A method for accurately sensing environmental changes based on wireless sensing

Abstract

The application relates to the field of wireless sensing technology and provides a method for accurately sensing environmental changes based on wireless sensing, wherein a coupling structure of a pre-stretching antenna and a thin plate top cover is constructed to form a wireless sensing system in a sealed cavity, and the space occupation and structure damage risks caused by traditional cables are completely eliminated; a pressure-frequency theoretical calculation model is established, a direct mathematical relationship between environmental pressure and an antenna frequency point is given, non-environmental interference factors are removed through compensation of initial pre-stretching deformation, and the precision limitation of traditional limited data fitting is broken through. In combination with a dynamic monitoring mechanism, pressure changes are sensed in real time, and threshold alarm is triggered, and the coupling interference problem of sensor self-deformation and environmental deformation is solved. The application realizes high-precision acquisition of environmental pressure, significantly reduces the error of an empirical formula, and has excellent adaptability and reliability in aerospace high-pressure environment and motion part monitoring.

Description

Technical Field

[0001] This invention relates to the field of wireless sensing technology, and more specifically to a method for accurately sensing environmental changes based on wireless sensing. Background Technology

[0002] In the aviation, aerospace, and civilian applications, accurate measurement of environmental conditions, such as pressure measurement, is required. Common methods include mechanical, electrical, optical, acoustic, and chemical methods. Among these, wired measurement is the mainstream approach, widely used in various scenarios. Meanwhile, wireless sensing technology, due to its advantages of being cable-free, lightweight, and flexible, is gradually becoming a research hotspot, especially in monitoring confined spaces or moving parts.

[0003] In wireless pressure measurement, existing technologies typically employ fitting methods based on limited datasets. This involves experimentally acquiring a small number of data points on environmental pressure and sensor physical parameters, establishing empirical formulas, and then estimating the current pressure value. Wired methods present operational inconvenience and risks, while wireless methods suffer from insufficient accuracy due to their dependence on and neglect of initial conditions. These problems are particularly pronounced in high-pressure scenarios such as aerospace, limiting the reliability and real-time performance of environmental change sensing. Specifically:

[0004] Existing wired measurement methods require extensive cabling, significantly increasing weight and space requirements. This is particularly pronounced in aerospace launch missions, increasing system burden and impacting payload efficiency and mission feasibility. In confined spaces, wired measurements require drilling and threading, compromising structural integrity and potentially causing leaks or safety risks, creating insurmountable application bottlenecks. In monitoring moving parts, cables are prone to tangling or breakage, reducing measurement flexibility and reliability and limiting real-time monitoring capabilities. Therefore, eliminating weight and space constraints through cableless structures and improving applicability is crucial. Existing wireless measurement methods rely on empirical fitting with limited datasets. This process is heavily influenced by the fitted model; inappropriate model selection can amplify errors, leading to low pressure accuracy. The fitting method depends on experimental calibration and does not consider the internal mechanical relationships of the sensor. In practical applications, environmental changes can invalidate the fitting formula, preventing dynamic adaptation and causing measurement drift or misjudgment. In wireless sensors, existing technologies often ignore initial deformation caused by preload and fail to compensate for it in the model. This results in measurements containing errors from non-environmental factors, reducing overall accuracy. Existing technologies lack a similar compensation mechanism and cannot distinguish between changes in environmental pressure and inherent deformation, especially in long-term monitoring where errors accumulate significantly.

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

[0006] To address the problems existing 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; fabricate a rectangular cavity with length, width, and height a, n, and c respectively, and a thin plate top cover; fix a rectangular sheet antenna at both ends to the center of the bottom surface of the cavity 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; set up a wireless signal receiver externally;

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

[0009] S3: Calculate environmental pressure based on antenna frequency changes; acquire antenna frequency value h1 in real time, and calculate environmental pressure s based on h1;

[0010] S4: Dynamic pressure monitoring; periodically monitors pressure changes and triggers an alarm signal when the pressure change exceeds a threshold.

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

[0012] Furthermore, in S2, the initial deformation l0 of the top cover is calculated using 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 preload; 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 This indicates the maximum elongation of the antenna material.

[0016] Furthermore, in S3, the environmental pressure is calculated using the following formula:

[0017]

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

[0019] Furthermore, the initial frequency point h0 of the antenna in S3 is calculated 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] Pressure samples are taken periodically, and the pressure change Δs = s between adjacent periods is calculated. (t+1) -s (t) If |Δs|>s th This triggers an alarm signal; where Δs represents the pressure change; s (t) s represents the sampling pressure value in the t-th cycle; th This indicates a preset threshold.

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

[0025]

[0026] Where ε is the antenna strain; l2 is the antenna elongation after the change in environmental pressure; l1 is the antenna elongation under preload; d is the initial length of the antenna; the environmental pressure s is calculated based on the following relationship:

[0027] h1≈h0(1-ε);

[0028] Where h1 is the real-time frequency value; h0 is the initial frequency value.

[0029] The beneficial effects achieved by this invention are as follows:

[0030] First, this invention employs a coupling structure between a pre-stretched antenna and a thin-plate top cover, forming a sealed cavity after the cuboid cavity is sealed. The antenna length is designed as a fixed proportion of the cavity length, and the pre-tension state is achieved by fixing both ends to the bottom of the cavity and the center of the top cover. An externally installed wireless receiver captures the antenna frequency shift signal in real time, eliminating the need for external power supply, thus avoiding the need for traditional cable laying and the risk of structural damage caused by wiring in a confined space. The pre-stretched design ensures stable initial antenna tension, enabling minute deformations to be efficiently transmitted to the antenna, solving the signal drift problem caused by loose wireless sensors, and laying a physical foundation for high-sensitivity monitoring.

[0031] Secondly, this invention constructs a pressure-frequency theoretical model. Based on the principles of elasticity, it establishes a mathematical relationship between the deformation of the top cover and the strain of the antenna, and provides a direct calculation formula for environmental pressure and antenna frequency. Based on material mechanical parameters and antenna frequency shift characteristics, the model compensates for deformation caused by non-environmental factors through initial pre-stretching, overcoming the accuracy limitations of traditional finite data fitting. It achieves calculation of the physical mechanism of environmental pressure, significantly reducing errors in empirical formulas. Especially in extreme scenarios with high precision requirements, such as aerospace high-pressure environments, it can dynamically adapt to pressure changes, avoiding the problem of error accumulation from long-term monitoring.

[0032] Third, this invention triggers an alarm by comparing the threshold of pressure changes in adjacent cycles, incorporates the initial top cover deformation caused by pre-stretching into the calculation system, actively removes non-environmental interference factors in pressure calculation, significantly improves the reliability of long-term monitoring, and can maintain measurement accuracy even in moving parts or vibration environments, thus broadening the application boundaries of wireless sensors. Attached Figure Description

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

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

[0035] Figure 3 This is a schematic diagram of a rectangular sheet antenna structure, showing the antenna's geometry, natural length d, and the microchip installed on it.

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

[0037] Figure 5 This is a flowchart of a pressure sensing method based on wireless sensing, showing the main steps from sensor construction to pressure monitoring. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. In addition, the forms of the various structures described in the following embodiments are merely illustrative. The present invention is not limited to the structures described in the following embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

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

[0040] S1: Construct a wireless pressure sensor; fabricate a rectangular cavity with length, width, and height a, b, and c respectively, and a thin plate top cover; fix a rectangular sheet antenna at both ends to the center of the bottom surface of the cavity and the center of the top cover respectively; seal the top cover and the cavity to form a closed cavity; the antenna has a built-in microchip for data acquisition and signal transmission; set up an external wireless signal receiver; the antenna length d and the cavity length a satisfy the pre-stretch design of d = 0.9a.

[0041] S2: Set the initial state parameters of the sensor; use pre-tension to make the antenna elongation l1, and calculate the initial deformation l0 of the top cover; calculate the initial deformation l0 of the top cover 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 preload; 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 This indicates the maximum elongation of the antenna material.

[0045] S3: Calculate environmental pressure based on antenna frequency changes; acquire antenna frequency value h1 in real time, and calculate environmental pressure s based on h1; calculate environmental pressure using the following formula:

[0046]

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

[0048] The initial frequency h0 of the antenna is calculated using 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, and ε satisfies:

[0052]

[0053] Where ε is the antenna strain; l2 is the antenna elongation after the change in environmental pressure; l1 is the antenna elongation under preload; d is the initial length of the antenna; the environmental pressure s is calculated based on the following relationship:

[0054] h1≈h0(1-ε);

[0055] Where h1 is the real-time frequency value; h0 is the initial frequency value.

[0056] S4: Dynamic pressure monitoring; periodically monitors pressure changes and triggers an alarm signal when the pressure change exceeds a threshold. The specific process of S4 includes:

[0057] Pressure samples are taken periodically, and the pressure change Δs = s between adjacent periods is calculated. (t+1) -s (t) If |Δs|>s th This triggers an alarm signal; where Δs represents the pressure change; s (t) s represents the sampling pressure value in the t-th cycle; th This indicates a preset threshold.

[0058] The following detailed description is provided in conjunction with the embodiments.

[0059] Example 1: This example first involves the design and fabrication of a wireless pressure sensor, as detailed in the following section. Figures 1-4 , Figure 1 It is a rectangular cavity that is open only at the left end, with a hollow structure in the middle. Figure 1 The open end of the rectangular shell is covered by a rectangular top cover, which is a thin plate structure, such as... Figure 2 As shown, it can undergo slight deformation under changes in environmental pressure. The wireless sensor antenna adopts a rectangular sheet-like structure, such as... Figure 3 As shown, the natural length of the antenna along its long side is d, where d = 90%a. The antenna is equipped with a microchip for data acquisition, processing, and signal transmission control. Figure 4 The structure comprises a wireless pressure sensor and an external wireless receiver. The antenna's long side is fixed at the center of the bottom of a cuboid cavity and the center of the top cover, respectively, creating a suspended state. The top cover closes to the cavity opening, and the junction 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 sealed device to acquire the signals transmitted by the antenna inside the cavity in real time.

[0060] The specific production process is as follows:

[0061] The first step is to create 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 sealed space; one side is open to the outside. Next, a top cover will be fabricated. The top cover is a thin-plate structure, as shown... Figure 2 As shown.

[0062] The second step involves using a rectangular, sheet-like structure for the wireless sensor antenna, such as... Figure 3 As shown, the natural length of the antenna along its long side is d, which is slightly less than a. The design is e = 0.9a. The antenna is equipped with a microchip for data acquisition, processing, and signal transmission control.

[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 cuboid cavity and the center of the top cover, respectively, to form a suspended state.

[0064] Fourth, place the top cover onto the opening of the cuboid cavity, and seal the junction between the top cover and the cavity to create a completely sealed space. Place a wireless receiver capable of receiving sensor signals outside the sealing device to acquire the signals transmitted by the antenna inside the cavity in real time. The entire wireless pressure sensing system is then complete. Figure 4 As shown.

[0065] Fifth, after the wireless pressure sensor is manufactured, when the environmental pressure changes, the top cover thin plate structure undergoes slight deformation, which causes the sheet antenna connecting the cuboid cavity and the top cover to deform, further affecting the frequency value of the antenna's transmission frequency. The current accurate pressure value can be obtained through the theoretical calculation method given in this invention.

[0066] The relationship between the tensile force on the antenna and its elongation is as follows: Under tensile conditions, the stress and strain of the antenna 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 formulas (2) and (3):

[0070]

[0071] Where, q i Let i be the tension force on the antenna. Under the initial pre-tension state, i = 1. When the external environmental pressure changes, i = 2. g is the cross-sectional area of ​​the antenna.

[0072]

[0073] Among them, l i Let d be 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] The initial deformation of the top cover under preload is calculated as follows:

[0077] In this embodiment, e = 0.9a is set, and the antenna initially has a pre-tension force. The antenna is connected to the top cover, so the top cover initially has a slight deformation. In order to accurately obtain the pressure value of the external environment, the deformation caused by this initial tension needs to be calculated accurately, because this deformation is not introduced by the change of environmental pressure, so it must be eliminated in the end.

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

[0079]

[0080] Where m is the reference coefficient under stress at the center of the top cover, determined by the aspect ratio of the top cover, and can be obtained from the table in S. Timoshenko and S. Woinowsky-Krieger's book "Theory of Plates and Shells"; D is the bending stiffness of the top cover, 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 preload, the antenna elongation is l1, and the maximum initial deformation of the top cover, l0, is the maximum deflection, k1. Combined with the formula...

[0084] From equations (4), (5), and (6), we can obtain:

[0085]

[0086] The deformation of the roof is calculated as follows when the external environmental pressure changes:

[0087] When the external pressure changes, i.e. when a pressure difference is generated inside and outside the top cover, the force on the antenna will change, and the antenna length will change. At this time, the elongation of the antenna is l2. The external pressure is uniformly applied to the top cover, and its magnitude is s.

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

[0089]

[0090] Wherein, n is a reference coefficient under uniformly distributed force on the top cover, which is determined by the aspect ratio of the top cover and can be obtained by looking up a 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 will also change. Assuming that under a uniformly distributed force s, the antenna elongation is l2 and the tension on the antenna is q2, then:

[0094]

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

[0096]

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

[0098] The aforementioned data shows the deformation at the center of the top cover when the external environmental pressure changes. Since the antenna is connected to the top cover, it will also experience strain, which in turn affects the frequency value of the antenna's real-time transmission frequency.

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

[0100]

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

[0102]

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

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

[0105]

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

[0107]

[0108] Considering that the order of ε is in the order of 10 -6 Much less than 1, for Perform a Taylor expansion, ignoring the higher-order small terms (ε). 2 From (and above), we can obtain:

[0109]

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

[0111]

[0112] Therefore, by simply inputting the real-time frequency value h1 of the current antenna, the accurate value s of the pressure under the current environment can be obtained.

[0113] The above description is merely 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 within the protection scope of the present invention.

Claims

1. A method for accurately sensing environmental changes based on wireless sensing, characterized in that, Includes the following steps: S1: Construct a wireless pressure sensor; create a rectangular cavity with length, width, and height as follows: , , The rectangular sheet antenna is fixed at both ends to the center of the bottom surface of the cavity and the center of the top cover, respectively; the sealed top cover and the cavity form a closed cavity; the antenna has a built-in microchip for data acquisition and signal transmission; and a wireless signal receiver is set up externally. S2: Set the initial state parameters of the sensor; extend the antenna by the pre-tensioning force. Calculate the initial deformation of the top cover. ; S3: Calculate environmental pressure based on antenna frequency changes; acquire antenna frequency values ​​in real time. ,according to Calculate environmental pressure ; In S3, the environmental pressure is calculated using the following formula: ； in, Indicates environmental pressure; Indicates the thickness of the top cover; Indicates the initial length of the antenna; Indicates the elastic modulus of the top cover; Indicates the reference coefficient for the force at the center of the top cover; Indicates the cross-sectional area of ​​the antenna; This represents the Young's modulus of the antenna; Indicates the Poisson's ratio of the top cover; This indicates the initial frequency value of the antenna; Indicates the real-time frequency point value; This indicates the reference coefficient for the uniformly distributed pressure on the top cover; The initial frequency point of the antenna in S3 The calculation is performed according to the following formula: ； in, Indicates the initial frequency point; Represents the speed of light; Indicates the antenna length; Indicates the dielectric constant of the substrate; S4: Dynamic pressure monitoring; periodically monitors pressure changes and triggers an alarm signal when the pressure change exceeds a threshold.

2. The method according to claim 1, characterized in that, In S1, the antenna length With cavity length satisfy Pre-stretch design.

3. The method according to claim 1, characterized in that, In S2, the initial deformation of the top cover is calculated using the following formula. : ； in, Indicates the initial deformation of the top cover; Indicates the reference coefficient for the force at the center of the top cover; Indicates the cross-sectional area of ​​the antenna; This represents the Young's modulus of the antenna; This indicates the antenna elongation under preload; Indicates the Poisson's ratio of the top cover; Indicates the thickness of the top cover; Indicates the initial length of the antenna; This indicates the elastic modulus of the top cover.

4. The method according to claim 3, characterized in that, The The settings satisfy: ;in, This indicates the maximum elongation of the antenna material.

5. The method according to claim 1, characterized in that, The specific process of S4 includes: Pressure samples are taken periodically, and the pressure change between adjacent periods is calculated. ,like This triggers an alarm signal; among which, Indicates the change in pressure; This represents the pressure value sampled in the t-th cycle; This indicates a preset threshold.

6. The method according to claim 1, characterized in that, The strain on the antenna, the antenna strain satisfy: ； in, Antenna strain; This represents the antenna elongation after changes in environmental pressure. This refers to the antenna elongation under preload. Initial antenna length; environmental pressure The calculation is based on the following relationship: ； in, This is the real-time frequency value; This is the initial frequency value.

Images