KR20160041221A - Data Gathering System - Google Patents

Abstract

The present invention relates to a data collecting system including: a plurality of sensor nodes connected with each other through a wireless network, installed in a specific facility and collecting data for a corresponding facility; a data grabber (DG) grabbing information collected from the plurality of sensor nodes; and a control center communicating with the DG and processing real time monitoring and an event occurred in a specific area based on the collected data. The DG and the plurality of sensor nodes exchange a state transition message between the DG and the plurality of sensor nodes, or between the sensor nodes. A network topology is automatically modified and reconstructed corresponding to a fault prediction and the generated fault of the sensor node based on monitoring of the network through exchanging of the state transition message between the DG and the sensor nodes, or between the sensor nodes, thereby stability and fault tolerance of the network can be reinforced.

Description

Data Gathering System

The present invention relates to a data acquisition system.

As science and technology evolve, the phenomenon of automating or performing things through human beings is becoming common. Among them, remote meter reading includes intelligent remote meter reading (AMI) technology to automatically measure usage of water, electricity, gas, etc. used in each home or office without sending meter reading.

Smart water grid (Smart Water Grid) concept that aims to manage water resources with high efficiency by reflecting such intelligent remote meter reading in water industry has been created.

The Smart Water Grid aims at more intelligent water resource management by increasing water resource management efficiency such as water production, transportation, treatment, reuse. Among them, studies on the acquisition of water resources deal with various water resource management problems such as water leakage due to water pipe drainage, water production and transportation energy excess, demand - supply imbalance due to water resources shortage. AMI is a key infrastructure for solving these water management problems. It consists of a metering infrastructure, a communication network capable of bi-directional communication, and a central control center.

The metering infrastructure uses a variety of communication technologies to automate the collection of meter reading data for industrial and household meters. Generally, meter reading data is transmitted to a remote collection device using Power Line Communication (PLC), General Packet Radio Service (GPRS), Radio Frequency (RF), and Wireless Sensor Network (WSN).

Here, the WSN means an ad-hoc type wireless communication network constructed by arranging a plurality of sensor nodes in a physical space. In particular, Zigbee is a WSN constructed by a low-power and low-cost wireless sensor node It is a suitable standard communication protocol and forms a flexible topology according to the layout and operation purpose.

ZigBee network has less physical installation constraints than wired communication such as PLC and unlike wireless communication like RF, there is no restriction of bidirectional communication and expansion of communication range. Because it uses Industrial Scientific Media (ISM) band frequency, GPRS, 3G, LTE Term Evolution.

A prior art related to the remote meter reading technique using a ZigBee network was Korean Patent Laid-Open Publication No. 10-2011-0023585 (published on Mar. 3, 2011).

In the prior art, a sleepy mesh network and a hybrid network perform ZigBee communication at a specific time using a ZigBee network having a hybrid hybrid network and a sleepy mesh network, and thus, a ZigBee router installed in a shaded area, Thereby minimizing power consumption.

However, in the case of the prior art, a solution to the problem of frequency interference where the frequency used by ZigBee overlaps with the frequency band of Wi-Fi and Bluetooth devices and the security problem of the sensor node (the vulnerability of the sensor node operating with limited computing power) I do not present it.

Therefore, it is possible to detect various types of sensor node failure such as software defects, frequency interference, and hardware failure due to physical environment on the data inspection infrastructure composed of the ZigBee network, and to enhance the network stability so that the failure of a specific node does not affect other nodes There is a need for technology development.

An object of the present invention is to provide a technique for enhancing the stability of a network through exchanging state transition messages between sensor nodes constituting a data collection system using a ZigBee network or between sensor nodes and data collectors.

The present invention relates to a wireless communication system including a plurality of sensor nodes connected to each other through a wireless network and installed in a specific facility and collecting data on the facility; A data collector (DG) for collecting information collected from the plurality of sensor nodes; And a control center in communication with the data collector for real-time monitoring based on the collected data and for processing events generated in a specific area; Wherein the data collector and the plurality of sensor nodes exchange a state transition message between the data collector and the plurality of sensor nodes or between the plurality of sensor nodes.

Here, the data collector and the plurality of sensor nodes are connected through a ZigBee network, and the sensor node may determine a relationship between the adjacent sensor node and a parent node (parent node) - a child node (lower node) It is connected by the relationship of different neighboring nodes.

In addition, the relation of the parent node-child node is formed of a tree topology, and forms a data transmission / reception path from the child node toward the parent node toward the data collector.

In addition, the relation of the neighbor nodes is formed by a mesh topology, and forms a data transmission / reception path between neighboring nodes.

Meanwhile, the status transition message is provided as a network initialization message, a network optimization message, a connection information report message, a parent node change message, a failure handling authority delegation message, and a network restoration message.

Here, when the network initialization message is propagated to the plurality of sensor nodes, the sensor nodes form a parent node-child node relationship with one of the neighbor nodes, and form a neighbor node and a neighbor node relationship except the parent node .

In addition, when the network optimization message is propagated to the plurality of sensor nodes, the sensor node transmits its own node relationship information through the parent node in the sensor node at the far end that does not have a child node, And each neighbor node updates its parent node with a parent node with a small number of child nodes.

In addition, the connection information report message includes information for searching for a break point of a network by applying a breakpoint determination algorithm using a depth-first search to a related sensor node as a parent node, its own node, and a neighbor node do.

Here, when data transmission from a specific sensor node to its parent node is impossible, the specific sensor node changes its parent node by transmitting a parent node change message to its neighbor node.

If the sensor node can not transmit data from its own sensor node to its parent node and there is no neighboring node, the specific sensor node transmits a fault delegation authority delegation message to the child node to change the relationship between the parent node and the child node, Delegate authority to child nodes.

Here, when the sensor node receiving the failure handling authority delegation message replaces the data transmission path through the parent node change message and the failure handling authority delegation message, the network recovery message is transmitted to the data collector through its parent node do.

According to the present invention, the network topology is automatically changed and rebuilt in response to the failure of the sensor node and the occurrence of the failure based on the monitoring of the network through the exchange of the state transition message between each sensor node or each sensor node and the data collector Thereby enhancing the stability and fault tolerance of the network.

1 is a block diagram showing a configuration of a data collection system according to the present invention,
Figure 2 is a diagram illustrating a state transition through a state transition message of a sensor node communicating with a data collector according to the present invention,
FIG. 3 (a) is a diagram illustrating network initialization of a sensor node according to the present invention, FIG. 3 (b) is a diagram illustrating network optimization of a sensor node according to the present invention,
FIG. 4 is a diagram showing a disconnecting point among sensor nodes constructed with a ZigBee network,
5 (a) to (c) sequentially illustrate network self recovery through state transition between sensor nodes in a data collection system according to the present invention.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

Prior to this, the terms used in the specification and claims should not be construed in a dictionary sense, and the inventor may, on the principle that the concept of a term can be properly defined in order to explain its invention in the best way And should be construed in light of the meanings and concepts consistent with the technical idea of the present invention.

Therefore, the embodiments shown in the present specification and the drawings are only exemplary embodiments of the present invention, and not all of the technical ideas of the present invention are presented. Therefore, various equivalents It should be understood that water and variations may exist.

FIG. 1 is a block diagram showing the configuration of a data collection system according to the present invention. FIG. 2 is a diagram illustrating a state transition through a state transition message of a sensor node communicating with a data collector according to the present invention. FIG. 3 is a diagram illustrating network initialization of a sensor node according to the present invention, FIG. 3 (b) is a diagram illustrating network optimization of a sensor node according to the present invention, and FIG. And FIGS. 5 (a) to 5 (c) are diagrams sequentially illustrating network self-recovery through state transition between sensor nodes in the data collection system according to the present invention.

The data collection system according to the present invention can be applied to various ZigBee network infrastructures constituting remote meter reading of water, electricity, gas, etc. Hereinafter, a water data collection system for implementing remote water meter reading However, it should be understood that the description does not limit the technical idea of the present invention.

1 to 5, a data collection system according to the present invention includes: a plurality of sensor nodes 10 connected to each other through a wireless network, installed in a specific facility and collecting water resources data for the facility; A water resource data collector (DG) 20 for collecting the water information collected from the plurality of sensor nodes 10; And a water resource control center (30) for communicating with the water data collector (20), for real time monitoring based on the collected water data and for processing events generated in a specific area; Wherein the water data collector 20 and the plurality of sensor nodes 10 are connected to each other through a state transition between the water data collector 20 and the plurality of sensor nodes 10 or a plurality of sensor nodes 10. [ Send and receive messages.

The water data collector 20 collects data generated by the smart water meter including the sensor node 10 in the ZigBee network as a key element of the ZigBee-based remote meter reading infrastructure, and transmits the collected data to the water control center 30.

As shown in FIG. 1, real-time bidirectional communication is performed between the water data collector 20 (hereinafter, referred to as 'WRDG') and the water control center 30 through DDS (Data Distribution Service). DDS is a real-time communication middleware standard established by the Object Management Group (OMG), which publishes and subscribes data exchange units called Topic between publishers and subscribers to exchange information in both directions. can do. The water resource control center 30 receives the water data collected by the WRDG 20 and monitors the flow rate, the hydraulic pressure, and the water quality. In addition, using complex collected water data as input data for complex event processing, information such as leakage and maximum water quantity is derived, thereby enabling highly efficient water resource management.

The smart water meter including the sensor node 10 is a device for measuring water quantity in the water pipe according to the flow of water, and is equipped with a cube sensor.

Flowing Forward signals can be used to detect how much water has flowed into the meter and flow abnormal signals can be detected through the Flowing Backward signal. . In addition, it improves water system maintenance efficiency by generating various types of events such as unauthorized operations such as cable cutting and peak flow occurring due to a small processing capacity of a meter.

Specifies a topic to be exchanged in both directions between the WRDG 20 and the water resource control center 30 using an IDL (Interface Description Language) to exchange data and events between the WRDG 20 and the water resource control center 30. This topic is converted into a topic including a WRDG identifier (ID), a data / event name (Name), and a data / event value (Value) field, and is used for real-time water resource information collection of the water resource management center 30. The raw data and events of the meter reading infrastructure collected by the WRDG 20 are converted into topics and transmitted to the server of the control center through the DDS. DDS supports various QoS (Quality of Service) for exchanging topics. In particular, the deadline attribute ensures real-time topic exchange between the WRDG 20 and the water control center 30. The topic delivered to the water control center 30 can be used for real-time water monitoring, CEP, and machine running to realize water demand response.

ZigBee is a standard that defines high-level communication protocol based on IEEE 802.15.4 standard and is suitable for WSN construction with low-priced wireless sensor nodes. The sensor nodes constituting the ZigBee network are Zigbee Coordinator (ZC) which creates and maintains independent ZigBee network, Zigbee Router (ZR) which extends the physical communication range as an ad hoc form, / Zigbee End Device (ZED) that produces events. In the case of ZC, there is only one per independent ZigBee network, but there may be more than one depending on the physical environment and the purpose of operation, and there are cases where ZR and ZED are not distinguished. In the present invention, the WRDG 20 plays the role of ZC, and the ZR disposed in the metering infrastructure functions to expand the physical communication range. The ZED corresponds to the smart water meter. Hereinafter, ZR and ZED correspond to the sensor node (10).

Each sensor node 10 in the ZigBee network identifies a neighbor node capable of directly communicating with the neighbor node (between the parent node (parent node) and the child node (lower node) ) Relationship.

Each node has zero or one parent node and data delivery in the direction of the parent node is directed to the WRDG 20. A node that is connected in a tightly coupled manner is used as the main data communication path of the WRDG 20 to deliver data and events generated by the smart metering meter to the WRDG 20. Similarly, The neighbor node connected to the WRDG 20 is a candidate node of the parent node for solving a communication problem due to the failure of the next node, and when the parent node fails, one of the neighbor nodes is designated as a new parent node, The sensor node 10 transmits and receives data through a path of a parent-child relationship that is a tree topology and has a network fault tolerance through a path of a neighbor relationship that is a mesh topology. Each sensor node 10 transmits and receives state transition messages, Network configuration, optimization, maintenance, self-recovery, etc. are implemented.

The ZigBee network of the WRDG 20 exchanges the following status transition message between the WRDG 20 and the sensor node 10 or the sensor node 10 for initial network configuration and optimization, network maintenance, and network self recovery.

State transition message

(u) Network Initialization

(v) Network Optimization

(w) Connection Report (Connection Report)

(x) Change the Parent

(y) Handover of Authority

(z) Network Recovery

Each sensor node 10 operating on the basis of the state transition diagram of FIG. 2 exchanges messages (u) to (z) to perform a state transition. (u), (v) message are the network optimization by the initial network configuration and the number of children, (w) the message reports the state of the neighboring node to the WRDG 20 in a normal state to help the network maintenance of the WRDG 20 . (x), (y), and (z) messages are exchanged by exchanging (x) and (y) messages between the sensor nodes 10 as a self recovery message for recovering the loss of the partial network, When the path is found and the self-recovery is completed (z), it is approved by the WRDG (20) through the message and the network is established in a normal state in which communication is possible.

The states of the sensor nodes 10 can be classified into eight states as shown in the following Table 1 according to the relationship with adjacent nodes (including the parent node-child node and the neighbor node). If the eight states are grouped into the same characteristics, As shown in Fig. The five states may be transitioned according to the state transition message communicated by the WRDG 20 or the neighboring node, or may be transitioned according to the result of the action taken by the node itself. For example, the initialization message transmitted by the WRDG 20 establishes connection of all the sensor nodes 10 in the initialization standby network and updates the basic communication path. In addition, when the sensor node 10 having the network self-recovery authority can not find an action to be taken for self-recovery, the state transition may be performed by delegating the processing right to the other sensor node 10.

Parent node Neighbor node Child node ① O O O ② O O X ③ O X O ④ O X X ⑤ X O O ⑥ X O X ⑦ X X O ⑧ X X X

Initializing

As shown in (8), after the sensor node is deployed, no connection with the neighbor node is established. Upon receiving the message Waiting for Initialization (u), one node of the neighboring node is designated as a parent node, and it is possible to distinguish the neighboring node and hold the child node.

Normal

①, ②, ③, ④ state can be normal communication because there is a parent node. If there is no child node in the normal state, (v) message is transmitted from the WRDG 20 to the WRDG 20 from the sensor node 10 located at the terminal end, and the network optimization proceeds after initialization.

Self-healing

The states ⑤, ⑥, ⑦, and ⑧ can not communicate with the WRDG (20) due to a failure of the parent node, resulting in the inability of communication of all lower nodes due to the nature of the tree topology. The node that detected the failure of the parent node has the processing right and designates the neighbor node as the parent node through the message (x) to self-recover the network. However, if there are no neighboring nodes as in (7), (y) sends the message to the child to change the parent relationship and transfer the processing right. This processing privilege delegation is performed only until a child node with an alternative communication path is encountered, so that all the paths of the partial network are not reset and the existing normal path is maintained.

Rejoining

The states ⑤, ⑥ and ⑦ appear not only in the fault processing state but also in the fault processing state. The sensor node (10) which has found a new alternative communication path through self recovery reports the completion of the self recovery to the WRDG (20). If the approval of the WRDG 20 falls, the partial network in which the communication is disconnected returns to a normal state, and the WRDG 20 grasps the changed network topology after self-recovery.

Isolated (Isolated)

⑧ The status can also appear after waiting for initialization. The isolated state is a state in which there is no neighbor or child node to perform the failure processing according to the failure of the parent node, and does not perform any operation until a new neighboring node physically appears. If a new neighbor node is detected, it is changed to the failure processing state and self recovery is attempted.

Initial network configuration and optimization

The ZigBee network constructed by the WRDG 20 and the sensor node 10 initially transmits a (u) message to neighboring nodes in a flooding manner, and each node establishes a connection of parent-child or neighbor relationship between adjacent nodes . 3 (a) shows an example of an initial network configuration. A and B nodes which have received a (u) message from a WRDG 20 designate a WRDG 20 as a parent node, and nodes A and B, (U) to C, D, and E to designate themselves as parents. In case of D node, it is possible to communicate directly with A, C, and B nodes. However, the first node that has transmitted the (u) message is designated as the parent node and the node B has the neighbor relationship. Direct communication is possible but C nodes with the same parent are excluded from the neighbor relationship. In this way, (u) message concatenation of the flooding scheme initializes all nodes of the network to enable basic communication.

The ZigBee network that has been initialized is optimized through the message (v) from the end node to the WRDG (20). (v) The message is passed to the parent-child path and passes the number of its children to the parent node. (v) The node that receives the message informs the neighboring node of the number of its children when the number of its children is updated, so that the neighboring node selects the parent with the smallest number of children. FIG. 3 (b) shows an example of network optimization by the number of children, which shows the change of the parent node of the D node that designated the A node as the parent node after the network initialization. (V) message originating from nodes I, J, and H is delivered along the parent-child path, and the cumulative number of children of nodes A and B is updated so that the number of cumulative nodes of node A and node B is known. As a result, the parent of the D node is changed from the existing A to B, and the number of children of A and B becomes equal to four.

The network optimization according to the number of children who have undergone the initial network configuration increases the lifetime of the entire network by load balancing the sensor node 10 operated with a limited power source.

Network maintenance

The WRDG 20 receives the message (w) containing the connection relationship of each node from the sensor node 10 in the steady state after initial network configuration and optimization. This message can be used to represent the entire ZigBee network as a graph of points and lines. You can draw a graph in the form of a tree through the parent node-child node relationship. You can draw a mesh-type graph by combining the parent node-child node with the neighbor node relation. The WRDG 20 transmits the tree-shaped graph to the control center so that the water system administrator can monitor the ZigBee network configuration in real time. In addition, a mesh-like graph can be utilized for stable network maintenance.

On the other hand, the tree-shaped graph causes deletion of a certain node soon to disconnect the lower node. A tree topology consisting of the parent-child connection of the WRDG (20) means that the failure of a particular node means that all lower nodes are out of communication. At this time, it is possible to recover the network by searching for the alternative route through self-recovery, but self-recovery is not meaningful when the failed node corresponds to the articulation point as shown in E of FIG.

The WRDG (20) draws a directed acyclic graph that connects nodes of parent-child and neighbor relationships with vertices through a message (w), and the direction of the trunk is a parent node . When a breakpoint detection algorithm using depth-first search is applied to a directional bicyclic graph that appears as a mesh, nodes (breakpoints) that have no meaning in self recovery are searched.

The network maintenance of the WRDG 20 through the graph informs the inspection infrastructure manager that the node is in a normal state at present but a node that is a big problem in view of a large network maintenance in case of a failure. System administrators can take additional measures to add stability to the metering infrastructure by additionally installing alternate nodes around the node that corresponds to the breakpoint.

Fault-tolerant

The sensor node 10 constituting the ZigBee network has various types of failures such as hardware failure due to natural disasters, software defects, operation stop due to security problems, intermittent frequency interference, power failure, and the like. In order to maintain a stable ZigBee network, the distributed nodes in the WRDG 20 remove the faulty node through collaboration and set up a new network path to normalize the network.

Network self-recovery between the sensor nodes 10 is initiated when a failure of the parent node is detected. The sensor node 10 whose parent has disappeared immediately sends a message (x) to one of the neighbor nodes to designate the parent node to recover the network. However, in the absence of a neighboring node, the alternate path for network recovery is likely to be the neighbor of the child nodes, so (y) sends the message to the child node to change the parent-child relationship and delegate the processing authority. When this process occurs in a cascade and finally finds an alternative route (z), it sends a message to the WRDG 20 to inform the network normalization through self recovery.

5 (a) to 5 (c) show an example of restoring the network through cooperation between the sensor nodes 10, in which communication failure of the lower node including the nodes D and E occurs due to the failure of the node B (see FIG. 5 a)) In case of D node, A, which is a neighbor node, is designated as a parent node, and the networks of D and G nodes return to normal. At this time, the G-node has no network changes. Meanwhile, since the E node does not have a neighboring node, H is transferred to the child node and the parent-child relation is transferred and the fault handling authority is transferred (FIG. 5 (b) (Fig. 5 (c)). After that, the WRDG 20 updates the changed network topology according to the failure of the B node through the (w) message.

As described above, the network self recovery based on the example of FIG. 5 (a) to FIG. 5 (c) and the state transition diagram of FIG. 2 is advantageous in that it partially changes only the entire topology of the disconnected partial network based on the fault node.

As described above, the data collecting system according to the present invention can be used to predict a failure of a sensor node based on monitoring of a network through exchanging state transition messages between sensor nodes or between each sensor node and a data collector, The network topology can be automatically changed and rebuilt to enhance the stability and fault tolerance of the network.

While the present invention has been described with reference to the exemplary embodiments and the drawings, it is to be understood that the technical scope of the present invention is not limited to these embodiments and various changes and modifications may be made without departing from the spirit and scope of the present invention by those skilled in the art. Various modifications and variations may be made without departing from the scope of the appended claims.

Description of the Related Art [0002]
10: Sensor node
20: Data Collector
30: Control Center

Claims (11)

A plurality of sensor nodes connected to each other through a wireless network, installed in a specific facility and collecting data on the facility;
A data collector (DG) for collecting information collected from the plurality of sensor nodes; And
A control center in communication with the data collector for real time monitoring based on the collected data and for processing events generated in a specific area; / RTI >
The data collector and the plurality of sensor nodes exchange a state transition message between the data collector and the plurality of sensor nodes or between the plurality of sensor nodes.
Data acquisition system. The method according to claim 1,
The data collector and the plurality of sensor nodes are connected via a ZigBee network, and the sensor node may be arranged such that the relationship between the adjacent sensor node and the parent node (parent node) - the child node (lower node) Neighboring nodes.
Data acquisition system. 3. The method of claim 2,
Wherein the relationship between the parent node and the child node comprises a tree topology and forms a data transmission / reception path from the child node toward the parent node toward the data collector
Data acquisition system. 3. The method of claim 2,
Wherein the relationship of the neighboring nodes is configured with a mesh topology to form a data transmission / reception path between neighboring nodes
Data acquisition system. 3. The method of claim 2,
Wherein the status transition message is provided as a network initialization message, a network optimization message, a connection information report message, a parent node change message, a failure handling authority delegation message, and a network recovery message
Data acquisition system. 6. The method of claim 5,
When the network initialization message is propagated to the plurality of sensor nodes, the sensor nodes form a parent node-child node relationship with one of the neighbor nodes, and form a neighbor node-neighbor relationship except the parent node To
Data acquisition system. The method according to claim 6,
When the network optimization message is propagated to the plurality of sensor nodes, the sensor node transmits the node relationship information of its own node through the parent node, and transmits the transmitted node relation information to the neighboring node , Each neighboring node is arranged to update a parent node with a parent node having a small number of child nodes
Data acquisition system. 6. The method of claim 5,
The connection information report message includes information for searching for a break point of a network by applying a breakpoint determination algorithm using Depth-First Search to a related sensor node as a parent node, its own node, and a neighboring node Featured
Data acquisition system. 6. The method of claim 5,
When it is impossible to transmit data from a specific sensor node to its parent node, the specific sensor node transmits a parent node change message to its neighbor node to change its parent node
Data acquisition system. 10. The method of claim 9,
If the sensor node can not transfer data from its own sensor node to its parent node and there is no neighboring node, the specific sensor node transmits a fault delegation authority delegation message to the child node to change the relationship between the parent node and the child node, To a child node
Data acquisition system. 11. The method of claim 10,
When the sensor node having received the failure processing authority delegation message transmits a network recovery message to the data collector through its parent node when the data transmission path is replaced through the parent node change message and the failure handling authority delegation message Featured
Data acquisition system.

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