Truck suspension shaft lifting state detection method based on image processing technology

Abstract

The invention discloses a truck suspension axle lifting state detection method based on an image processing technology, and the method mainly comprises the following steps: obtaining a truck side image, detecting tires through a deep learning method, and obtaining the axle center and the axle number; for a truck with two or more axles, the axle centers are sequenced according to the abscissa according to the head position; judging the suspension state of each intermediate shaft according to the angle relation of adjacent axis connecting lines from the head of the truck, and then judging the suspension state of the last shaft, namely the tail shaft, of the truck; and finally, counting the number of the axles in the suspension state and axle serial numbers and giving axle suspension state information. The state of the suspension shaft of the truck can be automatically detected without manual intervention, whether the truck has the suspension shaft in the lifting state or not can be effectively recognized, statistics is conducted in time, and the defect that the suspension shaft is difficult to detect in the prior art is effectively overcome; therefore, vicious fee evasion and omission behaviors of a truck driver at a toll station caused by lifting of the suspension shaft are prevented.

Description

Technical Field

[0001] The invention relates to the field of image processing, and in particular to a method for detecting the lifting state of a truck suspension axle based on image processing technology. Background Art

[0002] The suspended axle is a structure commonly found on trucks. When the truck is unloaded or lightly loaded, the suspended axle can be lifted to reduce tire wear and fuel consumption.

[0003] According to the industry standard "Classification of Vehicle Types for Toll Road Vehicle Tolls" (JT / T 489-2019), the classification of truck types is determined based on factors such as the total number of axles (including suspended axles), vehicle length and total mass. In order to evade fees, some drivers deliberately lift the suspended axle when weighing at the toll station, artificially causing "axle loss" to achieve the purpose of paying less fees. However, the current detection technology of traditional toll stations has certain limitations in dealing with such evasion behaviors. Summary of the invention

[0004] In view of the shortcomings of the background technology, the present invention provides a method for detecting the lifting state of a truck suspension axle based on image processing technology, the method comprising the following steps:

[0005] Step S1, obtaining a side image of a truck that can display all tires on one side of the truck;

[0006] Step S2, using a deep learning method to detect tires from the side image of the truck, and obtain the axle center and the number of axles;

[0007] Step S3, if the number of axles is greater than 2, proceed to the next step; otherwise, there is no suspended axle, go to step S10;

[0008] Step S4, obtaining the position information of the front of the truck in the side image of the truck;

[0009] Step S5, if the front of the truck is located on the left side of the image, the axle centers are arranged in ascending order according to the horizontal coordinates; otherwise, the axle centers are arranged in descending order according to the horizontal coordinates;

[0010] Step S6, starting from the first axle of the front of the truck, connecting the axis centers of two adjacent axles in sequence and calculating the angle of each connecting line;

[0011] Step S7, determining the suspension state of each intermediate shaft starting from the front direction of the truck according to the angle relationship between the connecting lines of adjacent shaft centers;

[0012] Step S8, if the number of non-suspended axles is greater than or equal to 2, proceed to the next step; otherwise, determine that the last axle of the truck, i.e., the end axle, is a non-suspended axle, and go to step S10;

[0013] Step S9, determining the suspension state of the last axis according to the relationship between the angle between the axis centers of the last two non-suspended axes and the angle between the axis centers of the last non-suspended axis and the last axis;

[0014] Step S10, counting the number of axles in the suspended state and the corresponding axle numbers;

[0015] Step S11, providing axle suspension state information;

[0016] The intermediate axes in step S7 are other axles except the first axis and the last axis. The specific method for determining the suspension state of each intermediate axis starting from the front direction of the truck is as follows: suppose the axis center of the current axis to be determined to be in suspension state is P2, the axis center of the previous axis adjacent to the current axis is P1, the axis center of the next axis adjacent to the current axis is P3, the angle of the line connecting P1 and P2 is α1, and the angle of the line connecting P2 and P3 is α2; when the front of the truck is located on the left side of the image, if α1<α2 and |α1-α2|>θ, then the current axis is determined to be in suspension state and this axis is a suspended axis, otherwise the current axis is determined to be non-suspended state and this axis is a non-suspended axis; when the front of the truck is located on the right side of the image, if α1>α2 and |α1-α2|>θ, then the current axis is determined to be in suspension state and this axis is a suspended axis, otherwise the current axis is determined to be non-suspended state and this axis is a non-suspended axis; wherein θ is a set angle threshold.

[0017] Compared with the background technology, the beneficial effects of the present invention are as follows: the present invention detects the lifting state of the truck's suspended axle based on image processing technology, and can automatically detect the state of the truck's suspended axle without manual intervention. Through deep learning technology to detect tires and identify the number and position of axles, it can effectively identify whether the truck has a suspended axle in a lifted state, and make statistics in real time, effectively solving the problem that traditional toll station technology is difficult to detect suspended axles, thereby preventing toll evasion caused by the lifting of suspended axles. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flow chart of the steps of the method of the present invention;

[0019] Figure 2 is a side image of a truck in the embodiment;

[0020] Figure 3 is the tire detection result and the axle axis mark image of the embodiment;

[0021] Figure 4 This is a schematic diagram of the calculation of the axis connection angle;

[0022] Figure 5 This is a schematic diagram for determining the suspension state of the intermediate shaft;

[0023] Figure 6is an image of a detection result of axle suspension state of an embodiment;

[0024] Figure 7 is the axle suspension state detection result image of Example 2;

[0025] Figure 8 is the axle suspension state detection result image of Example 3;

[0026] Fig. 9 is an image of the axle suspension state detection result of Example 4;

[0027] Fig.10 This is an image of the axle suspension state detection result of Example 5. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] like Figure 1 As shown, the steps of the method of the present invention are:

[0030] Step S1, obtaining a side image of a truck that can display all tires on one side of the truck

[0031] Get the side image of the truck, such as Figure 2 As shown, this image shows all the tires on one side of the truck.

[0032] Step S2: Detect tires from the side image of the truck using a deep learning method to obtain the axle center and axle number

[0033] The trained deep learning tire detection model is used to detect tires from the truck side image, and the center of the tire's circumscribed rectangle is determined as the axis of the axle. The axis coordinates are the image coordinates of the truck side image, that is, the origin is located in the upper left corner of the image, the horizontal coordinate is positive to the right, and the vertical coordinate is positive downward. When the tire is detected, the number of axles of the truck can be obtained.

[0034] The tire circumscribed rectangle and the axis marked with "×" detected in this embodiment are as follows: Figure 3 As shown, the truck has 6 axles.

[0035] Step S3: If the number of axles is greater than 2, proceed to the next step; otherwise, there is no suspended axle, go to step S10

[0036] According to the number of axles detected in step S2, if the number of axles is greater than 2, there may be a suspended axle, and the next step is performed; otherwise, there is no suspended axle, and the process goes to step S10.

[0037] In this embodiment, the number of axles detected is 6, and there may be a suspended axle, so it is necessary to proceed to step S4 for subsequent processing.

[0038] Step S4, obtaining the position information of the front of the truck in the side image of the truck

[0039] The position information of the front of the truck in the side image of the truck is obtained. The position of the front of the truck in the side image of the truck is the position of the front of the truck relative to the rear of the truck in the side image of the truck. If the front of the truck is on the left side of the rear of the truck, the front of the truck is located on the left side of the image; if the front of the truck is on the right side of the rear of the truck, the front of the truck is located on the right side of the image.

[0040] In this embodiment, the front of the truck is on the left side of the rear of the truck, so it is determined that the front of the truck is located on the left side of the image.

[0041] Step S5: If the front of the truck is on the left side of the image, the axle centers are arranged in ascending order according to the horizontal coordinates; otherwise, the axle centers are arranged in descending order according to the horizontal coordinates.

[0042] According to the truck head position obtained in step S4 and the axle axis coordinates obtained in step S2, the axle axis horizontal coordinates are sorted. If the truck head is located on the left side of the image, the axle axis is sorted in ascending order according to the horizontal coordinates; otherwise, the axle axis is sorted in descending order according to the horizontal coordinates.

[0043] In this embodiment, since the front of the truck is located on the left side of the image, the axle centers need to be arranged in ascending order according to the horizontal coordinates.

[0044] Step S6, starting from the first axle of the front of the truck, connect the axles of two adjacent axles in sequence and calculate the angle of each connecting line

[0045] According to the axle centers obtained in step S2, the centers of two adjacent axles are connected in sequence starting from the first axle of the front of the truck and the angles of each connecting line are calculated. The angle of the connecting line of the centers of the two adjacent axles is calculated by the following method: a horizontal line is rotated clockwise or counterclockwise around any of the two axle centers by an acute angle so that the horizontal line coincides with the connecting line of the centers of the two axles or its extension line. The angle of rotation is the angle of the connecting line of the centers of the two adjacent axles. The angle is positive when rotating clockwise and negative when rotating counterclockwise, such as Figure 4 shown.

[0046] Step S7, determining the suspension state of each intermediate shaft starting from the front direction of the truck according to the angle relationship of the adjacent axis connection line

[0047] The other axles except the first axle and the last axle (i.e. the last axle) are intermediate axles. The specific method for determining the suspension state of each intermediate axle starting from the front direction of the truck is as follows: let the axis center of the current axle to be determined for the suspension state be P2, the axis center of the previous axle adjacent to the current axle be P1, the axis center of the next axle adjacent to the current axle be P3, the angle of the line connecting P1 and P2 be α1, and the angle of the line connecting P2 and P3 be α2; when the front of the truck is located on the left side of the image, if α1<α2 and |α1-α2|>θ, then the current axle is determined to be in a suspended state, and this axle is a suspended axle, otherwise the current axle is determined to be in a non-suspended state, and this axle is a non-suspended axle; when the front of the truck is located on the right side of the image, if α1>α2 and |α1-α2|>θ, then the current axle is determined to be in a suspended state, and this axle is a suspended axle, otherwise the current axle is determined to be in a non-suspended state, and this axle is a non-suspended axle; where θ is the set angle threshold, such as Figure 5 shown.

[0048] In this embodiment, the truck is a 6-axle truck, the front of the truck is located on the left side of the image, and the angle threshold θ is defined as 7°. The angle α1 of the line connecting the axis center of the first axis and the axis center of the second axis is -15.6°, the angle α2 of the line connecting the axis center of the second axis and the axis center of the third axis is 1.7°, |α1-α2|=17.3°>θ, and α1<α2, so the second axis is determined to be a suspended axis; the angle α3 of the line connecting the axis center of the third axis and the axis center of the fourth axis is -11.1°, |α2–α3|=12.8°>θ but α2>α3, so the third axis is determined to be a non-suspended axis; the angle α4 of the line connecting the axis center of the fourth axis and the axis center of the fifth axis is -10.6°, |α3–α4|=0.5°<θ, so the fourth axis is determined to be a non-suspended axis; the angle α5 of the line connecting the axis center of the fifth axis and the axis center of the sixth axis is -8.6°, |α4–α5|=2.0°<θ, so the fifth axis is determined to be a non-suspended axis.

[0049] Step S8: If the number of non-suspended axles is greater than or equal to 2, proceed to the next step; otherwise, the last axle of the truck is determined to be a non-suspended axle, and the process goes to step S10.

[0050] If the number of axles other than the final axle that are determined to be non-suspended axles is greater than or equal to 2, the final axle may be a non-suspended axle or a suspended axle in a lifted state, and therefore further determination is required through step S9. Otherwise, the final axle can only be a non-suspended axle, and the process directly proceeds to step S10.

[0051] In this embodiment, the number of axles other than the final axle that are determined to be non-suspended axles is 4, including 3 intermediate axles and 1 first axle (the first axle starting from the front of the vehicle cannot be a suspended axle and can only be a non-suspended axle), which meets the condition that the number of non-suspended axles is greater than or equal to 2, so it is necessary to proceed to step S9 to determine the state of the final axle.

[0052] Step S9: Determine the suspension state of the last axis according to the relationship between the angle between the axis centers of the last two non-suspended axes and the angle between the axis centers of the last non-suspended axis and the last axis.

[0053] The specific method for determining the suspension state of the final axis is as follows: let the axis center of the last non-suspended axis be C1, the axis center of the second-to-last non-suspended axis be C2, the axis center of the final axis be C3, the angle of the line connecting C1 and C2 be β1, the angle of the line connecting C2 and C3 be β2, if |β1-β2|>θ, then the final axis is determined to be in a suspension state, otherwise the final axis is determined to be in a non-suspended state; wherein θ is a set angle threshold, which is the same as the angle threshold set in step S7.

[0054] In this embodiment, the angle β1 of the line connecting the axis center of the penultimate non-suspended axis and the axis center of the second-to-last non-suspended axis is -10.4°, the angle β2 of the line connecting the axis center of the penultimate non-suspended axis and the axis center of the last axis is -8.6°, |β1-β2|=1.8°<θ, so the last axis, i.e., the sixth axis, is a non-suspended axis.

[0055] The axle suspension state detection result of this embodiment is as follows Figure 6 As shown, the axis with the axis center marked as "O" plus "+" is the suspended axis in the lifted state.

[0056] Step S10: Count the number of axles in the suspended state and the corresponding axle numbers

[0057] According to the detection results of the suspension state of the axles in the above steps, the number of axles in the suspension state is counted, and the corresponding axle numbers in the suspension state are counted. The axle numbers start with the first axle number as 1, and increase by 1 in order from the first axle to the last axle.

[0058] In this embodiment, the truck has one suspended axle in a lifted state, and the corresponding axle number is 2.

[0059] Step S11, providing axle suspension status information

[0060] Finally, the suspension status information of the axle of the truck under test is given, including the number of axles, the number of suspended axles in the lifted state and the axle serial number.

[0061] In this embodiment, the axle suspension state information is provided as follows: the number of axles is 6, the number of suspension axles in the lifting state is 1, and the sequence number is 2.

[0062] In addition to providing the above-mentioned embodiments, the present invention also provides Figures 7 to 10 The remaining 4 embodiments are shown. Figure 7 The figure shows the axle suspension state detection result of Example 2, which is a 4-axle truck with the front of the truck located on the left, and the first intermediate axle and the last axle are suspended axles in a lifted state. Figure 8The figure shows the axle suspension state detection result of Example 3, which is a 4-axle truck with the front of the truck located on the left, and the rear axle is a suspended axle in a lifted state. Fig. 9 The figure shows the axle suspension state detection result of Example 4, which is a 5-axle truck with the front of the truck located on the right side and no suspended axle in the lifted state. Fig.10 The figure shows the axle suspension state detection result of Example 6, which is a three-axle truck with the front of the truck located on the right side, and the middle axle is a suspended axle in a lifted state.

[0063] The above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified, or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A method for detecting the lifting state of a truck suspension axle based on image processing technology, characterized in that: The following steps are involved: S1: Acquire a side image of a truck that can display all tires on one side of the truck; S2: Use deep learning methods to detect tires from the side image of the truck and obtain the axle center and number of axles; S3: If the number of axles is greater than 2, proceed to the next step; otherwise, there is no suspended axle, and go to S10; S4: Acquire the position information of the front of the truck in the side image of the truck; S5: If the front of the truck is located on the left side of the image, the axle centers are arranged in ascending order according to the horizontal coordinates; otherwise, the axle centers are arranged in descending order according to the horizontal coordinates; S6: Starting from the first axle of the front of the truck, connect the axle centers of two adjacent axles in sequence and calculate the angle of each connecting line; S7: Determine the suspension state of each intermediate shaft starting from the front direction of the truck according to the angle relationship of the connecting lines of adjacent shaft centers; S8: If the number of non-suspended axles is greater than or equal to 2, proceed to the next step; otherwise, determine that the last axle of the truck, i.e., the end axle, is a non-suspended axle, and go to S10; S9: determining the suspension state of the last axis according to the relationship between the angle between the axis centers of the last two non-suspended axes and the angle between the axis centers of the last non-suspended axis and the last axis; S10: Count the number of axles in the suspended state and the corresponding axle numbers; S11: Provide axle suspension status information; The intermediate axes in step S7 are other axles except the first axis and the last axis. The specific method for determining the suspension state of each intermediate axis starting from the front direction of the truck is as follows: suppose the axis center of the current axis to be determined to be in suspension state is P2, the axis center of the previous axis adjacent to the current axis is P1, the axis center of the next axis adjacent to the current axis is P3, the angle of the line connecting P1 and P2 is α1, and the angle of the line connecting P2 and P3 is α2; when the front of the truck is located on the left side of the image, if α1<α2 and |α1-α2|>θ, then the current axis is determined to be in suspension state and this axis is a suspended axis, otherwise the current axis is determined to be non-suspended state and this axis is a non-suspended axis; when the front of the truck is located on the right side of the image, if α1>α2 and |α1-α2|>θ, then the current axis is determined to be in suspension state and this axis is a suspended axis, otherwise the current axis is determined to be non-suspended state and this axis is a non-suspended axis; wherein θ is a set angle threshold.

2. The method for detecting the lifting state of a truck suspension axle based on image processing technology according to claim 1 is characterized in that: In step S2, the axle center is determined by using a deep learning method to obtain the center of the circumscribed rectangle of the tire detected from the side image of the truck, and the axis center coordinates are the image coordinates of the side image of the truck, that is, the origin is located in the upper left corner of the image, the horizontal coordinate is positive to the right, and the vertical coordinate is positive downward.

3. The method for detecting the lifting state of a truck suspension axle based on image processing technology according to claim 1 is characterized in that: In step S4, the position of the front of the truck in the side image of the truck is the position of the front of the truck relative to the rear of the truck in the side image of the truck. If the front of the truck is on the left side of the rear of the truck, the front of the truck is located on the left side of the image; if the front of the truck is on the right side of the rear of the truck, the front of the truck is located on the right side of the image.

4. The method for detecting the lifting state of a truck suspension axle based on image processing technology according to claim 1 is characterized in that: In step S6, the angle of the axis line connecting the two adjacent axles is calculated by the following method: a horizontal line is rotated around any one of the two axle axes clockwise or counterclockwise by an acute angle so that the horizontal line coincides with the axis line connecting the two axles or its extension line. The rotation angle is the angle of the axis line connecting the two adjacent axles, which is positive for clockwise rotation and negative for counterclockwise rotation.

5. The method for detecting the lifting state of a truck suspension axle based on image processing technology according to claim 1 is characterized in that: The specific method for determining the suspension state of the final axis in step S9 is as follows: assuming that the axis center of the last non-suspended axis is C1, the axis center of the second-to-last non-suspended axis is C2, the axis center of the final axis is C3, the angle of the line connecting C1 and C2 is β1, and the angle of the line connecting C2 and C3 is β2. If |β1-β2|>θ, the final axis is determined to be in a suspension state, otherwise the final axis is determined to be in a non-suspended state; wherein θ is a set angle threshold, which is the same as the angle threshold set in step S7.

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