Urban pavement special-shaped segmented capacitive liquid level measuring device and method

Abstract

The invention provides an urban pavement special-shaped segmented capacitive liquid level measuring device and method.The device comprises a capacitor array module, a signal processing unit and a communication module, the signal processing unit comprises a capacitance detection circuit and a dielectric calculation module, and the dielectric calculation module calculates an effective dielectric constant through a designed formula; and the liquid level depth is further calculated according to the calculated effective dielectric constant. According to the urban road surface special-shaped segmented capacitive liquid level measuring device and method, the dielectric constant detection sensitivity is remarkably improved, measuring range expansion and water quality judgment are achieved in combination with an algorithm, the detection efficiency and detection precision of the urban road surface accumulated water level depth are remarkably improved, and the urban road surface special-shaped segmented capacitive liquid level measuring device and method can be widely applied to an urban flood early warning system.

Description

Technical Field

[0001] The present invention belongs to the field of municipal road surface monitoring, and in particular relates to a device and method for measuring the special-shaped segmented capacitive liquid level of an urban road surface. Background Art

[0002] Urban waterlogging is often monitored using ultrasound and laser technology. However, these monitoring devices are bulky and require support such as poles, making installation, operation, and maintenance complex and costly. Others currently use capacitance to measure liquid depth, but this measurement is affected by the dielectric constant of the liquid, making it difficult to accurately calibrate the liquid depth without measuring pollutant concentration. Consequently, these monitoring devices often suffer from significant errors. Summary of the Invention

[0003] The purpose of the present invention is to address the defects of the existing technology and provide a device and method for measuring the special-shaped segmented capacitive liquid level of urban road surfaces, which can significantly improve the detection efficiency and detection accuracy of the water level depth of urban road surface water.

[0004] A first aspect of the present invention provides a capacitive liquid level measuring device for irregularly shaped sections of urban pavement, comprising:

[0005] Capacitor array module: Consists of a base layer and an extension layer. The base layer contains multiple rows of parallel plate capacitor units connected in series. The extension layer is connected in series on top of the base layer and contains a single capacitor with an area three times that of a single row of capacitors in the base layer.

[0006] Signal processing unit: including a capacitance detection circuit and a dielectric estimation module. The capacitance detection circuit determines the highest activation row number (Max_Row) by scanning the capacitance value, and the dielectric estimation module calculates the liquid equivalent dielectric constant based on the extended layer capacitance value;

[0007] Communication module: used to transmit liquid level data;

[0008] The dielectric calculation module calculates the equivalent dielectric constant using the following formula:

[0009]

[0010] Where: ε liquid is the liquid equivalent dielectric constant; C top_wet is the capacitance of the extended layer in the liquid-covered state; C top_dry is the reference capacitance value of the extended layer capacitor in a dry state; ε air is the dielectric constant of air;

[0011] The liquid level depth H is calculated by extrapolation using the following formula:

[0012] H=Max_Row·5cm+α·(ε liquid -ε water );

[0013] Where: H is the actual water depth; Max_Row is the highest activated row number of the base layer; α is the calibration coefficient; ε water is the dielectric constant of pure water.

[0014] Preferably, the basic layer capacitor units are arranged in a serpentine zigzag pattern, and the electrodes are composed of a copper plating layer and a flexible PCB substrate; the area coverage of the extended layer capacitor electrodes is 300% of that of the basic layer.

[0015] Preferably, the capacitance detection circuit adopts an RC oscillator frequency measurement method, and the threshold trigger logic satisfies:

[0016] C i >2·C base ;

[0017] Where: C i is the capacitance measurement value of row i; C base It is the reference capacitance value in dry state.

[0018] Preferably, the calibration coefficient α is determined by experimental fitting and satisfies:

[0019]

[0020] Among them: H 实测 Calibrate water depth for laser rangefinder.

[0021] Preferably, the height difference between each row of capacitor units is 5 cm-10 cm.

[0022] A second aspect of the present invention provides a method for measuring surface water level on urban roads, using the urban road surface special-shaped segmented capacitive liquid level measuring device described in any of the above items, specifically comprising:

[0023] Connect the base layer and the expansion layer in series to form a capacitor array module, then embed the capacitor array module into the reserved groove of the asphalt pavement, connect the signal processing unit and the communication module to the power supply, and expose the communication module antenna;

[0024] After recording the reference values of each capacitor during initialization, the signal processing unit reads the capacitance data, calculates the equivalent dielectric constant, and calculates the water level depth;

[0025] When ε liquid When the calculated value of the liquid equivalent dielectric constant exceeds 80±40, an alarm will be issued and manual measurement of the water level depth will be instructed.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention provides a device and method for measuring the irregularly shaped segmented capacitive liquid level of urban pavement, which significantly improves the sensitivity of dielectric constant detection. Combined with an algorithm, it realizes range expansion and water quality discrimination, significantly improving the detection efficiency and accuracy of the depth of water level on urban road surfaces. It can be widely used in urban flood warning systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the serpentine electrode arrangement in a preferred embodiment of the present invention.

[0029] Figure 2 This is a flow chart of signal processing in the present invention.

[0030] In the above drawings: 10, capacitor array module; 11, parallel plate capacitor unit; 12, supercapacitor; 20, signal processing unit; 21, capacitance detection circuit; 22, dielectric estimation module; 30, communication module. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solution of the present invention, the preferred embodiments of the present invention are described below in conjunction with specific embodiments. However, it should be understood that the drawings are only for illustrative purposes and cannot be understood as limiting this patent; in order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted; the positional relationships described in the drawings are only for illustrative purposes and cannot be understood as limiting this patent.

[0032] As an embodiment of the present invention, see the attached Figure 1 and Figure 2 This embodiment provides a capacitive liquid level measuring device for irregularly shaped sections of urban roads, comprising:

[0033] Capacitor array module 10: consists of a base layer and an extension layer. The base layer includes multiple rows of parallel plate capacitor units 11, which are connected in series. The extension layer is connected in series on top of the base layer and includes a super capacitor 12 with a single capacitor area three times that of a single row of the base layer capacitor.

[0034] Signal processing unit 20: includes a capacitance detection circuit 21 and a dielectric estimation module 22. The capacitance detection circuit 21 determines the highest active row number (Max_Row) by scanning the capacitance value, and the dielectric estimation module 22 calculates the liquid equivalent dielectric constant based on the extended layer capacitance value;

[0035] Communication module 30: used to transmit liquid level data; wherein,

[0036] The dielectric calculation module calculates the equivalent dielectric constant using the following formula:

[0037]

[0038] Where: ε liquid is the liquid equivalent dielectric constant; C top_wet is the capacitance of the extended layer in the liquid-covered state; C top_dry is the reference capacitance value of the extended layer capacitor in a dry state; ε air is the dielectric constant of air;

[0039] The liquid level depth (H) is calculated by extrapolation using the following formula:

[0040] H=Max_Row·5cm+α·(ε liquid -ε water );

[0041] Where: H is the actual water depth; Max_Row is the highest activated row number of the base layer; α is the calibration coefficient; ε water is the dielectric constant of pure water.

[0042] In some preferred embodiments, Figure 1 As shown, three groups of parallel capacitor array modules 10 can be set in the horizontal direction. In this way, the direction of incoming water can be inferred through the capacitance data detected by the three groups of capacitor array modules 10. That is, when it is detected that the water level on the right is higher than the water level on the left, it means that the water flows from the left to the right, thereby providing basic information for the next step of emergency response.

[0043] In some preferred embodiments, the base layer capacitor units are arranged in a serpentine zigzag pattern, and the electrodes are composed of a copper plating layer and a flexible PCB substrate; the extended layer capacitor electrode area coverage is 300% of the base layer. In the above embodiment, the height difference of each row of capacitor units is 5cm-10cm, preferably 5cm. The use of serpentine electrodes extends the electric field path, and the capacitance change ΔC increases by 3 times. The traditional linear electrode ΔC = 5pF, while the serpentine electrode used in the present invention has a ΔC = 15pF, thereby being able to detect a small water level change of 2mm, greatly improving the accuracy of water level measurement.

[0044] As we all know, the capacitance C of a capacitor is proportional to the electrode area A and the dielectric constant ε, and inversely proportional to the plate spacing d. The formula is:

[0045]

[0046] Where ε0 is the dielectric constant of vacuum; ε r is the relative dielectric constant of the medium between the plates.

[0047] When the extended layer capacitor area A is set to 3 times that of the base layer, the absolute change in capacitance increases significantly when the dielectric constant changes. When the liquid covers the extended layer, the capacitance change ΔC is proportional to the electrode area. If the area of a single row of base layer capacitors is A and the area of the extended layer is 3A, then:

[0048] ΔC 扩展层 =3·ΔC 基础层 ;

[0049] At this time, at the same water level, the capacitance change of the extended layer is three times that of the base layer; the signal-to-noise ratio (SNR) is improved by about 6dB, and the dielectric constant calculation error is <1%, while the dielectric constant calculation error in the traditional solution is >5%.

[0050] Furthermore, using large electrodes in the extended layer reduces distortion at the electric field edges, making measurements more stable. Even when oil or sediment partially covers the electrodes, the remaining effective area still ensures detection. In practice, it was found that when the oil film covered 50% of the electrode area, the extended layer capacitance deviation was less than 5%, while the traditional solution showed a deviation of more than 30%.

[0051] In some preferred embodiments, the capacitance detection circuit adopts an RC oscillator frequency measurement method, and the threshold trigger logic satisfies:

[0052] C i >2·C base ;

[0053] Where: C i is the capacitance measurement value of row i; C base It is the reference capacitance value in dry state.

[0054] In the above embodiment, the dynamic threshold is adaptively adjusted based on the dryness reference value Cbase, which can avoid false triggering caused by temperature and humidity drift and reduce the false alarm rate of the fixed threshold. At the same time, under heavy rain weather conditions, the data update frequency is faster, which can achieve the purpose of real-time measurement.

[0055] In some preferred embodiments, the calibration coefficient α is determined by experimental fitting and satisfies:

[0056]

[0057] Among them: H 实测 Calibrate water depth for laser rangefinder.

[0058] In the above embodiment, α is dynamically adjusted based on the measured water depth and the equivalent dielectric constant of different liquid types, which can adapt to complex liquids such as oil, mud, and sand, reducing measurement errors. During use, it is automatically calibrated once a month, and no manual maintenance is required for two years.

[0059] As another preferred embodiment of the present invention, this embodiment provides a method for measuring water level on urban roads, using the method for measuring water level on urban roads described in any of the above embodiments, specifically comprising:

[0060] Connect the base layer and the expansion layer in series to form a capacitor array module, then embed the capacitor array module into the reserved groove of the asphalt pavement, connect the signal processing unit and the communication module to the power supply, and expose the communication module antenna;

[0061] After recording the reference values of each capacitor during initialization, the signal processing unit reads the capacitance data, calculates the equivalent dielectric constant, and calculates the water level depth;

[0062] When ε liquid When the calculated value of the liquid equivalent dielectric constant exceeds 80±40, an alarm will be issued and manual measurement of the water level depth will be instructed.

[0063] In the above embodiment, the dielectric constant ε is used to distinguish between clean water (ε≈80), oily dirt (ε

[0064] ≈2.5), sandy sewage (ε≈5-15); water quality classification accuracy is 92%. When water quality is abnormal, it can promptly monitor and obtain water quality signals, and then prompt manual water level measurement to enable more targeted manual re-measurement. This can improve the efficiency of water level monitoring in key areas of urban roads and enhance the effectiveness of urban flood disaster warning.

[0065] Provided below are different calculation scenarios for monitoring waterlogging on urban roads in a certain city.

[0066] In this embodiment, the base layer of the capacitor array module features 10 rows of capacitors arranged in a zigzag pattern, with a 5cm height difference between rows, for a total height of 50cm. The electrodes are 2mm wide, 1mm apart, and the copper plating is 0.1mm thick. The surface is coated with a nano-hydrophobic coating with a contact angle >150°. The extended layer features a single row of capacitors measuring 30cm x 10cm, with the electrode spacing increased to 5mm to enhance dielectric sensitivity. The signal processing unit and solar power supply system (5V / 2W) are integrated into the roadside control box.

[0067] Dry state reference calibration: record the reference value of each capacitor (C base =15pF±0.5pF), extended layer C top_dry =50pF.

[0068] The water accumulation detection process is as follows:

[0069] 1. Light rain stage (water depth 12cm):

[0070] Capacitors in rows 1-3 are activated (C1-C3 = 45pF > 2×C base =30pF), Max_Row=3;

[0071] Extended layer capacitance C top_wet =135pF, calculate:

[0072]

[0073] Water depth calculation:

[0074] H=3×5+0.2×(2.7-80)=15.34cm;

[0075] The laser rangefinder measured 15.5cm, with an error of 0.16cm.

[0076] 2. Heavy rain stage (water depth 68cm):

[0077] The base layer is fully activated (Max_Row=10), and the extended layer capacitance C_top_wet=400pF;

[0078] Calculate ε=8 (contains sediment and sewage), water depth calculation:

[0079] H=10×5+0.2×(8-80)=50-14.4=35.6cm;

[0080] In this case, when the deviation between ε and pure water is greater than 50%, the "abnormal water quality" alarm is triggered, prompting a switch to ultrasonic-assisted measurement. The actual measured value using ultrasonic-assisted measurement is 68 cm.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A capacitive liquid level measuring device for special-shaped sections of urban roads, characterized in that: include: Capacitor array module: composed of a base layer and an extension layer, wherein the base layer includes multiple rows of parallel plate capacitor units, and the multiple rows of parallel plate capacitor units are connected in series; The extension layer is connected in series on top of the base layer and includes a single ultra-large capacitor with an area three times that of a single row capacitor of the base layer; Signal processing unit: including a capacitance detection circuit and a dielectric estimation module. The capacitance detection circuit determines the highest activation row number (Max_Row) by scanning the capacitance value. The dielectric estimation module calculates the liquid equivalent dielectric constant based on the extended layer capacitance value. Communication module: used to transmit liquid level data; The dielectric calculation module calculates the equivalent dielectric constant using the following formula: Where: ε liquid is the liquid equivalent dielectric constant; C top_wet is the capacitance of the extended layer in the liquid-covered state; C top_dry is the reference capacitance value of the extended layer capacitor in a dry state; ε air is the dielectric constant of air; The liquid level depth H is calculated by extrapolation using the following formula: H=Max_Row·5cm+α·(ε liquid -e water ); Where: H is the actual water depth; Max_Row is the highest activated row number of the base layer; α is the calibration coefficient; ε water is the dielectric constant of pure water.

2. The capacitive liquid level measuring device for special-shaped sections of urban roads according to claim 1, characterized in that: The basic layer capacitor unit is arranged in a serpentine fold line, and the electrodes are composed of a copper plating layer and a flexible PCB substrate; the area coverage of the extended layer capacitor electrode is 300% of the basic layer.

3. The capacitive liquid level measuring device for special-shaped sections of urban roads according to claim 1, characterized in that: The capacitance detection circuit adopts the RC oscillator frequency measurement method, and the threshold trigger logic satisfies: C i >2·C base ; Where: C i is the capacitance measurement value of row i; C base It is the reference capacitance value in dry state.

4. The capacitive liquid level measuring device for irregularly shaped urban road surfaces according to claim 1, characterized in that: The calibration coefficient α is determined by experimental fitting and satisfies: Among them: H 实测 Calibrate water depth for laser rangefinder.

5. The capacitive liquid level measuring device for irregularly shaped urban road surfaces according to claim 1, characterized in that: The height difference of each row of capacitor units is 5cm-10cm.

6. A method for measuring water level on urban roads, characterized in that: The method for measuring water level on urban roads according to any one of claims 1 to 5 specifically comprises: Connect the base layer and the expansion layer in series to form a capacitor array module, then embed the capacitor array module into the reserved groove of the asphalt pavement, connect the signal processing unit and the communication module to the power supply, and expose the communication module antenna; After recording the reference values of each capacitor during initialization, the signal processing unit reads the capacitance data, calculates the equivalent dielectric constant, and calculates the water level depth; When ε liquid When the calculated value of the liquid equivalent dielectric constant exceeds 80±40, an alarm will be issued and manual measurement of the water level depth will be instructed.

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