External recognition device

Abstract

Provided is an external environment recognition device that accurately determines a situation in which a function (driver assistance control) should be temporarily stopped, and determines such situation as a HALT situation and stops the function if image degradation is severe, such as in heavy rain, and does not determine such situation as a HALT situation and does not stop the function if the image degradation is mild, such as in light rain. An image feature value immediately after wiper wiping is saved and the rate of decrease from a current image feature value is calculated, and if the rate of decrease is greater than a standard value and becomes greater than the standard value multiple times cyclically, the function (driver assistance control) of a recognition unit (4) is temporarily stopped.

Description

[Technical field]

[0001] The present invention relates to an external environment recognition device such as an in-vehicle stereo camera, and more particularly to an external environment recognition device that accurately performs a stop determination for driving assistance control using an image captured by an in-vehicle camera. [Background technology]

[0002] There are known driving assistance controls such as adaptive cruise control (ACC) and automatic emergency braking (AEB). These controls recognize the surrounding environment (external world) from images captured by a camera installed in the windshield with the subject in front of the vehicle, and control the vehicle.

[0003] In the above driving assistance control, if the camera's visibility is obstructed by heavy rain or fogging of the windshield, etc., and the image deteriorates, non-detection or false detection occurs, resulting in operations such as no braking in AEB, false acceleration during ACC, false braking in AEB, and false braking during ACC. Therefore, a HALT function is required that temporarily stops the driving assistance control before it causes such operations and notifies the user that it has been temporarily stopped. However, if the driving assistance control is temporarily stopped, it will not be possible to reduce the burden of driving operations on the driver, so it is desirable to accurately determine the situation in which the driving assistance control should be temporarily stopped.

[0004] Patent document 1 describes that in order to accurately determine a situation in which driving assistance control should be temporarily stopped, the difference in edge or brightness is calculated from the first and second captured image data while the wipers are operating, and if the difference is equal to or greater than a specified value, the stop determination process is not performed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-088047 A Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, the stop determination process uses the number of edges, the number of distance data, and the brightness in the current frame, but the stop determination (image deterioration determination) is performed using only the information in the current frame, and it is not possible to determine whether the environment is originally one in which brightness and edges are difficult to produce, or whether brightness and edges are not produced due to image deterioration caused by heavy rain, etc. In that case, if there is slight deterioration of the image due to raindrops or snow on the road in an environment in which brightness and edges are originally difficult to produce, such as a snowy road, the system will erroneously determine that the system is HALT and stop the function (driving assistance control).

[0007] Therefore, the present invention aims to provide an external environment recognition device that judges the device to be HALT and halts its functions when the image degradation is severe, such as in heavy rain, and does not judge the device to be HALT and halt its functions when the image degradation is minor, such as in light rain. [Means for solving the problem]

[0008] In order to solve the above problems, one representative external environment recognition device of the present invention is characterized by having a camera mounted in a vehicle cabin, an image feature calculation unit that calculates image features from an image acquired by the camera, a recognition unit that recognizes objects outside the vehicle from an image acquired by the camera, a memory that stores a first image feature in a first image acquired at a timing determined in a predetermined cycle, and a function stop determination unit that determines whether to temporarily suspend the function of the recognition unit based on the first image feature or a comparison result between the first image feature and a second image feature in a current image. Effect of the Invention

[0009] According to the present invention, by making a judgment using time series data, it is possible to judge whether the environment is originally one in which image features such as parallax are difficult to appear, or image features such as parallax are not appearing due to image degradation caused by heavy rain, etc., so that when image degradation is severe, such as heavy rain, it is judged as HALT and the function is stopped, and when image degradation is light rain, where image degradation is mild, no HALT judgment is made and the function is not stopped. Therefore, when image degradation is severe, such as heavy rain, the function (driving assistance control) is temporarily stopped, whereas when image degradation is light rain, where image degradation is mild and not severe enough to HALT, the function (driving assistance control) is not stopped, and driving assistance can be continued to reduce the burden of driving operations on the driver.

[0010] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a configuration diagram of an in-vehicle stereo camera according to an embodiment of the present invention. [Diagram 2] An explanatory diagram of (a) a left camera image, (b) a right camera image, and (c) a disparity image under normal conditions. [Diagram 3] An explanatory diagram of (a) the left camera image, (b) the right camera image, and (c) the disparity image when raindrops are attached. [Figure 4A] FIG. 4 is an explanatory diagram of a wiper position before the wiper is operated. [Figure 4B] FIG. 11 is an explanatory diagram of the wiper position immediately after wiping with the wiper. [Figure 5A] FIG. 11 is an explanatory diagram of a camera image taken before the wipers are operated. [Figure 5B] FIG. 11 is an explanatory diagram of a camera image taken immediately after wiping with a wiper. [Figure 6] 5 is a flowchart of a function stop determination unit of the in-vehicle stereo camera. [Figure 7A] An image of the behavior of this system's stoppage judgment during heavy rain, and an explanatory diagram of the time series change in the disparity number. [Figure 7B] An image of the behavior of this system's shutdown judgment during heavy rain, and an explanatory diagram of the results of deterioration judgment in each frame. [Figure 7C] This is an image of the behavior of this system's shutdown judgment during heavy rain, and an explanatory diagram of the HALT occurrence counter. [Figure 8A] This is an image of the behavior of the system's stop judgment during light rain, and an explanatory diagram of the time series change in the disparity number. [Figure 8B] This is an image of the behavior of the system's shutdown judgment during light rain, and an explanatory diagram of the results of deterioration judgment in each frame. [Figure 8C] This is an image of the behavior of the system's stop judgment during light rain, and an explanatory diagram of the HALT occurrence counter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the drawings.

[0013] FIG. 1 is a representative diagram of this embodiment, and is a configuration diagram of an in-vehicle stereo camera in this embodiment. The in-vehicle stereo camera 1 is mounted on a vehicle and has a function as an external recognition device that recognizes objects outside the vehicle from images acquired (captured) by (multiple) cameras attached inside the vehicle cabin, and realizes driving assistance functions such as ACC and AEB. The in-vehicle stereo camera 1 is composed of cameras 2A, 2B (left camera 2A, right camera 2B) as a pair of left and right imaging units, an image feature amount calculation unit 3, a recognition unit 4, a memory 5 that stores a first image feature amount, and a function stop determination unit 6. The in-vehicle stereo camera 1 is composed of hardware such as cameras, a CPU, memories, and electronic circuits. The system is equipped with a driver assistance system (DAS) and software that cooperates with the hardware to provide vehicle driving assistance.

[0014] The cameras 2A and 2B in Fig. 1 capture images. The cameras 2A and 2B are fixed to the vehicle so as to be spaced apart in the vehicle width direction, and capture images of the front through the windshield of the vehicle, so that they can capture the same area.

[0015] The recognition unit 4 in FIG. 1 detects and recognizes objects such as vehicles and pedestrians in the surrounding environment (here, ahead) from images acquired by the cameras 2A and 2B, and realizes driving assistance functions such as ACC and AEB.

[0016] The image feature amount calculation unit 3 receives an image captured by the left camera 2A (hereinafter also referred to as a left camera image) and an image captured by the right camera 2B (hereinafter also referred to as a right camera image) as input, and calculates image feature amounts by analyzing pixel values ​​(luminance values) in the images. The image feature amount may be calculated using the pixel values ​​themselves, or may be calculated by defining a local region from multiple pixels and using the average luminance, weighted average luminance, representative luminance, or the like within the local region. In this example, the image feature amount calculation unit 3 calculates the number of parallaxes and the number of edges as image feature amounts.

[0017] The number of edges in an image can be calculated from (the image from) the left camera 2A or the right camera 2B in the current frame using a known technique.

[0018] Disparity is calculated by detecting corresponding points in the images of the left and right cameras 2A and 2B through pattern matching, and calculating the coordinate shift between the detected corresponding points. Using this disparity, the distance to the corresponding point in real space can be calculated according to the principle of triangulation. Figure 2 shows an image of disparity calculation in the image feature amount calculation unit 3. In Figure 2, a disparity image (c) is calculated by pattern matching the left camera image (a) and the right camera image (b). Disparity is calculated in areas where edges appear, such as people, white lines, and preceding vehicles, but disparity cannot be calculated in areas where edges are difficult to see, such as the sky, making pattern matching difficult. The number of valid disparities calculated in the entire disparity image in areas where edges appear is called the disparity number.

[0019] Figure 3 shows an example of the case where raindrops have adhered to the left camera (specifically, the windshield in the field of view of the left camera) as in the left camera image (a) in Figure 3. When raindrops have adhered to the left camera (specifically, the windshield in the field of view of the left camera), the captured image of the surrounding environment is distorted or hidden by the raindrops, making pattern matching with the right camera image (b) difficult, and the overall disparity number decreases as shown in the disparity image (c).

[0020] The memory 5 stores the first image feature amount of the first image acquired by the image feature amount calculation unit 3. The first image for calculating the first image feature amount is acquired at a timing determined by a predetermined cycle defined by the wiper wiping. Figures 4A and 4B and Figures 5A and 5B show the wiper position and the camera image immediately after the wiper wiping. In Figures 4A and 4B, 2A and 2B are the left and right cameras, 10 is the windshield, and 11A and 11B are the left and right wipers.

[0021] FIG. 4A is an image before the wipers are operated. In rainy weather, raindrops adhere to the windshield in front of the camera, and the image obtained from the camera is as shown in FIG. 5A. On the other hand, FIG. 5B is an image immediately after the wipers are wiped. As shown in FIG. 4B, the wipers 11A and 11B both pass in front of the left and right cameras to wipe off the raindrops adhering to the windshield, and a clear image as shown in FIG. 5B can be obtained. This is defined as immediately after the wipers are wiped. For example, in a typical vehicle, the wipers 11A and 11B operate (rotate) in one direction (clockwise in the example shown in FIG. 4A and B) on the windshield from the position before the wipers are operated (normal or stored position) as shown in FIG. 4A. Then, after reaching the position furthest from the position before the wipers are operated (positions AA and BB in FIG. 4B), they operate (rotate) in the opposite direction (counterclockwise in the example shown in FIG. 4A and B) on the windshield, and return to the position before the wipers are operated (normal or stored position) as shown in FIG. 4A. By repeatedly performing such a series of operations once or a plurality of times, raindrops adhering to the windshield are wiped away. In such a vehicle, the wipers 11A and 11B pass in front of the left camera 2A and the right camera 2B twice (twice in one direction and the other direction) during the series of operations. Depending on the installation position of the camera and the wiping range (operation range) of the wipers, the wipers 11A and 11B may pass in front of the left camera 2A twice (four times in total for the wipers 11A and 11B) or the wipers 11A and 11B may pass in front of the right camera 2B twice (four times in total for the wipers 11A and 11B). In general, it is considered that the wiper wiping is completed during the series of operations when the wipers 11A and 11B pass in front of the left camera 2A and the right camera 2B twice in one direction and the other direction (not once in one direction). Therefore, in the series of operations described above, the time immediately after wipers 11A and 11B pass completely in front of the left camera 2A and the right camera 2B for the second time (in other words, immediately after passing in one direction and then in the other direction) is defined as immediately after wiper wiping.

[0022] In addition, in this embodiment, the timing of the wiper wiping operation can be a reference for the timing of function stop determination (image deterioration determination). Therefore, the period from immediately after the wiper wiping in one series of operations to immediately after the wiper wiping in the next series of operations is defined as the operation cycle (drive cycle) of the wipers 11A and 11B. In other words, the period from when the wipers 11A and 11B move (rotate) on the windshield from the position before the wiper operation to when they return to the position before the wiper operation can also be defined as the operation cycle of the wipers 11A and 11B. In other words, a predetermined timing in the series of operations of the wiper wiping operation can be set as a reference timing, and the period from a predetermined timing in one series of operations to a predetermined timing in the next series of operations can also be defined as the operation cycle of the wipers 11A and 11B.

[0023] Whether or not it is immediately after wiping with the wipers can be determined from the camera image, the wiper motor signal, the wiper drive cycle, the signal from the raindrop sensor, etc. The image feature amount calculation unit 3 overwrites and saves the image feature amount of the image immediately after wiping with the wipers in the memory 5 as the image feature amount of the first image.

[0024] The function stop determination unit 6 in FIG. 1 compares the image feature amount in the current frame (image) acquired by the image feature amount calculation unit 3 as a second image feature amount with the first image feature amount stored in the memory 5 to determine whether or not to stop the function (the driving assistance function of the recognition unit 4).

[0025] Next, a specific operation of the function stop determination unit 6 of the above-mentioned vehicle-mounted stereo camera 1 will be described with reference to Fig. 6. Fig. 6 is a flowchart showing the procedure of the function stop determination unit 6 of the vehicle-mounted stereo camera 1 according to this embodiment.

[0026] First, in S101, it is determined whether the wiper is in operation, and if the wiper is in operation, the process proceeds to S102. If the wiper is not in operation, the function stop determination is terminated. In order to determine whether the wiper is in operation, a wiper switch signal or the like is acquired.

[0027] In S102, the first image feature amount immediately after wiping the image stored in the memory 5 is compared with the second image feature amount, which is the number of features in the current frame, to obtain a reduction rate d. is f1 and the second image feature is f2, the reduction rate d [%] is calculated by the following formula (1). [Number 1] d = ( f1 - f2 ) ÷ f1 × 100 ···(1)

[0028] In S103, it is determined whether the decrease rate d is greater than a reference value dTH. If it is greater than the reference value dTH, the current frame is determined to be degraded, and the counter value of the HALT occurrence counter is incremented in S104. If it is less than the reference value dTH, the current frame is determined to be non-degraded, and the counter value of the HALT occurrence counter is decremented in S105.

[0029] In S106, it is determined whether or not to halt (HALT) the camera function based on the counter value of the HALT occurrence counter calculated in S104 and S105. If the counter value is equal to or greater than the reference value, the process proceeds to S107, where the camera function is halted (HALT). In this state, the driving assistance function performed by the recognition unit 4 is temporarily stopped.

[0030] Next, the specific behavior of the above flow will be described with reference to FIGS. 7A, 7B, and 7C, and FIGS. 8A, 8B, and 8C.

[0031] 7A, 7B, and 7C are conceptual diagrams of behavior in a heavy rain scene. FIG. 7A is a graph showing the time series change in the number of parallaxes. In the case of heavy rain, the image is clear immediately after the wiper is wiped (▲) so the number of parallaxes reaches a peak (see FIG. 5B). After that, the number of parallaxes decreases because raindrops gradually adhere to the windshield in front of the camera until the next wiper is wiped (see FIG. 5A). The number of parallaxes increases again immediately after the next wiper is wiped, and the same behavior is repeated thereafter. FIG. 7B shows the results of the degradation judgment for each frame, representing the judgment result of S103. In the graph of FIG. 7B, the cases judged as degraded in S104 are shown as 1, and the cases judged as not degraded in S105 are shown as 2. In the case of heavy rain, the rate of decrease in the number of disparities increases, so degradation (1) and non-degradation (0) are repeated periodically. In the case of FIG. 7B, the counter value repeatedly increases and decreases by periodically repeating degradation (the rate of decrease in the number of disparities periodically exceeds the reference value multiple times) and non-degradation (the rate of decrease in the number of disparities periodically becomes equal to or less than the reference value multiple times). In this example, the increased value is made larger compared to the decreased value in each frame. Here, the counter value is compared with the reference value (S106), and if the counter value exceeds the reference value, the camera function is temporarily stopped (HALT) (S107). This temporarily stops the driving assistance function performed by the recognition unit 4 before it fails to operate or malfunctions.

[0032] Figures 8A, 8B, and 8C are conceptual diagrams of the behavior of light rain in an environment where parallax (or edges) are difficult to produce, such as snowfall. Figure 8A is a graph showing the time series change in the number of parallaxes. In the case of light rain, as with heavy rain, the image is clear immediately after wiping the wiper (▲) (see Figure 5B), so the number of parallaxes reaches a peak and then decreases, but the rate of decrease is small. Figure 8B shows the results of the degradation judgment for each frame, representing the result of the judgment in S103. In the case of light rain, the rate of decrease in the number of parallaxes is not large, so it is judged to be non-degraded (0). Figure 8C shows the HALT occurrence counters in S104 and S105. Since it is non-degraded, the counter value decreases (specifically, the counter value is 0 or more). (Since the counter value is the same as the reference value, the counter value does not change and remains flat.) Here, the counter value is compared with the reference value (S106), and the counter value falls below the reference value. This allows the driving assistance function performed by the recognition unit 4 to be continued without stopping, thereby continuing to reduce the burden of driving operations on the driver.

[0033] In this way, the function stop determination unit 6 calculates the rate of reduction in the number of parallaxes by comparing the current frame with the frame immediately after the wiper has been wiped (when the wiper has completely passed in front of the left and right cameras and the image is clearly displayed) as a reference frame, and can determine whether the environment is one in which parallax is unlikely to occur in the first place, or whether parallax is not occurring due to image degradation caused by heavy rain, etc. (in other words, it is possible to distinguish between environments in which parallax is unlikely to occur in the first place, such as normal rain and snow accumulation).

[0034] In the above embodiment, the HALT occurrence counter is used to determine whether the function has stopped, but another method may be used that captures the periodic change in the number of disparities as shown in Fig. 7A. For example, the function may be determined based on the periodic change (periodicity) in the rise interval or fall interval of the degradation determination result for each frame as shown in Fig. 7B.

[0035] In the above embodiment, the timing for determining whether the function has stopped is determined by comparing the current frame with the time immediately after the wiper has been wiped (when the wiper has completely passed in front of the left and right cameras and the image is clearly captured) as a reference, and calculating the reduction rate of the image feature amount of the current frame relative to the image feature amount of the image immediately after the wiper has been wiped. However, the timing for determining whether the function has stopped is not limited to the above embodiment.

[0036] For example, the function stop may be determined by comparing the current frame with a reference frame immediately after the wiper is wiped (or a reference frame number of frames) and calculating a decrease rate of the image feature amount. Alternatively, the function stop may be determined by comparing the current frame with a reference frame immediately before the wiper is wiped (an image state in which the parallax is less likely to occur immediately before the wiper is wiped) and calculating an increase rate of the image feature amount of the current frame relative to the image feature amount of the image immediately before the wiper is wiped. Alternatively, the function stop may be determined by comparing the current frame with a frame immediately before the wiper is wiped (or a frame a reference frame a predetermined time before the current frame (or a predetermined number of frames before the current frame) (in other words, a frame immediately before the wiper is wiped or a frame a predetermined time after the wiper is wiped), and calculating a change rate (decrease rate or increase rate) of the image feature amount. The predetermined time (or a predetermined number of frames) used in the determination here may be specified based on the wiper operation cycle (for example, the period from immediately after one wiper wipe to immediately after the next wiper wipe).

[0037] In other words, the function stop determination unit 6 of this embodiment is capable of determining whether a function has stopped by identifying two different points (two times) in the wiper's operating cycle and calculating the rate of change (rate of decrease or rate of increase) in the image features at those two different points (two times) in the wiper's operating cycle.

[0038] Furthermore, in the above embodiment, the function stoppage is determined using the rate of change of the first and second image features, but the function stoppage may also be determined, for example, based on the result of a comparison between the absolute values ​​of the first and second image features.

[0039] As explained above, with conventional technology, it is not possible to determine whether an environment is one in which image features such as parallax are difficult to produce in the first place, or whether image features such as parallax are not produced due to image degradation caused by heavy rain, etc. In such a case, when an environment in which image features such as parallax are difficult to produce in the first place, such as a snowy road, causes minor degradation of the image due to raindrops or snow adhering to the image, the system will erroneously determine that the system is HALT and stop the function (driving assistance control).

[0040] If image features such as parallax are no longer visible due to image degradation (distortion of the entire screen) caused by heavy rain, etc., and the function (driving assistance control) is temporarily stopped due to HALT, the user will not feel uncomfortable. On the other hand, if image features such as parallax are difficult to see on snowy roads, etc., and image features such as parallax are no longer visible due to slight degradation of the image caused by raindrops (distortion of part of the screen), and the function (driving assistance control) is temporarily stopped due to HALT, the user will feel uncomfortable. In other words, if slight degradation not enough to cause HALT occurs in the image in a place where image features such as parallax are difficult to see (snowy roads or pitch black roads), and HALT is accidentally triggered and the function (driving assistance control) is temporarily stopped, the user will feel uncomfortable.

[0041] For this reason, it is important to determine whether the environment is one in which image features such as parallax are difficult to bring out in the first place, or whether image features such as parallax are not coming out due to image degradation caused by heavy rain, etc., and to accurately determine the situation in which the function (driving assistance control) should be temporarily stopped. In cases where the image degradation is severe, such as heavy rain, it is important to make a HALT judgment and stop the function, and in cases where the image degradation is only mild, such as light rain, it is important to not make a HALT judgment and not stop the function.

[0042] The in-vehicle stereo camera (external environment recognition device) 1 of the present embodiment described above includes cameras (left camera 2A, right camera 2B) installed inside the vehicle cabin, an image feature amount calculation unit 3 that calculates image feature amounts (parallax number, edge number, etc.) from images acquired by the cameras, a recognition unit 4 that recognizes objects outside the vehicle from images acquired by the cameras, a memory 5 that stores a first image feature amount in a first image acquired at a timing determined in a predetermined cycle (a timing determined by the operation of wipers 11A and 11B), and a function stop determination unit 6 that determines whether or not to temporarily suspend the function of the recognition unit 4 (HALT determination) based on the first image feature amount or a comparison result between the first image feature amount and a second image feature amount in a current image.

[0043] More specifically, the in-vehicle stereo camera (external environment recognition device) 1 of this embodiment saves the image feature amount immediately after wiping with the wiper, calculates the decrease rate with respect to the current image feature amount, and temporarily stops the function of the recognition unit 4 if the decrease rate is greater than a reference value and if the decrease rate periodically becomes greater than the reference value multiple times.

[0044] According to this embodiment, by making a judgment using time series data (for example, two time series frames based on the time immediately after wiping the wiper), it is possible to judge whether the environment is originally such that image features such as parallax are difficult to appear, or image features such as parallax are not appearing due to image deterioration caused by heavy rain, etc., so that when the image deterioration is severe, such as heavy rain, it is judged as HALT and the function is stopped, and when the image deterioration is light rain, the HALT judgment is not made and the function is not stopped. Therefore, when the image deterioration is severe, such as heavy rain, the function (driving assistance control) is temporarily stopped, while when the image deterioration is light rain, which is not enough to HALT, the function (driving assistance control) is not stopped, and driving assistance can be continued to continue reducing the burden of driving operations on the driver.

[0045] The present invention is not limited to the above-mentioned embodiment, and various modifications are included. For example, the above-mentioned embodiment has been described in detail to easily explain the present invention, and is not necessarily limited to those having all the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. In addition, each of the above-mentioned configurations, functions, processing units, processing means, etc. may be realized by hardware, for example, by designing them as integrated circuits. In addition, each of the above-mentioned configurations, functions, etc. may be realized by software by a processor interpreting and executing a program that realizes each function. Information such as a program, table, file, etc. that realizes each function can be placed in a memory, a recording device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD. [Explanation of symbols]

[0046] 1...In-vehicle stereo camera (external recognition device) 2A, 2B...Camera (imaging unit) (2A: left camera, 2B: right camera) 3...Image feature calculation section 4...Recognition part 5. Memory 6...Functional outage determination section 10. Windshield 11A, 11B…Wiper

Claims

1. A camera installed inside the vehicle, an image feature amount calculation unit that calculates an image feature amount from the image captured by the camera; A recognition unit that recognizes an object outside the vehicle from the image acquired by the camera; a memory that stores a first image feature amount in a first image acquired at a timing determined in a predetermined cycle; a function stop determination unit that determines whether or not to suspend a function of the recognition unit based on the first image feature amount or a comparison result between the first image feature amount and a second image feature amount in a current image; having the memory for storing the first image feature amount stores an image feature amount captured at a timing defined by the operation of a wiper; the function stop determination unit determines whether or not to suspend the function of the recognition unit based on a rate of change in the image feature amount between two time series points in an operation cycle of the wiper; The function stop determination unit calculates a rate of change of the second image feature relative to the first image feature from the first image feature immediately before wiping by the wiper stored in the memory and the second image feature in the current image, and stops the function of the recognition unit if the rate of change is greater than a reference value, and does not stop the function of the recognition unit if the rate of change is equal to or less than the reference value.

2. The external environment recognition device according to claim 1, The external environment recognition device is characterized in that the first image is acquired at a timing defined by the operation of a wiper.

3. The external environment recognition device according to claim 1, The external environment recognition device, wherein the image feature calculation unit sets the number of parallaxes calculated from two or more cameras in the current frame as the image feature.

4. The external environment recognition device according to claim 1, The external environment recognition device, wherein the image feature calculation unit sets the number of edges calculated from one camera in the current frame as the image feature.

5. The external environment recognition device according to claim 1, The external environment recognition device, wherein the function stop determination unit stops the function of the recognition unit when the rate of change periodically becomes greater than a reference value multiple times.

6. The external environment recognition device according to claim 1, The function stop determination unit determines whether to temporarily suspend the function of the recognition unit based on a comparison result between absolute values ​​of the first image feature amount and the second image feature amount. The external environment recognition device.

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