Environment information monitoring rock base composite well lid based on internet of things

Abstract

This invention discloses a rock-based composite manhole cover for environmental information monitoring based on the Internet of Things (IoT), relating to the field of smart city infrastructure technology. The manhole cover includes: a cover body and a sensing and monitoring module; the cover body is made of basalt fiber-reinforced resin-based composite material with an internal hollow sandwich structure; the sensing and monitoring module is embedded in the lower surface of the cover body and includes a sensor group, a hardware wake-up circuit, a main control unit, and a wireless communication unit; the hollow sandwich structure is filled with phase change energy storage material; the hardware wake-up circuit is connected to the sensor group and the main control unit and is continuously powered at the microampere level, used to compare the output signal of the sensor group with a preset tilt angle threshold, and only generates a trigger signal and sends it to the main control unit when the output signal exceeds the preset tilt angle threshold. This invention achieves the goals of material durability, cost control, low sensor power consumption, and data accuracy by optimizing the material structure and circuit architecture.

Description

Technical Field

[0001] This invention relates to the field of smart city infrastructure technology, and in particular to a rock-based composite manhole cover for environmental information monitoring based on the Internet of Things. Background Technology

[0002] With the advancement of smart city construction, traditional manhole covers are being upgraded towards intelligence and information technology. Environmental monitoring manhole covers based on the Internet of Things (IoT) can monitor underground water levels, harmful gas concentrations, and the condition of the manhole cover itself in real time, providing data support for urban flooding early warning, gas safety monitoring, and manhole cover anti-theft management.

[0003] Currently, smart manhole covers mainly face two major technical bottlenecks: (1) It is difficult to balance the durability and cost of the manhole cover material itself. Although metal manhole covers have high strength, they are prone to corrosion and have serious signal shielding. Traditional composite material manhole covers have high cost and are prone to creep and fatigue damage under long-term dynamic loads.

[0004] (2) There is a contradiction between the energy consumption and data accuracy of the sensing and monitoring system. In order to achieve long-term maintenance-free operation, sensors usually adopt low-power mode and intermittent sampling. However, this working mode is prone to missing sudden events, and sensor zero drift and environmental interference will lead to an increase in false alarm rate, affecting the validity of data.

[0005] Furthermore, the underground environment is extremely cold in winter and hot in summer, and drastic temperature changes can cause sensor performance drift and battery life degradation. Although current technologies attempt to reduce power consumption through timed sampling or magnetic switches, they have not yet effectively resolved the fundamental contradiction between power saving and accuracy. Summary of the Invention

[0006] The purpose of this invention is to provide a rock-based composite manhole cover for environmental information monitoring based on the Internet of Things. By optimizing the material structure and circuit architecture, it achieves the goals of material durability, cost control, low power consumption of sensors, and accurate data.

[0007] To achieve the above objectives, the present invention provides an IoT-based environmental information monitoring rock-based composite manhole cover, comprising: a manhole cover body and a sensing monitoring module; The manhole cover body is made of basalt fiber reinforced resin matrix composite material; the manhole cover body has a hollow sandwich structure inside. The sensing and monitoring module is embedded in the lower surface of the manhole cover body and includes a sensor group, a hardware wake-up circuit, a main control unit and a wireless communication unit. The hollow sandwich structure is filled with phase change energy storage material; the phase change energy storage material is used to absorb the heat generated by the manhole cover body due to environmental changes, and to maintain the stable environmental temperature inside the manhole cover body and the sensing and monitoring module. The sensor group includes a water level sensor and a gas sensor; The hardware wake-up circuit is connected to the sensor group and the main control unit and is continuously powered by microamperes. It is used to compare the output signal of the sensor group with a preset threshold and generate a trigger signal to be sent to the main control unit only when the output signal exceeds the preset threshold.

[0008] Preferably, the manhole cover body is composed of an outer layer structure and an inner layer structure; the outer layer structure uses continuous basalt fiber woven fabric as a reinforcing material, the inner layer structure uses short-cut basalt fiber as a reinforcing material, and the outer layer structure and the inner layer structure are integrally formed by a molding process.

[0009] Preferably, the thickness of the outer layer is 1 / 3 to 1 / 2 of the total thickness of the manhole cover body; the resin matrix of the inner layer contains microencapsulated self-healing agents.

[0010] Preferably, the phase change energy storage material is a paraffin-based and fatty acid-based composite phase change material with a phase change temperature of 25℃-35℃.

[0011] Preferably, the hardware wake-up circuit includes: a comparator chip and a reference voltage source; The comparator chip is connected to the sensor group and the reference voltage source; The reference voltage source is used to generate a reference voltage corresponding to a preset threshold. The hardware wake-up circuit is powered by a standby power supply independent of the main control unit.

[0012] Preferably, the sensor group further includes an attitude sensor; the output terminal of the attitude sensor is directly connected to the input terminal of the hardware wake-up circuit; the attitude sensor is continuously in a monitoring state with microampere-level power supply, and when the detected angle change exceeds a preset tilt angle threshold, the hardware wake-up circuit triggers the main control unit to wake up, and the main control unit controls the wireless communication unit to send an alarm signal.

[0013] Preferably, the main control unit has a built-in adaptive sampling algorithm for dynamically adjusting the sampling frequency of the water level sensor and the gas sensor based on the historical data of the attitude sensor and the trigger frequency of the hardware wake-up circuit.

[0014] Preferably, the wireless communication unit includes a communication module and an antenna, wherein the antenna is a flexible antenna printed on the inner surface of the manhole cover body, used to transmit signals using the wave transmission characteristics of the manhole cover body.

[0015] Preferably, the sensing and monitoring module further includes a power supply unit; the power supply unit includes a miniature vibration energy harvester, a rectifier circuit, an energy storage capacitor, and a lithium battery connected in sequence; the miniature vibration energy harvester is attached to the lower surface of the manhole cover body and is used to collect the vibration energy generated when a vehicle runs over the manhole cover and convert it into electrical energy to replenish the lithium battery.

[0016] Preferably, the gas sensor is an electrochemical sensor or a catalytic combustion sensor; the signal output terminal of the gas sensor is connected to the main control unit through a low-power analog switch; the low-power analog switch is only turned on during the sampling period.

[0017] In summary, the rock-based composite manhole cover for environmental information monitoring based on the Internet of Things provided by this invention has the following advantages compared to traditional technologies: (1) The present invention introduces an independent hardware wake-up circuit, which works continuously at the microampere level and only wakes up the main control unit when the sensor signal exceeds the threshold, so that the main control unit and the water level and gas sensors are in deep sleep when there are no events, which significantly reduces the average power consumption, extends the battery life, and greatly reduces the operation and maintenance costs.

[0018] (2) The present invention sets a hollow interlayer inside the manhole cover and fills it with phase change energy storage material. It uses the latent heat of phase change to absorb heat during the day and release it at night, so as to stabilize the working environment inside the manhole cover and the sensing module at 25℃-35℃. This solves the problem of temperature affecting the accuracy of the sensor from the root and ensures the long-term stability of water level and gas monitoring data.

[0019] (3) The present invention adopts a hierarchical architecture of hardware wake-up circuit and main control unit. The hardware wake-up circuit responds to sudden abnormal situations in milliseconds and wakes up the main control unit. After the main control unit is woken up, it is responsible for data acquisition and reporting, thus achieving the dual goals of zero missed reports and low power consumption.

[0020] (4) The manhole cover body is made of basalt fiber reinforced resin matrix composite material, which has high strength, lightweight, corrosion resistance and natural wave transmission characteristics, making it easy to install and maintain, and providing an unobstructed transmission channel for wireless communication.

[0021] (5) By monitoring the water level, gas concentration and manhole cover status in real time, the system can upgrade from manual inspection to data-driven proactive supervision, providing accurate data support for flood warning, gas pipeline safety and manhole cover anti-theft, and promoting the intelligent transformation of urban infrastructure.

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view of the overall structure of a rock-based composite manhole cover for environmental information monitoring based on the Internet of Things, as described in this invention. Figure 2 This is a schematic diagram of the material layering structure of the manhole cover body in this invention; Figure 3 This is a circuit diagram of the sensing and monitoring module in this invention; Figure 4 This is a flowchart illustrating the workflow of an IoT-based environmental information monitoring rock-based composite manhole cover according to the present invention.

[0024] Figure Labels 1. Manhole cover body; 2. Sensing and monitoring module; 3. Hollow sandwich structure; 4. Outer layer structure; 5. Inner layer structure; 6. Self-healing agent; 7. Self-healing agent shell; 8. Repair fluid. Detailed Implementation

[0025] The technical method of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0026] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0027] Techniques, systems, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the instruction manual.

[0028] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0029] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0030] This invention provides a rock-based composite manhole cover for environmental information monitoring based on the Internet of Things, such as... Figure 1 As shown, it includes: manhole cover body 1 and sensing and monitoring module 2.

[0031] The manhole cover body 1 is made of basalt fiber reinforced resin matrix composite material. The manhole cover body 1 has a hollow sandwich structure 3 inside.

[0032] The manhole cover body 1 adopts a double-layer composite structure design, such as Figure 2As shown, the manhole cover body is composed of an outer layer structure 4 and an inner layer structure 5. The outer layer structure 4 uses continuous basalt fiber woven fabric as reinforcement material and epoxy resin as matrix, and is formed by molding process to ensure that the manhole cover has sufficient compressive and impact resistance. Its thickness is 1 / 3 to 1 / 2 of the total thickness of the manhole cover body 1. The inner layer structure 5 uses short-cut basalt fiber as reinforcement material, which is mixed with epoxy resin and filled into the interior of the outer layer structure 4. It is integrally cured with the outer layer structure 4 during the molding process. Microencapsulated self-healing agent 6 is uniformly dispersed in the resin matrix of the inner layer structure 5. The outer shell 7 of the self-healing agent is urea-formaldehyde resin, and the inner shell encapsulates the repair liquid 8. The main component of the repair liquid 8 is dicyclopentadiene repair monomer. When the manhole cover is subjected to dynamic load for a long time and microcracks are generated, the crack propagation causes the microcapsules to rupture. The dicyclopentadiene repair monomer polymerizes under the action of a catalyst, fills the crack, and realizes the self-repair of the microcracks.

[0033] In an exemplary embodiment of the present invention, the outer layer structure uses continuous basalt fiber woven fabric as the reinforcing material, and the matrix is ​​bisphenol A type epoxy resin (E-51 type); the inner layer structure uses chopped basalt fibers (3-6 mm in length) as the reinforcing material, and the matrix is ​​also bisphenol A type epoxy resin (E-51 type). It is integrally molded by compression molding at a temperature of 150°C, a pressure of 15 MPa, and a holding time of 20 minutes.

[0034] Between the outer layer structure 4 and the inner layer structure 5, a ring-shaped hollow sandwich structure 3 is installed. The hollow sandwich structure 3 is a sealed cavity filled with a phase change energy storage material. The phase change energy storage material is a composite phase change material of paraffin-based and fatty acid-based materials, with a phase change temperature of 25℃-35℃. During the daytime in summer, the surface temperature of the manhole cover can reach over 50℃. When heat is conducted through the outer layer structure 4 to the hollow sandwich structure 3, the phase change energy storage material absorbs heat and undergoes a solid-liquid phase change, inhibiting further heat conduction inwards. At night, as the ambient temperature decreases, the phase change energy storage material releases the stored heat, maintaining the internal temperature of the manhole cover at approximately 25℃-35℃. This temperature control design effectively avoids measurement drift caused by drastic temperature fluctuations in the downhole sensing monitoring module.

[0035] In an exemplary embodiment of the present invention, paraffin wax slices with a melting point of 30°C and stearic acid are compounded at a mass ratio of 7:2, and a small amount of expanded graphite is added to improve the thermal conductivity, thus obtaining a paraffin-based and fatty acid-based composite phase change material. Testing showed that the phase change temperature of this paraffin-based and fatty acid-based composite phase change material is 28°C-32°C, and the phase change enthalpy is 180 J / g, which can effectively absorb the heat generated by sunlight on the manhole cover during the day.

[0036] The sensing and monitoring module 2 is encapsulated in a waterproof housing and installed on the lower surface of the manhole cover body 1. The circuit diagram of the sensing and monitoring module is shown below. Figure 3As shown, the sensing and monitoring module 2 includes a sensor group, a hardware wake-up circuit, a main control unit, a wireless communication unit, and a power supply unit.

[0037] The sensor suite includes a water level sensor, a gas sensor, and an attitude sensor. The gas sensor is either an electrochemical sensor or a catalytic combustion sensor.

[0038] The hardware wake-up circuit includes a comparator chip (using a TI TLV3691 ultra-low-power comparator with an operating current of only 0.9μA) and a reference voltage source (using a resistor divider network or a precision reference source). The output of the attitude sensor is directly connected to the positive input of the comparator chip, and the negative input of the comparator chip is connected to the reference voltage source. The preset tilt angle threshold corresponds to the output voltage of a 15° tilt angle.

[0039] The comparator chip and reference voltage source belong to different power domains than the main control unit. The hardware wake-up circuit is continuously powered directly by the lithium battery (standby power domain), while the main control unit, wireless communication unit, and sensor group are powered by the lithium battery through a power switch (controlled power domain). The attitude sensor operates continuously in the microampere level. When the manhole cover is moved, causing the tilt angle to exceed 15°, the comparator chip outputs a high-level trigger signal, waking up the main control unit from deep sleep through the interrupt wake-up pin.

[0040] The advantage of this dual power domain isolation design is that the main control unit can enter a deep sleep state with complete power failure, while the hardware wake-up circuit maintains microampere operation, which not only achieves millisecond-level event response, but also minimizes the system's standby power consumption.

[0041] The main control unit uses an ultra-low-power processor (such as the STM32L0 series processor) with a built-in adaptive sampling algorithm. Upon wake-up, the main control unit first reads detailed data from the attitude sensor to determine the event type (tilt, displacement, or vibration). Based on the severity of the attitude change and the historical trigger frequency of the hardware wake-up circuit, the algorithm dynamically adjusts the sampling strategies of the water level sensor and gas sensor. For example: If the vibration is determined to be a brief vibration caused by normal vehicle running over it (tilt angle change <5°, duration <2s) and the trigger frequency is <3 times / hour, it is determined to be a stable period, and low-frequency sampling is maintained (once per hour).

[0042] If the data is determined to be continuously tilted (tilt angle > 15° for more than 30 seconds) or triggered multiple times in a row (trigger frequency ≥ 3 times / hour), it is determined to be an active period, and high-frequency sampling (once per minute) is switched, and encrypted data is reported.

[0043] The outputs of the water level and gas sensors are connected to the analog-to-digital converter (ADC) sampling interface of the main control unit via low-power analog switches. The analog switches are only activated by the main control unit during the sampling period and immediately deactivated after sampling, cutting off the leakage path between each sensor and the ADC. According to testing, this design can reduce the static power consumption of each sensor by more than 90%.

[0044] The wireless communication unit uses a communication module that supports PSM and eDRX low-power modes. The communication module can be an LTE Cat.1 module, an NB-IoT module, or a LoRawan module. The antenna is a flexible FPC antenna, printed on the inner surface of the manhole cover body 1 near the edge. It utilizes the low-loss characteristics of basalt fiber composite material for electromagnetic waves (transmittance >95%) to achieve stable signal transmission.

[0045] The power supply unit comprises a miniature vibration energy harvester, a rectifier circuit, an energy storage capacitor, and a lithium battery, connected in sequence. The miniature vibration energy harvester uses a piezoelectric ceramic sheet (such as the PZT-5H type) attached to the center area of ​​the lower surface of the manhole cover body 1. When a vehicle rolls over the manhole cover, causing micron-level deformation, the piezoelectric sheet generates an AC voltage (peak value up to 10V-20V). This voltage is converted to DC by the rectifier circuit (a bridge rectifier composed of four Schottky diodes) and stored in the energy storage capacitor (1000μF capacity). When the voltage of the energy storage capacitor reaches a set value (e.g., 4.2V), the lithium battery is recharged via a charging management chip.

[0046] Based on actual road tests, in road sections with an average daily traffic flow of 1,000 vehicles, it can replenish approximately 30% of the energy consumed by the lithium battery, significantly extending the battery replacement cycle. The lithium battery has a capacity of 19,000mAh, and combined with the low-power design of this invention, the theoretical battery life can reach more than 10 years.

[0047] A workflow for monitoring rock-based composite manhole covers using IoT-based environmental information, such as... Figure 4 As shown, it includes the following steps: S1. The attitude sensor continuously monitors the attitude of the manhole cover and inputs the output signal into the hardware wake-up circuit for threshold judgment.

[0048] S2. Determine if the preset tilt angle threshold is exceeded: if not, return to S1; if yes, proceed to S3.

[0049] S3, the hardware wake-up circuit triggers the main control unit to wake up.

[0050] S4. After the main control unit is woken up, it determines the event type based on the attitude change characteristics, dynamically adjusts the sampling frequency of the water level sensor and the gas sensor, turns on the low-power analog switch, and collects environmental data.

[0051] S5. The main control unit performs local filtering and feature extraction on the collected environmental data to determine whether alarm conditions such as water level exceeding the limit or gas concentration exceeding the limit are triggered.

[0052] S6: If an alarm condition is triggered or the preset reporting cycle is reached (once every 6 hours by default), the main control unit wakes up the wireless communication unit and sends data (including manhole cover ID, attitude data, water level data, gas data, battery power, etc.) to the cloud server through the NB-IoT network.

[0053] S7. After the data transmission is completed, the main control unit confirms that the wireless communication unit has entered the PSM sleep state. Then, it and each sensor re-enter the sleep mode and wait for the next event to trigger.

[0054] By default, the main control unit, wireless communication unit, water level sensor, and gas sensor are all in sleep mode, with only the attitude sensor and hardware wake-up circuit in microampere-level monitoring mode. Timed wake-up is used as a redundancy backup, with a cycle set to 24 hours.

[0055] In summary, this invention systematically solves the core contradictions of power consumption, accuracy, and durability of smart manhole covers through a three-in-one design that integrates hardware wake-up, phase change temperature control, and composite materials.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An environment information monitoring rock base composite material well lid based on Internet of Things, characterized in that, The utility model relates to a kind of intelligent manhole cover, including: Manhole cover body and sensing monitoring module; The manhole cover body is made of basalt fiber reinforced resin matrix composite material;The hollow sandwich structure is arranged inside the manhole cover body; The sensing monitoring module is embedded in the lower surface of manhole cover body, including sensor group, hardware wake-up circuit, main control unit and wireless communication unit; The hollow sandwich structure is filled with phase change energy storage material;The phase change energy storage material is used to absorb the heat generated by the manhole cover body due to environmental changes, maintain the stable environment temperature inside the manhole cover body and the sensing monitoring module; The sensor group includes water level sensor and gas sensor; The hardware wake-up circuit is connected with sensor group and main control unit, and continuously in microampere level power supply working state, for comparing the output signal of sensor group with preset inclination threshold, and only when the output signal exceeds preset inclination threshold, trigger signal is generated and sent to main control unit.

2. The environment information monitoring rock base composite material well lid based on the Internet of Things according to claim 1, characterized in that, The manhole cover body is composed of outer layer structure and inner layer structure;The outer layer structure uses continuous basalt fiber woven fabric as reinforcing material, and the inner layer structure uses short-cut basalt fiber as reinforcing material, and the outer layer structure and the inner layer structure are integrally formed by molding process.

3. The environment information monitoring rock base composite material well lid based on the Internet of Things according to claim 2, characterized in that, The thickness of the outer layer structure is 1 / 3-1 / 2 of the total thickness of the manhole cover body;The resin matrix of the inner layer structure disperses microencapsulated self-repairing agent.

4. The environment information monitoring rock base composite material well lid based on the Internet of Things according to claim 1, characterized in that, The phase change energy storage material is paraffin-based and fatty acid-based composite phase change material, and the phase change temperature is 25-35℃.

5. The environment information monitoring rock base composite material well lid based on the Internet of Things according to claim 1, characterized in that, The hardware wake-up circuit includes comparator chip and reference voltage source; The comparator chip is connected with sensor group and reference voltage source; The reference voltage source is used to generate reference voltage corresponding to preset threshold; The hardware wake-up circuit is powered by a standby power source independent of the main control unit.

6. The environment information monitoring rock base composite material well lid based on the Internet of Things according to claim 5, characterized in that, The sensor group also includes attitude sensor;The output end of the attitude sensor is directly connected with the input end of the hardware wake-up circuit;The attitude sensor continuously monitors in microampere level power supply state, when the detected angle change exceeds the preset inclination threshold, the hardware wake-up circuit triggers the main control unit to wake up, and the main control unit controls the wireless communication unit to send alarm signal.

7. The IoT-based environmental information monitoring rock base composite material well lid according to claim 6, characterized in that, The main control unit is built-in adaptive sampling algorithm, which is used to dynamically adjust the sampling frequency of water level sensor and gas sensor according to the historical data of attitude sensor and the trigger frequency of hardware wake-up circuit.

8. The environment information monitoring rock base composite material well lid based on the Internet of Things according to claim 1, characterized in that, The wireless communication unit includes communication module and antenna, and the antenna is a flexible antenna printed on the inner surface of the manhole cover body, which is used for signal transmission by using the wave-transparent property of the manhole cover body.

9. The environment information monitoring rock base composite material well lid based on the Internet of Things according to claim 1, characterized in that, The sensing monitoring module also includes power supply unit;The power supply unit includes micro-vibration energy collector, rectifier circuit, energy storage capacitor and lithium battery connected in sequence;The micro-vibration energy collector is attached to the lower surface of the manhole cover body, which is used to collect vibration energy generated when vehicle rolls over the manhole cover and convert it into electric energy to supplement the lithium battery.

10. The environment information monitoring rock base composite material well lid based on the Internet of Things according to claim 1, characterized in that, The gas sensor is an electrochemical sensor or a catalytic combustion sensor;The signal output end of the gas sensor is connected with the main control unit through low-power analog switch;The low-power analog switch is only on during sampling period.

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