Automotive electronic devices

Abstract

The purpose of the present invention is to provide an electronic device for vehicles that is capable of optimizing the frequency of rewriting, in a memory, a correction value for correcting optical axis deviation. An electronic device 1 for vehicles changes, on the basis of a change amount of a correction value for correcting optical axis deviation of cameras 11, 12 in image data taken by the cameras 11, 12, a rewriting frequency that is a frequency at which the correction value is stored in a memory 50. The electronic device 1 for vehicles may comprise the cameras 11, 12 and an image processing device 20. The image processing device 20 may have: the memory 50; an image data acquisition unit 31 that acquires the image data from the cameras 11, 12; a calibration unit 32 that carries out calibration including calculation of the optical axis deviation correction value; a calculation unit 33 that calculates the change amount of the calculated optical axis deviation correction value; a determination unit 34 that determines the rewriting frequency on the basis of the change amount of the calculated optical axis deviation correction value; and a control unit 35 that stores, in the memory 50, the optical axis deviation correction value in accordance with the determined rewriting frequency.

Description

[Technical Field]

[0001] The present invention relates to vehicle electronic devices. [Background technology]

[0002] In a stereo camera device, which is an electronic device for vehicles, optical axis misalignment occurs over time. Optical axis misalignment occurs when the central axis of the camera lens shifts from its initial position or when the central axes of the lenses of the left and right cameras shift. As the optical axis misalignment increases, the sensing accuracy of the stereo camera device deteriorates. Therefore, the stereo camera device periodically corrects the optical axis misalignment and stores the correction value for the optical axis misalignment in non-volatile memory to back up the correction value.

[0003] For example, Patent Document 1 discloses a camera calibration device including a parameter update unit that updates camera parameters stored in a parameter storage unit and also updates vehicle movement parameters. This parameter update unit has a function of finding optimal solutions for camera parameters and vehicle movement parameters so that the positions of feature points transformed by a homography matrix in an image from each camera are consistent with the flow of feature points found by a road surface flow extraction unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-107938 Summary of the Invention [Problem to be solved by the invention]

[0005] In a nonvolatile memory that stores correction values ​​for optical axis misalignment, it is necessary to consider that the number of times data can be rewritten over a lifetime does not exceed a rewrite limit. If the number of rewrites exceeds the rewrite limit, data corruption may occur in the nonvolatile memory, and there is a concern that the reliability of data retention in the nonvolatile memory may be impaired. The camera calibration device disclosed in Patent Document 1 does not take into consideration the frequency of rewriting camera parameters, and there is a concern that the memory rewrite limit may be exceeded.

[0006] The present invention has been made in view of the above, and has an object to provide an in-vehicle electronic device that can optimize the frequency at which correction values ​​for correcting optical axis misalignment are rewritten in memory. [Means for solving the problem]

[0007] In order to solve the above problem, the vehicle electronic device of the present invention is characterized in that the rewrite frequency, which is the frequency at which a correction value for correcting the optical axis misalignment of the camera in image data captured by the camera is stored in memory, is changed based on the amount of change in the correction value. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an electronic device for a vehicle that can optimize the frequency at which a correction value for correcting an optical axis deviation is rewritten in a memory. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing a configuration of an in-vehicle electronic device according to a first embodiment; [Figure 2] FIG. 10 is a diagram for explaining optimization of rewrite frequency. [Figure 3] 10 is a graph showing the transition of the optical axis deviation correction value when the amount of change in the optical axis deviation correction value is small. [Figure 4] 4 is a graph showing the relationship between the amount of change in the optical axis deviation correction value and the threshold value in the case shown in FIG. 3. [Figure 5] 10 is a graph showing the transition of the optical axis deviation correction value when the amount of change in the optical axis deviation correction value is large. [Figure 6] 6 is a graph showing the relationship between the amount of change in the optical axis deviation correction value and the threshold value in the case shown in FIG. 5. [Figure 7] 10 is a flowchart showing a process of optimizing a rewrite frequency according to the first embodiment. [Figure 8] 10 is a graph showing threshold values ​​set in a determination unit according to the second embodiment. [Figure 9] 11 is a graph showing an extension time function set in a determination unit according to the third embodiment. [Figure 10] 11 is a graph showing a time reduction function set in a determination unit according to the third embodiment. [Figure 11] FIG. 10 is a diagram showing the configuration of a vehicle electronic device according to a fourth embodiment. [Figure 12] 13 is a table for explaining optimization of rewrite frequency according to the fourth embodiment. [Figure 13] 10 is a graph showing an extension time function set in a determination unit according to the fourth embodiment. [Figure 14] 10 is a graph showing a time reduction function set in a determination unit according to the fourth embodiment. [Figure 15] 10 is a flowchart showing a process of optimizing the rewrite frequency according to the fourth embodiment. [Figure 16] 13 is a graph showing an extension time function set in a determination unit according to the fifth embodiment. [Figure 17] 13 is a graph showing a time reduction function set in a determination unit according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that components with the same reference numerals in each embodiment have the same functions in each embodiment unless otherwise specified, and description thereof will be omitted.

[0011] [Example 1] Fig. 1 is a diagram showing the configuration of an in-vehicle electronic device 1 according to Example 1. Fig. 2 is a diagram for explaining optimization of the rewriting frequency.

[0012] The in-vehicle electronic device 1 is a type of sensor device that is mounted on a vehicle and monitors the surroundings of the vehicle. The in-vehicle electronic device 1 is a sensor device that has an optical system such as a lens or a mirror. The in-vehicle electronic device 1 may be a monocular camera device or a stereo camera device equipped with multiple cameras. In this embodiment, the in-vehicle electronic device 1 will be described as a stereo camera device.

[0013] The vehicle electronic device 1 detects objects around the vehicle and measures the distance to the objects by utilizing the parallax of overlapping areas of image data captured by multiple cameras 11 and 12 arranged at a predetermined horizontal interval. The vehicle electronic device 1 shown in Figure 1 includes the cameras 11 and 12 and an image processing device 20 that processes the image data captured by the cameras 11 and 12.

[0014] The image processing device 20 is configured by a computer system including, for example, an arithmetic processing device 30 including a CPU, RAM, and ROM, a data storage device 40, and a memory 50. The image processing device 20 realizes various functions of the image processing device 20 by the CPU executing programs stored in the ROM.

[0015] 2, the arithmetic processing device 30 changes the frequency (hereinafter also referred to as the "rewrite frequency") of saving in the memory 50 correction values ​​(hereinafter also referred to as the "optical axis deviation correction values") for correcting the optical axis deviation of the cameras 11 and 12 in the image data captured by the cameras 11 and 12, based on the amount of change over time in the optical axis deviation correction values. Fig. 2 shows that when the optical axis deviation correction values ​​become smaller over time, the frequency of rewriting the optical axis deviation correction values ​​to the memory 50 is reduced over time.

[0016] The arithmetic processing device 30 includes an image data acquisition unit 31, a calibration unit 32, a calculation unit 33, a determination unit 34, and a control unit 35.

[0017] The image data acquisition unit 31 acquires image data from the cameras 11 and 12. The calibration unit 32 performs camera calibration, including calculation of an optical axis deviation correction value, using the image data acquired by the image data acquisition unit 31. The camera calibration can be performed by a known method. The calibration unit 32 stores the calculated optical axis deviation correction value in the data storage device 40. The data storage device 40 is configured by a volatile memory.

[0018] The calculation unit 33 calculates the amount of change in the optical axis deviation correction value stored in the data storage device 40. The determination unit 34 determines the rewriting frequency based on the amount of change in the optical axis deviation correction value calculated by the calculation unit 33. Details of the calculation unit 33 and the determination unit 34 will be described later with reference to FIGS.

[0019] The control unit 35 saves the optical axis deviation correction value stored in the data storage device 40 in the memory 50 according to the rewrite frequency determined by the determination unit 34. The memory 50 is configured by a nonvolatile memory. In particular, the memory 50 may be configured by a NAND-type nonvolatile memory. The NAND-type nonvolatile memory has fewer rewrite count limitations than the NOR-type memory, but is cheaper than the NOR-type memory.

[0020] 3 is a graph showing the transition of the optical axis deviation correction value when the amount of change in the optical axis deviation correction value is small, where the vertical axis represents the optical axis deviation correction value and the horizontal axis represents time.

[0021] time t n The optical axis deviation correction value at x(t n ) and time t n+1 The optical axis deviation correction value at x(t n+1 ), the change in the optical axis deviation correction value Δx is x(t n+1 ) and x(t n The calculation unit 33 calculates the amount of change Δx in the optical axis deviation correction value using equation (1). Δx=x(t n+1)-x(t n ) …(1)

[0022] Fig. 4 is a graph showing the relationship between the amount of change in the optical axis deviation correction value and the threshold value in the case shown in Fig. 3. The vertical axis of Fig. 4 represents the amount of change in the optical axis deviation correction value, and the horizontal axis of Fig. 4 represents time.

[0023] In Figure 4, time t n+1 The change in the optical axis deviation correction value Δx is the threshold value -α th From α th The change in the optical axis deviation correction value Δx is within the range of the threshold value -α th From α th The fact that the change amount Δx is within the range of the threshold α th This indicates that the threshold value is less than α. th and α th is preset in the determination unit 34.

[0024] When the amount of change Δx in the optical axis deviation correction value satisfies the condition of equation (2), the determination unit 34 extends the rewrite interval tw, which is the time interval for saving the optical axis deviation correction value in the memory 50, by an extension time n [min] as shown in equation (3), to set the extended rewrite interval tw'. This enables the determination unit 34 to reduce the frequency of rewriting the optical axis deviation correction value in the memory 50 compared to before the change. The extension time n is the amount of change in the rewrite interval tw. -α th <Δx<α th …(2) tw'=tw+n …(3)

[0025] 5 is a graph showing the transition of the optical axis deviation correction value when the amount of change in the optical axis deviation correction value is large, where the vertical axis represents the optical axis deviation correction value and the horizontal axis represents time.

[0026] time t n The optical axis deviation correction value at x(t n ) and time t n+1 The optical axis deviation correction value at x(t n+1), the change in the optical axis deviation correction value Δx is expressed as x(t n+1 ) and x(t n 3, the calculation unit 33 calculates the amount of change Δx in the optical axis deviation correction value using equation (1).

[0027] Fig. 6 is a graph showing the relationship between the amount of change in the optical axis deviation correction value and the threshold value in the case shown in Fig. 5. The vertical axis of Fig. 6 represents the amount of change in the optical axis deviation correction value, and the horizontal axis of Fig. 6 represents time.

[0028] In Figure 6, time t n+1 The change in the optical axis deviation correction value Δx is the threshold value -α th From α th This indicates that the change in the optical axis deviation correction value Δx is outside the range of the threshold value -α th From α th If the value is outside the range of the threshold value α, the condition of the formula (2) is not satisfied. th This indicates that the above is the case.

[0029] If the change amount Δx of the optical axis deviation correction value does not satisfy the condition of equation (2), the determination unit 34 shortens the rewrite interval tw by the shortening time m [min] as shown in equation (4) to set the shortened rewrite interval tw''. This enables the determination unit 34 to increase the frequency of rewriting the optical axis deviation correction value to the memory 50 compared to before the change. The shortening time m is the amount of change in the rewrite interval tw. tw''=tw+m …(4)

[0030] In this way, the determination unit 34 determines whether the magnitude of the change amount Δx in the optical axis deviation correction value is greater than or equal to the threshold value α th If the change amount Δx of the optical axis deviation correction value is less than the threshold value α, the rewrite interval tw is extended to reduce the frequency of rewriting the optical axis deviation correction value to the memory 50. th If this is the case, the rewrite interval tw is shortened to increase the frequency with which the optical axis deviation correction value is rewritten to the memory 50.

[0031] FIG. 7 is a flowchart illustrating the process of optimizing the rewrite frequency according to the first embodiment.

[0032] In step S1, the calculation processing unit 30 calculates the time t n The optical axis deviation correction value x(t n ) is stored in the data storage device 40.

[0033] In step S2, the calculation processing unit 30 calculates the time t n+1 The optical axis deviation correction value x(t n+1 ) is stored in the data storage device 40.

[0034] In step S3, the arithmetic processing unit 30 calculates the amount of change Δx in the stored optical axis deviation correction value.

[0035] In step S4, the calculation processing unit 30 determines whether the calculated change amount Δx of the optical axis deviation correction value is less than or equal to −α th <Δx<α th Determine whether the change Δx is -α th <Δx<α th If the change amount Δx is greater than or equal to the threshold value α th If the change amount Δx is less than −α th <Δx<α th does not satisfy the above condition, that is, when the magnitude of the change amount Δx is smaller than the threshold value α th If so, the processing unit 30 proceeds to step S6.

[0036] In step S5, the arithmetic processing unit 30 extends the rewrite interval tw.

[0037] In step S6, the arithmetic processing unit 30 shortens the rewrite interval tw.

[0038] In step S7, the arithmetic processing device 30 rewrites the optical axis deviation correction value in the memory 50 after the extended or shortened rewrite interval tw' or tw'' has elapsed. That is, after the extended or shortened rewrite interval tw' or tw'' has elapsed, the arithmetic processing device 30 saves the optical axis deviation correction value stored in the data storage device 40 in the memory 50. Thereafter, the arithmetic processing device 30 ends this process.

[0039] As described above, the vehicle electronic device 1 according to the first embodiment changes the rewrite frequency, which is the frequency at which correction values ​​for correcting the optical axis misalignment of the cameras 11 and 12 in the image data captured by the cameras 11 and 12 are stored in the memory 50, based on the amount of change in the correction values.

[0040] As a result, the vehicle electronic device 1 according to the first embodiment can reduce the rewrite frequency when, for example, the change in the optical axis deviation correction value is small, thereby reducing the number of times the memory 50 is rewritten. Therefore, the vehicle electronic device 1 according to the first embodiment can prevent the number of times the memory 50 is rewritten from exceeding the rewrite limit, thereby preventing the data retention reliability of the memory 50 from being impaired. At the same time, the vehicle electronic device 1 according to the first embodiment can increase the rewrite frequency when, for example, the change in the optical axis deviation correction value is large, thereby backing up the latest optical axis deviation correction value corresponding to the newest possible optical axis deviation. Therefore, the vehicle electronic device 1 according to the first embodiment can correct the optical axis deviation using the latest optical axis deviation correction value, thereby preventing deterioration of sensing accuracy due to correction of the optical axis deviation using an old optical axis deviation correction value. In this way, the vehicle electronic device 1 according to the first embodiment can optimize the rewrite frequency of the optical axis deviation correction value in the memory 50 according to the change in the optical axis deviation correction value. Therefore, according to the first embodiment, it is possible to provide the in-vehicle electronic device 1 capable of optimizing the frequency at which the correction value for correcting the optical axis deviation is rewritten in the memory 50.

[0041] Furthermore, the in-vehicle electronic device 1 according to the first embodiment includes cameras 11 and 12, and an image processing device 20 that processes image data captured by the cameras 11 and 12. The image processing device 20 includes a memory 50, an image data acquisition unit 31 that acquires image data from the cameras 11 and 12, a calibration unit 32 that performs calibration including calculation of an optical axis deviation correction value, a calculation unit 33 that calculates a change amount in the calculated optical axis deviation correction value, a determination unit 34 that determines a rewrite frequency based on the calculated change amount in the optical axis deviation correction value, and a control unit 35 that stores the optical axis deviation correction value in the memory 50 in accordance with the determined rewrite frequency.

[0042] As a result, the in-vehicle electronic device 1 according to the first embodiment can optimize the rewrite frequency by incorporating the calculation unit 33, the determination unit 34, and the control unit 35 into the image processing device 20 of an existing stereo camera device. Therefore, the in-vehicle electronic device 1 according to the first embodiment can easily optimize the rewrite frequency of the optical axis deviation correction value in the memory 50.

[0043] Furthermore, in the vehicle electronic device 1 according to the first embodiment, when the magnitude of the change in the optical axis deviation correction value is less than a threshold value, the decision unit 34 extends the rewrite interval, which is the time interval for saving the optical axis deviation correction value in the memory 50, to reduce the rewrite frequency, and when the magnitude of the change in the optical axis deviation correction value is equal to or greater than the threshold value, the decision unit 34 shortens the rewrite interval to increase the rewrite frequency.

[0044] As a result, the in-vehicle electronic device 1 according to the first embodiment can reliably ensure data retention reliability by reducing the number of times the memory 50 is rewritten, while backing up the latest optical axis deviation correction value and reliably suppressing deterioration of sensing accuracy. Therefore, the in-vehicle electronic device 1 according to the first embodiment can reliably optimize the frequency of rewriting the optical axis deviation correction value to the memory 50.

[0045] Furthermore, in the vehicle electronic device 1 according to the first embodiment, the memory 50 is a NAND-type nonvolatile memory.

[0046] That is, the in-vehicle electronic device 1 according to the first embodiment can employ, as the memory 50 for storing the optical axis deviation correction value, a NAND-type nonvolatile memory which is less expensive than a NOR-type memory but has a smaller limit on the number of times it can be rewritten. This makes it possible for the in-vehicle electronic device 1 according to the first embodiment to achieve cost reduction while optimizing the frequency at which the optical axis deviation correction value is rewritten to the memory 50.

[0047] Furthermore, in the in-vehicle electronic device 1 according to the first embodiment, the cameras 11 and 12 are a plurality of cameras provided in a stereo camera device.

[0048] As a result, the in-vehicle electronic device 1 according to the first embodiment can back up the latest optical axis deviation correction value corresponding to the latest optical axis deviation as much as possible in a stereo camera device in which optical axis deviation is more likely to directly lead to deterioration of sensing accuracy than in a monocular camera device. Therefore, the in-vehicle electronic device 1 according to the first embodiment can optimize the frequency of rewriting the optical axis deviation correction value to the memory 50 so as not to deteriorate the sensing accuracy in the stereo camera device.

[0049] [Example 2] Fig. 8 is a graph showing threshold values ​​set in the determination unit 34 according to the second embodiment. The vertical axis of Fig. 8 represents the amount of change in the optical axis deviation correction value, and the horizontal axis of Fig. 8 represents time.

[0050] The decision unit 34 according to the second embodiment has a threshold value α th ,-α th Not only the threshold β th ,-β th is set in advance. The threshold value β th is the threshold α th The threshold value β is set to a value greater than the threshold value β. th The condition for is expressed as in equation (5). -β th <Δx<β th …(5)

[0051] The determination unit 34 according to the second embodiment determines the rewrite interval tw based on the conditions of the formulas (2) and (5) as follows. If the condition of the formula (2) is satisfied, the determination unit 34 extends the rewrite interval tw by an extension time n [min], and sets the extended rewrite interval as tw'. If the condition of the formula (5) is not satisfied, the determination unit 34 shortens the rewrite interval tw by the shortening time m [min], and sets the shortened rewrite interval tw''. If the condition of the formula (2) is not satisfied and the condition of the formula (5) is satisfied, the determination unit 34 maintains the current rewrite interval tw.

[0052] The vehicle electronic device 1 according to the second embodiment can not only extend or shorten the rewrite interval but also maintain the current state, so that the rewrite frequency can not only be lowered or increased but also maintained as it is. Therefore, the vehicle electronic device 1 according to the second embodiment can optimize the rewrite frequency of the optical axis deviation correction value to the memory 50 with higher accuracy than the first embodiment.

[0053] [Example 3] Fig. 9 is a graph showing an extension time function set in the determination unit 34 according to the third embodiment. The vertical axis of Fig. 9 indicates the amount of change in the optical axis deviation correction value, and the horizontal axis of Fig. 9 indicates the extension time. Fig. 10 is a graph showing a reduction time function set in the determination unit 34 according to the third embodiment. The vertical axis of Fig. 10 indicates the amount of change in the optical axis deviation correction value, and the horizontal axis of Fig. 10 indicates the reduction time.

[0054] In the determination unit 34 according to the first embodiment, the extension time n and the reduction time m, which are the amounts of change in the rewriting interval tw, are constant values. In contrast to this, in the determination unit 34 according to the third embodiment, an extension time function f(Δx) as shown in FIG. 9 is defined for the extension time n, which is the amount of change in the rewriting interval tw. Similarly, in the determination unit 34 according to the third embodiment, reduction time functions f'(Δx) and f''(Δx), as shown in FIG. 10, are defined for the reduction time m, which is the amount of change in the rewriting interval tw. As a result, in the determination unit 34 according to the third embodiment, the extension time n and the reduction time m, which are the amounts of change in the rewriting interval tw, can be variable values.

[0055] When the condition of formula (2) is satisfied, the determination unit 34 according to the third embodiment calculates the extension time n by substituting the change amount Δx of the optical axis deviation correction value into the extension time function f(Δx) as shown in formula (6). Then, the determination unit 34 according to the third embodiment determines the extended rewriting interval tw′ from formula (3). n=f(Δx) …(6)

[0056] When the condition of formula (2) is not satisfied, the determination unit 34 according to the third embodiment calculates the shortened time m by substituting the change amount Δx of the optical axis deviation correction value into the shortened time functions f'(Δx) and f''(Δx) as shown in formulas (7) and (8). Then, the determination unit 34 according to the third embodiment determines the shortened rewriting interval tw'' from formula (4). m=f'(Δx) …(7) m=f''(Δx) …(8)

[0057] In this way, a function indicating the relationship between the change amount of the optical axis deviation correction value and the change amount of the rewriting interval is preset in the determination unit 34 according to the embodiment 3. The determination unit 34 according to the embodiment 3 determines the rewriting frequency by substituting the change amount of the optical axis deviation correction value calculated by the calculation unit 33 into the function and calculating the change amount of the rewriting interval.

[0058] As a result, the in-vehicle electronic device 1 according to the third embodiment can set the change amount of the rewrite interval to a variable value that varies according to the change amount of the optical axis deviation correction value, thereby enabling more appropriate optimization according to the change amount of the optical axis deviation correction value. Therefore, the in-vehicle electronic device 1 according to the third embodiment can optimize the rewrite frequency of the optical axis deviation correction value to the memory 50 with higher accuracy than that of the first embodiment.

[0059] [Example 4] Fig. 11 is a diagram showing the configuration of the vehicle electronic device 1 according to the fourth embodiment. Fig. 12 is a table illustrating the optimization of the rewrite frequency according to the fourth embodiment.

[0060] Due to the physical characteristics of the memory 50, data corruption and other problems are more likely to occur when data is rewritten at high temperatures than at room temperature, and data retention reliability is more likely to be impaired. Therefore, the in-vehicle electronic device 1 according to the fourth embodiment determines the rewrite frequency taking into account the temperature of the in-vehicle electronic device 1.

[0061] As shown in FIG. 11 , the vehicle electronic device 1 according to the fourth embodiment further includes a temperature sensor 60 for detecting the temperature of the vehicle electronic device 1. The temperature of the vehicle electronic device 1 detected by the temperature sensor 60 may be the temperature of the cameras 11 and 12, the temperature of the memory 50, or the ambient temperature thereof. The temperature sensor 60 is configured with various temperature sensors such as a thermistor. The temperature detected by the temperature sensor 60 is stored in the data storage device 40. The determination unit 34 according to the fourth embodiment determines the rewrite frequency based on the amount of change in the optical axis deviation correction value and the temperature of the vehicle electronic device 1. Specifically, the determination unit 34 according to the fourth embodiment sets the rewrite frequency when the temperature of the vehicle electronic device 1 is high lower than the rewrite frequency when the temperature of the vehicle electronic device 1 is normal temperature.

[0062] As a result, the vehicle electronic device 1 according to the fourth embodiment can reliably reduce the number of times the memory 50 is rewritten, thereby ensuring data retention reliability, at high temperatures where the data retention reliability of the memory 50 is likely to be impaired. At the same time, the vehicle electronic device 1 according to the fourth embodiment can back up the latest optical axis deviation correction value to suppress deterioration of sensing accuracy. Therefore, the vehicle electronic device 1 according to the fourth embodiment can optimize the frequency of rewriting the optical axis deviation correction value to the memory 50 with even greater accuracy than the first embodiment.

[0063] 12 shows how the rewriting interval tw is changed for each section of the temperature T of the vehicle electronic device 1 when the magnitude of the change amount Δx of the optical axis deviation correction value is small (for example, less than 1.0 pix), when it is large (for example, 1.0 pix or more and 2.0 pix or less), and when it is extremely large (for example, more than 2.0 pix). In FIG. 12, the boundary value (for example, 1.0 pix) that distinguishes between the cases where the magnitude of the change amount Δx of the optical axis deviation correction value is small and the case where it is large is the threshold value α th12, the boundary value (for example, 2.0 pix) that distinguishes between a case where the magnitude of the amount of change Δx in the optical axis deviation correction value is large and a case where the magnitude is extremely large may be a limit value of the magnitude of the amount of change Δx in the optical axis deviation correction value that corresponds to a limit value of the allowable sensing accuracy.

[0064] In Fig. 12, the change amount of the rewrite interval tw is expressed as one of "medium extension," "large extension," "extra large extension," "medium shortening," "small shortening," and "minimal shortening." For example, "large extension" means that the rewrite interval tw is extended and that the extension time, which is the amount of change in the rewrite interval tw, is large. For example, "minimal shortening" means that the rewrite interval tw is shortened and that the shortening time, which is the amount of change in the rewrite interval tw, is extremely small.

[0065] As shown in FIG. 12, the determination unit 34 according to the fourth embodiment determines whether the magnitude of the change amount Δx in the optical axis deviation correction value is a threshold value (α th ), the rewriting interval tw is extended, and the extension time, which is the amount of change in the rewriting interval tw when the temperature T of the vehicle electronic device 1 is high, is set to be longer than when the temperature T of the vehicle electronic device 1 is at room temperature, thereby reducing the rewriting frequency. th ) or more, the rewrite interval tw is shortened, and the shortened time, which is the change amount of the rewrite interval tw when the temperature T of the vehicle electronic device 1 is high, is made smaller than when the temperature T of the vehicle electronic device 1 is at room temperature, thereby increasing the rewrite frequency.

[0066] As a result, the vehicle electronic device 1 according to the fourth embodiment can determine the rewrite interval so as to ensure both the reliability of data retention and the suppression of deterioration in sensing accuracy, depending on the amount of change in the optical axis deviation correction value and the temperature of the vehicle electronic device 1. Therefore, the vehicle electronic device 1 according to the fourth embodiment can optimize the rewrite frequency more appropriately than the first embodiment. Therefore, the vehicle electronic device 1 according to the fourth embodiment can optimize the rewrite frequency of the optical axis deviation correction value to the memory 50 with more accuracy than the first embodiment.

[0067] Fig. 13 is a graph showing an extension time function set in the determination unit 34 according to the fourth embodiment. The vertical axis of Fig. 13 indicates the amount of change in the optical axis deviation correction value, and the horizontal axis of Fig. 13 indicates the extension time. Fig. 14 is a graph showing a reduction time function set in the determination unit 34 according to the fourth embodiment. The vertical axis of Fig. 14 indicates the amount of change in the optical axis deviation correction value, and the horizontal axis of Fig. 14 indicates the reduction time.

[0068] In FIG. 13, the extension time function f(Δx) is an example of an extension time function used in the case of "medium extension" shown in FIG. 12. The extension time function g(Δx) is an example of an extension time function used in the case of "large extension" shown in FIG. 12. The extension time function h(Δx) is an example of an extension time function used in the case of "extra large extension" shown in FIG. 12. In FIG. 14, the shortening time functions f'(Δx) and f''(Δx) are examples of shortening time functions used in the case of "medium shortening" shown in FIG. 12. The shortening time functions g'(Δx) and g''(Δx) are examples of shortening time functions used in the case of "small shortening" shown in FIG. 12. The shortening time functions h'(Δx) and h''(Δx) are examples of shortening time functions used in the case of "minimal shortening" shown in FIG. 12.

[0069] In the determination unit 34 according to the fourth embodiment, as in the third embodiment, an extension time function as shown in FIG. 13 and a shortening time function as shown in FIG. 14 may be defined for the extension time and shortening time, which are the amounts of change in the rewrite interval, respectively.

[0070] As a result, the vehicle electronic device 1 according to the fourth embodiment can set the extension time and shortening time, which are the amounts of change in the rewrite interval, to variable values ​​that vary depending on the amount of change in the optical axis deviation correction value and the temperature of the vehicle electronic device 1. Therefore, the vehicle electronic device 1 according to the fourth embodiment can more appropriately optimize the amount of change in the rewrite interval depending on the amount of change in the optical axis deviation correction value and the temperature of the vehicle electronic device 1. Therefore, the vehicle electronic device 1 according to the fourth embodiment can optimize the frequency of rewriting the optical axis deviation correction value to the memory 50 with higher accuracy than the first and third embodiments.

[0071] FIG. 15 is a flowchart illustrating a process of optimizing the rewrite frequency according to the fourth embodiment.

[0072] In step S11, the calculation processing unit 30 calculates the time t n The optical axis deviation correction value x(t n ) is stored in the data storage device 40.

[0073] In step S12, the calculation processing unit 30 calculates the time t n+1 The optical axis deviation correction value x(t n+1 ) is stored in the data storage device 40.

[0074] In step S13, the arithmetic processing unit 30 calculates the amount of change Δx in the stored optical axis deviation correction value.

[0075] In step S14, the calculation processing unit 30 calculates the time t n+1 The temperature T of the vehicle electronic device 1 at is stored in the data storage device 40.

[0076] In step S15, the calculation processing unit 30 determines whether the calculated change amount Δx of the optical axis deviation correction value is less than or equal to −α th <Δx<α th Determine whether the change Δx is -α th <Δx<α th If the change amount Δx is greater than or equal to the threshold value α th If the change amount Δx is less than -αth <Δx<α th does not satisfy the above condition, that is, when the magnitude of the change amount Δx is smaller than the threshold value α th If so, the arithmetic processing unit 30 proceeds to step S18.

[0077] In step S16, the processing unit 30 determines the extension time function to be used from the stored temperature T of the vehicle electronic device 1.

[0078] In step S17, the calculation processing unit 30 extends the rewriting interval tw in accordance with the determined extension time function.

[0079] In step S18, the processing unit 30 determines the shortened time function to be used from the stored temperature T of the vehicle electronic device 1.

[0080] In step S19, the calculation processing unit 30 shortens the rewriting interval tw in accordance with the determined shortening time function.

[0081] In step S20, the arithmetic processing device 30 rewrites the memory 50 when the extended or shortened rewrite interval tw' or tw'' has elapsed. That is, when the extended or shortened rewrite interval tw' or tw'' has elapsed, the arithmetic processing device 30 saves the optical axis deviation correction value stored in the data storage device 40 in the memory 50. Thereafter, the arithmetic processing device 30 ends this process.

[0082] [Example 5] Fig. 16 is a graph showing an extension time function set in the determination unit 34 according to the fifth embodiment. The vertical axis of Fig. 16 indicates the amount of change in the optical axis deviation correction value, and the horizontal axis of Fig. 16 indicates the extension time. Fig. 17 is a graph showing a reduction time function set in the determination unit 34 according to the fifth embodiment. The vertical axis of Fig. 17 indicates the amount of change in the optical axis deviation correction value, and the horizontal axis of Fig. 17 indicates the reduction time.

[0083] In FIG. 16, the extension time function f(Δx) is set when the number of times the memory 50 is rewritten is a predetermined value γ thThe extension time function j(Δx) is used when the number of times the memory 50 is rewritten is equal to or less than a predetermined value γ th 17, the shortening time functions f′(Δx) and f″(Δx) are used when the number of times the memory 50 is rewritten exceeds a predetermined value γ th The time-saving functions j'(Δx) and j''(Δx) are used when the number of times the memory 50 is rewritten is equal to or less than a predetermined value γ th is an example of a shortened time function used when

[0084] The determination unit 34 according to the fifth embodiment determines whether the number of times the memory 50 is rewritten is a predetermined value γ th If this number is exceeded, the number of times the memory 50 is rewritten can be reduced by the following method. The optical axis deviation correction value is not rewritten (saved) to memory 50. Only the rewrite interval tw is extended, and the rewrite interval tw is not shortened. The extension time function f(Δx) and the shortened time functions f'(Δx) and f''(Δx) set in the determination unit 34 according to the third embodiment are changed to the extension time function j(Δx) and the shortened time functions j'(Δx) and j''(Δx) shown in FIGS. 16 and 17.

[0085] As a result, the vehicle electronic device 1 according to the fifth embodiment can further reduce the number of times the memory 50 is rewritten compared to the third embodiment, thereby further ensuring data retention reliability. At the same time, the vehicle electronic device 1 according to the fifth embodiment can back up the latest optical axis deviation correction value to suppress deterioration of sensing accuracy. Therefore, the vehicle electronic device 1 according to the fifth embodiment can optimize the frequency of rewriting the optical axis deviation correction value to the memory 50 with even higher accuracy than the third embodiment.

[0086] [Other Examples] Although the vehicle electronic device 1 according to the first to third embodiments extends and shortens the rewrite interval, the vehicle electronic device 1 may only extend the rewrite interval without shortening it. Also, the vehicle electronic device 1 may set at least one of a lower limit and an upper limit to the rewrite interval, and change the frequency of rewriting the optical axis deviation correction value to the memory 50 within a predetermined range.

[0087] Furthermore, the vehicle electronic device 1 may rewrite the memory 50 (save the optical axis deviation correction value in the memory 50) during at least one of the periods when the vehicle speed of the vehicle equipped with the vehicle electronic device 1 is zero [km / h] and when the ignition of the vehicle is off. Because the processing load of the arithmetic processing device 30 is large while the vehicle is traveling, rewriting the memory 50 while the vehicle is traveling increases the amount of heat generated by the arithmetic processing device 30, which may adversely affect the data retention reliability and sensing accuracy of the memory 50. Therefore, the vehicle electronic device 1 rewrites the memory 50 while the vehicle is stopped, when the processing load of the arithmetic processing device 30 is small, thereby suppressing an increase in the amount of heat generated by the arithmetic processing device 30 and thereby suppressing adverse effects on the data retention reliability and sensing accuracy of the memory 50.

[0088] Furthermore, the vehicle electronic device 1 is configured such that the number of times the memory 50 is rewritten exceeds a predetermined value γ th If the value exceeds the threshold, the storage area for the optical axis deviation correction value may be changed to another storage area within the memory 50 or to another storage area outside the memory 50. This may reduce the number of times the memory 50 is rewritten by the in-vehicle electronic device 1.

[0089] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0090] Furthermore, the above-described configurations, functions, processing units, processing means, etc. may be partially or entirely realized by hardware, for example, by designing them as integrated circuits. The above-described configurations, functions, etc. may also be realized by software, in which a processor interprets and executes a program that realizes each function. Information such as the program, tape, and file that realizes each function can be stored in a memory, a recording device such as a hard disk or solid state drive (SSD), or a recording medium such as an IC card, SD card, or DVD.

[0091] In addition, the control lines and information lines shown are those that are considered necessary for the explanation, and do not necessarily show all the control lines and information lines in the product. In reality, it can be assumed that almost all components are interconnected. [Explanation of symbols]

[0092] 1... Vehicle electronic device, 11, 12... Camera, 20... Image processing device, 31... Image data acquisition unit, 32... Calibration unit, 33... Calculation unit, 34... Determination unit, 35... Control unit, 50... Memory, 60... Temperature sensor

Claims

1. A rewrite frequency, which is the frequency at which a correction value for correcting the optical axis deviation of the camera in image data captured by the camera is stored in a memory, is changed based on the amount of change in the correction value.

1. A vehicle electronic device comprising:

2. The camera; an image processing device that processes the image data captured by the camera, The image processing device includes: the memory; an image data acquisition unit that acquires the image data from the camera; a calibration unit that performs calibration including calculation of the correction value; a calculation unit that calculates the amount of change in the calculated correction value; a determination unit that determines the rewriting frequency based on the calculated change amount of the correction value; a control unit that stores the correction value in the memory in accordance with the determined rewriting frequency; 2. The vehicle electronic device according to claim 1.

3. The determination unit When the magnitude of the change amount of the correction value is less than a threshold value, a rewrite interval, which is a time interval for saving the correction value in the memory, is extended to reduce the rewrite frequency; If the magnitude of the change amount of the correction value is equal to or greater than the threshold value, the rewrite interval is shortened to increase the rewrite frequency.

3. The vehicle electronic device according to claim 2.

4. a function indicating a relationship between a change amount of a rewrite interval, which is a time interval at which the correction value is stored in the memory, and the change amount of the correction value, is set in advance in the determination unit; The determination unit determines the rewrite frequency by substituting the calculated change amount of the correction value into the function to calculate the change amount of the rewrite interval.

3. The vehicle electronic device according to claim 2.

5. a temperature sensor for detecting a temperature of the vehicle electronic device; The determination unit sets the rewrite frequency when the temperature is high to be lower than the rewrite frequency when the temperature is normal temperature.

3. The vehicle electronic device according to claim 2.

6. The determination unit When the magnitude of the change amount of the correction value is less than a threshold value, a rewrite interval, which is a time interval for saving the correction value in the memory, is extended, and the change amount of the rewrite interval at the high temperature is made larger than that at the normal temperature, thereby reducing the rewrite frequency; When the magnitude of the change amount of the correction value is equal to or greater than the threshold value, the rewrite interval is shortened, and the change amount of the rewrite interval at the high temperature is made smaller than that at the normal temperature, thereby increasing the rewrite frequency.

6. The vehicle electronic device according to claim 5.

7. The memory is a NAND type nonvolatile memory.

2. The vehicle electronic device according to claim 1.

8. The camera is a plurality of cameras provided in a stereo camera device.

2. The vehicle electronic device according to claim 1.

Images