An automatic edge-finding device and method based on thick plate 3D visual inspection system

Abstract

The present invention discloses an automatic edge-finding device and method based on a 3D visual inspection system for thick plates, comprising an inspection bracket, a track, a base and a PLC controller, wherein the 3D visual inspection system for thick plates comprises an imaging unit; the inspection bracket is arranged above or below the thick plate; the track is arranged horizontally on the inspection bracket and is arranged parallel to the surface of the thick plate; the base is arranged on the track, and the number is an even number, each of the bases is provided with a servo motor and the imaging unit, and the servo motor drives the base to move along the track; the servo motor is controlled by the PLC controller. The present invention enables the 3D visual inspection system to automatically find the edge of a single thick plate or two thick plates after splitting, thereby realizing automatic detection and identification of 3D defects on the edge of the thick plate.

Description

Technical Field

[0001] The present invention relates to machine vision detection technology, and more specifically, to an automatic edge-finding device and method based on a thick plate 3D vision detection system. Background Art

[0002] Surface quality is an important factor affecting the overall quality of thick plates. In recent years, online detection systems for thick plate surface quality have been widely used. At present, most of the online detection systems for thick plates used on site are traditional two-dimensional imaging detection systems. Due to the complex background and many interference factors of thick plates, it is difficult to effectively detect defects. In response to this situation, 3D visual inspection systems have begun to be used in the field of thick plate inspection.

[0003] The 3D visual inspection system can effectively overcome the false detection of defects caused by background interference in the 2D imaging inspection system by judging the depth of defects. In addition, for thick plate steel products, the area where defects occur is mainly concentrated on the edge of the thick plate. However, on the thick plate finishing line, the specifications of the thick plate vary greatly, the position of the edge of the thick plate varies greatly, and two split plates pass through at the same time. In this way, the 3D visual inspection system needs to have an automatic edge search function to realize automatic detection and identification of edge defects.

[0004] In existing patent applications, such as the Chinese patent for an image acquisition method for an online detection system for surface defects of ultra-wide and thick plates (application number 201910647988.3), the number of linear array cameras used is determined based on the maximum width of the plate surface, the minimum size of the defects to be detected, and the camera resolution, and the number of narrow-band LED light sources and the number of cameras are kept consistent. After the steel plate enters the camera acquisition area, the laser velocimeter obtains the speed of the steel plate, thereby determining the acquisition line rate of the linear array camera. However, this patent only introduces an image acquisition method for a two-dimensional imaging detection system for online detection of thick plates, and does not involve the adjustment of the imaging system.

[0005] Another example is the Chinese patent for strip surface defect detection device and method (application number 201310127783.5), which introduces an imaging method of setting a plane mirror on the surface to be detected of the strip or thick plate. The plane mirror is at a certain angle to the surface to be detected, so that the surface to be detected is imaged in the plane mirror. However, this patent is mainly a design method for imaging optical path, and also does not involve the position adjustment of the imaging system. Summary of the invention

[0006] In view of the above-mentioned defects existing in the prior art, the purpose of the present invention is to provide an automatic edge-finding device and method based on a thick plate 3D visual inspection system, so that the 3D visual inspection system can automatically find the edges of a single thick plate or two thick plates after splitting, thereby realizing automatic detection and identification of 3D defects on the edges of thick plates.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] In one aspect, an automatic edge-finding device based on a thick plate 3D visual inspection system comprises a detection bracket, a track, a base and a PLC controller, wherein the thick plate 3D visual inspection system comprises an imaging unit;

[0009] The detection bracket is arranged above or below the thick plate;

[0010] The track is horizontally arranged on the detection bracket and is arranged parallel to the surface of the thick plate;

[0011] The bases are arranged on the track, and the number is an even number, each of the bases is provided with a servo motor and the imaging unit, and the servo motor drives the base to move along the track;

[0012] The servo motor is controlled by the PLC controller.

[0013] Preferably, the number of the bases is four.

[0014] Preferably, an anti-collision mechanism is provided on the base.

[0015] The anti-collision mechanism comprises a detection rod arranged on the first base, the second base and the third base, and a photoelectric induction switch arranged on the second base, the third base and the fourth base.

[0016] On the other hand, an automatic edge finding method based on a thick plate 3D visual inspection system is provided, wherein the automatic edge finding device based on the thick plate 3D visual inspection system is arranged above or below the thick plate, and then the following automatic edge finding process is performed:

[0017] 1) Before the thick plate arrives at the inspection position, the thick plate 3D visual inspection system obtains the production information of the thick plate in advance;

[0018] 2) The thick plate 3D visual inspection system calculates the adjustment position of each of the imaging units according to the production information of the thick plate;

[0019] 3) The thick plate 3D visual inspection system sends the adjusted position of the imaging unit to the PLC controller, and the PLC controller controls the servo motor to adjust the imaging unit to its home position;

[0020] 4) After the imaging unit completes position adjustment, it performs automatic edge-finding position adjustment and waits for the thick plate to pass.

[0021] Preferably, in the step 1), the production information of the thick plate includes the width of the thick plate and whether the thick plate is a split plate.

[0022] Preferably, in step 2), the thick plate 3D visual inspection system calculates the adjustment position of each imaging unit as follows:

[0023] When the thick plate is not a split plate, P1=0, P2=P1+FOV=FOV, P3=W-1.5*FOV, P4=W-0.5*FOV;

[0024] When the thick plate is a split plate, P1=0, P2=(W-FOV) / 2, P3=(W+FOV) / 2, P4=W-0.5*FOV;

[0025] In the above formula, P1 represents the position of the imaging unit on the first base, P2 represents the position of the imaging unit on the second base, P3 represents the position of the imaging unit on the third base, P4 represents the position of the imaging unit on the fourth base, FOV represents the field of view of the imaging unit, and W represents the width of the thick plate.

[0026] Preferably, in step 3), the homing adjustment of the imaging unit is specifically as follows:

[0027] The first base is not adjustable and is in a fixed position;

[0028] The second base approaches the first base, and stops moving when the photoelectric sensor switch on the second base reaches the detection rod on the first base, and the second base reaches the starting position;

[0029] The third base approaches the second base, and stops moving when the photoelectric sensor switch on the third base reaches the detection rod on the second base, and the third base reaches the starting position;

[0030] The fourth base approaches the third base, and stops moving when the photoelectric sensor switch on the fourth base reaches the detection rod on the third base, and the fourth base reaches the starting position.

[0031] Preferably, in step 4), the automatic edge-finding position adjustment of the imaging unit is specifically as follows:

[0032] The fourth base automatically adjusts the edge position according to the position value calculated by the thick plate 3D visual inspection system, and then starts the automatic edge position adjustment of the third base and the second base in sequence.

[0033] The present invention provides an automatic edge-finding device and method based on a thick plate 3D visual inspection system. After obtaining the production line production information, the lateral position of each imaging unit is determined. The inspection system sends the relevant adjustment information to the PLC control unit. The PLC control unit completes the adjustment of the lateral position of the imaging unit through the servo motor, so that the imaging system can realize automatic detection and identification of thick plate edge defects. For different width specifications and split plates, the imaging unit position can be automatically adjusted to the edge of the thick plate, and the imaging of the thick plate edge can be completed in cooperation with the inspection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of a single thick plate passing through a conveyor roller;

[0035] Figure 2 It is a schematic diagram of two thick plates passing through the conveyor roller after splitting;

[0036] Figure 3 It is a schematic diagram of the automatic edge-finding device based on the thick plate 3D visual inspection system of the present invention for inspecting two thick plates after segmentation;

[0037] Figure 4 It is a schematic diagram of the automatic edge-finding device based on the thick plate 3D visual inspection system of the present invention for inspecting a single thick plate;

[0038] Figure 5 It is a schematic diagram of the on-site arrangement of the automatic edge-finding device based on the thick plate 3D visual inspection system of the present invention. DETAILED DESCRIPTION

[0039] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0040] Since there are two types of thick plates passing through the thick plate finishing production line, it is necessary to consider the realization of the automatic edge finding function of a single thick plate or two thick plates after splitting. Figure 1 As shown, when a single thick plate 1 passes through the detection position of the automatic edge-finding device based on the thick plate 3D visual detection system of the present invention, it is necessary to detect the edges on both sides of the thick plate 1; Figure 2As shown, when the two thick plates 2 after splitting pass through the detection position of the automatic edge-finding device based on the thick plate 3D visual inspection system of the present invention, it is necessary to detect the edges of the two thick plates 2 after splitting at the same time, and four imaging units are required. Therefore, for the online detection of the surface quality of the finishing area of ​​the thick plate, at least four imaging units are required for defect detection on the upper and lower surfaces respectively, and the lateral positions of these four imaging units need to be adjusted. When the thick plate passes through the detection position, whether it is a single thick plate 1 or two thick plates 2 after splitting, they are all transported close to the transmission side. Therefore, when the width specification of the thick plate changes, the first imaging unit 9 close to the transmission side does not need to be adjusted, and only the second to fourth imaging units 9, 10, 11 away from the transmission side need to be adjusted.

[0041] Please combine Figure 3 and Figure 4 As shown, an automatic edge-finding device based on a thick plate 3D visual inspection system provided by the present invention includes a detection bracket 3, a track 4 and a base.

[0042] The detection bracket 3 is located above and / or below the thick plate, corresponding to the upper surface and / or lower surface of the thick plate.

[0043] The track 4 is horizontally mounted on the detection bracket 3 so that the track 4 is parallel to the surface of the thick plate.

[0044] The base is installed on the track 4, and the number is set to four (such as Figure 3 As shown in the figure, from left to right there are the first base 5, the second base 6, the third base 7, and the fourth base 8), each base is provided with a servo motor and an imaging unit (the first base 5 is the first imaging unit 9, the second base 6 is the second imaging unit 10, the third base 7 is the third imaging unit 11, and the fourth base 8 is the fourth imaging unit 12), and the servo motor drives the base to move along the track 4 for lateral position adjustment.

[0045] The servo motor is controlled by the PLC controller. The thick plate 3D visual inspection system receives the production information on site, mainly the width information of the thick plate, whether it is a split plate, etc. The thick plate 3D visual inspection system determines the position of each imaging unit that needs to be adjusted according to the production information, and sends the position information to the PLC. The PLC controller controls each servo motor to drive the corresponding base to complete the position adjustment of the first imaging unit 9 to the fourth imaging unit 12.

[0046] In order to prevent the imaging units from colliding with each other during the lateral position adjustment process, an anti-collision mechanism is provided on each base.

[0047] The anti-collision mechanism includes a detection rod 13 arranged on the first base 5 , the second base 6 and the third base 7 , and a photoelectric sensor switch 14 arranged on the second base 6 , the third base 7 and the fourth base 8 .

[0048] When the detection rod 13 reaches the position where the photoelectric sensor switch 14 is located, the imaging unit where the detection rod 13 is located stops adjusting its position, thereby achieving a collision protection function.

[0049] Please refer to Figure 3 As shown, for the detection of the two thick plates 2 after splitting, the fourth imaging unit 12 farthest from the transmission side among the four imaging units is first position adjusted. After adjustment, the third imaging unit 11 is position adjusted, and then the second imaging unit 10 is adjusted, and so on. The first imaging unit 9 closest to the transmission side is not position adjusted.

[0050] Please refer to Figure 4 As shown, for the inspection of a single thick plate 1, only two edges need to be inspected, so two imaging units are grouped together (the first imaging unit 9 and the second imaging unit 10 are grouped together, and the third imaging unit 11 and the fourth imaging unit 12 are grouped together) to inspect the left and right edges of the single thick plate 1. The adjustment position is calculated by the production information obtained by the thick plate 3D visual inspection system and sent to the PLC controller, which controls each servo motor to drive the corresponding base to complete the position adjustment of the first imaging unit 9 to the fourth imaging unit 12.

[0051] The present invention also provides an automatic edge-finding method based on a thick plate 3D visual inspection system, wherein the automatic edge-finding device based on a thick plate 3D visual inspection system of the present invention is arranged above or below the thick plate, corresponding to the upper surface or / and lower surface of the thick plate to be inspected. Then the following automatic edge-finding process is performed:

[0052] 1) Before the thick plate arrives at the inspection position, the thick plate 3D visual inspection system obtains the production information of the thick plate in advance; the production information of the thick plate includes the width of the thick plate and whether the thick plate is a split plate;

[0053] 2) The thick plate 3D visual inspection system calculates the adjustment position of each imaging unit based on the production information of the thick plate;

[0054] 3) The thick plate 3D visual inspection system sends the adjusted position of each imaging unit to the PLC controller, which controls the servo motor to drive the corresponding base to adjust the position of each imaging unit;

[0055] The first imaging unit 9 closest to the transmission side is not adjusted in position, and the second imaging unit 10 to the fourth imaging unit 12 return to the starting position: the second imaging unit 10 approaches the first imaging unit 9, and stops moving when the photoelectric sensor switch 14 on the second base 6 reaches the detection rod 13 on the first base 5, and the second imaging unit 10 on the second base 6 returns to the starting position. The third and fourth imaging units 11 and 12 are adjusted to return to the starting position in sequence: when the photoelectric sensor switch 14 on the third base 7 reaches the detection rod 13 on the second base 6, it stops moving, and the third imaging unit 11 on the third base 7 returns to the starting position. The position adjustment method of the fourth imaging unit 12 is the same as that of the third imaging unit 11;

[0056] 4) After the second to fourth imaging units 10, 11, and 12 complete the position adjustment, the fourth imaging unit 12 automatically performs edge-finding adjustment according to the position value provided by the thick plate 3D visual inspection system. After the position adjustment is completed, the third and second imaging units 11 and 10 are started in sequence. Finally, the four imaging units are all located at the set positions, waiting for the thick plate to be inspected to pass.

[0057] Example

[0058] Please combine Figure 5 As shown, the automatic edge-finding device based on the thick plate 3D visual inspection system of this embodiment is applied to the five-meter thick plate finishing production line of the steel plant, and the inspection bracket 3 is installed above and below the thick plate, corresponding to the upper surface and lower surface of the thick plate. The track 4 is horizontally erected on the inspection bracket 3, so that the track 4 is parallel to the surface of the thick plate, and the first base 5, the second base 6, the third base 7, and the fourth base 8 are installed on the track 4 in sequence, and the first imaging unit 9, the second imaging unit 10, the third imaging unit 11, and the fourth imaging unit 12 are correspondingly installed on each base. Each imaging unit can move laterally along the track 4, and each base is driven by a servo motor. The track 4 is composed of a rack and a sliding guide rail, and the imaging units are interlocked with each other through an anti-collision mechanism to prevent the bases from colliding with each other during the lateral position adjustment process.

[0059] Before the thick plate passes through the detection position, the thick plate 3D visual inspection system receives the secondary production information (L2) in advance, parses the plate width information W and the whole plate or split plate identification information flag (flag = 0 indicates a single thick plate, flag = 1 indicates two thick plates after splitting) contained therein, and calculates the lateral positions P1, P2, P3, P4 (where P1 = 0) of the first to fourth imaging units 9, 10, 11, 12 on this basis, and the field of view of each imaging unit represents FOV. The adjustment position of each imaging unit is as follows:

[0060] When the thick plate is not a split plate, P1=0, P2=P1+FOV=FOV, P3=W-1.5*FOV, P4=W-0.5*FOV;

[0061] When the thick plate is a split plate, P1 = 0, P2 = (W-FOV) / 2, P3 = (W+FOV) / 2, P4 = W-0.5*FOV;

[0062] In this embodiment, the 4200mm wide thick plate after splitting passes the detection position, and the edge of the thick plate close to the transmission side is used as the position adjustment reference (P1=0). The corresponding lateral positions of each imaging unit are P2=1950mm, P3=2250mm, and P4=4050mm, respectively, where the effective field of view of each imaging unit is 300mm.

[0063] If a whole thick plate of 4200mm width passes the detection position, with the edge of the thick plate close to the transmission side as the position adjustment reference (P1=0), the lateral positions of the corresponding imaging units are P2=300mm, P3=3750mm, and P4=4050mm respectively.

[0064] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. An automatic edge finding method for an automatic edge finding device based on a thick plate 3D visual inspection system, characterized in that: The automatic edge-finding device based on the thick plate 3D visual inspection system includes a detection bracket, a track, a base and a PLC controller, and the thick plate 3D visual inspection system includes an imaging unit; The detection bracket is arranged above or below the thick plate; The track is horizontally arranged on the detection bracket and is arranged parallel to the surface of the thick plate; The bases are arranged on the track, and the number is an even number, each of the bases is provided with a servo motor and the imaging unit, and the servo motor drives the base to move along the track; The servo motor is controlled by the PLC controller. The number of the bases is four, The base is provided with an anti-collision mechanism. The anti-collision mechanism includes a detection rod arranged on the first base, the second base and the third base, and a photoelectric sensor switch arranged on the second base, the third base and the fourth base. The automatic edge-finding device based on the thick plate 3D visual inspection system is arranged above or below the thick plate, and the automatic edge-finding method performs the following automatic edge-finding process: 1) Before the thick plate arrives at the inspection position, the thick plate 3D visual inspection system obtains the production information of the thick plate in advance; 2) The thick plate 3D visual inspection system calculates the adjustment position of each of the imaging units according to the production information of the thick plate; 3) The thick plate 3D visual inspection system sends the adjusted position of the imaging unit to the PLC controller, and the PLC controller controls the servo motor to adjust the imaging unit to its home position; 4) After the imaging unit completes the position adjustment, it automatically adjusts the edge position and waits for the thick plate to pass. In the step 1), the production information of the thick plate includes the width of the thick plate and whether the thick plate is a split plate. In the step 2), the thick plate 3D visual inspection system calculates the adjustment position of each imaging unit as follows: When the thick plate is not a split plate, P1=0, P2=P1+FOV=FOV, P3=W-1.5*FOV, P4=W-0.5*FOV; When the thick plate is a split plate, P1=0, P2=(W-FOV) / 2, P3=(W+FOV) / 2, P4=W-0.5*FOV; In the above formula, P1 represents the position of the imaging unit on the first base, P2 represents the position of the imaging unit on the second base, P3 represents the position of the imaging unit on the third base, P4 represents the position of the imaging unit on the fourth base, FOV represents the field of view of the imaging unit, and W represents the width of the thick plate.

2. The automatic edge finding method according to claim 1, characterized in that: In step 3), the homing adjustment of the imaging unit is specifically as follows: The first base is not adjustable and is in a fixed position; The second base approaches the first base, and stops moving when the photoelectric sensor switch on the second base reaches the detection rod on the first base, and the second base reaches the starting position; The third base approaches the second base, and stops moving when the photoelectric sensor switch on the third base reaches the detection rod on the second base, and the third base reaches the starting position; The fourth base approaches the third base, and stops moving when the photoelectric sensor switch on the fourth base reaches the detection rod on the third base, and the fourth base reaches the starting position.

3. The automatic edge finding method according to claim 2, characterized in that: In the step 4), the automatic edge-finding position adjustment of the imaging unit is specifically as follows: The fourth base automatically adjusts the edge position according to the position value calculated by the thick plate 3D visual inspection system, and then starts the automatic edge position adjustment of the third base and the second base in sequence.

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