Flexible tension sensor and preparation method thereof

Abstract

The invention relates to a flexible tension sensor and a preparation method thereof, and belongs to the field of Internet of Things. An existing tension sensor has the problems of insufficient precision, large temperature influence, poor stability, complex installation, high cost, delayed data processing and the like. The sensor comprises two hollow pipes (a thin pipe and a thick pipe) made of elastic materials, wherein the thin pipe is nested in the thick pipe; the linear RFID antenna is fixed in the thin tube, the spiral RFID antenna is wound on the outer surface of the thick tube through a yarn covering process, and the linear RFID antenna and the spiral RFID antenna form a differential antenna structure. The preparation method comprises the steps of manufacturing the linear RFID antenna, preparing the hollow tube, assembling the hollow tube, manufacturing the spiral RFID antenna, reading an RSSI value and the like. The method has the advantages that the precision is high, and the method can be used for micro-force measurement; materials influenced by temperature are not contained, and the measurement result is stable; the structure is simple, cost is low and installation is convenient; and the data processing real-time performance is high.

Description

Technical Field

[0001] The present invention relates to the field of the Internet of Things, and more specifically, it relates to a flexible tensile sensor and a preparation method thereof. Background Art

[0002] As an important device for measuring force and weight, tensile sensors have a wide range of applications in many fields such as industrial production, automation control, and medical equipment. However, there are still some deficiencies and defects in the technical implementation and application process of current tensile sensors on the market. The main manifestations are as follows: 1. Accuracy problem: Although modern tensile sensors have made significant improvements in accuracy, in high-precision measurement scenarios, especially in the measurement of small forces or dynamic forces, the accuracy of the sensors may still be insufficient.

[0003] 2. Temperature influence: The output signal of the tensile sensor may be affected by the ambient temperature, resulting in temperature drift. In an environment with large temperature changes, the output signal of the sensor may shift, affecting the measurement accuracy.

[0004] 3. Long-term stability problem: During long-term use of the tensile sensor, problems such as mechanical fatigue and performance degradation of the strain gauges inside the sensor may occur, resulting in a decrease in the long-term stability of the sensor. In scenarios that require long-term continuous operation, the performance degradation of the sensor may lead to inaccurate measurement results, affecting the normal operation of the equipment.

[0005] 4. Installation complexity: The installation process of some tensile sensors is relatively complex and requires precise alignment and adjustment. Otherwise, it may affect the measurement accuracy. In addition, the mechanical structure design of the sensor may not be compact enough, resulting in limited installation space. During the equipment integration and installation process, the complex installation steps may increase the operation difficulty and time cost, affecting the overall efficiency of the equipment.

[0006] 5. Cost issue: High-precision and high-stability tensile sensors usually have a high price, and for some application scenarios with limited budgets, the cost may become a restrictive factor.

[0007] 6. Data processing and transmission delay: The signal processing and data transmission speed of some tensile sensors are relatively slow. Especially in high-frequency measurement or scenarios that require real-time feedback, the data transmission delay may cause the control system to respond untimely. In applications that require real-time control and feedback, the data transmission delay may cause the control system to be unable to adjust in time, affecting the operation efficiency and accuracy of the equipment.

[0008] In summary, there are still some deficiencies in the accuracy and stability, anti-interference ability, dynamic response, environmental adaptability, etc. of tensile sensors, and these defects may have a negative impact on the performance and reliability of equipment in different application scenarios. Summary of the Invention

[0009] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a tensile sensor with a simple structure and good performance.

[0010] To achieve the above object, the present invention provides the following technical solutions: A flexible tensile sensor includes two hollow tubes, a linear RFID antenna and a helical RFID antenna. The two hollow tubes are a thin tube and a thick tube respectively, and the thin tube is nested inside the thick tube; the linear RFID antenna is fixed inside the thin tube; the helical RFID antenna is wound around the outer surface of the thick tube by a wrapping yarn process and forms a differential antenna structure with the linear RFID antenna.

[0011] Further, both the linear RFID antenna and the helical RFID antenna are composed of a tag chip and two enameled copper wires.

[0012] Further, both of the two hollow tubes are made of elastic materials.

[0013] Further, the helical RFID antenna is fixed on the thick tube through a yarn, and the yarn is spirally wound around the thick tube.

[0014] A preparation method of a flexible tensile sensor, characterized by including steps S1. Fabricate two linear RFID antennas; S2. Prepare two hollow tubes with different diameter sizes; S3. Fix one linear RFID antenna inside a hollow tube with a smaller diameter size, and then place this hollow tube inside a hollow tube with a larger diameter size; S4. Wind and fix the other linear RFID antenna on the outer surface of the hollow tube with a larger diameter size to form a helical RFID antenna; S5. Use a reader to read the RSSI value of the antenna to achieve tensile force measurement.

[0015] Further, in step S1, when preparing the linear RFID antenna, it includes steps: a. Prepare a tag chip and two enameled copper wires; b. Remove the enamel of one end of each enameled wire and reserve a welding section; c. After fixing the tag chip, place the enameled wire removed part at the corresponding position on the tag chip and perform low-temperature solder paste dotting; d. Use a hot air gun to heat the tag chip pads and form solder joints; e. Use black glue and / or resin to coat and protect the chip; f. First, use the dipole antenna calculation formula to calculate the length of the antenna, and then use an anechoic chamber to finely adjust the size to determine the optimal antenna length.

[0016] Further, in step S4, a wrapping machine is used to interweave a plurality of forward yarns and a plurality of reverse yarns to form a spiral structure; and a straight RFID antenna is used to replace one of the yarns to form a spiral structure.

[0017] By adopting the above technical solutions, the beneficial effects of the present invention are as follows: Accuracy: The sensor of the present invention utilizes the deformation of the structure and the coupling between structures to cause changes in RSSI. When the pitch of the second tag is small, even a slight change will have an obvious impact on RSSI. Therefore, it can be used for measuring relatively small forces.

[0018] Temperature: The structure of the sensor of the present invention does not contain materials affected by temperature. Therefore, when the temperature changes, it will not have an obvious impact on the measurement results.

[0019] Stability: The structure of the sensor of the present invention adopts a sleeve assembly method. The tag is located inside the thin tube. When the structure is subjected to tensile force, there is a gap between the tubes. Even if the thick tube deforms, it will not affect the thin tube, and the thin tube can well protect the tag from being damaged. In addition, for the tag, it is a spiral structure and the interwoven yarns can also firmly fix it on the surface of the thick tube. When the structure expands and contracts, the tag also deforms accordingly. Due to the special structure, even after multiple stretches, the performance of the tag will not decay. Therefore, this structure is relatively stable in terms of performance.

[0020] Cost and installation structure: The structure of the sensor of the present invention is simple, only requiring 2 ordinary RFID tags to achieve, and it has the characteristics of small size, flexibility, fatigue resistance, etc. It is also convenient to carry and use, and the cost is low.

[0021] Data processing: A reader antenna is used to read the RSSI value of the structure. For the data, it has real-time performance, that is, the structure stretching and data reading are synchronized. When the structure changes, the measured RSSI also changes. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the preparation process of the straight RFID tag in the present invention.

[0023] Figure 2 It is a schematic diagram of the structure of the sensor of the present invention.

[0024] Figure 3 It is a graph showing the change law of the RSSI value of the sensor in Example 1.

[0025] Figure 4 Variation pattern diagram of the RSSI value of the sensor in Embodiment 2 Specific implementation mode

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is 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 should not be construed as a limitation of the present invention.

[0028] The flexible tensile sensor includes two hollow tubes, a linear RFID antenna 3 and a helical RFID antenna 4. The two hollow tubes are respectively a thin tube 1 and a thick tube 2, wherein the thin tube 1 is nested inside the thick tube 2; the linear RFID antenna 3 is fixed inside the thin tube 1; the helical RFID antenna 4 is wound on the outer surface of the thick tube 2 through a covering yarn process and forms a differential antenna structure with the linear RFID antenna 3. The specific preparation process is as follows: As Figure 1 shown, Step 1, prepare two linear RFID tags, and the specific preparation process of the tags is as follows: ① Prepare the used tag chips and two enameled copper wires with a diameter of 80um.

[0029] ② Remove the enamel from one end of each enameled copper wire and reserve an appropriate length.

[0030] ③ After fixing the chip, place the enameled part of the copper wire in a suitable position and perform low-temperature solder paste dotting.

[0031] ④ Use a hot air gun to heat the chip pads and form a firm solder joint.

[0032] ⑤ Protect the chip with black glue and resin.

[0033] ⑥ First, use the common dipole antenna calculation formula to calculate the length of the antenna, and then use the anechoic chamber produced by Voyantic Company to finely adjust the size to determine the optimal antenna length.

[0034] Step 2: Prepare two hollow tubes of different sizes (the specific sizes and elastic properties of the tubes can be changed according to actual requirements).

[0035] Step 3: Place a straight RFID antenna 3 inside the thin tube 1, and then place the thin tube 1 inside the thick tube 2.

[0036] Step 4: Use a 12 - thread wrapping machine (the wrapping machine can be selected according to your own needs), with 6 forward yarns and 6 reverse yarns intertwined with each other.

[0037] Step 5: Replace any one of the wrapping yarns with another straight RFID antenna to prepare a helical RFID antenna. By adjusting the parameters of the wrapping machine, such as rotational speed, traction force, pitch, etc., the pitch of the helix can be adjusted (different helix sizes can be prepared according to different requirements).

[0038] As Figure 2 shown in the schematic diagram of the sensor structure. When testing the performance of the sensor, a reader can be used to read the RSSI value of the antenna in real - time. By regularly stretching the sensor, we can monitor the change law of RSSI in real - time. When changing the initial positions between the chips, different results are obtained.

[0039] Example 1:

[0040] The result of the first initial position situation is as Figure 3 shown. When the sensor is stretched, the RSSI value of one tag shows regular changes, while the other basically remains unchanged (the slight changes are due to the influence of the test environment). By taking the difference between the two, a set of regularly changing RSSI values can be obtained, which can be used as a stretch sensor for application.

[0041] Example 2:

[0042] When changed to the second initial position, as Figure 4 shown, the measured RSSI value is a set of difference values. Compared with the first result, the second result can eliminate some unnecessary influencing factors and can better reflect the stretching change for application in tensile sensing.

[0043] The above - mentioned are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Those skilled in the art should include the usual changes and substitutions within the scope of the technical solution of the present invention within the protection scope of the present invention.

Claims

1. A flexible tension sensor, characterized in that: include Two hollow tubes, a thin tube and a thick tube, wherein the thin tube is nested inside the thick tube; A linear RFID antenna is fixed in a thin tube; The spiral RFID antenna is wound around the outer surface of the thick tube and forms a differential antenna structure with the linear RFID antenna.

2. A flexible tension sensor according to claim 1, characterized in that: The linear RFID antenna and the spiral RFID antenna are both composed of a tag chip and two enameled copper wires.

3. A flexible tension sensor according to claim 1, characterized in that: The two hollow tubes are both made of elastic material.

4. A flexible tension sensor according to claim 1, characterized in that: The spiral RFID antenna is fixed on the thick tube through the yarn, and the yarn is spirally wound on the thick tube.

5. A method for preparing a flexible tension sensor according to any one of claims 1 to 4, characterized in that: Included steps S1. Make two linear RFID antennas; S2, prepare two hollow tubes of different diameters; S3, fixing a linear RFID antenna in a hollow tube with a smaller diameter, and then placing the hollow tube in a hollow tube with a larger diameter; S4, winding and fixing another linear RFID antenna on the outer surface of the hollow tube with a larger diameter to form a spiral RFID antenna; S5. Use a reader to read the RSSI value of the antenna to measure the tension.

6. The method for preparing a flexible tension sensor according to claim 5, characterized in that: In step S1, the preparation of the linear RFID antenna includes the following steps: a. Prepare the tag chip and two enameled copper wires; b. Remove the paint from one end of each enameled wire and reserve a welding section; c. After fixing the tag chip, place the un-enamelled copper wire at the corresponding position on the tag chip and apply low-temperature solder paste; d. Use a hot air gun to heat the tag chip pad and form a solder joint; e. Use black glue and / or resin to cover and protect the chip; f. First use the dipole antenna calculation formula to calculate the length of the antenna, and then use the radio wave darkroom to fine-tune the size to determine the optimal antenna length.

7. The method for preparing a flexible tension sensor according to claim 6, characterized in that: In step S4, a yarn covering machine is used to interweave a plurality of forward yarns and a plurality of reverse yarns to form a spiral structure; and a linear RFID antenna is used to replace one of the yarns to form the spiral structure.

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