A strain gauge for a high-precision tension and pressure sensor for robots

Abstract

The invention discloses a strain gauge of a high-precision tension and pressure sensor for a robot, comprising eight sensitive grids and five pads; four of the sensitive grids are evenly distributed on the inner circle, and the other four sensitive grids are evenly distributed on the outer circle, and the inner circle and the outer circle are concentrically arranged; on the same circle, two opposite sensitive grids form a bridge arm of a Wheatstone bridge, and the two bridge arms on the same circle are on the opposite bridge of the Wheatstone bridge, and each bridge arm is connected to a pad at both ends, wherein the ends of two adjacent bridge arms are not connected, forming a semi-enclosed full-bridge strain gauge. The nonlinearity, repeatability, measurement accuracy and anti-eccentric load capability of the tension and pressure sensor are improved.

Description

Technical Field

[0001] The invention belongs to the field of high-precision sensing and relates to a strain gauge of a high-precision tension and pressure sensor for a robot. Background Art

[0002] With the development of modern science and technology, the demand for automated and intelligent equipment such as industrial equipment, medical equipment, and humanoid robots has increased dramatically, and artificial intelligence technology has also developed rapidly. The movement of the fingers of intelligent robots or mechanical arms and the rotation of their joints are controlled by the precise measurement and feedback of high-precision tension and pressure sensors, thereby accurately controlling the movement speed and strength of the fingers and joints, and achieving the effect of autonomous completion of the movement. At the same time, to achieve flexible operation of fingers and joints, higher requirements are placed on the tension and pressure sensors to measure bending moment, torque, reaction speed, etc., and high reliability and high stability are required to ensure extremely low failure rates and long continuous operation time.

[0003] The working principle of the tension and pressure sensor is based on the strain effect, that is, when an object is subjected to an external force, it will deform, and this deformation can indirectly sense the magnitude of the force. Specifically, the core of the sensor is an elastomer, which will undergo elastic deformation when subjected to tension or pressure, and the degree of deformation is proportional to the external force. A resistance strain gauge is attached to the elastomer. When the elastomer is deformed, the resistance value of the strain gauge will change accordingly. This is based on the physical principle that the resistivity changes with the deformation of the material (called piezoresistive effect or strain effect). Usually, the strain gauge is connected in the form of a bridge circuit to more accurately measure the change in resistance value. When the resistance value of the strain gauge changes, the output voltage of the bridge circuit will change, and this change is proportional to the force applied. Finally, the weak bridge output voltage signal needs to be amplified by the signal amplifier circuit to increase the signal strength, and the stability and accuracy of the output signal are ensured through signal processing technologies such as filtering and linearization.

[0004] Tensile pressure sensors are different from liquid pressure and gas pressure measurements. Because tensile pressure is directional, the original tensile pressure sensors using circular diaphragm strain gauges have some problems. The sensor has poor anti-eccentric load performance, which causes the tensile pressure sensor to have poor nonlinearity and repeatability. Therefore, the measurement accuracy of the sensor (±1%~±0.5%) is low. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a strain gauge of a high-precision tension and pressure sensor for a robot, thereby improving the nonlinearity, repeatability, measurement accuracy and anti-eccentric load capability of the tension and pressure sensor.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A strain gauge of a high-precision tension and pressure sensor for a robot, comprising eight sensitive grids and five pads; Four sensitive grids are evenly distributed on the inner circle, and the other four sensitive grids are evenly distributed on the outer circle, and the inner circle and the outer circle are concentrically arranged; on the same circle, two opposite sensitive grids form a bridge arm of the Wheatstone bridge, and the two bridge arms on the same circle are on the opposite bridge of the Wheatstone bridge, and each bridge arm is connected to a pad at both ends, wherein the ends of two adjacent bridge arms are not connected, forming a semi-closed full-bridge strain gauge.

[0007] Preferably, the resistance values ​​of the eight sensitive grids are equal.

[0008] Preferably, the resistance values ​​of the eight sensitive grids are all 350Ω.

[0009] Preferably, the inner circle and the outer circle are respectively located in two stress concentration areas formed after the sensor is loaded.

[0010] Furthermore, the centers of the inner circle and the outer circle are located on the axes of two stress concentration areas formed after the sensor is loaded.

[0011] Preferably, the included angle between two adjacent sensitive grids on the same circle is 90°.

[0012] Preferably, one regulating gate is connected to each of two adjacent bridge arms.

[0013] Furthermore, the resistance value of each bridge arm of the Wheatstone bridge is equal.

[0014] Further, the first pad, the seventh sensitive gate, the eighth sensitive gate and the third pad form a Wheatstone bridge arm; the third pad, the third sensitive gate, the fourth sensitive gate, the first adjustment gate and the fifth pad form a Wheatstone bridge arm; the fifth pad, the fifth sensitive gate, the sixth sensitive gate, the second adjustment gate and the fourth pad form a Wheatstone bridge arm; the fourth pad, the first sensitive gate, the second sensitive gate and the second pad form a Wheatstone bridge arm; the first pad and the second pad are not short-circuited together.

[0015] Further, the fifth pad is the positive output of the Wheatstone bridge, the fourth pad is the positive excitation of the Wheatstone bridge, the third pad is the negative excitation of the Wheatstone bridge, and the first pad and the second pad are the negative output of the Wheatstone bridge.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention sets the strain gauge as 8 sensitive grids, four of which are evenly distributed on the inner circle, and the other four are evenly distributed on the outer circle. When loading is biased, the sensitive grids have a complementary effect, one side becomes larger and the other side becomes smaller, but the overall state remains basically unchanged. Secondly, the full-bridge circuit designed by the present invention has balanced resistance in each bridge arm. After being subjected to force, the change of ΔR is uniform. Therefore, the strain gauge of the present invention improves the nonlinearity, repeatability, measurement accuracy and anti-biased load capability of the tension and pressure sensor.

[0017] Furthermore, by adjusting the resistance value of the regulating grid, the initial zero point of the Wheatstone resistor is balanced, thereby achieving zero point adjustment without the need for additional compensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of a strain gauge of a high-precision tension and pressure sensor for a robot of the present invention; Figure 2 The figure is a schematic diagram of a Wheatstone bridge circuit of a strain gauge of a high-precision tension and pressure sensor for a robot according to the present invention.

[0019] Among them: 1-first pad; 2-second pad; 3-third pad; 4-fourth pad; 5-fifth pad; 6-connecting gate; N1-first sensitive gate; N2-second sensitive gate; N3-third sensitive gate; N4-fourth sensitive gate; P1-fifth sensitive gate; P2-sixth sensitive gate; P3-seventh sensitive gate; P4-eighth sensitive gate; T1-first regulating gate; T2-second regulating gate. DETAILED DESCRIPTION

[0020] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs. The terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" used in this article includes any and all combinations of one or more related listed items. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0023] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0024] like Figure 1As shown, the strain gauge of the high-precision tension and pressure sensor for the robot according to the present invention has eight sensitive grids (a first sensitive grid N1, a second sensitive grid N2, a third sensitive grid N3, a fourth sensitive grid N4, a fifth sensitive grid P1, a sixth sensitive grid P2, a seventh sensitive grid P3, and an eighth sensitive grid P4), five pads (a first pad 1, a second pad 2, a third pad 3, a fourth pad 4, and a fifth pad 5) and two adjustment grids (T1 and T2), and a semi-closed full-bridge strain gauge is formed by connecting the grid 6.

[0025] The eight sensitive grids (first sensitive grid N1, second sensitive grid N2, third sensitive grid N3, fourth sensitive grid N4, fifth sensitive grid P1, sixth sensitive grid P2, seventh sensitive grid P3, and eighth sensitive grid P4) of the strain gauge of a high-precision tension and pressure sensor for a robot described in this embodiment are used as the measuring grids of the strain gauge, and the direction of each sensitive grid is radial; the eight sensitive grids are distributed on two inner and outer circles of different diameters, named inner circle and outer circle; the inner circle and the outer circle are respectively located in two stress concentration areas formed after the sensor is loaded, and the centers of the inner circle and the outer circle are located on the axes of the two stress concentration areas formed after the sensor is loaded. Among them, four sensitive grids (first sensitive grid N1, second sensitive grid N2, third sensitive grid N3, and fourth sensitive grid N4) are evenly distributed on the inner circle, and the other four sensitive grids (fifth sensitive grid P1, sixth sensitive grid P2, seventh sensitive grid P3, and eighth sensitive grid P4) are evenly distributed on the outer circle. When the sensor is under pressure, the outer circle is under tension, and positive strain is generated at this time; the inner circle is under pressure, and negative strain is generated at this time. Four sensitive grids are evenly distributed on each circle, the angle between two adjacent sensitive grids on the same circle is 90°, and the resistance values ​​of the eight sensitive grids are equal.

[0026] The eight sensitive grids of the strain gauge of the high-precision tension and pressure sensor for a robot described in this embodiment are made equal in resistance value to 350Ω by resistance adjustment (mechanical grinding or chemical resistance adjustment).

[0027] The strain gauge of a high-precision tension and pressure sensor for a robot described in this embodiment has four sensitive grids (first sensitive grid N1, second sensitive grid N2, third sensitive grid N3, and fourth sensitive grid N4) evenly distributed on the inner circle, wherein the first sensitive grid N1 and the second sensitive grid N2 are connected in series through a connecting grid 6, and the angle between the first sensitive grid N1 and the second sensitive grid N2 is 180°, forming a bridge arm of a Wheatstone bridge; the third sensitive grid N3 and the fourth sensitive grid N4 are connected in series through a connecting grid 6, and the angle between the third sensitive grid N3 and the fourth sensitive grid N4 is 180°, also forming a bridge arm of a Wheatstone bridge; the two bridge arms on the inner circle are on the opposite bridges of the Wheatstone bridge. When the sensor is subjected to pressure load, the inner circle is subjected to pressure, and the four sensitive grids are subjected to pressure, generating negative strain.

[0028] The strain gauge of a high-precision tension and pressure sensor for a robot described in this embodiment has four sensitive grids (fifth sensitive grid P1, sixth sensitive grid P2, seventh sensitive grid P3, and eighth sensitive grid P4) evenly distributed on the outer circle, wherein the fifth sensitive grid P1 and the sixth sensitive grid P2 are connected in series through the connecting grid 6, and the angle between the fifth sensitive grid P1 and the sixth sensitive grid P2 is 180°, forming a bridge arm of the Wheatstone bridge; the seventh sensitive grid P3 and the eighth sensitive grid P4 are connected in series through the connecting grid 6, and the angle between the seventh sensitive grid P3 and the eighth sensitive grid P4 is 180°, also forming a bridge arm of the Wheatstone bridge; the two bridge arms on the outer circle are on the opposite bridges of the Wheatstone bridge. When the sensor is subjected to pressure load, the outer circle is subjected to tension, and the four sensitive grids are subjected to tension, generating positive strain.

[0029] The strain gauge of the high-precision tension and pressure sensor for a robot described in this embodiment is a non-enclosed full-bridge circuit, having five pads (first pad 1, second pad 2, third pad 3, fourth pad 4, fifth pad 5), two adjustment grids and eight sensitive grids.

[0030] Furthermore, the first pad 1, the seventh sensitive gate P3, the eighth sensitive gate P4 and the third pad 3 form a Wheatstone bridge arm.

[0031] Furthermore, the third pad 3 , the third sensitive gate N3 , the fourth sensitive gate N4 , the first regulating gate T1 and the fifth pad 5 also form a Wheatstone bridge arm.

[0032] Furthermore, the fifth pad 5 , the fifth sensitive gate P1 , the sixth sensitive gate P2 , the second regulating gate T2 and the fourth pad 4 also form a Wheatstone bridge arm.

[0033] Furthermore, the fourth pad 4, the first sensitive gate N1, the second sensitive gate N2 and the second pad 2 also form a Wheatstone bridge arm.

[0034] Furthermore, the first pad 1 and the second pad 2 are not short-circuited together, and a corresponding compensation function can be achieved.

[0035] The strain gauge of the high-precision tension and pressure sensor for a robot described in this embodiment has two adjustment grids, a first adjustment grid T1 and a second adjustment grid T2, which are arranged on both sides of the fifth pad 5. By adjusting the resistance value of the first adjustment grid T1 or the second adjustment grid T2, the initial zero point of the Wheatstone resistance is balanced.

[0036] In the strain gauge of a high-precision tension and pressure sensor for a robot described in this embodiment, the resistance value of each bridge arm of a Wheatstone bridge composed of five pads (a first pad 1, a second pad 2, a third pad 3, a fourth pad 4, and a fifth pad 5), two adjustment gates, and eight sensitive gates is equal.

[0037] Furthermore, each bridge arm of the Wheatstone bridge, including two sensitive gates, the connecting gate 6 (and the regulating gate), has a total resistance value that is equal or close to that of the other.

[0038] In summary, the present invention relates to a strain gauge of a high-precision tension and pressure sensor for a robot, which is creative. The graphic structure of the sensitive grid is not limited to the radial grid structure shown in the embodiment, and the sensitive grid resistance value of the strain gauge is not limited to 350Ω. It can be expanded to strain gauges with other complex structures such as more sensitive grid types (vertical grid and horizontal grid combined), more sensitive grid numbers, and larger (or smaller) resistance values.

[0039] The present invention relates to a strain gauge of a high-precision tension and pressure sensor for robots. Based on the existing strain gauge design technology and the new strain gauge graphic design structure developed by the present invention, a strain gauge with high-precision performance is provided to customers. The comprehensive accuracy of the manufactured sensor can reach 0.02%FS, with good linearity, good repeatability, and strong anti-eccentric load capability. It can improve the comprehensive accuracy, stability and reliability of tension and pressure sensors, diaphragm-type force sensors and various pressure sensors used in the fields of robots, mechanical arms, automation, etc. The implementation and promotion of the present invention will expand the test field and test methods of high-precision tension and pressure sensors and serve the society.

[0040] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0041] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0042] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0043] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0044] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

[0045] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this patent should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a waiver of such subject matter, nor should it be considered that the applicant has not considered such subject matter to be part of the disclosed inventive subject matter.

Claims

1. A strain gauge of a high-precision tension and pressure sensor for a robot, characterized in that: Includes eight sensitive grids and five pads; Four sensitive grids are evenly distributed on the inner circle, and the other four sensitive grids are evenly distributed on the outer circle, and the inner circle and the outer circle are concentrically arranged; on the same circle, two opposite sensitive grids form a bridge arm of the Wheatstone bridge, and the two bridge arms on the same circle are on the opposite bridge of the Wheatstone bridge, and each bridge arm is connected to a pad at both ends, wherein the ends of two adjacent bridge arms are not connected, forming a semi-closed full-bridge strain gauge.

2. The strain gauge of the high-precision tension and pressure sensor for a robot according to claim 1, characterized in that: The resistance values ​​of the eight sensitive grids are equal.

3. The strain gauge of the high-precision tension and pressure sensor for a robot according to claim 1, characterized in that: The resistance value of the eight sensitive grids is 350Ω.

4. The strain gauge of the high-precision tension and pressure sensor for a robot according to claim 1, characterized in that: The inner circle and the outer circle are respectively located in two stress concentration areas formed after the sensor is loaded.

5. The strain gauge of the high-precision tension and pressure sensor for a robot according to claim 4, characterized in that: The centers of the inner circle and the outer circle are located on the axes of the two stress concentration areas formed after the sensor is loaded.

6. The strain gauge of the high-precision tension and pressure sensor for a robot according to claim 1, characterized in that: The angle between two adjacent sensitive grids on the same circle is 90°.

7. The strain gauge of the high-precision tension and pressure sensor for a robot according to claim 1, characterized in that: Two adjacent bridge arms are respectively connected to a regulating gate.

8. The strain gauge of the high-precision tension and pressure sensor for a robot according to claim 7, characterized in that: The resistance of each arm of the Wheatstone bridge is equal.

9. The strain gauge of the high-precision tension and pressure sensor for a robot according to claim 7, characterized in that: The first pad (1), the seventh sensitive gate (P3), the eighth sensitive gate (P4) and the third pad (3) form a Wheatstone bridge arm; the third pad (3), the third sensitive gate (N3), the fourth sensitive gate (N4), the first regulating gate (T1) and the fifth pad (5) form a Wheatstone bridge arm; the fifth pad (5), the fifth sensitive gate (P1), the sixth sensitive gate (P2), the second regulating gate (T2) and the fourth pad (4) form a Wheatstone bridge arm; the fourth pad (4), the first sensitive gate (N1), the second sensitive gate (N2) and the second pad (2) form a Wheatstone bridge arm; the first pad (1) and the second pad (2) are not short-circuited together.

10. The strain gauge of the high-precision tension and pressure sensor for a robot according to claim 9, characterized in that: The fifth pad (5) is the positive output of the Wheatstone bridge, the fourth pad (4) is the positive excitation of the Wheatstone bridge, the third pad (3) is the negative excitation of the Wheatstone bridge, and the first pad (1) and the second pad (2) are the negative output of the Wheatstone bridge.

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