A precision weighing sensing system and method based on magnetic sensing technology

Abstract

This invention provides a precision weighing sensing system and method based on magnetic sensing technology. The invention uses the spatial magnetic potential equilibrium point of two magnets with opposite poles as the zero-position reference. The displacement of the bearing platform is converted into a magnetic field signal acquired by the magnetic sensing detection module. Based on the differential signal, an incremental PID algorithm is used to adjust the excitation current to generate a reverse electromagnetic force that forces the system back to zero. Under steady-state conditions, the excitation current, magnetic field state variables, and load distribution information are combined for joint calculation and off-center load correction. This solves the technical problems of nonlinear error in elastic force, zero-point drift, and lack of magnetic field state sensing and off-center load calibration in existing technologies. It eliminates the influence of creep in elastic components, achieves a stable physical zero-position reference, and provides online sensing of the magnetic circuit state and automatic compensation for off-center load errors.

Description

Technical Field

[0001] This invention relates to the field of precision measurement technology, and in particular to a precision weighing sensing system and method based on magnetic sensing technology. Background Technology

[0002] With the development of industrial automation and precision manufacturing, high-precision weighing technology has become a core requirement in fields such as experimental analysis, process control, and high-end metrology. Its measurement accuracy and stability directly affect product quality control and production efficiency, requiring more reliable and environmentally adaptable technical solutions to meet the needs of complex application scenarios.

[0003] Existing precision weighing technologies mainly include: mechanical weighing, which measures weight based on the deformation of an elastic body. When the platform is subjected to a load, the elastic body undergoes a deformation proportional to the load, and the weight value is indirectly obtained by detecting the deformation; optical weighing technology, which uses optical sensors to detect the absolute displacement position of the platform, and the system uses closed-loop control to return the platform to zero position, and the weight is characterized by excitation current or displacement, with the zero position usually defined as a fixed spatial coordinate position, and the displacement is read through an optical reading head; and resistance strain gauge weighing technology, which attaches resistance strain gauges to the surface of an elastic body, and the load causes the elastic body to deform, resulting in a change in the resistance value of the strain gauges, and the weight is obtained by measuring the change in resistance using a Wheatstone bridge. However, existing technologies have the following drawbacks:

[0004] 1) Mechanical weighing technologies (such as strain gauges and spring structures) rely on the deformation of elastic bodies to achieve measurement. Traditional elastic weighing structures either depend on a large deformation space, which is not conducive to applications under space constraints, or they can achieve weighing with small displacements, but cannot meet high-precision requirements. 2) Optical and resistive sensors are easily affected by the environment, such as dust interference, weak overload resistance, and are prone to irreversible damage due to impact. 3) Existing technical solutions lack methods for dynamically monitoring environmental changes to compensate for them. At the same time, traditional weighing methods do not have a calibration mechanism designed for off-center loading (load position deviation), resulting in significant measurement errors due to leverage effects or stress concentration when the load is eccentric, and the system lacks robustness. Therefore, there is an urgent need for a precision weighing sensing system and method that can solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a precision weighing sensing system and method based on magnetic sensing technology, which solves the problem of achieving low-cost, high-precision weighing in harsh environments.

[0006] According to an embodiment of the present invention, a precision weighing sensing system based on magnetic sensing technology includes:

[0007] A weighing platform device includes a weighing tray, a support body, and a base; wherein the support body is placed on the base and supports the weighing tray, and when the item to be weighed is placed on the weighing tray, the support body deforms; a magnetic component is provided at the bottom of the weighing tray.

[0008] The magnetic balancing unit includes two reference magnets, which have the same magnetism and are arranged with their same magnetic poles facing each other to obtain a spatial magnetic potential balance point; the spatial magnetic potential balance point corresponds to the initial position of the weighing tray to establish the zero-point reference of the system.

[0009] A magnetic sensing detection module includes at least two magnetic sensing units at different heights; the magnetic sensing detection module is connected to a weighing tray via a connecting structure and is used to simultaneously acquire the magnetic field strength signal of the magnetic balance unit.

[0010] The electromagnetic reset unit includes an excitation coil and an electromagnetic control unit. The excitation coil is fixed on the base and is arranged opposite to the magnetic component. The electromagnetic control unit receives the magnetic field information transmitted by the magnetic sensing module, calculates the differential and magnetic field state signals, and generates a control current to drive the excitation coil to generate a reverse electromagnetic force that acts on the magnetic component and returns the weighing tray to its initial position.

[0011] The mass calculation unit stores a mass calculation model, which is used to lock the excitation current when the system reaches steady state, calculate the weight by combining the magnetic field state signal, and calibrate by using load distribution information to output the weight of the weighed item.

[0012] Furthermore, the connection structure also includes a deformation amplification structure for amplifying the displacement of the magnetic sensing unit.

[0013] Furthermore, the deformation amplification structure includes an unequal-arm lever unit, with its short arm end connected to the weighing tray and its long arm end connected to the magnetic sensing detection module.

[0014] Furthermore, the magnetic sensing detection module includes multiple magnetic sensing units, the number of which is not less than 2n, where n is a natural number not less than 2; wherein, two magnetic sensing units with different height positions form a group to constitute a differential unit; the magnetic sensing detection module as a whole includes magnetic sensing units with at least two height values.

[0015] Furthermore, the magnetic sensing unit is any one of the following: Hall sensor, spin valve tunnel magnetoresistive (SOT) sensor, tunnel magnetoresistive (TMR) sensor, anisotropic magnetoresistive (AMR) sensor, fluxgate sensor, or giant magnetoresistance (GMI) sensor.

[0016] Furthermore, the electromagnetic reset unit employs an incremental PID control algorithm, using the differential signal as an error quantity to calculate the adjustment amount of the excitation current, specifically as follows:

[0017] ;

[0018] ;

[0019] in, This is the excitation current adjustment amount. This represents the error in the magnetic field differential information detected by the magnetic sensing module at the current sampling time. for The error amount corresponding to the magnetic field differential information detected by the magnetic sensing module at any given time. , , These are the proportional coefficient, integral coefficient, and differential coefficient, respectively. for The excitation current at any given moment.

[0020] Furthermore, the quality calculation model introduces a piecewise nonlinear correction function or a lookup table method to perform hysteresis compensation on the steady-state excitation current to correct the model's calculation results; the hysteresis compensation includes spatial mapping correction for assembly tolerances and magnetic circuit nonlinearity, and dynamic directional compensation for loading / unloading path differences.

[0021] Furthermore, it also includes a temperature detection unit, which is used to acquire the ambient temperature for feedback temperature drift compensation. Correspondingly, the quality calculation model introduces a piecewise nonlinear correction function or a lookup table method to perform temperature drift compensation on the steady-state excitation current, so as to compensate for real-time drift due to changes in ambient temperature.

[0022] Furthermore, the mass calculation unit identifies the load offset based on the symmetry of the differential information of multiple magnetic sensing units in the magnetic sensing detection module, and simultaneously corrects the mass calculation model for off-center load using a pre-stored off-center load correction matrix.

[0023] On the other hand, according to embodiments of the present invention, a precision weighing sensing method based on magnetic sensing technology is also provided, which includes the following steps:

[0024] S1: Arrange two reference magnets with the same pole facing each other to construct a magnetic balance system. By adjusting the position of the magnetic sensing module, obtain the spatial magnetic potential balance point and make it correspond to the initial position of the weighing tray to construct a zero-position reference.

[0025] S2: Load the material to be tested, the weighing tray moves down, and the support body deforms; the deformation drives the magnetic sensing detection module to shift through the connecting structure, generating a change in the magnetic field gradient;

[0026] S3: Collect the magnetic field signal transmitted by the magnetic sensing detection module, and calculate the differential signal and magnetic field state signal;

[0027] S4: The differential signal is used as the error quantity of the closed-loop control. The incremental PID control algorithm is used to update the excitation current, drive the excitation coil to generate a reverse electromagnetic force to act on the magnetic component, so that the weighing tray returns to the initial position and the system returns to the zero reference state.

[0028] S5: When the system reaches steady state, lock the stable excitation current, combine the magnetic field state signal to calculate the weight, and finally output the weight of the measured material.

[0029] S6: In step S5, the mass calculation unit further includes at least one of the following correction methods: temperature compensation, hysteresis compensation, and off-center load correction. The correction method is implemented by a piecewise nonlinear correction function or a lookup table method.

[0030] The technical principle of this invention is as follows: A spatial magnetic potential equilibrium point is constructed using the repulsion of like poles of a reference magnet as a zero-position reference; the deformation generated during weighing causes the magnetic sensing module to shift through a connecting structure, generating a change in the magnetic field gradient. The magnetic sensing module collects multiple magnetic field signals, calculates the differential signal and magnetic field state signal, and analyzes the spatial differences to obtain load distribution information; based on the differential signal, the excitation current is adjusted using an incremental PID algorithm to generate a reverse electromagnetic force that forces the system back to zero; under steady-state conditions, the excitation current is locked, and the material weight is output through a joint calculation model, combining the magnetic field state signal, ambient temperature, and load distribution information.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. By constructing a spatial magnetic potential equilibrium point using two reference magnets with their poles opposite each other as the zero-point reference, this method replaces the fixed spatial coordinate reference of traditional optical or resistive sensors. This solves the problem of zero-point drift caused by environmental temperature fluctuations, material aging, and external electromagnetic interference in existing optical and resistive sensors. It produces a stable physical zero-point reference based on magnetic field symmetry, unaffected by ambient light and pollution, and possessing overload protection capabilities. In particular, when using elastic components with minimal deformation, it avoids damage to deformable devices caused by large deformations under frequent overload conditions. It eliminates the need to maintain the linearity of the elastic component according to Hooke's Law, thus eliminating creep and nonlinear effects. This allows electromagnetic force to be directly equivalent to gravity without considering interference from elastic force components, greatly improving the reliability and accuracy of the weighing system.

[0033] 2. By using a connecting device that includes a deformation amplification structure to linearly amplify the displacement and drive the magnetic sensing detection module to deflect, and generating a reverse electromagnetic force under closed-loop zero control, the sensitivity can be amplified and the accuracy of the weighing system can be further improved.

[0034] 3. A matrix-type magnetic sensing detection module is used to simultaneously acquire multiple magnetic field signals, calculate differential signals, magnetic field state signals and load distribution information, and establish a joint calculation model by a mass calculation unit to perform off-center load correction. This solves the technical problems of existing technologies lacking real-time magnetic field state sensing capabilities and off-center load calibration mechanisms, realizes online sensing and adaptive compensation of magnetic circuit state and automatic correction of off-center load errors, and improves the reliability of the system.

[0035] 4. The magnetic sensing detection module uses magnetic sensing units with at least two heights, which can effectively sense the displacement changes of the magnetic sensing detection module. In practical applications, four height values ​​can also be set to further improve the recognition accuracy by increasing the sensing density of the spatial magnetic field, providing rich parameter acquisition support for compensation and calibration. Attached Figure Description

[0036] Figure 1 This is a system block diagram according to an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram of the magnetic balance and differential detection principle in an embodiment of the present invention.

[0038] Figure 3 This is a flowchart illustrating the steps of another embodiment of the present invention.

[0039] In the above figures: 1. Weighing tray; 2. Support body; 3. Base; 4. Magnetic component; 5. Reference magnet; 6. Magnetic sensing detection module; 7. Magnetic sensing unit; 8. Excitation coil. Detailed Implementation

[0040] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0041] like Figure 1 As shown, this embodiment of the invention proposes a precision weighing sensing system based on magnetic sensing technology, comprising:

[0042] The weighing platform device includes a weighing tray 1, a support body 2 and a base 3; wherein the support body 2 is placed on the base 3 and supports the weighing tray 1, and the support body 2 deforms when the item to be weighed is placed on the weighing tray 1; a magnetic component 4 is provided at the bottom of the weighing tray 1.

[0043] The magnetic balance unit includes two reference magnets 5, which have the same magnetism and are arranged with the same magnetic poles facing each other to obtain a spatial magnetic potential balance point; the spatial magnetic potential balance point corresponds to the initial position of the weighing tray 1 to construct the zero point reference of the system.

[0044] The magnetic sensing detection module 6 includes at least two magnetic sensing units 7, which are positioned at different heights. The magnetic sensing detection module 6 is connected to the weighing tray 1 via a connecting structure and is used to simultaneously acquire the magnetic field strength signal of the magnetic balance unit.

[0045] The electromagnetic reset unit includes an excitation coil 8 and an electromagnetic control unit. The excitation coil 8 is fixed on the base 3 and positioned opposite the magnetic component 4. The electromagnetic control unit receives magnetic field information transmitted by the magnetic sensing module 6, calculates differential and magnetic field state signals, and generates a control current to drive the excitation coil 8 to generate a reverse electromagnetic force acting on the magnetic component 4, thus returning the weighing tray 1 to its initial position. In one embodiment, the electromagnetic control unit also includes a DAC conversion unit and a linear amplification drive unit. The control chip of the electromagnetic control unit generates a reference drive voltage through the DAC conversion unit and the linear amplification drive unit, which can generate a corresponding excitation current for a coil with a specific reactance. In another embodiment, a closed-loop controllable constant current source can be used to adjust the excitation current in real time, helping to maintain the weighing tray 1 in its initial position during the weighing process.

[0046] The mass calculation unit stores a mass calculation model, which is used to lock the excitation current when the system reaches steady state, calculate the weight by combining the magnetic field state signal, and calibrate by using load distribution information to output the weight of the weighed item.

[0047] Its detailed working description is as follows:

[0048] Considering that optical sensors rely on a light-transmitting environment and are easily blocked by oil and dust, leading to failure, the magnetic balance unit of this invention utilizes the spatial penetration characteristics of magnetic fields to construct a non-contact magnetic potential reference through a reference magnet 5, thereby achieving stable zero-point calibration even in enclosed or harsh environments.

[0049] The magnetic balancing unit comprises two reference magnets 5, arranged with their poles opposite each other (i.e., N pole to N pole or S pole to S pole). Based on the principle of magnetic repulsion between like poles, a stable magnetic potential equilibrium point is formed at the center between the two reference magnets 5. In the initial installation state, the relative positions of the magnetic sensing module 6 or the two reference magnets 5 are adjusted so that the magnetic potential equilibrium point corresponds to the initial state of the weighing tray 1 when no material is loaded. When the system is in equilibrium, the magnetic field gradient at this point is theoretically zero or in a symmetrical equilibrium state. After the initial position adjustment is completed, the positions of the reference magnets 5 remain fixed.

[0050] In some examples, neodymium iron boron (NdFeB) with high remanence and high coercivity can be used as the permanent magnet material to ensure magnetic field stability. Two reference magnets 5 are fixed at specific positions on the weighing mechanism, with their magnetization directions opposite each other. The distance between the two magnets is finely adjusted using a precision displacement stage, and the magnetic field at the center point is detected using a gaussmeter until the position with the minimum magnetic field vector sum (or gradient symmetry) is found, which is then locked as the zero-position reference of the system.

[0051] By constructing a spatial magnetic potential equilibrium point, the "optical axis alignment" reference in traditional optical solutions is replaced, eliminating the dependence on precision optical lenses and a clean, transparent environment, and solving the problem of existing technologies being easily contaminated and failing.

[0052] As one embodiment, the deformation of the support 2 during the weighing process can be very small to adapt to high-load environments and reduce creep of elastic components or failure of elastic materials. Considering that the displacement of the bearing platform is very small during the weighing process, the resulting change in the magnetic field is weak, leading to insufficient magnetic sensing signal-to-noise ratio, this invention uses a connecting structure to linearly amplify the deformation displacement, so that the magnetic sensing area obtains an amplified equivalent displacement signal, thereby improving the system sensitivity.

[0053] The connection structure includes a deformation amplification structure for amplifying the displacement of the magnetic sensing unit 7. In this preferred embodiment, the deformation amplification structure adopts a scissor-type linkage structure, which includes an unequal-arm lever unit. The short arm end is connected to the weighing tray 1, and the long arm end is correspondingly set with the reference magnet 5 or the magnetic field detection area. The mechanical amplification factor is determined by the length ratio of the linkage. When the material to be measured is loaded onto the weighing tray 1, its gravity causes the weighing tray 1 to produce a small vertical displacement, which is linearly amplified by the deformation amplification structure.

[0054] The amplified displacement drives the magnetic sensing module 6 to synchronously shift its spatial position, resulting in a change in the magnetic field gradient or magnetic flux density. Based on the functional relationship between the magnetic field and distance, within the linear range of a small displacement, this change can be approximated as:

[0055] ;

[0056] in, This is the magnified equivalent displacement; The magnetic field gradient coefficient is determined by the geometric dimensions, material remanence, and relative distance between the two reference magnets 5.

[0057] While maintaining the accuracy of closed-loop zeroing control, this invention amplifies the displacement signal, enabling the magnetic sensing module 6 to more sensitively capture changes in the magnetic field and improve system resolution. At the same time, the mechanical amplification factor can be precisely set through the link length ratio, making it easy to adapt to different range requirements.

[0058] Compared to a single magnetic sensor that can only acquire local magnetic field strength and cannot distinguish spatial distribution differences caused by off-center loading, magnetic circuit inhomogeneity, or temperature gradient, resulting in measurement errors that cannot be identified and compensated, this invention uses a matrix magnetic sensing detection module 6, which simultaneously acquires multiple magnetic field signals through multiple magnetic sensing units 7, realizing integrated detection of magnetic field information.

[0059] The matrix magnetic sensing detection module 6 of the present invention is set in the magnetic field action area of ​​the magnetic balance unit, preferably in a 6-point array or a 9-point array arrangement and connected to the weighing tray 1 through a connecting structure, for simultaneously acquiring the magnetic field strength signal of the magnetic balance unit.

[0060] The magnetic sensing module 6 includes multiple magnetic sensing units 7 (the number of magnetic sensing units 7 is not less than 2n, where n is a natural number not less than 2), wherein two magnetic sensing units 7 with different height positions form a group to constitute a differential unit; the magnetic sensing module 6 as a whole contains magnetic sensing units 7 with at least two height values.

[0061] The optional magnetic sensing unit types include, but are not limited to, Hall effect sensors, TMR (tunneling magnetoresistive), AMR (anisotropic magnetoresistive), GMI (giant magnetoresistance), or fluxgate sensors. Its principle is to use differential operations to eliminate environmental common-mode noise, retaining only the differential-mode signal caused by the weighing platform offset; simultaneously, load distribution information is obtained through spatial difference analysis of multi-channel signals. The specific implementation process is as follows... Figure 2 As shown:

[0062] When the system is at zero position, the magnetic field strength detected by each magnetic sensing unit is theoretically equal, and the differential output... =a, where a is an initial constant, which can also be set to 0. When the support platform moves the magnetic sensing module 6, the magnetic field detected by the magnetic sensing unit 7 on one side increases ( The other side weakens ( ).

[0063] The signals from each magnetic sensing unit 7 are acquired in real time, and the following calculations are performed:

[0064] (1) Differential signal: Select the output voltages of the two magnetic sensing units 7 in the differential unit, perform subtraction operation to obtain the differential voltage signal. :

[0065] ;

[0066] The corresponding magnetic field relationship is as follows .in, This represents the sensitivity coefficient of the magnetic sensor. Combining this with the aforementioned formula, the proportional relationship between the voltage signal and the corresponding magnetic field for a small displacement can be obtained. The correspondence between the differential voltage signal and the displacement can be obtained through calibration.

[0067] (2) Magnetic field state signal: The arithmetic mean of the outputs of all magnetic sensing units 7 is taken to obtain the corresponding electrical signal of the magnetic field state:

[0068] ;

[0069] in, This is a magnetic field state signal. This represents the number of magnetic sensing units 7. This represents the output voltage of each magnetic sensing unit. This magnetic field state signal is used to characterize the current magnetic circuit state and can reflect the effects of factors such as changes in the remanence of the reference magnet 5, magnetic circuit aging, assembly deviations, and temperature changes.

[0070] (3) Load distribution information: Based on the spatial distribution differences of the magnetic sensing unit 7 at different positions, calculate the offset of the load center relative to the geometric center of the weighing tray 1.

[0071] This invention uses a matrix-type multi-sensor to acquire multiple magnetic field signals, enabling differential common-mode detection, off-center load correction, and online sensing of magnetic circuit status, thereby improving reliability.

[0072] To address the issues of elastic decay and creep in traditional mechanical springs, and the measurement errors caused by changes in the elastic coefficient after long-term use, the electromagnetic reset unit of this invention uses an excitation coil 8 to generate a reverse electromagnetic force to force the system back to the magnetic balance zero position. It replaces the mechanical spring with the definite relationship between electromagnetic force and current to achieve contactless force balance.

[0073] The specific working process of the electromagnetic reset unit is as follows:

[0074] Real-time reading of differential voltage signals Construct closed-loop control error .

[0075] Considering the system's dynamic response and anti-interference requirements, this invention employs an incremental PID control algorithm to achieve fast, stable control with zero steady-state error. This algorithm is based on the error at the current moment. Error at the previous time step and the error between the first two time points Calculate the adjustment amount of the excitation current:

[0076] ;

[0077] in, This is the excitation current adjustment amount. , , These are the proportional coefficient, integral coefficient, and differential coefficient, respectively.

[0078] Update the current excitation current:

[0079] ;

[0080] in, for The excitation current at any given time generates a PWM wave or analog current signal to drive the toroidal excitation coil 8. The magnetic field line loop, consisting of the coil, magnetic component 4, air gap, and armature, has most of its magnetic flux confined in a low-resistivity magnetic material, with a magnetic voltage drop only at the working air gap, satisfying the engineering approximation conditions for a near-closed magnetic circuit.

[0081] Under near-closed magnetic circuit conditions, the reverse electromagnetic force The size follows the formula:

[0082] ;

[0083] in, It is a reverse electromagnetic force. The number of coil turns. For excitation current, The permeability of free space, For effective magnetic pole area, This refers to the air gap distance. If structural limitations in actual engineering result in significant magnetic leakage, a magnetic leakage coefficient can be introduced into the control algorithm. The formula has been modified, and the modified formula is as follows:

[0084] ;

[0085] in, Obtained through finite element simulation or actual measurement calibration.

[0086] It should be noted that this electromagnetic force The goal of generating it is not to directly and completely counteract all gravity. Instead, it counteracts the magnetic balance disturbance caused by the gravity of the measured material, forcing the system to return to the zero reference.

[0087] When the system returns to the zero reference, the differential signal approaches the initial constant or the set zero value. Under steady-state conditions, the elastic force provided by the elastic element... Therefore, the electromagnetic force is approximately equal to the weight of the material being measured.

[0088] ;

[0089] At this point, the excitation current tends to stabilize. The closed-loop control unit locks the steady-state excitation current. It is then output to the mass calculation unit for subsequent weight calculation.

[0090] This unit implements zero-position weighing, and the system always operates near the magnetic equilibrium point, eliminating nonlinear errors caused by mechanical deformation; the electromagnetic force and current have a square relationship, resulting in high control accuracy; there is no mechanical friction, ensuring good long-term stability; the mass calculation can be directly based on the equivalent relationship between electromagnetic force and gravity, simplifying the mathematical model.

[0091] In this embodiment, the mass calculation unit embeds a current locking module and a mass calculation model, responsible for locking the steady-state equilibrium current and calculating it into the final weight value. The current locking module judges fluctuations by continuously sampling the excitation current for multiple cycles and filters out instantaneous interference signals; only when the differential signal and the excitation current are synchronously stable will the module latch the current effective excitation current for subsequent calculation.

[0092] Considering that the residual magnetism of the reference magnet 5 changes with time and temperature, magnetic circuit aging and assembly tolerances will cause the current-mass mapping relationship to drift, and that off-center loading will cause additional measurement errors, this invention adopts a joint calculation model that includes steady-state excitation current, magnetic field state signal and ambient temperature parameters, and introduces an off-center loading correction mechanism to achieve adaptive compensation through multi-parameter fusion.

[0093] In a magnetic balance system, there is a mapping relationship between the steady-state excitation current and the weight, but this relationship is affected by the magnetic circuit state. Therefore, joint calculation can eliminate errors caused by changes in the magnetic circuit. Simultaneously, the load distribution information is used to correct the weight value through a pre-stored off-center load correction matrix. The specific working steps are as follows:

[0094] Continuously monitor the differential signal, when When the excitation current approaches its initial constant and the change in excitation current over multiple consecutive sampling periods is less than a preset threshold, the system is considered to have reached steady state. At this point, the current excitation current value is locked and recorded as the steady-state excitation current. .

[0095] The mass calculation unit reads the magnetic field strength signals output by all current magnetic sensing units 7 from the matrix magnetic sensing detection module 6 and calculates the magnetic field state signal; simultaneously, it reads the current ambient temperature from the temperature sensing element. Based on the spatial distribution differences of the magnetic field strength signals output by each magnetic sensing unit 7, it calculates the offset of the load center relative to the geometric center of the weighing tray 1. This yields load distribution information.

[0096] The pre-stored basic mass calculation model is invoked. This model is a joint function containing steady-state excitation current, magnetic field state signal, and ambient temperature, and its basic form is:

[0097] In this preferred embodiment, the function can be expressed in polynomial form:

[0098] ;

[0099] in , , , These are the system parameters obtained through calibration using standard weights. To improve fitting accuracy, cross terms can be introduced to overcome problems such as parameter coupling or opposing effects between parameters. .

[0100] In this preferred embodiment, based on the load center offset Call the pre-stored off-center load correction matrix For the initial weight value Make corrections:

[0101] ;

[0102] Where the off-load correction matrix The calibration is obtained by multi-point calibration of standard weights at different loading positions. The specific calibration method is as follows: place standard weights of known weight at different positions (center, left, right, front, back, etc.) on the weighing pan 1, record the measurement deviation at each position, and obtain the correction matrix elements by least squares fitting.

[0103] In this preferred embodiment, to correct for hysteresis effects, assembly tolerances, and nonlinear errors under high precision conditions, the present invention employs a multi-dimensional system calibration strategy, introducing a piecewise nonlinear correction function or a lookup table method to compensate for hysteresis and temperature drift of the steady-state excitation current, thereby correcting the model's solution results. The specific implementation logic of this strategy is as follows:

[0104] 1) Spatial mapping correction for magnetic circuit nonlinearity and assembly tolerance:

[0105] Due to batch variations in the performance (remanence Br) of reference magnet 5, and the coaxiality and air gap distance of the dual magnets during assembly... Inevitably, tolerances exist, leading to variations in the magnetic field gradient coefficient. Deviation from theoretical values. In the factory calibration stage, this invention employs a unit-by-unit, point-by-point calibration method: using a high-precision standard weight sequence (covering the entire range) to perform load tests on each device. By collecting actual displacement-magnetic field response curves, a unique "displacement-current" polynomial model for the device is constructed. This piecewise correction function is essentially a deviation mapping table between the theoretical linear model and the actual physical response; its correction target directly corresponds to the systematic baseline error introduced by the mechanical assembly and differences in magnet performance of the current device.

[0106] 2) Dynamic directional compensation for hysteresis effect

[0107] To address the hysteresis error caused by magnetic hysteresis, this invention records the steady-state current values ​​of the loading up curve and the unloading down curve separately during the calibration process, constructing a dual-path lookup table. During actual measurement, the system identifies whether the current process is a "loading process" or a "unloading process" by judging the changing trend (positive or negative slope) of the error signal e(t), and then calls the corresponding up or down correction table for interpolation compensation. This mechanism directly correlates the correction function with the dynamic direction of the current load change, thereby accurately eliminating the repeatability error caused by magnetic hysteresis.

[0108] 3) Environmental-related compensation for temperature drift

[0109] In some examples, the present invention integrates a temperature sensor near the magnetic sensing module. During wide-temperature-range calibration (e.g., -10°C to 50°C), the zero-point offset and sensitivity changes at different temperature nodes are recorded to generate a three-dimensional calibration table (temperature-load-current). In actual operation, the system reads the ambient temperature in real time and adjusts the coefficients in the weight calculation model in real time through multidimensional linear interpolation. and This lookup table method closely corresponds the correction function to the actual thermodynamic environment, effectively eliminating measurement drift caused by the attenuation of magnetic properties of the reference magnet 5 due to temperature changes.

[0110] The basic form of its piecewise nonlinear correction function is:

[0111] ;

[0112] in, , , , The calibration parameters were obtained using standard weights.

[0113] The weight value after off-center load correction and compensation is output as the final measurement result.

[0114] This invention enables online sensing and adaptive compensation of the magnetic circuit state. When the performance of the reference magnet 5 deteriorates or the ambient temperature changes, the model automatically adjusts the current-mass mapping relationship without manual calibration. Off-center load correction further eliminates measurement errors caused by load position offset. This comprehensively improves the system's long-term stability, environmental adaptability, and measurement accuracy.

[0115] On the other hand, embodiments of the present invention also provide a precision weighing sensing method based on magnetic sensing technology, which is implemented based on the system described above, such as... Figure 3 As shown, it includes the following steps:

[0116] S1: Arrange two reference magnets 5 with their same poles facing each other to construct a magnetic balance system. By adjusting the position of the magnetic sensing module 6, obtain the spatial magnetic potential balance point and make it correspond to the initial position of the weighing tray 1 to construct a zero-position reference.

[0117] S2: When the material to be tested is loaded, the weighing tray 1 moves down, and the support 2 deforms; the deformation drives the magnetic sensing detection module 6 to shift through the connecting structure, generating a change in the magnetic field gradient;

[0118] S3: Collect the magnetic field signal transmitted by the magnetic sensing module 6, and calculate the differential signal and magnetic field state signal;

[0119] S4: The differential signal is used as the error quantity of the closed-loop control. The incremental PID control algorithm is used to update the excitation current, drive the excitation coil 8 to generate a reverse electromagnetic force to act on the magnetic component 4, so that the weighing tray 1 returns to the initial position and the system returns to the zero reference state.

[0120] S5: When the system reaches steady state, lock the stable excitation current, combine the magnetic field state signal to calculate the weight, and finally output the weight of the measured material.

[0121] S6: In step S5, the mass calculation unit also includes at least one of the following correction methods: temperature compensation, hysteresis compensation, and off-center load correction. The correction method is implemented by a piecewise nonlinear correction function or a lookup table method.

[0122] The above methods enable the system to adapt to harsh environments and maintain a high degree of accuracy in weighing, resulting in better reliability compared to existing technologies.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A precision weighing sensing system based on magnetic sensing technology, characterized in that: include: The weighing platform device includes a weighing tray (1), a support body (2) and a base (3); wherein the support body (2) is placed on the base (3) and supports the weighing tray (1); when the item to be weighed is placed on the weighing tray (1), the support body (2) deforms; a magnetic component (4) is provided at the bottom of the weighing tray (1). The magnetic balance unit includes two reference magnets (5), which have the same magnetism and are arranged with the same magnetic poles facing each other to obtain a spatial magnetic potential balance point. The spatial magnetic potential equilibrium point corresponds to the initial position of the weighing tray (1) to construct the zero-point reference of the system; The magnetic sensing detection module (6) includes at least two magnetic sensing units (7), which are at different heights. The magnetic sensing detection module (6) is connected to the weighing tray (1) through a connection structure and is used to simultaneously collect the magnetic field strength signal of the magnetic balance unit. The electromagnetic reset unit includes an excitation coil (8) and an electromagnetic control unit. The excitation coil (8) is fixed on the base (3) and is arranged opposite to the magnetic component (4). The electromagnetic control unit receives the magnetic field information transmitted by the magnetic sensing detection module (6), calculates the differential and magnetic field state signals, and generates a control current to drive the excitation coil (8) to generate a reverse electromagnetic force to act on the magnetic component (4) and make the weighing tray (1) return to the initial position. The mass calculation unit stores a mass calculation model, which is used to lock the excitation current when the system reaches steady state, calculate the weight by combining the magnetic field state signal, and calibrate by using load distribution information to output the weight of the weighed item.

2. The precision weighing sensing system based on magnetic sensing technology as described in claim 1, characterized in that: The connection structure also includes a deformation amplification structure for amplifying the displacement of the magnetic sensing unit (7).

3. A precision weighing sensing system based on magnetic sensing technology as described in claim 2, characterized in that: The deformation amplification structure includes an unequal-arm lever unit, the short arm of which is connected to the weighing tray (1), and the long arm of which is connected to the magnetic sensing detection module (6).

4. The precision weighing sensing system based on magnetic sensing technology as described in claim 1, characterized in that: The magnetic sensing detection module (6) includes multiple magnetic sensing units (7), and the number of magnetic sensing units (7) is not less than 2n, where n is a natural number not less than 2; wherein, two magnetic sensing units (7) with different height positions form a group to constitute a differential unit; the magnetic sensing detection module (6) as a whole includes at least two magnetic sensing units (7) with different height values.

5. A precision weighing sensing system based on magnetic sensing technology as described in claim 1, characterized in that: The magnetic sensing unit (7) is any one of the following: Hall sensor, spin valve tunnel magnetoresistive (SOT) sensor, tunnel magnetoresistive (TMR) sensor, anisotropic magnetoresistive (AMR) sensor, fluxgate sensor, or giant magnetoresistance (GMI) sensor.

6. A precision weighing sensing system based on magnetic sensing technology as described in claim 1, characterized in that: The electromagnetic reset unit employs an incremental PID control algorithm, using the differential signal as the error quantity to calculate the adjustment amount of the excitation current, specifically: ； ； in, This is the excitation current adjustment amount. This represents the error amount of the magnetic field differential information detected by the magnetic sensing module (6) at the current sampling time. for The error amount of the magnetic field differential information detected by the magnetic sensing detection module (6) at any given time corresponds to the amount of error. , , These are the proportional coefficient, integral coefficient, and differential coefficient, respectively. for The excitation current at any given moment.

7. A precision weighing sensing system based on magnetic sensing technology as described in claim 1, characterized in that: The quality calculation model introduces a piecewise nonlinear correction function or a lookup table method to perform hysteresis compensation on the steady-state excitation current in order to correct the model's calculation results; the hysteresis compensation includes spatial mapping correction for assembly tolerances and magnetic circuit nonlinearity, and dynamic directional compensation for loading / unloading path differences.

8. A precision weighing sensing system based on magnetic sensing technology as described in claim 7, characterized in that: It also includes a temperature detection unit, which is used to acquire the ambient temperature for temperature drift compensation. Correspondingly, the quality calculation model introduces a piecewise nonlinear correction function or a lookup table method to perform temperature drift compensation on the steady-state excitation current, so as to compensate for real-time drift due to changes in ambient temperature.

9. A precision weighing sensing system based on magnetic sensing technology as described in claim 4, characterized in that: The mass calculation unit identifies the load offset based on the differential information symmetry of multiple magnetic sensing units (7) in the magnetic sensing detection module (6), and simultaneously corrects the load offset of the mass calculation model using a pre-stored off-load correction matrix.

10. A precision weighing sensing method based on magnetic sensing technology, characterized in that: The method is implemented based on a precision weighing sensing system based on magnetic sensing technology as described in any one of claims 1-9, and includes the following steps: S1: Arrange two reference magnets (5) with their poles facing each other to construct a magnetic balance system. By adjusting the position of the magnetic sensing module (6), obtain the spatial magnetic potential balance point and make it correspond to the initial position of the weighing tray (1) to construct a zero-position reference. S2: Load the material to be tested, the weighing tray (1) moves down, and the support (2) deforms; the deformation drives the magnetic sensing detection module (6) to shift through the connecting structure, generating a change in the magnetic field gradient; S3: Collect the magnetic field signal transmitted by the magnetic sensing detection module (6) and calculate the differential signal and magnetic field state signal; S4: The differential signal is used as the error quantity of the closed-loop control. The incremental PID control algorithm is used to update the excitation current, drive the excitation coil (8) to generate a reverse electromagnetic force to act on the magnetic component (4), so that the weighing tray (1) returns to the initial position and the system returns to the zero reference state. S5: When the system reaches steady state, lock the stable excitation current, combine the magnetic field state signal to calculate the weight, and finally output the weight of the measured material. S6: In step S5, the mass calculation unit further includes at least one of the following correction methods: temperature compensation, hysteresis compensation, and off-center load correction. The correction method is implemented by a piecewise nonlinear correction function or a lookup table method.

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