Crane double-lifting-point synchronous control method based on machine vision detection

Abstract

The invention discloses a crane double-lifting-point synchronous control method based on machine vision detection, and belongs to the technical field of automatic control. The visual camera captures a clutch position picture, transmits the picture to visual analysis software of the industrial control computer, obtains the clutch position according to a clutch deep learning training algorithm, judges the position state of the synchronizing shaft, and sends real-time state information of the synchronizing shaft to the controller; and the controller compares the real-time state information of the synchronous shaft with the synchronous instruction input setting information in real time, distinguishes the conformity and safety of the synchronous shaft state and the synchronous instruction input setting, and makes a corresponding control strategy. The machine vision technology is adopted to detect the real-time position of the clutch, the separation and kneading states of the synchronizing shaft are judged, the conformity and safety of the state of the synchronizing shaft are intelligently distinguished by combining a system synchronizing instruction input signal, a synchronous control mode is output under the condition that the state of the synchronizing shaft is normal, and normal operation of the system is ensured.

Description

Technical Field

[0001] The invention relates to the field of automation control, and in particular to a crane double-hanging-point synchronous control method based on machine vision detection. Background Art

[0002] Cranes are special equipment. When they are first built, they are often considered to be multi-purpose and to meet the needs of multiple lifting operations, such as single hook operation, electrical synchronous operation and mechanical synchronous operation. Different operation methods are achieved by separating and kneading the synchronous shaft. The traditional separation and kneading of synchronous shafts requires multiple people to disassemble and assemble, which has low operating efficiency, high labor intensity and high operating risks.

[0003] In order to change the above defects, the manual clutch has been introduced in recent years to achieve rapid clutch of the synchronous shaft, making the switching easier, greatly improving the clutch efficiency, reducing the labor intensity of personnel, and reducing the operation risk. However, the manual clutch has no stroke detection device, and there is no interlocking with the control system, so it cannot make intelligent judgments and controls. Once the manual clutch is abnormal, if the control system cannot sense and respond to the shutdown in time, it will cause serious safety consequences.

[0004] The main reasons for manual clutch anomalies are: clutch disengagement without reason and abnormal operation by personnel. The clutch disengages without reason because the synchronous shaft belongs to the high-speed shaft, and the clutch has been in contact with it for a long time, which is affected by both rotational friction and high-frequency resonance. The clutch will slowly loosen and cause the synchronous shaft to disengage. Abnormal operation by personnel is mainly due to the lack of experience and responsibility of the operator, the clutch is not properly operated, and the synchronous shaft is not fully engaged. As the high-speed shaft rotates, the clutch will slowly loosen and cause the synchronous shaft to disengage. Therefore, it is very necessary to study a synchronous control method with real-time state detection of the synchronous shaft, the results are associated with the control system, and dynamic interlocking. Summary of the invention

[0005] The present invention aims to solve the problem in the prior art that the abnormality of the manual clutch leads to the inability to respond to the shutdown in time. A crane double-hanging-point synchronization control method based on machine vision detection is proposed. The machine vision technology is used to detect the real-time position of the clutch, judge the separation and engagement state of the synchronization shaft, and combine the system synchronization command input signal to intelligently identify the compliance and safety of the synchronization shaft state.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows: The method for synchronously controlling double lifting points of a crane based on machine vision detection comprises the following steps: Step a, using the visual analysis software installed in the industrial control computer to perform self-inspection on the visual camera and light source installed near the clutch, and proceed to the next step after the self-inspection is successful; Step b, the visual camera and the light source work simultaneously to capture a photo of the clutch position, and transmit the photo to the industrial control computer vision analysis software; Step c, the visual analysis software obtains the clutch position according to the clutch deep learning training algorithm, and combines the calibration parameters to determine whether the synchronous shaft belongs to a state of separation, kneading, or an abnormal intermediate position, and sends the real-time state information of the synchronous shaft to the controller through the industrial control computer; Step d: After receiving the real-time status information of the synchronous axis, the controller compares it with the synchronous instruction input setting information in real time, identifies the conformity and safety of the synchronous axis status and the synchronous instruction input setting, and makes a corresponding control strategy; Step e: After the controller determines the synchronous command output signal, it generates a frequency converter control word and sends it to the frequency converter. The frequency converter controls the start and stop of the hoisting motor according to different control words to achieve synchronous control of the crane under different operations.

[0007] Furthermore, in step b, a camera is set up in the direction facing the clutch, and the camera imaging plane is ensured to be level with the horizontal plane, and the camera captures an image of the clutch area.

[0008] Furthermore, in step c, the visual analysis software identifies the clutch position through the SIFT algorithm, obtains the minimum enclosing rectangle of the clutch after grayscale conversion, edge detection, and contour screening preprocessing, calculates the inclination angle between the central axis of the rectangle and the horizontal line, and then determines the working state of the clutch based on the angle.

[0009] Furthermore, edge detection is implemented using the Canny algorithm, and the steps include: 1) Perform Gaussian smoothing on the input image to reduce the error rate; 2) Calculate the gradient magnitude and direction to estimate the edge strength and direction at each point; 3) According to the gradient direction, the gradient amplitude is non-maximum suppressed; 4) Use double thresholding to process and connect edges, and save the result into an edge map of the same size and type as the source image.

[0010] Furthermore, after contour filtering, the minAreaRect() function is used to obtain the minimum enclosing rectangle covering the contour. The minimum enclosing rectangle contains three attributes: 1) the center point of the rectangle, that is, the centroid; 2) the side length, including length and width; 3) the angle value; the angle attribute is called to obtain the rotation angle, which is the inclination angle of the central axis of the rectangle to the horizontal line.

[0011] Further, in step d, the synchronous mode knob switch is connected to the controller through a signal cable, and the controller receives an input mode of single hook operation, electrical synchronous operation, and mechanical synchronous operation selected by the synchronous mode knob switch; the hanging point knob switch is connected to the controller through a signal cable, and the controller receives an input mode of hanging point 1 single action, hanging point 2 single action, and double hanging point linkage selected by the hanging point knob switch; When the synchronous mode knob switch input is single hook operation, if the lifting point knob switch input is lifting point 1 single action mode or lifting point 2 single action mode, the synchronous command input on the controller is set to lifting point 1 single action operation or lifting point 2 single action operation accordingly; if the lifting point knob switch is double lifting point linkage mode, the synchronous command input on the controller is set to abnormal operation selection; When the synchronous mode knob switch is in electrical synchronous operation, if the lifting point knob switch is in lifting point 1 single action mode or lifting point 2 single action mode, the synchronous command input on the controller is set to abnormal operation selection; if the lifting point knob switch is in double lifting point linkage mode, the synchronous command input on the controller is set to electrical synchronous operation; When the synchronization mode knob switch is in mechanical synchronization operation, if the suspension point knob switch is in suspension point 1 single-action mode or suspension point 2 single-action mode, the synchronization command input on the controller is set to abnormal operation selection; if the suspension point knob switch is in double suspension point linkage mode, the synchronization command input on the controller is set to mechanical synchronization operation.

[0012] Furthermore, when the real-time status of the synchronous axis is separated, if the controller's synchronous command input is set to single-motion operation of lifting point 1 or single-motion operation of lifting point 2, the corresponding synchronous command output is single-motion operation of lifting point 1 or single-motion operation of lifting point 2; if the controller's synchronous command input is set to electrical synchronization selection, the synchronous command output is electrical synchronization operation; if the controller's synchronous command input is set to mechanical synchronization selection, the synchronous command output is a mode selection fault; if the controller's synchronous command input is set to an operation selection abnormality, the synchronous command output is a mode selection fault.

[0013] Furthermore, when the real-time state of the synchronous axis is kneading, if the controller's synchronous command input is set to single-action operation of lifting point 1 or single-action operation of lifting point 2, the synchronous command output is a mode selection fault; if the controller's synchronous command input is set to electrical synchronous operation, the synchronous command output is a mode selection fault; if the controller's synchronous command input is set to mechanical synchronous operation, the synchronous command output is mechanical synchronous operation; if the controller's synchronous command input is set to operation selection abnormality, the synchronous command output is a mode selection fault.

[0014] Furthermore, when the real-time state of the synchronous shaft is an intermediate abnormal position, if the controller's synchronous instruction input is set to single-action operation of lifting point 1 or single-action operation of lifting point 2, the synchronous instruction output is a synchronous shaft fault; if the controller's synchronous instruction input is set to electrical synchronous operation, the synchronous instruction output is a synchronous shaft fault; if the controller's synchronous instruction input is set to mechanical synchronous operation, the synchronous instruction output is a synchronous shaft fault; if the controller's synchronous instruction input is set to mode selection abnormality, the synchronous instruction output is a synchronous shaft fault.

[0015] Furthermore, in step e, when the controller synchronization instruction output is single-action operation of lifting point 1 or lifting point 2, the controller controls the frequency converter of the corresponding lifting point to connect to the corresponding lifting motor to realize the operation or stop control of the lifting motor of the lifting point; When the controller synchronization instruction output is electrical synchronous operation, the controller controls the inverters of the two lifting points to connect to the corresponding lifting motors to realize the operation control of the lifting motors of the two lifting points. The controller obtains the position difference between the lifting point 1 and the lifting point 2 in real time through the position sensor, and compares the speed synchronization of the lifting point 1 and the lifting point 2. Through program logic judgment, the lifting point operation speed is adjusted to realize the electrical synchronous operation of the double lifting point lifting mechanism. When the controller synchronization command output is mechanical synchronous operation, the controller controls the operation of the lifting motor at lifting point 1, and the frequency converter at lifting point 1 and the frequency converter at lifting point 2 form a master-slave torque control internally. The frequency converter at lifting point 1 sends the real-time torque value to the frequency converter at lifting point 2 through the signal cable, and the frequency converter at lifting point 2 outputs the same torque signal and connects to the lifting motor at lifting point 2 through the power cable, thereby realizing the mechanical synchronous control of the double lifting point lifting mechanism; When the controller synchronization command output is a synchronization axis fault or a mode selection fault, the controller controls the hoisting motors of the lifting point 1 and the lifting point 2 to stop running.

[0016] In summary, the present invention has the following advantages: 1. The present invention uses machine vision technology to detect the real-time position of the clutch and judge the separation and engagement state of the synchronous shaft. Combined with the system synchronization command input signal, the conformity and safety of the synchronous shaft state are intelligently identified. When the synchronous shaft state is normal, the synchronous control mode is output, and the system can operate normally; when the synchronous shaft state is abnormal, the synchronous shaft fault and shutdown command are output, and the system stops running immediately, thereby effectively avoiding the operation safety risks caused by the abnormal synchronous shaft state; 2. The present invention combines the SIFT algorithm to identify the clutch position, and then combines grayscale conversion, edge detection, contour screening and other preprocessing methods to obtain the minimum enclosing rectangle and tilt angle of the clutch. The tilt angle is combined with calibration parameters to determine the working state of the clutch, and a more accurate state judgment result can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall layout of the visual inspection system of the present invention; Figure 2 A technical roadmap for the method of the present invention; Figure 3 A schematic diagram of the inclination angle of the clutch of the present invention; In the figure: 1. Visual camera; 2. Light source; 3. Bracket; 4. Clutch; 5. Synchronous shaft; 6. Lifting motor. DETAILED DESCRIPTION

[0018] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments and drawings. It should be understood by those skilled in the art that the content described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0019] The present invention provides a crane double lifting point synchronization control method based on machine vision detection, referring to Figure 2 The technical route shown includes the following steps: Step a, the system is powered on, and the visual analysis software installed in the industrial control computer performs a self-check on the visual camera and light source. After the self-check is successful, the next step is carried out. If the self-check fails, the industrial control computer sends a fault to the controller (PLC), and the controller (PLC) control system stops running.

[0020] like Figure 1 The figure shows the overall layout diagram of the visual inspection system, which includes the synchronous shaft, clutch, visual camera, light source, bracket, signal cable, power cable, industrial control computer, controller (PLC), synchronous mode knob switch, hanging point knob switch, inverter, lifting motor, position sensor, etc.

[0021] Among them, the visual camera and the light source are installed on the bracket, the bracket is welded near the clutch, the light source is connected to the visual camera through a signal cable, the visual camera is connected to the industrial control computer through a signal cable, the industrial computer is connected to the controller (PLC) through a signal cable, the controller (PLC) is connected to the inverter through a signal cable, the inverter is connected to the lifting motor through a power cable, the synchronous mode knob switch is connected to the controller (PLC) through a signal cable, the hanging point knob switch is connected to the controller (PLC) through a signal cable, the hanging point 1 inverter is connected to the hanging point 2 inverter through a signal cable, and the height sensor is installed on the lifting mechanism equipment and connected to the controller (PLC) through a signal cable.

[0022] Step b: The visual camera and the light source work simultaneously to capture a photo of the clutch position, and transmit the photo to the industrial control computer vision analysis software through a signal cable.

[0023] In this step, the camera is set up in the direction facing the clutch, and the camera imaging plane is ensured to be level with the horizontal plane, and the camera captures the clutch area image.

[0024] Step c: The visual analysis software calculates the clutch position according to the clutch deep learning training algorithm, and combines the calibration parameters to determine whether the synchronous shaft is in a state of separation, engagement, or an abnormal intermediate position. The industrial control computer sends the real-time status information of the synchronous shaft to the controller (PLC) via a signal cable.

[0025] In this embodiment, the visual analysis software uses the SIFT algorithm to identify the clutch position, and obtains the minimum enclosing rectangle of the clutch after preprocessing such as grayscale conversion, edge detection, and contour screening. The inclination angle between the central axis of the rectangle and the horizontal line is calculated, such as Figure 3 As shown, the clutch working state is determined based on the angle combined with the calibration parameters.

[0026] SIFT (Scale Invariant Feature Transform) is an efficient area detection algorithm that can be applied to object recognition, robot map perception and navigation, image stitching, 3D model building, gesture recognition, image tracking and motion comparison. It has the advantages of stability, uniqueness, large volume, high speed and scalability. It can solve the problems caused by target rotation, scaling, translation, image radiation / projection transformation, and can still achieve good detection results under the influence of lighting, partial target occlusion, and clutter and noise scenes. The SIFT algorithm can be decomposed into the following steps: 1) Scale space extrema detection: Search for image locations at all scales. Use Gaussian derivative functions to identify potential scale and rotation invariant interest points.

[0027] 2) Accurate positioning of key points: At each candidate location, a fine-tuned model is used to determine the position and scale. The key points are selected based on their stability.

[0028] 3) Determine the main direction of the key point: Based on the local gradient direction of the image, one or more directions are assigned to each key point position. All subsequent operations on the image data are transformed relative to the direction, scale and position of the key point, thereby providing invariance to these transformations.

[0029] 4) Generate SIFT feature vectors (descriptors of key points): In the neighborhood around each key point, the local gradients of the image are measured at a selected scale. These gradients are transformed into a representation that allows for relatively large local shape deformations and lighting changes.

[0030] A feature matrix is ​​generated by extracting feature points with scale-invariant feature transformation in the clutch image. A classification model including clutch area and non-clutch area obtained by pre-training is called, and the classification model is obtained based on feature points of scale-invariant feature transformation of multiple clutch areas and multiple non-clutch areas. The clutch position can be determined according to the feature point matrix using the classification model.

[0031] Edge detection mainly detects pixels with dramatic changes in brightness (i.e., large gradient changes) in digital images through some means, and is biased towards changes in pixels in the image. The results are usually saved in an edge map of the same size and type as the source image. In this embodiment, Canny edge detection is used. The Canny algorithm proposes non-maximum suppression based on the edge gradient direction and double-threshold hysteresis threshold processing. In this embodiment, the processing steps of the Canny algorithm are as follows: 1) Perform Gaussian smoothing on the input image to reduce the error rate; 2) Calculate the gradient magnitude and direction to estimate the edge strength and direction at each point; 3) According to the gradient direction, the gradient amplitude is non-maximum suppressed; 4) Use double thresholding to process and connect edges.

[0032] The contour can be simply considered as a curve connecting consecutive points (connected to the boundary) with the same color or grayscale. The contour is the external feature of the image target, which is very important for deeper processing such as image analysis, target recognition and understanding.

[0033] Contour detection refers to detecting the boundaries of objects in an image, and tends to focus on upper-level semantic objects. For example, the findContours() function in OpenCV will get each contour and store it as a point vector. In addition, it also gets the topological information of an image, that is, the index number of the next contour, the previous contour, etc. of a contour.

[0034] The basic principle of contour extraction is: for a binary image with a black background and a white target, if a white point is found in the image and its 8-neighborhood (or 4-neighborhood) is also white, it means that the point is an internal point of the target and is set to black, which visually looks like the inside is hollowed out; otherwise, it remains white and the point is the contour point of the target. Generally, before finding the contour, the image must be thresholded or Canny edge detected to convert it into a binary image.

[0035] Minimum enclosing rectangle and rotation angle: After obtaining the object outline, the minAreaRect() function can be used to obtain the minimum enclosing rectangle covering the outline. The obtained RotatedRect has three properties: 1) the center point (center of mass) of the rectangle; 2) the length of the side (length and width); 3) the rotation angle (the returned value is the angle value rather than the radian value). The rotation angle can be obtained by calling the angle property, and the working state of the clutch can be determined based on the angle.

[0036] The present invention can accurately identify the clutch position on the image through the SIFT algorithm and classification model. At the same time, combined with preprocessing methods such as grayscale conversion, edge detection, and contour screening, the minimum enclosing rectangle and inclination angle of the clutch can be obtained. The working state of the clutch can be judged according to the inclination angle combined with calibration parameters, and a more accurate judgment result can be obtained.

[0037] Step d: After receiving the real-time status information of the synchronous axis transmitted from the industrial control computer via the signal cable, the controller (PLC) performs a real-time comparison with the synchronous instruction input setting information to identify the conformity and safety of the synchronous axis status and the synchronous instruction input setting, and makes a corresponding control strategy.

[0038] Specifically, in this step, when the real-time state of the synchronous axis is separated, and the controller (PLC) synchronous command input is set to the single-action operation of the lifting point 1, the synchronous command output is the single-action operation of the lifting point 1; When the real-time status of the synchronous axis is separated, and the controller (PLC) synchronous command input is set to single-action operation of lifting point 2, the synchronous command output is single-action operation of lifting point 2; When the real-time status of the synchronous axis is separated and the controller (PLC) synchronous command input is set to electrical synchronization selection, the synchronous command output is electrical synchronous operation; When the real-time status of the synchronous axis is separated and the controller (PLC) synchronous command input is set to mechanical synchronization selection, the synchronous command output is a mode selection fault; When the real-time status of the synchronous axis is separated and the controller (PLC) synchronous instruction input is set to abnormal job selection, the synchronous instruction output is a mode selection fault.

[0039] When the real-time state of the synchronous axis is kneading, and the synchronous command input of the controller (PLC) is set to single-action operation of lifting point 1, the synchronous command output is a mode selection fault; When the real-time state of the synchronous axis is kneading, and the synchronous command input of the controller (PLC) is set to single-action operation of lifting point 2, the synchronous command output is a mode selection fault; When the real-time state of the synchronous axis is kneading, and the controller (PLC) synchronous command input is set to electrical synchronous operation, the synchronous command output is a mode selection fault; When the real-time state of the synchronous axis is kneading, and the controller (PLC) synchronization command input is set to mechanical synchronous operation, the synchronization command output is mechanical synchronous operation; When the real-time state of the synchronous axis is kneading and the controller (PLC) synchronous instruction input is set to abnormal job selection, the synchronous instruction output is a mode selection fault.

[0040] When the real-time status of the synchronous axis is the middle abnormal position and the synchronous instruction input of the controller (PLC) is set to the single-action operation of the lifting point 1, the synchronous instruction output is the synchronous axis fault; When the real-time status of the synchronous axis is the middle abnormal position and the synchronous command input of the controller (PLC) is set to the single-action operation of the lifting point 2, the synchronous command output is the synchronous axis fault; When the real-time status of the synchronous axis is the middle abnormal position and the controller (PLC) synchronous command input is set to electrical synchronous operation, the synchronous command output is a synchronous axis fault; When the real-time status of the synchronous axis is the middle abnormal position and the controller (PLC) synchronous command input is set to mechanical synchronous operation, the synchronous command output is a synchronous axis fault; When the real-time status of the synchronous axis is the middle abnormal position and the controller (PLC) synchronous instruction input is set to the mode selection abnormality, the synchronous instruction output is a synchronous axis fault.

[0041] Step e: After the controller (PLC) determines the synchronous command output signal, it generates the inverter control word and sends it to the inverter through the signal cable. The inverter controls the start and stop of the hoisting motor according to different control words to achieve synchronous control of the crane under different operations: When the controller (PLC) synchronous instruction output is single-action operation of lifting point 1, the controller (PLC) generates the operation control word of the lifting point 1 inverter, sends it to the lifting point 1 inverter through the signal cable, and the inverter outputs the operation frequency according to the operation control word, and connects to the lifting motor of lifting point 1 through the power cable to realize the operation control of the lifting motor of lifting point 1.

[0042] The controller (PLC) generates the stop control word of the frequency converter of the lifting point 2, and sends it to the frequency converter of the lifting point 2 through the signal cable. The frequency converter sets the output frequency to zero according to the stop control word, and connects to the lifting motor of the lifting point 2 through the power cable to realize the stop control of the lifting motor of the lifting point 2. In this way, the single-action operation of the lifting point 1 is realized.

[0043] When the controller (PLC) synchronous command output is single-action operation of suspension point 2, the controller (PLC) generates the operation control word of the suspension point 2 inverter, which is sent to the suspension point 2 inverter through the signal cable. The inverter outputs the operation frequency according to the operation control word, and connects to the lifting motor of suspension point 2 through the power cable to realize the operation control of the lifting motor of suspension point 2. The controller (PLC) generates the stop control word of the suspension point 1 inverter, which is sent to the suspension point 1 inverter through the signal cable. The inverter sets the output frequency to zero according to the stop control word, and connects to the lifting motor of suspension point 1 through the power cable to realize the stop control of the lifting motor of suspension point 1. In this way, single-action operation of suspension point 2 is realized.

[0044] When the controller (PLC) synchronous command output is electrical synchronous operation, the controller (PLC) generates the inverter operation control word for suspension point 1, and sends it to the inverter for suspension point 1 through the signal cable. The inverter outputs the operation frequency according to the operation control word, and connects to the lifting motor of suspension point 1 through the power cable to realize the operation control of the lifting motor of suspension point 1. The controller (PLC) generates the inverter operation control word for suspension point 2, and sends it to the inverter for suspension point 2 through the signal cable. The inverter outputs the operation frequency according to the operation control word, and connects to the lifting motor of suspension point 2 through the power cable to realize the operation control of the lifting motor of suspension point 2. Position sensors are installed on the lifting point 1 and the lifting point 2. The controller (PLC) calculates the position difference between the lifting point 1 and the lifting point 2 in real time, and compares the speed synchronization of the lifting point 1 and the lifting point 2. Through program logic judgment, when the lifting point 1 runs slowly or the lifting point 2 runs fast, the controller (PLC) appropriately increases the output frequency of the inverter at the lifting point 1 or appropriately reduces the output frequency of the inverter at the lifting point 2. When the lifting point 1 runs fast or the lifting point 2 runs slow, the controller (PLC) appropriately reduces the output frequency of the inverter at the lifting point 1 or appropriately increases the output frequency of the inverter at the lifting point 2. When the position difference between the lifting point 1 and the lifting point 2 is not large, the output frequency of the inverter at the lifting point 1 and the output frequency of the inverter at the lifting point 2 are not adjusted. In this way, the electrical synchronous operation of the double-lifting-point lifting mechanism is realized.

[0045] When the controller (PLC) synchronous command output is mechanical synchronous operation, the controller (PLC) generates the operation control word of the frequency converter of suspension point 1, and sends it to the frequency converter of suspension point 1 through the signal cable. The frequency converter outputs the operation frequency according to the operation control word, and connects to the lifting motor of suspension point 1 through the power cable to realize the operation control of the lifting motor of suspension point 1. The frequency converter of suspension point 1 and the frequency converter of suspension point 2 form the master-slave torque control internally. The frequency converter of suspension point 1 is connected to the frequency converter of suspension point 2 through the signal cable. The frequency converter of suspension point 1 sends the real-time torque value to the frequency converter of suspension point 2. The frequency converter of suspension point 2 outputs the same torque signal and connects to the lifting motor of suspension point 2 through the power cable, so as to realize the mechanical synchronous control of the double suspension point lifting mechanism.

[0046] When the controller (PLC) synchronous command output is a mode selection fault, the controller (PLC) generates a stop control word for the frequency converter of suspension point 1, and sends it to the frequency converter of suspension point 1 through the signal cable. The frequency converter sets the output frequency to zero according to the stop control word, and connects to the lifting motor of suspension point 1 through the power cable to achieve the stop control of the lifting motor of suspension point 1. The controller (PLC) generates a stop control word for the frequency converter of suspension point 2, and sends it to the frequency converter of suspension point 2 through the signal cable. The frequency converter sets the output frequency to zero according to the stop control word, and connects to the lifting motor of suspension point 2 through the power cable to achieve the stop control of the lifting motor of suspension point 2.

[0047] When the controller (PLC) synchronization command output is a synchronous axis fault, the controller (PLC) generates a stop control word for the frequency converter of suspension point 1, and sends it to the frequency converter of suspension point 1 through the signal cable. The frequency converter sets the output frequency to zero according to the stop control word, and connects to the lifting motor of suspension point 1 through the power cable to achieve the stop control of the lifting motor of suspension point 1. The controller (PLC) generates a stop control word for the frequency converter of suspension point 2, and sends it to the frequency converter of suspension point 2 through the signal cable. The frequency converter sets the output frequency to zero according to the stop control word, and connects to the lifting motor of suspension point 2 through the power cable to achieve the stop control of the lifting motor of suspension point 2.

[0048] The present invention adopts machine vision technology to detect the real-time position of the clutch, judge the separation and engagement state of the synchronous shaft, and intelligently distinguishes the compliance and safety of the synchronous shaft state in combination with the system synchronization command input signal. When the synchronous shaft state is normal, the synchronous control mode is output so that the system can operate normally; when the synchronous shaft state is abnormal, the synchronous shaft fault and shutdown command are output, and the system stops running immediately, thereby effectively avoiding the operation safety risks caused by the abnormal synchronous shaft state.

[0049] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A crane double lifting point synchronization control method based on machine vision detection, characterized in that: The steps include: Step a, using the visual analysis software installed in the industrial control computer to perform self-inspection on the visual camera and light source installed near the clutch, and proceed to the next step after the self-inspection is successful; Step b, the visual camera and the light source work simultaneously to capture a photo of the clutch position, and transmit the photo to the industrial control computer vision analysis software; Step c, the visual analysis software obtains the clutch position according to the clutch deep learning training algorithm, and combines the calibration parameters to determine whether the synchronous shaft belongs to a state of separation, kneading, or an abnormal intermediate position, and sends the real-time state information of the synchronous shaft to the controller through the industrial control computer; Step d: After receiving the real-time status information of the synchronous axis, the controller compares it with the synchronous instruction input setting information in real time, identifies the conformity and safety of the synchronous axis status and the synchronous instruction input setting, and makes a corresponding control strategy; Step e: After the controller determines the synchronous command output signal, it generates a frequency converter control word and sends it to the frequency converter. The frequency converter controls the start and stop of the hoisting motor according to different control words to achieve synchronous control of the crane under different operations.

2. The method for synchronous control of double lifting points of a crane based on machine vision detection according to claim 1, characterized in that: In step b, a camera is set up in the direction facing the clutch, and the camera imaging plane is ensured to be level with the horizontal plane, and the camera captures an image of the clutch area.

3. The method for synchronous control of double lifting points of a crane based on machine vision detection according to claim 1, characterized in that: In step c, the visual analysis software uses the SIFT algorithm to identify the clutch position, and obtains the minimum enclosing rectangle of the clutch after grayscale conversion, edge detection, and contour screening preprocessing. The inclination angle between the central axis of the rectangle and the horizontal line is calculated, and the clutch working status is then judged based on the angle.

4. The method for synchronous control of double lifting points of a crane based on machine vision detection according to claim 3, characterized in that: Edge detection is implemented using the Canny algorithm, and the steps include: 1) Perform Gaussian smoothing on the input image to reduce the error rate; 2) Calculate the gradient magnitude and direction to estimate the edge strength and direction at each point; 3) According to the gradient direction, the gradient amplitude is non-maximum suppressed; 4) Use double thresholding to process and connect edges, and save the result into an edge map of the same size and type as the source image.

5. The method for synchronous control of double lifting points of a crane based on machine vision detection according to claim 3, characterized in that: After contour filtering, the minAreaRect() function is used to get the minimum enclosing rectangle covering the contour. The minimum enclosing rectangle contains three properties: 1) the center point of the rectangle, that is, the centroid; 2) the side length, including length and width; 3) the angle value; the angle property is called to get the rotation angle, which is the inclination angle of the central axis of the rectangle to the horizontal line.

6. The method for synchronous control of double lifting points of a crane based on machine vision detection according to claim 1, characterized in that: In step d, the synchronous mode knob switch is connected to the controller through a signal cable, and the controller receives an input mode selected by the synchronous mode knob switch, among single hook operation, electrical synchronous operation, and mechanical synchronous operation; the hanging point knob switch is connected to the controller through a signal cable, and the controller receives an input mode selected by the hanging point knob switch, among hanging point 1 single action, hanging point 2 single action, and double hanging point linkage; When the synchronous mode knob switch input is single hook operation, if the lifting point knob switch input is lifting point 1 single action mode or lifting point 2 single action mode, the synchronous command input on the controller is set to lifting point 1 single action operation or lifting point 2 single action operation accordingly; if the lifting point knob switch is double lifting point linkage mode, the synchronous command input on the controller is set to abnormal operation selection; When the synchronous mode knob switch is in electrical synchronous operation, if the lifting point knob switch is in lifting point 1 single action mode or lifting point 2 single action mode, the synchronous command input on the controller is set to abnormal operation selection; if the lifting point knob switch is in double lifting point linkage mode, the synchronous command input on the controller is set to electrical synchronous operation; When the synchronization mode knob switch is in mechanical synchronization operation, if the suspension point knob switch is in suspension point 1 single-action mode or suspension point 2 single-action mode, the synchronization command input on the controller is set to abnormal operation selection; if the suspension point knob switch is in double suspension point linkage mode, the synchronization command input on the controller is set to mechanical synchronization operation.

7. The method for synchronously controlling double lifting points of a crane based on machine vision detection according to claim 6, characterized in that: When the real-time status of the synchronous axis is separated, if the controller synchronization command input is set to single-motion operation of lifting point 1 or single-motion operation of lifting point 2, the corresponding synchronization command output is single-motion operation of lifting point 1 or single-motion operation of lifting point 2; if the controller synchronization command input is set to electrical synchronization selection, the synchronization command output is electrical synchronization operation; if the controller synchronization command input is set to mechanical synchronization selection, the synchronization command output is mode selection fault; if the controller synchronization command input is set to operation selection abnormality, the synchronization command output is mode selection fault.

8. The method for synchronously controlling double lifting points of a crane based on machine vision detection according to claim 7, characterized in that: When the real-time state of the synchronous axis is kneading, if the controller's synchronous command input is set to single-action operation of lifting point 1 or single-action operation of lifting point 2, the synchronous command output is a mode selection fault; if the controller's synchronous command input is set to electrical synchronous operation, the synchronous command output is a mode selection fault; if the controller's synchronous command input is set to mechanical synchronous operation, the synchronous command output is mechanical synchronous operation; if the controller's synchronous command input is set to operation selection abnormality, the synchronous command output is a mode selection fault.

9. The method for synchronous control of double lifting points of a crane based on machine vision detection according to claim 8, characterized in that: When the real-time status of the synchronous axis is the middle abnormal position, if the controller synchronous command input is set to single-action operation of lifting point 1 or single-action operation of lifting point 2, the synchronous command output is a synchronous axis fault. If the controller synchronous command input is set to electrical synchronous operation, the synchronous command output is a synchronous axis fault. If the controller synchronous command input is set to mechanical synchronous operation, the synchronous command output is a synchronous axis fault. If the controller synchronous command input is set to mode selection abnormality, the synchronous command output is a synchronous axis fault.

10. The method for synchronously controlling double lifting points of a crane based on machine vision detection according to claim 9, characterized in that: In step e, when the controller synchronization instruction output is single-action operation of lifting point 1 or lifting point 2, the controller controls the frequency converter of the corresponding lifting point to connect to the corresponding lifting motor to realize the operation or stop control of the lifting motor of the lifting point; When the controller synchronization instruction output is electrical synchronous operation, the controller controls the inverters of the two lifting points to connect to the corresponding lifting motors to realize the operation control of the lifting motors of the two lifting points. The controller obtains the position difference between the lifting point 1 and the lifting point 2 in real time through the position sensor, and compares the speed synchronization of the lifting point 1 and the lifting point 2. Through program logic judgment, the lifting point operation speed is adjusted to realize the electrical synchronous operation of the double lifting point lifting mechanism. When the controller synchronization command output is mechanical synchronous operation, the controller controls the operation of the lifting motor at lifting point 1, and the frequency converter at lifting point 1 and the frequency converter at lifting point 2 form a master-slave torque control internally. The frequency converter at lifting point 1 sends the real-time torque value to the frequency converter at lifting point 2 through the signal cable, and the frequency converter at lifting point 2 outputs the same torque signal and connects to the lifting motor at lifting point 2 through the power cable, thereby realizing the mechanical synchronous control of the double lifting point lifting mechanism; When the controller synchronization command output is a synchronization axis fault or a mode selection fault, the controller controls the hoisting motors of the lifting point 1 and the lifting point 2 to stop running.

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