JP6023030B2 - Rudder angle correction method, rudder angle correction device, imaging device, and rudder angle correction system - Google Patents

Description

  The present invention relates to a steering angle correction method, a steering angle correction device, an imaging device, and a steering angle correction system for correcting a steering angle of a moving body.

  2. Description of the Related Art Conventionally, a technique is known in which an in-vehicle camera is installed on a moving body such as an automobile, and an image serving as an index for supporting driving is superimposed on a captured peripheral image of the moving body. In order to superimpose such an index on the peripheral image, a steering angle detected by a steering angle sensor or the like is used. Since the detected steering angle may deviate from the actual steering angle due to use over time, steering replacement, or the like, neutral point correction of the steering angle is performed (for example, Patent Document 1).

Japanese Patent No. 4323402

  However, in the prior art, it is necessary to accurately operate the steering to the maximum steering angle or the minimum steering angle in order to correct the steering angle. Thus, a special process is required for the neutral point correction of the steering angle, and the operation is complicated.

  An object of the present invention made in view of such circumstances is to provide a rudder angle correction method, a rudder angle correction device, an imaging device, and a rudder angle correction system that can correct the rudder angle by reducing the complexity of operation. is there.

In order to solve the above problem, the rudder angle correction method according to the present invention,
Obtaining a set of images obtained by simultaneously imaging the left and right steered wheels and the steering angle of the moving body at the time of capturing the set of images in association with each other;
Calculating the degree of symmetry of the left and right steered wheels on the set of images;
Calculating a correction value for correcting the steering angle based on the degree of symmetry.

Further, the rudder angle correction method according to the present invention includes:
Acquiring the set of images at different steering angles;
In the step of calculating the correction value, the correction value is preferably calculated based on the distribution of the symmetry with respect to the steering angle.

Further, the rudder angle correction method according to the present invention includes:
Extracting the left and right steered wheels on the set of images by ellipse detection;
In the step of calculating the degree of symmetry, it is preferable to calculate the degree of symmetry using a parameter of an ellipse to be detected.

Further, the rudder angle correction method according to the present invention includes:
In the step of calculating the degree of symmetry, it is preferable to calculate the degree of symmetry by assigning more weight to the parameter indicating at least one of the short side and the inclination of the ellipse than the other parameters.

Further, the rudder angle correction method according to the present invention includes:
In the step of calculating the degree of symmetry, the degree of symmetry is preferably calculated using a degree of correlation based on image matching based on the set of images.

In addition, the rudder angle correction device according to the present invention,
An acquisition unit that acquires a set of images obtained by simultaneously imaging the left and right steering wheels, and a steering angle of a moving body when the set of images is captured;
And an arithmetic unit that calculates a correction value for correcting the steering angle based on the symmetry of the left and right steering wheels on the set of images.

In addition, an imaging apparatus according to the present invention includes:
An acquisition unit that acquires a set of images obtained by simultaneously imaging the left and right steering wheels and a steering angle of the moving body at the time of imaging the set of images, and the left and right steering on the set of images A rudder angle correction device comprising a calculation unit that calculates a correction value for correcting the rudder angle based on the degree of symmetry of the wheel;
A first imaging unit that generates the set of images;
A second imaging unit that generates a peripheral image obtained by imaging a peripheral region of the moving body;
An image superimposing unit that superimposes an index on the peripheral image based on the correction value is provided.

Further, the rudder angle correction system according to the present invention,
A first imaging unit that generates a set of images obtained by simultaneously imaging the left and right steering wheels;
An acquisition unit that associates and acquires the set of images and the steering angle of the moving body at the time of capturing the set of images;
An arithmetic unit that calculates a correction value for correcting the steering angle based on the symmetry of the left and right steering wheels on the set of images;
A second imaging unit that generates a peripheral image obtained by imaging a peripheral region of the moving body;
An image superimposing unit that superimposes an index on the peripheral image based on the correction value;
And a display unit that displays a peripheral image on which the index is superimposed.

  According to the rudder angle correction method, the rudder angle correction device, the imaging device, and the rudder angle correction system according to the present invention, it becomes possible to correct the rudder angle while reducing the complexity of the operation.

It is the schematic which shows arrangement | positioning of the component of the steering angle correction system which concerns on the 1st Embodiment of this invention. It is a functional block diagram which shows schematic structure of the steering angle correction system which concerns on the 1st Embodiment of this invention. It is a figure which shows the example of the captured image of the right side camera of FIG. It is a figure which shows the example of the captured image of the left side camera of FIG. It is a figure which shows the example of the image displayed on the display part of FIG. It is a figure which shows the example which performed the ellipse detection with respect to the captured image of the side camera of FIG. It is a figure which shows the probability distribution of the symmetry degree which concerns on the 1st Embodiment of this invention. It is a flowchart explaining operation | movement of the steering angle correction system which concerns on the 1st Embodiment of this invention. It is a figure which shows the probability distribution of the symmetry degree which concerns on the 2nd Embodiment of this invention. It is a flowchart explaining operation | movement of the rudder angle correction | amendment system by the modification of this invention.

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

(First embodiment)
First, the steering angle correction system according to the first embodiment of the present invention will be described. FIG. 1 is a schematic diagram illustrating an arrangement of components of a steering angle correction system A according to the first embodiment on a moving body 10. The moving body 10 is a vehicle, for example.

  The two side cameras 11 of the steering angle correction system A are, for example, 45 ° from the center of the side surface of the steering wheel 15 toward the rear of the moving body 10 when viewed from the side of the moving body 10 with respect to the vertically upward direction (FIG. 1). (See (b)), the mobile body 10 is arranged symmetrically at a position of 15 ° toward the left and right outer sides of the mobile body 10 when viewed from the rear (see FIG. 1C). Further, the two side cameras 11 are respectively disposed on the left and right side mirrors 16, for example. The left and right side cameras 11 can respectively image a peripheral area of the moving body 10 including one of the left and right steering wheels 15 of the moving body 10. The rear camera 12 of the steering angle correction system A is arranged so as to be able to image the rear peripheral region of the moving body 10. The steering angle correction device 13 of the steering angle correction system A is disposed at an arbitrary position of the moving body 10. The display unit 14 of the steering angle correction system A is disposed at a position that can be viewed from the driver's seat, and displays images output from the side camera 11 and the rear camera 12.

  Next, the configuration and function of the steering angle correction system A will be described in detail with reference to FIG. As shown in FIG. 2, the steering angle correction system A includes a side camera 11, a rear camera 12, a steering angle correction device 13, and a display unit 14.

  The side camera 11 includes an optical system 17, a side camera imaging unit (first imaging unit) 18, a steering angle determination unit 19, and a side camera control unit 20.

  The optical system 17 includes a plurality of lenses and forms a subject image.

The side camera imaging unit 18 is, for example, a CMOS imaging device, and generates an image obtained by imaging a subject image formed by the optical system 17. As described above, the left and right side cameras 11 are arranged so as to be able to image the peripheral area of the moving body 10 including one of the left and right steering wheels 15, and the generated images have various steering wheel steering angles. may include an image of the steering wheel 15 is theta _R. Here, the steered wheel steering angle θ _R is a turning angle of the steered wheel 15 where the steering angle neutral point in the steerable range of the steered wheel 15 is 0 °. In the present embodiment, the steering wheel steering angle theta _R is increased by the right rotation of the steering. The steered wheel steering angle θR becomes a positive value when the steering wheel rotates in the right direction from the steering angle neutral point, and becomes a negative value when the steering wheel rotates in the left direction from the steering angle neutral point.

Here, an image generated by the side camera 11 will be described. Steering wheel on the image 15, different shapes by the steering wheel steering angle theta _R. 3 shows examples of images generated by the right side camera 11 at different steering wheel steering angles θ _R , FIG. 3A shows θ _R = 0 °, FIG. 3B shows θ _R = 10 °, 3 (c) is θ _R = 20 °, FIG. 3 (d) is θ _R = 30 °, and FIG. 3 (e) is θ _R = −30 °. The side surface of the steered wheel 15 on the image has an elliptical shape at the steering angle neutral point (θ _R = 0 °) of the steered wheel 15 (see FIG. 3A). When the steered wheel steering angle θ _R increases from 0 °, a part of the side surface of the steered wheel 15 is hidden by the shadow of the moving body 10 and a part of the ellipse is missing (FIGS. 3B to 3D). reference). On the other hand, the steering wheel steering angle theta _R decreases from 0 °, the side surface of the steering wheel 15 below a certain steering angle is not reflected to a on the image (see FIG. 3 (e)).

Similarly steered wheels 15 on the image generated by the left side camera 11, different shapes by the steering wheel steering angle theta _R. FIG. 4 shows an example of an image generated by the right side camera 11 at different steering wheel steering angles θ _R , FIG. 4A shows θ _R = 0 °, FIG. 4B shows θ _R = −30 °, FIG. 4C shows θ _R = 30 °. The steering wheel steering angle theta _R decreases from 0 °, a portion of the side surface of the steering wheel 15 hidden behind the moving body 10, part of an ellipse is missing shape (see Figure 4 (b)). On the other hand, the steering wheel steering angle theta _R increases from 0 °, the side surface of the steering wheel 15 at a certain steering angle or more is not reflected to a on the image (see FIG. 4 (c)). When the steering wheel steering angle θ _R = 0 °, the steering wheels 15 on the images generated by the left and right side cameras 11 are symmetric (see FIGS. 3A and 4A).

The steering angle determination unit 19 (see FIG. 2) obtains the steering angle θ _m detected by the steering angle sensor during imaging by the side camera imaging unit 18 via the in-vehicle network 100 such as CAN, for example. The steering angle θ _m is a steering angle at which the steering angle neutral point in the steering possible range is 0 °. In the present embodiment, the steering angle θ _m detected by the steering angle sensor is increased by the clockwise rotation of the steering. In general, the steering angle θ _m and the steering wheel angle θ _R detected by the steering angle sensor have a one-to-one correspondence.

  The side camera control unit 20 controls the operation of each part of the side camera 11. For example, the side camera control unit 20 causes each side camera imaging unit 18 of the left and right side cameras 11 to generate a set of images obtained by imaging the left and right steering wheels 15 at 30 fps periodically. The side camera control unit 20 transmits and receives information via the in-vehicle network 100.

  The rear camera 12 includes an optical system 21, a rear camera imaging unit (second imaging unit) 22, a rear camera storage unit 23, an image superimposing unit 24, and a rear camera control unit 25.

  Similar to the optical system 17 of the side camera 11, the optical system 21 includes a plurality of lenses and forms a subject image.

  Similar to the side camera imaging unit 18, the rear camera imaging unit 22 captures a peripheral image formed by the optical system 21.

Rear camera storage unit 23 stores the correction value theta _a to obtain the steering angle correction device 13. It will be described in detail later correction value theta _a.

The image superimposing unit 24 acquires the steering angle θ _m detected by the steering angle sensor via the in-vehicle network 100. Further, the image superimposing unit 24 superimposes an index for driving assistance on a predetermined position on the peripheral image captured by the rear camera imaging unit 22 by using the steering angle θ _m detected by the steering angle sensor. Preferably, the image superimposing unit 24 uses the steering angle theta _m the steering angle sensor rear camera storage unit 23 is corrected by the correction value theta _a to be stored is detected, it superimposes an indicator for the driving support.

  The indicator 30 for driving assistance is, for example, a vehicle width extension line 31 and a distance guide line 32 as shown in FIG. The vehicle width extension line 31 is a trajectory passing through both ends of the moving body 10 during reverse travel, and the shape and the display position differ depending on the steering angle of the steering. The distance reference line 32 indicates a predetermined distance from the current moving body 10, for example, a distance of 1 m and 3 m. The driver can recognize the predicted traveling direction when the mobile object 10 moves backward by the index 30.

The rear camera control unit 25 (see FIG. 2) controls the operation of each part of the rear camera 12. For example, the rear camera control unit 25, is stored in the rear camera storage unit 23 receives the correction value theta _a from the steering angle correction device 13. The rear camera control unit 25 transmits and receives information via the in-vehicle network 100.

The steering angle correction device 13 calculates _a correction value θ _a for correcting the steering angle θ _m detected by the steering angle sensor so as to coincide with the actual steering angle θ _t of the steering. It will be described in detail later calculation of the correction value theta _a. The steering angle correction device 13 includes an acquisition unit 26, a correction device storage unit 27, an extraction unit 28, and a calculation unit 29.

For example, the acquisition unit 26 obtains a set of images obtained by simultaneously imaging the left and right steering wheels 15 from the left and right side cameras 11 via the in-vehicle network 100 and the steering angle θ _m detected by the steering angle sensor at the time of imaging. Acquired in association.

The correction device storage unit 27 stores the symmetry of the left and right steering wheels 15 on the set of images calculated by the calculation unit 29 in association with the steering angle θ _m detected by the steering angle sensor at the time of image capturing. Details of the degree of symmetry will be described later. The correction device storage unit 27 stores the correction value theta _a to the arithmetic unit 29 calculates.

  The extraction unit 28 extracts the steering wheel 15 on the set of images acquired by the acquisition unit 26. For example, the extraction unit 28 extracts the steering wheel 15 on the image by edge detection and ellipse detection (approximation). For edge detection, for example, an edge part on an image is detected using a canny filter. For ellipse detection, for example, Hough transform is used to calculate an ellipse shape approximating the steered wheel 15 and its ellipse parameters. The ellipse parameters are the center coordinates (x, y) of the ellipse, the length a of the long side, the length b of the short side, and the inclination φ formed by the horizontal axis on the image and the long axis of the ellipse.

  Preferably, the extraction unit 28 extracts the steering wheel 15 on the image in a predetermined region on the image where the steering wheel 15 can be included. The predetermined area on the image in which the steering wheel 15 can be included may be determined in advance in consideration of, for example, variations in the mounting angle of the side camera 11, or may be automatically determined by the extraction unit 28 by an arbitrary method. .

Here, an ellipse detected by ellipse detection will be described. FIG. 6 shows an example of an ellipse (thick line in FIG. 6) detected for images generated by the right side camera 11 at different steering wheel steering angles θ _R , and FIG. 6A shows θ _R = 0 ° and FIG. ) Is θ _R = 10 °, FIG. 6C is θ _R = 20 °, and FIG. 6D is θ _R = 30 °. Further, FIG. 6 shows an example in which ellipse detection is performed on the wheel portion of the steered wheel 15, but for example, ellipse detection may be performed on the tire portion of the steered wheel 15. The θ example _R is not less than 10 °, but the wheel portion of the steering wheel 15 is a shape with the cut part of an ellipse (FIG. 3 (b) - (d) refer), the wheel of the steering wheel 15 by the elliptical detection An ellipse that fits the part is detected (see FIGS. 6B to 6D).

Oval to be detected, a different shape by the steering wheel steering angle theta _R at the time of imaging. In particular, the ellipse is detected, the steering wheel steering angle theta _R increases from 0 °, the inclination φ decreases formed by the long axis of the horizontal axis and the ellipse on the image, the short side length b is increased To do. On the other hand, even if the steering wheel steering angle theta _R is increased, the other ellipse parameter, i.e. the center coordinates (x, y) and the change in length a of the long side is relatively small (see FIG. 6). Similarly, the ellipse detected for images generated by the left side camera 11 at different steering wheel steering angles θ _R is similar to the horizontal axis on the image and the major axis of the ellipse when the steering wheel steering angle θ _R decreases from 0 °. Is reduced, and the length b of the short side is increased.

The computing unit 29 (see FIG. 2) calculates the degree of symmetry of the left and right steered wheels 15 on a set of images. The degree of symmetry is an index indicating the degree of left-right symmetry of the shape of the left and right steering wheels 15 on a set of images. For example, in the present embodiment, the degree of symmetry is the degree of correlation of image matching. The computing unit 29 performs image matching by horizontally inverting one of the set of elliptic images detected by the extracting unit 28, and calculates the degree of correlation of image matching as the degree of symmetry. Further, the calculation unit 29 associates the calculated degree of symmetry (correlation degree) with the steering rudder angle θ _m detected by the rudder angle sensor at the time of capturing a set of images used to calculate the degree of symmetry. The data is stored in the correction device storage unit 27.

Further, the calculation unit 29 calculates a probability distribution of symmetry (correlation degree) with respect to the steering angle θ _m detected by the steering angle sensor based on a plurality of data stored in the correction device storage unit 27 (FIG. 7). reference). Any probability distribution model can be used for the probability distribution. Further, the calculation unit 29 calculates the steering angle θ _p at the peak position of the calculated probability distribution. Preferably, the calculation unit 29 calculates the steering angle θ _p at the peak position of the probability distribution when data sufficient to calculate the probability distribution is accumulated. For example, the arithmetic unit 29 determines the peak position of the probability distribution when the number of accumulated data is equal to or greater than the predetermined threshold th ₁ and the calculated variance σ ² of the probability distribution is less than the predetermined threshold th _2. it may be configured to calculate the steering angle theta _p in.

Here, the steering angle θ _{p at} the peak position of the probability distribution calculated by the calculation unit 29 is estimated as the steering angle θ _m detected by the steering angle sensor when the actual steering angle θ _t of the steering is 0 °. Is done. When there is a deviation (hereinafter referred to as detection deviation) between the steering angle θ _m detected by the steering angle sensor and the actual steering angle θ _t of the steering, the actual steering angle θ _t of the steering is 0 °. The steering angle θ _m detected by the rudder angle sensor is equal to the detection deviation of the rudder angle sensor. Computing section 29 determines the steering angle theta _p at the peak position of the probability distribution as a detection deviation Δθ of the steering angle sensor.

When the absolute value of the determined detection deviation Δθ is equal to or greater than the predetermined threshold th ₃ , that is, the arithmetic unit 29, that is, the deviation between the steering angle θ _m detected by the steering angle sensor and the actual steering angle θ _t of the steering is detected. big time, is stored in the correction device the storage unit 27 the detected deviation Δθ as a correction value theta _a. Alternatively, the arithmetic unit 29, when the correcting device storage unit 27 has already stored the correction values theta _a is the absolute value of a value obtained by subtracting the correction value theta _a from detecting deviation Δθ predetermined threshold th ₃ or more At some time, the detection deviation Δθ is updated as _a new correction value θa and is stored in the correction device storage unit 27. Calculating section 29, via the in-vehicle network 100, and transmits the correction value theta _a to other components.

  Next, correction value calculation processing executed by the steering angle correction system A according to the first embodiment will be described with reference to the flowchart of FIG. This process is executed, for example, when the moving body 10 starts traveling.

  First, the side camera imaging unit 18 of the left and right side cameras 11 generates a set of images obtained by simultaneously imaging the peripheral area of the moving body 10 including one of the left and right steering wheels 15 (step S100).

Next, the steering angle determination unit 19, via the in-vehicle network 100, the steering angle sensor acquires a steering angle theta _m detected at the same time as the imaging of a set of images in step S100 (step S101).

Next, the acquisition unit 26 of the steering angle correction device 13 acquires the set of images in step S100 and the steering angle θ _m detected by the steering angle sensor in step S101 in association with each other via the in-vehicle network 100, for example. (Step S102).

  Next, the extraction unit 28 performs edge detection on the set of images in step S102 (step S103).

  Subsequently, the extraction unit 28 performs ellipse detection on the set of images subjected to edge detection in step S103 (step S104).

  Next, the computing unit 29 calculates the degree of symmetry of the left and right steered wheels 15 on the set of images in step S102 (step S105). For example, the calculating unit 29 performs image matching by horizontally inverting one of the pair of images subjected to ellipse detection in step S104, and calculates the degree of correlation of image matching as the degree of symmetry.

Subsequently, the calculation unit 29 stores data in which the degree of symmetry calculated in step S105 and the steering angle θ _m detected by the steering angle sensor acquired in step S102 are associated with each other in the correction device storage unit 27 ( Step S106).

Subsequently, the calculation unit 29 calculates a probability distribution of symmetry (correlation degree) with respect to the steering angle θ _m detected by the steering angle sensor, based on the data stored in the correction device storage unit 27 in step S106 ( Step S107).

Subsequently, the arithmetic unit 29 determines whether or not sufficient data has been accumulated to calculate the probability distribution (step S108). For example, the calculation unit 29 has the number of data stored in the correction device storage unit 27 equal to or greater than a predetermined threshold th ₁ and the variance σ ^{2 of the} probability distribution calculated in step S107 is less than the predetermined threshold th ₂ When it is, it is determined that sufficient data has been accumulated. When sufficient data is accumulated (step S108-Yes), the process proceeds to step S109. On the other hand, when sufficient data has not been accumulated (No in step S108), the process returns to step S100 to repeat the process and accumulate data.

In step S108, when enough data has been accumulated (step S108-Yes), the arithmetic unit 29 calculates the steering angle theta _p at the peak position of the probability distribution calculated in step S107 (step S109).

Subsequently, the arithmetic unit 29 determines the steering angle theta _p at the peak position of the probability distribution calculated in step S109 as detected deviation [Delta] [theta]. Further, the calculation unit 29 determines whether or not the absolute value of the detection deviation Δθ is greater than or equal to a predetermined threshold th ₃ (step S110). When the absolute value of the detected deviation Δθ is the threshold value th ₃ or more (step S110-Yes), the process proceeds to step S111. On the other hand, when the absolute value of the detected displacement Δθ is smaller than the threshold th ₃ (step S110-No), the process ends.

In step S110, when the absolute value of the detected deviation Δθ is the threshold value th ₃ or more (step S110-Yes), the arithmetic unit 29, is stored in the correction device the storage unit 27 the detected deviation Δθ as a correction value theta _a (step S111 ).

Thus, according to the steering angle correction system of the first embodiment, each right and left steered wheels 15 simultaneously based on the symmetry of the set of images captured, the correction value is calculated theta _a. Thus, for example, correction of the steering angle theta _m which the steering angle sensor during the travel of the moving body 10 is detected can be performed automatically, thereby reducing the complexity of the operation by the operator. Further, for example, information in the initial state before the measurement deviation Δθ occurs in the rudder angle sensor, such as the initial state, is not required, so that the correction can be performed regardless of the time when the rudder angle correction system is mounted on the moving body 10.

Further, according to the steering angle correction system of the first embodiment, for calculating the correction value theta _a based on the probability distribution of the symmetry with respect to the steering angle theta _m which the steering angle sensor detects the actual rudder steering The steering angle θ _m detected by the steering angle sensor when the angle θ _t is 0 ° can be estimated with high accuracy, and the calculation accuracy of the correction value θ _a can be improved. Further, to reduce the influence of the measurement error of the steering angle theta _m which the steering angle sensor detects, it can improve the calculation accuracy of the correction value theta _a.

Further, according to the steering angle correction system of the first embodiment, when sufficient data is stored to calculate the probability distribution of symmetry with respect to the steering angle θ _m detected by the steering angle sensor, the probability distribution The steering angle θ _p at the peak position is calculated, and the correction value θ _a is calculated using θ _p . Thus, for example, when the case and distributed the number of data is small is large, etc., to suppress the calculation and update of the correction value theta _a to if not correctly detect the peak, it is possible to improve the stability of the correction value theta _a.

Further, according to the steering angle correction system of the first embodiment, the absolute value of the deviation (detection deviation) Δθ between the steering angle θ _m detected by the steering angle sensor and the actual steering angle θ _t of the steering is obtained. When the threshold is th ₃ or more, the detection deviation Δθ is stored as _a correction value θa. Therefore, to suppress the calculation and update of the correction value theta _a by slight shift caused by the influence of the measurement error of the steering angle theta _m which the steering angle sensor detects, it can improve the calculation accuracy of the correction value theta _a.

  Further, according to the rudder angle correction system of the first embodiment, edge detection is performed on a set of images, and therefore, for example, due to changes in the environment such as weather and outside brightness while the mobile body 10 is traveling. The influence on the measurement image can be reduced, and the calculation accuracy of the correlation degree by image matching can be improved.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. The configuration of the steering angle correction system A according to the second embodiment is the same as that of the first embodiment, but the processing performed by the steering angle correction device 13 is different.

  The steering angle correction device 13 according to the second embodiment includes an acquisition unit 26, a correction device storage unit 27, an extraction unit 28, and a calculation unit 29, as in the first embodiment. Since the acquisition unit 26 and the correction device storage unit 27 are the same as those in the first embodiment, description thereof is omitted.

  Similar to the first embodiment, the extraction unit 28 extracts the steered wheels 15 on a set of images and calculates an elliptic parameter. The extraction unit 28 according to the second embodiment inverts one of the pair of images left and right, extracts the steering wheel 15 on both images, and calculates the ellipse parameters.

  The computing unit 29 calculates the symmetry degree of the left and right steered wheels 15 on a set of images, as in the first embodiment. Here, the calculation unit 29 according to the second embodiment calculates the degree of symmetry using the ellipse parameter calculated by the extraction unit 28 through ellipse detection. Specifically, the calculation unit 29 calculates a point α on the five-dimensional parameter space determined by the elliptic parameter of the steered wheel 15 detected from one of the images reversed left and right by the extraction unit 28. Similarly, the calculation unit 29 calculates a point β on the five-dimensional parameter space determined by the elliptic parameter of the steering wheel 15 detected from the other image. The distance d between two points on the parameter space is calculated by d = | α−β |. Here, when the correlation between the ellipse shapes detected from both images is high, the ellipse parameters are close to each other, and therefore the distance d is a small value. On the other hand, when the correlation between the two ellipse shapes is small, the ellipse parameters have different values, and thus the distance d is a large value. The calculation unit 29 calculates the distance d on the parameter space calculated using the ellipse parameter as the degree of symmetry. At this time, generally, the smaller the value of the distance d, the higher the symmetry.

Preferably, the calculation unit 29 calculates the degree of symmetry using a value obtained by weighting a plurality of ellipse parameters. As described above, the detected ellipse has a different shape depending on the steering wheel steering angle θ _R (see FIG. 6). Here, with respect to change in the steering wheel steering angle theta _R, the amount of change in the length b of the ellipse inclination φ and short large, other ellipse parameters, that is, the length of the center coordinates and the long side is small variation . That is, the length b of the ellipse inclination φ and short is sensitive to changes in the steering wheel steering angle theta _R. For example, at least one of the inclination φ and the short side length b among the ellipse parameters is weighted more than the other parameters, that is, the coordinates (x, y) and the long side length a, and points on the parameter space a and b are determined, and the distance d between the two points is calculated as the symmetry.

Similarly to the first embodiment, the calculation unit 29 calculates a probability distribution of symmetry (distance d), and calculates the correction value θ _a based on the steering angle θ _p at the peak position of the calculated probability distribution. calculate. In this embodiment, since the distance d on the parameter space calculated using the ellipse parameter is used as the degree of symmetry, the peak of the probability distribution appears downward (see FIG. 9).

Thus, according to the steering angle correction system of the second embodiment, the distance d on the parameter space calculated based on the ellipse parameters detected by inverting one of the images in the left-right direction is set to one set. Is calculated as the degree of symmetry of the left and right steering wheels 15 on the image. For this reason, the processing load can be reduced as compared with the first embodiment in which the degree of symmetry is calculated by image matching. Further, among the plurality of ellipse parameters by calculating the symmetry with a large weighting in the sensitive ellipse parameters to changes in the steering wheel steering angle theta _R, improved symmetry calculation accuracy of the correction value It can be improved calculation accuracy of theta _a.

(Modification)
Next, a steering angle correction system according to a modification of the embodiment of the present invention will be described. Although construction of the steering angle correction system A according to the modified example is the same as the first embodiment, without calculating the probability distribution of symmetry, calculates a correction value theta _a when a set of images are symmetric The point to do is different.

  As in the first embodiment, the steering angle correction device 13 according to the modification includes an acquisition unit 26, a correction device storage unit 27, an extraction unit 28, and a calculation unit 29. Since the acquisition unit 26 and the extraction unit 28 are the same as those in the first embodiment, description thereof will be omitted.

Correction apparatus storage section 27 stores a correction value theta _a to the arithmetic unit 29 calculates.

  The computing unit 29 calculates the symmetry degree of the left and right steered wheels 15 on a set of images, as in the first embodiment. In the modification, either the correlation degree by image matching or the distance d between two points on the ellipse parameter space may be adopted as the symmetry degree. Hereinafter, an example will be described in which the degree of correlation by image matching between an image obtained by horizontally inverting one of a set of images and the other image is calculated and adopted as the degree of symmetry.

The computing unit 29 determines whether or not the shapes of the left and right steered wheels 15 on the set of images are bilaterally symmetric based on the calculated degree of symmetry (correlation degree). For example, when the correlation degree, which is the degree of symmetry, is greater than or equal to a predetermined threshold th ₄ , the shape is determined to be bilaterally symmetric. Calculating section 29, when the shape of the steering wheel 15 is determined to symmetrical the steering angle theta _m which the steering angle sensor detects the time of imaging of a set of images used for the calculation of symmetry, the steering angle sensor is detected This is determined as a deviation (detection deviation) Δθ between the steering angle θ _m to be operated and the actual steering angle θ _t of the steering. The arithmetic unit 29, as in the first embodiment, when the absolute value of the determined detection deviation Δθ is the predetermined threshold th ₃ or more, the correction apparatus storing unit 27 detects deviation Δθ as a correction value theta _a Remember.

  Next, correction value calculation processing executed by the steering angle correction system A according to the modification will be described with reference to the flowchart of FIG.

  First, the side camera imaging unit 18 of the left and right side cameras 11 generates a set of images obtained by simultaneously imaging the peripheral area of the moving body 10 including one of the left and right steering wheels 15 (step S200).

Next, the steering angle determination unit 19, via the in-vehicle network 100, the steering angle sensor acquires a steering angle theta _m detected at the same time as the imaging of a set of images in step S200 (step S201).

Next, the acquisition unit 26 of the steering angle correction device 13 acquires the set of images in step S200 and the steering angle θ _m detected by the steering angle sensor in step S201 in association with each other via the in-vehicle network 100, for example. (Step S202).

  Next, the extraction unit 28 performs edge detection on the set of images in step S202 (step S203).

  Subsequently, the extraction unit 28 performs ellipse detection on the set of images for which edge detection has been performed in step S203 (step S204).

  Next, the computing unit 29 calculates the degree of symmetry of the left and right steering wheels 15 on the set of images in step S202 (step S205). For example, the computing unit 29 performs image matching by inverting one of the pair of images subjected to ellipse detection in step S204, and calculates the degree of correlation of image matching as the degree of symmetry.

Subsequently, the calculation unit 29 determines whether or not the shapes of the left and right steering wheels 15 on the set of images in Step S202 are bilaterally symmetric (Step S206). For example, the arithmetic unit 29 determines, when the degree of correlation is symmetric degree is a predetermined threshold value th ₄ or more, shape symmetrical. When it is determined that the shape is symmetrical (step S206—Yes), the process proceeds to step S207. On the other hand, when it is determined that the shape is not symmetrical (No in step S206), the process returns to step S200.

In step S206, when the shape is determined to symmetric (step S206-Yes), the arithmetic unit 29 determines the steering angle theta _m which the steering angle sensor has detected in step S202 as detected shift [Delta] [theta], the detected shift [Delta] [theta] It is determined whether or not the absolute value is greater than or equal to a predetermined threshold th ₃ (step S207). When the absolute value of the detected deviation Δθ is the threshold value th ₃ or more (step S207-Yes), the process proceeds to step S208. On the other hand, when the absolute value of the detected displacement Δθ is smaller than the threshold th ₃ (step S207-No), the process ends.

In step S207, when the absolute value of the detected deviation Δθ is the threshold value th ₃ or more (step S207-Yes), the arithmetic unit 29, is stored in the correction device the storage unit 27 the detected deviation Δθ as a correction value theta _a (step S208 ).

Thus, according to the steering angle correction system of the modified example, each time a set of images and the steering rudder angle θ _m detected by the rudder angle sensor are acquired in association with each other, both images are calculated based on the calculated symmetry. It is determined whether or not the shapes of the left and right steering wheels 15 are symmetrical. When the shape is determined to symmetrical calculates a correction value theta _a. For this reason, unlike the first embodiment, there is no need to store data in which the steering angle θ _m detected by the steering angle sensor is associated with the degree of symmetry in the correction device storage unit 27, and the data capacity to be stored is reduced. it can.

  Although the present invention has been described based on the drawings and embodiments, it should be noted that those skilled in the art can easily make various changes and modifications based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention.

  For example, each component in the steering angle correction system can be divided and rearranged. For example, the steering angle correction device 13 may be included in the imaging device. Further, for example, the steering angle correction system may further include a navigation device that supports the driver, and the navigation device may include a calculation unit 29 of the steering angle correction device 13 and an image superimposing unit 24 of the rear camera 12. .

  In the above-described embodiment, the acquisition unit 26 of the rudder angle correction device 13 acquires the image of the side camera 11 via the in-vehicle network 100, but may be configured to acquire via a dedicated line.

Moreover, you may provide the structure which discriminate | determines whether the ellipse detected by the extraction part 28 has extracted the steering wheel 15 correctly. For example, it is conceivable to determine whether or not the steered wheels 15 are extracted using the color information of the image before performing edge detection within the detected ellipse on the image. In this manner, by improving the accuracy of calculation of the degree of symmetry to improve the extraction accuracy of the steering wheel 15 on the image can be improved calculation accuracy of the correction value theta _a.

In the above embodiment, the steering angle correction device 13 is to store the calculated correction value theta _a in the correction unit storage unit 27, and transmits the correction value theta _a to steering angle sensor, a steering angle sensor You may comprise so that an output value may be correct | amended. In this case, the image superimposing unit 24 does not need to correct the steering angle obtained via the in-vehicle network 100, and thus the processing burden can be reduced.

  In the above-described embodiment, the image superimposing unit 24 superimposes the index 30 on the captured image of the rear camera 12. For example, the image superimposing unit 24 superimposes the index 30 on the captured image of the front camera that captures the peripheral image in front of the moving body 10. It may be configured.

  Further, in the above-described embodiment, the distance between two points on the parameter space based on the degree of correlation by image matching or the elliptic parameter is used as the degree of symmetry. However, the symmetry of the shapes of the left and right steering wheels 15 on a set of images. Any index can be adopted as long as it is an index indicating the degree.

DESCRIPTION OF SYMBOLS 10 Moving body 11 Side camera 12 Rear camera 13 Steering angle correction apparatus 14 Display part 15 Steering wheel 16 Side mirror 17 Optical system 18 Side camera imaging part 19 Steering angle judgment part 20 Side camera control part 21 Optical system 22 Rear camera imaging part 23 Rear camera storage unit 24 Image superposition unit 25 Rear camera control unit 26 Acquisition unit 27 Correction device storage unit 28 Extraction unit 29 Calculation unit 30 Index 31 Vehicle width extension line 32 Distance reference line 100 In-vehicle network

Claims (8)

Obtaining a set of images obtained by simultaneously imaging the left and right steered wheels and the steering angle of the moving body at the time of capturing the set of images in association with each other;
Calculating the degree of symmetry of the left and right steered wheels on the set of images;
Calculating a correction value for correcting the steering angle based on the degree of symmetry. A method for correcting the steering angle. The rudder angle correction method according to claim 1,
Acquiring the set of images at different steering angles;
In the step of calculating the correction value, the correction value is calculated based on the distribution of the symmetry with respect to the steering angle. The rudder angle correction method according to claim 1 or 2,
Extracting the left and right steered wheels on the set of images by ellipse detection;
In the step of calculating the degree of symmetry, the degree of symmetry is calculated using a parameter of an ellipse to be detected. The rudder angle correction method according to claim 3,
In the step of calculating the degree of symmetry, the parameter indicating at least one of the short side and the inclination of the ellipse is weighted more than the other parameters to calculate the degree of symmetry, and the rudder angle correction is characterized in that Method. The rudder angle correction method according to claim 1 or 2,
In the step of calculating the degree of symmetry, the degree of symmetry is calculated using a degree of correlation based on image matching based on the set of images. An acquisition unit that acquires a set of images obtained by simultaneously imaging the left and right steering wheels, and a steering angle of a moving body when the set of images is captured;
A steering angle correction apparatus comprising: an arithmetic unit that calculates a correction value for correcting the steering angle based on a degree of symmetry between the left and right steering wheels on the set of images. A rudder angle correction device according to claim 6;
A first imaging unit that generates the set of images;
A second imaging unit that generates a peripheral image obtained by imaging a peripheral region of the moving body;
An imaging apparatus comprising: an image superimposing unit that superimposes an index on the peripheral image based on the correction value. A first imaging unit that generates a set of images obtained by simultaneously imaging the left and right steering wheels;
An acquisition unit that associates and acquires the set of images and the steering angle of the moving body at the time of capturing the set of images;
An arithmetic unit that calculates a correction value for correcting the steering angle based on the symmetry of the left and right steering wheels on the set of images;
A second imaging unit that generates a peripheral image obtained by imaging a peripheral region of the moving body;
An image superimposing unit that superimposes an index on the peripheral image based on the correction value;
A steering angle correction system comprising: a display unit that displays a peripheral image on which the index is superimposed.

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