A method and system for determining control timing of a linear array camera

Abstract

The application provides a determination method and a determination system for a control timing of a linear array camera. The method comprises the following steps: controlling the linear array camera to be turned on at a first opening timing and turned off at a first closing timing to obtain a first photographed image of a steel plate, and then obtaining a loss rate of the first photographed image; the loss rate is the sum of a frame loss rate and a line loss rate; controlling the linear array camera to be turned on at a second opening timing and turned off at the first closing timing to obtain a second photographed image of the steel plate; then obtaining a loss rate of the second photographed image; comparing the loss rates of the first photographed image and the second photographed image to obtain a target starting timing. The method compares the frame loss rate and the line loss rate of the images corresponding to different opening timings of the linear array camera, obtains the opening timing corresponding to the images with low frame loss rate and line loss rate, and takes the opening timing as the preferred opening timing, so that the quality of the images collected by the vision system is good, and the accuracy of the steel plate defect detection is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel plate surface defect detection, and particularly relates to a line array camera control timing determination method and a determination system. BACKGROUND

[0002] The surface of a medium-thick steel plate is complex, and there are a large number of non-defect interference objects such as iron oxide scales and water marks in various shapes, which are easily confused with real defects such as cracks and roll marks. Therefore, manual detection is extremely difficult. Methods such as eddy current detection, ultrasonic detection, and infrared detection mostly need to wait for the steel plate to cool down before detection. Generally, the cooling of a rolled steel plate takes 5-8 hours, and the defect detection after cooling is seriously lagging, and the defect detection caused by equipment failure is not timely, which will also cause batch defects, causing significant economic losses to the steel plant.

[0003] Therefore, surface defect detection technology based on machine vision has become the most widely used means for medium-thick steel plate surface defect detection with the advantages of high efficiency, real-time, traceability, and close to human eye perception. The defect detection process of machine vision mainly includes two key processes: defect image acquisition and classification recognition. Defect image acquisition is the first step of surface defect detection. In the prior art, a line array camera scans the surface of a steel plate row by row, and outputs an image based on the scanning results of several rows. The row frequency controls the scanning, and the frame frequency controls the output. When the line array camera starts image acquisition, the row frequency can be turned on first and then the frame frequency, or the frame frequency can be turned on first and then the row frequency. If the timing is not appropriate, it will cause image frame loss or row loss, resulting in poor image quality of the vision system and reducing the accuracy of steel plate defect detection. SUMMARY

[0004] In view of the above defects or deficiencies in the prior art, the present application aims to provide a line array camera control timing determination method and a determination system.

[0005] In a first aspect, the present application provides a line array camera control timing determination method, which is used for acquiring images of surface defects of a steel plate. The method comprises the following steps:

[0006] controlling the line array camera to be turned on at a first opening timing and turned off at a first closing timing to obtain a first photographed image of the steel plate; the first opening timing is to turn on the frame frequency first and then turn on the row frequency, and the first closing timing is to turn off the frame frequency first and then turn off the row frequency;

[0007] comparing the first photographed image with the actual surface of the steel plate to obtain a loss rate of the first photographed image; the loss rate is the sum of a frame loss rate and a row loss rate;

[0008] The control line array camera is opened under a second opening timing and is closed under the first closing timing, so as to obtain a second shooting image of the steel plate; the second opening timing is to open the line frequency first and then open the frame frequency;

[0009] The first shooting image is compared with the actual surface of the steel plate, so as to obtain the loss rate of the second shooting image;

[0010] The loss rates of the first shooting image and the second shooting image are compared, so as to obtain a target starting timing; the target opening timing is the opening timing of the line array camera corresponding to the smaller loss rate.

[0011] According to the technical scheme provided by the embodiment of the application, the shooting image corresponding to the target starting timing is a first target image; after the target starting timing is obtained, the following steps are further included:

[0012] The control line array camera is opened under the target opening timing and is closed under a second closing timing, so as to obtain a third shooting image of the steel plate; the second closing timing is to close the line frequency first and then close the frame frequency;

[0013] The third shooting image is compared with the actual surface of the steel plate, so as to obtain the loss rate of the third shooting image;

[0014] The loss rates of the first target image and the third shooting image are compared, so as to obtain a target closing timing; the target closing timing is the closing timing of the line array camera corresponding to the smaller loss rate.

[0015] According to the technical scheme provided by the embodiment of the application, the line array camera is controlled to be opened under different opening timings, and at least the following steps are included:

[0016] After receiving an entry signal, timing is started; when the entry signal lasts for a first preset time length, a first control signal is sent; the first control signal is used to control the line array camera to be opened under a corresponding opening timing; the entry signal is a signal that the steel plate enters a detection area.

[0017] According to the technical scheme provided by the embodiment of the application, the line array camera is controlled to be closed under different closing timings, and at least the following steps are included:

[0018] After receiving an exit signal, timing is started; when the exit signal lasts for a second preset time length, a second control signal is sent; the second control signal is used to control the line array camera to be closed under a corresponding closing timing; the exit signal is a signal that the steel plate leaves the detection area.

[0019] According to the technical scheme provided by the embodiment of the present application, the steel plate moves along a first direction; the line array camera is opened at a first opening timing and is closed at a first closing timing to obtain a first shooting image of the steel plate, and at least the following steps are included:

[0020] After the first control signal is sent, the line array camera is opened at the first opening timing, and the line array camera starts to scan the surface of the steel plate;

[0021] After the second control signal is sent, the line array camera is closed at the first closing timing, and the line array camera stops scanning the surface of the steel plate, and based on the scanning of the line array camera during the entire movement of the steel plate, the first shooting image of the steel plate is obtained.

[0022] According to the technical scheme provided by the embodiment of the present application, the frame frequency is opened, and at least the following steps are included:

[0023] The frame signal channel of the line array camera is set to high level.

[0024] According to the technical scheme provided by the embodiment of the present application, the frame frequency is closed, and at least the following steps are included:

[0025] The frame signal channel of the line array camera is set to low level.

[0026] According to the technical scheme provided by the embodiment of the present application, the horizontal frequency is opened, and at least the following steps are included:

[0027] The power switch of the synchronization box is turned on, and the synchronization box is powered on.

[0028] According to the technical scheme provided by the embodiment of the present application, the horizontal frequency is closed, and at least the following steps are included:

[0029] The power switch of the synchronization box is turned off, and the synchronization box is powered off.

[0030] In a second aspect, the present application provides a line array camera control timing determination system for completing the line array camera control timing determination method described above, and the system includes:

[0031] A control module configured to control the line array camera to be opened at a first opening timing and to be closed at a first closing timing, and to control the line array camera to be opened at a second opening timing and to be closed at the first closing timing;

[0032] The computing module is configured to compare the first photographed image with the actual surface of the steel plate to obtain a loss rate of the first photographed image, compare the first photographed image with the actual surface of the steel plate to obtain the loss rate of the second photographed image, and compare the loss rates of the first photographed image and the second photographed image to obtain a target starting time.

[0033] In summary, the present application provides a method and system for determining the control time sequence of a linear array camera used for collecting images of defects on the surface of a steel plate. The method comprises the following steps: controlling the linear array camera to be turned on at a first opening time sequence and turned off at a first closing time sequence to obtain a first photographed image of the steel plate; the first opening time sequence is to open the frame frequency first and then open the line frequency, and the first closing time sequence is to close the frame frequency first and then close the line frequency; comparing the first photographed image with the actual surface of the steel plate to obtain a loss rate of the first photographed image; the loss rate is the sum of the frame loss rate and the line loss rate; controlling the linear array camera to be turned on at a second opening time sequence and turned off at the first closing time sequence to obtain a second photographed image of the steel plate; the second opening time sequence is to open the line frequency first and then open the frame frequency; comparing the first photographed image with the actual surface of the steel plate to obtain a loss rate of the second photographed image; comparing the loss rates of the first photographed image and the second photographed image to obtain a target starting time sequence; and the target opening time sequence is the opening time sequence of the linear array camera corresponding to the smaller loss rate.

[0034] The method compares the frame loss rate and the line loss rate of the images corresponding to different opening time sequences of the linear array camera, obtains the opening time sequence corresponding to the images with low frame loss rate and line loss rate, and takes the opening time sequence as the preferred opening time sequence, thereby ensuring the quality of the images collected by the visual system and improving the accuracy of the detection of defects on the steel plate. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 A step flow chart of the method for determining the control time sequence of the linear array camera is provided for the embodiments of the present application.

[0036] Figure 2 A connection schematic diagram of the system for determining the control time sequence of the linear array camera is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0037] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely intended to explain the related application, but not to limit the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for the convenience of description.

[0038] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and embodiments.

[0039] Embodiment 1

[0040] As mentioned in the background, in order to solve the problems in the prior art, the present application provides a method for determining the control timing of a linear array camera used for collecting images of defects on the surface of a steel plate, as shown in Figure 1 The method comprises the following steps:

[0041] S1, controlling the linear array camera to be turned on at a first opening timing and turned off at a first closing timing to obtain a first captured image of the steel plate; the first opening timing is to turn on the frame frequency first and then turn on the line frequency, and the first closing timing is to turn off the frame frequency first and then turn off the line frequency;

[0042] S2, comparing the first captured image with the actual surface of the steel plate to obtain a loss rate of the first captured image; the loss rate is the sum of the frame loss rate and the line loss rate;

[0043] S3, controlling the linear array camera to be turned on at a second opening timing and turned off at the first closing timing to obtain a second captured image of the steel plate; the second opening timing is to turn on the line frequency first and then turn on the frame frequency;

[0044] S4, comparing the first captured image with the actual surface of the steel plate to obtain the loss rate of the second captured image;

[0045] S5, comparing the loss rates of the first captured image and the second captured image to obtain a target starting timing; the target opening timing is the opening timing of the linear array camera corresponding to the smaller loss rate.

[0046] The working principle of the method is as follows: the linear array camera scans the surface of the moving steel plate line by line, and based on the scanning results of several lines, a frame of image is output, and the linear array camera has both the line frequency for controlling the scanning line by line and the frame frequency for controlling the output image. After the linear array camera receives the signal that the steel plate enters the detection area, the linear array camera is turned on. Whether to turn on the line frequency first or the frame frequency first when turned on is related to the quality of the finally collected image. Therefore, by comparing the image loss rates obtained by turning on at two opening timings respectively, the opening timing with the lower loss rate can be determined.

[0047] Comparing the first captured image or the second captured image with the actual surface of the steel plate can obtain the difference between the image of the steel plate defect and the actual steel plate defect through actual verification. The loss rate is the difference degree between the image and the actual surface. The greater the loss rate is, the greater the difference between the image and the actual surface is.

[0048] The method obtains the opening time sequence corresponding to the image with low frame loss rate and line loss rate by comparing the frame loss rate and line loss rate of the images corresponding to different opening time sequences of the linear array camera, and takes the opening time sequence as the preferred opening time sequence, so as to ensure the quality of the image collected by the visual system and improve the accuracy of the steel plate defect detection.

[0049] In a preferred embodiment, the photographed image corresponding to the target starting time sequence is a first target image; after obtaining the target starting time sequence, the following steps are further included:

[0050] The linear array camera is controlled to be turned on at the target opening time sequence and turned off at a second closing time sequence, and a third photographed image of the steel plate is obtained; the second closing time sequence is to close the line frequency first and then close the frame frequency;

[0051] The third photographed image is compared with the actual surface of the steel plate to obtain the loss rate of the third photographed image;

[0052] The frame loss rate of the first target image and the third photographed image is compared to obtain a target closing time sequence, and the target closing time sequence is the closing time sequence of the linear array camera corresponding to the smaller loss rate.

[0053] After the linear array camera receives the signal that the steel plate moves out of the detection area, the linear array camera is turned off, and whether to close the line frequency first or the frame frequency first also relates to the quality of the finally collected image, so based on the preferred opening time sequence obtained, further testing is performed to obtain the image loss rate of the two closing time sequences under the opening time sequence, and the two loss rates are compared to determine the closing time sequence with low loss rate, and then the time sequence combination with the lowest loss rate is obtained in combination with the target opening time sequence, and the time sequence combination is the sequence of which to open first and which to open second at the beginning of collection, and the sequence of which to close first and which to close second at the end of collection.

[0054] In a preferred embodiment, the linear array camera is controlled to be turned on at different opening time sequences, and at least the following steps are included:

[0055] After receiving an entry signal, timing is started, and after the entry signal lasts for a first preset time length, a first control signal is sent, and the first control signal is used to control the linear array camera to be turned on at the corresponding opening time sequence; the entry signal is a signal that the steel plate enters the detection area.

[0056] In a preferred embodiment, the linear array camera is controlled to be turned off at different closing time sequences, and at least the following steps are included:

[0057] After receiving an exit signal, timing is started, and after the exit signal lasts for a second preset time length, a second control signal is sent, and the second control signal is used to control the linear array camera to be turned off at the corresponding closing time sequence; the exit signal is a signal that the steel plate leaves the detection area.

[0058] Specifically, one photoelectric switch is arranged at the entrance and the exit of the image acquisition area of the steel plate, and the photoelectric switch is a mirror reflection type photoelectric switch, which avoids signal failure caused by interference of the field environment. When the photoelectric switch at the entrance senses that the head end of the steel plate enters the acquisition area and the duration is 50 ms, it is determined that the entrance signal of this detection is valid, and at this time, the first control signal is sent, the line array camera and the light source are turned on, image acquisition is started, and 40001 is set to 1 to inform the industrial computer to start storing images.

[0059] The number of photoelectric switches is greater than or equal to 2, and the photoelectric switches can be additionally arranged between the entrance and the exit to divide the whole process into multiple sub-processes for detection. The detection mode of each sub-process is the same as that described in the embodiment, the first preset duration is 50 ms, and the second preset duration is 500 ms.

[0060] The programmable logic controller (PLC) controls the whole detection process. The photoelectric switches are connected to the electric control cabinet through a distribution box. The electric control cabinet is connected to the distribution box through a 6-core shielded wire, of which 2 cores are for the power supply of the photoelectric switch and 4 cores are for the signal of the photoelectric switch. The distribution box is connected to each photoelectric switch through a 3-core shielded wire, of which 2 cores are for the power supply of the photoelectric switch and 1 core is for the signal of the photoelectric switch. The signal of the photoelectric switch at the entrance is the entrance signal, and the signal of the photoelectric switch at the exit is the exit signal.

[0061] The photoelectric switches arranged at the entrance and the exit of the acquisition area can effectively and accurately detect the entering and moving out of the steel plate from the acquisition area, so that the acquisition can be started as soon as the steel plate enters and stopped as soon as the steel plate moves out, thereby reducing the probability of frame loss and line loss.

[0062] In a preferred embodiment, the steel plate moves in a first direction; the line array camera is turned on at a first opening time sequence and turned off at a first closing time sequence to obtain a first photographed image of the steel plate, including at least the following steps:

[0063] After the first control signal is sent, the line array camera is turned on at the first opening time sequence, and the line array camera starts to scan the surface of the steel plate.

[0064] After the second control signal is sent, the line array camera is turned off at the first closing time sequence, and the line array camera stops scanning the surface of the steel plate. Based on the scanning of the line array camera during the whole movement of the steel plate, a first photographed image of the steel plate is obtained.

[0065] In the collection area, a plurality of line array cameras are distributed along the first direction. When the steel plate moves, each line array camera scans the moving steel plate, and the image of the entire surface of the steel plate is obtained.

[0066] In a preferred embodiment, the frame frequency is opened, and at least the following steps are included:

[0067] A high level is set to the frame signal channel of the line array camera.

[0068] In a preferred embodiment, the frame frequency is closed, and at least the following steps are included:

[0069] A low level is set to the frame signal channel of the line array camera.

[0070] In a preferred embodiment, the line frequency is opened, and at least the following steps are included:

[0071] The power switch of the synchronization box is opened, and the synchronization box is powered on.

[0072] In a preferred embodiment, the line frequency is closed, and at least the following steps are included:

[0073] The power switch of the synchronization box is closed, and the synchronization box is powered off.

[0074] Specifically, after receiving the entrance signal and a certain time delay, the synchronization box is turned on through I / O control, at this time the camera is turned on and enters the collection state, and the light source is also turned on. After the encoder is driven, the camera directly collects images.

[0075] After receiving the photoelectric switch exit signal and a certain time delay, the synchronization box is turned off through I / O control, at this time the camera enters the closed state, and the light source is also turned off. The camera stops collecting images.

[0076] Specifically, the first control signal is an encoder input signal, and the encoder input signal is controlled through the synchronization box in an I / O mode. The encoder input signal can be divided into multiple channel signals through the synchronization box and transmitted to multiple cameras (there are multiple line array cameras in the first direction). The I / O control mode can avoid synchronization difference related problems caused by time delay. The number of channels is at least 2.

[0077] The encoder is a heavy load incremental encoder with IP66 protection level, high precision code disc and solid electronic components that can withstand strong impact, vibration and extreme temperature environment.

[0078] Embodiment 2

[0079] The embodiment provides a system for determining the control timing of a linear array camera, which is used for completing the method for determining the control timing of the linear array camera in the embodiment 1. Figure 2 As shown in the figure, the system comprises:

[0080] a control module configured to control the linear array camera to be turned on at a first opening timing and turned off at a first closing timing, and control the linear array camera to be turned on at a second opening timing and turned off at the first closing timing;

[0081] a calculation module configured to compare the first photographed image with the actual surface of the steel plate to obtain a loss rate of the first photographed image, compare the second photographed image with the actual surface of the steel plate to obtain the loss rate of the second photographed image, and compare the loss rates of the first photographed image and the second photographed image to obtain a target starting timing.

[0082] The method for determining the optimal timing when the linear array camera collects images can be completed based on the determining system, the control module of the determining system adjusts the timing after receiving the entry signal and the exit signal, so that the image collected by the linear array camera is obtained, and then the calculation module calculates the loss rate of the photographed image corresponding to each change in timing, so that the timing with a low loss rate can be used as the preferred timing, and the timing determined by the method and the system in the future can reduce the frame loss rate and the line loss rate, ensure the quality of the collected images, and improve the accuracy of the steel plate surface defect detection.

[0083] The principles and implementation manners of the present application are described by using specific examples in the present application, and the above embodiment is only used for helping to understand the method and the core idea of the present application. The above description is only the preferred embodiment of the present application, and it should be pointed out that, due to the limitation of the expression, there are infinite specific structures, and for ordinary skilled persons in the technical field, some improvements, decorations or changes can be made without departing from the principles of the present application, and the above technical features can be combined in an appropriate manner; the improvements, decorations, changes or combinations, or the direct application of the inventive concept and technical scheme to other occasions without improvement, should be regarded as the protection scope of the present application.

Claims

1. A method for determining the control timing of a linear array camera used for collecting images of surface defects of a steel sheet, characterized in that, The method comprises the following steps: controlling the line array camera to be turned on under a first opening timing and turned off under a first closing timing to obtain a first photographed image of the steel plate; the first opening timing is to turn on the frame frequency first and then turn on the line frequency, and the first closing timing is to turn off the frame frequency first and then turn off the line frequency; comparing the first photographed image with the actual surface of the steel plate to obtain a loss rate of the first photographed image; the loss rate is the sum of the frame loss rate and the line loss rate; controlling the line array camera to be turned on under a second opening timing and turned off under the first closing timing to obtain a second photographed image of the steel plate; the second opening timing is to turn on the line frequency first and then turn on the frame frequency; comparing the first photographed image with the actual surface of the steel plate to obtain the loss rate of the second photographed image; comparing the loss rates of the first photographed image and the second photographed image to obtain a target starting timing; the target starting timing is the opening timing of the line array camera corresponding to the smaller loss rate.

2. The method of claim 1, wherein, The photographed image corresponding to the target starting timing is a first target image; after the target starting timing is obtained, the method further comprises the following steps: controlling the line array camera to be turned on under the target starting timing and turned off under a second closing timing to obtain a third photographed image of the steel plate; the second closing timing is to turn off the line frequency first and then turn off the frame frequency; comparing the third photographed image with the actual surface of the steel plate to obtain a loss rate of the third photographed image; comparing the frame loss rates of the first target image and the third photographed image to obtain a target closing timing; the target closing timing is the closing timing of the line array camera corresponding to the smaller loss rate.

3. The method of claim 1, wherein, controlling the line array camera to be turned on under different opening timings, at least comprising the following steps: after receiving an entry signal, starting timing; after the entry signal lasts for a first preset time length, sending a first control signal; the first control signal is used to control the line array camera to be turned on under the corresponding opening timing; the entry signal is a signal that the steel plate enters a detection area.

4. The method of claim 3, wherein, controlling the line array camera to be turned off under different closing timings, at least comprising the following steps: after receiving an exit signal, starting timing; after the exit signal lasts for a second preset time length, sending a second control signal; the second control signal is used to control the line array camera to be turned off under the corresponding closing timing; the exit signal is a signal that the steel plate leaves the detection area.

5. The method of claim 4, wherein, The steel plate moves along a first direction; controlling the line array camera to be turned on under a first opening timing and turned off under a first closing timing to obtain a first photographed image of the steel plate, at least comprising the following steps: after sending the first control signal, the line array camera is turned on under the first opening timing, and the line array camera starts to scan the surface of the steel plate; after sending the second control signal, the line array camera is turned off under the first closing timing, and the line array camera stops scanning the surface of the steel plate; based on the scanning of the line array camera during the entire movement of the steel plate, a first photographed image of the steel plate is obtained.

6. The method of claim 1, wherein, turning on the frame frequency, at least comprising the following steps: placing a high level to a frame signal channel of the line array camera.

7. The method of claim 1, wherein, The closing frame frequency comprises at least the following steps: Setting low level to the frame signal channel of the linear array camera.

8. The method of claim 1, wherein, The opening horizontal frequency comprises at least the following steps: Turning on the power switch of the sync box, and powering on the sync box.

9. The method of claim 1, wherein, The closing horizontal frequency comprises at least the following steps: Turning off the power switch of the sync box, and powering off the sync box.

10. A system for determining control timing of a linear array camera, the system comprising: A determination method for completing the linear array camera control timing as claimed in any one of claims 1-9, the system comprising: A control module configured to control the linear array camera to be turned on at a first opening timing and turned off at a first closing timing, and to control the linear array camera to be turned on at a second opening timing and turned off at the first closing timing; A calculation module configured to compare the first captured image with the actual surface of the steel plate to obtain a missing rate of the first captured image, compare the second captured image with the actual surface of the steel plate to obtain the missing rate of the second captured image, and compare the missing rates of the first captured image and the second captured image to obtain a target starting timing.

Images