Device, method and robot for detecting loosening of fasteners based on magnetic field variations

Abstract

The present application relates to the device, method and robot based on magnetic field change detection fastener loosening, including carrying platform and bolt sleeve which is sleeved outside fastener nut, the top of bolt sleeve is connected with magnet, the upper surface of magnet is connected with electronic tag, the carrying platform has mechanical arm, the end of mechanical arm is connected with magnetic encoding angle sensor, the detection end of magnetic encoding angle sensor is towards the top surface of bolt sleeve, the mechanical arm with magnetic encoding angle sensor at the end is operated on the track, the bolt sleeve with embedded electronic tag and magnet is installed on the fastener of fastener, when the fastener loosens, the nut produces slight rotation to drive the rotation of bolt sleeve, wherein the magnetic field direction formed by magnet also changes, the bridge formed by GMR element in magnetic encoding sensor will produce sinusoidal wave output with phase difference of 90 degrees, then the output of bridge is sampled by ADC, digital quantization is carried out, finally the real rotation angle value can be calculated by using corresponding function, the loosening of fastener fastener is determined by using the rotation angle value.

Description

Technical Field

[0001] The present invention relates to the technical field of rail fastener detection and maintenance, and in particular to a device, method and robot for detecting fastener loosening based on magnetic field changes. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Fasteners are crucial components of railway tracks, maintaining a tight and stable track connection and playing a significant role in maintaining safe train operation. After installation, fasteners require regular inspections to prevent loosening. Currently, the traditional method for fastener quality testing is manual inspection, which is labor-intensive, inefficient, prone to missed inspections, and requires significant human resources. An emerging fastener quality testing method is machine vision, which utilizes digital cameras to inspect fastener quality. However, this method presents challenges such as difficulty identifying fastener features and poor imaging quality. Consequently, existing technologies are unable to meet the current requirements for fastener quality testing in rail transit. Summary of the Invention

[0004] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides an apparatus, method and robot for detecting the loosening of fasteners based on magnetic field changes. A robotic arm with a magnetically encoded angle sensor at the end runs on a track, and a bolt sleeve with an embedded electronic tag and a magnet is installed on the fastener of the fastener. When the fastener becomes loose, the nut rotates slightly to drive the bolt sleeve to rotate, and the direction of the magnetic field formed by the magnet also changes accordingly. The bridge formed by the GMR element in the magnetically encoded angle sensor will generate a sinusoidal wave output with a phase difference of 90°. The ADC then samples the output of the bridge and performs digital quantization. Finally, the corresponding function can be used to calculate the actual rotation angle value, and the rotation angle value is used to determine the looseness of the fastener.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a device for detecting loose fasteners based on magnetic field changes, comprising: a carrying platform and a bolt sleeve sleeved on the outside of the fastener nut; a magnet is connected to the top of the bolt sleeve, and an electronic tag is connected to the upper surface of the magnet; the carrying platform has a robotic arm, and the end of the robotic arm is connected to a magnetically encoded angle sensor, and the detection end of the magnetically encoded angle sensor faces the top surface of the bolt sleeve.

[0007] The utility model also has a ground workstation which is in communication connection with the magnetic encoding angle sensor and obtains and processes data obtained by the magnetic encoding angle sensor.

[0008] The robotic arm is movably connected to the carrying platform, and the robotic arm can rotate at full angles in the horizontal and vertical directions.

[0009] The cross-sectional shape of the bolt sleeve is consistent with the cross-section of the fastener nut, and the top is provided with a groove for accommodating the magnet and the electronic tag, and the diameter of the groove is the same as the diameter of the fastener bolt.

[0010] The magnet and the electronic tag at the top of the bolt sleeve rotate with the fastener nut.

[0011] The electronic tag saves the position information of the fastener.

[0012] The second aspect of the present application provides a method for detecting the loosening of the fastener based on the above-mentioned device, comprising the following steps:

[0013] The fastener nut drives the rotation of the bolt sleeve, and the magnet and the electronic tag at the top of the bolt sleeve rotate, and the direction of the magnetic field formed by the magnet changes accordingly;

[0014] The magnetic encoding angle sensor obtains the change of the magnetic field, and the sine angle and cosine angle components of the magnetic field signal are obtained after processing to obtain the direction of the magnetic field, and the initial direction of the magnetic field and the changed direction of the magnetic field are compared to obtain the rotation angle of the fastener nut;

[0015] When the rotation angle exceeds the set range, the fastener is loosened.

[0016] After the fastener is installed, the initial direction of the magnetic field is formed by associating the first obtained magnetic field direction and the position information of the fastener to construct a fastener database.

[0017] The third aspect of the present application provides a robot installed with the above-mentioned device: comprising: a robot body connected to a carrying platform, the robot side has a mechanical arm, the robot runs on the track to be detected through the carrying platform, and the magnetic encoding angle sensor at the end of the mechanical arm is located directly above the track fastener.

[0018] After the fastener is installed, the robot runs in the track direction for the first time, and the magnetic field direction obtained by the magnetic encoding angle sensor is associated with the position information of the fastener in the electronic tag to construct a database.

[0019] Compared with the prior art, the above one or more technical solutions have the following beneficial effects:

[0020] 1. High detection efficiency and high precision, the carrying platform drives along the track, the magnetic encoding angle sensor obtains the angle and position information of each group of fastener nut and bolt sleeve, when the fastener is loosened, the fastener nut produces a small rotation to drive the rotation of the bolt sleeve, and the direction of the magnetic field formed by the magnet in the bolt sleeve also changes accordingly, so that it is obtained by the magnetic encoding angle sensor, and the loosening of the fastener and the position of the loosened fastener are quickly determined through at least two detections.

[0021] 2. The process of the magnetic encoding angle sensor acquiring the changing magnetic field does not rely on ambient light. Moreover, when there is oil on the fastener, the magnetic field can still pass through the oil layer and be acquired by the magnetic encoding angle sensor, making the detection effect less susceptible to environmental factors and avoiding the problems existing in the existing technology using image recognition.

[0022] 3. It can be manually controlled through a ground workstation, taking up less human resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0024] Figure 1 is a schematic structural diagram of a fastener loosening detection device provided by one or more embodiments of the present invention;

[0025] Figure 2 is a schematic structural diagram of a fastener loosening detection device provided by one or more embodiments of the present invention arranged on a track;

[0026] Figure 3 is a flow chart of a method for detecting loose rail fasteners provided by one or more embodiments of the present invention;

[0027] In the figure: 1. Screw; 2. Nut; 3. Bolt sleeve; 4. Magnet; 5. Electronic tag; 6. Magnetic encoding angle sensor; 7. Fastener; 8. Carrying platform; 9. Sleeper; 10. Track. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0031] As described in the background technology, the existing technology performs quality inspection on fasteners installed on the track through manual inspection or image recognition to prevent the fasteners from loosening during operation. However, this method takes up more human resources, and the image recognition method is limited by the environment and it is difficult to obtain good recognition results. For example, some fasteners running in tunnels will affect the image recognition effect due to the lack of ambient light.

[0032] Therefore, the following embodiments provide an apparatus, method, and robot for detecting loose fasteners based on magnetic field changes. A carrier platform traveling on a track is provided with a magnetically encoded angle sensor. A bolt sleeve with an embedded electronic tag and a magnet is installed on the fastener of the fastener. When the fastener becomes loose, the nut rotates slightly, driving the bolt sleeve to rotate, wherein the direction of the magnetic field formed by the magnet also changes accordingly. The bridge formed by the GMR element in the magnetically encoded angle sensor will generate a sinusoidal wave output with a phase difference of 90°. The ADC then samples the output of the bridge and performs digital quantization. Finally, the corresponding function can be used to calculate the actual rotation angle value, and the rotation angle value is used to determine the looseness of the fastener.

[0033] Example 1:

[0034] like Figures 1-2 As shown, the device for detecting fastener loosening based on magnetic field changes includes:

[0035] The bolt sleeve 3 is sleeved on the outside of the fastener nut (nut 2), the top of the bolt sleeve 3 is connected to the magnet 4, and the upper surface of the magnet 4 is connected to the electronic tag 5;

[0036] The carrying platform 8 runs on the track 10 and has a mechanical arm, the end of which is connected to the magnetic encoding angle sensor 6 , and the detection end of the magnetic encoding angle sensor 6 faces the top surface of the bolt sleeve 3 .

[0037] The system also includes a ground workstation which is in communication with the magnetic encoding angle sensor 6 and obtains and processes the data acquired by the magnetic encoding angle sensor 6 .

[0038] In this embodiment, the ground workstation uses wireless signals to control the movement and detection of the carrying platform 8, so that the ground workstation can be set in an area far away from the carrying platform, for example, outside a tunnel.

[0039] The robotic arm is movably connected to the carrying platform 8, and the robotic arm can rotate at full angles in the horizontal and vertical directions.

[0040] The cross-section of the bolt sleeve 3 matches that of the fastener nut (nut 2). A recess is located at the top to accommodate the magnet and electronic tag. The recess's diameter matches the diameter of the fastener bolt. In this embodiment, the fastener nut (nut 2) has a hexagonal cross-section, so the bolt sleeve is also hexagonal. The inner diameter of the recess matches the bolt's, ensuring a tight fit and rotational alignment. The bolt sleeve 3 can be made of polypropylene, which is resistant to aging and ensures long-term adherence to the bolt without falling off.

[0041] The carrying platform is controlled by a stepper motor and can perform operations such as braking and speed change, with a speed of up to 20~30km / h.

[0042] The magnetic encoding angle sensor 6 is installed at the end of the extended robotic arm and can rotate with the robotic arm.

[0043] The magnetic encoding angle sensor 6 in this embodiment includes a Hall sensor and a circuit board.

[0044] Specifically:

[0045] Fastener 7 secures rail 10 to sleepers 9 via bolts. When a train travels on rail 10, it causes minute vibrations in fastener 7, loosening the bolts and preventing them from maintaining the rail's stability. This loosening manifests as rotation between the fastener nut and bolt. When bolt sleeve 3 is attached to fastener nut (nut 2), it rotates horizontally with the fastener nut (nut 2). This rotation causes the magnetic field generated by magnet 4 to change direction, which is detected by magnetically encoded angle sensor 6.

[0046] In this embodiment, the magnetically encoded angle sensor 6 can be an Infineon TLE5012B angle sensor. This sensor is based on the GMR (Giant Magneto-Resistance) effect. Four individual GMR elements are connected to form a Wheatstone bridge. Changes in the magnetic field trigger changes in the resistance of the GMR elements, allowing the GMR elements to sense both the sine and cosine components of the applied magnetic field, thereby detecting the direction of the magnetic field. The bolt sleeve 3, which houses the embedded electronic tag and magnet, is in close contact with the nut 2 in the fastener 7. When the nut 2 rotates, the bolt sleeve 3, which is in close contact with the nut, rotates with it. The magnet 4, embedded within the bolt sleeve and in close contact with the nut, rotates in the same direction and angle as the nut, thus changing the direction of the magnetic field it generates.

[0047] The magnetically encoded angle sensor 6 scans the magnet 4 in the bolt sleeve 3, which is attached to the nut 2, to determine the rotation angle. When the bolt sleeve 3 rotates, the bridge formed by the GMR elements in the magnetically encoded angle sensor 6 produces a sinusoidal output with a 90° phase shift. The ADC then samples the bridge output, digitizes it, and uses a corresponding function to calculate the actual rotation angle.

[0048] After the first scan completes and records the magnet angle values ​​for each bolt sleeve 3 with an embedded electronic tag and magnet, a second fastener looseness test is performed at a set interval to obtain the rotation angle values ​​of the bolt sleeve 3 during the second test. Data processing and comparison of the rotation angle values ​​of the nut 2 obtained during the two tests determine the degree of looseness of the fastener 7. Simultaneously, to determine the location of the loosened fastener 7, the bolt sleeve 3 with an embedded electronic tag and magnet is scanned simultaneously with the attached electronic tag 5. The electronic tag stores the fastener's location information, allowing the location of the loosened fastener 7 to be determined.

[0049] Example 2:

[0050] This embodiment provides a method for detecting fastener looseness based on the apparatus described in Embodiment 1, including the following steps:

[0051] The fastener nut drives the bolt sleeve to rotate, and the magnet and electronic tag on the top of the bolt sleeve rotate accordingly, and the direction of the magnetic field formed by the magnet changes accordingly;

[0052] The magnetic encoding angle sensor detects the change in magnetic field, obtains the sine angle and cosine angle components of the magnetic field signal, and then processes them to obtain the magnetic field direction. The initial magnetic field direction and the changed magnetic field direction are compared to obtain the rotation angle of the fastener nut.

[0053] When the rotation angle exceeds the set range, the fastener becomes loose.

[0054] Specifically:

[0055] Step 1: Establish an initial fastener detection database. The extended robotic arm is aligned with the magnetically encoded angle sensor to identify the position of the magnetic bolt sleeve. The rapid transport platform is then controlled to travel along the track to perform the first fastener loosening detection. While traveling along the track, the magnetically encoded angle sensor identifies the current angle of the magnet in the bolt sleeve, which contains an embedded electronic tag and magnet, and transmits this information to the ground workstation for storage. Simultaneously, the electronic tag receiver rapidly identifies the electronic tag in the bolt sleeve, thereby obtaining the location data for the bolt sleeve and the corresponding fastener.

[0056] Step 2: Improve the fastener detection database. When the identification data is inaccurate or missing, the posture of the extended robotic arm can be adjusted to perform all-round identification of the rail fasteners to determine whether the magnetic bolt cap is missing or the magnetic field is weakened.

[0057] Step 3: Establish a fastener secondary inspection database. After the first fastener loosening inspection, conduct a second fastener loosening inspection according to national inspection time regulations. Obtain angle data between the embedded electronic tag and the magnet in the bolt sleeve. Compare the two angle data to determine the looseness of the fastener.

[0058] When a fastener becomes loose, the nut rotates slightly, driving the bolt sleeve. This causes the direction of the magnetic field generated by the magnet to change accordingly. The GMR element in the magnetically encoded angle sensor detects changes in the external magnetic field parallel to its surface and outputs cosine and sine signals. The magnetic field signal undergoes A / D conversion and is then calculated by the sensor's internal CORDIC module for arc tangent to determine the required angle. Finally, the magnetic field angle information is output via various signal protocols, allowing the rotation angle to be used to determine the looseness of the fastener.

[0059] The detection efficiency and accuracy are high, allowing the platform to travel quickly along the track. The magnetically encoded angle sensor and electronic tag receiver quickly obtain the angle and position information of the bolt cap. By comparing the two, it can quickly determine whether the fastener is loose and the location of the loose fastener. In addition, the magnetically encoded angle sensor has high angle recognition accuracy, with a resolution of up to 0.01°.

[0060] The detection effect is not limited by environmental factors. Tunnels are dimly lit, and image recognition methods require a sufficiently bright light source for the camera to ensure accurate photo detection. This method, however, is not limited by lighting conditions. Furthermore, the presence of oil on fasteners can lead to unclear edges on the hexagonal nuts, hindering the recognition and processing of contour features by digital photo detection techniques. This detection method also circumvents this problem.

[0061] The inspection is less manpower-intensive and intelligent, and can be manually controlled using a ground workstation, occupying less human resources.

[0062] Example 3:

[0063] This embodiment provides a robot installed with the device described in Example 1, including: a robot body connected to a carrying platform, a robotic arm on the side of the robot, the robot runs on the track to be tested through the carrying platform, and the magnetic encoding angle sensor at the end of the robotic arm is located directly above the track fastener.

[0064] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A device for detecting loose fasteners based on magnetic field changes, characterized in that: The system comprises a carrying platform and a bolt sleeve that fits over the outside of a fastener nut; a magnet is connected to the top of the bolt sleeve, and an electronic tag is connected to the upper surface of the magnet; the carrying platform has a robotic arm, the end of which is connected to a magnetically encoded angle sensor, with the detection end of the magnetically encoded angle sensor facing the top surface of the bolt sleeve; the magnetically encoded angle sensor uses GMR (giant magnetoresistive) magnetic sensing elements. Four separate GMR elements are connected to form a Wheatstone bridge. Changes in the magnetic field induce changes in the GMR resistance, causing the GMR elements to sense the sine and cosine components of the applied magnetic field. The corresponding function is used to calculate the rotation angle value, which is then used to determine whether the fastener is loose. The cross-sectional shape of the bolt sleeve is consistent with that of the fastener nut, and a groove for accommodating the magnet and the electronic tag is provided on the top, and the diameter of the groove is the same as that of the fastener bolt; It also has a ground workstation, which is in communication with the magnetic encoding angle sensor and obtains and processes data obtained by the magnetic encoding angle sensor; The carrying platform is controlled by a stepping motor; The ground workstation obtains and processes data acquired by the magnetic encoding angle sensor, specifically including: Step 1: Establish an initial fastener detection database, adjust the extended robotic arm to a posture where the magnetic encoding angle sensor can easily identify the magnetic bolt sleeve, and control the rapid transport platform to travel along the track to perform the first fastener loosening detection. While traveling along the track, the magnetic encoding angle sensor can identify the current angle information of the magnet in the bolt sleeve with an embedded electronic tag and magnet and transmit it to the ground workstation for storage; at the same time, the electronic tag receiver quickly identifies the electronic tag in the bolt sleeve, thereby obtaining the positioning data of the bolt sleeve and the corresponding fastener; Step 2: Improve the fastener detection database. When inaccurate or missing data is detected, the extended robotic arm can be adjusted to perform a full-scale identification of the rail fastener to determine whether the magnetic bolt cap is missing or the magnetic field is weakened. Step three, establish a fastener secondary detection database, perform a second fastener loosening detection after the first fastener loosening detection, obtain the angle data of the magnet in the bolt sleeve with the embedded electronic tag and the magnet, and compare the two angle data to determine the looseness of the fastener.

2. The device for detecting fastener loosening based on magnetic field changes according to claim 1, wherein: The robotic arm is movably connected to the carrying platform, and the robotic arm can rotate at full angles in the horizontal and vertical directions.

3. The device for detecting fastener loosening based on magnetic field changes according to claim 2, wherein: The magnet and the electronic tag on the top of the bolt sleeve rotate along with the fastener nut.

4. The device for detecting fastener loosening based on magnetic field changes according to claim 2, wherein: The electronic tag stores the location information of the fastener.

5. A method for detecting fastener loosening based on the device according to any one of claims 1 to 4, characterized in that: The following steps are involved: The fastener nut drives the bolt sleeve to rotate, and the magnet and electronic tag on the top of the bolt sleeve rotate accordingly, and the direction of the magnetic field formed by the magnet changes accordingly; The magnetic encoding sensor detects the change in magnetic field, obtains the sine angle and cosine angle components of the magnetic field signal, and then processes them to obtain the magnetic field direction. The initial magnetic field direction and the changed magnetic field direction are compared to obtain the rotation angle of the fastener nut. When the rotation angle exceeds the set range, the fastener becomes loose.

6. The method for detecting fastener loosening based on magnetic field changes according to claim 5, wherein: After the fastener is installed, the initial magnetic field direction is constructed by associating the magnetic field direction obtained for the first time with the fastener position information.

7. Fastener loosening robot, including: The device according to any one of claims 1 to 4 is installed.

8. The fastener loosening detection robot according to claim 7, wherein: After the fasteners are installed, the robot runs along the track for the first time. The magnetic field direction obtained by the magnetic encoding angle sensor is associated with the fastener position information in the electronic tag to build a database.

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