Method for guaranteeing low power consumption and data reliability of inspection well monitoring terminal based on edge calculation

Abstract

The invention relates to the technical field of signal transmission, and discloses an inspection well monitoring terminal low power consumption and data reliability guarantee method based on edge calculation, which comprises the following steps: collecting well lid vibration signals through a terminal built-in sensor, and extracting vibration dominant frequency, amplitude and instantaneous phase; constructing a well lid edge gap opening model reflecting the contact state of the well lid and the well seat by using the vibration amplitude, and deducing an effective electromagnetic transmission window proportion in combination with a preset radio frequency signal overflow threshold; calculating the number of retransmission times of the data packets meeting the transmission success probability according to the proportion, and calculating the optimal emission moment offset aiming at the maximum gap opening according to the vibration phase; and finally generating a discrete emission time sequence set and driving a radio frequency unit to send data. According to the invention, a micro gap generated by structural vibration is used as an electromagnetic transmission channel, phase-locked transmission is realized through deterministic calculation of an edge side, and the problem of communication reliability and energy efficiency balance of a low-power-consumption terminal in a strong-shielding and non-stationary channel environment is effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of signal transmission, more particularly, it relates to a method for ensuring low power consumption and data reliability of a manhole monitoring terminal based on edge computing. BACKGROUND

[0002] With the advancement of smart city construction, the demand for intelligent monitoring of urban underground pipe networks (such as drainage, water supply, gas, etc.) is increasing. Usually, monitoring terminals are installed inside inspection wells (manholes) to collect information such as water level, harmful gas concentration, and well cover status, and report data to the cloud platform through narrowband Internet of Things (NB-IoT), LoRa, and other wireless communication technologies.

[0003] In actual application scenarios, manhole monitoring terminals face extremely harsh communication environments. First, in order to meet the needs of road traffic safety and water and odor prevention, modern inspection well covers (especially ductile iron covers) are usually equipped with rubber sealing rings and closely fit with the well seat. This high-strength metal sealing structure forms an approximate Faraday cage, causing the wireless signal in the well to be severely shielded and difficult to penetrate to the ground.

[0004] Secondly, the well cover installed on the road bears the traffic load of vehicles for a long time. When a vehicle passes by, the impact load of the wheels will cause the well cover system to produce transient vibration or slight deformation. This mechanical response will cause the sealing fit of the well cover edge to change in a short time and in a pulse-like manner. This means that the physical transmission channel of the wireless signal in the well to the outside is not constantly present, but shows a high degree of dynamic change and non-stationarity with the excitation of the traffic load.

[0005] However, existing manhole monitoring terminals usually use a combination of timed wake-up and blind sending or an adaptive retransmission strategy based on signal strength indication (RSSI) when transmitting data. These traditional strategies only consider the channel as a statistically fading channel, ignoring the objective fact that the well cover structure changes dynamically with the load. Further, the terminal cannot perceive the specific time when the small gap at the edge of the well cover opens, and often attempts to send data when the well cover is in a tightly sealed state, resulting in the signal being unable to penetrate the shielding layer.

[0006] Especially when the traffic flow is low or the vehicle impact amplitude is in the critical region, the time window for the effective electromagnetic leakage gap at the edge of the well cover is extremely short. At this time, using the traditional random retransmission mechanism, the terminal is likely to repeatedly send data packets in the invalid time period, not only failing to ensure data delivery, but also causing a sharp consumption of battery power due to multiple invalid radio frequency emissions, resulting in energy waste. SUMMARY

[0007] The application provides a manhole monitoring terminal low-power consumption and data reliability guarantee method based on edge computing, which solves the technical problems proposed in the background art.

[0008] The application provides a manhole monitoring terminal low-power consumption and data reliability guarantee method based on edge computing, which includes: The acceleration sensor built-in the terminal collects the cover vibration signal, and extracts the vibration main frequency, vibration amplitude and vibration instantaneous phase from the cover vibration signal; The vibration amplitude is used to construct a cover edge gap opening model reflecting the contact state of the cover and the well seat, and the effective electromagnetic transmission window proportion is calculated based on the cover edge gap opening model and the preset radio frequency signal overflow threshold; According to the effective electromagnetic transmission window proportion and the preset communication reliability index, the data packet retransmission number meeting the transmission success probability is calculated; According to the vibration instantaneous phase and the vibration main frequency, the best transmission time offset amount aligning the maximum opening of the cover edge gap in time is calculated; Based on the best transmission time offset amount and the data packet retransmission number, a discrete transmission timing set is generated, and the radio frequency communication unit is driven to strictly perform data sending according to the discrete transmission timing set.

[0009] The application has the following advantages: 1. The application establishes a cover edge gap opening model, and accurately locks the communication transmission time at the phase point where the gap is largest due to mechanical vibration. In the working condition where the vehicle impact amplitude is small and in the critical region of signal transmission, this phase-locked sending mechanism can maximize the use of the extremely short electromagnetic leakage window, avoiding invalid radio frequency transmission in the cover sealing state, thereby significantly reducing the energy consumption required for unit data delivery, and effectively solving the problem of power consumption in the prior art in the critical scenario.

[0010] 2. The application reports the effective electromagnetic transmission window proportion and other parameters in the data, so that the cloud platform can not only obtain business data, but also perceive the structural health state and environmental sealing state of the manhole. This helps the operation and maintenance personnel to distinguish between communication failure of the device itself and shielding caused by the external environment, and provides new data support for fine operation and maintenance of the pipe network. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a flowchart of the manhole monitoring terminal low-power consumption and data reliability guarantee method based on edge computing of the application; Figure 2 is a specific implementation schematic diagram of the application. DETAILED DESCRIPTION

[0012] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0013] like Figure 1 As shown, the method for ensuring low power consumption and data reliability of manhole monitoring terminals based on edge computing includes: The vibration signal of the manhole cover is collected by the built-in accelerometer of the terminal, and the vibration main frequency, vibration amplitude and vibration instantaneous phase are extracted from it. The vibration amplitude is used to construct a manhole cover edge gap opening model that reflects the contact state between the manhole cover and the manhole seat, and the effective electromagnetic transmission window ratio is calculated based on the manhole cover edge gap opening model and a preset radio frequency signal overflow threshold. Based on the effective electromagnetic transmission window ratio and the preset communication reliability index, calculate the number of data packet retransmissions that meet the transmission success probability. Based on the instantaneous phase of the vibration and the dominant frequency of the vibration, calculate the optimal launch time offset for aligning with the maximum opening of the gap at the edge of the manhole cover in terms of time. Based on the optimal transmission time offset and the number of data packet retransmissions, a discrete transmission timing set is generated, and the radio frequency communication unit is driven to strictly follow the discrete transmission timing set to send data.

[0014] In a preferred embodiment, the vibration signal of the manhole cover is acquired by the accelerometer built into the terminal, and the vibration dominant frequency, vibration amplitude, and instantaneous phase of the vibration are extracted from it, including: By number of sampling points and sampling rate Acquire acceleration data sequence Calculate its spectrum : ; Extracting the index of the largest spectral peak And calculate the dominant frequency of the vibration. : ; Calculate the vibration amplitude : ; Using Hilbert transform Constructing analytic signals And extract the instantaneous phase of the vibration. : ; in, The imaginary unit, For discrete-time indexing, For discrete frequency indexes.

[0015] Preferably, the manhole monitoring terminal has a built-in acceleration sensor to collect vibration signals generated by the manhole cover under vehicle load, so as to extract the vibration main frequency, vibration amplitude and vibration instantaneous phase. These parameters will serve as the basic input for the subsequent construction of the micro-crack model of the manhole cover edge.

[0016] First, the terminal selects the preset number of sampling points. and sampling rate Acquire acceleration data sequence ,in This is a discrete-time index, with a value range of [value range missing]. to ; The preferred value is 200. The preferred value is 100Hz. The main vibration frequency of the manhole cover when excited by vehicle load is usually in the range of 20Hz to 50Hz. The sampling rate of 100Hz satisfies the Nyquist sampling theorem, and 200 sampling points can guarantee the resolution of spectrum calculation.

[0017] Based on the acquired acceleration data sequence Calculate its spectrum The corresponding calculation formula is: ; in This is a discrete frequency index, with a value range of [value range missing]. to , The imaginary unit is used in this formula, which is the standard form of the Discrete Fourier Transform to convert vibration signals in the time domain to the frequency domain in order to extract the dominant frequency characteristics of the vibration.

[0018] After obtaining the spectrum Then, extract the index corresponding to the largest spectral peak. The corresponding determination method is as follows: ; Specifically, the frequency component with the most concentrated energy in the vibration signal corresponds to the main vibration frequency of the manhole cover after excitation. Therefore, by finding... The index corresponding to the maximum value can determine the location of the principal vibration frequency; based on Calculate the dominant frequency of vibration The corresponding calculation formula is: ; in, It is the dominant frequency of the manhole cover vibration, and its value is determined by... , and A joint decision.

[0019] Then the vibration amplitude was calculated. The corresponding calculation formula is: ; Specifically, the intensity of the vibration signal is characterized by calculating the root mean square value of the acceleration data sequence. The meaning is the root mean square amplitude of the vibration signal, and its value reflects the intensity of the vehicle load excitation.

[0020] Then use Hilbert transform Constructing analytic signals The corresponding construction method is: ; Specifically, analytic signals can be used to extract the instantaneous phase features of a signal, while the Hilbert transform generates signals that are analogous to or analogous to the instantaneous phase features of the signal. Orthogonal components thus constitute a complex-valued analytic signal; Based on constructed analytic signals Extracting the instantaneous phase of vibration The corresponding calculation formula is: ; in The calculated dominant vibration frequency can be used to obtain the phase of the vibration signal on the dominant frequency component, i.e., the instantaneous phase, by multiplying the analytical signal with the complex exponential signal corresponding to the dominant frequency and summing the results. This characterizes the phase state of the vibration signal at the current moment and will be used to determine the moment of maximum opening of the micro-slits at the edge of the manhole cover.

[0021] In a preferred embodiment, a model of the opening degree of the manhole cover edge gap, reflecting the contact state between the manhole cover and the manhole seat, is constructed using the vibration amplitude, including: Calculate the dynamic increment of the gap induced by the load : ; Building over time The varying manhole cover edge gap opening model : ; in, The vibration amplitude, These are the preset structural mapping coefficients. The preset static seal equivalent gap width, The dominant frequency of the vibration, The instantaneous phase of the vibration, This indicates taking the absolute value of the sine function.

[0022] Preferably, based on the vibration amplitude, a model of the opening degree of the manhole cover edge gap is constructed to reflect the contact state between the manhole cover and the manhole seat, so as to quantify the dynamic change of the edge gap after the manhole cover is loaded.

[0023] First, calculate the dynamic increment of the gap induced by the load. The corresponding calculation formula is: ; in, It is the vibration amplitude, which means the root mean square intensity of the manhole cover vibration signal; It is a preset structural mapping coefficient, which means the increment of the gap opening corresponding to a unit vibration amplitude. The optimal value of this parameter is obtained through a static pressure test of the manhole cover. Specifically, different static loads are applied to the target model manhole cover, the corresponding edge gap changes are measured, and then the mapping relationship between vibration amplitude and gap increment is obtained by fitting. The optimal value is 0.002mm / g. The meaning is the dynamic increment of the edge gap of the manhole cover relative to its static state after being excited by vehicle load.

[0024] It should be noted that the static pressure test specifically includes: the load gradient increases by 5% of the rated compressive load of the manhole cover (e.g., when the rated load is 200kN, the increase is 10kN each time) until the critical load at which the manhole cover produces significant elastic deformation is reached; eight measurement points are evenly distributed along the edge of the manhole cover (interval of 45 degrees), and data are recorded after stabilizing for 30 seconds at each load level. Each group of experiments is repeated 5 times and the average value is taken to eliminate random errors. Due to differences in stiffness and elastic modulus, the γ value of manhole covers of different materials and specifications must be calibrated differently. That is, the γ value of ductile iron manhole covers (high stiffness) is usually between 0.0015 and 0.0025 mm / g, while that of composite material manhole covers (low stiffness) is between 0.003 and 0.004 mm / g. The calibration data adopts linear fitting (because the vibration amplitude and the gap increment have an approximately linear relationship within the elastic deformation range).

[0025] Based on the calculated dynamic increment of the gap , build over time Model of varying manhole cover edge gap opening The corresponding calculation formula is: ; in, This is the preset static sealing equivalent gap width, which means the equivalent gap width corresponding to the edge sealing structure when the manhole cover is not subjected to vehicle load excitation. The optimal value of this parameter is obtained by testing the compression of the sealing gasket, specifically by measuring the edge gap width of the target model manhole cover under standard installation conditions, with an optimal value of 0.05mm. It is the dominant vibration frequency, which means the main frequency of the manhole cover's vibration under load; It is the instantaneous phase of vibration, which means the phase state of the manhole cover vibration signal at the current moment; It is a continuous-time variable, representing the current moment; This indicates taking the absolute value of the sine function; It should be noted that the compression test of the sealing gasket must be conducted under standard environmental conditions (temperature 23°C ± 2°C, relative humidity 50% ± 5%). Because the compression of rubber gaskets fluctuates by 3% to 5% for every 10°C temperature change, in practical applications, a temperature sensor must be used to collect the ambient temperature inside the well, and a temperature correction factor must be introduced (e.g., w0 is corrected by 1.04 times for every 10°C increase in temperature). During long-term use, the terminal's built-in edge computing module will periodically (every 6 months) compare the static RF signal strength under vibration-free conditions with the initial calibration value. If the signal strength increases by more than 8dB (corresponding to...)... If the value increases by 20%, it will start automatically. The calibration process involves back-calculating updates based on the mapping relationship between signal strength and slot width. Different types of sealing rings The measurement standards remained consistent, and a laser rangefinder (accuracy 0.001mm) was used to measure the actual gap after the gasket was compressed.

[0026] Specifically, the vibration of the manhole cover caused by vehicle load is periodic, and the change in the gap opening is related to the vibration displacement. The sine function can characterize the periodic vibration displacement. The absolute value is taken because the gap opening is a non-negative physical quantity, which can accurately reflect the pulse-like increase and recovery process of the edge gap during the vibration of the manhole cover. The meaning is any time The equivalent gap width at the edge of the well cover is used to determine the coupling conditions of electromagnetic signals inside and outside the well.

[0027] In a preferred embodiment, the effective electromagnetic transmission window ratio is calculated based on the manhole cover edge gap opening model and a preset radio frequency signal overflow threshold, including: Calculate the minimum gap width required to maintain communication. : ; Calculate the critical amplitude threshold : ; Calculate the critical ratio : ; Calculate the effective electromagnetic transmission window ratio : ; in, For carrier wavelength, The radio frequency signal overflow threshold. For link constants, The preset static seal equivalent gap width, The dynamic increment of the gap induced by load, To prevent extremely small positive numbers from being divided by zero, To find the maximum value function, This is a numerical truncation function. It is an arcsine function.

[0028] It should be noted that laboratory link testing needs to simulate the characteristics of the actual manhole environment (such as humidity inside the manhole of 60%~80%, distance between the manhole cover and the base station of 10~50m). The difference compensation adopts a graded correction mechanism: for every 10% increase in humidity inside the manhole above the laboratory standard (70%), Multiply by a correction factor of 1.08; if there are obstructions (such as silt or sand covering the terminal antenna in a well), the correction is made according to the proportion of the obstructed area to the antenna surface area (for every 20% increase in the obstructed area). Multiply by 1.12). When switching between different communication frequency bands, The NB-IoT band (1.8GHz) must be retested. Approximately -110dBm, LoRa in the low-frequency band (868MHz) has stronger penetration. The value is approximately -105dBm. The testing process must ensure that parameters such as transmit power and antenna gain remain consistent with actual applications. Installation location correction uses a distance attenuation model: for every 1m increase in the distance between the terminal installation location and the manhole cover, [the following value is applied]. Multiply by a correction factor of 1.05 (due to distance attenuation of electromagnetic signals propagating within the well) to ensure the accuracy of the link constant at different installation locations.

[0029] Preferably, based on the manhole cover edge gap opening model and a preset radio frequency signal overflow threshold, the effective electromagnetic transmission window ratio is calculated to determine the proportion of time per unit time that satisfies the electromagnetic communication conditions between the inside and outside of the well. First, the minimum gap width required to maintain communication is calculated. The corresponding calculation formula is: ; in, The carrier wavelength refers to the carrier wavelength corresponding to the communication standard used. Its value is determined by the communication frequency band; for example, when using the NB-IoT frequency band... The preferred value is 0.34m; This is the radio frequency signal overflow threshold, which means the minimum signal strength required for the receiver to demodulate the signal. The value is determined according to the demodulation threshold of the communication protocol, for example, a preferred value is -120dBm. The link constant is a parameter inherent to the link, including antenna gain and fixed path loss. Its value is obtained through laboratory link testing and is a fixed constant. Specifically, the electromagnetic coupling strength of a small gap is positively correlated with the fourth power of the gap width. Therefore, the minimum gap width required to maintain communication can be derived from this formula.

[0030] Next, the critical amplitude threshold is calculated. The corresponding calculation formula is: ; in, The preset static seal equivalent gap width has the same meaning as described above; To maximize the function, this step is designed so that the dynamic increment of the gap induced by the load exceeds the maximum value. Only then can the width of the gap at the edge of the manhole cover reach the minimum width required to maintain communication. The purpose of the function is to ensure If it is a non-negative value, Therefore, the static gap width already meets the communication requirements. Take 0.

[0031] Then the critical ratio was calculated. The corresponding calculation formula is: ; in, This refers to the dynamic increment of the gap induced by load, and its meaning is the same as described above; To prevent division by zero of extremely small positive numbers, which means avoiding numerical corrections when the denominator is zero, the preferred value is [value missing]. ; This is a numerical truncation function, which restricts the calculation result to the interval between 0 and 1; Specifically, the ratio of the critical amplitude threshold to the actual dynamic increment of the gap represents the degree of the current gap increment relative to the critical value. The truncation operation is to ensure the validity of the domain of the subsequent arcsine function calculation.

[0032] Finally, calculate the percentage of the effective electromagnetic transmission window. The corresponding calculation formula is: ; in, It is the arcsine function; Specifically, combining the manhole cover edge gap opening model ,when When, corresponding Within one oscillation period, the absolute value of the sine function is greater than or equal to The angle corresponding to the interval is This angle is related to The ratio represents the percentage of time within a period during which communication conditions are not met. Therefore, subtracting this ratio from 1 yields the percentage of the effective electromagnetic transmission window. It means the proportion of time during which the width of the gap at the edge of the manhole cover meets communication requirements within a unit vibration cycle.

[0033] In a preferred embodiment, based on the effective electromagnetic transmission window ratio and a preset communication reliability index, the number of data packet retransmissions that satisfy the transmission success probability is calculated, including: Calculate the corrected transmission probability base : ; Calculate the number of data packet retransmissions : ; in, The percentage of the effective electromagnetic transmission window. For a preset minimum positive number, This refers to the communication reliability index. It is the natural logarithm function. This is the floor function.

[0034] Preferably, based on the effective electromagnetic transmission window ratio and the preset communication reliability index, the number of data packet retransmissions that meet the transmission success probability is calculated to ensure that data transmission meets the preset reliability requirements.

[0035] First, calculate the corrected transmission probability base. The corresponding calculation formula is: ; in, The effective electromagnetic transmission window percentage refers to the proportion of time within a unit vibration cycle during which the width of the gap at the edge of the manhole cover meets communication requirements. This is a preset, extremely small positive number, meaning a correction amount to avoid undefined cases in subsequent logarithmic calculations. The preferred value is [value missing]. ; This is a function to find the maximum value. Specifically, when the effective electromagnetic transmission window accounts for... When the value is too small or even 0, use directly. This would cause subsequent natural logarithm calculations to fail. Therefore, by taking the maximum value, the transmission probability cardinality is corrected to be no less than [a certain value]. The value is used to ensure the validity of subsequent calculations.

[0036] Next, the number of data packet retransmissions is calculated. The corresponding calculation formula is: ; in, The communication reliability index refers to the probability of successful data transmission. The preferred value is determined based on the business requirements of manhole monitoring, for example, a value of 0.99. It is the natural logarithm function; This is a rounding function that converts the calculation result into an integer number, ensuring that the number of retransmissions is an executable integer.

[0037] Specifically, each data transmission is treated as an independent trial, and the probability of a successful transmission in a single attempt is approximately equal to the corrected transmission probability base. The probability of a single transmission failure is then... To ensure that the probability of at least one successful transmission is not less than Continuity must be guaranteed The probability of all attempts failing is no more than [a certain percentage]. ,Right now Taking the natural logarithm of both sides of the relation and simplifying it yields the following result. The lower limit value is then rounded up to obtain the minimum integer number of retransmissions that meet the conditions, thereby ensuring that data transmission meets the preset communication reliability index.

[0038] In a preferred embodiment, the optimal launch time offset for aligning with the maximum opening of the manhole cover edge gap is calculated based on the instantaneous phase of the vibration and the dominant vibration frequency, including: Calculate the vibration period : ; Calculate the optimal launch time offset. : ; in, The dominant frequency of the vibration, The instantaneous phase of the vibration, Pi Indicates to Modulo operation.

[0039] Preferably, based on the instantaneous phase of vibration and the dominant frequency of vibration, the optimal transmission time offset for aligning with the maximum opening of the gap at the edge of the manhole cover is calculated in time, so as to lock the data transmission time at the period when the gap opening is the largest and the electromagnetic coupling is the strongest.

[0040] First, calculate the vibration period. The corresponding calculation formula is: ; in, The term "dominant vibration frequency" refers to the dominant frequency of the manhole cover's vibration under load. The meaning is the time required for the manhole cover to complete one periodic vibration; Specifically, the dominant vibration frequency and the vibration period are a pair of inverse parameters of periodic motion. The vibration period can be directly obtained by taking the reciprocal of the dominant frequency, which provides a basis for determining the time range of the launch time.

[0041] Next, the optimal launch time offset is calculated. The corresponding calculation formula is: ; in, The instantaneous phase of the vibration refers to the phase state of the manhole cover vibration signal at the current moment. Pi is the mathematical constant and its value is a fixed constant. Indicates to The modulo operation limits the calculated time value to one oscillation cycle. Within the range; Specifically, combining the manhole cover edge gap opening model ,when hour, The absolute value of the function reaches its maximum value of 1. At this point, the opening of the gap at the edge of the manhole cover reaches its maximum value within the vibration cycle. The corresponding moment is the emission moment with the strongest electromagnetic coupling. Rearranging this equation yields... Then, the moment is converted into an offset relative to the current moment through modulo operation and limited to one vibration cycle to ensure that the launch moment is always aligned with the period of maximum gap opening.

[0042] In a preferred embodiment, a discrete transmission timing set is generated based on the optimal transmission time offset and the number of data packet retransmissions, and the radio frequency communication unit is driven to strictly perform data transmission according to the discrete transmission timing set, including: Calculate the window length for reliable coupling opportunities : ; Calculate the start time of the window : ; Calculate the first in the discrete transmit timing set Sending time : ; in, The percentage of the effective electromagnetic transmission window. The dominant frequency of the vibration, For current reference time, This is the offset amount for the optimal launch time. The number of times the data packet is retransmitted.

[0043] Preferably, a discrete transmission timing set is generated based on the optimal transmission time offset and the number of data packet retransmissions, and the radio frequency communication unit is driven to perform data transmission according to the set, so as to evenly distribute the transmission time within the effective electromagnetic transmission window and improve the probability of successful transmission.

[0044] First, calculate the window length for reliable coupling opportunities. The corresponding calculation formula is: ; in, The effective electromagnetic transmission window percentage refers to the proportion of time during which the gap at the edge of the manhole cover meets communication requirements within a unit vibration cycle. The dominant frequency of the vibration, This corresponds to the time it takes for the manhole cover to complete one periodic vibration; The meaning is the actual length of time within a single vibration cycle that satisfies the conditions for electromagnetic communication. Specifically, the duration of the time window available for communication is obtained by multiplying the effective electromagnetic transmission window ratio by the vibration period.

[0045] Next, calculate the window start time. The corresponding calculation formula is: ; in, The current reference time is the current time base corresponding to the terminal's local clock. The optimal launch time offset is defined as the offset of the moment when the manhole cover edge gap is at its maximum opening relative to the current moment. It is half the window length of a reliable coupling opportunity; Specifically, by taking the time corresponding to the optimal transmission time offset as the center position of the window and subtracting half of the window length, the starting time of the window can be obtained, so that the effective communication window can completely cover the period when the gap opening is large.

[0046] Then, the first [number] in the discrete transmission timing set is calculated. Sending time The corresponding calculation formula is: ; in, The number of retransmissions for the data packet is the minimum number of retransmissions required to meet the preset communication reliability requirements. The sequence number is the time of transmission, ranging from 1 to... ; It is the time interval between two adjacent transmission times; Specifically, the reliable coupling opportunity window length is evenly divided into... Each transmission time is set at the center of the corresponding interval, making... The subsequent transmissions are evenly distributed throughout the entire effective communication window, making full use of the communication conditions within the window and further improving the success rate of data transmission. After completing all the above calculations, the terminal drives the radio frequency communication unit to transmit according to each of the discrete transmission timing sets. Perform the data sending operation.

[0047] like Figure 2 As shown, manholes are installed beneath the road surface, with manhole covers on top. A sealing ring is installed between the manhole cover and the edge of the manhole to achieve a static seal. A monitoring terminal is fixedly installed inside the manhole. This terminal contains a battery, an accelerometer, an edge computing module, and a wireless transmission module. When vehicles load over the manhole cover, the sealing ring between the cover and the manhole deforms, creating micro-gaps. A ground base station communicating with the monitoring terminal is also located above the road surface. The sealing ring between the manhole cover and the edge of the manhole provides a static seal. When vehicles load over the manhole cover, the cover vibrates and deforms under load, causing the originally tightly fitted sealing ring to change gaps, thus creating micro-gaps between the cover and the manhole that can transmit electromagnetic signals. The monitoring terminal inside the manhole is continuously powered by a built-in battery: the accelerometer in the terminal senses the vibration transmitted from the manhole cover in real time and transmits the vibration signal to the edge computing module of the terminal; based on the vibration information, the edge computing module identifies when the micro gap is in a suitable period for electromagnetic coupling, and then triggers the wireless transmission module of the terminal to send monitoring data to the ground base station above the road surface through the micro gap between the manhole cover and the manhole, thus completing the transmission of manhole monitoring data.

[0048] It is important to note that all input data described in this solution is acquired in real-time through legal and compliant hardware interfaces with the user's full knowledge, explicit consent, and active cooperation. The preset parameters, prior constants, and statistical means are all derived from publicly available scientific literature data, de-identified general research datasets, or calibration data from laboratory environments, and do not contain any unauthorized sensitive third-party information. The system's data processing is limited to local or volatile memory computation transmitted via encrypted channels. There is no illegal collection, theft, or retention of user biometric data or infringement of user privacy without the user's knowledge. All parameter calls and generation comply with the principles of data minimization, legality, legitimacy, and necessity.

[0049] The embodiments of this example have been described above. However, this example is not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of this example, and all of them are within the protection scope of this example.

Claims

1. A method for ensuring low power consumption and data reliability in a manhole monitoring terminal based on edge computing, characterized in that: include: The vibration signal of the manhole cover is collected by the built-in accelerometer of the terminal, and the vibration main frequency, vibration amplitude and vibration instantaneous phase are extracted from it. The vibration amplitude is used to construct a manhole cover edge gap opening model that reflects the contact state between the manhole cover and the manhole seat, and the effective electromagnetic transmission window ratio is calculated based on the manhole cover edge gap opening model and a preset radio frequency signal overflow threshold. Based on the effective electromagnetic transmission window ratio and the preset communication reliability index, calculate the number of data packet retransmissions that meet the transmission success probability. Based on the instantaneous phase of the vibration and the dominant frequency of the vibration, calculate the optimal launch time offset for aligning with the maximum opening of the gap at the edge of the manhole cover in terms of time. Based on the optimal transmission time offset and the number of data packet retransmissions, a discrete transmission timing set is generated, and the radio frequency communication unit is driven to strictly follow the discrete transmission timing set to send data.

2. The method for ensuring low power consumption and data reliability of a manhole monitoring terminal based on edge computing according to claim 1, characterized in that, The vibration signal of the manhole cover is collected by the built-in accelerometer of the terminal, and the vibration main frequency, vibration amplitude, and instantaneous phase of the vibration are extracted from it, including: A discrete Fourier transform is performed on the collected discrete acceleration data sequence to generate a frequency domain energy spectrum. The maximum spectral peak in the frequency domain energy spectrum is searched, and the frequency index corresponding to the maximum spectral peak is converted into a physical frequency, which is used as the vibration dominant frequency. Calculate the root mean square value of the discrete acceleration data sequence as the vibration amplitude; Perform a Hilbert transform on the discrete acceleration data sequence to construct an analytic signal in the complex domain, calculate the complex argument of the analytic signal, and use it as the instantaneous phase of the vibration.

3. The method for ensuring low power consumption and data reliability of a manhole monitoring terminal based on edge computing according to claim 1, characterized in that, A model of the opening degree of the manhole cover edge gap, reflecting the contact state between the manhole cover and the manhole seat, is constructed using the vibration amplitude, including: Multiplying the vibration amplitude by a pre-calibrated structural mapping coefficient yields the load-induced dynamic increment of the gap. Based on the preset static sealing equivalent gap width, the product of the gap dynamic increment and the absolute value of the sine function is superimposed, wherein the frequency of the sine function is the vibration dominant frequency, and the phase shift is determined by the instantaneous phase of the vibration, thereby obtaining a time-varying manhole cover edge gap opening model.

4. The method for ensuring low power consumption and data reliability of a manhole monitoring terminal based on edge computing according to claim 3, characterized in that, The effective electromagnetic transmission window ratio is calculated based on the manhole cover edge gap opening model and a preset radio frequency signal overflow threshold, including: According to the pinhole coupling theory, the minimum gap width required to maintain communication is obtained by multiplying the fourth root of the ratio of the preset radio frequency signal overflow threshold to the link constant by the carrier wavelength. Subtract the preset static seal equivalent gap width from the minimum gap width, and take a non-negative value for the result to obtain the critical amplitude threshold. Calculate the ratio of the critical amplitude threshold to the load-induced dynamic increment of the gap, and restrict this ratio to a closed interval between zero and one, as the critical ratio; The angle corresponding to the critical ratio is calculated using the arcsine function, normalized, and then subtracted from one to obtain the effective electromagnetic transmission window ratio.

5. The method for ensuring low power consumption and data reliability of a manhole monitoring terminal based on edge computing according to claim 4, characterized in that, Based on the effective electromagnetic transmission window ratio and the preset communication reliability index, the number of data packet retransmissions that meet the transmission success probability is calculated, including: The larger of the effective electromagnetic transmission window percentage and a very small positive number is taken as the base value of the corrected transmission probability. Calculate the natural logarithm of the communication reliability index minus one, divide it by the natural logarithm of the modified transmission probability base, and round the result of the division operation up to obtain the minimum integer value required to satisfy the transmission success probability, which is used as the number of data packet retransmissions.

6. The method for ensuring low power consumption and data reliability of a manhole monitoring terminal based on edge computing according to claim 1, characterized in that, Based on the instantaneous phase of the vibration and the dominant frequency of the vibration, calculate the optimal launch time offset for aligning with the maximum opening of the gap at the edge of the manhole cover in time, including: Calculate the reciprocal of the dominant vibration frequency as the vibration period; Subtracting the instantaneous phase of the vibration from half of pi yields the phase difference value; Divide the phase difference by the product of twice pi and the dominant vibration frequency to obtain the original time deviation; The original time deviation is subjected to a modulo operation with the vibration period as the modulus, and the result is used as the optimal launch time offset.

7. The method for ensuring low power consumption and data reliability of a manhole monitoring terminal based on edge computing according to claim 1, characterized in that, Based on the optimal transmission time offset and the number of data packet retransmissions, a discrete transmission timing set is generated, and the radio frequency communication unit is driven to strictly follow the discrete transmission timing set to send data, including: Multiply the effective electromagnetic transmission window ratio by the reciprocal of the dominant vibration frequency to obtain the reliable coupling opportunity window length; Add the optimal launch time offset to the current reference time, and then subtract half the length of the reliable coupling opportunity window to obtain the window start time; Divide the reliable coupling opportunity window length by the number of data packet retransmissions to obtain the time interval for a single transmission; Based on the start time of the window, multiple time points are evenly arranged according to the time interval of a single transmission to form the discrete transmission timing set, and the radio frequency communication unit is driven to transmit data at each time point.

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