Six-dimensional force elastomer with structural decoupling capability and force sensor

Abstract

The invention provides a six-dimensional force elastomer with structural decoupling capability, and relates to a force sensor, the six-dimensional force elastomer comprises an inner mounting block, an outer mounting ring and a composite elastic beam connecting the inner mounting block and the outer mounting ring which are coaxially arranged, the structural shape of the composite elastic beam, the arrangement positions of strain gauges and the connection relation of the strain gauges in a full bridge are matched, and the strain gauges of FX and FY are arranged on the inner mounting block and the outer mounting ring. When a single load in the FX direction or the FY direction is received, a high strain area above the mean value of the surface stress of the composite elastic beam enables the strain distribution of a target channel strain gauge to enable the full-bridge output to meet the formula: Vout is approximate to (Vin * GF / 4) * (epsilon 2 + epsilon 3-epsilon 1-epsilon 4) when the elastic body bears a single load in the target direction, and the absolute value of the combination item is sufficiently large. The strain distribution of a non-target channel strain gauge enables the full-bridge output to be fully minimized due to low strain isolation or a bridge circuit self-balancing mechanism; hardware-level high-precision decoupling measurement is realized, inter-dimensional coupling interference is effectively suppressed, and coupling errors are reduced.

Description

Technical Field

[0001] This invention relates to the field of force sensor technology, and in particular to a six-dimensional force elastomer and force sensor with structural decoupling capability. Background Technology

[0002] The core performance indicators of a six-dimensional force sensor are accuracy and inter-dimensional decoupling. Traditional elastic bodies (such as crossbeams and Stewart structures) are limited by mechanical coupling, and when subjected to force in a single direction, crosstalk signals are generated in multiple measurement channels. This coupling usually requires complex calibration matrices and software algorithms for compensation, which not only increases the complexity and cost of the system, but may also introduce problems such as temperature drift, nonlinearity, and long-term stability.

[0003] The applicant has discovered that the prior art suffers from at least the following technical problems: While prior art attempts to reduce coupling through structural optimization, it is difficult to achieve complete decoupling over a wide range. For example, some designs employ over-constrained structures or localized flexible hinges, but significant coupling errors still occur under high loads or combined forces. Furthermore, if the strain gauge mounting location and bridging method are not precisely matched to the structural strain field, signal crosstalk will be further exacerbated.

[0004] Therefore, there is an urgent need for a six-dimensional force-elastic body that can be collaboratively optimized throughout the entire process from mechanical strain generation to electrical signal conversion, so as to fundamentally achieve high-precision decoupling at the hardware level. Summary of the Invention

[0005] The purpose of this invention is to provide a six-dimensional force-elastic body and force sensor with structural decoupling capability, thereby solving the technical problems of severe coupling and large measurement errors in existing six-dimensional force sensors. The various technical effects of the preferred solutions among the many technical solutions provided by this invention are detailed below.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The six-dimensional force-elastic body with structural decoupling capability provided by this invention includes an inner mounting block, an outer mounting ring, and multiple sets of composite elastic beams connecting the two, wherein: The composite elastic beam is provided with at least 6 groups of 24 strain gauges. The six groups of strain gauges are used to measure the force in the three directions FX, FY, and FZ and the torque in the three directions MX, MY, and MZ, respectively. Each group of strain gauges is electrically connected according to the corresponding Wheatstone full-bridge circuit topology to form six independent measuring bridges. The tensile and compressive polarities of the strain gauges in each group are defined according to their strain direction under the corresponding positive load and correspond to the bridge arm positions in the circuit topology. The structural shape of the composite elastic beam, the arrangement of the strain gauges, and their connection relationships in the entire bridge are coordinated to ensure that when the elastic body is subjected to a load in a single target direction, the strain distribution of the target channel strain gauges causes the entire bridge output to satisfy the formula: Vout ≈ (Vin×GF / 4)×(ε2+ε3-ε1-ε4), and the absolute value of this combined term is sufficiently large; while the strain distribution of the non-target channel strain gauges causes the entire bridge output to be sufficiently minimized due to low strain isolation or the bridge self-balancing mechanism. Among them, the bridge self-balancing mechanism refers to the strain distribution of the non-target channel satisfying ε2+ε3≈ε1+ε4, which makes its output approach zero, thereby achieving a coupling error ≤5%; Where Vout represents the output voltage of the Wheatstone full-bridge circuit, Vin represents the excitation voltage of the Wheatstone full-bridge circuit, GF represents the sensitivity coefficient of the strain gauge, and ε1, ε2, ε3, and ε4 represent the strain values ​​generated by each group of four strain gauges under stress.

[0008] Preferably, the composite elastic beam comprises four vertically distributed elastic beams and eight buffer beams, wherein: The ends of the eight buffer beams are fixedly connected to the inner wall of the outer mounting ring, forming a regular octagonal frame; the opposite ends of the elastic beams are respectively fixedly connected to the inner mounting block and the corresponding ends of the buffer beams. Alternatively, four of the buffer beams are fixedly connected to form a regular quadrilateral frame, and the other four buffer beams are fixedly connected to the end corners of the regular quadrilateral frame and the end corners of the inner mounting block. The opposite ends of the elastic beam are respectively fixed to the outer mounting ring and the middle of the corresponding side of the regular quadrilateral frame. All elastic beams and the buffer beams are centrally symmetrical about the central axis of the elastic body, and are axially symmetrical about the central axis of the elastic body. The six sets of strain gauges are distributed at corresponding positions on the elastic beam and / or the buffer beam; Among them, the two tensile strain gauges of FX are arranged on two opposite buffer beams, and the two compressive strain gauges of FX are arranged on another set of two opposite buffer beams; The two tensile strain gauges of FY are disposed on two oppositely arranged buffer beams, and the two compressive strain gauges of FY are disposed on another set of two oppositely arranged buffer beams.

[0009] Preferably, the composite elastic beam comprises four vertically distributed elastic beams, wherein: The two ends of the elastic beam are fixedly connected to the inner mounting block and the outer mounting ring, respectively, and the six sets of strain gauges are distributed at the corresponding positions of the elastic beam. The elastic beam has a recessed portion to allow strain gauges FX and FY to be arranged in the high-strain region above the average stress value on the surface of the composite elastic beam.

[0010] Preferably, the recessed portion includes a groove, the grooves are symmetrically arranged on opposite sides of the same elastic beam, and strain gauges FX and FY are distributed on the side of the groove; Alternatively, the recess may include a through hole that extends through both opposite sides of the same elastic beam, with strain gauges FX and FY distributed on the sides of the through hole.

[0011] Preferably, each of the elastic beams is an independent beam structure, or each of the elastic beams includes two or more beam columns; When the elastic beam includes two or more beams, the two beams in the same group are arranged along the corresponding sidewall of the inner mounting block, and a gap hole is formed between them.

[0012] Preferably, under rated uniaxial load, when the output of any target measurement channel is 100%, the output of the other five non-target channels is less than 2% of their own full scale.

[0013] Preferably, the composite elastic beam has a precision-machined plane; the 24 strain gauges are symmetrically arranged on the same side or opposite sides of the plane of the composite elastic beam.

[0014] Preferably, the strain gauge is a metal foil strain gauge, a silicon strain gauge, or a thick film resistor, and each bridge satisfies the initial balance condition R1 / R2 = R3 / R4 when there is no load. R1, R2, R3, and R4 represent the resistance values ​​of the four arms of the Wheatstone full-bridge circuit, corresponding to the four strain gauges in each measurement dimension.

[0015] Preferably, the elastomer material is stainless steel, aluminum alloy, or titanium alloy.

[0016] The present invention also provides a six-dimensional force sensor, comprising the above-mentioned six-dimensional force elastomer with structural decoupling capability, a power supply module providing excitation voltage for each bridge, a signal conditioning circuit for amplifying the differential output signals of each bridge, and a housing.

[0017] The six-dimensional force-elastic body and force sensor with structural decoupling capability provided by this invention have the following advantages compared with the prior art: the combination of the composite elastic beam structure shape, strain gauge placement, and full-bridge circuit connection relationship realizes high-precision decoupling measurement at the hardware level. On the one hand, the strain gauges of FX and FY are precisely placed in the high-strain region on the surface of the composite elastic beam. Combined with the scientific configuration of the Wheatstone full-bridge circuit topology, the target channel reaches the theoretical maximum output sensitivity under a single load. On the other hand, through the dual mechanisms of low-strain isolation and bridge self-balancing (non-target channels satisfy ε1≈ε3 and ε2≈ε4), inter-dimensional coupling interference is effectively suppressed from the physical source, and the coupling error is controlled at an excellent level of ≤5% (significantly better than the 5%-20% of traditional designs). This greatly improves the measurement accuracy and reliability of the six-dimensional force sensor, providing a high-precision six-dimensional force sensor with compact structure, stable performance, and theoretical predictability for fields such as robotics and intelligent manufacturing. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 It is a strain analysis cloud diagram of a conventional six-dimensional force-elastic body in the existing technology; Figure 2 ab is a schematic diagram of the structure of a six-dimensional force-elastic body with structural decoupling capability in Embodiment 1; Figure 3 ac is a schematic diagram of the structure of a six-dimensional force-elastic body with structural decoupling capability, as shown in Embodiment 2. Figure 4 ac is a schematic diagram of the structure of a six-dimensional force-elastic body with structural decoupling capability in Embodiment 3; Figure 5 ac is a schematic diagram of the structure of a six-dimensional force-elastic body with structural decoupling capability in Embodiment 4; Figure 6 This is a schematic diagram of the structure of a six-dimensional force-elastic body with structural decoupling capability, as shown in Embodiment 5. Figure 7 It is a circuit diagram of a six-dimensional force-elastic body with structural decoupling capability; Figure 8 This is a strain analysis cloud diagram of Example 1 of a six-dimensional force-elastic body with structural decoupling capability; Figure 9 This is a strain analysis cloud diagram of Example 2 of a six-dimensional force-elastic body with structural decoupling capability; Figure 10 This is a strain analysis cloud diagram of Example 3 of a six-dimensional force-elastic body with structural decoupling capability; Figure 11 This is a strain analysis cloud diagram of Example 4 of a six-dimensional force-elastic body with structural decoupling capability; Figure 12 This is a strain analysis cloud diagram of Example 5 of a six-dimensional force-elastic body with structural decoupling capability; Figure 13 This is a strain analysis cloud diagram of another deformable structure in Example 5 of a six-dimensional force-elastic body with structural decoupling capability; Figure 14 This is a strain analysis cloud diagram of another deformable structure in Example 1 of a six-dimensional force-elastic body with structural decoupling capability; In the figure: 1. Inner mounting block; 2. Outer mounting ring; 3. Composite elastic beam; 31. Elastic beam; 311. Beam-column; 32. Buffer beam; 41. Groove; 42. Through hole; 43. Spacing hole. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] In the description of this invention, it should be understood that the terms "center," "length," "width," "height," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and "side," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0022] In existing technologies, the elastic body (such as a crossbeam structure) of force sensors is constrained by mechanical coupling. When a force is applied in a single direction, crosstalk signals are generated in multiple measurement channels. This coupling usually requires complex calibration matrices and software algorithms for compensation, which not only increases the system complexity and cost, but may also introduce problems such as temperature drift, nonlinearity, and long-term stability.

[0023] In the field of six-dimensional force sensors, coupling refers to the phenomenon where non-target measurement channels also generate output signals when the sensor is subjected to a force or torque (target load) in only a specific direction. Ideally, when only an X-axis force (FX) is applied, only the FX measurement channel should have an output, while the FY, FZ, MX, MY, and MZ channels should output zero signals. However, in practical sensors, when a 100% FX load is applied, other channels may generate 5%-20% of the output signal. This output from non-target channels is called coupling error, usually expressed as a percentage.

[0024] See Figure 1 As shown, Figure 1 This is a strain analysis cloud diagram of a conventional six-dimensional force elastomer in the prior art. The diagram shows the structure of the six-dimensional force elastomer and the arrangement of the 24 strain gauges. It can be seen from the diagram that when measuring the force in the FX direction, the maximum stress is not concentrated at the FX measurement channel, so the measurement error is relatively serious.

[0025] Coupling is essentially a manifestation of the inability of a mechanical structure to completely isolate mechanical responses in different directions, reflecting the decoupling capability of a sensor in multidimensional force measurement. The lower the coupling degree, the better the sensor performance.

[0026] As shown in the table below, the coupling error of conventional six-dimensional force elastomers in the prior art was calculated. It can be seen that the coupling error of conventional six-dimensional force elastomers in the prior art is relatively high.

[0027] Table 1. Coupling error data of conventional six-dimensional force elastomers in the prior art.

[0028] To address the aforementioned problems, this invention provides a six-dimensional force-elastic body with structural decoupling capability, comprising an inner mounting block 1, an outer mounting ring 2, and multiple sets of composite elastic beams 3 connected coaxially. At least six sets of 24 strain gauges are mounted on the composite elastic beams 3. These six sets of strain gauges are used to measure forces in the FX, FY, and FZ directions and moments in the MX, MY, and MZ directions, respectively. Each set of strain gauges is electrically connected according to a corresponding Wheatstone full-bridge circuit topology, forming six independent measurement bridges. The tensile and compressive polarities of each inner strain gauge are defined according to its strain direction under the corresponding positive load and correspond to the bridge arm positions in the circuit topology. The structural shape of the composite elastic beam 3, the arrangement of the strain gauges, and their connection relationships within the full bridge are coordinated. Specifically, the strain gauges for FX and FY are arranged in high-strain regions above the average surface stress of the composite elastic beam 3 when subjected to a single load in the FX or FY direction. This ensures that when the elastic body is subjected to a load in a single target direction, the strain distribution of the strain gauges in the target channel causes the full-bridge output to satisfy the formula: Vout ≈ (Vin×GF / 4)×(ε2+ε3- ε1-ε4), and the absolute value of this combined term is sufficiently large, so that the strain distribution of the non-target channel strain gauges minimizes the full-bridge output due to low strain isolation or bridge self-balancing mechanism; where the bridge self-balancing mechanism means that the strain distribution of the non-target channel satisfies ε2+ε3≈ε1+ε4, making its output approach zero, thereby achieving coupling error ≤5%; where Vout represents the output voltage of the Wheatstone full-bridge circuit, Vin represents the excitation voltage of the Wheatstone full-bridge circuit, GF represents the sensitivity coefficient of the strain gauge, and ε1, ε2, ε3, ε4 represent the strain values ​​generated by each group of four strain gauges under stress.

[0029] The aforementioned 6 groups, comprising 24 strain gauges, are identical to those in the prior art. These 6 groups of strain gauges correspond to force / torque measurements in six dimensions, and the specific grouping is defined as follows: Group Z1: Corresponds to FX measurements, including strain gauges FXR1-, FXR2+, FXR3+, and FXR4-.

[0030] Group Z2: Corresponds to FY measurements, including strain gauges FYR1-, FYR2+, FYR3+, and FYR4-.

[0031] Group Z3: Corresponds to FZ measurements, including strain gauges FZR1-, FZR2+, FZR3+, and FZR4-.

[0032] Group Z4: Corresponds to MX measurements, including strain gauges MXR1-, MXR2+, MXR3+, and MXR4-.

[0033] Group Z5: Corresponding to the MY measurement, it includes strain gauges MYR1-, MYR2+, MYR3+, MYR4-.

[0034] Group Z6: Corresponding to the MZ measurement, it includes strain gauges MZR1-, MZR2+, MZR3+, MZR4-.

[0035] The 4 strain gauges within each group are connected to form an independent Wheatstone full-bridge circuit. See the circuit schematic diagram in Figure 7 as shown.

[0036] Among them, for the strain gauges of FX, the symmetry relationship between the tensile group (FXR3+, FXR2+) and the compressive group (FXR1-, FXR4-) needs to satisfy: the positions of FXR3+ and FXR2+ are symmetric about the X-axis of the force elastic body, and the positions of FXR1- and FXR4- are symmetric about the X-axis; the same applies to the strain gauges of other groups.

[0037] The 24 strain gauges form six independent measurement channels. The specific grouping, bridge arm definition and polarity are (taking Group Z1 as an example): Group Z1 (measuring Fx): Bridge arm R1 corresponds to strain gauge FXR1-, bridge arm R2 corresponds to FXR2+, bridge arm R3 corresponds to FXR3+, and bridge arm R4 corresponds to FXR4-. The "+" and "-" polarity markings are defined based on their strain directions under the corresponding positive load.

[0038] The principle of the present invention is: The topological shape of the composite elastic beam 3 is optimized by finite element, so that the strain field distribution generated under a specific direction load is precisely matched with the pasting positions of the corresponding group of strain gauges and their specific full-bridge connection methods in the figure. This matching ensures that: when the target direction load is applied, the full-bridge output of the corresponding strain gauge group is maximized; when the non-target direction load is applied, the full-bridge outputs of other strain gauge groups are minimized through the low-strain isolation or bridge circuit self-balancing mechanism.

[0039] The decoupling characteristic of the present invention is realized based on the exact formula of the Wheatstone full-bridge output voltage and its linearization approximation. For a full-bridge composed of resistors R1, R2, R3, and R4, its output voltage Vout is: Vout = Vin×(R2R3 - R1R4) / [(R1 + R3)(R2 + R4)] —— (Formula A) Initially, by adjusting the resistance to satisfy R1 / R2 = R3 / R4, Vout = 0 is achieved. When the strain causes a small resistance change ΔRi (ΔRi << R0), assuming the initial resistance R0 = R1 = R2 = R3 = R4, substituting into Formula A and ignoring the higher-order small quantities, the linearized formula is obtained: Vout ≈ (Vin / 4)×(ΔR2 / R0 + ΔR3 / R0 - ΔR1 / R0 - ΔR4 / R0) Introducing the strain gauge sensitivity coefficient GF (ΔRi / R0=GF×εi), we have: Vout≈(Vin×GF / 4)×(ε2+ε3-ε1-ε4)——(Formula B, the core formula for decoupling) The decoupling design of this invention is achieved by controlling the strain distribution (ε1, ε2, ε3, ε4) and using a bridging method in the matching diagram: Main response maximization mechanism: For the target measurement group, the strain gauges are designed to meet the ideal distribution under the target load, where adjacent bridge arms have the same strain sign and relative bridge arms have different strain signs. Taking the Z1 bridge (measuring +Fx) in the figure as an example, the desired strain distribution is: ε1=-ε, ε2=+ε, ε3=+ε, ε4=-ε (i.e., R1 and R4 are under compression, and R2 and R3 are under tension); substituting into formula B, we get: Vout_target≈(Vin×GF / 4)×[(+ε)+(+ε)-(-ε)-(-ε)]=Vin×GF×ε, at which point the output reaches the theoretical maximum value and the sensitivity is highest.

[0040] Low strain isolation mechanism: When the strain generated by the main load in the area where the strain gauges of the non-target group are located is minimal (εi≈0), then its output Vout_crosstalk≈0.

[0041] Bridge self-balancing mechanism: When non-target strain gauges generate non-zero strain due to structural coupling, but their distribution satisfies ε1≈ε3 and ε2≈ε4, substituting into formula B: Vout_crosstalk∝(ε2+ε3-ε1-ε4)≈(ε4+ε1-ε1-ε4)=0; positive and negative terms cancel each other out, and the output is close to zero.

[0042] Through the above mechanism, the present invention ensures that under rated load, the output coupling of the non-target channel is less than 5% of the target channel output, preferably less than 2%, and more preferably less than 1%.

[0043] Based on the above principles, the present invention provides the following specific implementation methods: Example 1: See Figure 2 As shown in ab, Figure 2ab is a structural schematic diagram of a six-dimensional force-elastic body embodiment with structural decoupling capability. The composite elastic beam 3 of this embodiment includes four vertically distributed elastic beams and eight buffer beams 32. The ends of the eight buffer beams 32 are fixedly connected to the inner wall of the outer mounting ring 2, forming a regular octagonal frame. The opposite ends of the elastic beams are fixedly connected to the corresponding ends of the inner mounting block 1 and the buffer beams 32, respectively. All elastic beams and buffer beams 32 are centrally symmetrically distributed with respect to the central axis of the elastic body and axially symmetrically distributed with respect to at least two orthogonal axes passing through the center of the elastic body. Six sets of strain gauges are distributed at corresponding positions on the elastic beams and / or buffer beams 32. Specifically, two tension strain gauges of FX are disposed on two oppositely disposed buffer beams 32; and two compression strain gauges of FX are disposed on another set of oppositely disposed buffer beams 32; two tension strain gauges of FY are disposed on two oppositely disposed buffer beams 32; and two compression strain gauges of FY are disposed on another set of oppositely disposed buffer beams 32.

[0044] As an optional implementation, under rated uniaxial load, when the output of any target measurement channel is 100%, the output of the other five non-target channels is less than 2% of their own full scale.

[0045] As an optional implementation, the composite elastic beam 3 has a finely machined plane; 24 strain gauges are symmetrically arranged on the same side or opposite sides of the plane of the composite elastic beam 3.

[0046] As an optional implementation, the strain gauges are metal foil strain gauges, silicon strain gauges, or thick film resistors, and each bridge satisfies the initial balance condition R1 / R2 = R3 / R4 when there is no load; where R1, R2, R3, and R4 represent the resistance values ​​of the four arms in the Wheatstone full-bridge circuit, respectively corresponding to the four strain gauges in each measurement dimension.

[0047] As an optional implementation, the elastomer material is stainless steel, aluminum alloy, or titanium alloy.

[0048] This embodiment utilizes a composite structure of four vertical elastic beams and eight buffer beams 32 to form a regular octagonal frame system with multiple symmetries, achieving a significant structural decoupling effect. The regular octagonal frame provides more axes of symmetry, allowing strain gauges measured by FX and FY to be precisely positioned on the optimized buffer beams 32 (instead of the traditional main elastic beams). This fully utilizes the pure strain mode generated by the buffer beams 32 under the target load. Furthermore, by matching the relative positions of the strain gauges (tension and compression groups are respectively arranged on specific opposite buffer beams 32), it aligns with the "relative bridge arm strains have the same sign, adjacent bridge arm strains have different signs" working principle of the Wheatstone full-bridge circuit. This not only improves the sensitivity of the target channel but, more importantly, automatically satisfies the bridge circuit self-balancing condition of "ε1≈ε3 and ε2≈ε4" under non-target loads. This suppresses interdimensional coupling from the mechanical structural source, effectively controlling the coupling error to an excellent level of ≤5%. Simultaneously, the buffer beam 32 structure also enhances the overall stiffness and overload resistance.

[0049] Stress cloud diagram tests were performed on the structure of this embodiment, such as... Figure 8 The coupling error calculation is shown in Table 2 below. (See also...) Figure 8 As shown, Figure 8 This is a strain analysis cloud diagram of Example 1 of a six-dimensional force-elastic body with structural decoupling capability.

[0050] from Figure 8 As can be seen, when measuring the force in the FX direction, the maximum stress is concentrated at the FX measurement channel, and the five measurement channels FY, FZ, MX, MY, and MZ have the same effect.

[0051] Table 2. Coupling error data for Example 1 of a six-dimensional force-elastic body with structural decoupling capability.

[0052] As can be seen from Table 2 above, the coupling error of the present invention is effectively controlled at an excellent level of ≤5%. As shown in the above calculations in this embodiment, the coupling error is less than 1%.

[0053] Example 2 See Figure 3 ac and Figure 9 As shown, the only difference between this embodiment and Embodiment 1 is that the positions of the strain gauges used to measure the X-axis force FX and the strain gauges used to measure the Y-axis force Fy have been interchanged.

[0054] Example 3 See Figure 1As shown in the above analysis, the structure of the six-dimensional force elastomer and the arrangement of the 24 strain gauges in the prior art can be seen from the figure. For example, when measuring the force in the FX direction, the maximum stress is not concentrated at the FX measurement channel, so the measurement error is relatively serious.

[0055] In this embodiment, at least one set of strain gauges for measuring the X-axis force FX is located at a locally softened sensitive element on the composite elastic beam 3 to improve the measurement sensitivity of FX. Similarly, at least one set of strain gauges for measuring the Y-axis force FY is located at a locally softened sensitive element on the composite elastic beam 3 to improve the measurement sensitivity of FY.

[0056] For details, see Figure 4 and Figure 10 As shown, the composite elastic beam 3 in this embodiment includes four vertically distributed elastic beams, wherein: the opposite ends of the elastic beams are fixedly connected to the inner mounting block 1 and the outer mounting ring 2, respectively, and six sets of strain gauges are distributed at corresponding positions on the elastic beams; the elastic beams are provided with recessed portions to allow the strain gauges of FX and FY to be arranged in the high-strain region above the average stress value on the surface of the composite elastic beam 3. In this embodiment, each elastic beam is an independent beam structure.

[0057] The recessed portion of this embodiment includes a through hole 42, which penetrates both opposite sides of the same elastic beam. Strain gauges FX and FY are distributed on the side of the through hole 42.

[0058] In this embodiment, a through hole 42 is provided at one end of the elastic beam near the outer mounting ring 2 as the aforementioned recess, which can concentrate stress at this location. Since the strain gauges for FX and FY are distributed on the side of the through hole 42, the positions of the strain gauges used to measure the X-axis force FX and the strain gauges used to measure the Y-axis force FY are located at the corresponding sensitive units on the composite elastic beam 3 that have undergone localized softening design, thereby achieving stress concentration in the corresponding directions to directionally improve the measurement sensitivity of FX and FY.

[0059] This embodiment utilizes a symmetrical through-hole structure 42 on four independent vertical elastic beams. The through-holes 42 act as stress concentration sources, significantly increasing the strain level in the surrounding area. This allows strain gauges for FX and FY to be positioned in high-strain regions above the average surface stress, enhancing the measurement sensitivity of the target channel. Simultaneously, the symmetrical layout of the through-holes 42 ensures that under the target load, the strain distribution strictly satisfies the working condition of the Wheatstone bridge having the same strain sign for the relative bridge arms and different strain signs for adjacent bridge arms, allowing Vout to reach its theoretical maximum value. More importantly, it automatically forms a bridge self-balancing state of "ε1≈ε3 and ε2≈ε4" under non-target loads, suppressing interdimensional coupling from the mechanical structural source and effectively controlling the coupling error to an excellent level of ≤5%.

[0060] See Figure 9 As shown, from Figure 9 As can be seen, when measuring the force in the FX direction, the maximum stress is concentrated at the FX measurement channel, and the five measurement channels FY, FZ, MX, MY, and MZ have the same effect.

[0061] Example 4 The difference between this embodiment and Embodiment 3 is as follows: See Figure 5 and Figure 11 As shown, the recessed portion of this embodiment includes a groove 41, which is symmetrically arranged on opposite sides of the same elastic beam, and strain gauges FX and FY are distributed on the side of the groove 41.

[0062] In this embodiment, by symmetrically setting groove 41 structures on four independent vertical elastic beams, the groove 41 acts as a stress concentration source, significantly increasing the strain level in the surrounding area. This allows the strain gauges of FX and FY to be arranged in high-strain areas above the average surface stress, thereby improving the measurement sensitivity of the target channel.

[0063] Example 5 The difference between this embodiment and embodiment 4 is as follows: See Figure 5 and Figure 12 As shown, in this embodiment, each elastic beam includes two or more beam columns 311. The two beam columns 311 in the same group are arranged along the corresponding side wall of the inner mounting block 1, and a gap hole 43 is formed between them.

[0064] See Figure 5 And see Figure 12 The two beams 311 of each elastic beam can be arranged in parallel. Or, see [link to relevant documentation]. Figure 13 As shown, there is an included angle between the two beams 311 of each elastic beam.

[0065] In this embodiment, each elastic beam adopts a composite structure of multiple beams and columns 311 and spacer holes 43, which achieves precise control of mechanical properties. The two beams and columns 311 are symmetrically arranged along the inner mounting block 1 to form spacer holes 43, which not only significantly enhances the stiffness and overall stability of the structure in the Z direction, but also effectively blocks the transmission path of non-target loads by using the spacer holes 43 as stress isolation zones. At the same time, the grooves 41 on both sides of the beams and columns 311 work together with the spacer holes 43 to further enhance the strain concentration effect in the FX / FY direction, so that the strain gauges are precisely placed in the high strain region above the average surface stress, thereby improving the sensitivity of the target channel.

[0066] The above embodiments demonstrate that by optimizing the mechanical structure, controlling the strain field, and... Figure 7The Wheatstone full-bridge circuit principle shown (especially the decoupling mechanism based on formula B) is deeply integrated to achieve high-performance hardware-decoupled six-dimensional force sensing. Those skilled in the art can understand this based on the principles revealed by formulas A and B. Figure 4 The electrical bridging method shown allows for adjustments to the shape of the composite beam and the position of the strain gauges. These modifications, which do not deviate from the core concept of this invention, are all within the scope of protection.

[0067] Example 6 See Figure 14 This embodiment is a modified structure of embodiment 1. The composite elastic beam of this embodiment includes four vertically distributed elastic beams and eight buffer beams. The four buffer beams are fixedly connected to form a regular quadrilateral frame. The other four buffer beams are fixedly connected to the end corners of the regular quadrilateral frame and the end corners of the inner mounting block. The opposite ends of the elastic beams are respectively fixed to the outer mounting ring and the middle of the corresponding side of the regular quadrilateral frame.

[0068] The stress cloud diagram of this embodiment is as follows: Figure 14 As shown in the figure, it can be seen that coupling can be significantly reduced.

[0069] Example 7 The present invention also provides a six-dimensional force sensor, comprising the above-mentioned six-dimensional force elastomer with structural decoupling capability, a power supply module providing excitation voltage for each bridge, a signal conditioning circuit for amplifying the differential output signals of each bridge, and a housing.

[0070] In this invention, the composite elastic beam 3 is equipped with high-precision machined strain gauge bonding islands to ensure the repeatability and consistency of strain gauge bonding. The elastomer is integrally machined, and the strain gauges are precisely bonded to the bonding islands using a special adhesive and then cured at a temperature. After bonding, measurements and fine-tuning are required to ensure that each bridge circuit meets the requirements. Figure 7 The initial balance conditions are shown in the diagram (R1 / R2 = R3 / R4). The leads of the six bridge circuits are led out to the signal conditioning board using shielded cables. During calibration, a standard six-dimensional force calibrator is used to apply a unidirectional standard load, the output of each channel is recorded, and the sensitivity matrix is ​​calculated. Actual measurement data shows that the off-diagonal elements (coupling terms) are all less than 5% of the diagonal elements (main sensitivity), verifying the decoupling effect of this invention.

[0071] This embodiment suppresses interdimensional coupling at the source, with a typical coupling error of <2%, significantly better than traditional designs (typically 5%-20%). Figure 7 The full-bridge configuration shown provides a high output signal (mV / V level), and with structural optimization, the sensitivity can reach 10^10. 4Order of magnitude. The strain distribution design based on formula B directly corresponds to the bridge connection method shown in the figure, enabling performance prediction and optimization to move from experience to theory, shortening the development cycle. The full-bridge circuit has temperature self-compensation characteristics, and combined with the symmetrical structure, it has small temperature drift and good long-term stability. By adjusting the local stiffness of the composite beam, sensitivity enhancement can be performed on specific dimensions (such as FZ) to meet customized needs without changing the basic bridge principle shown in the figure.

[0072] The specific features, structures, or characteristics described in this specification may be combined in any suitable manner in one or more embodiments or examples.

[0073] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0074] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A six-dimensional force-elastic body with structural decoupling capability, characterized in that, It includes an inner mounting block and an outer mounting ring arranged coaxially, as well as multiple sets of composite elastic beams connecting the two, wherein: The composite elastic beam is provided with at least 6 groups of 24 strain gauges. The six groups of strain gauges are used to measure the force in the three directions FX, FY, and FZ and the torque in the three directions MX, MY, and MZ, respectively. Each group of strain gauges is electrically connected according to the corresponding Wheatstone full-bridge circuit topology to form six independent measuring bridges. The tensile and compressive polarities of the strain gauges in each group are defined according to their strain direction under the corresponding positive load and correspond to the bridge arm positions in the circuit topology. The structural shape of the composite elastic beam, the arrangement of the strain gauges, and their connection relationships in the entire bridge are coordinated to ensure that when the elastic body is subjected to a load in a single target direction, the strain distribution of the target channel strain gauges causes the entire bridge output to satisfy the formula: Vout ≈ (Vin×GF / 4)×(ε2+ε3-ε1-ε4), and the absolute value of this combined term is sufficiently large; while the strain distribution of the non-target channel strain gauges causes the entire bridge output to be sufficiently minimized due to low strain isolation or the bridge self-balancing mechanism. Among them, the bridge self-balancing mechanism refers to the strain distribution of the non-target channel satisfying ε2+ε3≈ε1+ε4, which makes its output approach zero, thereby achieving a coupling error ≤5%; Where Vout represents the output voltage of the Wheatstone full-bridge circuit, Vin represents the excitation voltage of the Wheatstone full-bridge circuit, GF represents the sensitivity coefficient of the strain gauge, and ε1, ε2, ε3, and ε4 represent the strain values ​​generated by each group of four strain gauges under stress.

2. The six-dimensional force-elastic body with structural decoupling capability according to claim 1, characterized in that, The composite elastic beam comprises four vertically distributed elastic beams and eight buffer beams, wherein: The ends of the eight buffer beams are fixedly connected to the inner wall of the outer mounting ring, forming a regular octagonal frame; the opposite ends of the elastic beams are respectively fixedly connected to the inner mounting block and the corresponding ends of the buffer beams. Alternatively, four of the buffer beams are fixedly connected to form a regular quadrilateral frame, and the other four buffer beams are fixedly connected to the end corners of the regular quadrilateral frame and the end corners of the inner mounting block. The opposite ends of the elastic beam are respectively fixed to the outer mounting ring and the middle of the corresponding side of the regular quadrilateral frame. All elastic beams and the buffer beams are centrally symmetrical about the central axis of the elastic body, and are axially symmetrical about the central axis of the elastic body. The six sets of strain gauges are distributed at corresponding positions on the elastic beam and / or the buffer beam; Among them, the two tensile strain gauges of FX are arranged on two opposite buffer beams, and the two compressive strain gauges of FX are arranged on another set of two opposite buffer beams; The two tensile strain gauges of FY are disposed on two oppositely arranged buffer beams, and the two compressive strain gauges of FY are disposed on another set of two oppositely arranged buffer beams.

3. The six-dimensional force-elastic body with structural decoupling capability according to claim 1, characterized in that, The composite elastic beam comprises four vertically distributed elastic beams, wherein: The two ends of the elastic beam are fixedly connected to the inner mounting block and the outer mounting ring, respectively, and the six sets of strain gauges are distributed at the corresponding positions of the elastic beam. The elastic beam has a recessed portion to allow strain gauges FX and FY to be arranged in the high-strain region above the average stress value on the surface of the composite elastic beam.

4. The six-dimensional force-elastic body with structural decoupling capability according to claim 3, characterized in that, The recessed portion includes a groove, which is symmetrically arranged on opposite sides of the same elastic beam, and strain gauges FX and FY are distributed on the side of the groove; Alternatively, the recess may include a through hole that extends through both opposite sides of the same elastic beam, with strain gauges FX and FY distributed on the sides of the through hole.

5. The six-dimensional force-elastic body with structural decoupling capability according to claim 3, characterized in that, Each of the elastic beams is an independent beam structure, or each of the elastic beams includes two or more beam columns; When the elastic beam includes two or more beams, the two beams in the same group are arranged along the corresponding sidewall of the inner mounting block, and a gap hole is formed between them.

6. The six-dimensional force-elastic body with structural decoupling capability according to claim 1, characterized in that, The strain gauges for FX and FY are arranged in the high-strain region above the average surface stress of the composite elastic beam when subjected to a single load in the FX or FY direction. Under rated uniaxial load, when the output of any target measurement channel is 100%, the output of the other five non-target channels is less than 2% of their own full scale.

7. The six-dimensional force-elastic body with structural decoupling capability according to claim 1, characterized in that, The composite elastic beam has a precision-machined plane; the 24 strain gauges are symmetrically arranged on the same side or opposite sides of the composite elastic beam.

8. The six-dimensional force-elastic body with structural decoupling capability according to claim 1, characterized in that, The strain gauge is a metal foil strain gauge, a silicon strain gauge, or a thick film resistor, and each bridge satisfies the initial balance condition R1 / R2 = R3 / R4 when there is no load. R1, R2, R3, and R4 represent the resistance values ​​of the four arms of the Wheatstone full-bridge circuit, corresponding to the four strain gauges in each measurement dimension.

9. The six-dimensional force-elastic body with structural decoupling capability according to claim 1, characterized in that, The elastomer material is stainless steel, aluminum alloy, or titanium alloy.

10. A six-dimensional force sensor, characterized in that, It includes a six-dimensional force-elastic body with structural decoupling capability as described in any one of claims 1-9, a power supply module that provides excitation voltage for each bridge, a signal conditioning circuit for amplifying the differential output signals of each bridge, and a housing.

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