Aircraft radome rivet detection device and detection method

Abstract

The invention discloses an aircraft radome rivet detection device and method. The aircraft radome rivet detection device comprises a control unit and a detection instrument. The detection instrument obtains pressure value data or image data of the to-be-detected rivet when the surface of the to-be-detected rivet is contacted; the control unit detects the flush degree of the surface of the rivet to be detected according to the pressure value data; the control unit performs flush degree detection or roundness detection according to the image data of the rivet to be detected; the detection instrument is arranged on the annular track through the detection trolley, and the detection trolley drives the detection instrument to move along the annular track. Through coordination and cooperation among parts of the automatic detection device, automatic detection of the aircraft meteorological radome rivets is realized, the manual labor cost and time are saved, the efficiency and accuracy of rivet installation and detection are improved, and standardized and streamlined follow-up research of automatic detection can be realized.

Description

Technical Field

[0001] The present invention relates to an aircraft radome rivet detection device and a detection method, belonging to the technical field of automation equipment. Background Art

[0002] With the rapid development of the aircraft manufacturing industry, safety detection in the aircraft manufacturing process cannot be ignored. Since most of the composite materials used in aircraft skins are mainly aluminum alloy and carbon fiber metal, aircraft skins need to be riveted. Therefore, the most important thing is to detect the rivets at the riveted joints of the aircraft.

[0003] Rivets are the most commonly selected standard parts for aircraft structural connection design. A light aircraft uses as many as 140,000 rivets, and an Airbus A380 uses up to 5 million rivets. Traditional manual detection not only has a high labor cost, but also has extremely high professional requirements for the personnel engaged in detection. At the same time, traditional detection methods such as visual inspection and manual measurement have problems such as low detection efficiency, insufficient accuracy and reliability, and cannot fully ensure the safety of the rivets at the riveted joints of the aircraft. Summary of the Invention

[0004] The purpose of the present invention is to provide an aircraft radome rivet detection device and a detection method, which can save labor costs and time and improve detection efficiency and detection accuracy through the automatic adjustment of the detection equipment.

[0005] To achieve the above object / to solve the above technical problems, the present invention is implemented by the following technical solutions.

[0006] On the one hand, the present invention provides an aircraft radome rivet detection device, including: a control unit and a detection instrument;

[0007] The detection instrument obtains pressure value data or image data of the rivet to be measured when contacting the surface of the rivet to be measured;

[0008] The image data of the rivet to be measured includes: front image data of the rivet head, side image data of the rivet head, and IMU data;

[0009] The control unit performs flatness detection on the surface of the rivet to be measured according to the pressure value data;

[0010] The control unit performs flatness detection on the surface of the rivet to be measured according to the side image data of the rivet head and the IMU data;

[0011] The control unit performs roundness detection on the rivet to be measured according to the front image data of the rivet head.

[0012] Further, the detection instrument is arranged on a circular track through a detection trolley. The detection trolley drives the detection instrument to move along the circular track to obtain the pressure value data or the image data of the rivet to be measured when contacting the surface of the rivet to be measured.

[0013] The circular track includes: a circular frame with an I-shaped cross-section and a circular tooth circulating track concentrically connected thereto. In the inner circumference of the circular frame, a circular groove is provided, and on the outer circumference of the circular tooth circulating track, a protruding circular guide rail is designed. The size of the circular guide rail matches the groove on the inner circumference of the circular frame.

[0014] The detection trolley includes: a receiving plate, a first wheel body, a small gear, a telescopic rod, a detection instrument, and a second servo motor. One end of the receiving plate is rotatably connected to the first wheel body that is slidably connected to the circular frame. The middle of the receiving plate is connected to the second servo motor. The second servo motor is connected to the small gear that meshes with the circular tooth circulating track through a shaft. One end of the telescopic rod is connected to the detection trolley, and the other end is connected to the detection instrument.

[0015] When the detection instrument is a pressure sensor, the pressure sensor is fixedly connected to the receiving plate through the telescopic rod.

[0016] When the detection instruments are a front-view camera and an auxiliary camera, the front-view camera is fixedly connected to the receiving plate. The auxiliary camera is placed on the side of the front-view camera through a support rod, and the viewing angle between the front-view camera and the auxiliary camera is 45°. The telescopic rod extends the detection instruments to the surface of the rivet head. As the detection trolley travels around the track for one week, it is detected whether the flatness or roundness of the aircraft radome rivets meets the requirements.

[0017] Further, it also includes: a slide rail, a base, and a second wheel body. The base is slidably connected to the slide rail through the connected second wheel body. The upper surface of the base is connected to a platform frame, and the outer lower part of the circular frame is connected to the platform frame. A plurality of infrared distance sensors are arranged around the circular frame for counting and correcting the number of rivets per 1 / 4 circumference during the detection process.

[0018] Further, a jacking mechanism is arranged between the base and the platform frame. The jacking mechanism includes: a hydraulic strut, a first servo motor, and a ball screw.

[0019] The first servo motor is installed on the base. One end of the ball screw is connected to the platform frame through a nut pair, and the other end is connected to the first servo motor.

[0020] The hydraulic struts are symmetrically arranged on both sides of the first servo motor. The pressure pipes of the hydraulic struts are connected to the base, and their piston rods are connected to the platform frame, so as to share the load of the annular track, ensure that the lifting mechanism has a certain self-locking property, and at the same time ensure the stability of the whole equipment during the circumferential inspection of the inspection trolley.

[0021] Second, the present invention provides a method for detecting the flatness of aircraft radome rivets, which uses the above-mentioned aircraft radome rivet detection device for detection. The method includes:

[0022] Collect the pressure signal at the position of the rivet to be measured through the pressure sensor. If the pressure value distribution on the contact surface of the rivet to be measured is uniform and the pressure signal intensity is consistent, the heights of the rivets to be measured are exactly the same;

[0023] If the pressure signal intensity in the middle of the contact surface of the rivet to be measured is higher than the average value of the adjacent areas, the rivet to be measured protrudes;

[0024] If the pressure signal intensity in the middle of the contact surface of the rivet to be measured is lower than the average value of the adjacent areas, the rivet to be measured is sunken;

[0025] Through the pressure sensor, the digital measurement of the pressure distribution on the contact surface of the rivet head can be realized. Compared with the traditional visual inspection, the height difference of ±0.01mm level of the rivet head installation can be detected, and at the same time, the continuous operation mode is supported to meet the detection requirements of the large size of the aircraft radome and the large number of rivets.

[0026] Third, the present invention provides a method for detecting the flatness of aircraft radome rivets, which uses the above-mentioned aircraft radome rivet detection device for detection. The method includes:

[0027] Obtain the side image data and IMU data of the rivet head to be measured through the auxiliary camera;

[0028] Store the side image data and IMU data of the rivet head in chronological order;

[0029] Preprocess the side image data of the rivet head, and use different polarization angles to obtain the specular reflection feature information of the side of the rivet head to make the side image data information of the rivet head clear;

[0030] Preprocess the IMU data, and obtain the local map information of the rivet based on the sliding window method. Combine the front image data of the rivet head to be measured obtained through the main view camera by using the triangulation method to construct the global map information of the rivet;

[0031] According to the global rivet map information and in combination with the time sequence during data collection, match the side image of the rivet head with its corresponding front image of the rivet head, and determine whether the side flatness and front roundness of the rivet meet the aviation standards, so as to accurately judge whether the rivet installation meets the aviation standards from multiple dimensions.

[0032] Fourthly, the present invention provides a method for detecting the roundness of aircraft radome rivets. The detection is carried out by using the above-mentioned aircraft radome rivet detection device. The method includes:

[0033] Obtain the front image data of the rivet head to be measured through the front camera, and perform denoising and smoothing processing on the front image data of the rivet head to be measured;

[0034] Perform grayscale processing on the image of the rivet head to be measured after denoising and smoothing processing, and separate the roundness features of the rivet head to be measured from the image background through binarization of the grayscale processed image;

[0035] Perform Laplace edge detection on the separated roundness features of the rivet head to be measured to obtain the contour information of the rivet head to be measured;

[0036] Evaluate the roundness error of the edge contour of the rivet head to be measured by using the minimum circumscribed region method according to the contour information of the rivet head to be measured.

[0037] Further, the evaluation of the roundness error of the edge contour of the rivet head to be measured by using the minimum circumscribed region method according to the contour information of the rivet head to be measured specifically includes:

[0038] Select 4 control points from the contour edge points of the rivet head to be measured, where the inner circles and outer circles are alternately distributed and arranged in the same direction;

[0039] Connect two control points on a set of inner and outer circles of the contour edge to form a straight line L1, and find the perpendicular bisector B1 of the straight line L1. Connect two control points on another set of inner and outer circles to form a straight line L2, and find the perpendicular bisector B2 of the straight line L2. Calculate the intersection coordinates of B1 and B2, and take the intersection as the theoretical center of the concentric circles;

[0040] Calculate the roundness error according to the distance between the theoretical center and the above control points ;

[0041] Where: is the maximum distance between the theoretical center and the control points, is the minimum distance between the theoretical center and the control points;

[0042] Select several measuring points on the contour edge attachment. If the distances from all the measuring points to the theoretical center of the circle are within the roundness error, the roundness detection meets the requirements; if there are measuring points whose distances to the theoretical center of the circle are outside the roundness error, the roundness detection does not meet the requirements. Therefore, the minimum zone method can accurately calculate the roundness error of the rivet head, and at the same time, the measurement results can reflect the shape fluctuations, which is suitable for evaluating the stability of the manufacturing process.

[0043] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: Through the coordinated cooperation among the parts of the automatic detection device, the present invention realizes the automatic detection of the rivets at the riveting joints of the aircraft weather radar cover, saves labor costs and time, improves the efficiency and accuracy of the rivet installation detection, and can utilize the present invention for the subsequent research on the standardization and serialization of the automatic detection of the aircraft radar cover rivet installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is the overall structure diagram of the present invention;

[0045] Figure 2 is the front view of the present invention;

[0046] Figure 3 is the partial view of the contact detection trolley in the present invention;

[0047] Figure 4 is the partial view of the non-contact detection trolley in the present invention;

[0048] Figure 5 is the schematic diagram of the flatness detection process of an embodiment;

[0049] Figure 6 is the schematic diagram of the method flow for detecting the roundness error of the edge contour of the rivet head to be measured by the minimum zone method of the present invention;

[0050] Figure 7 is the schematic diagram of the triangulation method process.

[0051] In the figure: base 1, second wheel body 2, hydraulic strut 3, first servo motor 4, ball screw 5, platform frame 6, annular frame 7, ring gear circulating track 8, receiving plate 9, infrared distance sensor at position 1 10, infrared distance sensor at position 2 11, infrared distance sensor at position 3 12, infrared distance sensor at position 4 13, first wheel body 14, pinion 15, telescopic rod 16, pressure sensor 17, second servo motor 18, main view camera 19, auxiliary camera 20. DETAILED DESCRIPTION OF THE INVENTION

[0052] It should be noted that:

[0053] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations on the technical solution of the present invention. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0054] The term "and / or" simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " generally indicates an "or" relationship between the related objects.

[0055] Example 1

[0056] like Figures 1 to 4 An embodiment shown in FIG. 1 provides an aircraft radome rivet detection device, comprising: a control unit and a detection instrument;

[0057] The testing instrument obtains pressure value data or image data of the rivet to be tested when contacting the surface of the rivet to be tested;

[0058] The image data of the rivet to be tested includes: front image data of the rivet head, side image data of the rivet head and IMU data;

[0059] The control unit performs a flatness detection on the surface of the rivet to be tested according to the pressure value data;

[0060] The control unit detects the flatness of the rivet surface to be tested based on the side image data of the rivet head and the IMU data;

[0061] The control unit detects the roundness of the rivet to be tested based on the front image data of the rivet head.

[0062] The detection instrument is arranged on a circular track by a detection trolley, and the detection trolley drives the detection instrument to move along the circular track to obtain pressure value data when contacting the surface of the rivet to be tested or image data of the rivet to be tested;

[0063] The annular track comprises: an annular frame 7 with an I-shaped cross section and an annular toothed circulating track 8 concentrically connected thereto, wherein the annular frame 7 and the annular toothed circulating track 8 are provided with an annular groove on the inner periphery of the annular frame 7, and a protruding annular guide rail is designed on the outer periphery of the annular toothed circulating track 8, and the size of the annular guide rail matches the groove on the inner periphery of the annular frame 7;

[0064] The inspection trolley includes: a receiving plate 9, a first wheel body 14, a pinion gear 15, a telescopic rod 16, an inspection instrument, and a second servo motor 18; one end of the receiving plate 9 is rotatably connected to the first wheel body 14 that is slidably connected to the annular frame 7, the middle of the receiving plate 9 is connected to the second servo motor 18, and the second servo motor 18 is connected by a shaft to the pinion gear that is meshed with the circular tooth circulating track 8. One end of the telescopic rod 16 is connected to the inspection trolley, and the other end is connected to the inspection instrument;

[0065] When the inspection instrument is a pressure sensor 17, the pressure sensor 17 is fixedly connected to the receiving plate 9 through the telescopic rod 16;

[0066] When the inspection instruments are a front-view camera 19 and an auxiliary camera 20, the front-view camera 19 is fixedly connected to the receiving plate 9, the auxiliary camera 20 is placed on the side of the front-view camera 19 through a support rod, and the viewing angle between the front-view camera 19 and the auxiliary camera 20 is 45°;

[0067] The telescopic rod 16 extends the inspection instrument to the surface of the rivet head. As the inspection trolley travels around the track for one week, it is detected whether the flatness or roundness of the aircraft radome rivets meets the requirements.

[0068] It further includes: a slide rail, a base 1, and a second wheel body 2. The base 1 is slidably connected to the slide rail through the connected second wheel body 2. The upper surface of the base 1 is connected to a platform frame 6, and the lower part of the outer side of the annular frame 7 is connected to the platform frame 6. A plurality of infrared distance sensors are arranged around the annular frame 7 for counting and correcting the number of rivets in each 1 / 4 circumference during the inspection process;

[0069] The 4 infrared distance sensors can provide an error correction mechanism for the automatic detection device. The specific implementation steps are as follows: The infrared distance sensor 10 at the No. 1 position can judge whether the inspection trolley is placed at the correct initial position. The remaining infrared distance sensors 11 at the No. 2 position, 12 at the No. 3 position, and 13 at the No. 4 position respectively give prompts when the inspection trolley travels to each 1 / 4 circumference, and the inspection trolley needs to count the rivets in this 1 / 4 circumference. If the counted number of rivets deviates greatly from the specified value, an alarm should be issued and the detection should be stopped. After readjusting the automatic detection device to a suitable position, the detection should be restarted.

[0070] A jacking mechanism is arranged between the base 1 and the platform frame 6. The jacking mechanism includes: a hydraulic strut 3, a first servo motor 4, and a ball screw 5;

[0071] The first servo motor 4 is installed on the base. One end of the ball screw 5 is connected to the platform frame 6 through a nut pair, and the other end is connected to the first servo motor;

[0072] The hydraulic struts 3 are symmetrically arranged on both sides of the first servo motor 4. The pressure pipes of the hydraulic struts 3 are connected to the base, and their piston rods are connected to the platform frame 6, so as to share the load of the annular track, ensure that the jacking mechanism has a certain self-locking property, and at the same time ensure the stability of the whole equipment during the circumferential inspection of the inspection trolley.

[0073] The working process of this embodiment: Place the base 1 on the track in the aircraft assembly workshop, and use the second wheel body 2 to make the device move horizontally. Then start the ball screw 5 jacking mechanism. The first servo motor 4 drives the ball screw 5 to lift the platform frame 6 to achieve the vertical jacking movement. At the same time, the two hydraulic struts ensure the self-locking property of the jacking mechanism. Then, the movable inspection trolley cooperates with the first wheel body 14 and the I-shaped cross-section annular frame 7 to ensure the stability during the circumferential inspection. Then, the telescopic rod 16 drives the pressure sensor 17 to be placed on the circumferential surface where the riveting joint of the aircraft radome skin is located. Finally, after ensuring that the device is aligned with the aircraft to be inspected, drive the pinion 15 through the second servo motor 14 to achieve the circumferential movement of the movable inspection trolley.

[0074] When a contact type inspection trolley is formed by using a pressure sensor in this embodiment, a telescopic rod 16 drives the pressure sensor 17 and places it at a suitable inspection position, that is, on the circumferential surface where the riveting joint of the aircraft radome skin is located. Finally, after ensuring that the device is aligned with the aircraft to be inspected, drive the pinion 15 connected to its shaft through the second servo motor 14 with an electromagnetic brake. The pinion 15 meshes with the circular tooth circulating track 8 to achieve the circumferential movement of the movable inspection trolley. At the same time, the pressure sensor 17 collects the change information of the pressure when passing through different positions, and can analyze and judge whether the rivet flatness is qualified according to the preset algorithm, and control the running state of the second servo motor 14 according to the detection result. For example, when it is detected that the rivet flatness is unqualified, the inspection trolley can be stopped or specific marks can be made through instructions, and at the same time, record various data during the inspection process, including the inspection position, pressure value change, inspection time, etc., for subsequent data analysis and processing, so as to realize the automatic control and data management of the whole inspection process.

[0075] When a non-contact type inspection trolley is formed by using a binocular camera in this embodiment, the binocular camera is used to detect the rivets. Among them, the industrial camera takes pictures of the front of the rivet head of the riveting joint of the aircraft radome skin and imports the characteristic information into the computer system to obtain the image information of the rivets to be measured. Secondly, perform image Gaussian filtering denoising, image binarization processing on the identified image information in the MATLABA environment, extract the Laplace edge features of the grayscale image, and obtain the image contour information. Finally, use the minimum circumscribed region method to evaluate the roundness error of the edge contour and determine whether the roundness error of the rivet meets the requirements.

[0076] The auxiliary camera takes pictures of the side of the rivet head to determine whether the flatness of the rivet installation meets the standard. First, the internal parameters (such as focal length, distortion, etc.) and external parameters (the position and orientation of the camera) of the auxiliary camera are adjusted to the appropriate parameters suitable for industrial cameras. Then, after correcting the two images, corresponding pixel points are found for stereo matching. Finally, by calculating the parallax, the depth information of each pixel point is obtained; combining the known camera parameters and the matching parallax, the depth of the pixel points is converted into three-dimensional coordinates using the triangulation method, and a dense depth point cloud is generated in the process. The three-dimensional model of the object can be reconstructed using the depth point cloud.

[0077] Therefore, the non-contact detection trolley can present the accurate three-dimensional spatial information of the target, which is convenient for judging whether the installation error during the rivet installation meets the requirements from multiple angles. If the error is within the reasonable range, it means that the flatness of the rivet at this place meets the requirements and the next process can be entered; if the error is outside the reasonable range, it means that the flatness of the rivet at this place does not meet the requirements and the next process cannot be entered, and operations such as rework should be carried out according to the actual situation.

[0078] Embodiment 2

[0079] This embodiment provides a method for detecting the flatness of aircraft radome rivets, which is detected using the above-mentioned aircraft radome rivet detection device. The method includes:

[0080] The pressure sensor is used to collect the pressure signal at the position of the rivet to be measured. If the pressure value distribution on the contact surface of the rivet to be measured is uniform and the pressure signal intensity is consistent, the heights of the rivets to be measured are exactly the same;

[0081] If the pressure signal intensity in the middle of the contact surface of the rivet to be measured is higher than the average value of the adjacent areas, the rivet to be measured protrudes;

[0082] If the pressure signal intensity in the middle of the contact surface of the rivet to be measured is lower than the average value of the adjacent areas, the rivet to be measured is sunken;

[0083] The digital measurement of the pressure distribution on the contact surface of the rivet head can be realized through the pressure sensor. Compared with the traditional visual inspection, the height difference of ±0.01mm level of the rivet head installation can be detected, and at the same time, it supports the continuous operation mode, meeting the detection requirements of the large size of the aircraft radome and the large number of rivets.

[0084] Embodiment 3

[0085] As Figure 5 shown, this embodiment provides a method for detecting the flatness of aircraft radome rivets, which is detected using the above-mentioned aircraft radome rivet detection device. The method includes:

[0086] The side image data of the rivet head and the corresponding IMU data are obtained through the auxiliary camera;

[0087] Store the image data and IMU data in chronological order in a computer;

[0088] Preprocess the image data, and utilize different polarization angles to obtain the reflective feature information of the rivet head side, that is, separate specular reflection (polarization-sensitive) and diffuse reflection (non-polarized), so as to make the image information of the rivet head side clear; <s

[0089] Preprocess the IMU data, and obtain the local map information of the rivet based on the sliding window method. Combine the front image data of the rivet head using the triangulation method to construct the global map information of the rivet;

[0090] According to the global map information of the rivet, combined with the chronological order during data acquisition, match the side image of the rivet head with its corresponding front image of the rivet head, and judge whether the side flatness and front roundness of the rivet meet the aviation standards. If the error is within a reasonable range, it means that the flatness of the rivet at this place meets the requirements and can enter the next process; if the error is outside the reasonable range, it means that the flatness of the rivet at this place does not meet the requirements and cannot enter the next process, and rework and other operations should be carried out according to the actual situation.

[0091] Embodiment 4

[0092] As Figure 6 shown, this embodiment provides a method for detecting the roundness of aircraft radome rivets. The detection is carried out using the above-mentioned aircraft radome rivet detection device. The method includes:

[0093] Obtain the front image information of the rivet head to be measured through the front camera 19, and perform denoising and smoothing processing on the image information of the rivet head to be measured;

[0094] Perform gray-scale processing on the image of the rivet head to be measured after denoising and smoothing processing, and separate the roundness features of the rivet head to be measured from the image background through binarization;

[0095] Perform Laplace edge detection on the separated roundness features of the rivet head to be measured to obtain the contour information of the rivet head to be measured;

[0096] Evaluate the roundness error of the edge contour of the rivet head to be measured using the minimum circumscribed region method according to the contour information of the rivet head to be measured.

[0097] The evaluation of the roundness error of the edge contour of the rivet head to be measured using the minimum circumscribed region method according to the contour information of the rivet head to be measured specifically includes:

[0098] Select 4 control points with alternating inner and outer circles and arranged in the same direction from the contour edge points of the rivet head to be measured;

[0099] Connect a straight line L1 between a set of inner circles on the contour edge and two control points on the outer circle, and find the perpendicular bisector B1 of the straight line L1. Connect a straight line L2 between another set of inner circles and two control points on the outer circle, and find the perpendicular bisector B2 of the straight line L2. Calculate the intersection coordinates of B1 and B2, and use the intersection point as the theoretical center of the concentric circles;

[0100] Calculate the roundness error based on the distance between the theoretical center and the above control points ;

[0101] Where: is the maximum distance between the theoretical center and the control points, is the minimum distance between the theoretical center and the control points;

[0102] Select several measurement points near the contour edge. According to the ISO 4292 standard, it is best to select 32 measurement points. If the distances from all measurement points to the theoretical center are within the roundness error, the roundness detection meets the requirements; if there are measurement points whose distances from the theoretical center are outside the roundness error, the roundness detection does not meet the requirements. Therefore, the minimum zone method can accurately calculate the roundness error of the rivet head, and at the same time, the measurement results can reflect the shape fluctuations, which is suitable for evaluating the stability of the manufacturing process.

[0103] As Figure 7 shown, the measurement steps of the triangulation method are as follows:

[0104] Step 1: System calibration: Calibrate the measurement system to determine the precise position and angular relationship between the light source, optical imaging system, etc., as well as the internal parameters of the imaging system, such as focal length, pixel size, etc.

[0105] Step 2: Data acquisition: Industrial camera 19 takes pictures of the front of the rivet head at the riveted joint of the aircraft radome skin, and industrial camera 20 takes pictures of the side of the rivet head.

[0106] Step 3: Model construction: After preprocessing the image such as filtering and denoising, calculate the three-dimensional coordinates of the surface points of the measured object according to the calibration parameters and the triangulation principle, and perform fitting and stitching based on the key frame poses and map point information in the global information of SLAM to obtain the complete three-dimensional information of the surface of the measured object.

[0107] This implementation is for the flatness measurement of the rivet head. Considering that the aircraft rivets are small in size, large in quantity, and mostly made of highly reflective materials, a high-precision vision SLAM vision detection system based on industrial reflection characteristics is used, which includes data preprocessing, rapid construction of the global map, and visual inertial real-time positioning;

[0108] Fusing a visual sensor with an IMU, the IMU provides an initial pose value, which can ensure the state continuity of the area where the reflective coding features are missing. Using the pose of key frames and map point information in the global information as global prior constraints, a visual-inertial tightly coupled joint optimization is carried out with the current image frame having co-visible observation points; introducing a visual residual term and a coded point residual term based on key frames, giving a higher confidence to the residual part of key frames, and using the latest observation information to update the reflective feature points with larger uncertainties in the mapping process in real time to meet continuous photographing and scanning.

[0109] Through the coordinated cooperation among the parts of the automatic detection device, the present invention realizes the automatic detection of rivets at the riveting joints of the aircraft weather radar cover, saves labor costs and time, improves the efficiency and accuracy of rivet installation detection, and can be used for the subsequent standardized and streamlined research on the automatic detection of aircraft radar cover rivet installation; in addition, the device also has functions such as automatic detection, alarm and counting, can obtain the most accurate information during detection to avoid false alarms and missed alarms, greatly saves manpower, optimizes resources more, and creates greater value.

[0110] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative rather than restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. An aircraft radome rivet detection device, characterized in that, Including: A control unit and a detection instrument; The detection instrument acquires pressure value data or image data of the rivet to be measured when contacting the surface of the rivet to be measured; The image data of the rivet to be measured includes: front image data of the rivet head, side image data of the rivet head, and IMU data; The control unit performs flatness detection on the surface of the rivet to be measured according to the pressure value data; The control unit performs flatness detection on the surface of the rivet to be measured according to the side image data of the rivet head and the IMU data; The control unit performs roundness detection on the rivet to be measured according to the front image data of the rivet head.

2. The aircraft radome rivet detection device according to claim 1, wherein The detection instrument is arranged on a circular track through a detection trolley, and the detection trolley drives the detection instrument to move along the circular track to acquire pressure value data or image data of the rivet to be measured when contacting the surface of the rivet to be measured; The circular track includes: a circular frame (7) with an I-shaped cross-section and a circular tooth circulating track (8) concentrically connected thereto. The circular frame (7) and the circular tooth circulating track (8) are provided with an annular groove on the inner circumference of the circular frame (7), and a protruding annular guide rail is designed on the outer circumference of the circular tooth circulating track (8). The size of the annular guide rail matches the annular groove on the inner circumference of the circular frame (7); The detection trolley includes: a receiving plate (9), a first wheel body (14), a pinion (15), a telescopic rod (16), and a second servo motor (18); one end of the receiving plate (9) is rotatably connected to the first wheel body (14) slidably connected to the circular frame (7), the middle of the receiving plate (9) is connected to the second servo motor (18), the second servo motor (18) is connected to the pinion meshing with the circular tooth circulating track (8) through a shaft, and one end of the telescopic rod (16) is connected to the detection trolley and the other end is connected to the detection instrument; When the detection instrument is a pressure sensor (17), the pressure sensor (17) is fixedly connected to the receiving plate (9) through the telescopic rod (16); When the detection instruments are a front-view camera (19) and an auxiliary camera (20), the front-view camera (19) is fixedly connected to the receiving plate (9), the auxiliary camera (20) is placed on the side of the front-view camera (19) through a support rod, and the viewing angle between the front-view camera (19) and the auxiliary camera (20) is 45°.

3. The aircraft radome rivet detection device according to claim 2, wherein, Also including: A slide rail, a base (1), and a second wheel body (2). The base (1) is slidably connected to the slide rail through the connected second wheel body (2). The upper surface of the base (1) is connected to a platform frame (6), and the lower part of the outer side of the circular frame (7) is connected to the platform frame (6).

4. The aircraft radome rivet detection device according to claim 3, wherein, A jacking mechanism is arranged between the base (1) and the platform frame (6). The jacking mechanism includes: a hydraulic strut (3), a first servo motor (4), and a ball screw (5); The first servo motor (4) is installed on the base. One end of the ball screw (5) is connected to the platform frame (6) through a nut pair, and the other end is connected to the first servo motor; The hydraulic struts (3) are symmetrically arranged on both sides of the first servo motor (4), and the pressure pipes of the hydraulic struts (3) are connected to the base, and their piston rods are connected to the platform frame (6).

5. A method for detecting the flatness of aircraft radome rivets, characterized in that Perform detection using the aircraft radome rivet detection device described in any one of claims 1 to 4. The flatness detection method includes: According to the pressure value data when contacting the surface of the rivet to be measured, if the pressure value distribution on the contact surface of the rivet to be measured is uniform, the heights of the rivets to be measured are exactly the same; If the intensity of the pressure signal in the middle of the contact surface of the rivet to be measured is higher than the average value of the adjacent area, the rivet to be measured protrudes; If the intensity of the pressure signal in the middle of the contact surface of the rivet to be measured is lower than the average value of the adjacent area, the rivet to be measured is concave.

6. A method for detecting the flatness of aircraft radome rivets, characterized in that, Perform detection using the aircraft radome rivet detection device described in any one of claims 1 to 4. The flatness detection method includes: Obtain the side image data of the rivet head to be measured and the corresponding IMU data; Store the side image data of the rivet head and the IMU data in chronological order; Preprocess the side image data of the rivet head, and use different polarization angles to obtain the specular reflection feature information of the side of the rivet head, so that the information of the side image data of the rivet head is clear; Preprocess the IMU data, and obtain the local map information of the rivet based on the sliding window method. Use the triangulation method and combine the front image data of the rivet head to be measured obtained by the front camera to construct the global map information of the rivet; According to the global map information of the rivet, combine the chronological order during data acquisition, match the side image of the rivet head with its corresponding front image of the rivet head, and judge whether the side flatness and front roundness of the rivet meet the aviation standards.

7. A method for detecting the roundness of aircraft radome rivets, characterized in that, Perform detection using the aircraft radome rivet detection device described in any one of claims 1 to 4. The roundness detection method includes: According to the obtained front image data of the rivet head to be measured, perform denoising and smoothing processing on the front image data of the rivet head to be measured; Perform grayscale processing on the image of the rivet head to be measured after denoising and smoothing processing, and separate the roundness features of the rivet head to be measured and the image background by binarization of the grayscale processed image; Perform Laplacian edge detection on the separated roundness features of the rivet head to be measured to obtain the contour information of the rivet head to be measured; Evaluate the roundness error of the edge contour of the rivet head to be measured by the minimum circumscribed region method according to the contour information of the rivet head to be measured.

8. The method for detecting the roundness of a radome rivet according to claim 7, wherein The evaluation of the roundness error of the edge contour of the rivet head to be measured by the minimum circumscribed region method according to the contour information of the rivet head to be measured specifically includes: Select 4 control points with alternating inner and outer circles and arranged in the same direction from the contour edge points of the rivet head to be measured; Connect two control points on a set of inner and outer circles of the contour edge to form a straight line L1, and find the perpendicular bisector B1 of the straight line L1. Connect two control points on another set of inner and outer circles to form a straight line L2, and find the perpendicular bisector B2 of the straight line L2. Calculate the intersection coordinates of B1 and B2, and use the intersection point as the theoretical center of the concentric circles; Calculate the roundness error based on the distance between the theoretical center and the above control points ; Wherein: is the maximum distance between the theoretical center and the control point, is the minimum distance between the theoretical center and the control point; Select several measurement points near the contour edge. If the distances from all measurement points to the theoretical center are within the roundness error, the roundness detection meets the requirements. If there are measurement points whose distances from the theoretical center are outside the roundness error, the roundness detection does not meet the requirements.

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