117results about How to "Eliminate measurement errors" patented technology

The invention relates to the technical field of data processing, in particular to a real estate surveying and mapping data processing method and system based on intelligent data. The method comprises the following steps: acquiring multi-source real estate surveying and mapping data; performing space-time synchronization on the multi-source real estate surveying and mapping data to generate multi-source real estate surveying and mapping space alignment data; real estate space feature extraction is carried out on the multi-source real estate surveying and mapping space alignment data to obtain real estate space feature data; performing cross-domain feature fusion on the multi-source real estate surveying and mapping data based on the real estate spatial feature data to generate real estate surveying and mapping fusion spatial feature data; public surveying and mapping point confirmation is carried out on the multi-source real estate surveying and mapping data through the real estate surveying and mapping fusion spatial feature data, and real estate surveying and mapping public surveying and mapping point data are obtained. Through multi-source data space-time synchronization, feature fusion, distortion correction, high-dimensional space reconstruction, semantic tag association and chain storage, the efficiency and accuracy of real estate surveying and mapping data processing are improved.

The invention provides a molten pool level online monitoring system and method, and the system comprises a data collection module, a data preprocessing module, a model training and optimizing module, an angle detection and compensation module, a nonlinear data processing module, a system testing and optimizing module, a display module, a communication module, and a control module. The online real-time monitoring of the molten pool level can be realized, the production automation level is improved, when the data acquisition module reaches a detection position, the control system triggers a signal through the coil, the camera is started to capture the images of the liquid level of the slag surface and the liquid level of the copper solution surface of the current molten pool, the online real-time monitoring function of the molten pool level is realized, and the production efficiency is improved. Compared with a traditional manual measurement or intermittent monitoring method, the method has the advantages that the detection efficiency can be greatly improved, the dependence on manual operation is reduced, and the automation level of the production process is improved.

The invention discloses an industrial equipment operation monitoring and early warning system based on an infrared temperature distribution technology, and the system comprises a temperature distribution image correction module which calculates a compensation coefficient of heat reflection on the surface of industrial equipment, and obtains a temperature distribution image after the reflection effect is corrected; the image displacement correction module is used for correcting temperature distribution image offset caused by displacement of the displacement component of the industrial equipment; the temperature abnormal area identification module is used for identifying a temperature abnormal area; the temperature anomaly region maintenance strategy making module is used for making a maintenance strategy of the temperature anomaly region; the temperature imbalance area identification module is used for identifying a temperature imbalance area in the non-temperature abnormal area; the temperature imbalance area maintenance module is used for formulating a preventive maintenance strategy of a temperature imbalance area; and the maintenance strategy execution and optimization module is used for continuously optimizing the maintenance strategy according to the maintenance task execution result. According to the method, the efficiency and effect of industrial equipment maintenance work are improved by combining an infrared thermal imaging technology and a multi-data correction and analysis method.

The invention provides an elevation data measurement method, device and equipment for a large-fall area, and relates to the technical field of engineering survey and geological survey. The method comprises the following steps: acquiring level gauge height difference data and measurement gravity data of each measurement point in a large-fall measurement area; carrying out regional division on the large-fall measurement region to obtain measurement sub-regions, and determining a gravity interference coefficient corresponding to a measurement point according to measurement gravity data and regional environment data of the measurement sub-regions; determining corrected gravity data based on the gravity interference coefficient and the measured gravity data, and determining an elevation correction item and measured elevation data; and correcting the measured elevation data according to the elevation correction item to obtain corrected elevation data corresponding to the large-fall measurement area. According to the technical scheme, the reliability and precision of elevation data measured by the level gauge in a large-fall area can be effectively improved.

The invention relates to a wind power blade mold closing seam thickness detection device and method. The device comprises a pressed body, a detection assembly, a power supply and a signal processor. The pressed body comprises a contact plate I and a contact plate II; one ends of the contact plate I and the contact plate II are connected through a revolute pair, the relative rotation axis of the contact plate I and the contact plate II is A, and the included angle between the two is an acute angle; the point, farthest from the axis A, on the contact plate I is B; the detection assembly is arranged on the upper surface of the contact plate II and connected with the negative electrode of the power supply through the signal processor. The contact plate I is connected with a power supply anode. After the web plate is closed, the contact plate I rotates relative to the contact plate II under the extrusion effect and makes contact with the upper end face of the detection assembly in sequence, and the distance between mold closing seams at the moment can be obtained according to the voltage input condition of the signal processor. According to the invention, the automatic detection and recording of the mold closing seam gap can be realized, the operation is simple and flexible, the detection precision is high, and the problems of measurement errors and the like caused by plasticine placement and manual measurement can be effectively solved.

The invention discloses a self-adaptive conductivity measurement method and system. The method comprises the following steps: 1) acquiring environment temperature and illumination intensity data in a set period in real time; 2) measuring the conductivity of the solution; 3) simulating physical and chemical processes in the solution by adopting a partial differential equation; and 4) calculating a conductivity compensation coefficient in combination with the differential equation model obtained in the step 3), and adjusting a conductivity measurement value in real time according to the conductivity compensation coefficient. According to the method, temperature and illumination change compensation is achieved through the partial differential equation model, measurement errors caused by environment change can be effectively eliminated, and therefore the accuracy and reliability of conductivity measurement in experiment and industrial application are improved.

The invention relates to the technical field of semiconductor detection, and discloses an ATE equipment high-speed AC signal calibration system and method, and the system comprises at least one FPGA module which is provided with a plurality of channels for bidirectional signal transmission; each PE module is correspondingly positioned on one channel of the FPGA and is used for receiving the driving signal output by the FPGA and an external input signal and sending a feedback signal to the FPGA module according to the driving signal; the signal calibration module is located in the FPGA and used for receiving the feedback signals and comparing time delays between the feedback signals input from different channels; the delay compensation module is positioned in the FPGA and is configured to adjust the time delay of each channel based on the comparison result of the signal calibration module so as to realize the synchronization of the signals of the plurality of channels; and when a plurality of FPGAs exist, the system also comprises a PLL module, and the PLL module is configured to provide synchronous clock signals with the same frequency and fixed phase to the plurality of FPGAs at the same time, so as to ensure that the internal clocks of the FPGAs are synchronous.

An automobile hub intelligent detection device disclosed by the present invention comprises a base station used for supporting a hub and a U-shaped installation frame arranged on the base station and used for fixing a plurality of groups of infrared distance measurement sensors, the infrared distance measurement sensors are electrically connected with a terminal module, and the base station is provided with a ring shaft structure for driving the infrared distance measurement sensors to detect the depth of the hub. The annular shaft structure comprises a center shaft which rotates on the base table in a fixed-axis mode, a plurality of sets of arc-shaped abutting bases which are arranged in an annular array mode and used for abutting against the inner circumferential face of the hub are arranged on the shaft injection base, and a sizing assembly which drives the arc-shaped abutting bases to synchronously move in the same direction or in the opposite directions is arranged on the base table. The wheel hub depth detection device is provided with a plurality of groups of infrared distance measuring sensors, comprehensive depth detection can be carried out on the wheel hub from different positions, the multi-azimuth measurement mode ensures that the depths of different positions of the same wheel base of the wheel hub are accurately evaluated, and the detection comprehensiveness and reliability are remarkably improved.

The invention belongs to the technical field of high-temperature thin film sensors, provides a high-temperature dynamic strain measurement method based on a thin film strain gauge, and is used for solving the problems that a traditional contact strain gauge is difficult to assemble, the surface structure of a part is damaged, and the accuracy is poor. The method comprises the following steps: firstly, arranging a film strain gauge and a temperature sensor on the surface of a test piece, and synchronously acquiring time-domain resistance signals and temperature information in the vibration process of the test piece; then, converting the time-domain resistance signal into a frequency-domain resistance signal by adopting spectral analysis, taking the resistance amplitude at the zero frequency as the initial resistance of the thin film strain gauge, and taking the resistance amplitude at the resonant frequency of the test piece as the resistance response quantity of the thin film strain gauge; and finally, determining a strain factor of the film strain gauge according to the temperature information, and calculating the dynamic strain of the test piece based on the initial resistance, the resistance response amount and the strain factor of the film strain gauge. On the basis, the strain measurement error is remarkably reduced, and the accuracy of dynamic strain measurement is improved.

The invention relates to a road collapse monitoring method and system by multiplexing an existing communication optical cable, the method comprises the steps of data acquisition and processing, conversion relation acquisition, mapping relation construction and road collapse monitoring, the system comprises a communication optical cable, a junction box, a distributed optical fiber demodulation device and a computing terminal, the computing terminal is used for implementing the method. Compared with the prior art, the method has the advantages of wide monitoring range, low monitoring cost, high real-time performance, high accuracy and the like.

The invention discloses a synthetic leather on-line thickness measuring method, which comprises the following steps: S1, taking a rolling shaft attached to the back surface of synthetic leather as a reference, carrying out data acquisition through a sensor, and carrying out data preprocessing; s2, calculating a roller error compensation value by adopting an error compensation algorithm, and correcting measurement data in real time; s3, filtering the vibration data to obtain the thickness after vibration compensation; s4, based on the speed and tension compensation model, obtaining the thickness after speed and tension compensation; s5, performing data fitting on the sampled data of each point; s6, combining the corrected measurement data, vibration compensation, speed and tension compensation and a data fitting result, and calculating a final thickness value of each point; according to the method, real-time high-precision measurement can be carried out on the thickness of the synthetic leather in a dynamic production environment by taking the surface of a roller as a reference surface and utilizing a multi-sensor redundancy design, an error compensation algorithm, data filtering and a speed and tension compensation model.

The invention belongs to the technical field of magnetic variable measurement, and particularly relates to a nuclear magnetic resonance magnetic variable measurement debugging device which comprises a mounting part, an inner supporting mechanism, a supporting mechanism, a control mechanism, a flow guide mechanism and an air inducing mechanism. The mounting part comprises a bearing bracket and a mounting box fixedly mounted on the side wall of the bearing bracket; the inner supporting mechanism comprises a bearing disc and a clamping jaw, the bearing disc is rotationally arranged on the inner wall of the bearing support, and the clamping jaw is slidably mounted on the outer wall of the bearing disc; the supporting mechanism comprises an arc-shaped frame and supporting rollers rotationally installed at the two ends of the arc-shaped frame. The arc-shaped frame is fixedly installed on the upper end face of the installation box. The control mechanism is used for controlling the clamping jaw to move; the air inducing mechanism comprises a control cylinder, an exhaust hood and an air inlet hood, the control cylinder is fixedly installed on the inner wall of the bearing support, and inner cavities of the exhaust hood and the air inlet hood are connected through the control cylinder; through cooperation of the structure, detection signal distortion is prevented, the magnetic variable measurement precision is greatly improved, and the full-detection requirement of batch production is met.

The utility model discloses an automatic water inlet and outlet device of circulating water aquaculture system relates to aquaculture technical field, including siphon drain pipe, with curved pipe section, the inlet end of siphon drain pipe is connected to the aquaculture pond, and the export end extends to the sewage bin, water level indicating pipe has the vertical pipe section with the intercommunication of aquaculture pond, and the top of vertical pipe section is communicated with atmosphere, makes its inside water level and aquaculture pond real -time synchronization, air pipe, one end intercommunication curved pipe section's top, the other end inserts the top of vertical pipe section, is used for controlling the start -stop of siphon drainage, wherein, the depth of air pipe insertion vertical pipe section is adjustable, is used for controlling the flow of siphon drainage. The utility model discloses a siphon drain pipe with curved pipe section is set up, utilizes siphon physical effect to realize zero -energy -consumption's drainage start and maintain, through setting up the air pipe of intercommunication curved pipe section top and inserting vertical pipe section, completes pure physical formula drainage start -stop control, and the need of artificial intervention is eliminated.

The invention relates to the technical field of control, in particular to a motor controller control method, device and equipment and a motor controller, and the method is applied to the motor controller of which each phase comprises at least two power switch devices connected in parallel. Acquiring the real-time temperature of the shell of each power switch device corresponding to the phase; compensating the real-time temperature based on a pre-calibrated initial offset value to obtain a temperature compensation value of the power switch device on the phase; determining a highest temperature compensation value and a lowest temperature compensation value corresponding to the phase, and calculating a temperature difference absolute value between the highest temperature compensation value and the lowest temperature compensation value; and controlling the working mode of the motor controller based on the temperature difference absolute value and the highest temperature compensation value of all phases in the motor controller. Whether each power switch device is in the non-current-sharing state or not is judged through the real-time shell temperature, hardware cost does not need to be newly increased, and the internal structure of the motor controller is simplified.

This application discloses a precision capacitance sensing system, comprising a modulation signal source, a sensitive probe, a differential transformer bridge, a signal amplification link, an analog multiplier, and a low-pass filter circuit, all connected in sequence. It also includes a demodulation reference signal source, the output of which is connected to the second input of the analog multiplier. The demodulation reference signal source is used to generate a multi-frequency combination demodulation reference signal, which is composed of a fundamental frequency component and at least two harmonic components superimposed. This invention also discloses a precision capacitance sensing method. By employing a specially designed demodulation reference signal, this application ensures that the system output remains constant within a continuously varying range of the demodulation phase difference, thereby achieving complete insensitivity to phase difference fluctuations and effectively overcoming the performance bottleneck that has long constrained high-precision capacitance sensing.

The present invention proposes an optical signal measurement system based on differential comparison compensation of reference light and reference light, which is realized by the following technical scheme: the light source provides a homologous measurement light signal and a reference light signal, the measurement light signal is attenuated after passing through the measurement medium, and then the measurement voltage signal is obtained after passing through the photoelectric conversion circuit, signal amplification circuit, and filtering circuit; the reference light signal directly passes through the same photoelectric conversion circuit, signal amplification circuit, and filtering circuit to obtain a reference voltage signal; the measurement voltage signal and the reference voltage signal are obtained through a differential comparison circuit to obtain a voltage signal that can be collected by an AD converter, and the CPU reads the AD collected signal through the data bus to calculate the measurement light intensity. When the light source fluctuates, the homologous measurement light and reference light fluctuate at the same time, and the measurement error caused by the power supply fluctuation is eliminated by the differential comparison circuit. The present invention aims to provide an optical signal measurement method with high stability and not affected by light source fluctuations.

The invention relates to the technical field of soil testing, and discloses a lateral pressure adjustable expansive soil expansion rate measuring device, which comprises an experiment box, a sample cylinder and a measuring module, symmetrical through holes are formed in the side wall of the sample cylinder, a lateral pressure loading system is correspondingly arranged on the outer side of each through hole, and each lateral pressure loading system comprises a rigid piston head capable of extending into the cylinder, a piston rod, a closed medium pressure cavity and a miniature constant pressure pump; the pump is connected with the pressure cavity through a pipeline, and the piston head is driven to apply adjustable lateral pressure to the sample by accurately feeding and discharging a medium; the measurement module comprises a vertical deformation and lateral pressure measurement system and integrates free expansion and lateral confinement expansion measurement functions; the rigid piston and the water medium are adopted for constant-pressure loading, the structure is simplified, operation is convenient and fast, rapid response and high-stability control over lateral pressure are achieved, the membrane embedding effect is thoroughly eliminated, a multi-stage constraint continuous test can be completed through one-time sample loading, and the test efficiency and data consistency are remarkably improved.

This utility model discloses a rapid testing device for rock deformation parameters, comprising a protective shell, one end of which is connected to the drill pipe and the other end to the drill bit. A power supply module, a resistance strain gauge group, a deformation parameter testing module, and a wireless transmission module are installed inside the protective shell. The power supply module provides power to the resistance strain gauge group, the deformation parameter testing module, and the wireless transmission module. The internal power supply line connecting the power supply module and the resistance strain gauge group is connected to the deformation parameter testing module via a signal transmission line. The deformation parameter testing module is electrically connected to the wireless transmission module. This utility model, by deploying resistance strain gauges, the deformation parameter testing module, and the wireless transmission module, monitors the strain signal generated by the interaction between the drilling equipment and the rock in real time, achieving rapid, accurate, and real-time testing of the Poisson's ratio of the rock mass during drilling, thereby guiding the evaluation of surrounding rock stability and the optimization design of support schemes in underground engineering.

The utility model discloses an insulation resistance detection system, and belongs to the technical field of power electronics. The insulation resistance detection system is used for determining insulation resistance between an alternating current output line and a protected ground and comprises a control module, an injection source generation circuit and a detection module, the control module is connected with the injection source generation circuit and the detection module, and the injection source generation circuit is connected with the detection module; the control module is used for controlling the detection module to be connected between the AC output line and the protected ground. Controlling the injection source generation circuit to inject at least two groups of different direct-current voltages to the detection module at different moments; acquiring at least two groups of different sampling voltages corresponding to the direct-current voltages acquired by a sampling resistor in the detection module; constructing an equivalent circuit model of the insulation resistance detection system based on the electrical characteristics of each electronic component in the insulation resistance detection system; and calculating the insulation resistance based on the at least two groups of different DC voltages, the at least two groups of different sampling voltages and the equivalent circuit model.

The utility model discloses a dial indicator fixing clamp for motor detection, which comprises a flange plate, a motor shaft movably connected to the center of the flange plate, a circular screw fixedly connected to the upper end of the motor shaft, a first connecting rod fixedly connected to the upper end of the circular screw, and a rotating arm group movably connected to one end of the first connecting rod. The rotating arm group comprises two rotating arms, and the rotating ends of the two rotating arms are connected with each other; through the connection between the circular screw rod and the motor shaft, the cooperative use of the clamping ball and the universal groove, and the connection between the positioning clamping groove and the positioning clamping block, the overall connection has stronger stability and reliability, and is not influenced by factors such as vibration, temperature and an external magnetic field; it is ensured that the dial indicator is always firmly fixed to a designated position in the detection process, the risk of falling possibly occurring in a traditional magnetic attraction mode is effectively avoided, measurement errors caused by displacement of the dial indicator are eliminated, and the reliability of planeness data of the flange face is ensured.

The utility model relates to a QFN (Quad Flat No-lead) dispensing and covering product measuring jig, which comprises a bottom plate and a measuring plate, the bottom plate is provided with an accommodating cavity for placing a product, a positioning pin is arranged in the accommodating cavity, the measuring plate is provided with a plurality of unit grooves, the product is provided with a plurality of packaging bodies, and each packaging body is provided with a cover plate. The product is placed in the containing cavity, the measuring plate covers the product, the cover plate is located in the unit groove, the product and the measuring plate are fixed through the positioning pin, and the measuring plate is made of stainless steel. According to the measuring jig, the packaging body on the product is rapidly positioned and exposed through the unit grooves of the measuring plate, so that a microscope can conveniently, rapidly and accurately measure the cover plate on the packaging body and the dispensing condition, and the measuring requirement of the small-particle packaging body is met.

The utility model discloses a plastic pipe external diameter laser measuring device, which comprises a spacing-adjustable supporting wheel, a rotation driving mechanism and a double-laser measuring head assembly, the supporting wheel adopts a V-shaped rubber rim structure to prevent axial displacement and surface scratch of a pipe, a rotation disc triggers a laser head through a magnetic encoder to acquire data at an equal angle interval of 0.1 degree, and the rotation driving mechanism is connected with the double-laser measuring head assembly. High-density uniform sampling is realized by combining closed-loop control of a servo motor; the three-axis measuring platform is provided with an electric adjusting mechanism, the laser head is automatically adjusted to the optimal focusing distance according to the initial measuring value, and the data processor dynamically optimizes the sampling frequency and calculates the ellipticity deviation. The device has the advantages that the influence of rotating speed fluctuation is eliminated through an angle triggering mode, the V-shaped supporting structure is matched with a DN 20-300 mm pipe, high-precision nondestructive measurement is guaranteed through a rubber protection layer and an automatic focusing mechanism, and the device is suitable for rapid detection of a continuous production line.

The utility model discloses a crack sensing sensor based on optical fiber sensing, and belongs to the technical field of civil structure health monitoring. The problems that the testing precision of an existing crack measuring device is extremely prone to being interfered by the surrounding environment, and the measuring precision is low are solved. The optical fiber grating sensor comprises a mounting shell, a cantilever beam and an optical fiber grating, the mounting shell is of a cavity structure with a fixed connecting end and a stretching movable end, and the fixed connecting end and the stretching movable end can slide relatively; the cantilever beam is of a long-strip-shaped structure with elastic deformation and resilience capacity, the cantilever beam is horizontally arranged in a cavity of the installation shell, the length direction of the cantilever beam is the same as the moving direction of the stretching movable end, the tip end of the cantilever beam is fixedly connected to the fixed connecting end, and the tail end of the cantilever beam abuts against the stretching movable end and is in a bent state. The fiber bragg grating is installed on the cantilever beam, and the length direction of the fiber bragg grating is consistent with the length direction of the cantilever beam. The device is mainly used for measuring cracks in the road surface and the roadbed.

The utility model belongs to the technical field of clamp especially is a kind of fixture for five-axis machining, including rotary table, the top of rotary table is equipped with protractor, the top of protractor is equipped with chuck mechanism, the top of chuck mechanism is equipped with centering vice fixed jack, the inboard of chuck mechanism is equipped with vice fixed mechanism, the top of chuck mechanism is connected with two-way centering vice device through centering vice fixed jack, the device can accurately, quickly position workpiece in the central position of two-way centering vice device top, facilitate centering work in the machining process, without relying on external measuring means (such as edge finder) and artificial calculation, eliminate measurement error from source, while improving workpiece in five-axis machining under multidirectional cutting force, traditional centering vice only from the direction of one axis to workpiece clamping, another axis lacks the limiting of workpiece, easily lead to workpiece along the direction of not being clamped " microshift", cause the problem of machining size out-of-tolerance.

The invention discloses a uranium layer thickness uniformity measuring and calculating method, which relates to the technical field of nuclear physical detection, and comprises the following steps: measuring the whole uranium layer on the surface of an electrode, firstly measuring the alpha particle emissivity of the whole surface of the electrode and a measured unit through a semiconductor detector, and then calculating to obtain the thickness uniformity of the uranium layer on the surface of the electrode. In the whole testing process, the semiconductor detector does not make contact with the electrodes, the uranium layer cannot be damaged, the semiconductor detector is high in precision and accurate in measurement result, and the uranium layer thickness uniformity can be reflected by the calculation result of the uranium layer thickness uniformity deviation coefficient. The invention further provides a uranium layer thickness uniformity measuring device which is applied to the uranium layer thickness uniformity measuring and calculating method, the alpha particles released by the uranium layer can be measured under the non-contact condition, the emissivity of the alpha particles is directly obtained, and data are provided for the uranium layer thickness uniformity deviation coefficient.

The application discloses a kind of line spectrum confocal sensor detection method, system and medium, the detection method, comprising: based on the height data at each position in scanning line direction, the inclination angle of current scanning line and the corresponding scanning line of standard installation in horizontal plane is analyzed;The relative movement of scanning line is controlled, and the deflection angle of the relative movement direction of sensor is analyzed according to the height information of the calibration object detected by scanning line at any two time;Based on the deflection angle and the inclination angle, the real position coordinates corresponding to the height of the surface of the measured object detected in scanning line direction are corrected to obtain the real surface topography of the measured object.The application corrects position to obtain the real position coordinates corresponding to the height data detected, adjusts the point cloud data of the reconstructed surface topography of the measured object, and improves the accuracy of the surface topography detection of the measured object.

The invention relates to the technical field of coal mine underground dust prevention and control, and discloses a working face negative pressure ventilation dust falling method, system and device. The method comprises the following steps that an intelligent control center obtains the real-time traction speed and the real-time coordinate position of a coal mining machine through a dust source tracking and positioning sensing unit; establishing coordinate mapping logic according to the real-time coordinate position so as to calculate the number of the hydraulic support currently corresponding to the coal mining machine; judging the running direction of the coal mining machine according to the sign sign of the real-time traction speed, and generating a support number set in an activated state at the current moment by combining a preset advanced dust pre-suction support number and a preset lagging purification support number; and sending an instruction to the distributed negative pressure dust collection device array according to the support number set in the activated state, and controlling the gas circuit control units in the support number set in the activated state to be started, so that a negative pressure suction and capture area is formed around the roller of the coal mining machine. According to the invention, accurate capture of the mobile dust production source and on-demand adjustment of the air volume are realized.

This invention relates to the field of transducer technology, specifically to an integrated coupled piezoelectric ultrasonic transducer, comprising an aluminum alloy cylindrical shell; silver-impregnated electrodes on both the upper and lower surfaces of the sensing unit, which simultaneously excite longitudinal and transverse waves under high-voltage pulse excitation; a backing damping block for absorbing reverse sound waves and improving signal clarity; a stainless steel bottom cover fixed to the open end of the shell and tightly coupled to a piezoelectric ceramic sheet, serving as protection and sound wave transition; an integrated coupling layer consisting of a flexible solid coupling sheet pre-attached to the outside of the stainless steel bottom cover; and a magnetic fixing ring, a ring-shaped neodymium iron boron permanent magnet embedded in the shell, for providing attraction force to the ferromagnetic bolts to stabilize the coupling pressure. Its advantages include: extremely simplified structure, compact size and light weight, low cost, elimination of measurement errors, improved measurement repeatability, and greatly simplified on-site operation procedures.