A method and system for measuring the dimensions of support plate type aerospace connectors

Abstract

This invention provides a method and system for dimensional measurement of support plate-type aerospace connectors, belonging to the field of parts identification and inspection technology. The method includes: acquiring a complete set of spatial position images of the aerospace connector using a time-division control system for imaging differences at the same location; acquiring the rounded corner features of the aerospace connector; removing images of different planes and measuring the planar dimensions of the connector base; acquiring images of features of different planes and measuring the dimensions of the feature regions of different planes. This invention ensures that the visual inspection of the camera imaging plane is not interfered with by imaging of different planes, enabling precise positioning of support plate-type aerospace connectors and completing regional dimensional measurement of multi-angle planar images.

Description

Technical Field

[0001] This invention belongs to the field of parts identification and detection technology, and in particular relates to a method and system for measuring the dimensions of support plate type aviation connectors. Background Technology

[0002] The quality of aircraft connectors directly affects aircraft performance and passenger safety; therefore, the accuracy of dimensional measurements for these connectors must be guaranteed. Currently, most factories still rely on manual measurement by workers, a method that is costly and time-consuming. Using machine vision for part dimensional measurement can improve efficiency and reduce costs. However, during the two-dimensional planar inspection of parts, the resulting images are often complex due to some three-dimensional features of the parts, significantly impacting image analysis and subsequent dimensional measurements. Therefore, to ensure the accuracy of dimensional measurements for aircraft connectors, eliminating interference from dissimilar planes on the imaging plane is particularly important.

[0003] However, due to the complex shape of the support plate-type aerospace connector, which is a spatial non-planar part, removing the non-planar image requires precise acquisition of the connector's features. Generalized image descriptors cannot characterize the connector's positional information. Furthermore, single-view visual measurement cannot obtain the full dimensions of the spatial connector. Therefore, a stable, multi-angle, high-precision position description method is needed to characterize the position of non-planar parts, achieving accurate positioning of the support plate-type aerospace connector while meeting the requirements of high-precision measurement. Most existing technologies can only achieve planar part dimension measurement based on two-dimensional images.

[0004] Therefore, a high-precision dimensional measurement system for support plate-type aerospace connectors needs to be designed. Summary of the Invention

[0005] To address the technical problem that existing technologies cannot achieve precise positioning of support-plate type aerospace connectors while meeting the requirements of high-precision measurement, this invention provides a method and system for measuring the dimensions of support-plate type aerospace connectors. This method ensures that visual inspection of the camera's imaging plane is not interfered with by imaging from dissimilar planes, enables precise positioning of the support-plate type aerospace connector, and allows for regional dimensional measurement of multi-angle planar images. The technical solution is as follows:

[0006] In a first aspect, a method for measuring the dimensions of a support plate-type aerospace connector is provided, the method comprising:

[0007] Step 1: Use a time-division control system for light sources that perform imaging based on differences in the same location to acquire a complete set of spatial location images of the aircraft connectors;

[0008] Step 2: Obtain the fillet features of the aerospace connector;

[0009] Step 3: Remove images with different planes and measure the planar dimensions of the connector base;

[0010] Step 4: Obtain the image of the non-planar feature and measure the size of the non-planar feature region.

[0011] Optionally, the process of building a time-sharing control system for the light source and acquiring images of the differences in lighting conditions at the same location for the aircraft connector includes:

[0012] Step 1.1) Set up a backlighting system: Place the main light source below and to the side of the aircraft connector, respectively, as the backlight source for the top-view camera and the side-view camera. Parallel backlighting is used to ensure that a stable and clear image of the connector outline is obtained.

[0013] Step 1.2) Construct a vertical lighting system: Install a set of strip light sources on both sides of the top-view and side-view cameras, and use an angle gauge to mark the direction of each light source to ensure that the light shines perpendicularly on the surface of the aircraft connector. Since the plane of the support plate and the base plane of the aircraft connector are transitioned with rounded corners, a square shadow effect will appear in this area, which can serve as a separating area between the dissimilar planes.

[0014] Step 1.3) Automatic switching between backlight and strip light source is achieved through time-division control technology to obtain images of the differences between the aviation connectors under different lighting conditions at the same location.

[0015] Optionally, step 1.3) specifically includes:

[0016] Step 1.3.1) In the initial state, the MCU controls the backlight source to switch from the off state to the on state, and the strip light source is in the off state; after the camera takes a picture, it sends a first signal to the PC to indicate that the picture acquisition is complete, where the camera is a top-view camera and a side-view camera;

[0017] Step 1.3.2) After the PC receives the first signal from the camera indicating that the photo acquisition is complete, it sends a first control signal to the MCU. The MCU controls the backlight to turn off and the strip light source to turn on. After the camera takes another photo, it sends a second signal to the PC indicating that the photo acquisition is complete.

[0018] Step 1.3.3) After the PC receives the second signal from the camera indicating that the photo acquisition is complete, it sends a second control signal to the MCU. The MCU controls the strip light source to turn off, completing one photo cycle. Through one photo cycle, backlit images and vertically lit images of the same position in a single direction can be obtained. The top-view camera and the side-view camera perform the above photo cycle operation respectively to obtain a complete set of images of the spatial position of the aviation connector.

[0019] Furthermore, following step 1.3), the following is also included:

[0020] Step 1.4) Adjust the imaging areas of the top-view and side-view cameras so that when the strip light source is turned on, the imaging area of ​​the camera does not include reflected light from the surface of the backlight source, so as not to affect the camera imaging; perform scale calibration on the camera to determine the size value of a unit pixel under the shooting environment.

[0021] Optionally, step 2 specifically includes:

[0022] Step 2.1) Based on the top view images of the aircraft connector under different lighting conditions at the same location obtained in Step 1, the PC uses a threshold segmentation algorithm to obtain images of square shadow areas, counts the number of detected square shadow areas, and automatically adjusts the position of the aircraft connector according to the number of detected square shadow areas.

[0023] Step 2.2) If there is exactly one detected square shadow area, adjust the number of rounded corners at the position of the aviation connector: The PC obtains the edge line by fitting the long side of the rectangular bounding box of the square shadow area, calculates the unit direction vector perpendicular to the line, and points the direction to the square shadow area. The MCU is then instructed to drive the electric cargo platform to move according to the unit direction vector; the center of the rectangular bounding box is moved to the center of the camera's field of view to ensure that two rounded corner areas can be identified.

[0024] Step 2.3) If two square shadow areas are detected, the position difference of the aircraft connector is adjusted: the vertical lighting video of the aircraft connector is input through the camera's video stream mode, and the PC calculates the pixel area of ​​the two detected square shadow areas in real time. If the difference in pixel area between the two square shadow areas is less than the set threshold, the position adjustment is stopped; otherwise, the edge line is obtained by fitting the long side of the square shadow area, the unit direction vector perpendicular to the line is calculated and points to the direction with the larger shadow area, and the MCU is driven to move the electric cargo platform according to the unit direction vector.

[0025] Optionally, step 3 specifically includes:

[0026] Step 3.1) After the electric cargo platform finishes its position adjustment, the PC processes the two images acquired by the top-view camera from the same location under different lighting conditions to remove interference from images of dissimilar planes:

[0027] Step 3.2) After eliminating the interference of different plane imaging, the planar image is divided into regions according to the connectivity relationship. For each sub-region, the PC detects the straight contour of the aviation connector, and the other contours are non-straight contours. Curve fitting is performed on the non-straight contours to extract the straight contour and curved contour of the aviation connector base edge.

[0028] Step 3.3) Based on the scale calibration results obtained in Step 1.4), the PC calculates the length of the straight profile and the feature dimensions of the curved profile, converting the pixel values ​​into actual size values, thereby realizing the measurement of the outer dimensions of the aviation connector base.

[0029] Optionally, step 3.1) specifically includes:

[0030] Step 3.1.1) PC uses a threshold segmentation algorithm to process the vertical illumination image to obtain a square shadow region image;

[0031] Step 3.1.2) PC fits the longer side lines of the two square shaded areas, resulting in four parallel straight lines. The two closest straight lines are selected as the dividing lines.

[0032] Step 3.1.3) The PC applies the dividing line to the backlit image, fills the middle part of the dividing line with a white background, and divides the backlit image into two parts to remove the interference of different plane imaging.

[0033] Optionally, step 4 specifically includes:

[0034] Step 4.1) PC extracts the rounded corner shadow image based on the top-view camera image, segments the rounded corner region, calculates the minimum bounding rectangle of a single rounded corner region, calculates the angles α and β between its long side and short side and the positive X-axis, and calculates the area S of the shadow image corresponding to the rounded corner region, and constructs the rounded corner feature direction descriptor (α,β,S).

[0035] Step 4.2) PC rotates the aviation connector clockwise by an angle α and counterclockwise by an angle (1-β) according to the rounded corner feature descriptor, so that the long side and short side of the rectangle are aligned with the imaging plane of the side-view camera, and the non-plane feature image is obtained through the side-view camera.

[0036] Step 4.3) During the rotation process in Step 4.2), the PC calculates the additional displacement caused by the rotation and instructs the MCU to drive the electric loading platform to reset the position of the aviation connector to the position before the rotation. At the same time, the position of the aviation connector is finely adjusted according to the area S in the rounded corner feature descriptor to ensure that the area of ​​the rounded corner region remains unchanged.

[0037] Step 4.4) The PC determines the clarity of the image and finely adjusts the electric loading platform in a direction perpendicular to the side-view camera to make the side-view camera image clear.

[0038] Step 4.5) After the feature surface of the aviation connector coincides with the imaging plane of the side-view camera, the PC extracts the edge straight lines and curve contours of the aviation connector support plate plane according to step 3.2), thereby completing the measurement of the external dimensions of the aviation connector support plate plane.

[0039] Secondly, a dimensional measurement system for support plate-type aerospace connectors is provided, employing any of the methods described in the first aspect. The system includes: a time-division control system for a light source, an MCU, a PC, and an electric loading platform.

[0040] The MCU is connected to the time-sharing control system for the light source and the PC. The time-sharing control system for the light source is also connected to the PC.

[0041] The electric cargo platform is positioned below the backlight source of the overhead camera and is connected to the MCU.

[0042] Optionally, the time-sharing control system for the light source includes: a top-view camera, a side-view camera, a backlighting system, and a vertical lighting system;

[0043] The backlighting system includes a top-view camera backlight source located below the aircraft connector and a side-view camera backlight source located on the side of the aircraft connector.

[0044] The vertical lighting system includes a set of strip light sources installed on both sides of the top-view camera and the side-view camera.

[0045] The beneficial effects of the dimensional measurement method and system for support plate type aerospace connectors provided by this invention are at least as follows:

[0046] (1) A time-division control system for light source imaging with the same position difference, which realizes the automatic switching between the main light source and the strip light source through time-division control technology, can ensure that the images of the parts are acquired under different lighting conditions.

[0047] (2) The automatic position adjustment method for visual inspection of aviation connectors based on rounded corner areas can ensure that randomly placed aviation connectors can accurately detect a sufficient number of rounded corner features in camera imaging, so as to delete non-surface information;

[0048] (3) The method of measuring the dimensions of aerospace connectors by removing images of different planes can realize the measurement of the plane dimensions of the base of the aerospace connector. The proposed method of adjusting the attitude of the connector can achieve precise spatial positioning by using the rounded corner feature, thus completing the measurement of the dimensions of the connector. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the time-division control system for the light source of the present invention;

[0050] Figure 2 This is a block diagram of the measurement system structure of the present invention;

[0051] Figure 3 This is a diagram illustrating a square-shaped shadow effect.

[0052] Figure 4 This is a schematic diagram illustrating the extraction effect of the square-shaped shadow area;

[0053] Figure 5 A schematic diagram illustrating the effect of removing dissimilar planes in imaging;

[0054] Figure 6 This is a schematic diagram showing the effect of calculating the dimensions of non-planar features. Detailed Implementation

[0055] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0056] like Figure 1 , Figure 2 As shown, this embodiment of the invention provides a method for measuring the dimensions of a support plate-type aerospace connector, comprising the following steps:

[0057] Step 1: Use a time-division control system for light sources that perform imaging based on differences in the same location to acquire a complete set of spatial location images of the aircraft connectors.

[0058] In this embodiment of the invention, parallel backlighting is used for both the top-view and side-view perspectives to obtain a stable and clear outline of the connector. A set of strip light sources is installed on both sides of the top-view and side-view cameras to build a vertical lighting system. The backlight source and the strip light source are switched logically in a time-division manner through time-division control technology to ensure that different images of the aviation connector under different lighting conditions are obtained. The imaging area of ​​the camera is adjusted to ensure that the surface reflection of the backlight source does not affect the imaging when the strip light source is lit.

[0059] In one feasible approach, the process of building a time-division control system for the light source and acquiring images of the differences in lighting conditions at the same location for the aircraft connector is as follows:

[0060] Step 1.1) Construct a backlighting system. Place the main light source below and to the side of the aircraft connector, which are called the backlight source for the top-view camera and the backlight source for the side-view camera, respectively. Parallel backlighting is used to ensure that a stable and clear image of the connector outline is obtained.

[0061] Step 1.2) Construct a vertical lighting system, installing a set of strip light sources on both sides of the top-view camera and the side-view camera, such as... Figure 1 As shown, strip light sources 1 and 2 are installed on either side of the top-view camera, and strip light sources 3 and 4 are installed on either side of the side-view camera. The direction of each light source is calibrated using an angle gauge to ensure that the light hits the surface of the aerospace connector perpendicularly. Because the transition between the support plate plane and the base plane of the aerospace connector is achieved with rounded corners, a square-shaped shadow effect appears in this area, serving as a dividing area between dissimilar planes, such as... Figure 3 As shown.

[0062] Step 1.3) Automatic switching between backlight and strip light source is achieved through time-division control technology to ensure that images of the aviation connectors under different lighting conditions at the same location are acquired separately.

[0063] In one possible implementation, a microcontroller (MCU) and an industrial computer (PC) can be used for control, with the same logic applied to both the top-view and side-view directions, as detailed below:

[0064] Step 1.3.1) Initially, the MCU controls the backlight source to switch from the off state to the on state, while the strip light source is in the off state; after the camera takes a picture, it sends a first signal to the PC to indicate that the picture acquisition is complete.

[0065] Step 1.3.2) After the PC receives the first signal from the camera indicating that the photo acquisition is complete, it sends a first control signal to the MCU to enable the MCU to control the backlight source to turn off and the strip light source to turn on. After the camera takes another photo, it sends a second signal to the PC indicating that the photo acquisition is complete.

[0066] Step 1.3.3) After receiving the second signal from the camera indicating that the photo acquisition is complete, the PC sends a second control signal to the MCU, so that the MCU controls the strip light source to turn off, thus completing one photo-taking cycle;

[0067] Step 1.4) Adjust the imaging areas of the top-view and side-view cameras to ensure that when the strip light source is turned on, the imaging area of ​​the camera does not include reflected light from the backlight source surface, so as not to affect the camera imaging; perform scale calibration on the camera to determine the size value of a unit pixel under the shooting environment.

[0068] A single photo-taking cycle can acquire backlit and vertically lit images of the same location in a single direction. By performing the above photo-taking cycle with both the top-view and side-view cameras, a complete set of images of the spatial location of the connector can be obtained.

[0069] Step 2: Obtain the fillet features of the aerospace connector.

[0070] Due to the presence of non-circular features, support plate-type aircraft connectors require rounded corner transition areas. However, the rounded corner features of randomly placed aircraft connectors are often not fully captured in images. Therefore, an electric platform is used to carry the aircraft connectors, and a threshold segmentation algorithm is used to obtain images of the shadowed areas at the rounded corners of randomly placed aircraft connectors. Based on the number of rounded corner areas detected, the position of the aircraft connectors is adjusted by adjusting the number of rounded corners and the position difference. Adjusting the number of rounded corners ensures that two rounded corner areas are detected, and adjusting the position difference ensures that the difference in pixel area between the two detected rounded corner areas is less than a set threshold, thus achieving accurate acquisition of the rounded corner features of the aircraft connectors.

[0071] In one feasible approach, the process of obtaining the fillet features of the aerospace connector is as follows:

[0072] Step 2.1) Based on the top-view images of the aircraft connectors under different lighting conditions at the same location obtained in Step 1, the PC uses a threshold segmentation algorithm to obtain the square shadow region image described in Step 1.2). The processing result is as follows: Figure 4 As shown, the number of detected square shadow areas is counted, and very small shadow areas are ignored. Based on the number of detected square shadow areas, the adjustment strategies in steps 2.2) and 2.3) are selected to automatically adjust the position of the aviation connector.

[0073] Step 2.2) If only one square-shaped shadow area is detected, adjust the number of rounded corners at the location of the aircraft connector. The PC obtains the edge line by fitting the long side of the rectangular bounding box of the square-shaped shadow area, calculates the unit direction vector perpendicular to this line, and directs it towards the square-shaped shadow area. Based on the unit direction vector, the MCU drives the electric platform to move. Move the center of the rectangular bounding box to the center of the camera's field of view to ensure that both rounded corners can be identified. During the rounded corner adjustment stage, the single control movement time is slightly longer to quickly adjust the aircraft connector to its approximate position and ensure that both rounded corner areas are detected.

[0074] Step 2.3) If two square shadow areas are detected, position difference adjustment is performed on the aircraft connector. The vertical lighting video of the aircraft connector is input via the camera's video stream mode. The PC calculates the pixel area of ​​the two detected square shadow areas in real time. If the difference in pixel area between the two square shadow areas is less than a set threshold, position adjustment stops. Otherwise, similar to Step 2.2), the edge line is obtained by fitting the long side of the square shadow area, and a unit direction vector perpendicular to this line is calculated, pointing towards the direction with the larger shadow area. The unit direction vector instructs the MCU to drive the electric platform to move. During the position difference adjustment stage, the single control movement time is short, ensuring precise position adjustment.

[0075] In adjusting the fillet radius and position difference of the aircraft connector, the corresponding formula for the movement of the electric cargo platform can be expressed as:

[0076]

[0077] in, Let be the unit direction vector of the direction of movement. Let be the displacement vector, step be the step size of the movement (which depends on the speed and time of the electric platform), (x', y') be the coordinates of the electric platform after the movement, and (x, y) be the coordinates of the electric platform before the movement.

[0078] Step 3) Remove the non-planar images and measure the planar dimensions of the connector base.

[0079] Images of the aircraft connector after the electric cargo platform position adjustment are acquired by a top-down camera. Rounded corner features are extracted from images with differences at the same position. Non-imaging plane images are removed to ensure that the size measurement of the aircraft connector base is not disturbed. The Least Significant Difference (LSD) algorithm is used to extract straight lines in the aircraft connector contour. Various curve fittings are performed on non-straight contours to measure the external dimensions of the connector base.

[0080] In one possible approach, removing the non-planar images and measuring the planar dimensions of the connector base can specifically include the following steps:

[0081] Step 3.1) After adjusting the end position of the electric cargo platform, as follows: Figure 5 As shown, the PC processes two images acquired by a top-down camera from the same location under different lighting conditions to remove interference from images of dissimilar planes:

[0082] Step 3.1.1) PC uses a threshold segmentation algorithm to process the vertical illumination image to obtain a square shadow region image;

[0083] Step 3.1.2) PC fits the longer side lines of the two square shaded areas, resulting in four parallel straight lines. The two closest straight lines are selected as the dividing lines.

[0084] Step 3.1.3) The PC applies the dividing line to the backlit image, fills the middle part of the dividing line with a white background, and divides the backlit image into two parts to remove the interference of different plane imaging.

[0085] Step 3.2) After eliminating the interference of different plane imaging, the planar image is divided into regions according to the connectivity relationship. For each sub-region, the PC uses the LSD algorithm to detect the straight contour of the aviation connector. The remaining contours are non-straight contours. Various common curve fittings are performed on the non-straight contours to extract the straight contour and curved contour of the aviation connector base edge.

[0086] Step 3.3) Based on the scale calibration results obtained in Step 1.4), the PC calculates the length of the straight profile and the feature dimensions of the curved profile, converting the pixel values ​​into actual size values, thereby realizing the measurement of the outer dimensions of the aviation connector base.

[0087] Step 4) Obtain the image of the non-planar feature and measure the size of the non-planar feature region.

[0088] The position and orientation of the rounded corner area of ​​the aircraft connector are identified by the top-view camera image. The minimum bounding rectangle of the image of a single rounded corner area is obtained. The rounded corner feature direction descriptor is designed. The long side and short side of the above rectangle are aligned with the imaging plane of the side-view camera in sequence. The non-surface feature image is obtained by the side-view camera. The non-surface feature area of ​​the aircraft connector is accurately measured according to the same measurement method as in step 3).

[0089] In one feasible approach, the process of dimensionally measuring the non-planar feature regions of an aerospace connector may include the following steps:

[0090] Step 4.1) PC extracts the rounded corner shadow image based on the top-view camera image, segments the rounded corner region, calculates the minimum bounding rectangle of a single rounded corner region, calculates the angles α and β between its long side and short side and the positive X-axis, and calculates the area S of the shadow image corresponding to the rounded corner region, and constructs the rounded corner feature direction descriptor (α,β,S).

[0091] Step 4.2) PC rotates the aviation connector clockwise by an angle α and counterclockwise by an angle (1-β) according to the rounded corner feature descriptor, so that the long side and short side of the rectangle are aligned with the imaging plane of the side-view camera, and the non-plane feature image is obtained through the side-view camera.

[0092] Step 4.3) During the rotation process in Step 4.2), the PC uses the affine transformation principle to calculate the additional displacement caused by the rotation and instructs the MCU to drive the electric loading platform to reset the position of the aviation connector to the position before the rotation. At the same time, the position of the aviation connector is finely adjusted according to the area S in the rounded corner feature descriptor to ensure that the area of ​​the rounded corner region remains unchanged.

[0093] Step 4.4) The PC determines the sharpness of the image based on the Laplacian value of the image, and uses the PID algorithm to fine-tune the electric cargo platform along the direction perpendicular to the side-view camera to make the side-view camera image clear.

[0094] Step 4.5) After the feature surface of the aircraft connector coincides with the imaging plane of the side-view camera, the PC uses the same method as in Step 3.2) to extract the edge straight lines and curved contours of the aircraft connector support plate plane, thereby realizing the measurement of the external dimensions of the aircraft connector support plate plane. The effect of the dimension measurement is as follows: Figure 6 As shown.

[0095] like Figure 1 , Figure 2 As shown, one embodiment of the present invention also provides a dimensional measurement system for support plate-type aerospace connectors, including: a time-division control system for a light source, an MCU, a PC, and an electric loading platform.

[0096] The MCU is connected to the time-sharing control system for the light source and the PC. The time-sharing control system for the light source is also connected to the PC.

[0097] The electric cargo platform is positioned below the backlight source of the overhead camera and is connected to the MCU.

[0098] In one embodiment, the time-division control system for the light source includes: a top-view camera, a side-view camera, a backlight illumination system, and a vertical illumination system;

[0099] The backlighting system includes a top-view camera backlight source located below the aircraft connector and a side-view camera backlight source located on the side of the aircraft connector.

[0100] The vertical lighting system includes a set of strip light sources installed on both sides of the top-view camera and the side-view camera.

[0101] In summary, the present invention provides a dimensional measurement system and method for support plate-type aerospace connectors, mainly including a time-division control system for imaging differences at the same position, automatic position adjustment for aerospace connectors based on rounded corner regions for visual inspection, an algorithm for eliminating out-of-plane images and measuring the plane dimensions of the connector base, and an algorithm for spatial positioning and out-of-plane dimension measurement of aerospace connectors based on rounded corner features. The invention first proposes a time-division control system for imaging differences at the same position, enabling automatic switching between the main light source and the strip light source to ensure the acquisition of images of parts at the same position under different lighting conditions. The automatic position adjustment method for aerospace connectors based on rounded corner regions employs a linkage between a vision system based on rounded corner features and an electric loading platform, adjusting the position of the workpiece to be identified according to the number and area of ​​the rounded corner regions to ensure complete acquisition of the plane image of the aerospace connector base. The algorithm for eliminating out-of-plane images and measuring the plane dimensions of the aerospace connector base achieves accurate measurement of the plane dimensions of the out-of-plane connector base, containing only information within the camera's imaging plane. The algorithm for spatial positioning and out-of-plane dimension measurement of aerospace connectors based on rounded corner features accurately locates the out-of-plane features of the out-of-plane connector through rounded corner features, sequentially acquiring the dimensions of the spatial feature surfaces of the connector.

[0102] To verify the feasibility and effectiveness of the system and method of this invention, an experiment was conducted on a typical scenario, and the accuracy of the method was evaluated.

[0103] For example, the size estimation results of five different sizes of aerospace connectors are shown in Table 1:

[0104] Table 1. Image data of aircraft connectors

[0105]

[0106] According to the test data, the measurement error of the method and system proposed in this invention is within 0.3 mm, which meets the accuracy requirements.

[0107] The above description merely illustrates embodiments of the present invention and is quite specific and detailed; however, it should not be construed as limiting the scope of the patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Furthermore, any parts of the present invention not described in detail are conventional techniques.

Claims

1. A method for measuring the dimensions of a support plate type aerospace connectors, characterized in that, The method includes: Step 1: Use a time-division control system for light sources that perform imaging based on differences in the same location to acquire a complete set of spatial location images of the aircraft connectors; Step 2: Obtain the fillet features of the aerospace connector: Step 2.1) Based on the top view images of the aircraft connector under different lighting conditions at the same location obtained in Step 1, the PC uses a threshold segmentation algorithm to obtain images of square shadow areas, counts the number of detected square shadow areas, and automatically adjusts the position of the aircraft connector according to the number of detected square shadow areas. Step 2.2) If there is exactly one detected square shadow area, adjust the number of rounded corners at the position of the aviation connector: The PC obtains the edge line by fitting the long side of the rectangular bounding box of the square shadow area, calculates the unit direction vector perpendicular to the line, and points the direction to the square shadow area. The MCU is then instructed to drive the electric cargo platform to move according to the unit direction vector; the center of the rectangular bounding box is moved to the center of the camera's field of view to ensure that two rounded corner areas can be identified. Step 2.3) If two square shadow areas are detected, adjust the position difference of the aircraft connector: Input the vertical lighting video of the aircraft connector through the camera's video stream mode, and the PC calculates the pixel area of ​​the two detected square shadow areas in real time. If the difference in pixel area between the two square shadow areas is less than the set threshold, stop the position adjustment; otherwise, obtain the edge line by fitting the long side of the square shadow area, calculate the unit direction vector perpendicular to the line, and point it in the direction of the larger shadow area. Instruct the MCU to drive the electric cargo platform to move according to the unit direction vector. Step 3: Remove images with different planes and measure the planar dimensions of the connector base; Step 4: Obtain the image of the non-planar feature and measure the size of the non-planar feature region.

2. The method according to claim 1, characterized in that, The process of building a time-sharing control system for the light source and acquiring images of the differences in lighting conditions at the same location for aircraft connectors includes: Step 1.1) Construct a backlighting system: Place the main light source below and to the side of the aircraft connector, respectively, as the backlight source for the top-view camera and the side-view camera, and use parallel backlighting for both. Step 1.2) Build a vertical lighting system: Install a set of strip light sources on both sides of the top-view camera and the side-view camera, and mark the direction of each light source to ensure that the light shines vertically on the surface of the aircraft connector. Step 1.3) Automatic switching between backlight and strip light source is achieved through time-division control technology to obtain images of the differences between the aviation connectors under different lighting conditions at the same location.

3. The method according to claim 2, characterized in that, Step 1.3) specifically includes: Step 1.3.1) In the initial state, the MCU controls the backlight source to switch from the off state to the on state, and the strip light source is in the off state; after the camera takes a picture, it sends a first signal to the PC to indicate that the picture acquisition is complete, where the camera is a top-view camera and a side-view camera; Step 1.3.2) After the PC receives the first signal from the camera indicating that the photo acquisition is complete, it sends a first control signal to the MCU. The MCU controls the backlight to turn off and the strip light source to turn on. After the camera takes another photo, it sends a second signal to the PC indicating that the photo acquisition is complete. Step 1.3.3) After the PC receives the second signal from the camera indicating that the photo acquisition is complete, it sends a second control signal to the MCU. The MCU controls the strip light source to turn off, completing one photo cycle. Through one photo cycle, backlit images and vertically lit images of the same position in a single direction can be obtained. The top-view camera and the side-view camera perform the above photo cycle operation respectively to obtain a complete set of images of the spatial position of the aviation connector.

4. The method according to claim 2, characterized in that, Following step 1.3), it also includes: Step 1.4) Adjust the imaging areas of the top-view and side-view cameras so that when the strip light source is turned on, the imaging area of ​​the camera does not include the reflected light from the surface of the backlight source; perform scale calibration on the camera.

5. The method according to claim 4, characterized in that, Step 3 specifically includes: Step 3.1) After the electric cargo platform finishes its position adjustment, the PC processes the two images acquired by the top-view camera from the same location under different lighting conditions to remove interference from images of dissimilar planes: Step 3.2) After eliminating the interference of different plane imaging, the planar image is divided into regions according to the connectivity relationship. For each sub-region, the PC detects the straight contour of the aviation connector, and the other contours are non-straight contours. Curve fitting is performed on the non-straight contours to extract the straight contour and curved contour of the aviation connector base edge. Step 3.3) Based on the scale calibration results obtained in Step 1.4), the PC calculates the length of the straight profile and the feature dimensions of the curved profile, converting the pixel values ​​into actual size values, thereby realizing the measurement of the outer dimensions of the aviation connector base.

6. The method according to claim 5, characterized in that, Step 3.1) specifically includes: Step 3.1.1) PC uses a threshold segmentation algorithm to process the vertical illumination image to obtain a square shadow region image; Step 3.1.2) PC fits the longer side lines of the two square shaded areas, resulting in four parallel straight lines. The two closest straight lines are selected as the dividing lines. Step 3.1.3) The PC applies the dividing line to the backlit image, fills the middle part of the dividing line with a white background, and divides the backlit image into two parts to remove the interference of different plane imaging.

7. The method according to claim 1, characterized in that, Step 4 specifically includes: Step 4.1) PC extracts the rounded corner shadow image based on the top-view camera image, segments the rounded corner region, calculates the minimum bounding rectangle of a single rounded corner region, calculates the angles α and β between its long side and short side and the positive X-axis, and calculates the area S of the shadow image corresponding to the rounded corner region, and constructs the rounded corner feature direction descriptor (α,β,S). Step 4.2) PC rotates the aviation connector clockwise by an angle α and counterclockwise by an angle (1-β) according to the rounded corner feature descriptor, so that the long side and short side of the rectangle are aligned with the imaging plane of the side-view camera, and the non-plane feature image is obtained through the side-view camera. Step 4.3) During the rotation process in Step 4.2), the PC calculates the additional displacement caused by the rotation and instructs the MCU to drive the electric loading platform to reset the position of the aviation connector to the position before the rotation. At the same time, the position of the aviation connector is finely adjusted according to the area S in the rounded corner feature descriptor to ensure that the area of ​​the rounded corner region remains unchanged. Step 4.4) The PC determines the clarity of the image and finely adjusts the electric loading platform in a direction perpendicular to the side-view camera to make the side-view camera image clear. Step 4.5) After the feature surface of the aviation connector coincides with the imaging plane of the side-view camera, the PC extracts the edge straight lines and curve contours of the aviation connector support plate plane according to step 3.2), thereby completing the measurement of the external dimensions of the aviation connector support plate plane.

8. A dimensional measurement system for support plate type aerospace connectors, characterized in that, The system, employing the method described in any one of claims 1 to 7, comprises: a time-sharing control system for a light source, an MCU, a PC, and an electric loading platform. The MCU is connected to the time-sharing control system for the light source and the PC. The time-sharing control system for the light source is also connected to the PC. The electric cargo platform is positioned below the backlight source of the overhead camera and is connected to the MCU.

9. The system according to claim 8, characterized in that, The time-sharing control system for light sources includes: a top-view camera, a side-view camera, a backlighting system, and a vertical lighting system; The backlighting system includes a top-view camera backlight source located below the aircraft connector and a side-view camera backlight source located on the side of the aircraft connector. The vertical lighting system includes a set of strip light sources installed on both sides of the top-view camera and the side-view camera.

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