WO2021088490A1

WO2021088490A1 - Method for synchronously transmitting pressure collection data in multi-node distribution of building

Info

Publication number: WO2021088490A1
Application number: PCT/CN2020/113000
Authority: WO
Inventors: 汪祖民; 刘乐钰; 郑祖朋; 秦静; 季长清
Original assignee: 大连大学
Priority date: 2019-11-04
Filing date: 2020-09-02
Publication date: 2021-05-14
Also published as: CN110809044A

Abstract

A method for synchronously transmitting pressure collection data in the multi-node distribution of a building, wherein the method belongs to the technical field of information. In order to solve the problem of more accurate pressure collection and transmission for a building, the method comprises the following steps: S1, arranging nodes in a building, and constructing a network route; and S2, acquiring the state and energy usage information of each node, realizing time synchronization of two adjacent nodes, and transmitting data by means of role transformation. The effect is the improvement of the reliability and effectiveness of data transmission after pressure collection.

Description

Synchronous transmission method of pressure acquisition data distributed by multiple nodes in building

Technical field

The invention belongs to the field of information technology and relates to a real-time monitoring system for the force balance of a building based on a passive sensor network.

Background technique

In terms of building safety inspection, the X-ray method, eddy current method, optical diagnosis method, etc., commonly used in China at first, use the inspection of local buildings to determine the safety status of the overall building, but this method of inspection has great disadvantages. . With the development of information technology, some people later used optical fiber communication technology to detect remote buildings. However, the use area and performance of this method are limited. After that, people began to use wireless sensors to install and lay out the bridge structure to detect its health. However, sensors are arranged in the entire bridge structure. If the bridge structure is relatively small, but the bridge structure is large, the number of sensors that need to be installed is large. Many researchers now apply wireless sensors to buildings to periodically detect the information of the buildings. Compared with some previous methods, it improves the accuracy and overall performance of the data. However, traditional wireless sensors are powered by batteries. Once the sensor battery has no power, the sensor network cannot work. In addition, a lot of manpower and material resources need to be consumed in the later battery replacement process, a large number of battery replacements will also cause environmental waste, and long-term replacement will also cause a lot of waste of funds.

Summary of the invention

In order to solve the problem of more accurate pressure collection and transmission for buildings, the present invention proposes the following technical solution: a method for synchronous transmission of pressure collection data distributed across multiple nodes in a building, including the following steps:

S1. Deploy nodes in the building and construct network routing;

S2. Obtain the status and energy usage information of each node, realize time synchronization for two adjacent nodes, and transmit data through role conversion.

Further, the method of arranging nodes is: arranging the nodes in the same building surface of the building or arranging the nodes in multiple areas in the supporting surface of the bridge. When the same area is arranged, the nodes are equalized, and the adjacent nodes are equalized. Keep the same distance between them; the support surface of the bridge includes the support surface of the bridge support and the bridge span pavement. The support surface of the bridge support distributes more nodes. For an area where nodes are laid, there is an area where nodes are laid out symmetrically. , And the node layout surface is symmetrical as a whole, so that data comparison can be made on whether the symmetrical area is pressure balanced.

Further, the method for building a tree-shaped network route for a bridge is: a route composed of nodes of a bridge support, and the name of each node on it is composed of the number of the support-the code of the support-the number of the node; the bridge has more A bridge support, a route composed of pavement nodes between every two adjacent supports, the name of each node on it is composed of the number of the pavement-the code of the pavement-the number of the node; all the supports and all the pavements are composed The large network is shown in the figure, and the total routing is formed.

Further, the data transmitted through the network of each bridge support and the road surface analyzes the force of the entire bridge. According to the established network route, the node transmits the data to the management platform through the route.

Further, a node in a certain network transmits the data to the network route, and then transmits it through a parent route on the route network, and transmits it all the way up, and finally transmits it to the management platform through the sink node and the Internet for receiving and receiving data. Force method analysis.

Further, obtain the status of each node, including sleep/wake state and energy use state. After forming the network, the node needs to know the information of neighboring nodes and obtain it by sending information signals. The operation of the node is in the awake state. In the network, the nodes in the network have their own data transmission slot numbers, and each operation cycle will be allocated according to the number of hops of the route for node data transmission.

Further, the method of node data transmission is: first the node collects the force information, and then saves it in the local cache, senses the synchronization period of the neighbor nodes, and through time synchronization, judges the remaining energy of the current node according to the data size of the node and the distance between the neighbor nodes. Whether it can meet the energy demand for processing data, and use the role conversion method to transmit node data according to whether the buffer data reaches the threshold.

Further, it also includes step S3. Early warning after the analysis of the bridge force, an early warning indicator system is installed at the entrances of both ends of the bridge and on both sides of each section of the road, which is mainly composed of early warning indicators, capacitors, and radio frequency signal collection. It is composed of modules. The radio frequency signal acquisition module collects radio frequency signals and converts it into electrical energy. It is connected to the capacitor through the power line to store the electrical energy in the capacitor. When it is detected that the capacity of the capacitor is lower than a certain amount of storage, the node performs energy collection, and If it is detected that the electric capacity of the capacitor is full, the node enters the dormant state and no longer collects radio frequency signals. The warning indicator system receives the analysis results given by the management platform and the warning information of the road network. If the part of the road is overloaded, then Carry out a light alarm.

Further, the warning includes:

Support early warning: force collection at both ends of the same support, by comparing the collected force and the pressure that the support can withstand, to judge whether the force bearing is overloaded, if the force is too heavy, it will be overloaded The warning is uploaded to the management terminal, and the warning indicators at both ends of the support are lit up in yellow. If the load continues to be overloaded, the warning indicator will turn red, and the data will be uploaded to the management terminal for processing. If the other supports are balanced, they will light up. Green light

Road warning: Detect data on the same section of the road. If there is an overload on a certain side of the road or in a certain area, the warning indicators at both ends of the road will turn on yellow. If the overload continues, the red lights will turn on and the data will be uploaded. To the management end processing;

Early warning at both ends of the bridge: If a certain section of the support or road network has continuous stress overload, the warning lights on both sides of the bridge head will be red. The driver can know that the bridge is overloaded according to the warning lights, and then prohibit driving into the bridge to avoid the occurrence of stress overload. The risk of bridge damage caused by force overload.

Furthermore, it also includes bridge usage prediction: save the data uploaded by each support network and pavement network, analyze the data through big data technology, and get a diagram of changes in the bridge force, predict the service life of the bridge, and make it ahead of time. Prevent dangerous accidents caused by bridges that have been used for too long.

Beneficial effects: The present invention improves the reliability and effectiveness of data transmission after pressure collection.

Description of the drawings

Figure 1 is a schematic structural diagram of a building force balance monitoring system based on a passive sensor network;

Figure 2 is a schematic diagram of superframe adjustment, where (a) is the frame adjustment when the charging rate of the child node is greater than that of the parent node, and (b) is the frame adjustment when the charging rate of the child node is less than the parent node;

Figure 3 is a schematic diagram of superframe extension;

Figure 4 is a schematic diagram of superframe reduction;

Figure 5 is a schematic diagram of the role switching mechanism, in which (a) is a data transmission diagram, (b) is a role switching diagram performed by a node in a continuous work cycle;

Figure 6 is a node layout diagram, in which (a) is a partial structure diagram of the bridge, (b) is a support network layout diagram; (c) is a pavement network layout diagram;

Figure 7 is a tree-shaped network topology routing diagram, in which (a) is a support network routing diagram, (b) a road network routing diagram, (c) a bridge total network routing diagram, (d) a total network routing diagram;

Figure 8 is a schematic diagram of the early warning indicator light structure;

Figure 9 is a flow chart of node information transmission.

1. Pressure sensing module, 2. Data transmission rod, 3. Pressure sensor module, 4. Radio frequency signal acquisition module, 5. Warning indicator, 6. Road node network, 7. Bridge deck, 8. Support node network, 9. .Support rod, 10. Capacitor, 11. Power cord, 12. Smart pebble.

Detailed ways

Embodiment 1: A passive sensor network building force balance monitoring system, including several nodes arranged in the same building surface of the building or in the supporting surface of the bridge, the nodes are mainly composed of pressure sensor modules and radio frequency signal collection It consists of a module and a network module. The sensing surface of the pressure sensor module collects building pressure information and transmits it to the pressure sensor module. The pressure sensor module receives the electric energy provided by the radio frequency signal acquisition module, converts the pressure information into data, and uploads it to the network through the network module If the capacity of the radio frequency signal acquisition module is less than the set threshold, the pressure sensor module enters the sleep state. At this time, the radio frequency signal acquisition module collects radio frequency signals and converts them into electrical energy. When the electrical energy storage reaches a high set threshold, the pressure sensor The module changes from the sleep state to the active state for data collection or transmission.

Further, the node has a pebble-shaped shell, each module is located in the shell, and the sensing surface of the pressure sensing module is part or all of the top surface of the pebble shell.

Further, the pressure sensor module and the pressure sensor module are connected through a data transmission rod and perform signal transmission.

Further, the building force balance monitoring system of the passive sensor network implements a time synchronization method for data transmission between nodes, so that two adjacent nodes wake up synchronously, and data can be transmitted between two adjacent nodes .

Further, the data transmission between two adjacent nodes uses a role conversion method.

As a preferred solution, it can also be used as an independent solution to realize the method of data transmission between two adjacent nodes, the node data transmission method, through the time synchronization method, the two adjacent nodes are waked up synchronously, the two Adjacent nodes are synchronized in time. After waking up, the node judges its data cache, if:

Scenario 1: The data cache of the node is less than the threshold, and the node acts as a parent node to collect data without transmitting data, and calculate whether its remaining energy can collect data and make the data cache greater than the threshold;

If the remaining energy cannot be maintained until the data cache is greater than the threshold, calculate the next synchronization wake-up time of the node and its neighboring child nodes, and enter the sleep state when its energy is exhausted, and wait for the next time synchronization wake-up;

If the remaining energy is sufficient to maintain the data cache greater than the threshold, calculate the next synchronization wake-up time of the node and its neighboring parent node, and at the time of this wake-up, if the data cache is greater than the threshold, the node is converted to a child node Role, transfer and collect data, without collecting data, when its energy is exhausted and enter the sleep state, waiting for the next time to wake up synchronously;

Scenario 2: The data cache of the node is greater than the threshold, and the node acts as a child node to transmit data without collecting data, and calculate whether its remaining energy can transmit the data in the data cache to the data cache is less than the threshold;

If the remaining energy cannot be maintained until the data cache is less than the threshold, calculate the next synchronization wake-up time of the node and its neighboring parent node, and enter the sleep state when its energy is exhausted, and wait for the next time synchronization wake-up;

If the remaining energy is sufficient to maintain the data cache greater than the threshold, calculate the next synchronization wake-up time of the node and its neighboring child nodes, and at the time of this wake-up, if the data cache is less than the threshold, the node is converted to a parent node The character collects data without transmitting data. When its energy is exhausted, it enters the sleep state and waits for the next time to wake up synchronously.

As a preferred solution, it can also be used as an independent solution to achieve time synchronization wake-up between two nodes, that is, time synchronization method: there are two situations between adjacent parent and child nodes: one is that the superframe of the child node is greater than The superframe size of the parent node. The other is that the superframe size of the parent node is larger than the superframe size of the child node. The adjustment method is: change the size of the superframe in one node and keep the size of the superframe unchanged in the other node. , In order to realize the time synchronization of the two nodes.

Further, the synchronization method for the first case is: when the charging rate of the child node is faster than the charging rate of the parent node, the size of the child superframe will be smaller than the size of the parent superframe. The beacon message of the node's superframe time information is used to determine the start time of the next frame of the parent node. When receiving beacon information, the child node uses the beacon information to adjust its superframe to make its frame start time Align with the start time of the parent node, add a duty cycle to the end of the sub-superframe to extend it. Within this extended duty cycle, the child node wakes up and starts to consume a predetermined energy, then goes back to sleep and starts again Charge so that the energy at the beginning of the duty cycle is equal to the energy at the end of the duty cycle, the size of the superframe between the parent and child nodes is equal, and the node time is synchronized.

Further, the method of calculating the time for the child node to wake up and start to consume the predetermined energy is: n*t time has been transmitted in the frame before the child node receives the beacon message, Tc is the time spent on energy, Tc is calculated as follows: T1 is the remaining time in the current frame, T2 is the sleep time in the duty cycle, T3 is the time occupied by the secondary duty cycle, T3 is the sum of the time Tc and Th, and Tc is the consumption of some energy The time spent, Th is the time required to collect these energy, the time it takes for the parent node to start the next frame, Tparent is the sum of T1, T2, and T3, that is

T1+T2+T3=Tparent

Then: T1+T2+Tc+Th=Tparent formula (1)

The energy consumed during the secondary duty cycle or adjustment time must be equal to the energy harvested during the same duty cycle, namely:

Ec=Eh, Tc*Rc=Th*Rh

Putting formula (1) into Th, we get:

The total time the child node spends in the current superframe is equal to the sum of the time the child node has spent, the time remaining in the current awake state, and the time required for the child node to fully charge:

T1+T2+(n*t)=Tchild formula (4)

Incorporating formula (3) into formula (4), we get:

Sorted out:

Further, the synchronization method for the second case is: when the charging rate of the child node is slower than the charging rate of the parent node, the size of the child superframe will be larger than the size of the parent superframe. When receiving the beacon information, the child The node has passed the n*t time of the frame and left part of the energy. Calculate how long the child node should continue in the current frame to align itself to the parent node. The child node shrinks its duty cycle to make the child node and The parent node is aligned.

Further, the method of calculating how long the child node should continue in the current frame to align itself to the parent node is: T1 is the time for the child node to continue the current frame and consume energy, T2 is the time required for the child node to fully charge, T1 The calculation method is as follows:

T1+T2=Tparent formula (6)

When receiving a beacon message from the parent node, the remaining energy in the child node is calculated from the energy it has consumed in the current frame, expressed by the following formula:

Eleft=Efull-(n*t)*Rc formula (7)

The sum of the energy consumed and harvested and the remaining energy of the child node must be equal to the total charge, namely:

Efull=Eleft-(T1*Rc1)+(T2*Rh1) formula (8)

Incorporating formula (7) into:

Efull={Efull-(n*t)*Rc}-(T1*Rc1)+(T2*Rh1)

T1*Rc1=(T2*Rh1)-((n*t)*Rc)

Incorporating formula (6), we get:

T1*Rc1={(Tparent-T1)*Rh1}-((n*t)*Rc)

T1*{Rc1+Rh1}=(Tparent*Rh1)-((n*t)*Rc)

Among them: n is the operating cycle, t is the time of each cycle, Ec is the energy consumed, Eh is the energy harvested, Rh is the energy collection rate, Rc is the energy consumption rate, Eleft is the remaining energy, and Efull is the total energy , Tchild is the total time spent by the child node in the current superframe, Rc1 is the energy consumption rate of the child node continuing the current frame, and Rh1 is the energy collection rate of the child node continuing the current frame.

As a preferred solution, it can also be used as an independent solution, which can realize the role conversion of the node. When the role is switched and return to the original role, the data can be resumed:

The node that sends the data is the child node, and the node that receives the data sends the data from the first node to the third node. The first node must forward the data to the second node, and the second node stores the data in the buffer. Then the second node transfers the data to the third node as a continuous message flow. The data can only be transferred to one node at a time. The second node has two different roles in data transfer, the parent node and the child node;

First, the second node is in the role of the parent node, and it receives the data packet sent by the first node as the child node;

Then, the second node switches its role to a child node, and forwards the data packet to the third node as the parent node;

In the above process, the second node makes a role change in the process, the second node plays one of the two roles at different times according to specific conditions, and determines the role that the second node currently needs to play according to the buffer size of the second node;

When the buffer space in the second node is free and can accept data from other nodes, the second node acts as the parent node and receives the data transmitted by its child nodes; when the buffer of the second node is full and cannot accept the change In the case of multiple data packets, the second node acts as a child node, and the second node as a child node sends data to the parent node to release buffer space.

Further, when the buffer of the second node reaches 80% of the full capacity, the second node switches from the role of the parent node to the role of the child node; when the buffer of the second node reaches 10% of the full capacity, the second node changes from the child The role switches to the parent role.

Further, when a node acts as a parent node, it fixes a reference point in the time dimension. After the node is converted from a parent node to a child node, the original child node of the node may still be waiting to communicate with it. The node needs to record its own frame displacement. Re-adjust itself back to its reference point to switch back to the role of the original parent node and communicate with the original child node again; the method to calculate the frame displacement is:

Shift=Minimum Duty Cycle Time-Total Frame Shifts

Shift is the movement displacement when the child node is converted to the parent node, Minimum Duty Cycle Time is the minimum duty cycle, Total Frame Shifts is the total adjustment time;

As a preferred solution, it can also be used as an independent solution. The method for synchronous transmission of pressure collection data distributed across multiple nodes in a building includes the following steps:

S1. Deploy nodes in the building and construct network routing;

Further, the method of node data transmission is: first the node collects the force information, and then saves it in the local cache, senses the synchronization period of the neighbor nodes, and through time synchronization, judges the remaining energy of the current node according to the data size of the node and the distance between the neighbor nodes. Whether it can meet its energy requirements for processing data, and use the role switching method for node data transmission according to whether the buffer data reaches the threshold. The specific transmission method of the node data transmission method is the node data transmission method in the above embodiment.

Further, it also includes step S3. Early warning and alarm after the analysis of the bridge force, the early warning indicator system is set at the entrances of both ends of the bridge and on both sides of each section of the road, which is mainly composed of early warning indicators and radio frequency signal collection The module collects radio frequency signals, converts it into electrical energy, and connects to the capacitor through the power line to store the electrical energy in the capacitor. When it is detected that the capacity of the capacitor is lower than a certain amount of storage, the node performs energy collection, and if the capacity of the capacitor is detected When the reserve is full, the node enters a dormant state and no longer collects radio frequency signals. The purpose is to store and supply radio frequency power because the warning indicator needs a stable and longer power supply, which can improve the stability of power supply. For the pressure sensor to collect data and transmit data is instantaneous, real-time supply can meet its needs. At the same time, the early warning indicator system receives the analysis results given by the management platform and the warning information of the road network. If the part of the road is overloaded, a light alarm is issued. The early warning indicator is supported by the support rod, and the early warning indicator system and the capacitor pass through the power supply. Wire connection, the support rod is connected to the shell in which the capacitor is installed, and the shell supports the bottom.

Further, the warning includes:

Support early warning: First, the two end nodes of the same support (smart pebbles can be selected) carry out force collection. By comparing the collected force and the pressure that the support can withstand, it is judged whether the force bearing is overloaded, if it occurs If the force is too heavy, the overload warning will be uploaded to the management terminal. At the same time, the warning indicators at both ends of the support will turn on yellow. If the force is continuously overloaded, the warning indicator will turn red, and the data will be uploaded to the management terminal for processing. If the seat is balanced (within the normal range), the green light will be on.

Road warning: Detect data on the same section of the road. If there is an overload on a certain side of the road or in a certain area, the warning indicators at both ends of the road will turn on yellow. If the overload continues, the red lights will turn on and the data will be uploaded. To the management end processing.

Early warning at both ends of the bridge: If a certain section of the support or road network has continuous stress overload, the warning lights on both sides of the bridge head will be red. The driver can know that the bridge is overloaded according to the warning lights, and then prohibit driving into the bridge to avoid it. The risk of damage to the bridge caused by overload.

Furthermore, the collected data can be used to predict the use of bridges. The data uploaded by each support network and road network are saved, and the data is analyzed through big data technology to obtain a diagram of changes in the bridge force, which can predict the bridge’s performance. Service life, so that dangerous accidents that may occur due to the long service life of the bridge can be prevented in advance.

The intelligent pebble network real-time monitoring of the force balance method of the building adopted by the present invention can monitor the force status of the building and its safety status in real time. According to the collected force information, it is judged whether the current building is in a normal and safe state. If the force is unbalanced, that is, the side force is too large, so that it exceeds its bearing range, an alarm will be issued and the treatment will be made in time, such as Figure 9. Through the use of smart pebbles, the waste of energy and resources is reduced, and the life cycle of the sensor is increased. The method is used in house construction and bridge construction, which will greatly increase the safety of the building.

In the present invention, the passive pressure sensor is made into "intelligent pebble", embedded in the building, and real-time monitoring of the force of each building support interface in the building construction and bridge construction. The system can show the force of a certain area in the building When the force range is severely exceeded, an alarm will be issued immediately, and a warning indicator will flash and a warning will be given. While real-time monitoring of the force on the main support interface of the building is realized, the waste of battery energy of the sensor is reduced, and the quality and safety of the building are effectively improved. And the monitoring area can be monitored all-weather without blind spots. Overcome the limitations of existing sensors used in buildings.

The invention uses passive sensors and passive sensor network data transmission, obtains radio frequency signals in the environment and converts them into electrical energy to provide energy for the sensors, thereby reducing the waste of funds. The use of this method can make the sensor work all the time, increasing the life cycle of the sensor network. The smart pebbles can be embedded in buildings because of their shape, which can more realistically detect the force of buildings and monitor the safety status of buildings in real time.

The pressure sensor is also called the load cell. Highly sensitive to pressure, the intelligent pebble network composed of a large number of passive pressure sensors can collect the overall force information of buildings or bridges, detect construction safety or house quality in buildings, or predict the service life of buildings, etc. provide data. The smart pebble collects data in the active state and collects energy in the sleep state, and the smart pebble network can work continuously. Its huge data collection and detection potential make it have great application prospects in detecting the overall force information of the bridge structure or the safety information of the building, and the use of passive sensor modules reduces the number of batteries compared to traditional battery sensors. Replacement, consumption, reduce maintenance costs. The hardware technology principle on which the present invention is based is mainly the communication technology of the sensor network. The innovations in the application of the present invention are mainly embodied in: the smart pebble is embedded in the force interface of the building to collect force data; the data transmission technology in the smart pebble network.

However, the data transmission between sensor nodes is difficult to achieve time synchronization, because the data collection rate, energy collection rate, and energy collection time between each node are different. Therefore, problems such as loss in data transmission and collisions between nodes are prone to occur. In the present invention, in view of this problem in the network, a time synchronization mechanism and role conversion technology are proposed to realize data transmission between sensor nodes and improve the accuracy of data transmission.

Embodiment 2: As shown in Fig. 1 is a structure diagram of a smart pebble, which is composed of a pressure sensor module, a data transmission rod, a radio frequency signal acquisition module, and a pressure sensor module. The pressure sensor module senses pressure information and transmits it to the pressure sensor module through the data transmission rod. The pressure sensor module uses the electric energy provided by the radio frequency signal acquisition module to convert and analyze the pressure information into data, and upload it to the routing network for processing through the built-in antenna. When the electric capacity is less than a certain threshold, the radio frequency signal acquisition module enters the sleep state to collect radio frequency signals and convert them into electric energy. When the electric energy storage reaches a high threshold, it changes from the sleep state to the active state for data collection.

The following is the core algorithm content of the present invention:

The first algorithm, time synchronization mechanism: divide time into slot, frame, adjust time and super frame. Each frame contains multiple slots, and each slot can transmit and receive independently. The problem of inability to transmit data due to time imsynchronization between adjacent nodes is solved by changing the size of the superframe in one node while keeping the size unchanged in the other node. Two situations often occur between adjacent parent and child nodes: one is that the superframe of the child node is larger than the superframe size of the parent node. The other is that the superframe size of the parent node is larger than the superframe size of the child node.

For the first case, as shown in Figure 2(a), when the charging rate of the child node is faster than that of the parent node, the size of the child superframe will be smaller than the size of the parent superframe. In this case, we will add another small duty cycle to the end of the existing superframe to extend it. Within this extended duty cycle, the child node will wake up and start to consume the predetermined energy, and then go back to sleep Status and start charging again. Ensure that the energy at the beginning of the duty cycle is equal to the energy at the end, so that the superframe size between the parent and child nodes is equal, and the nodes can ensure time synchronization.

Specific method: It receives a beacon message from the parent node, which contains information about the super frame time of the parent node, which can be used to determine the start time of the parent node's next frame. Now, the child node uses this information and checks how it adjusts its superframe so that its frame start time is aligned with the start time of the parent node. If the superframe size of the parent node is larger than its own superframe, then it decides to extend its superframe. As shown in Figure 3, before the child node receives the beacon message, n*t time has been passed in the frame. T1 is the remaining time in the current frame, and T2 is the sleep time in the duty cycle. T3 is the time occupied by the secondary duty cycle. T3 is divided into Tc and Th, where Tc is the time it takes to consume some energy, and Th is the time it takes to collect the energy. We need to calculate the energy consumption time Tc of the child node.

The formula is derived as follows:

Time T3 is the sum of time Tc and Th, and the time Tparent used by the parent node to start the next frame is the sum of T1, T2, and T3, namely:

T1+T2+T3=Tparent

T1+T2+Tc+Th=Tparent formula 1

Ec=Eh, Tc*Rc=Th*Rh

Putting formula 1 into Th, we get:

In addition, the total time the child node spends in this superframe is equal to the sum of the time the child node has spent, the time remaining in the current awake state, and the time required for the child node to fully charge, namely:

T1+T2+(n*t)=Tchild formula 4

Substituting formula 3 into formula 4 gives:

Finally, we get:

By using formula 5, the child node can expand its superframe to align with the parent node.

For the second case, as shown in Figure 1(b), when the size of the sub-superframe is greater than the size of the parent superframe, the frame size needs to be reduced to achieve synchronization between nodes. The specific method is as follows: The parent node is aligned, and the child node needs to shrink its own duty cycle, as shown in Figure 4. When receiving the beacon information, a child node has passed the n*t time of the frame and left a certain amount of energy. After this energy is left, the child node needs to calculate how long it should continue in the current frame to align itself to the parent node. T1 is the time for the child node to continue the current frame and consume energy, and T2 is the time for the child node to fully charge.

The derivation formula of T1 is as follows:

Known from Figure 4:

T1+T2=Tparent formula 6

When receiving a beacon message from the parent node, the remaining energy (ELeft) in the child node can be calculated from the energy it has consumed in the current frame. This can be expressed by the following formula:

Eleft=Efull-(n*t)*Rc formula 7

The sum of the energy consumed and harvested and the remaining energy of the child node must be equal to the total charge. which is:

Efull=Eleft-(T1*Rc1)+(T2*Rh1) formula 8

Incorporating formula 7 into:

Efull={Efull-(n*t)*Rc}-(T1*Rc1)+(T2*Rh1)

T1*Rc1=(T2*Rh1)-((n*t)*Rc)

Bringing formula 6 into, we get:

T1*Rc1={(Tparent-T1)*Rh1}-((n*t)*Rc)

T1*{Rc1+Rh1}=(Tparent*Rh1)-((n*t)*Rc)

By formula 9, the child node can shrink its superframe to align with the parent node.

The second algorithm, role conversion mechanism: the role conversion mechanism is a more important improvement, a node can simultaneously transmit data with lower or higher layer nodes. As shown in Figure 5(a) below, in order to send data from node 4 to node 2, node 4 must forward the data to node 3. Node 3 stores this data in the buffer, and then passes it to node 2. This is a continuous flow of messages, and messages can be delivered to one node at a time. Therefore, the node must play two different roles, namely the parent node and the child node. First, node 3 acts as a parent node and accepts the data packet of node 4, then switches its role to a child node and forwards the data packet to node 2. In our method, a node can play either of these two roles according to specific conditions. The buffer size of the node is used to determine the role the node needs to play. When the buffer space in the node is free and can accept data from other nodes, the node acts as a parent. Similarly, when the node's buffer is full and cannot accept more data packets, the node will act as a child node. At this time, the child node needs to send data to the parent node to release the buffer space. The threshold for switching from the parent role to the child role is 80% of the full capacity, and the threshold for switching from the child role to the parent role is 10% of the full capacity. The upper threshold is set to reserve a certain buffer to receive your own sensory data, and the lower threshold is set to maximize the transmission of data.

The specific conversion is as follows:

Figure 5(b) shows an example of a node completing role switching in four working cycles. At the beginning, the node fixes a reference point in the time dimension when acting as a parent node. The duty cycle shown in the first row is for reference only to demonstrate the shift of the duty cycle due to frame shift. The duty cycle displayed on the second line is the actual duty cycle used by the node. After a node is converted into a child node, its original child node may still be waiting to communicate with it. At this time, the node needs to record how much its frame has moved to facilitate the exchange back to the state of the original parent node to communicate with the original child node. In the first two working cycles in the figure below, the node is in the child node state, and two-frame shifting is performed to search for the parent node. Then in task cycle 3, prepare to switch to the parent role. Now node needs to calculate the frame displacement it needs in order to readjust itself back to its reference point. The frame displacement is given by Equation 10:

Shift=Minimum Duty Cycle Time-Total Frame Shifts Formula 10

Algorithm pseudo code:

Initialize E0=0, T=1, En=0, H=0, Et={}

Settings: z (the size of the building's force), Eh (the power capacity of the node)

1: loop

2: Obtain the energy E(t) at time t

3: ifE(t)>Eh

4: data acquisition

5: else

6: Continue to collect energy

7:end if

8: Obtain time information of neighbor nodes

9: Calculate the time difference tc

10: Calculate the secondary duty cycle information of the node (formula 5, formula 9)

11: loop:

12: Node data transfer (role conversion)

13: ifHt>z

14: Force imbalance is detected, and the system alarms

15: Let H=0

16: Re-collect force data

17: else

18: Add E(t) to Et

19:end if

20: t=t+1

21:end loop

22:end loop

For the above-mentioned smart pebble, as a monitoring system, the method used for monitoring in the building is divided into three steps in total: the design of the node layout and network routing in the building, the time synchronization and data transmission of the smart pebble node, and the pressure Detect automatic alarm mechanism. Through the design of this structure, the wiring problem in traditional wired sensors and the battery waste problem in wireless sensor networks are effectively solved. Through embedded smart nodes, the real-time force condition of the overall bridge can be detected more realistically, so that bad events (unbalanced force or bridge damage) can be predicted, and emergency events can be dealt with in a timely manner to avoid accidents.

Step 1: Node layout and network routing design in the building:

1.1. Node layout: In this part, the smart pebble node needs to be deployed in the same building surface of the building. The node can be embedded in the building, or the smart pebble can be embedded in the supporting surface of the bridge to evenly deploy the nodes. , The distance between adjacent nodes is kept at a certain size. For example, Figure 6 (a) is a part of the structure of the bridge, (b) shows the intelligent pebble layout diagram of the bridge support, and (c) the intelligent pebble on the road surface of the bridge In the layout map, the smart pebble mainly detects the stress of the bridge support and the bridge span pavement. The bridge support is the main support point. More intelligent pebble nodes will be distributed on the bridge support to obtain the support of the support. For the force situation, the bridge support is divided into two parts, as shown in Figure 6(b). The same smart pebbles are allocated to the left and right parts. By analyzing the forces of the two parts, it is judged whether the support is balanced. The same smart pebbles are equally distributed on the road surface of the bridge. Like the support, it is also divided into two parts. In the later data collection, the force of these two parts will be collected to compare the force of the two parts at the symmetrical position. And compare the force of each node to analyze whether the force of the bridge is balanced.

1.2. Generate network routing: After the node layout is completed, the smart pebble node needs to collect radio frequency signals to store energy. After the node energy storage is completed, the node location technology is used to locate the node, and then the tree network routing is constructed. The data transmission process of the smart pebble is similar to the tree structure, in which data is transmitted from the child node to the parent node, and the parent node transmits the data to the management platform, and the tree routing is easy to expand. As shown in Figure 7(a), this is a route composed of intelligent pebble nodes of a support. Each node is composed of support number-support code-node number, so that you can distinguish which support the network is which For routing, if you need to add more routing, you can add nodes to the child nodes of the routing network, which is easier to expand. As shown in Figure 7(b), this is a route composed of intelligent pebble nodes on a pavement. A bridge is supported by many supports. A section of the road between every two supports forms an intelligent pebble network to establish a route. The number of the pavement-the code of the pavement-the number of the node, so that you can tell where the pavement is on the bridge, and you can quickly find its location when a force warning appears. Finally, all the supports and all the roads form a large network as shown in Figure 7(c), and finally the total route is formed, as shown in Figure 7(d). The force of the entire bridge is analyzed through the data transmitted by each network. . According to the established network route, the node transmits the data to the administrator via the route. For example, as shown in Figure 7, the node in a certain network transmits the data to the network route, and then transmits it through a parent route on the route network, and continues to transmit upward. Finally, it is transmitted to the management platform through the sink node and the Internet, and the management platform makes processing according to the data information.

Step 2:

This part first obtains the state of each node, that is, sleep/wake state and energy usage information. After forming the network, nodes need to know the information of neighboring nodes and obtain it by sending information signals. The operation of the nodes is carried out in the wake-up state. The nodes in the network have their own data transmission slot numbers. Each operation cycle will be allocated according to the number of hops of the routing. First, the intelligent pebble node collects the force information of the building , And then save it to the local cache, sense the synchronization period of the neighbor nodes, perform time synchronization through formula 5 and formula 9, and then judge whether the energy consumed is greater than the remaining energy of the node according to the data size of the node and the distance between the neighbor nodes . Then the node uses the role switching mechanism to transfer data according to the size of the buffer area.

Step 3:

The working process of the early warning indicator light:

This part is mainly an early warning alarm after the analysis of the bridge force. There will be early warning indicators at the entrances of both ends of the bridge and on both sides of each section of the road. The early warning indicator structure is shown in Figure 8. It is composed of a capacitor, an early warning indicator, and smart pebbles. The smart pebbles in this structure are collected by radio frequency signals and converted into electrical energy and stored in the capacitor. When it is detected that the capacity of the capacitor is lower than a certain reserve capacity , Then proceed to energy harvesting, otherwise, enter the dormant state. At the same time, it will receive the analysis results given by the management platform and the warning information of the road network. If the part of the road is overloaded, it will give a light alarm.

Support early warning: Firstly, the intelligent pebble nodes at both ends of the same support collect the force. By comparing the collected force and the pressure that the support can withstand, it is judged whether the force bearing is overloaded, and if the force is too heavy , The overload warning will be uploaded to the management terminal, and the warning indicators at both ends of the support will turn on yellow. If the overload is continued, the warning indicator will turn red, and the data will be uploaded to the management terminal for processing. Balance (within the normal range), the green light is on.

Bridge usage forecast, save the data uploaded by each support network and road network, analyze the data through big data technology, and get the change map of the bridge force, which can predict the service life of the bridge, so that it can be prevented in advance A dangerous accident caused by a bridge that has been used for too long.

The above is only to create preferred specific implementations of the present invention, but the scope of protection created by the present invention is not limited to this. Anyone familiar with the technical field within the technical scope disclosed in the present invention, according to the present invention The created technical solutions and their inventive concepts shall be replaced or changed equivalently, which shall be covered by the protection scope created by the present invention.

Claims

A method for synchronous transmission of pressure collection data distributed at multiple nodes in a building, characterized in that it comprises the following steps:

S1. Deploy nodes in the building and construct network routing;

S2. Obtain the status and energy usage information of each node, realize time synchronization for two adjacent nodes, and transmit data through role conversion.
The method for synchronous transmission of pressure collection data distributed by multiple nodes in a building according to claim 1, wherein the method for arranging nodes is: arranging nodes on the same building surface of the building or arranging nodes on bridges. For multiple areas within the supporting surface, when the same area is laid out, the nodes are equalized, and the distance between adjacent nodes is kept the same; the supporting surface of the bridge includes the supporting surface of the bridge support, the bridge span pavement, and the support of the bridge support More nodes are distributed on the surface. For a node-laying area, there is a symmetrical node-laying area, and the node-laying surface is symmetrical as a whole, so that data comparison can be made on whether the symmetrical area is pressure balanced.
The method for synchronous transmission of multi-node distributed pressure collection data in a building as claimed in claim 2, characterized in that: for the bridge to construct a tree-shaped network route, the method is: a route composed of nodes on the bridge support, each of which is The name of each node is composed of the number of the support-the support code-the number of the node; the bridge has multiple bridge supports, and each road node between two adjacent supports is composed of a route, and the name of each node on it is composed of The number of the road surface-the road surface code-the number of the nodes; all the supports and all the roads form a large network as shown in the figure to form a total route.
The method for synchronous transmission of multi-node distributed pressure acquisition data of a building as claimed in claim 3, characterized in that: the force analysis of the entire bridge by the data transmitted through the network of each bridge support and road surface is based on the established The network routing, the node transmits the data to the management platform through the routing.
The method for synchronous transmission of pressure collection data distributed by multiple nodes in a building according to claim 4, characterized in that: a node in a certain network transmits the data to the network route, and then transmits the data through a parent route on the routing network , Has been transmitted upwards, and finally transmitted to the management platform through the sink node and the Internet for the analysis of the force method.
The method for synchronous transmission of multi-node distributed pressure collection data in a building according to claim 1, wherein the state of each node is acquired, and the state includes sleep/wake state and energy usage state. After forming the network, the node needs to know The information of neighboring nodes is obtained by sending information signals. The operation of the nodes is carried out in the wake-up state. The nodes in the network have their own data transmission slot numbers, and each operation cycle will be allocated according to the number of hops of the route. Perform node data transmission.
The method for synchronous transmission of pressure collection data distributed by multiple nodes in a building according to claim 1, characterized in that: the method of node data transmission is: first the node collects the force information, and then saves it in the local cache, and perceives the synchronization of neighbor nodes Cycle, through time synchronization, according to the data size of the node and the distance between neighboring nodes, determine whether the remaining energy of the current node can meet the energy demand for processing data, and use the role conversion method to perform node data according to whether the buffer data reaches the threshold transmission.
The method for synchronous transmission of pressure collection data distributed across multiple nodes of a building according to claim 1, characterized in that it further comprises step S3. Early warning is carried out after analyzing the stress of the bridge, and the two entrances of the bridge and each section of the road An early warning indicator system is set at the side position, which is mainly composed of an early warning indicator, a capacitor, and a radio frequency signal acquisition module. The radio frequency signal acquisition module collects radio frequency signals and converts them into electrical energy, and connects with the capacitor through the power line to store the electrical energy in the capacitor. Inside, when it is detected that the capacity of the capacitor is lower than a certain reserve, the node will collect energy, and if it is detected that the capacity of the capacitor is full, the node will enter the dormant state, no longer collecting radio frequency signals, the warning indicator system receives the management platform Given the analysis results and the warning information of the road network, if the part of the road is overloaded, a light alarm will be issued.
The method for synchronous transmission of pressure collection data distributed across multiple nodes in a building according to claim 8, wherein the early warning comprises:

Support early warning: force collection at both ends of the same support, by comparing the collected force and the pressure that the support can withstand, to judge whether the force bearing is overloaded, if the force is too heavy, it will be overloaded The warning is uploaded to the management terminal, and the warning indicators at both ends of the support are lit up in yellow. If the load continues to be overloaded, the warning indicator will turn red, and the data will be uploaded to the management terminal for processing. If the other supports are balanced, they will light up. Green light

Road warning: Detect data on the same section of the road. If there is an overload on a certain side of the road or in a certain area, the warning indicators at both ends of the road will turn on yellow. If the overload continues, the red lights will turn on and the data will be uploaded. To the management end processing;

Early warning at both ends of the bridge: If a certain section of the support or road network has continuous stress overload, the warning lights on both sides of the bridge head will be red. The driver can know that the bridge is overloaded according to the warning lights, and then prohibit driving into the bridge to avoid the occurrence of stress overload. The risk of bridge damage caused by force overload.
The method for synchronous transmission of multi-node distributed pressure collection data of a building according to claim 7, characterized in that it also includes bridge usage prediction: save the data uploaded by each support network and road network, and use big data technology to The data is analyzed to obtain a graph of changes in the bridge's stress, predict the service life of the bridge, and prevent dangerous accidents due to the excessively long service life of the bridge in advance.