Method for accurately sensing environment change based on wireless sensing

Abstract

The invention relates to the technical field of wireless sensing, and provides a method for accurately sensing environment change based on wireless sensing, which forms a wireless sensing system in a sealed cavity by constructing a coupling structure of a pre-stretching antenna and a thin plate top cover, and thoroughly eliminates space occupation and structure damage risks brought by a traditional cable; a pressure-frequency theoretical calculation model is established, a direct mathematical relationship between environment pressure and antenna frequency points is given, non-environment interference factors are stripped by compensating initial pre-stretching deformation, and the precision limitation of traditional limited data fitting is broken through. And in combination with a dynamic monitoring mechanism, pressure change is sensed in real time, threshold alarm is triggered, and the problem of coupling interference between self deformation of the sensor and environmental deformation is solved. According to the method, high-precision acquisition of the environmental pressure is realized, empirical formula errors are remarkably reduced, and the method has excellent adaptability and reliability in aerospace high-pressure environment and moving part monitoring.

Description

Technical Field

[0001] The present invention relates to the field of wireless sensing technology, and in particular to a method for accurately sensing environmental changes based on wireless sensing. Background Art

[0002] In aviation, aerospace, and ground-based civilian applications, accurate environmental measurements, such as pressure measurement, are required. Common methods include mechanical, electrical, optical, acoustic, and chemical methods. Wired measurement is the mainstream method, with common methods including mechanical, electrical, optical, acoustic, and chemical. Wired measurement technology, as the mainstream method, is widely used in various scenarios. Meanwhile, wireless sensing technology, due to its cable-free, lightweight, and flexible advantages, has become a research hotspot, particularly in monitoring confined spaces or moving parts.

[0003] In wireless pressure measurement, existing technologies typically use fitting methods based on limited data sets. This involves experimentally acquiring a small number of data points on ambient pressure and sensor physical parameters, establishing empirical formulas, and estimating the current pressure value. Wired methods introduce operational inconvenience and risks, while wireless methods suffer from inaccuracies due to their reliance on fitting and neglect of initial conditions. These issues are particularly prominent in high-pressure scenarios such as aerospace, limiting the reliability and real-time nature of environmental change perception. Specifically:

[0004] Existing wired measurement methods require extensive cabling, significantly increasing weight and space requirements. This is particularly problematic in aviation and space launch missions, increasing system burden and impacting payload efficiency and mission feasibility. In confined spaces, wired measurement requires drilling holes for cable threading, compromising structural integrity and potentially causing leaks or safety risks, creating an insurmountable application bottleneck. In the monitoring of moving parts, cables are prone to tangling or breaking, reducing measurement flexibility and reliability, and limiting real-time monitoring capabilities. Cable-free structures are crucial for improving applicability by eliminating weight and space constraints. Existing wireless measurement methods rely on empirical fitting of limited data sets. This process is strongly influenced by the fitting model, and improper model selection can amplify errors, resulting in inaccurate pressure values. These fitting methods rely on experimental calibration and fail to consider the internal mechanical relationships of the sensor. In real-world applications, environmental changes can invalidate the fitting formula, preventing dynamic adaptation and causing measurement drift or misinterpretation. In wireless sensors, existing technologies often ignore the initial deformation caused by pre-tensioning and fail to compensate for it in the model. This results in non-environmental errors in the measured values, reducing overall accuracy. Existing technologies lack similar compensation mechanisms and are unable to distinguish between environmental pressure changes and inherent deformation, resulting in significant error accumulation, especially in long-term monitoring.

[0005] Therefore, it is of great significance to design a method based on wireless sensing to accurately perceive environmental changes to solve the above problems. Summary of the Invention

[0006] To solve the problems in the background technology, the present invention provides a method for accurately sensing environmental changes based on wireless sensing, comprising the following steps:

[0007] S1: Construct a wireless pressure sensor; create a rectangular cavity with a length, width, and height of a, n, and c, respectively, and a thin plate top cover; attach a rectangular sheet antenna to the center of the cavity bottom and the center of the top cover, respectively; seal the top cover and the cavity to form a closed cavity; embed a microchip in the antenna for data acquisition and signal transmission; and install a wireless signal receiver externally.

[0008] S2: Set the initial state parameters of the sensor; use pre-tension to make the antenna extension l1, and calculate the initial deformation of the top cover l0;

[0009] S3: Calculate the ambient pressure based on the antenna frequency change; obtain the antenna frequency value h1 in real time and calculate the ambient pressure s based on h1;

[0010] S4: Dynamic pressure monitoring; regularly monitor pressure changes and trigger an alarm signal when the pressure change exceeds the threshold.

[0011] Furthermore, in S1 , the antenna length d and the cavity length a satisfy the pre-stretching design of d=0.9a.

[0012] Furthermore, in S2, the initial deformation of the top cover l0 is calculated according to the following formula:

[0013]

[0014] Where l0 represents the initial deformation of the top cover; m represents the reference coefficient of the force at the center of the top cover; g represents the cross-sectional area of ​​the antenna; e represents the Young's modulus of the antenna; l1 represents the elongation of the antenna under pretension; p represents the Poisson's ratio of the top cover; f represents the thickness of the top cover; d represents the initial length of the antenna; and j represents the elastic modulus of the top cover.

[0015] Furthermore, the setting of l1 satisfies: l1≤0.05·l max ; Among them, l max Indicates the ultimate elongation of the antenna material.

[0016] Furthermore, in S3, the ambient pressure is calculated according to the following formula:

[0017]

[0018] Where s represents the ambient pressure; f represents the thickness of the top cover; d represents the initial length of the antenna; j represents the elastic modulus of the top cover; m represents the reference coefficient of the force at the center of the top cover; g represents the cross-sectional area of ​​the antenna; e represents the Young's modulus of the antenna; p represents the Poisson's ratio of the top cover; h0 represents the initial frequency value of the antenna; h1 represents the real-time frequency value; and n represents the reference coefficient of the uniformly distributed pressure on the top cover.

[0019] Furthermore, the calculation of the antenna initial frequency h0 in S3 is performed according to the following formula:

[0020]

[0021] Where h0 represents the initial frequency; c represents the speed of light; d represents the antenna length; and r represents the dielectric constant of the substrate.

[0022] Furthermore, the specific process of S4 includes:

[0023] Perform pressure sampling periodically and calculate the pressure change between adjacent periods Δs=s (t+1) -s (t) , if |Δs|>s th , triggering an alarm signal; where Δs represents the pressure change; s (t) Indicates the sampling pressure value of the tth cycle; s th Indicates the preset threshold.

[0024] Furthermore, ε is the strain on the antenna, and ε satisfies:

[0025]

[0026] Where ε is the antenna strain; l2 is the antenna extension after the ambient pressure changes; l1 is the antenna extension under pretension; d is the initial length of the antenna; and the ambient pressure s is calculated based on the following relationship:

[0027] h1≈h0(1-ε);

[0028] Among them, h1 is the real-time frequency value; h0 is the initial frequency value.

[0029] The beneficial effects achieved by the present invention are:

[0030] First, the present invention utilizes a coupling structure combining a pre-stretched antenna and a thin plate top cover, forming a sealed cavity after the rectangular cavity is sealed. The antenna length is designed to be a fixed ratio of the cavity length, and the pre-tension state is achieved by fixing its ends to the cavity bottom and the center of the top cover. An external wireless receiver captures the antenna's frequency shift signal in real time, eliminating the need for external power supply, eliminating the need for traditional cable routing, and avoiding the risk of structural damage caused by threading wires in confined spaces. The pre-stretching design ensures stable initial antenna tension, allowing even small deformations to be efficiently transmitted to the antenna, resolving the problem of signal drift caused by loose wireless sensors and laying the physical foundation for high-sensitivity monitoring.

[0031] Second, the present invention constructs a theoretical pressure-frequency model. Based on the principles of elastic mechanics, it establishes a mathematical relationship between top cover deformation and antenna strain, and provides a direct calculation formula for ambient pressure and antenna frequency. Based on material mechanical parameters and antenna frequency shift characteristics, the model compensates for non-environmental deformation through initial pre-stretching. This overcomes the accuracy limitations of traditional limited data fitting, realizes the physical mechanism calculation of ambient pressure, and significantly reduces the error of empirical formulas. This is especially true in extreme scenarios with high-precision requirements, such as high-pressure aerospace environments. The model can dynamically adapt to pressure changes and avoid the error accumulation problem of long-term monitoring.

[0032] Third, the present invention triggers an alarm by comparing the threshold values ​​of pressure changes in adjacent cycles, incorporates the initial top cover deformation caused by pre-stretching into the calculation system, and actively removes non-environmental interference factors in the pressure calculation, greatly improving the reliability of long-term monitoring. It can still maintain measurement accuracy in moving parts or vibrating environments, and broadens the application boundaries of wireless sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of a rectangular cavity. (A) is the front view, and (B) is the side view, showing the three-dimensional shape and single-sided open characteristics of the cavity.

[0034] Figure 2 Schematic diagram of a rectangular cover structure covering a cavity opening. (A) is a front view of the cover, and (B) is a side view of the cover, showing the thin plate structure and its dimensions.

[0035] Figure 3 Schematic diagram of a rectangular patch antenna structure, showing the antenna's geometry, natural length d, and mounted microchip.

[0036] Figure 4 This is a schematic diagram of the overall structure of the wireless pressure sensor, showing the composition of the closed cavity and the layout of the external wireless signal receiver.

[0037] Figure 5 This is a flow chart of the pressure sensing method based on wireless sensing, showing the main steps of the entire process from sensor construction to pressure monitoring. DETAILED DESCRIPTION

[0038] The technical solutions of the present invention will be described clearly and completely below in conjunction with the drawings in the present invention. In addition, the forms of the various structures described in the following embodiments are merely examples. The present invention is not limited to the various structures described in the following embodiments. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0039] Reference Figure 5 The present invention designs a method for accurately sensing environmental changes based on wireless sensing, comprising the following steps:

[0040] S1: Construct a wireless pressure sensor; make a rectangular cavity with a length, width, and height of a, b, and c, and a thin plate top cover; fix the ends of a rectangular sheet antenna to the center of the cavity bottom and the center of the top cover respectively; seal the top cover and the cavity to form a closed cavity; a microchip is built into the antenna for data acquisition and signal transmission; a wireless signal receiver is set outside; the antenna length d and the cavity length a meet the pre-stretching design of d = 0.9a.

[0041] S2: Set the initial state parameters of the sensor; use pre-tension to make the antenna extension l1, and calculate the initial deformation of the top cover l0; calculate the initial deformation of the top cover l0 according to the following formula:

[0042]

[0043] Where l0 represents the initial deformation of the top cover; m represents the reference coefficient of the force at the center of the top cover; g represents the cross-sectional area of ​​the antenna; e represents the Young's modulus of the antenna; l1 represents the elongation of the antenna under pretension; p represents the Poisson's ratio of the top cover; f represents the thickness of the top cover; d represents the initial length of the antenna; and j represents the elastic modulus of the top cover.

[0044] The setting of l1 satisfies: l1≤0.05·l max ; Among them, l max Indicates the ultimate elongation of the antenna material.

[0045] S3: Calculate the ambient pressure based on the antenna frequency change; obtain the antenna frequency value h1 in real time, and calculate the ambient pressure s based on h1; calculate the ambient pressure according to the following formula:

[0046]

[0047] Where s represents the ambient pressure; f represents the thickness of the top cover; d represents the initial length of the antenna; j represents the elastic modulus of the top cover; m represents the reference coefficient of the force at the center of the top cover; g represents the cross-sectional area of ​​the antenna; e represents the Young's modulus of the antenna; p represents the Poisson's ratio of the top cover; h0 represents the initial frequency value of the antenna; h1 represents the real-time frequency value; and n represents the reference coefficient of the uniformly distributed pressure on the top cover.

[0048] The calculation of the antenna initial frequency h0 is performed according to the following formula:

[0049]

[0050] Where h0 represents the initial frequency; c represents the speed of light; d represents the antenna length; and r represents the dielectric constant of the substrate.

[0051] ε is the strain on the antenna. For the antenna strain, ε satisfies:

[0052]

[0053] Where ε is the antenna strain; l2 is the antenna extension after the ambient pressure changes; l1 is the antenna extension under pretension; d is the initial length of the antenna; and the ambient pressure s is calculated based on the following relationship:

[0054] h1≈h0(1-ε);

[0055] Among them, h1 is the real-time frequency value; h0 is the initial frequency value.

[0056] S4: Dynamic pressure monitoring: Regularly monitor pressure changes and trigger an alarm signal when the pressure change exceeds the threshold. The specific process of S4 includes:

[0057] Perform pressure sampling periodically and calculate the pressure change between adjacent periods Δs=s (t+1) -s (t) , if |Δs|>s th , triggering an alarm signal; where Δs represents the pressure change; s (t) Indicates the sampling pressure value of the tth cycle; s th Indicates the preset threshold.

[0058] The following provides a detailed description in conjunction with embodiments.

[0059] Example 1: This example first designs and manufactures a wireless pressure sensor. Figures 1-4 , Figure 1 The rectangular cavity has only the left end open, and a cavity structure is formed in the middle. Figure 1 The open end of the rectangular shell is covered with a rectangular top cover, which is a thin plate structure, such as Figure 2 As shown in Figure 1, it can produce micro deformation under the change of environmental pressure. The wireless sensor antenna adopts a rectangular sheet structure, such asFigure 3 As shown, the natural length of the long side of the antenna is d, d=90%a, and a microchip for data acquisition, processing, signal transmission control and other functions is installed on the antenna. Figure 4 The wireless pressure sensor structure and external wireless receiver are integrated. The antenna's long ends are fixed to the center of the bottom end of the rectangular cavity and the center of the top cover, respectively, creating a suspended structure. The top cover is closed onto the cavity opening, and the interface between the top cover and the cavity is sealed to form a completely enclosed space. A wireless receiver, capable of receiving sensor signals, is placed outside the seal to obtain real-time signals transmitted by the antenna within the cavity.

[0060] The specific production process is as follows:

[0061] The first step is to make a rectangular cavity, such as Figure 1 As shown, the length, width and height of the cavity are a, b and c respectively. The cavity is not a closed space and has a surface connected to the outside world. Then, a top cover is made. The top cover is a thin plate structure, such as Figure 2 shown.

[0062] In the second step, the wireless sensor antenna adopts a rectangular sheet structure, such as Figure 3 As shown, the natural length of the long side of the antenna is d, which is slightly smaller than a. The design e=0.9a. A microchip for data acquisition, processing, and signal transmission control is installed on the antenna.

[0063] The third step is to fix the two ends of the long side of the antenna to the center of the bottom end of the rectangular cavity and the center of the top cover respectively, forming a suspended state.

[0064] The fourth step is to put the top cover on the opening of the rectangular cavity and seal the junction of the top cover and the cavity to form a completely enclosed space. A wireless receiver that can receive sensor signals is placed outside the sealing device to obtain the signal emitted by the antenna in the cavity in real time. The entire wireless pressure sensing system is completed. Figure 4 shown.

[0065] In the fifth step, after the wireless pressure sensor is manufactured, when the ambient pressure changes, the thin plate structure of the top cover undergoes micro-deformation, which causes the sheet antenna connecting the rectangular cavity and the top cover to deform, further affecting the frequency value change of the frequency point emitted by the antenna. Through the theoretical calculation method provided by the present invention, the current accurate pressure value can be obtained.

[0066] The relationship between the tension on the antenna and its own elongation is as follows: When the antenna is stretched, the stress and strain satisfy Hooke's law:

[0067] σ=e·ε (1)

[0068] Where σ is the stress on the antenna, d is the Young's modulus of the antenna, and ε is the strain on the antenna.

[0069] According to the definitions of σ and ε, we have formula (2) and formula (3):

[0070]

[0071] Among them, q i is the tension on the antenna, i=1 in the initial pre-tension state, i=2 when the external environmental pressure changes, and g is the cross-sectional area of ​​the antenna.

[0072]

[0073] Among them, l i is the extension of the antenna, i is defined as above, and d is the initial length of the antenna.

[0074] From (1), (2), and (3), we can obtain:

[0075]

[0076] Under the action of pre-tension, the initial deformation of the roof is calculated as follows:

[0077] In this embodiment, e=0.9a is set. The antenna initially has a pre-tension. The antenna is connected to the top cover, so the top cover has a slight deformation in the initial state. In order to accurately obtain the pressure value of the external environment, an accurate calculation formula is required for the deformation caused by this initial tension. Because this deformation is not introduced by the change in environmental pressure, it must be eliminated in the end.

[0078] According to the theory of elasticity, for a rectangular thin plate with four fixed sides, when the center is subjected to force q1, the maximum deflection k1 can be expressed as:

[0079]

[0080] Where m is the reference coefficient under load at the center of the roof, which is determined by the aspect ratio of the roof and can be obtained by looking up the table in the book "Theory of Plates and Shells" by S. Timoshenko and S. Woinowsky-Krieger; D is the bending stiffness of the roof, and its standard formula is:

[0081]

[0082] Where j is the elastic modulus of the top cover, f is the thickness of the top cover, and p is the Poisson's ratio of the top cover.

[0083] Under the action of pretension, the elongation of the antenna is l1, and the maximum initial deformation of the top cover l0 is the maximum deflection k1.

[0084] Formulas (4), (5), and (6) yield:

[0085]

[0086] When the external environmental pressure changes, the roof deformation is calculated as follows:

[0087] When the external pressure changes, that is, when a pressure difference occurs inside and outside the top cover, the force on the antenna will change, and further the length of the antenna will change. At this time, the elongation of the antenna is l2, and the external pressure acts evenly on the top cover, and its size is set to s.

[0088] According to the theory of elastic mechanics, for a rectangular thin plate with four fixed sides, such as a top cover, when it is subjected to a uniformly distributed force s, the maximum deflection k2 can be expressed as:

[0089]

[0090] Where n is the reference coefficient under the uniformly distributed force on the roof, which is determined by the aspect ratio of the roof and can be obtained by looking up the table in the book "Theory of plates and shells" by S. Timoshenko and S. Woinowsky-Krieger.

[0091] Substituting formula (6) into formula (8) yields:

[0092]

[0093] When the top cover deforms under a uniformly distributed force, the antenna elongation also changes. Assuming that the antenna elongation is l2 and the tension on the antenna is q2 under a uniformly distributed force s, we have:

[0094]

[0095] At this time, the deformation of the top cover center is the sum of the maximum initial deformation of the top cover l0 and the antenna extension (l2-l1), satisfying:

[0096]

[0097] The theoretical relationship between antenna frequency and pressure is as follows:

[0098] The deformation at the center of the top cover when the external environmental pressure changes is given above. At this time, the antenna will also produce strain due to its connection with the top cover, which in turn affects the frequency value of the real-time frequency point transmitted by the antenna.

[0099] The antenna strain ε can be expressed as:

[0100]

[0101] According to microstrip antenna theory, the relationship between the real-time frequency value of the antenna transmission and the antenna length is:

[0102]

[0103] Where h0 is the frequency value when the antenna has an initial length of d, c is the speed of light, and r is the relative dielectric constant of the substrate.

[0104] When the antenna strain is ε, the antenna length d1 = (1 + ε)d, and the corresponding antenna frequency value becomes h1. Substituting it into formula (13) yields:

[0105]

[0106] From (13) and (14), we can get:

[0107]

[0108] Considering that the magnitude of ε is 10 -6 , much less than 1, for Perform Taylor expansion, ignoring the high-order small terms (ε 2 and above), we can get:

[0109]

[0110] Combining (12), (15), and (16), we have:

[0111]

[0112] Therefore, as long as the real-time frequency value h1 of the current antenna is input, the accurate value s of the pressure in the current environment can be obtained.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for accurately sensing environmental changes based on wireless sensing, characterized in that: The following steps are involved: S1: Construct a wireless pressure sensor; create a rectangular cavity with length, width, and height of a, b, and c, respectively, and a thin plate top cover; attach a rectangular sheet antenna to the center of the cavity bottom and the center of the top cover, respectively; seal the top cover and the cavity to form a closed cavity; embed a microchip in the antenna for data acquisition and signal transmission; and install a wireless signal receiver externally. S2: Set the initial state parameters of the sensor; use pre-tension to make the antenna extension l1, and calculate the initial deformation of the top cover l0; S3: Calculate the ambient pressure based on the antenna frequency change; obtain the antenna frequency value h1 in real time and calculate the ambient pressure s based on h1; S4: Dynamic pressure monitoring; regularly monitor pressure changes and trigger an alarm signal when the pressure change exceeds the threshold.

2. The method according to claim 1, characterized in that In S1, the antenna length d and the cavity length a satisfy the pre-stretching design of d=0.9a.

3. The method according to claim 1, characterized in that In S2, the initial deformation of the top cover l0 is calculated according to the following formula: Where l0 represents the initial deformation of the top cover; m represents the reference coefficient of the force at the center of the top cover; g represents the cross-sectional area of ​​the antenna; e represents the Young's modulus of the antenna; l1 represents the elongation of the antenna under pretension; p represents the Poisson's ratio of the top cover; f represents the thickness of the top cover; d represents the initial length of the antenna; and j represents the elastic modulus of the top cover.

4. The method according to claim 3, characterized in that The setting of l1 satisfies: l1≤0.05·l max ; Among them, l max Indicates the ultimate elongation of the antenna material.

5. The method according to claim 1, wherein In S3, the ambient pressure is calculated according to the following formula: Where s represents the ambient pressure; f represents the thickness of the top cover; d represents the initial length of the antenna; j represents the elastic modulus of the top cover; m represents the reference coefficient of the force at the center of the top cover; g represents the cross-sectional area of ​​the antenna; e represents the Young's modulus of the antenna; p represents the Poisson's ratio of the top cover; h0 represents the initial frequency value of the antenna; h1 represents the real-time frequency value; and n represents the reference coefficient of the uniformly distributed pressure on the top cover.

6. The method according to claim 5, characterized in that The calculation of the antenna initial frequency h0 in S3 is performed according to the following formula: Where h0 represents the initial frequency; c represents the speed of light; d represents the antenna length; and r represents the dielectric constant of the substrate.

7. The method according to claim 1, characterized in that The specific process of S4 includes: Perform pressure sampling periodically and calculate the pressure change between adjacent periods Δs=s (t+1) -s (t) , if |Δs|>s th , triggering an alarm signal; where Δs represents the pressure change; s (t) Indicates the sampling pressure value of the tth cycle; s th Indicates the preset threshold.

8. The method according to claim 1, characterized in that ε is the strain on the antenna. For the antenna strain, ε satisfies: Where ε is the antenna strain; l2 is the antenna extension after the ambient pressure changes; l1 is the antenna extension under pretension; d is the initial length of the antenna; and the ambient pressure s is calculated based on the following relationship: h1≈h0(1-ε); Among them, h1 is the real-time frequency value; h0 is the initial frequency value.

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