High-torsion rigid joint torque sensor

Abstract

The utility model discloses a high-torsion rigid joint torque sensor, which comprises a torque sensor flange and a PCB (printed circuit board) arranged on the torque sensor flange, the torque sensor flange is provided with an annular groove, and a thin-wall strain beam is formed at the bottom of the annular groove; at least one strain gauge group is arranged on the thin-wall strain beam, each strain gauge group comprises four front strain gauge pairs which are arranged on the front surface or the back surface of the thin-wall strain beam at equal intervals in the circumferential direction, and each front strain gauge pair comprises a first strain gauge and a second strain gauge; the four first strain gauges and the four second strain gauges of each strain gauge group are connected through a PCB to form a Wheatstone bridge structure. According to the utility model, the thin-wall strain beam fully fills the gap between the outer flange and the inner flange, so that the torsional rigidity can be enhanced, and the reading precision can be ensured.

Description

Technical Field

[0001] This utility model belongs to the field of torque sensors, and in particular relates to a high torsional rigidity joint torque sensor. Background Technology

[0002] When collaborative robots are performing tasks, the varying rigidity of their components generally determines the robot's overall rigidity, which significantly impacts its performance. During operation, the persistent inertia causes the end effector to oscillate when stopped, requiring a settling time for precise positioning. This settling time is related to rigidity; with equal control parameters, better rigidity results in shorter settling times, while poorer rigidity leads to longer settling times. Therefore, collaborative robots require high rigidity. Furthermore, to ensure safety, torque sensors are necessary, making them a crucial component for enhancing the rigidity of collaborative robots.

[0003] Existing torque sensors are mostly beam-structured, with anywhere from 2-4 strain beams to 8 or more. These sensors primarily use metal strain gauges, which are bonded to the same side of the strain beams. Regardless of whether they have 2, 4, or 8 strain beams, existing torque sensors exhibit certain rigidity disadvantages. Torque sensors with fewer strain beams have even worse rigidity, while those with more beams offer slightly better rigidity, but overall, the deformation is relatively large, impacting the rigidity of collaborative robots to some extent. Solving the rigidity problem requires a structural design approach.

[0004] Furthermore, existing torque sensors typically attach metal strain gauges to the same side of the strain beam, leading to crosstalk during torque readings and significant errors in the sensor readings. Moreover, the strain gauges currently used are generally metal and are glued to the strain beam of the torque sensor's elastic body, which cannot guarantee the accuracy and consistency of the attachment, thus amplifying the crosstalk effect. Additionally, existing torque sensors are single-channel designs with no redundancy; if one channel fails, there is no backup channel available. Utility Model Content

[0005] In view of the shortcomings of the prior art, the technical problem to be solved by this utility model is to provide a high torsional rigidity joint torque sensor.

[0006] To solve the above-mentioned technical problems, this utility model provides the following technical solution:

[0007] A high torsional rigidity joint torque sensor includes a torque sensor flange and a PCB circuit board disposed on the torque sensor flange. The torque sensor flange includes a front side and a back side opposite to the front side. An annular groove is provided on the back side or the front side of the torque sensor flange. The portion of the torque sensor flange located outside the annular groove forms an outer flange, and the portion of the torque sensor flange located inside the annular groove forms an inner flange. A thin-walled strain beam is formed at the bottom of the annular groove. At least one strain gauge group is disposed on the thin-walled strain beam. Each strain gauge group includes four pairs of front strain gauges equally spaced along the circumferential direction on the front or back side of the thin-walled strain beam. Each pair of front strain gauges includes a first strain gauge and a second strain gauge. The four first strain gauges and four second strain gauges of each strain gauge group are connected by the PCB circuit board to form a Wheatstone bridge structure.

[0008] Furthermore, each strain gauge group includes a first front strain gauge pair, a second front strain gauge pair, a third front strain gauge pair, and a fourth front strain gauge pair arranged at equal intervals along the circumferential direction on the thin-walled strain beam. The first end of the first strain gauge of the first front strain gauge pair is electrically connected to the first end of the first strain gauge of the fourth front strain gauge pair. The second end of the first strain gauge of the fourth front strain gauge pair is electrically connected to the second end of the second strain gauge of the fourth front strain gauge pair. The first end of the second strain gauge of the fourth front strain gauge pair is electrically connected to the first end of the second strain gauge of the third front strain gauge pair.

[0009] The second end of the first strain gauge of the first front strain gauge pair is electrically connected to the second end of the second strain gauge of the first front strain gauge pair; the first end of the second strain gauge of the first front strain gauge pair is electrically connected to the first end of the second strain gauge of the second front strain gauge pair; the second end of the second strain gauge of the second front strain gauge pair is electrically connected to the second end of the first strain gauge of the second front strain gauge pair; the first end of the first strain gauge of the second front strain gauge pair is electrically connected to the first end of the first strain gauge of the third front strain gauge pair; and the second end of the first strain gauge of the third front strain gauge pair is electrically connected to the second end of the second strain gauge of the third front strain gauge pair.

[0010] Furthermore, in the strain gauge group, one of the front strain gauge pairs is designated as the positive strain gauge pair, and the front strain gauge pair opposite to the positive strain gauge pair is designated as the ground strain gauge pair. The remaining two front strain gauge pairs in the strain gauge group are the output positive terminal strain gauge pair and the output negative terminal strain gauge pair, respectively. The second end of the first strain gauge of the positive strain gauge pair serves as the voltage input terminal of the Wheatstone bridge structure for connecting to the positive terminal of the power supply voltage. The second end of the first strain gauge of the ground strain gauge pair serves as the ground terminal of the Wheatstone bridge structure for grounding. The second end of the first strain gauge of the output positive terminal strain gauge pair serves as the output positive terminal of the Wheatstone bridge structure for connecting to the positive terminal of the measuring device. The second end of the first strain gauge of the output negative terminal strain gauge pair serves as the output negative terminal of the Wheatstone bridge structure for connecting to the negative terminal of the measuring device.

[0011] Furthermore, the four pairs of front strain gauges are disposed on the front side of the thin-walled strain beam, and the strain gauge group also includes four pairs of back strain gauges disposed on the back side of the thin-walled strain beam, with each pair of back strain gauges corresponding to one of the pairs of front strain gauges; each pair of back strain gauges includes a third strain gauge and a fourth strain gauge, the third strain gauge being disposed opposite to the first strain gauge of the corresponding front strain gauge pair, and the fourth strain gauge being disposed opposite to the second strain gauge of the corresponding front strain gauge pair; a first strain gauge wiring hole is disposed on one side of each third strain gauge, and a second strain gauge wiring hole is disposed on one side of each fourth strain gauge; each third strain gauge is connected in parallel with the first strain gauge at the corresponding position, and each fourth strain gauge is connected in parallel with the second strain gauge at the corresponding position.

[0012] Furthermore, the PCB circuit board is ring-shaped and is fixed to the front of the inner flange with insulating adhesive; a grounding hole is provided on the PCB circuit board, and a grounding threaded hole is provided on the front of the inner flange at the position corresponding to the grounding hole. A grounding screw is passed through the grounding hole and is screwed and fixed in the grounding threaded hole, thereby realizing the electrical connection between the grounding hole and the grounding threaded hole.

[0013] The PCB circuit board has a notch at the position of each front strain gauge pair, exposing the third and fourth strain gauges. A first and second pad are provided on one side of the notch corresponding to the position of the first strain gauge, and a third and fourth pad are provided on the position of the second strain gauge. The first end of each of the first and third strain gauges is connected to the corresponding first pad via a wire, and the second end is connected to the corresponding second pad via a wire. Similarly, the first end of each of the second and fourth strain gauges is connected to the corresponding third pad via a wire, and the second end is connected to the corresponding fourth pad via a wire.

[0014] Furthermore, both the first and second strain gauges are silicon strain gauges, which are fixedly mounted on the thin-walled strain beam using a glass micro-melting sintering process.

[0015] Furthermore, the first and second strain gauges of each of the aforementioned front strain gauge pairs are symmetrically arranged, and the axis of symmetry of the first and second strain gauges passes through the center of the inner flange; the angle between the axis of the first strain gauge and the axis of the second strain gauge and the axis of symmetry is 45°.

[0016] Furthermore, the thickness of the thin-walled strain beam is determined by simulation software based on the strain magnitude requirements of the torque sensor; the first strain gauge and the second strain gauge are set in the region of maximum strain of the thin-walled strain beam, and the region of maximum strain of the thin-walled strain beam is determined by the simulation results of finite element simulation software.

[0017] Furthermore, the torque sensor flange is made of rigid material; the inner flange has a through hole in the middle, and a plurality of inner flange threaded holes are provided around the periphery of the through hole in the circumferential direction; a raised ring is provided on the back of the inner flange corresponding to the periphery of the plurality of inner flange threaded holes; a plurality of outer flange threaded holes are provided on the outer flange in the circumferential direction.

[0018] Furthermore, the torque sensor includes two strain gauge groups, namely a first strain gauge group and a second strain gauge group, wherein the spacing between each front strain gauge pair in the first strain gauge group and the adjacent front strain gauge pair in the second strain gauge group is equal.

[0019] In this invention, the thin-walled strain beam is a thin circular ring that completely fills the gap between the outer and inner flanges, forming a unified whole without any hollowing out. This enhances torsional rigidity. Furthermore, by controlling the thickness of the thin-walled strain beam, deformation can be introduced to compress the strain gauges, thus improving both rigidity and reading accuracy. By connecting the strain gauges to form a Wheatstone bridge, torque measurement can be completed using only one AD sampling, making measurement more convenient. A special bridge connection method achieves symmetry in the overall circuit structure, reducing crosstalk. By placing strain gauges on both the front and back of the thin-walled strain beam, the influence of external forces in directions other than the torque direction can be largely eliminated, significantly improving the measurement accuracy of the torque value. Simulations placing the strain gauges in the area of ​​maximum strain on the thin-walled strain beam, with the first and second strain gauges symmetrically positioned, further improve the accuracy of torque testing. Silicon strain gauges are used and fixed using a glass micro-fusion sintering process, which improves sensitivity and anti-interference performance compared to metal strain gauges. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0021] Figure 1 This is a schematic diagram of the structure of the torque sensor flange in one embodiment of a high torsional rigidity joint torque sensor of this utility model.

[0022] Figure 2 This is a top view of the torque sensor flange.

[0023] Figure 3 for Figure 2 A schematic diagram of the structure after the PCB circuit board of the torque sensor flange is installed.

[0024] Figure 4 for Figure 2 Enlarged view of point A in the middle.

[0025] Figure 5 To be Figure 4 A schematic diagram of the combined structure of the first and second strain gauges with the opening facing inwards.

[0026] Figure 6 The circuit diagram shows the Wheatstone bridge structure formed by connecting the front strain gauge pairs of the first strain gauge group.

[0027] Figure 7 This is a circuit diagram of the Wheatstone bridge structure formed by connecting the front and back strain gauge pairs of the first strain gauge group.

[0028] Figure 8 This is a circuit diagram of the Wheatstone bridge structure formed by connecting the front and back strain gauge pairs of the second strain gauge group.

[0029] The diagrams in the instruction manual are labeled as follows:

[0030] Torque sensor flange-100; outer flange-110; outer flange threaded hole-111; inner flange-120; through hole-121; inner flange threaded hole-122; inner flange pin hole-123; cable spool threaded hole-124; grounding threaded hole-125; convex ring-126.

[0031] First front-facing strain gauge pair -131, 135; Second front-facing strain gauge pair -132, 136; Third front-facing strain gauge pair -133, 137; Fourth front-facing strain gauge pair -134, 138; First strain gauge -141; Second strain gauge -142; Third strain gauge -143; Fourth strain gauge -144; Annular groove -150; Thin-walled strain beam -160; First strain gauge wiring hole -161; Second strain gauge wiring hole -162; First back-facing strain gauge pair -171, 175; Second back-facing strain gauge pair -172, 176; Third back-facing strain gauge pair -173, 177; Fourth back-facing strain gauge pair -174, 178;

[0032] PCB circuit board - 200; First pad - 201; Second pad - 202; Third pad - 203; Fourth pad - 204; Grounding hole - 210; Notch - 220. Detailed Implementation

[0033] The following specific examples illustrate the implementation of this utility model. The illustrations provided in the following embodiments are only schematic representations of the basic concept of this utility model. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0034] Please see Figure 1 , Figure 2 and Figure 3 An embodiment of a high torsional rigidity joint torque sensor of this utility model includes a torque sensor flange 100 and a PCB circuit board 200 disposed on the torque sensor flange 100. The torque sensor flange 100 includes a front side and a back side opposite to the front side. An annular groove 150 is provided on the torque sensor flange 100, and the annular groove 150 is generally disposed on the back side of the torque sensor flange 100. Of course, the annular groove 150 can also be disposed on the front side of the torque sensor flange 100. The portion of the torque sensor flange 100 located outside the annular groove 150 forms an outer flange 110, and the portion of the torque sensor flange 100 located inside the annular groove 150 forms an inner flange 120. The bottom of the annular groove 120 forms a thin-walled strain beam 160; the thickness of the thin-walled strain beam 160 (i.e., the residual thickness of the annular groove 150) is generally determined by simulation software according to the strain magnitude requirements of the torque sensor. The torque sensor flange 100 is made of a high-hardness, high-elongation rigid material (such as stainless steel). The structure composed of the outer flange 110, the inner flange 120, and the thin-walled strain beam 160 can be called an elastic body.

[0035] The inner flange 120 has a through hole 121 in the middle, and a plurality of inner flange threaded holes 122 are provided around the through hole 121 along the circumferential direction. The through hole 121 is also generally provided with a wire spool threaded hole 124 and an inner flange pin hole 123. A raised ring 126 is provided on the back of the inner flange 120 corresponding to the periphery of the plurality of inner flange threaded holes 122. The outer flange 110 has a plurality of outer flange threaded holes 111 along the circumferential direction. The inner flange threaded holes 122 and outer flange threaded holes 111 are used to connect different joints. The wire spool threaded hole 124 is used to connect a wire spool (not shown in the figure) to facilitate wire routing. The inner flange pin hole 123 is used to connect a load block via a pin (not shown in the figure). The shear force transmitted through the pin can improve the transmitted torque.

[0036] In this embodiment, two strain gauge groups are provided on the thin-walled strain beam 160, namely the first strain gauge group and the second strain gauge group. Of course, in other embodiments, one, three, or more strain gauge groups may be provided. Each strain gauge group includes four pairs of front-facing strain gauges evenly spaced along the circumferential direction on the front side of the thin-walled strain beam 160. When the pairs of front-facing strain gauges are provided on only one side of the thin-walled strain beam 160, they are generally provided on the front side of the thin-walled strain beam 160. Of course, in other embodiments, the four pairs of front-facing strain gauges may also be provided on the back side of the thin-walled strain beam 160. Each pair of front-facing strain gauges includes a first strain gauge 141 and a second strain gauge 142. The first strain gauge 141 and the second strain gauge 142 are generally provided in the region of maximum strain of the thin-walled strain beam 160, which can be determined by simulation results from finite element simulation software. According to the simulation results, the region with the largest strain of the thin-walled strain beam 160 is an annular region. Therefore, when setting the front strain gauge pairs, it is only necessary to ensure the relative positions between each front strain gauge pair.

[0037] The first strain gauge 141 and the second strain gauge 142 of each front strain gauge pair are symmetrically arranged, and the axis of symmetry of the first strain gauge 141 and the second strain gauge 142 passes through the center of the inner flange 120. The axis of the first strain gauge 141 and the axis of the second strain gauge 142 form a certain angle. In this embodiment, the angle between the axis of the first strain gauge 141 and the axis of the second strain gauge 142 and the axis of symmetry is 45°. That is, the angle between the axis of the first strain gauge 141 and the axis of the second strain gauge 142 is 90°, at which point the accuracy of torque testing is the highest.

[0038] Please see Figure 4 The "figure-eight" structure formed by the combination of the first strain gauge 141 and the second strain gauge 142 can have its opening facing outwards. Please refer to... Figure 5The “figure-eight” structure formed by combining the first strain gauge 141 and the second strain gauge 142 can also have its opening facing inward, as long as the angle between the axis of the first strain gauge 141 and the axis of the second strain gauge 142 is 90°.

[0039] Each strain gauge group includes a first front strain gauge pair, a second front strain gauge pair, a third front strain gauge pair, and a fourth front strain gauge pair arranged at equal intervals along the circumferential direction on the thin-walled strain beam 160. In this embodiment, the first strain gauge group includes a first front strain gauge pair 131, a second front strain gauge pair 132, a third front strain gauge pair 133, and a fourth front strain gauge pair 134 arranged at equal intervals along the circumferential direction on the front of the thin-walled strain beam 160; the second strain gauge group includes a first front strain gauge pair 135, a second front strain gauge pair 136, a third front strain gauge pair 137, and a fourth front strain gauge pair 138 arranged at equal intervals along the circumferential direction on the front of the thin-walled strain beam 160. The eight pairs of frontal strain gauges are evenly spaced on the thin-walled strain beam 160. Specifically, the angle between the axis of symmetry of the first strain gauge 141 and the second strain gauge 142 in each pair of frontal strain gauges in the first strain gauge group and the axis of symmetry of the first strain gauge 141 and the second strain gauge 142 in the adjacent pair of frontal strain gauges in the second strain gauge group is 45°. For example, the angle between the axis of symmetry of the first strain gauge 141 and the second strain gauge 142 in the first frontal strain gauge pair 131 and the axis of symmetry of the first strain gauge 141 and the second strain gauge 142 in the first frontal strain gauge pair 135 is also 45°.

[0040] The first strain gauges 141 and second strain gauges 142 (a total of eight strain gauges) on the four front strain gauge pairs of each strain gauge group are connected by a PCB circuit board 200 to form a Wheatstone bridge structure. The Wheatstone bridge structure of each strain gauge group forms a data acquisition channel. For example, in the first strain gauge group, the first end of the first strain gauge 141 of the first front strain gauge pair 131 is electrically connected to the first end of the first strain gauge 141 of the fourth front strain gauge pair 134, the second end of the first strain gauge 141 of the fourth front strain gauge pair 134 is electrically connected to the second end of the second strain gauge 142 of the fourth front strain gauge pair 134, and the first end of the second strain gauge 142 of the fourth front strain gauge pair 134 is electrically connected to the first end of the second strain gauge 142 of the third front strain gauge pair 133. The second end of the first strain gauge 141 of the first front strain gauge pair 131 is electrically connected to the second end of the second strain gauge 142 of the first front strain gauge pair 131. The first end of the second strain gauge 142 of the first front strain gauge pair 131 is electrically connected to the first end of the second strain gauge 142 of the second front strain gauge pair 132. The second end of the second strain gauge 142 of the second front strain gauge pair 132 is electrically connected to the second end of the first strain gauge 141 of the second front strain gauge pair 132. The first end of the first strain gauge 141 of the second front strain gauge pair 132 is electrically connected to the first end of the first strain gauge 141 of the third front strain gauge pair 133. The second end of the first strain gauge 141 of the third front strain gauge pair 133 is electrically connected to the second end of the second strain gauge 142 of the third front strain gauge pair 133.

[0041] Please refer to the circuit structure formed after connection. Figure 6 Wherein, P1-1 represents the first strain gauge 141 of the first frontal strain gauge pair 131, P2-1 represents the second strain gauge 142 of the first frontal strain gauge pair 131; P3-1 represents the first strain gauge 141 of the second frontal strain gauge pair 132, P4-1 represents the second strain gauge 142 of the second frontal strain gauge pair 132; P5-1 represents the first strain gauge 141 of the third frontal strain gauge pair 133, P6-1 represents the second strain gauge 142 of the third frontal strain gauge pair 133; P7-1 represents the first strain gauge 141 of the fourth frontal strain gauge pair 134, and P8-1 represents the second strain gauge 142 of the fourth frontal strain gauge pair 134. Point A in the circuit is the connection end of the first strain gauge 141 and the second strain gauge 142 of the first front strain gauge pair 131. Point F in the circuit is the connection end of the first strain gauge 141 and the second strain gauge 142 of the second front strain gauge pair 132. Point H in the circuit is the connection end of the first strain gauge 141 and the second strain gauge 142 of the third front strain gauge pair 133. Point C in the circuit is the connection end of the first strain gauge 141 and the second strain gauge 142 of the fourth front strain gauge pair 134.

[0042] Using the above connection method, regardless of which front strain gauge pair's first strain gauge 141 and second strain gauge 142 connection terminal is viewed from, the actual placement positions of the two strain gauges in the circuit are completely symmetrical, thus achieving symmetry and reducing crosstalk in the circuit. If the first strain gauge 141 and second strain gauge 142 of each front strain gauge pair are connected in the same order for bridging, this symmetrical effect cannot be achieved. Furthermore, using the above connection method, any one of the front strain gauge pairs in the strain gauge group can be used as the positive strain gauge pair, without limiting it to a specific position. In this case, the front strain gauge pair opposite the positive strain gauge pair is the grounded strain gauge pair, and the remaining two front strain gauge pairs in the strain gauge group are the output positive terminal strain gauge pair and the output negative terminal strain gauge pair, respectively. The second end of the first strain gauge 141 of the positive strain gauge pair (i.e., the connection end of the first strain gauge 141 and the second strain gauge 142) serves as the voltage input terminal of the Wheatstone bridge structure for connecting to the positive terminal of the power supply voltage (i.e., VCC terminal, generally connected to +5V voltage). The second end of the first strain gauge 141 of the ground strain gauge pair serves as the ground terminal of the Wheatstone bridge structure for grounding (i.e., GND terminal). The second end of the first strain gauge 141 of the output positive strain gauge pair serves as the output positive terminal of the Wheatstone bridge structure for connecting to the positive terminal of the measuring equipment. The second end of the first strain gauge 141 of the output negative strain gauge pair serves as the output negative terminal of the Wheatstone bridge structure for connecting to the negative terminal of the measuring equipment.

[0043] In this embodiment, the first front strain gauge pair 131 is used as the positive strain gauge pair, that is, the second end of the first strain gauge 141 of the first front strain gauge pair 131 is used as the voltage input terminal of the Wheatstone bridge structure, the second end of the first strain gauge 141 of the second front strain gauge pair 132 is used as the negative output terminal of the Wheatstone bridge structure, the second end of the first strain gauge 141 of the third front strain gauge pair 133 is used as the ground terminal of the Wheatstone bridge structure, and the second end of the first strain gauge 141 of the fourth front strain gauge pair 134 is used as the positive output terminal of the Wheatstone bridge structure. Of course, due to the symmetry of the circuit structure in this embodiment, the second front strain gauge pair 132 can also be used as the positive strain gauge pair, that is, the second end of the first strain gauge 141 of the second front strain gauge pair 132 is used as the voltage input terminal of the Wheatstone bridge structure, the second end of the first strain gauge 141 of the third front strain gauge pair 133 is used as the negative output terminal of the Wheatstone bridge structure, the second end of the first strain gauge 141 of the fourth front strain gauge pair 134 is used as the ground terminal of the Wheatstone bridge structure, and the second end of the first strain gauge 141 of the first front strain gauge pair 131 is used as the positive output terminal of the Wheatstone bridge structure; at this time, the strain gauge positions in the circuit are still completely symmetrical.

[0044] To further reduce crosstalk, the strain gauge group may also include four pairs of back strain gauges disposed on the back side of the thin-walled strain beam, each pair corresponding one-to-one with a pair of front strain gauges. In this embodiment, back strain gauge pairs 171, 172, 173, 174, 175, 176, 177, and 178 are provided. Specifically, the back strain gauge pair 171 corresponds to the front strain gauge pair 131, the back strain gauge pair 172 corresponds to the front strain gauge pair 132, the back strain gauge pair 173 corresponds to the front strain gauge pair 133, the back strain gauge pair 174 corresponds to the front strain gauge pair 134, the back strain gauge pair 175 corresponds to the front strain gauge pair 135, the back strain gauge pair 176 corresponds to the front strain gauge pair 136, the back strain gauge pair 177 corresponds to the front strain gauge pair 137, and the back strain gauge pair 178 corresponds to the front strain gauge pair 138.

[0045] Each of the back-side strain gauge pairs includes a third strain gauge 143 and a fourth strain gauge 144. The third strain gauge 143 is disposed opposite to the first strain gauge 141 of the corresponding front-side strain gauge pair, and the fourth strain gauge 144 is disposed opposite to the second strain gauge 142 of the corresponding front-side strain gauge pair. That is, the third strain gauge 143 and the fourth strain gauge 144 of the back-side strain gauge pair are also symmetrically arranged along the axis of symmetry passing through the center of the inner flange 120 in the region of the thin-walled strain beam 160 where the strain is the largest, and the angle between the axis of the third strain gauge 143 and the axis of the fourth strain gauge 144 is also 90°.

[0046] Each of the third strain gauges 143 is connected in parallel with the corresponding first strain gauge 141, and each of the fourth strain gauges 144 is connected in parallel with the corresponding second strain gauge 142. A first strain gauge wiring hole 161 is provided on one side of each third strain gauge 143, and a second strain gauge wiring hole 162 is provided on one side of each fourth strain gauge 144 to facilitate wiring. In this embodiment, the first strain gauge 141, second strain gauge 142, third strain gauge 143, and fourth strain gauge 144 are all silicon strain gauges, which can be fixedly mounted on the thin-walled strain beam 160 using a glass micro-melting sintering process. Using silicon strain gauges and fixing them to the thin-walled strain beam 160 via sintering improves sensitivity and anti-interference performance compared to bonding metal strain gauges.

[0047] After the third strain gauge 143 and the fourth strain gauge 144 are installed on the back of the thin-walled strain beam 160, the resulting circuit structure is shown in the figure. Figure 7Wherein, P1-2 represents the third strain gauge 143 of the first back-side strain gauge pair 171, P2-2 represents the fourth strain gauge 144 of the first back-side strain gauge pair 171; P3-2 represents the third strain gauge 143 of the second back-side strain gauge pair 172, P4-2 represents the fourth strain gauge 144 of the second back-side strain gauge pair 172; P5-2 represents the third strain gauge 143 of the third back-side strain gauge pair 173, P6-2 represents the fourth strain gauge 144 of the third back-side strain gauge pair 173; P7-2 represents the third strain gauge 143 of the fourth back-side strain gauge pair 174, and P8-2 represents the fourth strain gauge 144 of the fourth back-side strain gauge pair 174. In this case, it is equivalent to turning the first strain gauge 141 and the third strain gauge 143 at the corresponding positions into a single strain gauge, and turning the second strain gauge 142 and the fourth strain gauge 144 at the corresponding positions into a single strain gauge, while the operating principle of the circuit remains unchanged.

[0048] Similarly, in the second strain gauge group, the first strain gauge 141 and the second strain gauge 142 of the four front-facing strain gauge pairs, and the third strain gauge 143 and the fourth strain gauge 144 of the four back-facing strain gauge pairs, totaling sixteen strain gauges (eight strain gauges if only front-facing strain gauge pairs are used), are also connected via PCB circuit board 200 to form a Wheatstone bridge structure, with the connection method being the same as that of the first strain gauge group. Please refer to [link / reference]. Figure 8 This is a circuit diagram showing the connection of four first strain gauges 141, four second strain gauges 142, four third strain gauges 143, and four fourth strain gauges 144 in the second strain gauge group. Specifically, R1-1 represents the first strain gauge 141 of the first front strain gauge pair 135; R1-2 represents the third strain gauge 143 of the first front strain gauge pair 135; R2-1 represents the second strain gauge 142 of the first front strain gauge pair 135; R2-2 represents the fourth strain gauge 144 of the first front strain gauge pair 135; R3-1 represents the first strain gauge 141 of the second front strain gauge pair 136; R3-2 represents the third strain gauge 143 of the second front strain gauge pair 136; R4-1 represents the second strain gauge 142 of the second front strain gauge pair 136; and R4-2 represents the fourth strain gauge 144 of the second front strain gauge pair 136. 4; R5-1 represents the first strain gauge 141 of the third frontal strain gauge for 137, R5-2 represents the third strain gauge 143 of the third frontal strain gauge for 137; R6-1 represents the second strain gauge 142 of the third frontal strain gauge for 137, R6-2 represents the fourth strain gauge 144 of the third frontal strain gauge for 137; R7-1 represents the first strain gauge 141 of the fourth frontal strain gauge for 138, R7-2 represents the third strain gauge 143 of the fourth frontal strain gauge for 138; R8-1 represents the second strain gauge 142 of the fourth frontal strain gauge for 138, R8-2 represents the fourth strain gauge 144 of the fourth frontal strain gauge for 138.

[0049] Please continue reading. Figure 3 The PCB circuit board 200 is annular and is bonded to the front of the inner flange 120 with insulating adhesive. A grounding hole 210 is provided on the PCB circuit board 200, and a grounding threaded hole 125 is provided on the front of the inner flange 120 corresponding to the grounding hole 210. A grounding screw (not shown in the figure) passes through the grounding hole 210 and is screwed into the grounding threaded hole 125, thereby achieving an electrical connection between the grounding hole 210 and the grounding threaded hole 125, so that the PCB circuit board 200 can be grounded through the grounding hole 210 and the grounding screw.

[0050] The PCB circuit board 200 has a notch 220 at the position corresponding to each front strain gauge pair, the notch 220 exposing the first strain gauge 141 and the second strain gauge 142 of the front strain gauge pair, so as to facilitate the connection of the first strain gauge 141 and the second strain gauge 142 to the pads via leads. The pads include a first pad 201 and a second pad 202 provided on one side of the notch 220 corresponding to the position of the first strain gauge 141, and a third pad 203 and a fourth pad 204 provided on the position of the second strain gauge 142.

[0051] Each of the first strain gauges 141 and third strain gauges 143 has its first end connected to the corresponding first pad 201 via a wire, and its second end connected to the corresponding second pad 202 via a wire, thereby achieving a parallel connection between the first strain gauges 141 and third strain gauges 143 at corresponding positions. The wire connecting the first and second ends of the third strain gauge 143 passes through the first strain gauge trace hole 161 and connects to the first pad 201 and the second pad 202. Similarly, each of the second strain gauges 142 and fourth strain gauges 144 has its first end connected to the corresponding third pad 203 via a wire, and its second end connected to the corresponding fourth pad 204 via a wire, thereby achieving a parallel connection between the second strain gauges 142 and fourth strain gauges 144 at corresponding positions. The wire connecting the first and second ends of the fourth strain gauge 144 passes through the second strain gauge trace hole 162 and connects to the third pad 203 and the fourth pad 204. Of course, the PCB circuit board 200 also has printed wires connecting each pad to achieve... Figure 7 and Figure 8 The circuit structure shown is shown.

[0052] The working principle of this embodiment is as follows:

[0053] Please see Figures 1 to 8Assuming the collaborative robot's joints include a first joint and a second joint, in use, the output end of the first joint is connected to the outer flange 110 and fastened through the threaded hole 111 of the outer flange. The input end of the second joint is connected to the inner flange 120 and fastened through the threaded hole 122 of the inner flange. The load block is connected to the pin hole 123 of the inner flange using a pin, which improves the torque transmission of the inner flange 120. When relative movement occurs between the first and second joints, the thin-walled strain beam 160 deforms. During deformation, it stretches or compresses the silicon strain gauge, thereby generating voltage and converting it into torque value. Taking the two strain gauge groups in this embodiment as an example, the two strain gauge groups can form two channels for torque reading. Under normal use, only the first channel formed by the silicon strain gauges of the first strain gauge group can be used, and the second channel formed by the silicon strain gauges of the second strain gauge group is used as a backup in case the first channel fails.

[0054] by Figure 7 Taking the circuit in the example as an example, when measuring torque, the circuit will be used to measure torque. Figure 7 Point A of the circuit is connected to the power supply voltage VCC, and point H of the circuit is grounded; point C of the circuit is connected to the positive terminal of the measuring equipment, and point F of the circuit is connected to the negative terminal of the measuring equipment. Assume that the resistance of each silicon strain gauge is R, and the strain coefficient is Ks; taking a clockwise torque as an example, let the strain of each silicon strain gauge be ΔL and the resistance change be ΔR. Then the resistance of P1_1, P1_2, P3_1, P3_2, P5_1, P5_2, P7_1, and P7_2 increases by (R+ΔR), and the resistance of P2_1, P2_2, P4_1, P4_2, P6_1, P6_2, P8_1, and P8_2 decreases by (R-ΔR). At this time:

[0055] R A_B =R B_C =R F_G =R G_H = (R + ΔR) / 2

[0056] R A_E =R E_F =R C_D＝ R D_H = (R-ΔR) / 2

[0057] In the formula, R A_B express Figure 6 The resistance between points A and B is calculated, and so on for the rest.

[0058] ΔR=Ks×ΔL×R

[0059] V = V IN+ -V IN-

[0060] =ΔR / R×Vcc

[0061] =Ks×ΔL×Vcc

[0062] In the formula, V represents the measuring voltage of the measuring device; V IN+ V represents the voltage at point C. IN- V represents the voltage at point F. When a torque other than the torsional direction is applied, V remains almost constant. Therefore, with this bridging method, the torque can be measured with only one AD sampling, without measuring the deformation of each strain gauge; and it can reduce crosstalk caused by forces in directions other than torsion, thus effectively measuring the magnitude of the torque.

[0063] Existing torque sensors have insufficient anti-crosstalk performance, and the torque readings are easily affected by bending moment, axial force, and radial force, resulting in inaccuracy. This embodiment aims to solve the crosstalk problem, reduce the impact of crosstalk on accuracy, and thus improve accuracy; it has the following main advantages:

[0064] (1) The thin-walled strain beam 160 is a thin ring. Compared with the torque sensor with multiple strain beams distributed, this embodiment fills the gap between the outer flange 110 and the inner flange 120 completely. There is no need to limit the width and number of the thin-walled strain beam 160. The thin-walled strain beam 160, the outer flange 110 and the inner flange 120 form a whole that is not hollowed out, which can strengthen the torsional rigidity. At the same time, by controlling the thickness of the thin-walled strain beam 160, the deformation can be used to squeeze the strain gauge, which can improve the rigidity and ensure the reading accuracy.

[0065] (2) By connecting the strain gauges to form a Wheatstone bridge, torque measurement can be completed with just one AD sampling, making the measurement more convenient.

[0066] (3) The symmetry of the overall circuit structure is achieved through a special bridge connection method, which reduces the crosstalk of the circuit.

[0067] (4) By simulating the setting of each strain gauge in the area of ​​the largest strain of the thin-walled strain beam 160, and setting the first strain gauge 141 and the second strain gauge 142 symmetrically at a 90° angle, the accuracy of the torque test can be further improved.

[0068] (5) Silicon strain gauges are used and fixed by glass micro-melting sintering process, which can improve sensitivity and anti-interference performance.

[0069] (6) By setting strain gauges on the front and back sides of the thin-walled strain beam 160, the influence of external forces in directions other than the torque direction can be basically eliminated.

[0070] (7) The dual-channel structure enables redundant design, ensuring normal operation even if one channel fails.

[0071] The above embodiments only illustrate preferred implementations of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A high torsional rigidity joint torque sensor, characterized in that: The device includes a torque sensor flange and a PCB circuit board mounted on the torque sensor flange. The torque sensor flange includes a front side and a back side opposite to the front side. An annular groove is provided on the back side or the front side of the torque sensor flange. The portion of the torque sensor flange located outside the annular groove forms an outer flange, and the portion of the torque sensor flange located inside the annular groove forms an inner flange. A thin-walled strain beam is formed at the bottom of the annular groove. At least one strain gauge group is provided on the thin-walled strain beam. Each strain gauge group includes four pairs of front strain gauges evenly spaced along the circumferential direction on the front or back side of the thin-walled strain beam. Each pair of front strain gauges includes a first strain gauge and a second strain gauge. The four first strain gauges and four second strain gauges of each strain gauge group are connected by the PCB circuit board to form a Wheatstone bridge structure.

2. The high torsional rigidity joint torque sensor as described in claim 1, characterized in that: Each strain gauge group includes a first front strain gauge pair, a second front strain gauge pair, a third front strain gauge pair, and a fourth front strain gauge pair arranged at equal intervals along the circumferential direction on the thin-walled strain beam. The first end of the first strain gauge of the first front strain gauge pair is electrically connected to the first end of the first strain gauge of the fourth front strain gauge pair. The second end of the first strain gauge of the fourth front strain gauge pair is electrically connected to the second end of the second strain gauge of the fourth front strain gauge pair. The first end of the second strain gauge of the fourth front strain gauge pair is electrically connected to the first end of the second strain gauge of the third front strain gauge pair. The second end of the first strain gauge of the first front strain gauge pair is electrically connected to the second end of the second strain gauge of the first front strain gauge pair; the first end of the second strain gauge of the first front strain gauge pair is electrically connected to the first end of the second strain gauge of the second front strain gauge pair; the second end of the second strain gauge of the second front strain gauge pair is electrically connected to the second end of the first strain gauge of the second front strain gauge pair; the first end of the first strain gauge of the second front strain gauge pair is electrically connected to the first end of the first strain gauge of the third front strain gauge pair; and the second end of the first strain gauge of the third front strain gauge pair is electrically connected to the second end of the second strain gauge of the third front strain gauge pair.

3. A high torsional rigidity joint torque sensor as described in claim 2, characterized in that: In the strain gauge group, one of the front strain gauge pairs is designated as the positive strain gauge pair, and the opposite front strain gauge pair is designated as the ground strain gauge pair. The remaining two front strain gauge pairs in the strain gauge group are the output positive terminal strain gauge pair and the output negative terminal strain gauge pair, respectively. The second end of the first strain gauge of the positive strain gauge pair serves as the voltage input terminal of the Wheatstone bridge structure and is used to connect to the positive terminal of the power supply voltage. The second end of the first strain gauge of the ground strain gauge pair serves as the ground terminal of the Wheatstone bridge structure and is used for grounding. The second end of the first strain gauge of the output positive terminal strain gauge pair serves as the output positive terminal of the Wheatstone bridge structure and is used to connect to the positive terminal of the measuring device. The second end of the first strain gauge of the output negative terminal strain gauge pair serves as the output negative terminal of the Wheatstone bridge structure and is used to connect to the negative terminal of the measuring device.

4. A high torsional rigidity joint torque sensor as described in claim 3, characterized in that: The four pairs of front strain gauges are disposed on the front side of the thin-walled strain beam. The strain gauge group also includes four pairs of back strain gauges disposed on the back side of the thin-walled strain beam, each pair of back strain gauges corresponding to one pair of front strain gauges. Each pair of back strain gauges includes a third strain gauge and a fourth strain gauge. The third strain gauge is disposed opposite to the first strain gauge of the corresponding front strain gauge pair, and the fourth strain gauge is disposed opposite to the second strain gauge of the corresponding front strain gauge pair. A first strain gauge wiring hole is disposed on one side of each third strain gauge, and a second strain gauge wiring hole is disposed on one side of each fourth strain gauge. Each third strain gauge is connected in parallel with the first strain gauge at the corresponding position, and each fourth strain gauge is connected in parallel with the second strain gauge at the corresponding position.

5. A high torsional rigidity joint torque sensor as described in claim 4, characterized in that: The PCB circuit board is ring-shaped and is fixed to the front of the inner flange with insulating adhesive. The PCB circuit board is provided with a grounding hole, and the front of the inner flange is provided with a grounding threaded hole at the position corresponding to the grounding hole. A grounding screw is passed through the grounding hole and is screwed and fixed in the grounding threaded hole, thereby realizing the electrical connection between the grounding hole and the grounding threaded hole. The PCB circuit board has a notch at the position of each front strain gauge pair, exposing the first strain gauge and the second strain gauge. A first pad and a second pad are provided on one side of the notch at the position of the first strain gauge, and a third pad and a fourth pad are provided at the position of the second strain gauge. The first end of each of the first and third strain gauges is connected to the first pad at the corresponding position through a wire, and the second end of each of the first and third strain gauges is connected to the second pad at the corresponding position through a wire. The first end of each of the second and fourth strain gauges is connected to the third pad at the corresponding position through a wire, and the second end of each of the second and fourth strain gauges is connected to the fourth pad at the corresponding position through a wire.

6. A high torsional rigidity joint torque sensor as described in any one of claims 1 to 5, characterized in that: Both the first strain gauge and the second strain gauge are silicon strain gauges, which are fixedly mounted on the thin-walled strain beam using a glass micro-melting sintering process.

7. A high torsional rigidity joint torque sensor as described in claim 6, characterized in that: The first and second strain gauges of each front strain gauge pair are symmetrically arranged, and the axis of symmetry of the first and second strain gauges passes through the center of the inner flange; the angle between the axis of the first strain gauge and the axis of the second strain gauge and the axis of symmetry is 45°.

8. A high torsional rigidity joint torque sensor as described in claim 7, characterized in that: The thickness of the thin-walled strain beam is determined by simulation software based on the strain magnitude requirements of the torque sensor; the first strain gauge and the second strain gauge are set in the region of maximum strain of the thin-walled strain beam, and the region of maximum strain of the thin-walled strain beam is determined by the simulation results of finite element simulation software.

9. A high torsional rigidity joint torque sensor as described in any one of claims 1 to 5, characterized in that: The torque sensor flange is made of rigid material; the inner flange has a through hole in the middle, and multiple inner flange threaded holes are provided around the through hole in the circumferential direction; a raised ring is provided on the back of the inner flange corresponding to the periphery of the multiple inner flange threaded holes; multiple outer flange threaded holes are provided on the outer flange in the circumferential direction.

10. A high torsional rigidity joint torque sensor as described in any one of claims 1 to 5, characterized in that: The torque sensor includes two strain gauge groups, namely a first strain gauge group and a second strain gauge group. The spacing between each front strain gauge pair in the first strain gauge group and the adjacent front strain gauge pair in the second strain gauge group is equal.

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