Spatially distributed force measurement device and method based on flexible coil array

Abstract

The application discloses a kind of spatial distributed force measuring device and method based on flexible coil array: double-layer triangular spiral flexible coil measuring module includes magnetostrictive sensitive layer, excitation coil, top layer triangular spiral detection coil, bottom layer triangular spiral detection coil, flexible substrate;Excitation coil generates alternating magnetic field near magnetostrictive sensitive layer, top layer and bottom layer triangular spiral detection coil are orthogonally arranged, detect different direction force magnetic response signal, and output different direction detection voltage signal;Signal acquisition and processing module acquires the detection voltage signal output by each detection coil, and obtains the output voltage variation of each measuring module in two orthogonal detection directions after processing;Space force reconstruction module is according to the output voltage variation of each measuring module, spatial position information, pre-calibrated spatial response matrix, joint solution reconstruction, obtains the size, position and spatial distribution of external force.The application is suitable for distributed force measurement on plane, curved surface or flexible substrate.

Description

Technical Field

[0001] This invention relates to the field of force sensing and distributed force measurement technology, and more specifically, to a spatial distributed force measurement device and method based on a flexible coil array. This device is capable of simultaneously sensing, jointly calculating, and reconstructing the distribution of multiple external forces existing at multiple spatial locations within a measurement area. It can be applied to scenarios such as flexible structures, elastomer surfaces, robot tactile sensing, force monitoring of intelligent manufacturing equipment, and force distribution detection in complex spatial areas. Background Technology

[0002] Force is a crucial physical quantity in mechanical system state perception, structural health monitoring, and intelligent equipment control. In fields such as robotics, precision manufacturing, aerospace, medical devices, and human-computer interaction, in addition to obtaining the magnitude of single-point forces or resultant forces, it is often necessary to obtain the force distribution within a specific region or space. For example, when external loads act on flexible surfaces, elastic support structures, or complex spatial regions, the local force state at different locations is not the same, and relying solely on a single sensor is insufficient to comprehensively reflect the mechanical distribution characteristics within the force-bearing space.

[0003] Existing force sensing methods mainly include resistance strain gauge, capacitive, piezoelectric, fiber optic, and magnetoelastic methods. Among these, resistance strain gauge sensors have a mature structure but require sophisticated bonding processes and bridge compensation, and their wiring is complex for large-area distributed measurements. Capacitive sensors have high sensitivity but are easily affected by environmental humidity, gap variations, and parasitic capacitance. Piezoelectric sensors are suitable for dynamic force measurement but have limited capabilities for static force measurement. Fiber optic sensors have strong resistance to electromagnetic interference, but their demodulation systems are complex and costly. For spatially distributed force measurement, these methods often suffer from problems such as large sensor unit size, difficulty in array integration, insufficient spatial resolution, or complex decoupling calculations.

[0004] In recent years, flexible sensing technology based on the force-magnetic coupling effect has provided a new approach for distributed measurement. It utilizes the change in permeability of magnetostrictive materials under stress to convert mechanical signals into measurable electromagnetic parameters. However, existing coil structures are mostly circular or rectangular planar spirals, which have limited magnetic field concentration within a finite sensitive area, poor directional sensitivity, and difficulty in achieving multi-dimensional force vector decoupling. Especially when applied to spatial force field measurements, traditional coil layouts struggle to balance high spatial resolution with signal crosstalk suppression, resulting in limited accuracy in force distribution inversion.

[0005] Therefore, there is an urgent need for a new distributed force sensing scheme that combines high flexibility, high spatial resolution, good orientation sensitivity and easy arraying characteristics to address the shortcomings of existing technologies in continuous and accurate measurement of complex spatial force fields. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention proposes a spatial distributed force measurement device and method based on a flexible coil array. This method involves uniformly arranging n double-layer triangular spiral flexible coil measurement modules, each capable of detecting orthogonal mechanical responses, within the measurement area. By utilizing the spatial position and output signal of each triangular spiral flexible coil measurement module, a functional relationship between force and spatial position is established, thereby obtaining information on the magnitude and distribution of external forces within the measured space. Furthermore, this invention can be adapted to distributed force measurement on planar, curved, or flexible substrates by changing the number, spacing, and shape of the double-layer triangular spiral flexible coil measurement modules.

[0007] The objective of this invention can be achieved through the following technical solutions.

[0008] A spatially distributed force measurement device based on a flexible coil array includes several double-layer triangular spiral flexible coil measurement modules, an excitation module, a signal acquisition and processing module, and a spatial force reconstruction module. Each of the aforementioned double-layer triangular spiral flexible coil measurement modules includes, from top to bottom, a magnetostrictive sensitive layer, an excitation coil, a top triangular spiral detection coil, a bottom triangular spiral detection coil, and a flexible substrate. The excitation coil is used to generate an alternating magnetic field near the magnetostrictive sensitive layer. The top triangular spiral detection coil and the bottom triangular spiral detection coil are arranged in mutually orthogonal directions and are used to detect force-magnetic response signals in different directions, respectively, and output detection voltage signals in different directions. The excitation module is used to provide a sinusoidal excitation signal to the excitation coil of each double-layer triangular spiral flexible coil measurement module; The signal acquisition and processing module is used to acquire the detection voltage signals output by the top and bottom delta spiral detection coils in each double-layer triangular spiral flexible coil measurement module. After passing through channel selection, impedance transformation, pre-amplification, differential amplification, signal filtering, analog-to-digital conversion, digital phase-locked demodulation, and calibration, the stable output voltage change of each double-layer triangular spiral flexible coil measurement module in two orthogonal detection directions is obtained. The spatial force reconstruction module is used to jointly calculate and reconstruct the external forces within the test area based on the output voltage change, spatial position information, and pre-calibrated spatial response matrix of each double-layer triangular spiral flexible coil measurement module, so as to obtain the magnitude, position, and spatial distribution of the external forces.

[0009] Furthermore, the magnetostrictive sensitive layer is made of one or more of the following: iron-gallium alloy, iron-cobalt alloy, iron-nickel alloy, nickel, iron-silicon-boron amorphous alloy, iron-cobalt-silicon-boron amorphous alloy, iron-based nanocrystalline alloy, terbium-dysprosium-iron alloy, or magnetostrictive flexible composite material; the thickness of the magnetostrictive sensitive layer is 10 μm to 2 mm.

[0010] Furthermore, several of the double-layer triangular spiral flexible coil measurement modules are evenly arranged on the surface of the area to be measured at equal intervals to form a one-dimensional linear array, a two-dimensional surface array, or a spatial curved surface array; when arranged as a two-dimensional surface array, the double-layer triangular spiral flexible coil measurement modules are evenly distributed in rectangular, circular, or annular areas.

[0011] Furthermore, the traces of the top-layer and bottom-layer triangular spiral detection coils are arranged in a triangular spiral shape. Both the top-layer and bottom-layer triangular spiral detection coils are manufactured using flexible printed circuit technology, forming planar triangular spiral windings mounted on a flexible insulating substrate. Each planar triangular spiral winding consists of two oppositely arranged isosceles right-angled triangular spiral sub-coils, which are continuously wound from the outside in and connected in series through vias and connecting traces located inside the triangles, thereby forming a continuous conductive loop with input and output terminals. The top-layer and bottom-layer triangular spiral detection coils are rotated 90° relative to each other in the planar projection direction, making the main sensitive directions of the two detection coils orthogonal to each other, and are used to detect the force-magnetic response signals in two orthogonal directions within the test area.

[0012] Furthermore, the excitation module includes an excitation signal generation unit, an amplitude-frequency adjustment unit, a power drive unit, a multi-channel excitation allocation unit, and a sampling feedback and amplitude stabilization unit. The excitation signal generation unit generates a sinusoidal reference signal of a preset frequency. The amplitude-frequency adjustment unit adjusts the frequency and amplitude of the sinusoidal reference signal. The power drive unit amplifies the amplitude-frequency adjusted sinusoidal reference signal to obtain a sinusoidal excitation signal. The multi-channel excitation allocation unit synchronously outputs the amplified sinusoidal excitation signal to the excitation coils of each double-layer triangular spiral flexible coil measurement module. The sampling feedback and amplitude stabilization unit collects the actual excitation voltage or actual excitation current of the excitation coil and adjusts the sinusoidal excitation signal based on the collection results to maintain the frequency and amplitude of the sinusoidal excitation signal stable.

[0013] Furthermore, the signal acquisition and processing module includes a multi-channel acquisition and gating unit, an impedance matching and pre-amplifier conditioning unit, a differential amplifier unit, a filtering unit, an analog-to-digital converter unit, a digital phase-locked demodulation unit, and a calibration and data output unit; The multi-channel acquisition and selection unit is used to acquire the detection voltage signals output by the top and bottom triangular spiral detection coils in each double-layer triangular spiral flexible coil measurement module, and establish a correlation between the acquired detection voltage signals and the corresponding double-layer triangular spiral flexible coil measurement module and detection direction based on the spatial position coordinates of each double-layer triangular spiral flexible coil measurement module in the area to be measured. The impedance matching and pre-conditioning unit is used to perform impedance transformation and pre-amplification on each of the detected voltage signals to achieve impedance matching and improve the signal-to-noise ratio. The differential amplifier unit is used to differentially amplify each detection voltage signal after impedance transformation and pre-amplification in order to suppress common-mode interference, enhance the differential signal, and increase the amplitude of the detection voltage signal. The filtering unit is used to perform signal filtering on each detected voltage signal after differential amplification in order to filter out noise signals other than the excitation frequency. The analog-to-digital conversion unit is used to convert each channel of analog detection voltage signal obtained after filtering into a digital detection voltage signal. The digital phase-locked demodulation unit is used to demodulate each digital detection voltage signal in phase and quadrature using the sinusoidal excitation signal generated by the excitation module as a reference signal, to obtain the voltage amplitude and phase information corresponding to each double-layer triangular spiral flexible coil measurement module, and then to obtain the output voltage change of each double-layer triangular spiral flexible coil measurement module in two orthogonal detection directions under stress. The calibration and data output unit is used to perform zero-point calibration, amplitude calibration, phase calibration and channel consistency calibration on the output voltage changes of each double-layer triangular spiral flexible coil measurement module obtained by the digital phase-locked demodulation unit, and output the calibration results to the spatial force reconstruction module.

[0014] Furthermore, the spatial force reconstruction module is used to perform the following steps: Discretize the region to be measured into Each spatial reconstruction node is used to construct a structure containing the nodes at each location. direction and The force vector to be solved for the directional force components ; Based on the position coordinates, comprehensive sensitivity coefficient, and spatial position weighting function of each double-layer triangular spiral flexible coil measurement module, an array output vector is constructed. With the force vector to be solved Spatial response matrix between Satisfying the relation ,in This is the zero-point bias vector; Based on the array output vector and spatial response matrix Invert and reconstruct the spatially distributed forces within the area to be measured: ;in, To reconstruct the spatially distributed force vector, This is the weight matrix. The regularization coefficient is . This is the constraint matrix; Spatial distributed force vectors obtained from reconstruction Extract each spatial reconstruction node. directional force components and The directional force components are used to obtain the spatial distribution of external forces within the area to be measured.

[0015] Furthermore, when a concentrated force with an unknown location exists within the area to be measured, the spatial force reconstruction module is also used for: Construction and candidate action sites Related response matrix ; By traversing or optimizing the search, the location that minimizes the error between the theoretical and actual output is found, thus obtaining the estimated location of the concentrated force: ;in, For the candidate action position The relevant response matrix, Location of action External forces acting at the location; Based on the estimated location of action Corresponding response matrix Calculate the force components at that location: ; from The external force is obtained in directional force components and directional force components The force components are synthesized to obtain the estimated location of action. The magnitude of the external force: .

[0016] The objective of this invention can also be achieved through the following technical solutions.

[0017] A spatially distributed force measurement method based on a flexible coil array, implemented using the aforementioned device, includes the following steps: S1, n double-layer triangular spiral flexible coil measurement modules are evenly installed near the area to be measured. A stable sinusoidal excitation signal is applied to the excitation coil of each double-layer triangular spiral flexible coil measurement module through the excitation module to generate an alternating magnetic field near the magnetostrictive sensitive layer. S2, When an external force is applied to the area to be measured, the magnetic permeability of the magnetostrictive sensitive layer changes with the local stress, causing changes in the output voltage signals of the top-layer triangular spiral detection coil and the bottom-layer triangular spiral detection coil in each double-layer triangular spiral flexible coil measurement module; S3, through the signal acquisition and processing module, acquires the detection voltage signals output by the top and bottom delta spiral detection coils in each double-layer triangular spiral flexible coil measurement module, and sequentially performs channel selection, impedance transformation, pre-amplification, differential amplification, signal filtering, analog-to-digital conversion, digital phase-locked demodulation, and multi-parameter calibration to obtain the stable output voltage change of each double-layer triangular spiral flexible coil measurement module in two orthogonal detection directions; S4, through the spatial force reconstruction module, based on the output voltage change, spatial position information, and pre-calibrated spatial response matrix of each double-layer triangular spiral flexible coil measurement module, performs joint calculation and reconstruction of the external forces in the area to be measured, and obtains the magnitude, position, and spatial distribution of the external forces in the area to be measured.

[0018] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: (1) Advanced sensing mechanism, excellent direction recognition and sensitivity This invention is based on the principle of force-magnetic coupling, utilizing the characteristic that external stress causes changes in the magnetic permeability of magnetostrictive materials to convert mechanical quantities into easily detectable electromagnetic signals. Simultaneously, the detection coil employs a triangular spiral flexible coil structure; its unique triangular spiral routing can create a high magnetic field concentration within a limited area, improving detection sensitivity per unit area. Furthermore, by arranging two triangular spiral detection coils in mutually orthogonal directions, the mechanical responses in the x and y directions can be detected respectively, achieving high-precision two-dimensional orthogonal force measurement and effectively solving the problem that traditional unidirectional sensors cannot distinguish multidimensional forces.

[0019] (2) The overall structure is flexible and has strong adaptability to curved surfaces. Each double-layer triangular spiral flexible coil measurement module is made on a flexible substrate, and the magnetostrictive sensitive layer can be made of flexible composite material or ultra-thin metal strip. This allows the entire measurement module to be fabricated as a completely flexible structure, which can not only be flatly attached to a plane or flexible substrate, but also conform to complex curved surface contours (such as robot joints, cylindrical grip surfaces, etc.), greatly expanding the application scope of this invention in the detection of force distribution on irregularly shaped structures.

[0020] (3) Achieving a leap from single-point detection to space-distributed measurement This invention arranges n double-layer triangular spiral flexible coil measurement units evenly at known positions to form a distributed measurement array. Through the physical and mathematical models constructed by formulas (1) to (21), a precise functional mapping relationship between the output signal of each measurement module, its spatial position, and the external force is established. This design successfully extends the two-dimensional force measurement capability of a single triangular spiral flexible coil probe to spatial distributed force measurement, enabling continuous acquisition of the distribution function relationship between force and spatial position within the measurement area, rather than only obtaining the force value at discrete points.

[0021] (4) Excellent spatial calculation capability, and comprehensive and continuous measurement results. Using the position coordinates and output signals of each measurement module, the spatial force reconstruction module performs joint calculations using formulas (20) to (24). This algorithm can not only accurately calculate the magnitude and location of the unknown concentrated force, but also invert the distributed load (force distribution cloud map) within the test area by discretizing the nodes. This reconstruction method based on the array output vector and spatial response matrix significantly improves the continuity of the measurement area and the spatial calculation capability, overcoming the "missed detection" problem caused by the excessively large point spacing of traditional sensor arrays.

[0022] (5) The signal processing link is complete and the anti-interference performance is excellent. The signal acquisition and processing module sequentially performs channel selection, impedance transformation, pre-amplification, differential amplification, signal filtering, analog-to-digital conversion, digital phase-locked demodulation, and multi-parameter calibration on the weak detection voltage signal. This link design effectively suppresses low-frequency environmental noise, power frequency interference, and the circuit's own temperature drift and zero-point offset. In particular, the digital phase-locked demodulation, using the original excitation signal as a reference, can extract effective amplitude information that strictly corresponds to the change in permeability from a strong noise background, ensuring the stability and high signal-to-noise ratio of the final output signal.

[0023] (6) The array configuration is flexible, and the engineering scalability and adaptability are strong. The number n, array spacing, and arrangement shape (such as one-dimensional linear array, two-dimensional rectangular / circular array, or spatial curved surface array) of the double-layer triangular spiral flexible coil measurement units can all be flexibly adjusted according to the geometric dimensions of the space to be measured and the required resolution. This modular and scalable design enables the invention to adapt to various engineering application scenarios of different scales, from tiny tactile probes to monitoring large structural components. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the principle of the spatially distributed force measurement device based on a flexible coil array according to the present invention.

[0025] Figure 2(a) is a schematic diagram of the structure and detection direction of the top triangular spiral detection coil in this invention.

[0026] Figure 2(b) is a schematic diagram of the structure and detection direction of the bottom triangular spiral detection coil in this invention.

[0027] Figure 2(c) is a schematic diagram of the orthogonal arrangement structure and detection direction of the top triangular spiral detection coil and the bottom triangular spiral detection coil in this invention.

[0028] Figure 3 This is a schematic diagram of the signal acquisition and processing module in this invention.

[0029] Figure 4 This is a schematic diagram of the spatially distributed force measurement structure of the present invention, which employs four double-layer triangular spiral flexible coil measurement modules.

[0030] Reference numerals: 1-Magnetostrictive sensitive layer, 2-Excitation coil, 3-Top triangular spiral detection coil, 4-Bottom triangular spiral detection coil, 5-Flexible substrate. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described below with reference to the accompanying drawings.

[0032] like Figure 1 As shown, the present invention is a spatially distributed force measurement device based on a flexible coil array, which mainly includes a double-layer triangular spiral flexible coil measurement module, an excitation module, a signal acquisition and processing module, and a spatial force reconstruction module.

[0033] In this invention, the number of the double-layer triangular spiral flexible coil measurement modules is n, where n is an integer greater than or equal to 2. Each double-layer triangular spiral flexible coil measurement module includes, from top to bottom, a magnetostrictive sensitive layer 1, an excitation coil 2, a top triangular spiral detection coil 3, a bottom triangular spiral detection coil 4, and a flexible substrate 5. The excitation coil 2 is used to generate an alternating magnetic field near the magnetostrictive sensitive layer 1, as shown in Figures 2(a) to 2(c). Each double-layer triangular spiral flexible coil measurement module adopts a bidirectional detection structure. The top triangular spiral detection coil 3 and the bottom triangular spiral detection coil 4 are arranged in mutually orthogonal directions and are used to detect the force-magnetic response signals in different directions, outputting detection voltage signals in different directions. Since the external force will change the magnetic permeability distribution inside the magnetostrictive sensitive layer, the output signal will change with the force state. By differentially detecting the output signals in the two directions, the force response information in the two orthogonal directions in the local area can be obtained.

[0034] Preferably, the magnetostrictive sensitive layer 1 is made of one or more of the following: iron-gallium alloy, iron-cobalt alloy, iron-nickel alloy, nickel, iron-silicon-boron amorphous alloy, iron-cobalt-silicon-boron amorphous alloy, iron-based nanocrystalline alloy, terbium-dysprosium-iron alloy, or magnetostrictive flexible composite material; the thickness of the magnetostrictive sensitive layer 1 is 10 μm to 2 mm. The magnetostrictive flexible composite material includes a flexible polymer matrix and magnetostrictive particles dispersed in the flexible polymer matrix; when the magnetostrictive sensitive layer 1 is a magnetostrictive metal film, alloy sheet, amorphous alloy strip, or nanocrystalline alloy strip, its thickness is 10 μm to 500 μm; when the magnetostrictive sensitive layer 1 is a magnetostrictive flexible composite material, its thickness is 0.1 mm to 2 mm.

[0035] The top-layer triangular spiral detection coil 3 and the bottom-layer triangular spiral detection coil 4 have a triangular spiral shape in their wiring. Both are manufactured using flexible printed circuit technology and are planar triangular spiral windings mounted on a flexible insulating substrate. The conductive wiring of both coils is a continuous triangular spiral shape. Each triangular spiral detection coil includes two opposing isosceles right-angled triangular spiral sub-coils, which are wound turn by turn from the outside in and electrically connected to each other through vias and connecting traces located inside the triangles, forming a continuous conductive loop with signal input and output terminals. This triangular spiral wiring increases the number of coil turns and the effective magnetic flux coupling area within a limited area, and gives the detection coil high directional sensitivity to magnetic field changes parallel to its isosceles right-angled sides.

[0036] The top-layer triangular spiral detection coil 3 and the bottom-layer triangular spiral detection coil 4 are respectively disposed in different flexible circuit layers that are insulated from each other. They are rotated 90° relative to each other in the planar projection direction, so that the main sensitive direction of the top-layer triangular spiral detection coil 3 is orthogonal to the main sensitive direction of the bottom-layer triangular spiral detection coil 4. The top-layer triangular spiral detection coil 3 is used to detect the force-magnetic response signal in a first direction, and the bottom-layer triangular spiral detection coil 4 is used to detect the force-magnetic response signal in a second direction orthogonal to the first direction; in this embodiment, the first direction is the x-direction, and the second direction is the y-direction. Through the orthogonal arrangement of the two detection coils, detection voltage signals in two orthogonal directions within the test area can be obtained respectively.

[0037] The conductive traces of the top-layer triangular spiral detection coil 3 and the bottom-layer triangular spiral detection coil 4 are preferably made of copper foil, which is patterned into triangular spiral conductive traces using flexible printed circuit board processing. The flexible insulating substrate supporting the conductive traces is preferably made of polyimide film or polyester film. An adhesive layer is provided between the conductive traces and the flexible insulating substrate, and a flexible insulating dielectric layer is provided between the top-layer triangular spiral detection coil 3 and the bottom-layer triangular spiral detection coil 4 to achieve electrical isolation between the two detection coils; an insulating covering film is provided on the outer surface of the conductive traces, and corresponding electrical connection areas are formed only at the signal input end, signal output end, and via connection position.

[0038] The top-layer triangular spiral detection coil 3 and the bottom-layer triangular spiral detection coil 4 can be fabricated on two flexible printed circuit boards and stacked sequentially in an orthogonal direction; alternatively, they can be integrated into different conductive layers of the same multi-layer flexible printed circuit board. When a multi-layer flexible printed circuit board structure is used, the top-layer triangular spiral detection coil 3 and the bottom-layer triangular spiral detection coil 4 are separated by a flexible insulating dielectric layer, and the signal input and output terminals of each detection coil are connected to an external signal acquisition and processing module via lead-out traces or vias.

[0039] In a preferred embodiment, the overall dimensions of the triangular spiral flexible planar coil are 20 mm × 20 mm, the number of turns is 14, the linewidth of the conductive trace is 0.1 mm, the line spacing between adjacent conductive traces is 0.2 mm, the copper foil thickness is 0.035 mm, and the interlayer distance between the top triangular spiral detection coil 3 and the bottom triangular spiral detection coil 4 is 0.05 mm. These parameters can balance coil mutual inductance, magnetic field strength, and flexible printed circuit processing requirements within a limited area. The coil dimensions, number of turns, linewidth, line spacing, conductive layer thickness, and interlayer distance can also be adjusted according to the size of the area to be measured, the measurement range, the spatial resolution, and the flexible printed circuit processing conditions, and are not limited to the specific values ​​mentioned above.

[0040] When the top-layer triangular helical detection coil 3 and the bottom-layer triangular helical detection coil 4 bend or conformally deform with the flexible substrate 5, their triangular helical conductive traces remain continuously conductive, allowing the double-layer triangular helical flexible coil measurement module to conform to the surface of a plane, curved surface, or flexible structure. Because the overall thickness of the flexible printed circuit is relatively small, the coupling distance between the detection coil and the magnetostrictive sensitive layer 1 can be reduced, and the detection coil's ability to pick up changes in the permeability of the magnetostrictive sensitive layer 1 can be improved. n double-layer triangular spiral flexible coil measurement modules are evenly arranged at equal intervals on the surface of the area to be measured, forming a one-dimensional linear array, a two-dimensional surface array, or a spatial curved surface array. When arranged as a two-dimensional surface array, the double-layer triangular spiral flexible coil measurement modules are evenly distributed in a rectangular, circular, or annular area. The n double-layer triangular spiral flexible coil measurement modules in the area to be measured are numbered, and the installation position of each double-layer triangular spiral flexible coil measurement module is associated with the corresponding signal acquisition channel. The position coordinates of the double-layer triangular spiral flexible coil measurement module in the area to be measured can be represented as: (1) In the formula, Indicates the first i The position coordinates of a double-layer triangular spiral flexible coil measurement module in the area to be measured.

[0041] Each double-layer triangular spiral flexible coil measurement module includes orthogonal... Directional triangular spiral detection coil (i.e., top triangular spiral detection coil 3) and The directional triangular spiral detection coil (i.e., the bottom triangular spiral detection coil 4) is used to detect the force-magnetic response signals in two orthogonal directions. The detection direction of each double-layer triangular spiral flexible coil measurement module... Recorded as: (2) According to formula (2), the top triangular spiral detection coil 3 and the bottom triangular spiral detection coil 4 are respectively assigned to Direction detection channel and Direction detection channel, thereby enabling the first Each double-layer triangular spiral flexible coil measurement module can output... direction and The direction of the detected voltage signal.

[0042] In this invention, the excitation module provides a sinusoidal excitation signal to the excitation coil 2 of each double-layer triangular spiral flexible coil measurement module, enabling the excitation coil 2 to generate a stable alternating magnetic field near the magnetostrictive sensitive layer 1. Preferably, the excitation module includes an excitation signal generation unit, an amplitude-frequency adjustment unit, a power drive unit, a multi-channel excitation distribution unit, and a sampling feedback and amplitude stabilization unit. The excitation signal generation unit generates a sinusoidal reference signal of a preset frequency. The amplitude-frequency adjustment unit adjusts the frequency and amplitude of the sinusoidal reference signal. The power drive unit amplifies the amplitude-frequency adjusted sinusoidal reference signal to obtain a sinusoidal excitation signal. The multi-channel excitation distribution unit synchronously outputs the amplified sinusoidal excitation signal to the excitation coils of each double-layer triangular spiral flexible coil measurement module. The sampling feedback and amplitude stabilization unit collects the actual excitation voltage or actual excitation current of the excitation coil and adjusts the sinusoidal excitation signal based on the collection results to maintain the stability of the frequency and amplitude of the sinusoidal excitation signal.

[0043] The incentive module sends to the first The excitation coil input of the double-layer triangular spiral flexible coil measurement module is a stable sinusoidal excitation voltage: (3) In the formula, For excitation voltage, For the excitation voltage amplitude, The excitation angular frequency is given. According to formula (3), the excitation module determines the excitation voltage amplitude. and excitation angular frequency A sinusoidal excitation voltage is provided to the corresponding excitation coil 2, and the sinusoidal excitation signal is used as a reference signal for the signal acquisition and processing module to perform phase-locked demodulation.

[0044] Due to the equivalent impedance of the excitation coil The sinusoidal excitation voltage input to excitation coil 2 is converted into the corresponding excitation current:

[0045] In the formula, For the first In each measurement module Excitation current within the directional triangular spiral flexible coil. For the first In each measurement module The amplitude of the excitation current inside the directional triangular spiral flexible coil. The phase difference is caused by the equivalent impedance of the excitation coil. According to formula (4), the input sinusoidal excitation voltage passes through the equivalent impedance of the triangular spiral flexible coil. Converted into excitation current And generate a phase difference During phase-locked demodulation and calibration, the signal acquisition and processing module processes the fixed phase difference caused by the equivalent impedance of the coil to extract a stable detection signal related to the external force.

[0046] Excitation current An alternating magnetic field is generated near the excitation coil. In each measurement module The magnetic field strength generated by a directional triangular spiral flexible coil can be expressed as:

[0047] In the formula, For the first A double-layer triangular spiral flexible coil measurement module The magnetic field conversion coefficient of the directional triangular spiral flexible coil is related to the number of turns, line width, line spacing, interlayer distance, and coupling gap between the coil and the magnetostrictive sensitive layer 1. According to formula (5), the excitation current... An alternating magnetic field is generated near the magnetostrictive sensitive layer 1. This provides a stable magnetic field for detecting changes in the permeability of the magnetostrictive sensitive layer 1.

[0048] When an external force is applied to the area to be measured When the test occurs, the flexible substrate 5 within the test area undergoes localized deformation, causing a corresponding stress change in the magnetostrictive sensitive layer 1. This stress change alters the permeability of the magnetostrictive sensitive layer 1 through force-magnetic coupling. (Location of the test area) Place Change in directional permeability and The relationship between directional stresses is as follows:

[0049] In the formula, Location of the area to be measured Place The change in permeability in the direction of for Directional stress, Let be the stress-permeability conversion coefficient. According to formula (6), the stress change caused by the external force can be converted into a permeability change in the magnetostrictive sensitive layer 1, and within the small-signal linear operating range, the permeability change is... With stress The relationship is approximately linear.

[0050] Stress is generated by external forces and satisfies:

[0051] In the formula, Location of the area to be measured place External forces acting in the direction of the force This is the force-stress conversion coefficient. According to formula (7), the external force... The location of the test area is converted using the flexible substrate 5. Stress in magnetostrictive sensitive layer 1 .

[0052] Combining equations (6) and (7), we obtain the relationship between the change in magnetic permeability and the external force:

[0053] According to formula (8), the external force After force-stress conversion and stress-permeability conversion, the change in permeability in the corresponding direction in the magnetostrictive sensitive layer 1 is induced. Thus, the mechanical information carried by the external force is converted into information about the change in magnetic permeability that can be detected by the triangular spiral detection coil.

[0054] When the magnetic permeability of the magnetostrictive sensitive layer 1 changes, the magnetic circuit coupling state between the excitation coil 2 and the top triangular spiral detection coil 3 and the bottom triangular spiral detection coil 4 changes, causing the top triangular spiral detection coil 3 and the bottom triangular spiral detection coil 4 to output detection voltage signals in the corresponding directions.

[0055] According to the law of electromagnetic induction, the first The output voltage of the double-layer triangular spiral flexible coil measurement module is caused by the change in the magnetic permeability of the magnetostrictive sensitive layer. The output voltage amplitude of the directional triangular spiral detection coil can be expressed as:

[0056] in, For the first A double-layer triangular spiral flexible coil measurement module The output voltage amplitude of the directional triangular spiral detection coil. For the first A double-layer triangular spiral flexible coil measurement module The equivalent number of turns of the directional triangular spiral detection coil. For the first A double-layer triangular spiral flexible coil measurement module The equivalent magnetic flux area of ​​the directional triangular spiral detection coil. For the first A double-layer triangular spiral flexible coil measurement module The equivalent permeability of the detection area of ​​the directional triangular spiral detection coil.

[0057] According to formula (9), at the excitation angular frequency Equivalent number of turns Equivalent magnetic flux area Magnetic field conversion coefficient and excitation current amplitude Under certain circumstances, the first A double-layer triangular spiral flexible coil measurement module Output voltage amplitude of the directional triangular spiral detection coil With the equivalent permeability of the detection area It changes with the changes.

[0058] In this invention, the signal acquisition and processing module is used to acquire the detection voltage signals output by the top triangular spiral detection coil 3 and the bottom triangular spiral detection coil 4 in each double-layer triangular spiral flexible coil measurement module. After passing through channel selection, impedance transformation, pre-amplification, differential amplification, signal filtering, analog-to-digital conversion, digital phase-locked demodulation, and calibration, the stable output voltage change of each double-layer triangular spiral flexible coil measurement module in two orthogonal detection directions is obtained.

[0059] Preferably, such as Figure 3 As shown, the signal acquisition and processing module mainly includes a multi-channel acquisition and gating unit, an impedance matching and pre-stage conditioning unit, a differential amplification unit, a filtering unit, an analog-to-digital conversion unit, a digital phase-locked demodulation unit, and a calibration and data output unit.

[0060] The multi-channel acquisition and selection unit is used to acquire the detection voltage signals output by the top-layer triangular spiral detection coil 3 and the bottom-layer triangular spiral detection coil 4 in each double-layer triangular spiral flexible coil measurement module. Based on the spatial position coordinates of each double-layer triangular spiral flexible coil measurement module in the test area determined by formula (1), the acquired detection voltage signals are compared with the corresponding double-layer triangular spiral flexible coil measurement module and the detection direction determined by formula (2). Establish a correlation and identify the channel for each detected voltage signal.

[0061] The impedance matching and pre-amplification unit is used to perform impedance transformation and pre-amplification on each of the detection voltage signals output by the multi-channel acquisition and gating unit to achieve impedance matching and improve the signal-to-noise ratio. The impedance matching and pre-amplification unit mainly includes an impedance matching circuit and a pre-amplification circuit. The impedance matching circuit is used to achieve impedance matching between the triangular spiral detection coil and the subsequent signal processing circuit, reduce the influence of the subsequent circuit on the output state of the triangular spiral detection coil, and stably transmit the detection voltage signal output by the triangular spiral detection coil to the pre-amplification circuit. The impedance transformation process does not change the correspondence between the detection voltage signal and the equivalent permeability of the magnetostrictive sensitive layer 1, so that the signal after impedance transformation still represents the output voltage amplitude shown in formula (9). The detected voltage signal, after impedance transformation, is input to the pre-amplifier circuit. The pre-amplifier circuit amplifies the weak detected voltage signals output by the top-layer triangular spiral detection coil 3 and the bottom-layer triangular spiral detection coil 4, increasing the amplitude of the detected voltage signal to meet the processing requirements of subsequent differential amplification, signal filtering, analog-to-digital conversion, and phase-locked demodulation. For n double-layer triangular spiral flexible coil measurement modules, the signal acquisition and processing module respectively processes the signals of each double-layer triangular spiral flexible coil measurement module. Direction detection voltage signal and The direction detection voltage signal is amplified in the pre-amplifier stage, and calibration is performed to ensure that the signal amplification results of different measurement modules and different detection directions can be compared and jointly calculated.

[0062] The differential amplifier unit is used to differentially amplify each detection voltage signal after impedance transformation and pre-amplification to suppress common-mode interference, enhance the differential signal, and increase the amplitude of the detection voltage signal. Specifically, the pre-amplified detection voltage signal is input to the differential amplifier unit, which attenuates the initial voltage formed by the direct coupling of the excitation magnetic field, the common-mode signal generated by environmental interference, and the common drift in the detection circuit, and enhances the detection voltage change corresponding to the change in permeability of the magnetostrictive sensitive layer 1 caused by external forces. The top triangular spiral detection coil 3 and the bottom triangular spiral detection coil 4 are arranged in mutually orthogonal directions, and are retained after differential amplification. direction and The force-magnetic response signal in the direction enables the signal acquisition and processing module to obtain the detection results of the same double-layer triangular spiral flexible coil measurement module in two orthogonal directions.

[0063] The filtering unit is used to perform signal filtering on each detection voltage signal after differential amplification to remove noise signals other than the excitation frequency. Specifically, the detection voltage signal after differential amplification is input to the filtering unit, which is used to filter out DC drift, low-frequency interference, high-frequency noise, and signal components unrelated to the excitation signal frequency in the detection voltage signal, retaining the effective detection signal corresponding to the sinusoidal excitation signal shown in formula (3). After signal filtering, the effective response caused by external force in the detection voltage signal is retained, and noise and interference unrelated to external force are attenuated, thereby improving the stability of subsequent analog-to-digital conversion and phase-locked demodulation.

[0064] The analog-to-digital conversion unit converts each analog detection voltage signal obtained after signal filtering into a digital detection voltage signal. The signal acquisition and processing module synchronously acquires the digital detection voltage signals according to the numbering and detection direction of each double-layer triangular spiral flexible coil measurement module, and correlates each digital detection voltage signal with the corresponding measurement module position. and detection direction Related.

[0065] The digital phase-locked demodulation unit uses the sinusoidal excitation signal generated by the excitation module in formula (3) as a reference signal to perform phase-locked demodulation on each digital detection voltage signal, including in-phase demodulation and quadrature demodulation, and extracts the detection voltage signal with the same frequency and stable phase relationship as the sinusoidal excitation signal. It obtains the voltage amplitude and phase information corresponding to each double-layer triangular spiral flexible coil measurement module, and then obtains the output voltage change of each double-layer triangular spiral flexible coil measurement module in two orthogonal detection directions under stress.

[0066] According to formula (4), there is a phase difference between the excitation current and the excitation voltage caused by the equivalent impedance of the coil. During phase-locked demodulation, the phase difference of each detection channel is calibrated according to the phase relationship reflected in formula (4) to obtain the first phase difference. In a double-layer triangular spiral flexible coil measurement module Stable output voltage amplitude of the directional triangular spiral detection coil .

[0067] Before measuring external forces, the signal acquisition and processing module acquires the output voltage of each double-layer triangular spiral flexible coil measurement module under no external force conditions, and then processes the output voltage of the first module. In a double-layer triangular spiral flexible coil measurement module The output voltage of the directional triangular spiral detection coil under no external force condition is recorded as follows: When an external force is applied to the area under test, the signal acquisition and processing module follows the same process of channel selection, impedance transformation, pre-amplification, differential amplification, signal filtering, analog-to-digital conversion, and digital phase-locked demodulation to obtain the signal under the applied force. In a double-layer triangular spiral flexible coil measurement module Output voltage of the directional triangular spiral detection coil So, the first... In a double-layer triangular spiral flexible coil measurement module The change in output voltage of the triangular spiral detection coil before and after being subjected to force for:

[0068] According to formula (10), the signal acquisition and processing module will output the voltage under stress. Output voltage under no external force By comparison, the change in output voltage can be obtained. Output voltage change This is used to characterize the change in permeability of the magnetostrictive sensitive layer 1 caused by external forces, and to reduce the influence of the initial output voltage of the coil and the fixed zero-point signal on the force measurement results.

[0069] The calibration and data output unit measures the output voltage change of each double-layer triangular spiral flexible coil measurement module obtained by the digital phase-locked demodulation unit according to formula (10). The calibration process includes zero-point calibration, amplitude calibration, phase calibration, and channel consistency calibration to correct sensitivity differences and zero-point bias between different triangular spiral detection coils. The calibration results are then output to the spatial force reconstruction module.

[0070] Since the change in magnetic permeability is approximately linearly related to the change in output voltage, therefore the first In a double-layer triangular spiral flexible coil measurement module The relationship between the change in output voltage of the directional triangular spiral detection coil and the change in equivalent permeability is as follows:

[0071] In the formula, This is the voltage sensitivity coefficient. For zero-point offset term, For the first A double-layer triangular spiral flexible coil measurement module The change in equivalent permeability within the detection area of ​​the directional triangular spiral detection coil. According to formula (11), the voltage sensitivity coefficient... and zero-point offset term The data is obtained through pre-calibration. During calibration, while keeping the excitation signal, coil mounting position, and coupling gap constant, the output voltage of the detection channel is first acquired when the permeability of the magnetostrictive sensitive layer has not changed, thus obtaining zero-point calibration data. Subsequently, multiple known equivalent permeability changes are generated in the magnetostrictive sensitive layer, and the corresponding output voltage changes are acquired respectively. According to formula (11), the voltage sensitivity coefficient is obtained by linearly fitting multiple sets of equivalent permeability changes with the output voltage changes. and zero-point offset term The known change in equivalent permeability is measured using a permeability measuring device. The resulting voltage sensitivity coefficient... and zero-point offset term For the change in output voltage Calibration is performed so that the change in output voltage after calibration can reflect the change in equivalent permeability within the corresponding detection area. .

[0072] Each double-layer triangular spiral flexible coil measurement module has a corresponding detection range. The influence of external forces at the same location on the output signals of different double-layer triangular spiral flexible coil measurement modules varies. Therefore, after obtaining the output voltage change of each double-layer triangular spiral flexible coil measurement module, a spatial position weighting function is introduced to describe the positional influence of the external force.

[0073] Considering the varying sensitivity of the double-layer triangular spiral flexible coil measurement module to different spatial positions, a spatial position weighting function is introduced. Then the first The change in equivalent permeability detected by the double-layer triangular spiral flexible coil measurement module is:

[0074] According to formula (12), spatial location Change in permeability at point Through spatial location weight function Acting on the location The first A double-layer triangular spiral flexible coil measurement module. Spatial position weighting function. Used to indicate spatial location The change in permeability at point 1 affects the first The influence of the output signals of the double-layer triangular spiral flexible coil measurement module. The signal acquisition and processing module sends the calibrated output voltage change of each measurement module to the spatial force reconstruction module. The spatial force reconstruction module combines the spatial position weight relationship shown in formula (12) to jointly process the output signals of different measurement modules.

[0075] By combining the relationship of permeability change caused by external force with the relationship of equivalent permeability change detected by the double-layer triangular spiral flexible coil measurement module, substituting formula (8) into formula (12), and combining with formula (11), the first... A double-layer triangular spiral flexible coil measurement module The relationship between the change in directional output voltage and the spatially distributed force within the measured region:

[0076] In the formula, , indicating the first A double-layer triangular spiral flexible coil measurement module The overall sensitivity coefficient of the direction; This represents a spatial location weighting function, used to describe the location of... The force at the location is located The degree of influence of the output signal of the double-layer triangular spiral flexible coil measurement module at the location; = , indicating the first A double-layer triangular spiral flexible coil measurement module The zero-point offset term of the direction detection channel. According to formula (13), the first... A double-layer triangular spiral flexible coil measurement module Directional output voltage change From the area to be tested Direction of external force Comprehensive sensitivity coefficient Spatial location weight function and zero-point offset term To be determined jointly.

[0077] For a single concentrated force acting at a position In this case, formula (13) can be simplified to: (14) This equation shows that, under stable excitation conditions, the first... A double-layer triangular spiral flexible coil measurement module Directional output voltage change With external forces Component magnitude in direction The relationship is approximately linear, and the location is subject to concentrated force. With measurement module position Spatial position weight function The effect of concentrated force on a double-layer triangular spiral flexible coil measurement module is that when a concentrated force approaches the module, the spatial position weighting function value of that module changes accordingly, resulting in a difference in the output voltage change between that module and other measurement modules.

[0078] The signal acquisition and processing module will The output voltage changes obtained from the double-layer triangular spiral flexible coil measurement modules after channel selection, impedance transformation, pre-amplification, differential amplification, signal filtering, analog-to-digital conversion, digital phase-locked demodulation, and calibration are arranged according to the measurement module number and detection direction to form an array output vector. The output voltage changes of the measurement modules consisting of double-layer triangular spiral flexible coils form an array output vector:

[0079] In the formula, Indicates the first In a double-layer triangular spiral flexible coil measurement module The change in output voltage of the directional triangular spiral detection coil; Indicates the first In a double-layer triangular spiral flexible coil measurement module The change in output voltage of the directional triangular helix detection coil. According to the above formula, the array output vector ΔU contains the measurement module of each double-layer triangular helix flexible coil. direction and The change in output voltage in the direction. The signal acquisition and processing module transmits the array output vector ΔU to the spatial force reconstruction module.

[0080] When the signal acquisition and processing module uses the output current as the detection quantity, if the equivalent load impedance of the detection end is Then the first A double-layer triangular spiral flexible coil measurement module The change in output current in the direction is:

[0081] Right now:

[0082] in, = , representing the current sensitivity coefficient; Indicates the first A double-layer triangular spiral flexible coil measurement module The zero-point bias term of the directional current detection channel. Therefore, it can be seen that a linear relationship can be established between the external force and the change in output voltage or output current.

[0083] In this invention, the spatial force reconstruction module is used to jointly calculate and reconstruct the external forces within the test area based on the output voltage change, spatial position information, and pre-calibrated spatial response matrix of each double-layer triangular spiral flexible coil measurement module, so as to obtain the magnitude, position, and spatial distribution of the external forces within the test area.

[0084] To achieve spatially distributed force measurement, after completing the signal acquisition, processing, and calibration of each double-layer triangular spiral flexible coil measurement module, the spatial force reconstruction module discretizes the measurement area into... Each spatial reconstruction node has a location coordinate:

[0085] From the above formula, we can see that the first [unit] in the region to be measured... The location of each spatial reconstruction node is determined by The spatial force reconstruction module indicates the position of each spatial reconstruction node. Position of each double-layer triangular spiral flexible coil measurement module Together they are used to establish the spatial mapping relationship between external forces and array output signals.

[0086] Each spatial reconstruction node includes directional force components and The directional force components and spatial force reconstruction module combine the force components at all spatial reconstruction nodes into a force vector to be solved. : (19) In the formula, Indicates the first Spatial Reconstruction Nodes External forces at the point of application Force component in the direction; Indicates the first Spatial Reconstruction Nodes External forces at the point of application The force component in the direction. According to the above equation, the force vector to be solved is... Includes the spatial reconstruction nodes within the area to be tested. directional force components and Directional force components. The spatial force reconstruction module solves for the force vector to be solved. This allows us to obtain the spatially distributed forces within the area to be measured.

[0087] Based on formula (13), establish the array output vector. With the force vector to be solved The spatial response relationship between them can be expressed as follows: The voltage change array output of each double-layer triangular spiral flexible coil measurement module and the spatially distributed force can be expressed as:

[0088] In the formula, The spatial response matrix, This is the zero-point bias vector. (Matrix) The elements in the equation are determined by the position of each double-layer triangular spiral flexible coil measurement module, the overall sensitivity coefficient, and the spatial position weighting function, and can be expressed as:

[0089] In the formula, Indicates the first Spatial Reconstruction Nodes Directional force on the first A double-layer triangular spiral flexible coil measurement module The influence coefficient of directional output voltage.

[0090] As can be seen from the above equation, the array output vector ΔU is derived from the spatial response matrix. The force vector to be solved and zero-point bias vector Determined jointly. The spatial force reconstruction module uses the spatial response matrix. Establish the correspondence between the force components at each spatial reconstruction node and the output voltage change of each double-layer triangular spiral flexible coil measurement module, i.e., formula (20).

[0091] The top triangular spiral detection coil 3 and the bottom triangular spiral detection coil 4 are used for detection. direction and The force-magnetic response signal in the direction. To consider... , The spatial force reconstruction module handles potential cross-coupling between directions according to the matrix response relationship between the two directions. A double-layer triangular spiral flexible coil measurement module direction and Directional output voltage change and at each spatial reconstruction node Directional force and The relationships between directional forces are as follows, represented by the following matrix:

[0092] In the formula, Indicates the first A double-layer triangular spiral flexible coil measurement module The change in output voltage of the direction detection channel; Indicates the first A double-layer triangular spiral flexible coil measurement module The change in output voltage of the direction detection channel; Indicates the first The spatial coordinates of a double-layer triangular spiral flexible coil measurement module in the area to be measured; Indicates the first The location coordinates of each spatial reconstruction node; Indicates the first External forces at each spatial reconstruction node Force component in the direction; Indicates the first External forces at each spatial reconstruction node Force components in the direction. Indicates the first In a double-layer triangular spiral flexible coil measurement module Zero-point offset term of the direction detection channel, Indicates the first In a double-layer triangular spiral flexible coil measurement module The zero-point offset term of the direction detection channel is used to characterize the residual output offset that still exists in the detection channel when there is no external force or after zero-point calibration. Indicates the first A double-layer triangular spiral flexible coil measurement module Direction detection channel pair The overall sensitivity coefficient of the external force in the direction of action, i.e. Directional force acting on The same-direction force-voltage response sensitivity coefficient when using the direction detection channel; Indicates the first A double-layer triangular spiral flexible coil measurement module Direction detection channel pair The cross sensitivity coefficient of the external force in the direction of action, i.e. Directional force in The cross-directional force generated when the output voltage changes in the direction detection channel—voltage response sensitivity coefficient; Indicates the first A double-layer triangular spiral flexible coil measurement module Direction detection channel pair The cross sensitivity coefficient of the external force in the direction of action, i.e. Directional force The cross-directional force generated when the output voltage changes in the direction detection channel—voltage response sensitivity coefficient; Indicates the first A double-layer triangular spiral flexible coil measurement module Direction detection channel pair The overall sensitivity coefficient of the external force in the direction of action, i.e. Directional force acting on Force in the same direction during direction detection channel - voltage response sensitivity coefficient. Indicates that it is located at the th At each spatial reconstruction node Directional force on the first In a double-layer triangular spiral flexible coil measurement module Spatial position weighting function for the output voltage of the direction detection channel; Indicates that it is located at the th At each spatial reconstruction node Directional force on the first In a double-layer triangular spiral flexible coil measurement module Spatial position weighting function for the output voltage of the direction detection channel; Indicates that it is located at the th At each spatial reconstruction node Directional force on the first In a double-layer triangular spiral flexible coil measurement module Spatial position weighting function for the output voltage of the direction detection channel; Indicates that it is located at the th At each spatial reconstruction node Directional force on the first In a double-layer triangular spiral flexible coil measurement module The spatial position weighting function of the output voltage of the direction detection channel. The main diagonal term in this formula... and Represents the force-voltage response in the same direction, non-diagonal terms. and This represents the cross-directional coupling response. All the aforementioned sensitivity coefficients, spatial position weighting functions, and zero-point offset terms can be obtained through calibration. The spatial force reconstruction module can utilize the pre-calibrated sensitivity coefficients and spatial position weighting functions to... direction and The cross-coupling responses between directions are processed to obtain the results at each spatial reconstruction node. directional force components and Directional force component.

[0093] When the output current is used as the array detection quantity, the relationship between the change in array output current and the spatially distributed force can be expressed similarly as follows:

[0094] In the formula, This is the vector of changes in the array output current. The current response matrix is... This is the zero-point bias vector of the array output current. The spatial force reconstruction module can utilize the array output current change vector. and current response matrix To solve for the force vector Refactor.

[0095] Based on the array output vector and the pre-calibrated spatial response matrix It can invert and reconstruct spatially distributed forces within the area to be measured:

[0096] in, To reconstruct the spatially distributed force vector, This is the weight matrix. The regularization coefficient is . The constraint matrix is ​​given. Based on the above formula, the spatial force reconstruction module first uses the array output vector... and zero-point bias vector The array output signal after removing the zero-point bias is obtained, and then combined with the spatial response matrix. Weight matrix Regularization coefficient λ and constraint matrix The reconstructed spatial distributed force vector is obtained. .

[0097] Based on the force component arrangement shown in formula (19), the reconstructed spatially distributed force vector is obtained. The spatial reconstruction nodes are obtained sequentially. directional force components and The directional force components are used to obtain the spatial distribution of external forces within the area to be measured.

[0098] The signal acquisition and processing module sends the calibrated output voltage changes of each double-layer triangular spiral flexible coil measurement module to the spatial force reconstruction module. According to formula (12), the spatial force reconstruction module combines the position coordinates of each measurement module and the corresponding spatial position weight function to determine the degree of influence of the permeability change at different spatial positions in the test area on the output signal of each measurement module; according to formula (13), the response relationship between the output voltage change of each measurement module and the spatial distributed force in the test area is established.

[0099] When there is only one concentrated force in the area to be measured, and the concentrated force acts at a spatial location According to formula (14), the response relationship between the output voltage change in the q direction and the concentrated force direction component and its position in the i-th double-layer triangular spiral flexible coil measurement module is established. Since the positions of each measurement module are different, the output voltage change generated by the same concentrated force in different measurement modules is different. The output difference provides a basis for subsequent construction of array output vector, determination of concentrated force position, and calculation of concentrated force direction component.

[0100] When a concentrated force with an unknown location exists within the test area, the spatial force reconstruction module can also construct a response matrix related to the location of the concentrated force. The relationship between the array output voltage change and the unknown concentrated force is as follows:

[0101] In the formula, The location of the unknown concentrated force. For the position of action The relevant response matrix, Location of action External forces acting at the location.

[0102] Used to indicate the location where a concentrated force is applied. At that time, the concentration directional force components and Directional force components in all double-layer triangular spiral flexible coil measurement modules Direction detection channel and The influence of changes in the output voltage of the direction detection channel. That is:

[0103] According to the above formula, concentration force Depend on directional force components and directional force components composition.

[0104] The spatial force reconstruction module traverses or optimizes the search for possible concentrated force application locations within the test area, and calculates the theoretical array output signal corresponding to different candidate application locations. This allows us to obtain an estimated location of the unknown concentrated force:

[0105] This represents the estimated location of the unknown concentrated force, which is the candidate location within the test area that minimizes the error between the theoretical array output and the actual array output. For the candidate action position The relevant response matrix, Location of action The external forces acting at the location. Based on the above formula, the spatial force reconstruction module compares the theoretical array output signal with the actual array output vector at different candidate locations. The error between the theoretical and actual outputs is determined, and the position that minimizes the error between the theoretical and actual outputs is identified as the estimated position of the external concentrated force. .

[0106] The estimated location of the external concentrated force is determined according to formula (27). Subsequently, the spatial force reconstruction module utilizes the array output vector Zero-point bias vector The response matrix corresponding to the estimated action location. and weight matrix The estimated location of action is calculated. External forces at the location :

[0107] According to the force component composition shown in formula (26), from The external force is obtained in directional force components and directional force components By combining the force components in these two orthogonal directions, the estimated location of action can be obtained. The magnitude of the external force:

[0108] The above formula shows that in this invention, the input excitation voltage is converted into an excitation current through the coil impedance, and the excitation current generates an alternating magnetic field; the external force changes the permeability of the magnetostrictive sensitive layer, and the change in permeability further causes changes in the output voltage or output current; within the small signal linear operating range, the change in output voltage or output current is linearly related to the external force, and is associated with the position of the force through a spatial position function.

[0109] Based on the above principles, this invention also proposes a spatially distributed force measurement method based on a flexible coil array, which mainly includes the following steps: S1, n double-layer triangular spiral flexible coil measurement modules are evenly installed near the area to be measured. A stable sinusoidal excitation signal is applied to the excitation coil 2 of each double-layer triangular spiral flexible coil measurement module through the excitation module to generate an alternating magnetic field near the magnetostrictive sensitive layer 1. S2, When an external force is applied to the area to be measured, the magnetic permeability of the magnetostrictive sensitive layer 1 changes with the local stress, causing changes in the output voltage signal of the top triangular spiral detection coil 3 and the bottom triangular spiral detection coil 4 in each double-layer triangular spiral flexible coil measurement module; S3, the signal acquisition and processing module acquires the detection voltage signals output by the top triangular spiral detection coil 3 and the bottom triangular spiral detection coil 4 in each double-layer triangular spiral flexible coil measurement module, and sequentially performs channel selection, impedance transformation, pre-amplification, differential amplification, signal filtering, analog-to-digital conversion, digital phase-locked demodulation and multi-parameter calibration to obtain the stable output voltage change of each double-layer triangular spiral flexible coil measurement module in two orthogonal detection directions; S4, through the spatial force reconstruction module, based on the output voltage change, spatial position information, and pre-calibrated spatial response matrix of each double-layer triangular spiral flexible coil measurement module, performs joint calculation and reconstruction of the external forces in the area to be measured, and obtains the magnitude, position, and spatial distribution of the external forces in the area to be measured.

[0110] like Figure 4 As shown, this embodiment employs four double-layer triangular spiral flexible coil measurement modules for spatial distributed force measurement. The four modules are evenly arranged at the four cardinal points of the area to be measured, maintaining the same installation height and detection spacing, for distributed detection of external forces within the area. When an external force is applied to the area above or on its surface, the modules at different positions will generate output signals with different amplitudes and directional characteristics. The output of the modules closer to the applied force location shows more significant changes, while the output of those farther away shows relatively smaller changes. By comparing the output differences of the four modules, the location and magnitude of the external force within the area to be measured can be determined.

[0111] First, four flexible coil sensing units are evenly installed around the area to be measured, ensuring that the detection direction of each double-layer triangular spiral flexible coil measurement module remains consistent. After installation, the initial signal of each double-layer triangular spiral flexible coil measurement module is acquired under no external force, and this initial signal is used as the zero-point reference. Then, multiple known locations are selected within the area to be measured, and a standard force of known magnitude is applied to each. The output signals of the four double-layer triangular spiral flexible coil measurement modules are recorded under different loading positions and magnitudes, forming a calibration dataset. The calibration dataset includes at least the position coordinates of each double-layer triangular spiral flexible coil measurement module. Coordinates of each standard force loading position The magnitude of the standard force and its force components in the x and y directions; the initial output voltage of the x-direction and y-direction detection channels in each measurement module without external force; the output voltage of each detection channel after the standard force is applied; and the change in output voltage calculated based on the output voltage before and after the force is applied.

[0112] After calibration, unknown external force measurements can be performed. When an unknown external force acts on the area to be measured, the four double-layer triangular spiral flexible coil measurement modules synchronously acquire signals. The signal acquisition and processing module sequentially performs channel selection, impedance transformation, pre-amplification, differential amplification, signal filtering, analog-to-digital conversion, digital phase-locked demodulation, and multi-parameter calibration on the detection voltage signals output by the four double-layer triangular spiral flexible coil measurement modules, obtaining the stable output voltage changes of the four double-layer triangular spiral flexible coil measurement modules in two orthogonal detection directions, and inputs them all into the spatial force reconstruction module. The spatial force reconstruction module determines the spatial position and force magnitude corresponding to the current output signal based on the spatial position information of the four double-layer triangular spiral flexible coil measurement modules and the pre-calibrated calibration dataset, and finally outputs the force distribution results within the area to be measured. This result can be displayed on the host computer as force magnitude value, force position coordinates, force direction information, or force distribution cloud map.

[0113] The use of four double-layer triangular spiral flexible coil measurement modules in this embodiment is merely to illustrate a preferred implementation of the invention and does not constitute a limitation on the scope of protection of the invention. In practical applications, more double-layer triangular spiral flexible coil measurement modules can be set according to the shape of the area to be measured and the measurement accuracy requirements. The double-layer triangular spiral flexible coil measurement module array can also be arranged in a circular, rectangular, annular, curved, or other form adapted to the structure to be measured. As long as multiple double-layer triangular spiral flexible coil measurement modules capable of detecting orthogonal force responses are used, and the spatially distributed force is reconstructed through the array output signal, all fall within the scope of protection of this invention.

[0114] Although the functions and working processes of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific functions and working processes described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these are within the protection scope of the present invention.

Claims

1. A spatially distributed force measurement device based on a flexible coil array, characterized in that, It includes several double-layer triangular spiral flexible coil measurement modules, excitation modules, signal acquisition and processing modules, and spatial force reconstruction modules; Each of the double-layer triangular spiral flexible coil measurement modules includes, from top to bottom, a magnetostrictive sensitive layer (1), an excitation coil (2), a top triangular spiral detection coil (3), a bottom triangular spiral detection coil (4), and a flexible substrate (5); the excitation coil (2) is used to generate an alternating magnetic field near the magnetostrictive sensitive layer (1); the top triangular spiral detection coil (3) and the bottom triangular spiral detection coil (4) are arranged in mutually orthogonal directions and are used to detect force and magnetic response signals in different directions and output detection voltage signals in different directions. The excitation module is used to provide a sinusoidal excitation signal to the excitation coil (2) of each double-layer triangular spiral flexible coil measurement module; The signal acquisition and processing module is used to acquire the detection voltage signals output by the top triangular spiral detection coil (3) and the bottom triangular spiral detection coil (4) in each double-layer triangular spiral flexible coil measurement module. After passing through channel selection, impedance transformation, pre-amplification, differential amplification, signal filtering, analog-to-digital conversion, digital phase-locked demodulation, and calibration, the stable output voltage change of each double-layer triangular spiral flexible coil measurement module in two orthogonal detection directions is obtained. The spatial force reconstruction module is used to jointly calculate and reconstruct the external forces within the test area based on the output voltage change, spatial position information, and pre-calibrated spatial response matrix of each double-layer triangular spiral flexible coil measurement module, so as to obtain the magnitude, position, and spatial distribution of the external forces.

2. The spatially distributed force measurement device based on a flexible coil array according to claim 1, characterized in that, The magnetostrictive sensitive layer (1) is made of one or more of the following: iron gallium alloy, iron cobalt alloy, iron nickel alloy, nickel, iron silicon boron amorphous alloy, iron cobalt silicon boron amorphous alloy, iron-based nanocrystalline alloy, terbium dysprosium iron alloy or magnetostrictive flexible composite material; the thickness of the magnetostrictive sensitive layer (1) is 10 μm to 2 mm.

3. The spatially distributed force measurement device based on a flexible coil array according to claim 1, characterized in that, Several of the aforementioned double-layer triangular spiral flexible coil measurement modules are evenly arranged on the surface of the area to be measured at equal intervals, forming a one-dimensional linear array, a two-dimensional surface array, or a spatial curved surface array; when arranged as a two-dimensional surface array, the double-layer triangular spiral flexible coil measurement modules are evenly distributed in rectangular, circular, or annular areas.

4. The spatially distributed force measurement device based on a flexible coil array according to claim 1, characterized in that, The top-layer triangular spiral detection coil (3) and the bottom-layer triangular spiral detection coil (4) are arranged in a triangular spiral shape. Both the top-layer triangular spiral detection coil (3) and the bottom-layer triangular spiral detection coil (4) are made using flexible printed circuit technology and are planar triangular spiral windings set on a flexible insulating substrate. Each planar triangular spiral winding consists of two isosceles right-angled triangular spiral sub-coils arranged opposite each other. The two isosceles right-angled triangular spiral sub-coils are continuously wound from the outside to the inside and are connected in series through vias and connecting traces set inside the triangle, thereby forming a continuous conductive circuit with an input end and an output end. The top-layer triangular spiral detection coil (3) and the bottom-layer triangular spiral detection coil (4) are rotated 90° relative to each other in the plane projection direction, so that the main sensitive directions of the two detection coils are orthogonal to each other, and are used to detect the force and magnetic response signals in the two orthogonal directions in the test area.

5. The spatially distributed force measurement device based on a flexible coil array according to claim 1, characterized in that, The excitation module includes an excitation signal generation unit, an amplitude-frequency adjustment unit, a power drive unit, a multi-channel excitation allocation unit, and a sampling feedback and amplitude stabilization unit. The excitation signal generation unit generates a sinusoidal reference signal at a preset frequency. The amplitude-frequency adjustment unit adjusts the frequency and amplitude of the sinusoidal reference signal. The power drive unit amplifies the amplitude-frequency adjusted sinusoidal reference signal to obtain a sinusoidal excitation signal. The multi-channel excitation allocation unit synchronously outputs the amplified sinusoidal excitation signal to the excitation coils of each double-layer triangular spiral flexible coil measurement module. The sampling feedback and amplitude stabilization unit collects the actual excitation voltage or actual excitation current of the excitation coil and adjusts the sinusoidal excitation signal based on the collection results to maintain the frequency and amplitude of the sinusoidal excitation signal stable.

6. The spatially distributed force measurement device based on a flexible coil array according to claim 1, characterized in that, The signal acquisition and processing module includes a multi-channel acquisition and gating unit, an impedance matching and pre-amplifier conditioning unit, a differential amplifier unit, a filtering unit, an analog-to-digital converter unit, a digital phase-locked demodulation unit, and a calibration and data output unit. The multi-channel acquisition and selection unit is used to acquire the detection voltage signals output by the top triangular spiral detection coil (3) and the bottom triangular spiral detection coil (4) in each double-layer triangular spiral flexible coil measurement module, and establish a correlation between the acquired detection voltage signals and the corresponding double-layer triangular spiral flexible coil measurement module and detection direction according to the spatial position coordinates of each double-layer triangular spiral flexible coil measurement module in the area to be measured. The impedance matching and pre-conditioning unit is used to perform impedance transformation and pre-amplification on each of the detected voltage signals to achieve impedance matching and improve the signal-to-noise ratio. The differential amplifier unit is used to differentially amplify each detection voltage signal after impedance transformation and pre-amplification in order to suppress common-mode interference, enhance the differential signal, and increase the amplitude of the detection voltage signal. The filtering unit is used to perform signal filtering on each detected voltage signal after differential amplification in order to filter out noise signals other than the excitation frequency. The analog-to-digital conversion unit is used to convert each channel of analog detection voltage signal obtained after filtering into a digital detection voltage signal. The digital phase-locked demodulation unit is used to demodulate each digital detection voltage signal in phase and quadrature using the sinusoidal excitation signal generated by the excitation module as a reference signal, to obtain the voltage amplitude and phase information corresponding to each double-layer triangular spiral flexible coil measurement module, and then to obtain the output voltage change of each double-layer triangular spiral flexible coil measurement module in two orthogonal detection directions under stress. The calibration and data output unit is used to perform zero-point calibration, amplitude calibration, phase calibration and channel consistency calibration on the output voltage changes of each double-layer triangular spiral flexible coil measurement module obtained by the digital phase-locked demodulation unit, and output the calibration results to the spatial force reconstruction module.

7. The spatially distributed force measurement device based on a flexible coil array according to claim 1, characterized in that, The spatial force reconstruction module is used to perform the following steps: Discretize the region to be measured into Each spatial reconstruction node is used to construct a structure containing the information at each node. direction and The force vector to be solved for the directional force components ; Based on the position coordinates, comprehensive sensitivity coefficient, and spatial position weighting function of each double-layer triangular spiral flexible coil measurement module, an array output vector is constructed. With the force vector to be solved Spatial response matrix between Satisfying the relation ,in This is the zero-point bias vector; Based on the array output vector and spatial response matrix Invert and reconstruct the spatially distributed forces within the area to be measured: ;in, To reconstruct the spatially distributed force vector, This is the weight matrix. The regularization coefficient is . This is the constraint matrix; Spatial distributed force vectors obtained from reconstruction Extract each spatial reconstruction node. directional force components and The directional force components are used to obtain the spatial distribution of external forces within the area to be measured.

8. The spatially distributed force measurement device based on a flexible coil array according to claim 7, characterized in that, When a concentrated force with an unknown location exists within the area to be measured, the spatial force reconstruction module is also used for: Construction and candidate action sites Related response matrix ; By traversing or optimizing the search, the location that minimizes the error between the theoretical and actual output is found, thus obtaining the estimated location of the concentrated force: ;in, For the candidate action position The relevant response matrix, Location of action External forces acting at the location; Based on the estimated location of action Corresponding response matrix Calculate the force components at that location: ; from The external force is obtained in directional force components and directional force components The force components are synthesized to obtain the estimated location of action. The magnitude of the external force: .

9. A spatially distributed force measurement method based on a flexible coil array, implemented using the device described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1, n double-layer triangular spiral flexible coil measurement modules are evenly installed near the area to be measured. A stable sinusoidal excitation signal is applied to the excitation coil (2) of each double-layer triangular spiral flexible coil measurement module through the excitation module to generate an alternating magnetic field near the magnetostrictive sensitive layer (1). S2, when an external force is applied to the area to be measured, the permeability of the magnetostrictive sensitive layer (1) changes with the local stress, causing changes in the output voltage signal of the top triangular spiral detection coil (3) and the bottom triangular spiral detection coil (4) in each double-layer triangular spiral flexible coil measurement module; S3, the detection voltage signals output by the top triangular spiral detection coil (3) and the bottom triangular spiral detection coil (4) in each double-layer triangular spiral flexible coil measurement module are acquired through the signal acquisition and processing module, and the channel selection, impedance transformation, pre-amplification, differential amplification, signal filtering, analog-to-digital conversion, digital phase-locked demodulation and multi-parameter calibration are performed in sequence to obtain the stable output voltage change of each double-layer triangular spiral flexible coil measurement module in two orthogonal detection directions; S4, through the spatial force reconstruction module, based on the output voltage change, spatial position information, and pre-calibrated spatial response matrix of each double-layer triangular spiral flexible coil measurement module, performs joint calculation and reconstruction of the external forces in the area to be measured, and obtains the magnitude, position, and spatial distribution of the external forces in the area to be measured.

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