A six-dimensional force sensor of four L-shaped elastic beam structure and a strain gauge arrangement method

Abstract

The application belongs to the technical field of strain type multi-dimensional force sensor, and discloses a six-dimensional force sensor with four L-shaped elastic beam structures and a strain gauge arrangement method, aiming to solve the core problems of strain dispersion, low sensitivity, serious inter-dimension coupling and large mechanical hysteresis of the existing six-dimensional force sensor. The elastic body is an integral structure, and the core includes an outer circular ring, a central loading platform and four L-shaped elastic beams connecting the two, the four L-shaped elastic beams are distributed at equal intervals of 90 degrees along the circumference of the outer circular ring, and the beam body is mainly subjected to directional bending deformation when loaded, so that a stable strain concentration area can be formed; 12 strain gauges are accurately attached to the maximum bending strain area of the beam body based on finite element simulation, and cooperate with the half-bridge double-working-piece Wheatstone bridge to realize six-dimensional force / torque measurement. The application can effectively reduce the inter-dimension coupling error and mechanical hysteresis, improve the measurement sensitivity and long-term stability, and is suitable for high-precision six-dimensional force measurement scenes such as industrial robot precision assembly, aerospace measurement and control, medical minimally invasive surgery and the like.

Description

[0001] This invention belongs to the field of strain-type multidimensional force sensor technology, specifically relating to a strain-type six-dimensional force sensor with a four-L-shaped elastic beam structure and a strain gauge arrangement method. It can be widely used in high-precision six-dimensional force / torque measurement scenarios such as precision assembly of industrial robots, aerospace measurement and control, minimally invasive medical surgery, and force feedback in intelligent manufacturing. Background Technology

[0002] The six-dimensional force sensor can simultaneously measure three-dimensional orthogonal force components (F) in a spatial rectangular coordinate system. x F y F z ) and three-dimensional orthogonal moment components (M x M y M z It is a core sensing element for realizing closed-loop force control and precise force detection, and plays an irreplaceable role in the field of high-end equipment manufacturing.

[0003] Among them, the resistance strain gauge six-dimensional force sensor has become the most widely used six-dimensional force sensing solution in industrial scenarios due to its advantages such as simple structure, low manufacturing cost, good measurement stability, and strong adaptability. Existing strain gauge six-dimensional force sensors mainly use cross-beam structures and their improved elastic bodies as the core mainstream structure. However, this type of structure has the following inherent defects in practical applications: First, the strain distribution is scattered, and it is impossible to form a stable and efficient strain concentration area in the local area of ​​the beam, resulting in the sensitivity of the sensor under rated load generally being less than 5 mV / V; Second, the coupling interference between the measurement dimensions is serious, and the inter-dimensional coupling error generally exceeds 5% FS. It is difficult to suppress the inter-dimensional coupling through structural design and requires compensation by complex nonlinear decoupling algorithms; Third, the force flow transmission path is complex, and there are obvious mechanical hysteresis and nonlinear response problems under high-frequency dynamic measurement conditions, making it impossible to simultaneously achieve high accuracy and high stability in six-dimensional force measurement.

[0004] Chinese patent CN117387821B discloses a six-dimensional force sensor composed of orthogonal flexible hinge plates. This scheme uses multiple sets of orthogonally arranged plate-type flexible hinges as the sensing structure, and sets strain measurement units in the weak areas of the flexible hinges. The strain signal is extracted by differential method, which improves the measurement accuracy to a certain extent and suppresses the interference of non-target strain. However, this scheme has a large number of flexible sensing units and a complex structure, which is prone to strain signal redundancy and error propagation. Moreover, the strain concentration area is not obvious, which limits the improvement of measurement sensitivity and makes it difficult to achieve high-precision decoupled measurement of six-dimensional force / torque.

[0005] Chinese patent CN109632159B discloses a six-dimensional force and torque sensor. This design uses a support frame and multiple elastic beams to form a sensitive structure, optimizing the shape of the elastic beams to balance the sensor's measurement range and load-bearing capacity. However, the elastic beams in this design experience complex stress patterns, and their strain response is easily affected by multi-dimensional load coupling, resulting in significant crosstalk interference between measurement channels. Furthermore, under miniaturization design conditions, it is impossible to simultaneously meet the performance requirements of high sensitivity and low mechanical hysteresis.

[0006] In addition, existing strain gauge arrangement schemes for six-dimensional force sensors generally have common defects: most adopt uniform or empirical arrangement methods, failing to accurately locate the strain concentration area of ​​each sensitive beam and optimize the strain gauge layout according to the load characteristics of different measurement dimensions, thus failing to fully amplify the target bending strain response and suppress non-target strain interference; the strain measurement of some structures is simultaneously affected by the coupling effect of bending strain and axial strain, and non-target strain cannot be effectively canceled, resulting in inter-dimensional coupling error of 5% to 12% FS, which seriously restricts the measurement accuracy and long-term stability of the sensor.

[0007] Therefore, there is an urgent need in this field to develop a six-dimensional force sensor elastomer structure with a simple and compact structure, excellent strain concentration effect, and bending strain as the core measurement sensitive source, while effectively reducing interdimensional coupling error and mechanical hysteresis, as well as a matching strain gauge arrangement method, to meet the core application requirements of high precision, high stability and miniaturized integration in six-dimensional force / torque measurement scenarios. Summary of the Invention

[0008] The purpose of this invention is to overcome the aforementioned defects in the prior art and provide a strain gauge arrangement method for a strain-type six-dimensional force sensor with a four-L-shaped elastic beam structure. This invention specifically addresses the core problems in the prior art, such as complex elastic body structures, dispersed strain distribution leading to insufficient measurement sensitivity, severe inter-dimensional coupling requiring complex nonlinear decoupling algorithms, and large mechanical hysteresis in split structures. By using an integrated elastic body structure design, the power flow transmission path is simplified, and mechanical hysteresis is reduced. The directional bending deformation characteristics of the L-shaped elastic beam are used to construct a stable strain concentration area, improving measurement sensitivity. Targeted optimization of the strain gauge layout suppresses interference from non-target dimension loads, reducing inter-dimensional coupling errors from the structural source and simplifying the implementation of subsequent decoupling algorithms. Ultimately, this achieves high-precision and high-stability measurement of six-dimensional force / torque.

[0009] I. Technical Solution

[0010] To achieve the above-mentioned objectives, the core technical solution of this invention consists of two parts: an elastomer structure product solution and a matching strain gauge arrangement method solution. The core logic is as follows: First aspect: Elastic structure of strain gauge six-dimensional force sensor

[0011] The elastomer of this invention adopts an integrated design, with the core including an outer ring arranged coaxially, a central loading platform, and four L-shaped elastic beams connecting the two; the overall structure has no splicing, welding or other split connection interfaces, eliminating assembly errors from the source and reducing mechanical hysteresis and nonlinear errors caused by stress deformation.

[0012] Four L-shaped elastic beams are evenly distributed along the circumference of the outer ring, forming a symmetrical force-sensitive structure. Each L-shaped elastic beam includes a first beam segment and a second beam segment that are perpendicular to each other. The first beam segment is fixed to the inner wall of the outer ring, and the second beam segment is fixed to the outer wall of the central loading platform. This allows the beam to produce directional deformation, mainly bending deformation, when it is loaded, forming a stable and concentrated strain-sensitive zone on the surface of the beam, thus solving the problems of strain dispersion and insufficient sensitivity in existing cross beam structures.

[0013] The outer ring and the central loading platform are respectively provided with threaded holes for installation and fixing, so as to realize the boundary constraint of the elastic body and the stable input of external load. Twelve strain gauges with the same parameters are attached to the strain concentration area of ​​each L-shaped elastic beam. The strain gauges are connected to the Wheatstone bridge measurement circuit through wires to realize the measurement of six-dimensional force / torque.

[0014] To further improve measurement accuracy and suppress interdimensional coupling, 12 strain gauges are arranged in pairs with non-uniform optimization based on strain concentration areas located by finite element simulation. This ensures that each measurement channel only generates a strong response to the force / moment components of the target dimension, while significantly suppressing the response to loads in non-target dimensions. Simultaneously, a Wheatstone bridge configuration with two working gauges on a half-bridge allows for differential extraction of the target bending strain signal, naturally canceling interference from non-target strains such as axial tension and overall deformation. This significantly reduces the nonlinearity of interdimensional coupling and simplifies the implementation of subsequent decoupling algorithms. The paired strain gauges, combined with the half-bridge dual-working-gauge structure, create differential output: the target bending strain causes the two strain gauges to produce opposite resistance changes (one tensile, one compressive), doubling the bridge output signal and amplifying the target response; while non-target strains such as axial tension and overall deformation cause the two strain gauges to produce resistance changes in the same direction, canceling each other out in the bridge. This achieves the effect of enhancing the target strain response and suppressing non-target interference.

[0015] In a preferred embodiment, four L-shaped elastic beams are distributed at 90° intervals along the outer circumference of the ring, ensuring that the elastic body has symmetrical mechanical response characteristics when subjected to force in all directions. The L-shaped elastic beams are made of metallic elastic materials with high elastic modulus and low hysteresis characteristics, further improving the long-term working stability of the sensor. The symmetrical structure with 90° intervals ensures that the deformation law of the beam is completely symmetrical when the elastic body is loaded in all directions, avoiding additional strain introduced by structural asymmetry and suppressing load crosstalk in non-target dimensions from the structural source.

[0016] The second aspect: the strain gauge arrangement method of a strain gauge-type six-dimensional force sensor.

[0017] This invention also provides a strain gauge arrangement method for the above-mentioned elastic body structure. The core is to reduce interdimensional coupling from the structural source by locating the strain-sensitive area in advance through simulation and optimizing the strain gauge layout accordingly. The core process includes: first, locking the bending strain concentration area of ​​each L-shaped elastic beam through finite element simulation; then, oriented and pairing strain gauges according to the measurement requirements of each dimension; then, building a measurement bridge that corresponds one-to-one with the six-dimensional components; and finally, verifying the arrangement effect and implementing the measurement.

[0018] As a preferred embodiment, the elastomer is manufactured using an integral processing technology with processing accuracy controlled within ±0.02 mm, ensuring the dimensional consistency and mechanical response symmetry of each L-shaped elastic beam; by adjusting the elastomer material and structural dimensions, it can flexibly adapt to application scenarios with different range and stiffness requirements.

[0019] II. Beneficial Effects

[0020] Compared with the prior art, the present invention has the following significant beneficial effects, and each effect corresponds one-to-one with the technical problem to be solved by the present invention: 1. Addressing the shortcomings of existing technologies such as complex elastomer structures and large mechanical hysteresis: This invention adopts an integrated elastomer structure constructed from four sets of L-shaped elastic beams. The overall structure is simple and compact, with fewer parts, a clear force transmission path, and no separate connection interfaces. This eliminates the performance impact caused by assembly errors, effectively improves the overall structural stiffness, reduces mechanical hysteresis and nonlinear errors caused by stress deformation, and significantly improves the dynamic response performance and long-term working stability of the sensor.

[0021] 2. Addressing the shortcomings of existing technologies such as dispersed strain distribution and insufficient measurement sensitivity: This invention utilizes the vertical bending structure design of an L-shaped elastic beam to induce directional deformation, primarily bending deformation, in the beam under load. This creates a stable and concentrated strain-sensitive zone within the beam. Combined with strain gauges precisely positioned in the region of maximum bending strain using finite element simulation, the response amplitude of the target bending strain signal is significantly enhanced, effectively improving the sensor's measurement sensitivity and resolving the inherent defects of dispersed strain and insufficient sensitivity in existing cross-beam structures.

[0022] 3. Addressing the shortcomings of existing technologies, such as severe interdimensional coupling and reliance on complex nonlinear decoupling algorithms: This invention employs a symmetrical beam structure with 90° equal intervals, combined with a non-uniform optimized layout of 12 strain gauges. This ensures that each measurement channel generates a strong response only to the target force or moment component, significantly suppressing the response to non-target dimensional loads and greatly reducing interdimensional coupling errors. Simultaneously, by using paired strain gauges in conjunction with a conventional Wheatstone bridge configuration with dual working gauges on a half-bridge, the target strain signal can be differentially extracted, naturally canceling non-target strain interference. This significantly reduces the nonlinearity of interdimensional coupling, effectively simplifying the implementation difficulty of subsequent data-driven nonlinear decoupling and improving the accuracy and efficiency of the solution.

[0023] 4. Addressing the shortcomings of poor measurement consistency and weak adaptability in existing technologies: The elastomer of this invention adopts an integrated processing technology, which can ensure the dimensional consistency and mechanical response symmetry of each L-shaped elastic beam, thereby improving the batch consistency and measurement repeatability of the sensor. At the same time, by adjusting the material and structural dimensions of the elastomer, it can flexibly adapt to application scenarios with different range and stiffness requirements. While achieving miniaturized integrated design, it also takes into account the comprehensive performance of high sensitivity, large range, low coupling, and low hysteresis. It can be widely used in various six-dimensional force / torque high-precision measurement scenarios such as precision assembly of industrial robots, aerospace measurement and control, and minimally invasive medical surgery. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the elastic body of the four L-shaped elastic beam strain-type six-dimensional force sensor provided in an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram showing the arrangement of strain gauges on an elastic body according to an embodiment of the present invention;

[0026] Figure 3 This is a circuit diagram of a half-bridge dual-chip Wheatstone bridge used in an embodiment of the present invention.

[0027] The component names marked in the above figures are as follows: 1-Outer ring, 2-Central loading platform, 3-L-shaped elastic beam, 31-First beam segment, 32-Second beam segment, 4-Strain gauge; B i Let U be the i-th measurement bridge (i=1,2,…,6), R1 and R2 are strain gauges, R3 and R4 are compensation resistors, U0 is the bridge output voltage, and U1 is the bridge excitation voltage. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0029] like Figure 1 As shown, the strain-type six-dimensional force sensor elastomer structure provided in this embodiment is an integrally machined elastic sensitive structure. The core includes an outer ring 1, a central loading platform 2, and four L-shaped elastic beams 3 connecting the outer ring 1 and the central loading platform 2.

[0030] like Figure 1 As shown, the spatial rectangular coordinate system defined in this embodiment is as follows: the center of the central loading platform 2 is the origin of the coordinate system, the line connecting the centers of two opposing L-shaped elastic beams 3 on the horizontal plane is the X-axis, the line connecting the centers of another set of opposing L-shaped elastic beams 3 perpendicular to the X-axis is the Y-axis, and the direction perpendicular to the end face of the elastic body is the Z-axis. The X-axis, Y-axis, and Z-axis satisfy the right-hand rule. The front and rear surfaces, left and right surfaces, upper and lower surfaces of the beam, as well as the positive and negative directions of X / Y / Z, are all defined based on this coordinate system.

[0031] The central loading platform 2 is coaxially arranged inside the outer ring 1. Four L-shaped elastic beams 3 are evenly distributed at 90° intervals along the circumference of the outer ring 1, and the included angle between the centers of adjacent L-shaped elastic beams 3 is 90°, ensuring that the elastic body has symmetrical mechanical response characteristics when loaded in all directions. Each L-shaped elastic beam 3 includes an integrally formed first beam segment 31 and a second beam segment 32 that are perpendicular to each other. The free end of the first beam segment 31 is fixed to the inner wall of the outer ring 1, and the free end of the second beam segment 32 is fixed to the outer wall of the central loading platform 2, forming a vertically bent L-shaped structure. This allows the L-shaped elastic beam 3 to produce directional deformation mainly in the form of bending deformation when loaded, forming a stable and concentrated strain-sensitive area on the surface of the beam.

[0032] In this embodiment, the elastomer is made of 40CrNiMoA high-strength alloy steel and the processing technology is a combination of wire cutting and CNC milling. The processing accuracy is controlled within ±0.02 mm, eliminating the interface between the parts and ensuring the dimensional consistency and mechanical response symmetry of each L-shaped elastic beam 3, reducing the mechanical hysteresis and nonlinear error caused by stress deformation. In other optional embodiments, other metal elastic materials such as aluminum alloy and stainless steel can be selected according to the range and stiffness requirements.

[0033] In this embodiment, the cross-section of the L-shaped elastic beam 3 is rectangular, and the specific dimensional parameters are as follows: the length of the first beam segment 31 is 25mm, the width is 6mm, and the thickness is 6mm; the length of the second beam segment 32 is 18mm, the width is 6mm, and the thickness is 6mm; the inner diameter of the outer ring 1 is 55mm, the outer diameter is 72mm, and the thickness is 12mm; the central loading platform 2 is a disc-shaped structure with a diameter of 40mm and a thickness of 12mm, which matches the dimensions of the outer ring 1 and the L-shaped elastic beam 3 to ensure that the structure is subjected to stress in a coordinated manner.

[0034] In other alternative embodiments, the structural dimensions can be adjusted within the following ranges according to the actual range and stiffness requirements: beam segment width 4~8 mm, thickness 4~8 mm; first beam segment 31 length 20~30 mm, second beam segment 32 length 15~21 mm, the length ratio of the two beam segments is 0.5:1~1.5:1; outer ring 1 inner diameter 52~58 mm, outer diameter 69~75 mm, thickness 9~15 mm; central loading platform 2 diameter 37~43 mm, thickness 10~15 mm.

[0035] The central loading platform 2 has four through-holes evenly distributed around the circumference, with M4 thread specifications. The axis of the threaded holes is parallel to the axial direction of the central loading platform 2. These holes are used to fix the platform to the sensor cover, allowing for the input of external multi-directional forces and torques through the cover. The outer ring 1 has eight non-through-holes evenly distributed around the circumference, with M4 thread specifications. The axis of the threaded holes is perpendicular to the radial direction of the outer ring 1. These holes are used to fix the platform to the sensor housing and the lower cover, enabling the installation and fixation of the elastic body and complete boundary constraints.

[0036] Under the action of external force or moment load, the L-shaped elastic beam 3 mainly undergoes bending deformation, which can form an obvious strain concentration area on the surface of the beam, providing a precise positioning basis for the arrangement of strain gauges 4.

[0037] like Figure 2 As shown, in this embodiment, a total of 12 strain gauges 4, numbered S1 to S12, are attached to the surface of each L-shaped elastic beam 3. All strain gauges 4 have identical parameters except for their numbers. The specific parameters are: nominal resistance 120 Ω, strain sensitivity coefficient K0 = 2.0 ± 0.5%, sensitive grid length 2 mm, and each strain gauge is a quarter-arm unit of a Wheatstone bridge with a base size of 6 mm × 4 mm, which is adapted to the strain range of the beam surface.

[0038] The placement of the 12 strain gauges 4 is based on the non-uniform arrangement of the bending strain concentration area determined by finite element analysis. The number and position of strain gauges on different beams are optimized according to the sensitivity requirements of different measurement directions. In this embodiment, the method for determining the strain concentration area is as follows: a simulation model of the elastic body is established using ANSYS finite element simulation software, a fixed constraint is applied to the mounting surface of the outer ring 1, standard forces and moment loads in different directions are applied to the central loading platform 2, and the surface strain cloud map of each L-shaped elastic beam 3 is extracted. The area with the largest absolute value of bending strain is taken as the target strain concentration area, providing a design basis for the accurate placement of strain gauges.

[0039] The specific mounting locations of the 12 strain gauges are as follows: Strain gauges S1 and S2 are attached to the front and rear surfaces of the first beam segment 31 of the L-shaped elastic beam 3 in the negative X direction, near the area of ​​the second beam segment 32. Strain gauges S3 and S4 are attached to the front and rear surfaces of the first beam segment 31 of the L-shaped elastic beam 3 in the negative Y direction, near the area of ​​the second beam segment 32. Strain gauges S5 and S6 are attached to the front and rear surfaces of the first beam segment 31 of the L-shaped elastic beam 3 in the positive X direction, near the area of ​​the second beam segment 32. Strain gauges S7 and S8 are attached to the left and right surfaces of the first beam segment 31 of the L-shaped elastic beam 3 in the positive X direction, near the central loading platform 2. Strain gauges S9 and S10 are attached to the front and rear surfaces of the first beam segment 31 of the L-shaped elastic beam 3 in the positive Y direction, near the area of ​​the second beam segment 32. Strain gauges S11 and S12 are attached to the upper and lower surfaces of the first beam segment 31 of the L-shaped elastic beam 3 in the positive Y direction, near the area of ​​the outer ring 1.

[0040] All strain gauges 4 are attached in pairs to the region of maximum bending strain of the corresponding L-shaped elastic beam 3, and are arranged along the length of the beam or the side wall direction to ensure that the sensitive grid direction of the strain gauge is consistent with the target strain direction, thereby maximizing the response amplitude to the target bending strain and suppressing interference from non-target strains.

[0041] like Figure 3 As shown, in this embodiment, 12 strain gauges 4 are connected to the Wheatstone bridge measurement circuit through shielded wires to form 6 independent measurement bridges. Each measurement bridge adopts a half-bridge dual-working-gauge structure. Each bridge circuit Bᵢ (i=1,2,…,6) consists of two strain gauges forming a working arm (R1, R2). Both strain gauges are arranged in the bending strain concentration area of ​​the corresponding L-shaped elastic beam 3. The other two arms of the bridge circuit (R3, R4) are 120 Ω compensation resistors that are precisely matched with the nominal resistance of the strain gauges and are used for temperature compensation and bridge circuit output stabilization.

[0042] In this embodiment, the bridge excitation voltage U1 is 2 V DC, and the voltage signal amplitude output by the output terminal Uo is proportional to the resistance change of the strain gauge. The two strain gauges arranged in pairs are mounted along the relative strain direction, share the bridge lead and maintain the same polarity to realize differential signal output. This can naturally cancel the resistance change caused by non-target strains such as axial tension and overall deformation, and reduce the interference of non-bending strain on the measurement results.

[0043] The six sets of measuring bridges correspond one-to-one with the six-dimensional force / torque components, and the specific correspondence is as follows: Bridge circuit B1 consists of strain gauges S3 and S4, used to measure the force component Fx in the X direction; Bridge circuit B2 consists of strain gauges S5 and S6, used to measure the force component Fᵧ in the Y direction; Bridge circuit B3 consists of strain gauges S11 and S12, used to measure the force component F in the Z direction. z ; Bridge circuit B4 consists of strain gauges S1 and S2, and is used to measure the torque component Mx around the X-axis; Bridge circuit B5 consists of strain gauges S9 and S10, used to measure the torque component Mᵧ about the Y-axis; Bridge circuit B6 consists of strain gauges S7 and S8, used to measure the torque component M about the Z-axis. z .

[0044] The strain gauge arrangement method corresponding to this embodiment is implemented according to the following steps: (1) Steps for precise positioning of strain concentration area: Based on the integrated elastic body structure of this embodiment, a finite element simulation model is established, loads and boundary conditions are applied, and the full-field strain distribution law of the elastic body under the action of force and moment load in different directions is simulated. The area with the maximum bending strain and the optimal strain gradient during the bending deformation of each L-shaped elastic beam 3 is precisely locked as the target strain concentration area for strain gauge mounting. (2) Strain gauge orientation mounting step: According to the strain concentration area determined in step (1), 12 strain gauges 4 with the same parameters are mounted at the corresponding positions of each L-shaped elastic beam 3 according to the mounting positions mentioned above in this embodiment. All strain gauges are mounted in pairs in the area of ​​maximum bending strain and are mounted along the beam length direction or side wall direction to ensure that the strain gauge sensitive grid direction is consistent with the target strain direction. (3) Measurement bridge matching and construction steps: Connect the installed strain gauge 4 to the Wheatstone bridge measurement circuit through shielded wires. According to the half-bridge dual working plate structure described above in this embodiment, build 6 sets of measurement bridges that correspond one-to-one with the six-dimensional force / torque components to complete the arrangement of strain gauges and bridge circuit debugging. (4) Verification steps for the arrangement effect: Calibrate the sensor after the patch and bridge circuit are completed, apply standard force / torque load, verify the sensitivity, linearity and interdimensional coupling characteristics of each measurement channel, and complete the arrangement verification of the strain gauge. In this embodiment, the sensor calibration can be performed using a standard calibration device for a six-dimensional force sensor, which is completed by applying standard loads step by step. The calibration process complies with the national industry standard requirements for resistance strain gauge six-dimensional force sensors.

[0045] The principle of the six-dimensional force / torque measurement in this embodiment is as follows: When an external force or torque is applied to the central loading platform 2 through the sensor cover, the elastic body produces a small elastic deformation corresponding to the load, and the strain concentration area of ​​each L-shaped elastic beam 3 produces a corresponding strain change, which drives the strain gauge 4 attached to the area to produce a corresponding resistance value change; the resistance change is converted into a voltage signal with a corresponding amplitude through a Wheatstone bridge, and the output voltage amplitude is proportional to the target bending strain.

[0046] By leveraging the symmetrical structure of the elastic body and the optimized arrangement of strain gauges, the influence of non-target dimension loads on the output of the corresponding bridge circuits is significantly suppressed, greatly reducing the nonlinearity of interdimensional coupling and providing a high-quality raw signal foundation for subsequent high-precision data-driven nonlinear decoupling. After acquisition, the voltage signals output by each bridge circuit are calibrated and linearly mapped to establish a correspondence with the external six-dimensional force / torque components. These are then processed using a data-driven nonlinear decoupling algorithm to ultimately obtain Fx, Fᵧ, and F... z Force components in three orthogonal directions, and Mx, Mᵧ, M z Torque components of three orthogonal axes.

[0047] Through the above structural design and strain gauge arrangement, the elastic body in this embodiment can produce directional local bending deformation under the action of multi-directional forces and moments. The strain gauges have a clear strain response to the target load, and the bridge circuit output is stable. It can achieve high sensitivity, high repeatability, and low coupling measurement of six-dimensional force / moment. Relying on the symmetrical structure of the elastic body and the optimized layout of the strain gauges, it can effectively suppress load crosstalk in non-target dimensions, reduce the nonlinearity of inter-dimensional coupling, simplify the implementation difficulty of subsequent nonlinear decoupling algorithms, and meet the application requirements of high-precision six-dimensional force measurement in industrial scenarios.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A strain gauge six-dimensional force sensor elastomer structure, characterized in that: It includes an outer ring (1), a central loading platform (2), and an elastic beam connecting the outer ring (1) and the central loading platform (2). The central loading platform (2) is coaxially disposed inside the outer ring (1). The elastic beam is evenly distributed along the circumference of the outer ring (1) between the outer ring (1) and the central loading platform (2). Its characteristic is that: The elastic beam consists of four L-shaped elastic beams (3). Each L-shaped elastic beam (3) includes a first beam segment (31) and a second beam segment (32) that are perpendicular to each other. The free end of the first beam segment (31) is fixed to the inner wall of the outer ring (1), and the free end of the second beam segment (32) is fixed to the outer wall of the central loading platform (2). The outer ring (1), the central loading platform (2), and the four L-shaped elastic beams (3) are integrally formed to constitute an integral elastic body structure.

2. The strain-type six-dimensional force sensor elastomer structure according to claim 1, characterized in that: The four L-shaped elastic beams (3) are distributed at equal intervals of 90° along the circumference of the outer ring (1), so that the elastic body has symmetrical mechanical response characteristics when subjected to force in all directions; The first beam segment (31) and the second beam segment (32) are integrally formed and form a vertical bending structure, so that the L-shaped elastic beam (3) produces directional deformation mainly of bending deformation when it is loaded; The L-shaped elastic beam (3) is made of a metallic elastic material, which is selected from aluminum alloy, stainless steel or alloy steel, wherein the alloy steel is preferably 40CrNiMoA high-strength alloy steel.

3. The strain-type six-dimensional force sensor elastomer structure according to claim 1 or 2, characterized in that: The outer ring (1) has 6 to 10 non-through threaded holes. The threaded holes are evenly distributed along the circumference of the outer ring (1), and the axis of each threaded hole is perpendicular to the radial direction of the outer ring (1). The threaded holes are used to fix the sensor housing and the lower cover to realize the installation, fixation and boundary constraint of the elastic body. The central loading platform (2) has 4 to 8 through-holes. The threaded holes are evenly distributed around the circumference of the central loading platform (2), and the axis of each threaded hole is parallel to the axis of the central loading platform (2). The threaded holes are used to fix the sensor cover to the sensor cover so as to realize the load input of multi-directional force and torque through the cover.

4. A strain gauge six-dimensional force sensor, comprising an elastic body structure, strain gauges, and a Wheatstone bridge measurement circuit, characterized in that: The elastic body structure is the strain-type six-dimensional force sensor elastic body structure as described in any one of claims 1 to 3; Define a spatial rectangular coordinate system: with the center of the central loading platform (2) as the origin, the line connecting the centers of two opposite L-shaped elastic beams (3) in the radial plane of the elastic body as the X-axis, the line connecting the centers of another set of opposite L-shaped elastic beams (3) perpendicular to the X-axis in the radial plane of the elastic body as the Y-axis, and the direction perpendicular to the end face of the elastic body as the Z-axis. The X-axis, Y-axis, and Z-axis satisfy the right-hand rule; the front and rear surfaces of the beam are perpendicular to the Y-axis, the left and right surfaces are perpendicular to the X-axis, and the upper and lower surfaces are perpendicular to the Z-axis. There are 12 strain gauges, numbered S1 to S12. All strain gauges have the same parameters except for their numbers, namely, the initial resistance and strain sensitivity coefficient K0 are the same. The 12 strain gauges (4) are arranged in the area where the maximum bending strain occurs when the corresponding L-shaped elastic beam (3) is subjected to force. Each strain gauge (4) is electrically connected to the Wheatstone bridge measurement circuit through wires to realize six-dimensional measurement of the force components along the three orthogonal directions and the torque components around the three orthogonal axes. The specific mounting positions of each strain gauge are as follows: Strain gauges S1 and S2 are attached to the front and rear surfaces of the first beam segment (31) of the L-shaped elastic beam (3) located in the negative X-axis direction, near the second beam segment (32); Strain gauges S3 and S4 are attached to the front and rear surfaces of the first beam segment (31) of the L-shaped elastic beam (3) located in the negative Y-axis direction, near the second beam segment (32); Strain gauges S5 and S6 are attached to the front and rear surfaces of the first beam segment (31) of the L-shaped elastic beam (3) located in the positive direction of the X-axis, near the second beam segment (32); Strain gauges S7 and S8 are attached to the left and right surfaces of the first beam segment (31) of the L-shaped elastic beam (3) located in the positive direction of the X-axis, near the central loading platform (2). Strain gauges S9 and S10 are attached to the front and rear surfaces of the first beam segment (31) of the L-shaped elastic beam (3) located in the positive direction of the Y-axis, near the second beam segment (32); Strain gauges S11 and S12 are attached to the upper and lower surfaces of the first beam segment (31) of the L-shaped elastic beam (3) located in the positive direction of the Y-axis, near the outer ring (1).

5. The strain gauge six-dimensional force sensor according to claim 4, characterized in that: All strain gauges are attached in pairs to the region of maximum bending strain of the corresponding L-shaped elastic beam (3) and arranged along the length of the beam or the sidewall direction to enhance the response to the target bending strain and suppress the interference of non-target strain. Each strain gauge (4) is connected to the Wheatstone bridge measurement circuit through wires to form 6 sets of measurement bridges. Each measurement bridge adopts a half-bridge double working plate structure to extract the strain signal generated by the bending deformation of the L-shaped elastic beam (3) and reduce the influence of non-bending strain on the measurement results. The 6 sets of measurement bridges correspond one-to-one with the three-dimensional orthogonal force components and the three-dimensional orthogonal moment components, and are used for independent measurement of the corresponding single-dimensional force or moment components.

6. A method for arranging strain gauges in a strain-type six-dimensional force sensor, characterized in that: The strain-type six-dimensional force sensor is the strain-type six-dimensional force sensor according to any one of claims 4-5, and the method includes the following steps: (1) Precise positioning steps of strain concentration area: Based on the integrated elastomer structure described in claim 1, the full-field strain distribution law of the elastomer under different directional force and moment load is simulated by finite element analysis, and the area with the maximum bending strain and optimal strain gradient during the bending deformation of each L-shaped elastic beam (3) is determined as the target strain concentration area for strain gauge mounting. (2) Strain gauge orientation mounting step: According to the strain concentration area determined in step (1), 12 strain gauges (4) with the same parameters are mounted at the corresponding positions of each L-shaped elastic beam (3) according to the mounting position described in claim 4. All strain gauges are mounted in pairs in the area of ​​maximum bending strain and are mounted along the beam length direction or side wall direction to ensure that the strain gauge sensitive grid direction is consistent with the target strain direction. (3) Measurement bridge matching and construction steps: Connect the mounted strain gauge (4) to the Wheatstone bridge measurement circuit through wires, and build 6 sets of measurement bridges corresponding to the six-dimensional force / torque components according to the half-bridge dual working plate structure described in claim 5, and complete the entire process of strain gauge arrangement. (4) Verification steps for the arrangement effect: Calibrate the sensor after the patch and bridge circuit are completed, apply standard force / torque load, verify the sensitivity, linearity and interdimensional coupling characteristics of each measurement channel, and complete the arrangement verification of strain gauges.

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