident on the first imaging unit 210B _1. The imaging an image of the imaging target region of the road surface RDP incident light is played is being imaged by the first imaging optical system of the imaging unit 210B _1, the imaging result by the imaging device PRD ₁ of the first imaging unit 210B ₁ Is done.

FIG. 10B shows the state of reflection on the road surface RDP when illuminated by the second illuminating unit 120B ₂ when the road surface RDP is a specular reflection surface as in the case of FIG. 10A. An example is indicated by a thick arrow. As shown in FIG. 10B, when the road surface RDP is a specular reflection surface, when the second illumination unit 120B ₂ illuminates the light emitted from the second illumination unit 120B _{2 on the} road surface RDR. specularly reflected, most of incident on the second imaging unit 210B _2. The imaging an image of the imaging target region of the road surface RDP incident light is played is being imaged by the second imaging optical system of the imaging unit 210B _2, the imaging result by the imaging device PRD ₂ of the second imaging unit 210B ₂ Is done.

As described above, even road RDP is in either case the diffuse reflection surface and specular reflective surface, by illumination with the first illuminating portion 120B ₁ and the second illumination unit 120B _2, the imaging of the imaging target region on the road surface RDP Is possible. However, when the road surface RDP is a specular reflection surface, the brightness of the pixels of the captured image may differ depending on the polarization direction of the illumination light. Therefore, whether the illumination by the first illumination unit 120B _1, or mobile depending on whether it is illuminated by the second illumination unit 120B _2, different sharpness of the captured image, relative to the road surface RDP by using a so-called displacement search method There may be cases where the number that can be extracted as the feature region in the image for matching when detecting the body speed is different.

Even when the road surface RDP is in a snowy state, the road surface RDP becomes a diffuse reflection surface. In this case, the intensity of the reflected light on the road surface RDP is higher than when the road surface RDP is in a dry state.

Further, when the road surface RDP is in a frozen state, the reflected light on the road surface RDP is shown in FIG. 9 (A) and FIG. 10 (A), or FIG. 9 (B) and FIG. 10 (B). It becomes an intermediate state.

<Operation>
Next, the operation of the speed detection device 100B configured as described above will be described mainly focusing on the speed detection process executed by the relative speed output unit 113B.

Initially, it is assumed that the illumination switching unit 112 sets both the illumination designation LC ₁ and the illumination designation LC ₂ to “OFF”.

When starting the speed detecting process, as shown in FIG. 11, first, the relative velocity output unit 113B generates the illumination switch control LSC _1, and sends the generated illumination switch controlling LSC ₁ to the lighting switch unit 112. Upon receiving this illumination switching control LSC ₁ , the illumination switching unit 112 sets the illumination designation LC ₁ to “ON” and sends it to the first illumination unit 120B _1, and sets the illumination designation LC ₂ to “OFF” and the second illumination unit. send to 120B _2. As a result, the illumination light only from the first illuminating portion 120B ₁ is injected, the road surface is illuminated by illumination light the injection.

Subsequently, the relative speed output unit 113B sends an imaging command IMC ₁ to the first imaging unit 210B ₁ . Consequently, imaging of the road by the first imaging unit 210B ₁ is performed, the imaging results, as captured image data IMD _{1, 1,} is sent to the speed detecting device 100B.

The relative speed output unit 113B receives the captured image data IMD _1,1 via the acquisition unit 111B. Then, the relative speed output unit 113B extracts the characteristics of the feature region and the position in the image in the captured image corresponding to the captured image data IMD _1,1 .

Further, the relative speed output unit 113B obtains the sharpness CT _{1,1 of the} captured image. In the second embodiment, as in the case of the first embodiment, the relative speed output unit 113B obtains the standard deviation of the brightness of the pixels of the captured image as the sharpness of the captured image. The sharpness required in this way increases as the value increases.

Next, when the elapsed time from the issuance processing of the illumination switching control LSC ₁ corresponding to the captured image data IMD _1,1 reaches the time TPB / 2, the relative speed output unit 113B again outputs the imaging command IMC ₁ to the first imaging. send to part 210B _1. Consequently, imaging of the road by the first imaging unit 210B ₁ is performed, the imaging results, as captured image data IMD _{1, 2,} is sent to the speed detecting device 100B.

The relative speed output unit 113B receives the captured image data IMD _1,2 via the acquisition unit 111B. Then, the relative velocity output unit 113B is configured to extract the characteristics and image position of the characteristic region in the captured image corresponding to the captured image data IMD _{1, 2,} obtaining the sharpness CT _{1, 2} of the captured image.

Next, the relative speed output unit 113B specifies a common feature region between the feature region in the captured image corresponding to the captured image data IMD _1,2 and the feature region in the captured image corresponding to the captured image data IMD _1,1. . Then, the relative speed output unit 113B calculates the number NC ₁ of the specified common specific areas. Subsequently, the relative speed output unit 113B calculates the average of the above-described sharpness CT _1,1 and sharpness CT _1,2 as the sharpness CT ₁ of the captured image at the time of illumination by the first illumination unit 120B ₁ .

Next, when the elapsed time from the issuance processing of the illumination switching control LSC ₁ corresponding to the captured image data IMD _1,1 and IMD _1,2 reaches the time TPB, the relative speed output unit 113B generates the illumination switching control LSC ₂ . Then, the generated illumination switching control LSC ₂ is sent to the illumination switching unit 112. Upon receiving this illumination switching control LSC ₂ , the illumination switching unit 112 sets the illumination designation LC ₁ to “OFF” and sends it to the first illumination unit 120 B _1, and sets the illumination designation LC ₂ to “ON” and the second illumination unit. send to 120B _2. As a result, the illumination light only from the second illumination unit 120B ₂ is emitted, the road surface is illuminated by illumination light the injection.

Subsequently, the relative speed output unit 113B sends an imaging command IMC ₂ to the second imaging unit 210B ₂ . Consequently, imaging of the road by the second imaging unit 210B ₂ is performed, the imaging results, as captured image data IMD _2,1, sent to the speed detecting device 100B.

The relative speed output unit 113B receives the captured image data IMD _2,1 via the acquisition unit 111B. Then, the relative velocity output unit 113B extracts the characteristics of the feature region and the position in the image in the captured image corresponding to the captured image data IMD _2,1 , and obtains the sharpness CT _{2,1 of the} captured image.

Next, when the elapsed time from the issue processing of the imaging command IMC ₂ corresponding to the captured image data IMD _2,1 reaches the time TPB / 2, the relative speed output unit 113B again sends the imaging command IMC ₂ to the second imaging unit. send to 210B _2. Consequently, imaging of the road by the second imaging unit 210B ₂ is performed, the imaging results, as captured image data IMD _{2, 2,} is sent to the speed detecting device 100B.

The relative speed output unit 113B receives the captured image data IMD _2,2 via the acquisition unit 111B. Then, the relative speed output unit 113B extracts the characteristics of the feature region and the position in the image in the captured image corresponding to the captured image data IMD _2,2 , and obtains the sharpness CT _{2,2 of the} captured image.

Next, the relative speed output unit 113B specifies a common feature region between the feature region in the captured image corresponding to the captured image data IMD _2,2 and the feature region in the captured image corresponding to the captured image data IMD _2,1. . Then, the relative speed output unit 113B calculates the number NC ₂ of the specified common specific areas. Subsequently, the relative velocity output unit 113B is the average of the sharpness CT _2,1 and sharpness CT _{2, 2} described above is calculated as the sharpness CT ₂ of the captured image during illumination by the second illumination unit 120B _2.

Next, the relative speed output unit 113B calculates the moving body speed V according to the following equation (2) instead of the above equation (1), except that the relative velocity in the first embodiment described above. The calculation process of the moving body speed V similar to that of the output unit 113A is performed. Then, the relative speed output unit 113B outputs the calculated moving body speed V to the control device 220 as the relative speed information VLI.
V = (2 · ΔD) / (m · TPB) (2)

Thereafter, whenever the time TPB elapses from the issuance of the illumination switching control LSC ₂ , the relative speed output unit 113B repeats the processing from the issuance of the illumination switching control LSC ₁ to the calculation of the moving body speed V. As a result, the moving body speed V is calculated every time (2 · TPB), and is output to the control device 220 as the relative speed information VLI.

FIG. 12 illustrates an example of the moving body speed calculation process by the relative speed output unit 113B. In FIG. 12, similarly to the example shown in FIG. 6 described above, a common characteristic region is 2 region of the A area and the B area, based individual pixel movement amount of each of these 2 regions [Delta] D _A, the [Delta] D _B An example of calculating the moving body speed V is shown.

As described above, in the second embodiment, the illumination by the first illumination unit 120B ₁ for illuminating the road surface at different angles from each other, the illumination by the second illumination unit 120B _2, the relative velocity output unit 113B, the illumination switching unit The imaging unit 210B is controlled to perform imaging of the road surface while performing control to alternately switch every time TPB via 112. Subsequently, the relative speed output unit 113B illuminates corresponding to the captured image for calculating the relative speed information between the moving body MV and the road surface based on the image captured by the image capturing unit 210B obtained via the acquisition unit 111B. To decide. Then, the relative speed output unit 113B calculates relative speed information at each time point based on the determined captured image at the time of illumination by the illumination unit, and outputs the calculated relative speed information to the control device 220.

Therefore, according to the second embodiment, even if the road surface state changes every moment, the relative speed information between the moving body MV and the road surface can be detected with high accuracy.

In the second embodiment, the first illumination unit 120B ₁ performs illumination with P-polarized light, and the second illumination unit 120B ₂ performs illumination with S-polarized light. For this reason, it is possible to obtain a road surface image regardless of whether it is a diffuse reflection road surface or a specular reflection road surface, and to acquire an image with appropriate sharpness corresponding to a road surface having different reflection characteristics depending on the polarization direction of illumination light. Therefore, the relative speed information between the moving body MV and the road surface can be detected with high accuracy.

Further, in the second embodiment, the number of feature regions common between two captured images obtained at the time of successive illuminations by the same illumination unit is set to the case of illumination by the first illumination unit 120B _1. , compared with the case of the illumination by the second illumination unit 120B _2, based on the captured image at the time of lighting the number of common features area by a greater illumination unit, the relative speed information of the moving body MV and the road surface To detect. When the number of common feature areas is the same, the relative speed information between the moving body MV and the road surface is detected based on the captured image at the time of illumination by the illuminating unit having a higher sharpness of the captured image. Therefore, the relative speed information between the moving body MV and the road surface can be detected with high accuracy.

[Modification of Embodiment]
The present invention is not limited to the first and second embodiments described above, and various modifications are possible.

For example, in the first and second embodiments described above, the number of illumination units having different illumination characteristics is set to 2, but is set to 3 or more, and the illumination units that emit illumination light in time division are sequentially switched and moved at each time point. You may make it determine suitably the illumination part from which the captured image most suitable for calculation of body speed is obtained.

Moreover, in said 1st Embodiment, although it imaged once in the continuous illumination period by one illumination part, it is 2 in the continuous illumination period by one illumination part like said 2nd Embodiment. The moving body speed may be calculated by performing imaging for a number of times.

In the second embodiment, the imaging is performed twice in the continuous illumination period by one illumination unit. However, as in the first embodiment, 1 is performed in the continuous illumination period by one illumination unit. The moving body speed may be calculated by performing imaging for a number of times.

Further, in the first and second embodiments described above, based on the captured image at the time of illumination by the illuminating unit having a larger number of feature regions in common between two captured images that are temporally adjacent to each other, The relative speed information with the road surface was detected. Then, when the number of common feature areas is the same, relative speed information between the moving body and the road surface is detected based on the captured image at the time of illumination by the illumination unit with higher sharpness of the captured image. . On the other hand, without determining which illuminating part has a larger number of common feature areas, only the illuminating part with a higher sharpness of the captured image is determined and moved. You may make it detect the relative speed information of a body and a road surface.

In the first and second embodiments described above, determination of which illumination unit can illuminate more appropriately for detection of the moving body speed before calculating the moving body speed (hereinafter referred to as “preliminary determination”). Only) and the speed of the moving object was detected. On the other hand, whether or not the moving body speed detected from the captured image at the time of illumination by the lighting unit estimated as a result of the prior determination has a large discontinuity with respect to the detection result of the moving body speed so far The discontinuity determination may be performed. In this case, when the result of the discontinuity determination is affirmative, based on the captured image at the time of illumination by the illumination unit other than the illumination unit adopted based on the result of the prior determination, the moving body speed The detection may be redone.

In the first and second embodiments, the pixel movement amount is detected by a so-called displacement amount search method. However, the pixel movement amount may be detected by an image correlation method or a spatial filter method.

In the first and second embodiments, a telecentric optical system is employed as the optical system of the imaging unit. On the other hand, you may employ | adopt optical systems other than a telecentric optical system as an optical system of an imaging part.

In the first and second embodiments described above, it is assumed that the imaging unit is prepared outside the speed detection device. However, the speed detection device may include an imaging unit.

In the first and second embodiments, the entire speed detection device is mounted on the moving body. On the other hand, the control processing unit in the speed detection device may be installed outside the moving body, and connected to the imaging unit mounted on the vehicle, the control device, and a plurality of illumination units via a wireless communication network.

The control processing unit in the speed detection apparatus of the first and second embodiments described above is configured as a computer as a calculation unit including a central processing unit (CPU: Central Processing 等 Unit), and a program prepared in advance is configured. You may make it perform one part or all part of the function of the control processing part of said 1st and 2nd embodiment by performing with the said computer. This program is recorded on a computer-readable recording medium such as a hard disk, CD-ROM, or DVD, and is loaded from the recording medium and executed by the computer. The program may be acquired in a form recorded on a portable recording medium such as a CD-ROM or DVD, or may be acquired in a form distributed via a network such as the Internet. Also good.

Claims (12)

1. An acquisition unit for acquiring a captured image obtained by an imaging unit mounted on a moving body imaging an imaging target;
   A plurality of illumination units that illuminate the imaging object at different angles;
   An illumination switching unit that sequentially switches one illumination unit that illuminates the imaging target at predetermined time intervals;
   A relative speed information output unit that outputs information on a relative speed between the imaging target and the imaging unit based on the captured image acquired by the acquisition unit;
   A speed detection device comprising:
2. The speed detection device according to claim 1, wherein an optical axis of illumination light emitted from one of the plurality of illumination units is coincident with an optical axis of an optical system in the imaging unit.
3. 2. The speed according to claim 1, wherein an optical axis of illumination light emitted from each of the plurality of illumination units is oblique to an optical axis of an optical system in the imaging unit. Detection device.
4. The speed detection device according to claim 1, wherein polarization characteristics of illumination light emitted from each of the plurality of illumination units are different from each other.
5. The imaging object is a road surface,
   The optical axis of the optical system of the imaging unit is orthogonal to the road surface,
   The speed detection apparatus according to claim 1, wherein:
6. The speed detection apparatus according to claim 1, wherein the imaging unit performs imaging once for each predetermined time interval.
7. The speed detection apparatus according to claim 1, wherein the imaging unit performs imaging twice at the predetermined time interval.
8. The relative speed information output unit relates to the relative speed based on a captured image obtained in an illumination period by an illuminating unit having a larger number of common feature image areas between two captured images that are close in time. Output information,
   The speed detection apparatus according to claim 1, wherein:
9. The relative speed information output unit outputs information on the relative speed based on a captured image obtained in an illumination period by a lighting unit having a higher image sharpness.
   The speed detection apparatus according to claim 1, wherein:
10. A speed detection method used by a speed detection apparatus including a plurality of illumination units that illuminate an imaging target at different angles,
    An illumination switching step of sequentially switching one illumination unit that illuminates the imaging target at a predetermined time interval;
    An acquisition step in which an imaging unit mounted on a moving body acquires a captured image obtained by imaging the imaging target;
    A relative speed information output step for outputting information on a relative speed between the imaging target and the imaging unit based on the captured image acquired in the acquisition step;
    A speed detection method comprising:
11. A speed detection program causing a computer included in the speed detection apparatus to execute the speed detection method according to claim 10.
12. 12. A recording medium in which the speed detection program according to claim 11 is recorded so as to be readable by a computer included in the speed detection device.

Images