Online measurement method and detection device for dial angle of stepping rotary three-dimensional braiding machine

Abstract

The present invention discloses an online measurement method and detection device for the dial deflection of a step-by-step rotary three-dimensional knitting machine, comprising the following steps: calibrating a binocular vision system, moving the binocular vision system to the side of a specified column of dials through a detection device to collect dial images and identify image feature points, solving the spatial coordinates of the feature points, calculating the deflection angles of all dials in the specified column, then moving the binocular vision system to the next column of dials and performing the deflection measurement step, repeating this process until all dial deflection angles are detected, and then feeding back the measured deflection information of each dial to the equipment control center to correct the dial angle position. The present invention can monitor the deflection angle of the dial online and implement dial angle position feedback control, which can replace the traditional time-consuming and labor-intensive manual dial angle reset method and effectively ensure the smooth operation of the step-by-step rotary three-dimensional knitting machine.

Description

Technical Field

[0001] The present invention relates to the field of visual inspection-assisted three-dimensional braiding machine weaving, and in particular to an online measurement method and a detection device for a dial angle of a step-by-step rotary three-dimensional braiding machine. Background Art

[0002] Compared with traditional two-dimensional structural composite materials, three-dimensional woven composite materials are interwoven in space in the thickness direction to form an overall structure. They have the advantages of good structural integrity, strong impact resistance, and good interlayer performance. They are widely used in many industries such as rail transportation, aerospace, national defense and military industry.

[0003] As the reinforcement of three-dimensional braided composites, the three-dimensional braided preform mainly determines the mechanical properties of its components. The three-dimensional braided fabric is woven in an integrated manner by a three-dimensional braiding machine. Currently, there are various types of weaving machines with different characteristics. Among them, the stepping rotary three-dimensional braiding machine can control the start and stop of the dial to move the yarn carrier to any dial on the machine chassis, thereby realizing digital control of the yarn carrier trajectory. At the same time, yarn carriers can be installed at both ends of the dial. After one action of the dial, an interweaving can be generated, thereby achieving a denser fabric surface. Based on the above technical advantages, the stepping rotary three-dimensional braiding machine has received great attention in the industry.

[0004] The dial of a step-by-step rotary three-dimensional braiding machine is the core moving component, used to shift the position of the yarn carrier during the weaving process. After reciprocating rotation, the dial is prone to deviate from the set angle. When the deviation angle increases to a certain extent, the mechanical structure will interfere and cause the motor to overload. Currently, manual observation of the dial deviation angle is mostly relied upon. Once a large deviation angle is found, the machine is shut down and manually reset. This process is time-consuming and labor-intensive. An automated dial deviation angle detection and reset method and device are urgently needed to solve this technical problem. Summary of the Invention

[0005] Purpose of the invention: In order to solve the problems existing in the prior art, the present invention provides an online measurement method and detection device for the deflection angle of the dial of a step-by-step rotary three-dimensional knitting machine.

[0006] Technical solution: An online measurement method for the deflection angle of a step-by-step rotary three-dimensional braiding machine dial includes the following steps:

[0007] Step 1: Calibrate the binocular vision system to obtain the internal and external parameters of the binocular vision system. The binocular vision system includes a binocular camera.

[0008] Step 2: Move the binocular camera to the side of a row of dials to be inspected, and capture images with both cameras simultaneously.

[0009] Step 3: Use feature detection algorithm to extract the feature endpoints of the dial in the image and calculate the world coordinates of the feature endpoints;

[0010] Step 4: Calculate the slope of the straight line fitted by two adjacent feature endpoints, then calculate the deflection angle value and save it;

[0011] Step 5: Repeat the above steps until the deflection angle of each dial column is measured;

[0012] Step 6: Feedback all deflection values ​​to the control center to correct the deflection.

[0013] Preferably, the world coordinate system in step one changes during the movement of the binocular vision system; the world coordinate system is a Cartesian coordinate system established with a vertex of the machine chassis of the stepping rotary three-dimensional braiding machine close to the binocular vision system as the origin, and the X, Y, and Z axes of the coordinate system are all vectors parallel to the three edges of the machine chassis of the stepping rotary three-dimensional braiding machine, and the XY plane is parallel to the machine chassis of the stepping rotary three-dimensional braiding machine.

[0014] Preferably, two symmetrically distributed circular light sources are embedded on the center line of the dial in step three to form a high pixel value circular area after the image is binarized, and the center of the high pixel value circular area is used as the characteristic endpoint of the dial.

[0015] Preferably, the slope and deflection angle in step 4 are calculated as follows:

[0016] When |x w1 -x w2 |<|z w1 -z w2 |, then θ=0;

[0017] otherwise |θ|=arctan(K);

[0018] (x w1 ,y w1 , z w1 )、(x w2 ,y w2 , z w2 ) are the world coordinates of the two adjacent feature endpoints of the same dial, K is the slope of the two adjacent feature endpoints of the same dial on the XY plane of the world coordinate system, and |θ| is the deflection angle of the dial.

[0019] Preferably, the control center correction method in step 5 is: When the control dial in the center is turned counterclockwise |θ|, Turn the center control dial clockwise |θ|.

[0020] Preferably, a step-by-step rotary three-dimensional braiding machine dial angle detection device comprises a track and a track trolley; the track trolley comprises a binocular camera, a mounting plate, two support frames mounted on a mounting surface of the mounting plate, a camera mounting frame embedded between the two support frames, a guide wheel mounted on the other surface of the mounting plate, a driving wheel, a displacement drive motor, an angle drive motor, and a gear system; the binocular camera is fixed on the camera mounting frame, and an exposure source is installed between the binocular cameras; the gear shaft of the input end gear in the gear system is mounted on the support frame, and the gear shaft of the output end gear in the gear system is fixed on the camera mounting frame, and the angle drive motor is fixed to the outside of the support frame, and the angle drive motor drives the input end gear to rotate and drives the output end gear to rotate, thereby realizing a change in the angular position of the camera mounting frame; the displacement drive motor and the drive wheel are mounted on the mounting plate, the drive wheel is close to the track, and the displacement drive motor drives the drive wheel to rotate, thereby driving the trolley to move along the track.

[0021] Preferably, the two support brackets are symmetrically fixed on a certain mounting surface of the mounting plate by fasteners, and the camera mounting bracket is embedded in the middle of the two support brackets through the two side structures to form a rotating pair.

[0022] Preferably, the guide wheel fits tightly against the track.

[0023] Preferably, a power supply is installed on the mounting plate as a movable power supply.

[0024] Preferably, the tracks are distributed around the chassis of the step-by-step rotary three-dimensional braiding machine and the track level should be lower than the height of the knots formed by the interweaving of the yarns.

[0025] Beneficial effect: The online measurement method and detection device of the dial angle of a step-by-step rotary three-dimensional weaving machine based on binocular vision proposed in the present invention provide a new method and new device for real-time detection of the dial angle. The method in which a track trolley equipped with a binocular camera moves on tracks distributed on the side of the machine chassis and continuously collects images can detect the dial angle in the field of view in real time while avoiding the interference of yarn on visual detection, and correct the dial angle, thereby realizing efficient automatic detection of the dial angle and closed-loop control of the angle position, which can effectively solve the situation in which traditional dial angle correction relies entirely on manual labor, which is time-consuming and labor-intensive, greatly reducing equipment downtime and maintenance time, and improving weaving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of the online measurement method for the dial deflection angle of a step-by-step rotary three-dimensional braiding machine of the present invention;

[0027] Figure 2This is a schematic structural diagram of the machine chassis of the step-by-step rotary three-dimensional knitting machine and the dial angle detection device distributed on the side of the machine chassis;

[0028] Figure 3 Schematic diagram of the structure of the dial angle detection device used in the present invention;

[0029] Figure 4 Schematic diagram of the structure of the image acquisition device used in the present invention;

[0030] Figure 5 Schematic diagram of the binocular camera rotation process used in the present invention;

[0031] Figure 6 Schematic diagram of the movement process of the image acquisition device used in the present invention;

[0032] Figure 7 Schematic diagram of the coordinate system established in the present invention;

[0033] Figure 8 Schematic diagram of the dial and the measured deflection angle used in the present invention;

[0034] Figure 9 Schematic diagram of the dial deflection correction process used in the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0036] Aiming at the problems of low weaving efficiency and high cost caused by the traditional step-by-step rotary three-dimensional braiding machine dial angle completely relying on manual correction after the equipment is stopped, the present invention provides a step-by-step rotary three-dimensional braiding machine dial angle online measurement method and detection device based on binocular vision, such as Figure 1 , specifically including the following steps:

[0037] (1) See Figure 2 A Cartesian world coordinate system is established on the machine chassis 15 of the stepping rotary 3D knitting machine with a vertex close to the detection device as the origin. The X, Y, and Z axes of the coordinate system are all vectors parallel to the three edges of the machine chassis 15, and the XY plane is parallel to the machine chassis 15. Two symmetrically distributed circular light sources 13 are embedded on the center line of the dial 13 on the machine chassis 15 to form a high-pixel value circular area after the image is binarized, facilitating subsequent feature recognition of the image. The center of the circular area is used as the feature endpoint of the dial 13. The binocular camera 2 is calibrated using the calibration model to obtain the internal and external parameters of the binocular vision system.

[0038] (2) See Figure 2 and Figure 3The dial angle detection device of the present invention includes a track 1 and a track trolley. The track trolley includes: a binocular camera 2, a guide wheel 3, a mounting plate 4, a driving wheel 5, a power supply 6, a camera mounting frame 7, a support frame 8, an exposure source 9, a displacement drive motor 10, an angle drive motor 11, and a gear system 12. The track 1 is distributed around the machine chassis 15. The two support frames 8 are symmetrically fixed on a certain mounting surface of the mounting plate 4 by fasteners. The camera mounting frame 7 is embedded in the middle of the two support frames 8 through the two side structures to form a rotating pair. The gear shaft at the input end of the gear system 12 is installed on the support frame 8 and can rotate freely around the central axis. The gear shaft at the output end is fixed on the camera mounting frame 7. The angle drive motor 11 is fixed to the outside of the support frame 8 by fasteners and can drive the gear. The input end gear of the system 12 rotates, thereby driving the output end gear to rotate, thereby realizing the adjustment of the angle position of the camera mounting frame 7. The binocular camera 2 is fixed to the camera mounting frame 7 by fasteners, and an exposure source 9 is installed between the two cameras. The guide wheel 3 is installed on the other mounting surface of the mounting plate 4. Its mounting size can make the guide wheel 3 fit tightly on the track 1, ensuring that the trolley always moves along the track 1. The displacement drive motor 10 and the drive wheel 5 are installed on the mounting plate 4. The drive wheel 5 is close to the track 1. The displacement drive motor 10 can drive the drive wheel 5 to rotate, thereby driving the trolley to move along the track 1. The power supply 6 is installed on the mounting plate 4 as a movable power supply to power the entire dial angle detection device.

[0039] (3) See Figure 6 The displacement drive motor 10 of the visual inspection device drives the drive wheel 5 to push the camera mounting frame to move the binocular camera 2 to the side of a row of dials 13 to be inspected. Figure 5 , start the angle drive motor 11 to drive the gear system 12 to adjust the angle position of the binocular camera 2 relative to the machine chassis 15 to ensure that each column of dials 13 photographed is within the optimal field of view, and the two cameras simultaneously capture images, and filter and binarize the captured images;

[0040] (4) See Figure 7 , the circular feature detection algorithm is used to extract the boundaries of the high-pixel circular area in the image and obtain the image coordinates of the circle center. The world coordinates of the feature endpoints are calculated based on this. The line connecting the two adjacent feature endpoints is regarded as the center line of the dial. Assume that the world coordinates of the two adjacent feature endpoints are (x w1 ,y w1 , z w1 )、(x w2 ,y w2 , z w2 ), K is the slope of two adjacent characteristic endpoints of the same dial 13 on the projection plane of the machine chassis 15, |θ| is the dial deflection angle, and the dial deflection angle calculation process is as follows:

[0041] When |xw1 -x w2 |<|z w1 -z w2 |, then it is considered that |θ|=0;

[0042] otherwise |θ|=arctan(K).

[0043] Repeat the above steps until the deflection angle of each dial 13 is measured, and the calculated deflection angle value is saved;

[0044] (5) See Figure 8 The dial angle detection device feeds back all the obtained angle values ​​to the control center to correct the angle. The control center corrects the angle in the following way: When the control center control dial 13 is turned counterclockwise |θ|, When the center control dial 13 is turned clockwise |θ|.

[0045] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions based on the principles of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for online measurement of dial angle of a step-by-step rotary three-dimensional braiding machine, characterized in that: The following steps are involved: Step 1: Establish a world coordinate system, calibrate the binocular vision system, and obtain the internal and external parameters of the binocular vision system. The binocular vision system includes a binocular camera. Step 2: Move the binocular camera to the side of a row of dials to be inspected, and capture images with both cameras simultaneously. Step 3: Use feature detection algorithm to extract the feature endpoints of the dial in the image and calculate the world coordinates of the feature endpoints; Step 4: Calculate the slope of the straight line fitted by two adjacent feature endpoints, then calculate the deflection angle value and save it; Step 5: Repeat the above steps until the deflection angle of each dial column is measured; Step 6: Feedback all deflection values ​​to the control center to correct the deflection.

2. The online measurement method for the dial angle of a step-by-step rotary three-dimensional braiding machine according to claim 1 is characterized in that: In step 1, during the movement of the binocular vision system, the coordinate system of the binocular vision system changes; the world coordinate system is a Cartesian coordinate system established with a vertex of the machine chassis of the stepping rotary 3D braiding machine close to the binocular vision system as the origin, and the X, Y, and Z axes of the coordinate system are all vectors parallel to the three edges of the machine chassis of the stepping rotary 3D braiding machine, and the XY plane is parallel to the machine chassis of the stepping rotary 3D braiding machine.

3. The online measurement method for the dial angle of a step-by-step rotary three-dimensional braiding machine according to claim 1 is characterized in that: Two symmetrically distributed circular light sources (14) are embedded on the center line of the dial (13) in step three, which are used to form a high-pixel value circular area after the image is binarized, and the center of the high-pixel value circular area is used as the characteristic endpoint of the dial (13).

4. The online measurement method for the dial angle of a step-by-step rotary three-dimensional braiding machine according to claim 1 is characterized in that: The calculation method for the slope and deflection angle described in step 4 is as follows: When |x w1 -x w2 |<|z w1 -z w2 |, then θ=0; otherwise |θ|=arctan(K); (x w1 ,y w1 , z w1 )、(x w2 ,y w2 , z w2 ) are the world coordinates of the two adjacent feature endpoints of the same dial, K is the slope of the two adjacent feature endpoints of the same dial on the XY plane of the world coordinate system, and |θ| is the deflection angle of the dial.

5. The online measurement method for the dial angle of a step-by-step rotary three-dimensional braiding machine according to claim 4 is characterized in that: The control center correction method in step 5 is: When the control dial in the center is turned counterclockwise |θ|, Turn the center control dial clockwise |θ|.

6. A step-by-step rotary three-dimensional knitting machine dial angle detection device for implementing the online measurement method according to any one of claims 1 to 5, characterized in that: The invention comprises a track (1) and a track trolley; the track trolley comprises a binocular camera (2), a mounting plate (4), two support frames (8) mounted on a mounting surface of the mounting plate (4), a camera mounting frame (7) embedded between the two support frames (8), a guide wheel (3) mounted on the other surface of the mounting plate (4), a driving wheel (5), a displacement driving motor (10), an angle driving motor (11), and a gear system (12); the binocular camera (2) is fixed on the camera mounting frame (7), and an exposure source (9) is installed between the binocular cameras (2); the gear shaft of the input end gear in the gear system (12) is mounted on the On the support frame (8), the gear shaft of the output end gear in the gear system (12) is fixed on the camera mounting frame (7), and the angle driving motor (11) is fixed on the outside of the support frame (8). The angle driving motor (11) drives the input end gear to rotate and drives the output end gear to rotate, thereby realizing the change of the angular position of the camera mounting frame (7); the displacement driving motor (10) and the driving wheel (5) are installed on the mounting plate (4), and the driving wheel (5) is closely attached to the track (1). The displacement driving motor (10) drives the driving wheel (5) to rotate, thereby driving the trolley to move along the track (1).

7. The step-by-step rotary three-dimensional braiding machine dial angle detection device according to claim 6, characterized in that: The two support frames (8) are symmetrically fixed on a certain mounting surface of the mounting plate (4) by fasteners, and the camera mounting frame (7) is embedded in the middle of the two support frames (8) through the two side structures to form a rotation pair.

8. The step-by-step rotary three-dimensional braiding machine dial angle detection device according to claim 6, characterized in that: The guide wheel (3) is tightly fitted on the track (1).

9. The step-by-step rotary three-dimensional braiding machine dial angle detection device according to claim 6, characterized in that: A power supply (6) is installed on the mounting plate (4) as a movable power supply.

10. The step-by-step rotary three-dimensional braiding machine dial angle detection device according to claim 6, characterized in that: The track (1) is distributed around the chassis (15) of the step-by-step rotary three-dimensional knitting machine and the track level should be lower than the height of the knots formed by the yarn interweaving.

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