A bolt loosening angle sensor and monitoring method

Abstract

This invention provides a bolt loosening angle sensor and monitoring method, belonging to the field of fastener condition monitoring technology. The sensor has dual channels for detecting the angular position of the bolt and nut respectively, with a magnetic shielding component between the two channels and a clearance structure on the housing. The main control circuit performs digital crosstalk compensation on the acquired magnetic field signal, calculates the loosening angle, and determines the breakage / detachment state based on the signal amplitude, directly outputting the monitoring result. This invention achieves high-precision, high-reliability online monitoring and possesses a fault self-diagnosis function through a crosstalk resistance mechanism combining independent dual-channel detection, physical shielding, and digital compensation, as well as intelligent edge processing.

Description

Technical Field

[0001] This invention relates to the field of fastener condition monitoring technology, and more specifically, to a bolt loosening angle sensor and monitoring method. Background Technology

[0002] Bolted connections, as a critical fastening method, are widely used in wind turbines, bridge steel structures, high-pressure vessels, and heavy machinery. Loosening of bolts not only weakens the overall rigidity and load-bearing capacity of the structure but can also lead to catastrophic safety accidents. Therefore, high-precision online monitoring of the tightness of bolted connections is of paramount importance for ensuring the safe operation of critical equipment.

[0003] Most existing magnetoelectric bolt loosening sensors employ a scheme where a single magnetic ring is mounted at one end of the bolt or nut, along with a set of Hall effect sensors for detection. This approach can only measure the overall relative rotation between the bolt and nut, and cannot distinguish whether the loosening originates from the bolt's own rotation or the nut's rotation. This lack of information makes it difficult to accurately pinpoint the specific source of loosening during troubleshooting and maintenance decisions, thus limiting failure analysis.

[0004] To achieve independent detection of bolts and nuts, some solutions have proposed a structure using upper and lower double magnetic rings and a double-layer detection element. However, in many practical applications, such as when the bolt end protrudes only a short distance, the distance between the upper and lower magnetic rings is forced to be very close, resulting in severe crosstalk between their magnetic fields. Simply adding a single layer of physical shielding between the two detection elements is insufficient to effectively attenuate this strong crosstalk, leading to significant errors in angle calculation and failing to meet the requirements of high-precision monitoring.

[0005] Furthermore, existing technologies face other challenges. For example, in scenarios with densely packed bolts, such as flanges, the traditional configuration of "one bolt per sensor" results in a massive number of sensors, leading to not only a huge workload for installation but also high overall system costs. Simultaneously, many solutions require uploading raw sensor data to a host computer or cloud server for complex angle calculations. This places high demands on data transmission bandwidth and increases the computational burden on backend servers, hindering large-scale, low-cost deployment and application.

[0006] More importantly, most existing sensors only focus on angular changes and lack the ability to effectively identify more serious physical structural damage such as broken or detached bolts or nuts, meaning they cannot determine their physical integrity. Meanwhile, the complex electromagnetic environment of industrial sites, especially the presence of far-field DC magnetic fields, can easily interfere with Hall sensor measurements. Existing suppression methods often require precise parameter calibration of the sensor, reducing the system's environmental adaptability and long-term operational reliability. Summary of the Invention

[0007] The purpose of this invention is to provide a bolt loosening angle sensor and monitoring method, which aims to solve the problems mentioned in the background art.

[0008] This invention is implemented as follows: a bolt loosening angle sensor, comprising:

[0009] Sensor body;

[0010] A dual-channel sensing assembly is disposed within the sensor body, including a first sensing channel for detecting the angular position of a bolt and a second sensing channel for detecting the angular position of a nut.

[0011] A magnetic shielding component is disposed between the first sensing channel and the second sensing channel to attenuate magnetic field crosstalk between the channels;

[0012] The housing of the sensor body is provided with a clearance structure, which is used to accommodate at least a part of the nut when the nut is loosened and rotated, so as to keep the housing and the rotating nut in a non-contact state.

[0013] The main control circuit is disposed within the sensor body. The main control circuit is configured to perform digital crosstalk compensation on the magnetic field signals collected by the first sensing channel and the second sensing channel, calculate the loosening angle information of the bolt and / or nut, and output the loosening angle information. The main control circuit is also configured to determine the physical integrity status of the bolt or nut based on the amplitude of the magnetic field signal and output the corresponding diagnostic result.

[0014] Optionally, the first sensing channel includes a first magnetic mark for connection with a bolt and a first sensor array for detecting the magnetic field of the first magnetic mark, and the second sensing channel includes a second magnetic mark for connection with a nut and a second sensor array for detecting the magnetic field of the second magnetic mark; the magnetic shielding assembly is located between the first sensor array and the second sensor array.

[0015] Optionally, the magnetic shielding assembly is composed of multiple layers of silicon steel sheets or soft magnetic sheets stacked together; the first sensor array is an upper Hall sensor array, the second sensor array is a lower Hall sensor array, and the upper Hall sensor array and the lower Hall sensor array are respectively disposed on opposite sides of the magnetic shielding assembly.

[0016] Optionally, the main control circuit is configured to calculate the crosstalk component applied to the other sensor array based on a preset crosstalk model using the measured magnetic field signal of one of the first sensor array or the second sensor array, and to eliminate the crosstalk component from the measured signal of the other sensor array.

[0017] Optionally, the crosstalk model is a transmission matrix model. The main control circuit calculates the crosstalk component applied to another sensing channel based on the measured magnetic field signal of one sensing channel using a pre-calibrated transmission matrix, and subtracts the crosstalk component from the measured signal of the other sensing channel.

[0018] Optionally, the main control circuit is further configured to monitor the peak amplitude of the magnetic field signal, determine whether the amplitude is lower than a preset threshold, and output a diagnostic result that the bolt or nut has broken and fallen off when it is lower than the preset threshold.

[0019] Optionally, the main control circuit is further configured to use the sampling signals of multiple sensing elements in the first sensor array and / or the second sensor array to calculate the DC bias component introduced by the ambient far-field magnetic field through least squares estimation or analytical operation, and to eliminate the DC bias component from the sampling signals.

[0020] When the number of sensing elements is at least four, the main control circuit incorporates the DC bias component as a parameter to be estimated into the least squares model, and calculates the estimated value of the angle-related parameters and the DC bias component in one step through least squares estimation.

[0021] Optionally, the sensor body integrates at least two sets of dual-channel sensing components. Each set of dual-channel sensing components is used to monitor a bolt connection pair. The main control circuit processes the signals collected by each set of dual-channel sensing components and outputs the loosening angle information of each bolt connection pair.

[0022] Optionally, the bottom of the sensor body is provided with a magnetic mounting component for adsorbing and fixing the sensor body to the metal surface where the bolt connection is located; the clearance structure on the housing is a cylindrical clearance space, the inner diameter of which is larger than the outer diameter of the maximum sweep profile when the nut rotates.

[0023] Another object of the present invention is a bolt loosening monitoring method, employing the aforementioned bolt loosening angle sensor, comprising:

[0024] The magnetic field signals corresponding to the bolt angle position and nut angle position are collected by the first sensing channel and the second sensing channel, respectively.

[0025] Based on a preset crosstalk model, the magnetic field signal collected by this sensing channel is digitally crosstalk compensated using the signal from the opposing sensing channel to obtain the compensated magnetic field signal.

[0026] The loosening angle of the bolt and / or nut is calculated based on the compensated magnetic field signal;

[0027] Furthermore, during the calculation of the loosening angle, the peak amplitude of the magnetic field signal is used to determine whether the bolt or nut has broken or fallen off.

[0028] The sensor body directly outputs the diagnostic results of the loosening angle and / or breakage / detachment.

[0029] The bolt loosening angle sensor and monitoring method provided by this invention have the following beneficial effects:

[0030] First, the dual-channel sensing design enables independent monitoring of the loosening angles of both bolts and nuts, providing richer dimensions and more reliable data for fault analysis and precise maintenance. Second, the dual anti-crosstalk mechanism of "physical shielding + digital compensation" effectively solves the problem of magnetic field crosstalk in the close-range dual magnetic ring scheme, ensuring high-precision angle measurement even when the magnetic ring spacing is extremely small.

[0031] Furthermore, this invention integrates all core algorithms into the sensor's internal main control circuit, achieving intelligent edge computing. The sensor directly outputs the final angle and state results, significantly reducing the requirements for data transmission bandwidth and backend server computing power, thus creating conditions for large-scale, low-cost deployment. Simultaneously, by monitoring signal amplitude, it achieves online self-diagnosis, enabling timely warnings of serious faults such as bolt breakage and detachment, improving system safety. The avoidance structure design on the housing, magnetic installation, and flexible communication interface options collectively enhance the sensor's ease of installation, measurement stability, and scene adaptability.

[0032] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0033] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0034] Figure 1 This is a flowchart of the bolt loosening monitoring method in an embodiment of the present invention.

[0035] Figure 2 This is a schematic diagram of the overall assembly of the bolt loosening sensor in an embodiment of the present invention.

[0036] Figure 3 This is a schematic diagram of the internal structure of the sensor body in an embodiment of the present invention.

[0037] Figure 4 This is a three-dimensional structural diagram of the Hall sensor assembly in an embodiment of the present invention.

[0038] Figure 5This is a schematic diagram of the front view structure of the Hall sensor assembly in an embodiment of the present invention.

[0039] Figure 6 This is a schematic diagram of the structure and installation method of the bolt magnetic ring in an embodiment of the present invention.

[0040] Figure 7 This is a schematic diagram of the structure and installation method of the nut magnetic ring in an embodiment of the present invention.

[0041] Figure 8 This is a schematic diagram illustrating the application of the "one-to-two" integrated monitoring scheme in an embodiment of the present invention.

[0042] Figure 9 This is a schematic diagram of the internal structure of the "one-to-two" sensor body in an embodiment of the present invention.

[0043] In the diagram: 1-Sensor body, 11-Main control circuit, 12-Hall sensor assembly, 121-Upper Hall sensor array, 122-Lower Hall sensor array, 123-Magnetic shielding assembly, 13-Pot magnet, 14-Cylindrical clearance space, 2-Bolt magnetic ring, 22-Bolt, 23-First N / S magnetic pole, 3-Nut magnetic ring, 32-Nut, 33-Second N / S magnetic pole. Detailed Implementation

[0044] To address the problems in existing bolt loosening monitoring technologies, such as the inability to distinguish between the independent loosening amounts of bolts and nuts, low measurement accuracy due to short-range magnetic crosstalk, high deployment costs, and inability to identify breakage and detachment, this invention provides a high-precision, multifunctional, and easily deployable bolt loosening angle sensor and its monitoring method. In the context of this invention, some core terms have specific meanings. "Dual-channel sensing assembly" refers to an integrated sensing unit containing two independent sensing channels, used to detect the angular positions of the bolt and nut respectively. "First sensing channel" and "second sensing channel" refer to the independent signal paths used to detect the angular positions of the bolt and nut, respectively; each channel typically consists of a magnetic marker and a sensor array. "Physical integrity state" specifically refers to whether the bolt or nut has experienced physical structural damage such as breakage or detachment, causing it to disappear from its original position. The core idea of ​​this invention is to solve the magnetic crosstalk problem through a dual mechanism combining "physical shielding" and "digital compensation," and to adopt an "edge-end intelligence" architecture, performing all complex calculations locally on the sensor, thereby achieving high-precision, high-reliability, and easily scalable monitoring.

[0045] The technical solution of the present invention will now be described in detail. (Refer to...) Figure 1The flowchart shown illustrates a bolt loosening monitoring method provided by this invention. First, magnetic field signals corresponding to the angular positions of the bolt and nut are independently acquired through a first sensing channel and a second sensing channel. These two channels are physically separate, each performing non-contact measurements on its corresponding magnetic marker, thus providing original and independent signal sources for subsequent differentiation between bolt rotation and nut loosening. This step is fundamental to achieving a comprehensive condition assessment of the bolted connection pair, ensuring the acquisition of differentiated dynamic information from the source.

[0046] After acquiring the raw magnetic field signal, this method performs an important signal preprocessing step before performing the core angle calculation. Specifically, before performing digital crosstalk compensation on the acquired magnetic field signal, the method also utilizes the signal redundancy of the first sensing channel and / or the second sensing channel to calculate and eliminate DC bias interference introduced by the ambient far-field magnetic field through an algorithm. Industrial environments often have background magnetic fields generated by various motors, cables, etc., which superimpose a DC bias component onto the sensor signal, severely affecting the accuracy of angle calculation. This step utilizes the sampling redundancy information of multiple sensing elements in the sensor array to accurately calculate this DC bias component using an algorithm and subtract it from the raw signal, thereby effectively improving the sensor's anti-interference capability and measurement robustness in complex electromagnetic environments.

[0047] Next, the method proceeds to the digital crosstalk compensation step. Since the magnetic markings on the bolt and nut are spatially close, the magnetic field of one channel inevitably leaks to the sensor in the other channel, creating crosstalk. To address this, the method performs digital crosstalk compensation on the acquired magnetic field signal within the sensor body, based on a pre-defined crosstalk model and signals from the opposing sensing channel, to obtain a compensated magnetic field signal. Specifically, this digital crosstalk compensation step includes: based on a pre-calibrated transmission matrix, using the measured magnetic field signal from either the first or second sensing channel, calculating the crosstalk component applied to the other sensing channel, and subtracting this crosstalk component from the measured signal of the other sensing channel. This method can accurately quantify and eliminate residual crosstalk remaining after physical shielding, obtaining a pure magnetic field signal that only reflects the position of each magnetic marking, which is a key step in achieving high-precision angle measurement.

[0048] After obtaining a clean magnetic field signal, the method can perform accurate angle calculation. Based on the compensated magnetic field signal, the loosening angle of the bolt and / or nut is calculated. This calculation process utilizes the periodicity of magnetic field strength changing with angle, and through a specific phase demodulation algorithm, converts the magnetic field signal vector into an accurate angle value. Since the signal has been preprocessed and crosstalk compensated, the calculated angle value can accurately reflect the amount of rotation of the bolt or nut relative to the initial tightening position, thereby achieving quantitative monitoring of the loosening state.

[0049] The method of this invention not only monitors the angle but also has the ability to diagnose extreme faults. During the calculation of the loosening angle, the method also diagnoses whether the bolt or nut has broken or fallen off based on the amplitude of the obtained magnetic field signal, i.e., it determines its physical integrity status. Specifically, this diagnostic step includes: monitoring the peak amplitude of the magnetic field signal obtained during the calculation of the loosening angle; and comparing the peak amplitude with a preset threshold, determining whether the corresponding bolt or nut has broken or fallen off based on the comparison result. When the bolt or nut breaks and falls out of its original position, its corresponding magnetic mark also disappears, causing a sharp drop in the amplitude of the magnetic field signal detected by the sensor. By monitoring this amplitude in real time, once it falls below a preset safety threshold, the system can determine that a serious physical failure such as breakage or falling off has occurred, thus providing additional protection for equipment safety.

[0050] Finally, the method of this invention emphasizes the edge-end intelligent processing architecture. All the above steps, including signal acquisition, preprocessing, crosstalk compensation, angle calculation, and status diagnosis, are completed within the computing unit inside the sensor body. Ultimately, the sensor body directly outputs the diagnostic results of the loosening angle and / or breakage / detachment. This design moves complex computational tasks forward to the sensor end, resulting in a processed, high-information-density final result rather than a large amount of raw waveform data. This significantly reduces the requirements for data transmission bandwidth and backend server computing power, simplifies the system architecture, and lowers overall deployment and maintenance costs, making it particularly suitable for large-scale, distributed monitoring applications.

[0051] To achieve the above method, the present invention provides a bolt loosening angle sensor. For example... Figure 2 As shown, when applied to a bolted connection, the sensor's overall structure includes a bolt loosening sensor body 1, a bolt magnetic ring 2 associated with the bolt, and a nut magnetic ring 3 associated with the nut. The sensor body 1 is magnetically fixed to the metal plane of the bolted connection, while its internal sensing structure is aligned with the space between the bolt magnetic ring 2 and the nut magnetic ring 3 for non-contact measurement.

[0052] like Figure 3As shown, the sensor body 1 houses all the components that enable its full functionality. Inside, there is a main control circuit 11, which acts as the "brain" of the entire sensor, responsible for executing all the algorithms and control logic described above. A magnetic mounting mechanism, specifically one or more magnets 13 in this embodiment, is located at the bottom of the sensor body 1. Its strong magnetic attraction firmly adheres the sensor body 1 to a metal surface, achieving quick and non-destructive installation without drilling or fasteners. This installation method is not only convenient but also ensures the stability of the measurement reference.

[0053] The housing of sensor body 1 has undergone special design. For example... Figure 3 As shown, its configuration has a geometric feature, specifically a cylindrical clearance 14. This clearance is located on the side of the housing near the bolted connection, and its inner diameter is designed to be larger than the sweep profile formed when the nut loosens and rotates. This design ensures that even if the nut loosens and rotates significantly, its outer edge will not make any physical contact or squeeze with the housing of the sensor body 1, thereby fundamentally avoiding the problem of sensor position displacement and measurement reference failure due to collision, and ensuring the reliability and accuracy of long-term monitoring.

[0054] The core measurement function of the sensor is implemented by a dual-channel sensing component, specifically a Hall sensor component 12 in this embodiment, which is connected to the main control circuit 11 via a ribbon cable. Figure 4 and Figure 5 As shown, the Hall sensor assembly 12 has a layered internal structure, including an upper Hall sensor array 121 and a lower Hall sensor array 122. The sensing surface of the upper Hall sensor array 121 faces upward and is used to detect the bolt angle position; the sensing surface of the lower Hall sensor array 122 faces downward and is used to detect the nut angle position. These two arrays together form the basis of the first and second sensing channels for independently acquiring signals.

[0055] To suppress mutual interference between the two channels, a magnetic shielding assembly 123 is provided between the upper Hall sensor array 121 and the lower Hall sensor array 122. This magnetic shielding assembly 123 is composed of multiple layers of high-permeability materials, such as multiple layers of silicon steel sheets or soft magnetic sheets, and is used to attenuate the interfering magnetic field penetrating from the opposing magnetic rings. This physical shielding design is the first line of defense against magnetic crosstalk between channels, capable of diverting or attenuating most of the crosstalk magnetic field, creating favorable working conditions for subsequent digital compensation algorithms.

[0056] The sensor's first and second sensing channels respectively include a magnetic marker and a sensor array. For example... Figure 6As shown, the magnetic marker of the first sensing channel is a bolt magnetic ring 2, with a blind hole with an internal thread at its lower end. During installation, the bolt magnetic ring 2 is tightened onto the upper end of the bolt 22 until the bottom of the blind hole abuts against the top surface of the bolt, thereby achieving synchronous rotation with the bolt. Figure 7 As shown, the magnetic marker of the second sensing channel is a nut magnetic ring 3, which has a through hole in its center. During installation, it is sleeved on the bolt rod and fixed to the upper end face of the nut 32 by its own magnetic force, thereby achieving synchronous rotation with the nut. Both magnetic rings have embedded first N / S magnetic poles 23 and second N / S magnetic poles 33 arranged alternately along the circumference to generate a magnetic field that changes periodically with the angle.

[0057] The main control circuit 11 is configured to execute a series of algorithms. First, it is configured to calculate and eliminate crosstalk components in the signal of its own sensing channel based on a preset crosstalk model and signals from the opposing sensing channel. In a preferred embodiment, the main control circuit 11 is configured to calculate the crosstalk components applied to the other sensor array based on a transmission matrix model, using the measured magnetic field signal of one of the sensor arrays in the first or second sensor array, and subtract the crosstalk components from the measured signal of the other sensor array. This achieves accurate digital cancellation of residual crosstalk.

[0058] Secondly, the main control circuit 11 is configured to determine the physical integrity status of the bolt or nut by analyzing the amplitude of the magnetic field signal. Specifically, the main control circuit 11 determines the physical integrity status by monitoring the peak amplitude of the magnetic field obtained during angle calculation and determining whether the amplitude is lower than a preset threshold. This multi-functional design, without increasing any hardware costs, endows the sensor with self-diagnostic capabilities for serious faults such as breakage and detachment, greatly improving the safety of the system.

[0059] Furthermore, the main control circuit 11 is configured to utilize the signal redundancy of the first sensor array and / or the second sensor array to calculate and eliminate DC bias interference introduced by the ambient far-field magnetic field through an algorithm. This function enables the sensors to adapt to various complex industrial electromagnetic environments, ensuring the accuracy of the measurement results. Finally, the main control circuit 11 is configured to process all raw sensor signals to directly output the final angle and status information, realizing edge intelligent calculation and simplifying the architecture of the entire monitoring system.

[0060] The core algorithms involved in the aforementioned method will be explained in more detail below. Regarding the angle calculation algorithm, its basic principle is based on multi-Hall sampling phase demodulation of a circumferential sinusoidal magnetic field. Assuming the peak value of the sinusoidal magnetic field generated by a single magnetic ring is B0, and the Hall array contains N sensors, the position and phase of the k-th sensor are... When the magnetic ring rotates relative to the Hall array by an angle At that time, the ideal output of the k-th Hall sensor is: .

[0061] When the Hall array uses N=3 sensors, a universal analytical solution can be used. In this case, it is not necessary to pre-calibrate the electrical phase spacing between adjacent sensors. The phase interval can be directly obtained by performing trigonometric function transformations on the outputs B1, B2, and B3 of the three sensors: .get Then, the full-phase analytical solution for the loosening angle can be further obtained: ,in It is the arctangent function in the four quadrants. Simultaneously, the peak magnetic field value can also be solved: This analytical solution method requires minimal computation and does not require pre-calibration of parameters, making it ideal for embedded systems.

[0062] When the Hall array contains N>3 sampling points, linear least squares estimation can be used to suppress random noise and improve measurement accuracy. The output model is expanded into a linear form: The parameter to be estimated is and Write it in matrix form. Where B is the sampling vector, and H is the position and phase. The observation matrix is ​​formed. According to the least squares criterion, the optimal parameter estimate is: Ultimately, the loosening angle changed from... The estimated peak magnetic field value is obtained. .

[0063] Regarding the algorithm for suppressing environmental DC magnetic field interference, when a DC bias component exists... At that time, the sensor output becomes For the case of N=3, if the phase interval is pre-calibrated... The DC bias can then be solved analytically. By performing algebraic operations on the outputs of the three sensors, B0 and... We obtain the closed-form solution for DC bias: Find out Then, subtract it from each sampled value to obtain the pure signal for angle calculation.

[0064] When the Hall array contains N ≥ 4 sampling points, adaptive debiasing can be achieved without pre-calibrating the phase interval. In this case, DC bias is applied. As the third parameter to be estimated, it is included in the least squares model. The linear model becomes... Construct an N×3 observation matrix H, where the elements in the k-th row are... Through least squares estimation This method can obtain the optimal solutions for angle-related parameters and DC bias in one go. It utilizes sampling redundancy, making it more robust.

[0065] The core of the magnetic crosstalk compensation algorithm is to establish a crosstalk transmission matrix model. Let the measured output vectors of the lower and upper layer Hall arrays be respectively... and The process by which the magnetic field of a magnetic ring passes through the magnetic shielding assembly to reach the opposing sensor array can be described by an N×N transfer matrix T. Therefore, the crosstalk magnetic field generated by the nut magnetic ring at the upper Hall array is TB. Then, the pure magnetic field signal of the bolt magnetic ring at the upper array is the measured value minus the crosstalk value. Similarly, the pure magnetic field of the nut magnetic ring at the lower array is: The compensated and By substituting the values ​​into the angle calculation algorithm, the high-precision bolt and nut loosening angles can be obtained.

[0066] The value of the transmission matrix T is related to the specific structural parameters of the sensor and can be determined in advance through a one-time calibration experiment. For example, under the condition of installing only a single-sided magnetic ring, the outputs of the upper and lower Hall arrays are collected simultaneously, and all elements of T can be obtained through linear fitting. Experimental verification shows that when using a magnetic shielding assembly composed of three layers of silicon steel sheets, the amplitude attenuation factor of physical shielding can reach more than 10 times (i.e., the maximum principal singular value of T is less than 0.1). After secondary cancellation by this digital compensation algorithm, the remaining crosstalk error can be further suppressed to less than 1% of the original value. This allows the sensor to maintain extremely high angle measurement accuracy even under harsh conditions with extremely small magnetic ring spacing (e.g., short bolt extension length).

[0067] This invention also provides a variety of flexible configuration schemes to adapt to different application scenarios. For example... Figure 8 and Figure 9 As shown, in an extended embodiment, at least two independent Hall sensor assemblies 12 can be integrated inside the sensor body 1. During installation, this "one-to-many" sensor body 1 is placed in the central area of ​​multiple bolted connections, so that each set of Hall sensor assemblies 12 inside is aligned with one bolted connection for monitoring. The main control circuit 11 processes the data from all channels uniformly and independently calculates and outputs the loosening state of each bolt. This "one-to-many" integrated monitoring scheme can significantly reduce the number of sensors required in situations with dense bolts, such as flanges, thereby significantly reducing hardware costs and installation complexity.

[0068] Furthermore, this sensor supports a simplified configuration mode with a single magnetic ring. In cost-sensitive scenarios or where only the overall looseness status needs to be determined, one of the magnetic rings can be omitted. For example, only the nut magnetic ring 3 and the sensor body 1 can be retained. In this case, the lower Hall sensor array 122 is dedicated to monitoring the looseness angle of the nut, while the upper array and part of the magnetic shielding structure can be omitted, thereby reducing costs. Conversely, only the bolt magnetic ring 2 can be retained for monitoring. This flexible and adjustable configuration allows users to make the most suitable trade-off between functionality, accuracy, and cost.

[0069] To adapt to different industrial environments, the sensor body 1 offers a variety of communication interface options. For example, it can be configured with a wired RS485 or CAN bus interface to meet the needs of long-distance, high-reliability industrial networking. Simultaneously, it can be configured with a wireless Bluetooth or LoRa communication module for short-range debugging or long-range low-power wireless networking, solving data transmission problems in scenarios where wiring is difficult. These flexible communication interface designs greatly enhance the product's adaptability to various scenarios.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A bolt loosening angle sensor, characterized in that, include: Sensor body; A dual-channel sensing assembly is disposed within the sensor body, including a first sensing channel for detecting the angular position of a bolt and a second sensing channel for detecting the angular position of a nut. A magnetic shielding component is disposed between the first sensing channel and the second sensing channel to attenuate magnetic field crosstalk between the channels; The housing of the sensor body is provided with a clearance structure, which is used to accommodate at least a part of the nut when the nut is loosened and rotated, so as to keep the housing and the rotating nut in a non-contact state. The main control circuit is disposed within the sensor body. The main control circuit is configured to perform digital crosstalk compensation on the magnetic field signals collected by the first sensing channel and the second sensing channel, calculate the loosening angle information of the bolt and / or nut, and output the loosening angle information. The main control circuit is also configured to determine the physical integrity status of the bolt or nut based on the amplitude of the magnetic field signal and output the corresponding diagnostic result.

2. The bolt loosening angle sensor according to claim 1, characterized in that, The first sensing channel includes a first magnetic mark for connection with a bolt and a first sensor array for detecting the magnetic field of the first magnetic mark; the second sensing channel includes a second magnetic mark for connection with a nut and a second sensor array for detecting the magnetic field of the second magnetic mark; the magnetic shielding assembly is located between the first sensor array and the second sensor array.

3. The bolt loosening angle sensor according to claim 2, characterized in that, The magnetic shielding assembly is composed of multiple layers of silicon steel sheets or soft magnetic sheets stacked together; the first sensor array is an upper Hall sensor array, the second sensor array is a lower Hall sensor array, and the upper Hall sensor array and the lower Hall sensor array are respectively disposed on opposite sides of the magnetic shielding assembly.

4. The bolt loosening angle sensor according to claim 2, characterized in that, The main control circuit is configured to calculate the crosstalk component applied to the other sensor array based on a preset crosstalk model, using the measured magnetic field signal of one of the first sensor array or the second sensor array, and to eliminate the crosstalk component from the measured signal of the other sensor array.

5. The bolt loosening angle sensor according to claim 4, characterized in that, The crosstalk model is a transmission matrix model. The main control circuit calculates the crosstalk component applied to another sensing channel using the measured magnetic field signal of one sensing channel based on the pre-calibrated transmission matrix, and subtracts the crosstalk component from the measured signal of the other sensing channel.

6. The bolt loosening angle sensor according to claim 1, characterized in that, The main control circuit is also configured to monitor the peak amplitude of the magnetic field signal, determine whether the amplitude is lower than a preset threshold, and output a diagnostic result that the bolt or nut has broken and fallen off when it is lower than the preset threshold.

7. The bolt loosening angle sensor according to claim 2, characterized in that, The main control circuit is also configured to use the sampling signals of multiple sensing elements in the first sensor array and / or the second sensor array to calculate the DC bias component introduced by the ambient far-field magnetic field through least squares estimation or analytical operation, and to eliminate the DC bias component from the sampling signals. When the number of sensing elements is at least four, the main control circuit incorporates the DC bias component as a parameter to be estimated into the least squares model, and calculates the estimated value of the angle-related parameters and the DC bias component in one step through least squares estimation.

8. The bolt loosening angle sensor according to claim 1, characterized in that, The sensor body integrates at least two sets of dual-channel sensing components. Each set of dual-channel sensing components is used to monitor a bolt connection pair. The main control circuit processes the signals collected by each set of dual-channel sensing components and outputs the loosening angle information of each bolt connection pair.

9. The bolt loosening angle sensor according to claim 1, characterized in that, The bottom of the sensor body is provided with a magnetic mounting component for adsorbing and fixing the sensor body to the metal surface of the bolt connection pair; the clearance structure on the housing is a cylindrical clearance space, the inner diameter of which is larger than the outer diameter of the maximum sweep profile when the nut rotates.

10. A method for monitoring bolt loosening, characterized in that, The bolt loosening angle sensor as described in any one of claims 1 to 9 includes: The magnetic field signals corresponding to the bolt angle position and nut angle position are collected by the first sensing channel and the second sensing channel, respectively. Based on a preset crosstalk model, the magnetic field signal collected by this sensing channel is digitally crosstalk compensated using the signal from the opposing sensing channel to obtain the compensated magnetic field signal. The loosening angle of the bolt and / or nut is calculated based on the compensated magnetic field signal; Furthermore, during the calculation of the loosening angle, the peak amplitude of the magnetic field signal is used to determine whether the bolt or nut has broken or fallen off. The sensor body directly outputs the diagnostic results of the loosening angle and / or breakage / detachment.

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