A miniature finger force three-dimensional force sensor

Abstract

This invention discloses a miniature three-dimensional force sensor for fingers, shaped like the fingertip. It includes an elastomer, a force-receiving adapter plate, a signal processing board, an upper cover plate, and a lower cover plate. The upper cover plate is made of a soft material, and the force-receiving adapter plate is pressed into the upper cover plate and tightly adheres to its inner surface. The lower cover plate covers the lower end face of the elastomer and connects to it, while the force-receiving adapter plate is also connected to the elastomer. The signal processing board is embedded in the lower cover plate and connected to the elastomer by leads. The elastomer includes an elastomer wheel rim, a central force-receiving platform, and four strain beams. The four strain beams are evenly distributed between the central force-receiving platform and the elastomer wheel rim. Twelve single-crystal silicon semiconductor strain gauges are mounted on the four strain beams, forming three Wheatstone bridges to measure forces in the Fx, Fy, and Fz directions. Advantages: This three-dimensional force sensor is small in size, lightweight, and has high measurement resolution.

Description

Technical Field

[0001] This utility model belongs to the field of sensor measurement. Based on the principle of resistive strain, it is specifically a miniature three-dimensional force sensor for finger force, which is used in the humanoid robot industry. Background Technology

[0002] In recent years, the robotics industry has developed explosively. Due to the rapid development of humanoid robots and their use in various industries, fingertip force sensors, as a core component of the fingertips of humanoid robots, play an extremely important role.

[0003] A fingertip force sensor is a high-precision device used to measure contact force and torque during fingertip movements or fine motor operations. It is widely used in various robotics, prosthetics, medical devices, and interactive technologies to achieve accurate force feedback and tactile perception. Classified by working principle, it is mainly divided into strain gauge, piezoresistive, capacitive, and photoelectric types; from a technological perspective, it is mainly divided into two categories: MEMS sensors and biomimetic sensors. A typical application of fingertip force sensors is robot grasping, adjusting the gripping force in real time to prevent objects from slipping or being damaged. Currently, fingertip sensors face many challenges: 1) Miniaturization and multi-axis integration: Achieving high-precision multi-dimensional force (or torque) measurement within a limited space; 2) Balance between sensitivity and range: It is necessary to detect tiny forces, such as 0.1N (or even smaller), while also being able to withstand large loads; 3) Environmental interference: Temperature drift of the sensor itself caused by temperature changes, as well as electromagnetic interference, etc.; 4) The complexity of signal processing: coupling interference between multiple dimensions of sensors, and research on decoupling algorithms; 5) Breakthrough in bionics: Research on developing touch sensors that are closer to human skin.

[0004] In conclusion, fingertip force sensors are developing towards greater intelligence, flexibility, and integration, playing a central role in future humanoid robots, intelligent prosthetics, and metaverse interaction. Utility Model Content

[0005] The purpose of this invention is to propose a miniature three-dimensional force sensor for fingers, which is designed to be compatible with humanoid robots and used at the very tip of the fingers of humanoid robots, based on the needs of humanoid robot development.

[0006] The technical methods adopted are as follows: A miniature three-dimensional force sensor for finger force, the three-dimensional force sensor is shaped like the fingertip of the finger, including an elastomer, a force-receiving adapter plate, a signal processing board, an upper cover plate and a lower cover plate. The upper cover plate is made of soft material, and the force-receiving adapter plate is squeezed into the upper cover plate and tightly attached to the inner surface of the upper cover plate. The lower cover plate covers the lower end surface of the elastomer and is connected to the elastomer. The force-bearing adapter plate wraps around the upper end surface, left and right sides, and front side of the elastomer from the upper end surface downwards, and is connected to the elastomer. The outer surface of the upper cover plate is the force-bearing surface. The signal processing board is embedded in the lower cover plate and the lead wire is connected to the elastomer. The elastic body includes an elastic body rim, a central force-bearing platform, and four strain beams. The four strain beams are evenly distributed between the central force-bearing platform and the elastic body rim, with one end of each strain beam connected to the elastic body rim and the other end connected to the central force-bearing platform. A total of twelve single-crystal silicon semiconductor strain gauges are set on the four strain beams to form three Wheatstone bridges, which measure the forces in the three directions of Fx, Fy, and Fz, respectively.

[0007] In a further optimization of the technical solution of this utility model, the material of the upper cover plate is silicone rubber, and the contact surface between the upper cover plate and the load-bearing adapter plate is glued to ensure that the upper cover plate and the load-bearing adapter plate do not fall off; silicone rubber simulates human skin, making the measurement results more consistent with actual working conditions.

[0008] A further optimization of the technical solution of this utility model involves sintering a single-crystal silicon semiconductor strain gauge onto the strain beam. Considering that the elastomer of this utility model is small and cannot be bonded with a metal strain gauge, advanced glass micro-melting technology is used to sinter the single-crystal silicon semiconductor strain gauge onto the strain beam of the elastomer.

[0009] A further preferred embodiment of the present invention includes a recessed groove in the lower cover plate for accommodating the signal processing board. The signal processing board is placed within the groove and sealed with sealant. Due to the limited space, screws cannot be used for fixing; therefore, sealant is used for sealing.

[0010] Further optimization of the technical solution of this utility model: the lower cover plate is made of Peek material by 3D printing. Using Peek material for 3D printing is simple, low-cost, and lightweight, which meets the needs of the robotics industry.

[0011] A further optimization of the technical solution of this utility model is that the upper surface of the central force-bearing platform of the elastic body is 0.5mm higher than the upper surface of the elastic body rim, and the lower surface of the central force-bearing platform is 1.2mm lower than the lower surface of the elastic body rim. This provides a certain safety margin, ensuring the accuracy of the sensor's measurements in three directions.

[0012] A further optimization of the present invention involves a rectangular cross-section for the strain beams, with twelve monocrystalline silicon semiconductor strain gauges respectively disposed on the upper and lower surfaces of the four strain beams. The twelve monocrystalline silicon semiconductor strain gauges are sintered onto the upper and lower surfaces of the four strain beams on the elastomer. Due to the limitations of existing glass micro-melting technology, the monocrystalline silicon semiconductor strain gauges can only be sintered on the upper and lower surfaces of the strain beams; existing technology cannot sinter them on the sides of the strain beams.

[0013] A further optimization of the technical solution of this utility model involves sintering single-crystal silicon semiconductor strain gauges onto the upper and lower surfaces of the elastic strain beam. A specialized wire-binding machine is used to bind aluminum wires to a wire-binding plate. Corresponding solder points are provided on the wire-binding plate, and then the solder points on the wire-binding plate are bridged using terminal blocks. After bridging, the power and signal lines of each bridge are soldered to designated solder points on the signal processing board. Finally, four-core wires are led out from the designated solder points on the signal processing board. The four-core wires are led out through an outlet on the end face of the lower cover plate, and the outlet is coated with sealant. The wire-binding plates are all welded onto a shaped plate, which is integrally formed on the elastic wheel rim and located between the central force-bearing platform and the elastic wheel rim.

[0014] A further optimization of the technical solution of this utility model is that the material of the elastomer is 17-4 PH stainless steel. After a certain heat treatment process, this stainless steel material has high yield strength, which enhances the overload capacity of the sensor.

[0015] A further optimization of the technical solution of this utility model involves twelve single-crystal silicon semiconductor strain gauges, designated as R1 to R12. R1 to R4 form a full-bridge measurement of Fx, R5 to R8 form a full-bridge measurement of Fy, and R9 to R12 form a full-bridge measurement of Fz. Each bridge circuit measures one direction. The three directions of Fx, Fy, and Fz are tested using three bridge circuits respectively. Each bridge circuit is a full-bridge, and this design aims to achieve high sensitivity.

[0016] The advantages of this utility model compared with the prior art are as follows: 1. The miniature three-dimensional force sensor of this invention is used for the fingertip of a humanoid robot. It has a total length of 31mm, a width of 18mm, and a thickness of 15.35mm. It is a three-dimensional force sensor with a small size. 2. The miniature three-dimensional force sensor of this utility model has a larger force-receiving area (specifically: the upper end of the elastic body wraps around the upper end surface, left and right sides and front side of the elastic body from the upper end surface downward), almost covering the fingertip at the very tip of the finger, and the force-receiving adapter plate of the sensor is directly fixed on the central force-receiving platform of the elastic body, so the measurement results are more accurate. 3. The miniature finger force three-dimensional force sensor of this utility model uses an elastomer as the sensitive component of the sensor. Due to its small size, it adopts a simple four-beam structure and uses advanced glass micro-fusion technology to sinter a single-crystal silicon semiconductor strain gauge onto the elastomer strain beam.

[0017] 4. The miniature three-dimensional force sensor of this invention uses a single-crystal silicon semiconductor strain gauge, which is 50 times more sensitive than a regular metal strain gauge. Therefore, under the same conditions, the full-scale output voltage is larger and the sensor resolution is higher. Attached Figure Description

[0018] Figure 1 This is a three-dimensional schematic diagram of the front of the three-dimensional force sensor in this embodiment; Figure 2 This is a side view of the back of the three-dimensional force sensor in this embodiment; Figure 3 This is a three-dimensional schematic diagram of an elastomer; Figure 4 It is a three-dimensional schematic diagram of an elastomer with a bracing plate; Figure 5 A schematic diagram showing the force-bearing adapter plate inserted into the upper cover plate; Figure 6 This is a front view of the elastomeric micro-melting single-crystal silicon semiconductor strain gauge in this embodiment; Figure 7 This is a schematic diagram of the bridging principle of the three-dimensional force sensor in this embodiment; Figure 8 ANSYS Workbench calculates the equivalent stress contour plot when Fx=100N is applied; Figure 9 ANSYS Workbench calculates the displacement contour plot when Fx=100N is applied; Figure 10 ANSYS Workbench calculates the equivalent stress contour plot when Fy=100N is applied; Figure 11 ANSYS Workbench calculates the displacement contour plot when Fy=100N is loaded; Figure 12 ANSYS Workbench calculates the equivalent stress contour plot when Fz=100N is applied; Figure 13 ANSYS Workbench calculates the displacement contour plot when Fz=100N is applied; Wherein, 1—upper cover plate, 11—connection hole, 12—irregular plate, 2—elastic body, 3—lower cover plate, 31—outlet, 4—force-bearing adapter plate, 5—signal processing board, 6—first strain beam, 7—second strain beam, 8—third strain beam, 9—fourth strain beam, 10—wire binding plate, R1~R12—monocrystalline silicon semiconductor strain gauges. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this utility model clearer, the following description is provided in conjunction with the appendix. Figure 1 - Appendix Figure 13 The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0020] like Figure 1 and 2 As shown, this embodiment is a miniature three-dimensional force sensor for use on the fingers of a humanoid robot. In terms of overall shape, it resembles the fingertip of a human finger. The force-receiving end of the miniature three-dimensional force sensor almost covers the fingertip, specifically by wrapping the upper surface of the elastic body downwards around the upper surface, left and right sides, and front side of the elastic body.

[0021] For example, miniature three-dimensional force sensors for finger force, as described in this embodiment, can be installed on each of the five fingers of a humanoid robot.

[0022] Because the fingertips of humanoid robots are small, the miniature three-dimensional force sensor for finger force in this embodiment is used for the fingertips of humanoid robots, with a total length of 31mm, a width of 18mm, and a thickness of 15.35mm. Figure 1 As shown.

[0023] Because the miniature finger force three-dimensional force sensor of this embodiment is small in size, a single-crystal silicon semiconductor strain gauge is used on the elastomer of the three-dimensional force sensor in this embodiment, and sintering is performed using glass micro-melting technology.

[0024] Those skilled in the art are familiar with single-crystal silicon semiconductor strain gauges and glass micro-fusion technology. Since the sensitivity of single-crystal silicon semiconductor strain gauges is 50 times that of ordinary metal strain gauges, under the same conditions, the full-scale output voltage of the three-dimensional force sensor in this embodiment is larger, and the sensor resolution is higher.

[0025] like Figure 1 As shown, a miniature three-dimensional force sensor for finger force resembles the tip of a human finger in its overall shape; it includes an elastomer 1, a force-receiving adapter plate 4, a signal processing board 5, an upper cover plate 2, and a lower cover plate 3.

[0026] Since the elastic body 1 is the core component of the three-dimensional force sensor, but because the three-dimensional force sensor is small in size, this embodiment adopts a simple four-beam structure, with each strain beam having a rectangular cross-section.

[0027] like Figure 3 As shown, the elastic body 1 includes an elastic body rim, a central force-bearing platform, and four strain beams. The cross-section of the strain beams is rectangular. The four strain beams are evenly distributed between the force-bearing platform and the elastic body rim, with one end of the strain beam connected to the elastic body rim and the other end connected to the central force-bearing platform.

[0028] A countersunk hole and a pin hole are provided on the central load-bearing platform. These two holes are used to fix the load-bearing adapter plate 4.

[0029] The lower cover plate 3 is 3D printed using Peek material. A rectangular receiving groove is provided on the lower cover plate 3. After the signal processing board 5 is welded, it is sealed in the rectangular receiving groove of the lower cover plate 3 with adhesive. The lower cover plate 3 is first glued to the elastic body rim of the elastic body 1, and then secured with two screws. Four-core wires are led out from the signal processing board 5. The configuration of the signal processing board 5 enables the three-dimensional force sensor in this embodiment to output a digital signal, such as... Figure 1 As shown, a cable outlet 31 is provided on the lower cover plate 3 for the output of four-core wires, namely a power supply: power positive and power negative; and a signal: signal positive and signal negative; the cable outlet 31 is sealed with sealant.

[0030] The force-receiving end of the miniature finger force three-dimensional force sensor in this embodiment is made of silicone rubber, which is a soft material. Therefore, a force-receiving adapter plate 4 is required to transmit the force to the elastic body 1. Specifically, the force-receiving adapter plate 4 is pressed into the upper cover plate 2 and tightly attached to the inner surface of the upper cover plate 2. A small amount of adhesive is first applied to the inner surfaces of the force-receiving adapter plate 4 and the upper cover plate 2 before the force-receiving adapter plate 4 is pressed into place. Then, the force-receiving adapter plate 4 wraps around the upper end face, left and right sides, and front side of the elastic body 1 from the upper end face downwards. Finally, a cylindrical pin and a screw are used to fasten the force-receiving adapter plate 4 to the central force-receiving platform of the elastic body 1.

[0031] In this embodiment, to simulate human skin, the upper cover plate 2 is made of silicone rubber. However, the upper cover plate 2 also serves as the force-receiving end of the three-dimensional force sensor. To solve the problem of force transmission, a force-receiving adapter plate 4 is provided. The force-receiving adapter plate 4 is pressed into the upper cover plate 2 and tightly adheres to the inner surface of the upper cover plate 2. Figure 5 As shown.

[0032] The force transmission process is as follows: When the upper cover plate 2 is subjected to a force, the upper cover plate 2 first transmits the force to the force-receiving transition plate 4, then the force-receiving transition plate 4 transmits the force to the central force-receiving platform of the elastic body 1, and finally the force-receiving platform transmits it to the strain beam. When a force is applied, strain occurs on the strain beam, and the strain is converted into voltage output by the Huisheng Bridge.

[0033] like Figure 4 As shown, the upper surface of the central force-bearing platform of elastic body 1 is 0.5mm higher than the upper surface of the elastic body wheel rim, and the lower surface of the force-bearing platform is 1.2mm lower than the lower surface of the elastic body wheel rim. This provides a certain safety space for deformation when the central force-bearing platform is subjected to load, ensuring the accuracy of sensor measurements.

[0034] like Figure 2 and 3 As shown, in this embodiment, the three-dimensional force sensor has a connection hole 11 at the rear end of the elastic body rim of the elastic body 1, which facilitates connection with the fingers of the humanoid robot.

[0035] like Figure 1 As shown, the three-dimensional force sensor in this embodiment has a small size, resulting in limited space for the strain gauge. Since ordinary metal strain gauges are too large to be attached to the strain beam using conventional adhesive, this embodiment uses a single-crystal silicon semiconductor strain gauge, sintered onto the strain beam using glass micro-fusion technology. The single-crystal silicon semiconductor strain gauge measures 1.54mm x 0.68mm (length x width).

[0036] As is known to those skilled in the art, the sensitivity coefficient of a single-crystal silicon semiconductor strain gauge is 50 times that of a conventional metal strain gauge. Therefore, under the same conditions, the full-scale output voltage of a single-crystal silicon semiconductor strain gauge is 50 times that of a conventional metal strain gauge, thus improving the resolution of the sensor.

[0037] This embodiment of the three-dimensional force sensor uses twelve single-crystal silicon semiconductor strain gauges mounted on four strain beams. The strain gauges are sintered onto the strain beams using advanced glass micro-fusion technology. As is known to those skilled in the art, given the current limitations of glass micro-fusion technology, the strain gauges can only be sintered on the upper and lower surfaces of the strain beams, not on the sides. Based on relevant principles in materials mechanics, these twelve strain gauges are arranged into three Wheatstone bridges to measure forces in the Fx, Fy, and Fz directions, thus ensuring structural decoupling in these three directions.

[0038] In this embodiment, the single-crystal silicon semiconductor strain gauge is sintered on the strain beam of the elastic body 1. After sintering, a professional wire bonding machine is used to bond the leads of the single-crystal silicon semiconductor strain gauge to the wire bonding board. Corresponding solder points are provided on the wire bonding board. Then, the terminals are used to bridge the wires on the wire bonding board. After the bridge is completed, the power lines and signal lines of the three bridge circuits are soldered to the corresponding solder points on the signal processing board 5. Finally, four core wires are led out from the designated solder points on the signal processing board 5, namely: power positive and power negative, signal positive and signal negative.

[0039] like Figure 3 As shown, two binding plates 10 are embedded in the elastic body 1 and cover the four strain beams, located on the upper and lower sides of the elastic body 1; both binding plates 10 are welded to the irregular plate 12, which is integrally formed on the elastic body wheel rim and located between the central force-bearing platform and the elastic body wheel rim.

[0040] In this embodiment, the material of the elastomer 1 is stainless steel. The stainless steel material selected in this embodiment is 17-4 PH. After a certain heat treatment process, this stainless steel material has high yield strength, which enhances the overload capacity of the sensor.

[0041] like Figure 3 As shown, four strain beams are symmetrically arranged on the elastic body 1, namely the first strain beam 6, the second strain beam 7, the third strain beam 8, and the fourth strain beam 9.

[0042] like Figure 6 As shown, twelve single-crystal silicon semiconductor strain gauges are sintered onto the strain beams of the elastic body 1 using advanced glass micro-fusion technology. As mentioned earlier, based on the current level of glass micro-fusion technology, they can only be sintered onto the upper and lower surfaces of the four strain beams to form three Wheatstone bridges, which measure the forces in the three directions of Fx, Fy, and Fz respectively.

[0043] like Figure 6 and 7 As shown, the three-dimensional force sensor in this embodiment employs a full-bridge measurement scheme for the three measurement directions Fx, Fy, and Fz. Bridge circuit one measures Fx, bridge circuit two measures Fy, and bridge circuit three measures Fz. Twelve single-crystal silicon semiconductor strain gauges are designated R1~R12, where R1~R4 form the full-bridge measurement for Fx, R5~R8 form the full-bridge measurement for Fy, and R9~R12 form the full-bridge measurement for Fz.

[0044] The three-dimensional force sensor in this embodiment has a range of Fx=Fy=Fz=100N.

[0045] In this embodiment, the twelve single-crystal silicon semiconductor strain gauges of the miniature finger force three-dimensional force sensor are attached in the following positions: like Figure 6As shown, in this embodiment, the micro-melting positions of the twelve single-crystal silicon semiconductor strain gauges in the three-dimensional force sensor are as follows: Figure 3 As shown, four strain beams are defined as the first strain beam 6, the second strain beam 7, the third strain beam 8, and the fourth strain beam 9. The first strain beam 6 and the second strain beam 7 are placed on the X-axis, and the third strain beam 8 and the fourth strain beam 9 are placed on the Y-axis.

[0046] When Fx is applied, the first strain beam 6 undergoes tensile deformation, and the second strain beam 7 undergoes compressive deformation. Fx is measured by a Wheatstone bridge composed of R1 to R4. According to ANSYS Workbench calculations, R1 is sintered on the upper surface of the first strain beam 6, and R4 is sintered on the lower surface of the first strain beam 6; R2 is sintered on the upper surface of the second strain beam 7, and R3 is sintered on the lower surface of the second strain beam 7; R1, R2, R3, and R4 are micro-melted close to the central force-bearing platform of the elastic body 1.

[0047] When Fy is applied, the fourth strain beam 9 undergoes tensile deformation, and the third strain beam 8 undergoes compressive deformation. Fy is measured by a Wheatstone bridge composed of R5 to R8. According to ANSYS Workbench calculations, R5 is sintered on the upper surface of the fourth strain beam 9, and R8 is sintered on the lower surface of the fourth strain beam 9; R6 is sintered on the upper surface of the third strain beam 8, and R7 is sintered on the lower surface of the strain beam 8; similarly, R5, R6, R7, and R8 are micro-melted close to the central force-bearing platform of the elastic body 1.

[0048] When Fz is applied, strain beams 6, 7, 8, and 9 all undergo bending deformation. Fy is measured using a Wheatstone bridge composed of R9 to R12. ANSYS Workbench calculations show that R9 is sintered on the upper surface of strain beam 6, R10 on the lower surface, R12 on the upper surface of strain beam 7, and R11 on the lower surface. R9, R10, R11, and R12 are micro-melted close to the rim of elastic body 1.

[0049] like Figure 6 As shown, R1 and R9, located on the upper surface of the first strain beam 6, are symmetrically arranged about the axis of the first strain beam 6; similarly, R4 and R10 are also symmetrically arranged about the axis of the first strain beam 6. R2 and R12, located on the upper surface of the second strain beam 7, are symmetrically arranged about the axis of the second strain beam 7; similarly, R3 and R11 are also symmetrically arranged about the axis of the second strain beam 7.

[0050] The strength analysis process of elastic body 1 in this embodiment using ANSYS Workbench is as follows: As mentioned earlier, a measurement scheme using three Wheatstone bridges was employed for the three measurement directions Fx, Fy, and Fz. Simulation calculations were performed in ANSYS Workbench, with each direction subjected to full-scale loading individually. The strength and output sensitivity under full-scale loading were calculated for each direction, using 17-4PH stainless steel as the material. In the following calculations of the sensitivity of each bridge circuit, the bridge excitation voltage is assumed to be 10V.

[0051] When loading Fx=100N; such as Figure 8 and 9 As shown; The first strain beam 6 undergoes tensile deformation, and the second strain beam 7 undergoes compressive deformation, such as Figure 6 and 7 As shown, R1 is sintered on the upper surface of the first strain beam 6, R4 is sintered on the lower surface of the first strain beam 6, R2 is sintered on the upper surface of the second strain beam 7, and R3 is sintered on the lower surface of the second strain beam 7. R1 and R4 are subjected to tensile strain, while R2 and R3 are subjected to compressive strain. The composition is as follows: Figure 7 Bridge 1 in the middle, calculated by ANSYS Workbench, has an equivalent stress of 80.46 MPa and a deformation of 0.0038485 mm. The strain measured by R1 is... The dependent variable measured by R² is The dependent variable measured by R3 is The dependent variable measured by R4 is ,but: , —This indicates the output voltage value in the Fx direction when Fx is fully loaded; — This represents the sensitivity coefficient of a single-crystal silicon semiconductor strain gauge. In calculations, the average value is usually taken, with k=50. —This represents the strain measured at the R1 patch area of ​​the strain gauge; —This represents the strain measured in the R2 patch area of ​​the strain gauge; —This represents the strain measured in the R3 patch area of ​​the strain gauge; —This represents the strain measured at the R4 patch area of ​​strain gauge; —This represents the excitation voltage of the bridge circuit, which is taken here.

[0052]

[0053] Then the output sensitivity in the Fx direction:

[0054] When loading Fy=100N, such as Figure 10 and 11 As shown; The fourth strain beam 9 undergoes tensile deformation, while the third strain beam 8 undergoes compressive deformation, such as... Figure 6 and 7 As shown, R5 is sintered on the upper surface of the fourth strain beam 9, R8 is sintered on the lower surface of the fourth strain beam 9, R6 is sintered on the upper surface of the third strain beam 8, and R7 is sintered on the lower surface of the third strain beam 8. R5 and R8 are subjected to tensile strain, while R6 and R7 are subjected to compressive strain. The composition is as follows: Figure 7 Bridge section 2, calculated using ANSYS Workbench, has an equivalent stress of 31.715 MPa and a deformation of 0.00069578 mm. The strain measured by R5 is... The dependent variable measured by R6 is The dependent variable measured by R7 is The dependent variable measured by R8 is ,but: , —This indicates the output voltage value in the Fy direction when Fy is fully loaded; — This represents the sensitivity coefficient of a single-crystal silicon semiconductor strain gauge. In calculations, the average value is usually taken, with k=50. —This represents the strain measured in the R5 patch area of ​​the strain gauge; —This represents the strain measured in the R6 patch area of ​​the strain gauge; —This represents the strain measured in the R7 patch area of ​​the strain gauge; —This represents the strain measured in the R8 patch area of ​​the strain gauge; —This represents the excitation voltage of the bridge circuit, which is taken here.

[0055] The output sensitivity in the Fy direction is: The sensitivity is: , When loading Fz=100N, such as Figure 12 and 13 As shown; The first strain beam 6, the second strain beam 7, the third strain beam 8, and the fourth strain beam 9 all underwent bending deformation, such as Figure 6 and 7As shown, R9 is sintered on the upper surface of the first strain beam 6, R10 is sintered on the lower surface of the first strain beam 6, R12 is sintered on the upper surface of the second strain beam 7, and R11 is sintered on the lower surface of the second strain beam 7. R9 and R12 are subjected to positive strain, while R10 and R11 are subjected to negative strain. The composition is as follows: Figure 7 Bridge 3 in the middle, calculated by ANSYS Workbench, has an equivalent stress of 105.16 MPa and a deformation of 0.023462 mm. The strain measured by R9 is... The dependent variable measured by R10 is The dependent variable measured by R11 is The dependent variable measured by R12 is ,but: , —This indicates the output voltage value in the Fz direction when Fz is fully loaded; — This represents the sensitivity coefficient of a single-crystal silicon semiconductor strain gauge. In calculations, the average value is usually taken, with k=50. —This represents the strain measured in the R9 patch area of ​​the strain gauge; —This represents the strain measured in the R10 patch area of ​​the strain gauge; —This represents the strain measured in the R11 patch area of ​​the strain gauge; —This represents the strain measured in the R12 patch area of ​​the strain gauge; —This represents the excitation voltage of the bridge circuit, which is taken here.

[0056] The output sensitivity in the Fz direction is: The sensitivity is: .

[0057] The miniature finger force three-dimensional force sensor in this embodiment, after modal analysis of the elastomer using ANSYS Workbench, has a natural frequency of 12845Hz and exhibits good dynamic performance.

[0058] The miniature finger force three-dimensional force sensor in this embodiment, as determined by modal analysis, is small in size, lightweight, and has high measurement resolution.

[0059] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A miniature three-dimensional force sensor for finger force, characterized in that, The three-dimensional force sensor is shaped like the fingertip at the very front of a finger, including an elastomer (1), a force-receiving adapter plate (4), a signal processing board (5), an upper cover plate (2), and a lower cover plate (3). The upper cover plate (2) is made of soft material, and the force-receiving adapter plate (4) is squeezed into the upper cover plate (2) and is in close contact with the inner surface of the upper cover plate (2). The lower cover plate (3) covers the lower end surface of the elastomer (1) and is connected to the elastomer (1). The force-bearing adapter plate (4) wraps around the upper end surface, left and right sides and front side of the elastomer (1) from the upper end surface and is connected to the elastomer. The outer surface of the upper cover plate (2) is the force-bearing surface. The signal processing board (5) is embedded in the lower cover plate (3) and the lead wire is connected to the elastomer (1). The elastic body (1) includes an elastic body rim, a central force-bearing platform, and four strain beams. The four strain beams are evenly distributed between the central force-bearing platform and the elastic body rim, and one end of each strain beam is connected to the elastic body rim, and the other end is connected to the central force-bearing platform. A total of twelve single-crystal silicon semiconductor strain gauges are set on the four strain beams to form three Wheatstone bridges to measure the forces in the three directions of Fx, Fy, and Fz.

2. The miniature finger force three-dimensional force sensor according to claim 1, characterized in that, The material of the top cover plate (2) is silicone rubber, and the contact surface between the top cover plate (2) and the load-bearing adapter plate (4) is glued together.

3. The miniature finger force three-dimensional force sensor according to claim 1, characterized in that, A single-crystal silicon semiconductor strain gauge is sintered onto a strain beam.

4. The miniature finger force three-dimensional force sensor according to claim 1, characterized in that, The lower cover plate (3) is recessed to accommodate the signal processing board (5), and the signal processing board (5) is placed in the accommodating groove and sealed with sealant.

5. The miniature finger force three-dimensional force sensor according to claim 1, characterized in that, The lower cover plate (3) is made by 3D printing using Peek material.

6. The miniature finger force three-dimensional force sensor according to claim 1, characterized in that, The upper surface of the center force-bearing platform of the elastomer (1) is 0.5 mm higher than the upper surface of the elastomer wheel rim, and the lower surface of the center force-bearing platform is 1.2 mm lower than the lower surface of the elastomer wheel rim.

7. The miniature finger force three-dimensional force sensor according to claim 1, characterized in that, The cross-section of the strain beam is rectangular, and twelve single-crystal silicon semiconductor strain gauges are respectively set on the upper and lower surfaces of the four strain beams.

8. The miniature finger force three-dimensional force sensor according to claim 7, characterized in that, The single-crystal silicon semiconductor strain gauge is sintered on the upper and lower surfaces of the strain beam of the elastic body (1). The aluminum wire is tied to the binding plate using a professional wire binding machine. Corresponding solder points are provided on the binding plate. Then, the solder points on the binding plate are bridged with terminal blocks. After bridging, the power lines and signal lines of each bridge are soldered to the designated solder points on the signal processing board (5). Finally, four-core wires are led out from the designated solder points on the signal processing board (5). The four-core wires are led out through the outlet (31) opened on the end face of the lower cover plate (3). The outlet (31) is coated with sealant. The binding plates are all soldered on the shaped plate (12). The shaped plate (12) is integrally formed on the elastic body wheel rim and is located between the central force-bearing platform and the elastic body wheel rim.

9. The miniature finger force three-dimensional force sensor according to claim 7, characterized in that, The material of the elastomer (1) is 17-4 PH stainless steel.

10. The miniature finger force three-dimensional force sensor according to claim 7, characterized in that, The twelve single-crystal silicon semiconductor strain gauges are R1~R12, of which R1~R4 form a full-bridge measurement Fx, R5~R8 form a full-bridge measurement Fy, and R9~R12 form a full-bridge measurement Fz.

Images