CN107113548B - Train monitoring device and monitoring method based on power state - Google Patents
Train monitoring device and monitoring method based on power state Download PDFInfo
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- CN107113548B CN107113548B CN201580072182.6A CN201580072182A CN107113548B CN 107113548 B CN107113548 B CN 107113548B CN 201580072182 A CN201580072182 A CN 201580072182A CN 107113548 B CN107113548 B CN 107113548B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L67/00—Network arrangements or protocols for supporting network services or applications
- H04L67/01—Protocols
- H04L67/12—Protocols specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W24/00—Supervisory, monitoring or testing arrangements
- H04W24/02—Arrangements for optimising operational condition
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
- H04W4/70—Services for machine-to-machine communication [M2M] or machine type communication [MTC]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/02—Power saving arrangements
- H04W52/0209—Power saving arrangements in terminal devices
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/51—Allocation or scheduling criteria for wireless resources based on terminal or device properties
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
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Abstract
A train monitoring apparatus based on a power status according to the present invention includes: one or more wireless sensor units for periodically measuring an operational state of the train and generating sensor data; one or more autonomous power supply units for generating power by using vibration energy of a train, supplying the generated power to the wireless sensor unit, monitoring the generated power, and transmitting power status information to a communication control unit; and the communication control unit for controlling the configuration of the wireless link of the wireless sensor unit based on the power status information so as to allocate any one of a dedicated channel and a contention channel thereto, and transmitting the sensor data received from the wireless sensor unit to an external communication network.
Description
Technical Field
The following description relates to a wireless sensor network for safe train operation that measures the operating state of devices in a train, and more particularly to techniques for controlling the operation of a wireless sensor network that monitors a train by using an energy harvester.
Background
As a method for safe train operation, a wireless sensor network has been used, which measures the operation state of devices in a running train in real time so that, in an abnormal situation, the train concerned can be repaired immediately. For safe train operation, the wireless sensor network may transmit the operating state of the train in real time by using an energy harvester, in which power may be generated from vibration energy of the train without using an external power source.
However, when an energy harvester using vibration energy of a train is used, the power supply may vary depending on the operating state of the train, so that there is a need for a method of ensuring stable power supply. In order to provide stable power, a method of using a super capacitor in a power generation device has been used, but the method may cause degradation of link quality in a wireless sensor due to discharging and charging caused by imbalance between generated power and power consumed in a communication module of the wireless sensor. In particular, in a case where the wireless link is disconnected due to insufficient power while the wireless sensor is operating, the link should be re-established between the wireless sensor and the coordinator after power sufficient to enable communication is supplied, thereby requiring additional power consumption and causing a delay in transmission of sensor data, which then results in deterioration of communication quality.
Korean patent No. 10-0877587 discloses a method for detecting vibration and the position of vibration generated when operating a high-speed train and transmitting the same to a control server. However, this method discloses only transmitting detected information by wireless communication, and does not have any solution to the problem of stabilizing the power supply or deterioration of communication quality.
Disclosure of Invention
Technical problem
An object of the present invention is to provide a train monitoring apparatus and method based on a power state in which a wireless sensor network monitors a train by using an energy harvester so that irregular power generation does not cause deterioration of communication quality.
Technical scheme
In one general aspect, there is provided a train monitoring apparatus based on a power state, the apparatus including: one or more wireless sensors configured to generate sensor data by measuring an operating state of the train at predetermined intervals; one or more autonomous power sources configured to generate power by using vibration energy of the train, supply the generated power to the one or more wireless sensors, and transmit power status information generated by monitoring the supplied power to the communication controller; and the communication controller configured to control the wireless link to allocate a dedicated channel or a contention channel to the one or more wireless sensors based on the power status information and to transmit sensor data received from the one or more wireless sensors through the external communication network.
The communication controller may construct a superframe by allocating channels and transmission intervals to the one or more wireless sensors based on the power status information. The communication controller may determine, based on the power status information, whether the power status of the one or more wireless sensors reaches a threshold at which to change a method of establishing a wireless link. Further, the communication controller may allocate a contention channel to a wireless sensor having a power status equal to or greater than a method determination threshold among the one or more wireless sensors. In addition, the communication controller may allocate a dedicated channel to a wireless sensor having a power state lower than a method determination threshold among the one or more wireless sensors. In order to provide a charging time to a wireless sensor having a power state equal to or lower than a transmission interval extension threshold among one or more wireless sensors having a power state lower than a method determination threshold, the communication controller may change a sampling frequency by allocating a dedicated channel having an extended transmission interval to the wireless sensor.
In another general aspect, there is provided a train monitoring method using a train monitoring apparatus based on a power status, the method including: supplying power generated by using vibration energy of the train to one or more wireless sensors, and generating power status information to a communication controller by monitoring the power supplied to the one or more wireless sensors; and allocating a dedicated channel or a contention channel to the one or more wireless sensors based on the power status information. The method then includes transmitting the sensor data received from the one or more wireless sensors over an external communication network.
The allocating of the dedicated channel or the contention channel includes allocating the contention channel to a wireless sensor having a power status equal to or greater than a method determination threshold among the one or more wireless sensors. Further, the step of allocating a dedicated channel or a contention channel includes allocating a dedicated channel to a wireless sensor having a power status below a method determination threshold among the one or more wireless sensors. In order to provide a charging time to a wireless sensor having a power state equal to or lower than a transmission interval extension threshold among one or more wireless sensors having a power state lower than a method determination threshold, the communication controller may change a sampling frequency by allocating a dedicated channel having an extended transmission interval to the wireless sensor.
Advantageous effects
The train monitoring apparatus and method based on power status uses a train wireless sensor network that acquires an operation status in real time from a sensor attached to a train vehicle, wherein transmission quality and an operation period of a wireless sensor can be increased by changing a setting mode of a wireless link in the wireless sensor network based on a status of generated power of the wireless sensor. Further, in the train monitoring apparatus and method based on the power state, the power state of the wireless sensor in the wireless sensor network is managed, thereby preventing unnecessary operation of the wireless sensor and power consumption caused by generation of an interference signal.
Drawings
Fig. 1A and 1B are block diagrams illustrating a train monitoring apparatus 100 based on a power status according to an exemplary embodiment.
Fig. 2 is a diagram illustrating a communication controller 200 of a train monitoring apparatus based on a power state according to an exemplary embodiment.
Fig. 3 is a diagram illustrating a superframe of the communication controller 200 according to an exemplary embodiment.
Fig. 4 is a diagram illustrating another example of the train monitoring apparatus 100 based on a power state according to an exemplary embodiment.
Fig. 5 is a block diagram illustrating a format of power status information of the train monitoring apparatus 100 based on a power status according to an exemplary embodiment.
Fig. 6 is a block diagram illustrating another format of power status information of the train monitoring apparatus 100 based on a power status according to an exemplary embodiment.
Fig. 7 is a flowchart illustrating a method of autonomously establishing a wireless link of a train monitoring device based on a power status according to an exemplary embodiment.
Fig. 8 is a flowchart illustrating an operation of a sensor node in a method of autonomously establishing a wireless link of a train monitoring device based on a power state according to an exemplary embodiment.
Detailed Description
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. Terms used throughout this specification are defined in consideration of functions in the embodiments of the present disclosure, and may vary according to user or manager's intention, or convention, and the like. Therefore, the meanings of the terms used in the following examples should be followed by definitions, if any, herein. Otherwise, the terms used herein should be construed to have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
Fig. 1A and 1B are block diagrams illustrating a train monitoring apparatus 100 based on a power status according to an exemplary embodiment.
Referring to fig. 1A and 1B, a train monitoring apparatus 100 based on a power state is installed in a train to monitor an operation state of the train and transmit the monitored state to a sensor monitoring center 10. Further, the train monitoring apparatus 100 based on the power state generates power from vibration energy generated during train operation by using an energy harvester to operate a sensor sensing an operation state of the train. The train monitoring device 100 based on power status includes one or more wireless sensors 110, one or more autonomous power sources 120, and a communication controller 130.
The wireless sensors 110 include sensors that measure temperature and vibration, and may measure heating and vibration of a plurality of bearings mounted on the axles of a rail vehicle bogie (bogie) to generate sensor data based on these measurements. In addition, the wireless sensor 110 may transmit sensor data to the communication controller 130 over a wireless link established by the communication controller 130. The communication between the wireless sensor 110 and the communication controller 130 may be performed through a wireless sensor network such as ZigBee communication based on IEEE 802.15.4 standard, which is a low power, low speed, and near field wireless communication standard.
The autonomous power source 120 may generate (generate) electric power by using vibration energy generated during operation of the train, wherein many vibrations may be generated while the train is moving. Autonomous power source 120 may generate power from such vibrations by harvesting using piezoelectric energy.
Additionally, the autonomous power source 120 may monitor the power supplied to the wireless sensor and/or the power generated by the vibrational energy. Since the train does not travel at a constant speed or acceleration, the power generated by the autonomous power source 120 may vary depending on the acceleration of the traveling train. Accordingly, the present disclosure provides an autonomous power supply 120 that can generate power status information by continuously monitoring the power status, thereby enabling the wireless sensor 110 to establish a wireless link in consideration of the status of the generated power. The power status information may include the amount of power generated from the main power source 120, as well as changes in the amount of power. Further, the autonomous power source 120 may transmit the generated power status information to the communication controller 130, and may supply the generated power to the wireless sensor 110 to operate the wireless sensor 110.
The communication controller 130 may form a Wireless Sensor Network (WSN) with one or more wireless sensors 110 via wireless links. To this end, the communication controller 130 may establish a wireless link for the one or more wireless sensors 110 based on the power status information received from the autonomous power source 120, and may receive sensor data from the one or more wireless sensors 110 through the established wireless link.
The power status information may include the amount of power generated from the main power source 120, as well as changes in the amount of power. The autonomous power source 120 generates electric power from vibration energy generated during operation of the train by using the energy harvester, and the electric power generated thereby may vary depending on the acceleration of the running train. Accordingly, the communication controller 130 checks the state of the power generated from the main power source 120 based on the power state information, and may establish or change the wireless link of the wireless sensor 110 according to the power state. In addition, the communication controller 130 may change the measurement period of the wireless sensor 110.
The communication controller 130 may include a gateway 131 and one or more coordinators 132 to establish a wireless sensor network. The one or more coordinators 132 may establish a wireless link for the wireless sensors 110 based on the power status information, may collect sensor data from the wireless sensors 110, and may transmit the collected sensor data to the gateway 131. The coordinator 132 may transmit the sensor data directly to the gateway 131, or may transmit the sensor data to the gateway 131 via other coordinators 132 located nearby or at a certain level. The gateway 131 may transmit the sensor data received from the one or more coordinators 132 to the sensor monitoring center 10, and the one or more wireless sensors 110 are connected to the coordinator 132 having a high radio wave intensity among the one or more coordinators 132.
Communication between the one or more coordinators 132, and between the coordinators 132 and the wireless sensors 110, may be performed using various wireless communication methods, including a near field wireless communication standard (IEEE 802.15.4 standard), such as ZigBee communication, or a wireless LAN standard (IEEE 802.11), such as Wi-Fi. In addition, the communication between the gateway 131 and the sensor monitoring center 10 may be performed through a mobile communication network.
One or more wireless sensors 110 may be disposed on the axle of the rail vehicle bogie or on the axle edge (periply) of the rail vehicle bogie to measure heating and vibration. One or more autonomous power sources 120 may also be arranged on the axle edge of the rail vehicle bogie to generate electrical power. Further, the wireless sensor 110 is operated by power generated from the main power supply 120. One wireless sensor 110 and one autonomous power source 120 operating on the same axle of the rail vehicle may operate as a pair.
That is, the communication controller 130 may control the wireless sensor 110 and the autonomous power source 120 arranged on the same axle edge of the rail vehicle as a pair. For example, for the first wireless sensor 111 and the first power source 121, the communication controller 130 may determine the measurement period of the wireless link and the first wireless sensor 111 based on the power state of the first power source 121.
By considering the amount of generated power based on the power state information, the communication controller 130 may perform the following operations to reduce power consumption of the wireless sensor 110, which is a low power wireless sensor. The communication controller 130 may assign a dedicated channel to the wireless sensor 110 that transmits sensor data at predetermined intervals. Further, in the case where there is a small amount of sensor data or the wireless sensor 110 having a long transmission interval has a good power state, the communication controller 130 allocates a channel of the contention mode to the wireless sensor 110. Further, the communication controller 130 sets channel mode transition to prevent the wireless sensor having a poor power state from occupying a dedicated channel for a long period of time.
In addition, the communication controller 130 may determine a period of the superframe based on the power level of the wireless sensor 110, and may estimate a charging time of the sensor node to determine a period of time during which the dedicated channel is maintained. In the case where a wireless sensor 110 having a very poor power state is identified, the communication controller 130 cancels the dedicated channel allocation mode for the wireless sensor 110. Further, in the case where the wireless sensor 110 returns to the good power state, the communication controller 130 may set CSMA-CA for the wireless sensor 110. A method of establishing a wireless link in the communication controller 130 will be described later in further detail.
Further, the communication controller 130 may change the sampling frequency of the wireless sensor 110 by considering the power state of the wireless sensor 110 based on the power state information. In response to the communication controller 130 considering that the power state of the wireless sensor 110 is not greater than the threshold value of the extended transmission interval (hereinafter referred to as a transmission interval extension threshold value) based on the power state information, the train monitoring apparatus based on the power state determines that the current power state is insufficient to enable communication, and allocates a dedicated channel having the extended transmission interval during which the sampling frequency varies so that the wireless sensor 110 can have a time to charge. The extended transmission interval means a transmission interval longer than the basic transmission interval.
Fig. 2 is a diagram illustrating a communication controller 200 of a train monitoring apparatus based on a power state according to an exemplary embodiment.
Referring to fig. 2, the communication controller 200 of the train monitoring apparatus based on the power state includes an application layer 210, a MAC layer 220, and a physical layer 230 for determining a wireless link connection method. Further, the application layer for determining the wireless link connection may include a wireless sensor power state manager 211, a superframe constructor 212, a wireless link connection method determiner 213.
The wireless sensor power status manager 211 identifies the status of power generated by one or more autonomous power sources 120 based on power status information received from each autonomous power source 120. Further, the wireless sensor power status manager 211 may determine a channel link for the wireless sensor 110 according to the power status. The wireless link includes a contention-based Contention Access Period (CAP) and a non-contention-based contention-free period (CFP). CAP is a period of contention for a channel in which carrier sense multiple access collision avoidance (CSMA-CA) is used, thereby increasing power consumption of the wireless sensor 110 and causing transmission latency. Further, the CFP is a period of a dedicated channel in which the wireless sensor 110 can transmit data at low power in the case of transmitting data at regular intervals.
The wireless sensor power status manager 211 may determine dedicated channel links (GTs) or contention channel links (CSMA-CA) based on the power status of each wireless sensor 110. In response to a determination that the power status of any one of the wireless sensors is sufficient, the wireless sensor power status manager 211 may allocate a contention-based channel (contention channel link), whereas in response to a determination that the power status of any one of the wireless sensors is insufficient, the wireless sensor power status manager 211 allocates a dedicated channel link and may adjust the transmission interval according to the power status.
The superframe constructor 212 may construct superframes for the wireless sensors 110 according to the channel links and periods determined by the wireless sensor power status manager 211. Further, the superframe constructor 212 may transmit the constructed superframe to the wireless sensor 110. The structure of the superframe will be further described with reference to fig. 3.
The wireless link connection method determiner 213 may determine the wireless link connection method based on the determinations of the wireless sensor power state manager 211 and the superframe constructor 212.
Fig. 3 is a diagram illustrating a superframe of the communication controller 200 according to an exemplary embodiment.
Referring to fig. 1B and 3, the communication controller 130 may form a superframe 310 corresponding to each wireless sensor 110 according to a channel link and a period determined based on the power state information. The wireless link includes a contention-based Contention Access Period (CAP) and a non-contention-based contention-free period (CFP).
CAP is a period of contention for a channel in which carrier sense multiple access collision avoidance (CSMA-CA) is used, thereby increasing power consumption of the wireless sensor 110 and causing transmission latency. Further, the CFP is a period of a dedicated channel in which the wireless sensor 110 can transmit data at low power in the case of transmitting data at regular intervals. That is, in the wireless link of the wireless sensor 110, in the case where the power is equal to or greater than the predetermined determination method threshold, i.e., the power is sufficient, a contention channel period (CAP) is allocated, and in the case where the power is lower than the predetermined determination method threshold, i.e., the power is insufficient, the interval is adjusted to allocate a dedicated channel period (CFP). The superframe is suitable for a low power sensor network because the superframe includes an active part (CAP + CFP) during which communication between the wireless sensor 110 and the coordinator 132 of the communication controller 130 is performed, and a stop part during which the wireless sensor 110 is not operated. In the case where CFP is used, each wireless sensor 110 to which a dedicated channel (time slot) is allocated may transmit sensor data to the coordinator 132.
Fig. 3 illustrates an example in which the wireless sensor waits until charging when the first sensor (#1) has a low power level. Therefore, in fig. 3, when the first sensor (#1) of the wireless sensor 110 transmits sensor data over two superframes in the CFP 312, the data is transmitted after the basic transmission interval and the extended transmission interval in the same CFP slot.
Fig. 4 is a diagram illustrating another example of a train monitoring apparatus 400 based on a power state according to an exemplary embodiment.
Referring to fig. 4, the train monitoring apparatus 400 based on the power status includes one or more sensor nodes 410 and a communication controller 420. The sensor node 410 includes a wireless sensor 411, an autonomous power supply 412, and a wireless communicator 413. The number of sensor nodes 410 may be determined randomly, which may be the number of axles of the bogie. In fig. 4, one sensor node 410 is illustrated for convenience of explanation.
A wireless sensor 411 and an autonomous power supply 412 are included as a pair so that the communication controller 420 is connected to a wireless link through the wireless communicator 413. Further, the wireless sensor 411 and the autonomous power supply 412 may be connected to the wireless communicator 413 through a wired connection (direct connection).
The wireless sensor 411, which operates using power supplied from the main power source 412, may generate sensor data by measuring the temperature and vibration of the axle of the bogie, and may transmit the generated sensor data to the communication controller 420 through the wireless communicator 413. The autonomous power supply 412 may generate power by using vibration energy generated during train operation and supply the generated power to the wireless sensor 411. In addition, the autonomous power supply 412 generates power status information by monitoring the generated power, and transmits the power status information to the communication controller 420 through the wireless communicator 413.
The sensor data received from the wireless sensor 411 and the power status information received from the autonomous power supply 412 are transmitted to the communication controller 420 through the wireless communicator 413. The communication controller 420 may identify the power state of the wireless sensor 411 based on the received power state information, and may allocate a channel corresponding to the wireless sensor 411 and set a transmission interval by considering the power state information. The wireless communicator 413 may transmit the sensor data of the wireless sensor 411 to the communication controller 420 through a wireless link determined by the communication controller 420.
Fig. 5 is a block diagram illustrating a format of power status information of the train monitoring apparatus 100 based on a power status according to an exemplary embodiment.
Referring to fig. 1A and 5, fig. 5 illustrates power status information including a MAC management message of the IEEE 802.15.4 standard. The communication controller 130 or the coordinator 132 of the communication controller 130 may acquire power status information (status of supplying power) by adding a "power status request" and a "power status response" to the MAC management message of the existing IEEE 802.15.4 standard. In this case, the coordinator 132 transmits a request for power status information ("power status request") to the autonomous power source 120 in fig. 1A or the sensor node 410 in fig. 4. Then, in response to the "power status request", the autonomous power source 120 or the sensor node 410 transmits a "power status reply" to the communication controller 130. The power status request message includes in payload 510 a minimum power level, a maximum power level, and a number of power steps between the minimum power level and the maximum power level.
Fig. 6 is a block diagram illustrating another format of power status information of the train monitoring apparatus 100 based on a power status according to an exemplary embodiment.
Referring to fig. 1 and 6, the power status information represents a data frame used when the sensor node 410 or the autonomous power source 120 transmits the power status information to the communication controller 130 or the coordinator 132. Using the data frame format, the sensor node 410 may transmit sensor data and power status information simultaneously in the form of piggyback transmissions (piggybacks). To this end, the type of data is specified for the power status information, and the power status information includes a field representing piggyback transmission status information. The method may be adapted to situations where sensor data is transmitted at regular intervals.
In an exemplary embodiment, the coordinator 132 may transmit a power state request message to the sensor node 410 or the autonomous power source 120 by using the MAC management message in order to manage the power state of the sensor node 410 or the autonomous power source 120, wherein the coordinator 132 may designate the power state of the wireless sensors 110 and 411 as a minimum value, a maximum value, and a power step size in the power state request message.
Upon receiving the power status request message from the coordinator 132, the sensor node 410 or the autonomous power source 120 transmits power status information including a power step, which is classified by using a data frame, to the communication controllers 130 and 420 or the coordinator 132.
Fig. 7 is a flowchart illustrating a method of autonomously establishing a wireless link of a train monitoring device based on a power status according to an exemplary embodiment.
Referring to fig. 7, a method of autonomously establishing a wireless link of a train monitoring apparatus based on a power status includes: collecting power status information in S701; and checking a power state of the wireless sensor in S702. In the present disclosure, the wireless sensor operates using power generated using vibration energy generated during train operation. However, since the state of the generated power may frequently change according to the acceleration of the running train, it may affect the operation of the wireless sensor and the performance of the wireless link. In the present disclosure, a wireless link is established based on the power status of the wireless sensor identified by checking the power status information.
Once the power state of the wireless sensor is identified, the power state based train monitoring device may compare the identified power state to the method determination threshold to determine whether the power state is below the method determination threshold at S703. The method determination threshold is a reference value that distinguishes between the contention channel and the dedicated channel. The train monitoring apparatus based on the power state compares the power state of the wireless sensor with the method determination threshold to determine whether the power state of the wireless sensor reaches a threshold that can change the method of establishing the wireless link. In the case where the power status of the wireless sensor is greater than the predetermined method determination threshold, the train monitoring device based on the power status determines that the power status of the wireless sensor reaches a sufficient power level (available power is sufficient), and assigns a contention Channel (CAP) to the wireless sensor at S704. The CAP is suitable for a case where the power level is sufficiently high, or a case where a wireless sensor is not required to periodically transmit sensor data (sensor data is continuously transmitted).
At the time of the comparison in S703, in the case where the power state of the wireless sensor is lower than the predetermined method determination threshold value, the train monitoring apparatus based on the power state determines that the power state of the wireless sensor reaches the method determination threshold value. Then, the train monitoring apparatus based on the power state compares the power state of the wireless sensor with the transmission interval expansion threshold to determine whether the transmission interval of the wireless sensor needs to be expanded at S705. In the case where the power state of the wireless sensor is equal to or lower than the transmission interval extension threshold, the train monitoring apparatus based on the power state determines that the current power state may not enable communication, and allocates an extended transmission interval for a dedicated channel in order to provide a charging time to the wireless sensor in S706. The extended transmission interval means a transmission interval longer than the basic transmission interval.
In the case where the power state of the wireless sensor is greater than the transmission interval expansion threshold in S705, the current power state is considered to be sufficient for communication, and the train monitoring apparatus based on the power state allocates a basic transmission interval for a dedicated channel in S707. According to the channels allocated in S704, S706, and S707. The train monitoring apparatus based on the power status constructs a superframe in S708. The constructed superframe is transmitted to a wireless sensor or sensor node to establish a wireless link between the wireless sensor and the communication controller.
Fig. 8 is a flowchart illustrating an operation of a sensor node in a method of autonomously establishing a wireless link of a train monitoring device based on a power state according to an exemplary embodiment.
Referring to fig. 8, a method of autonomously establishing a wireless link according to an exemplary embodiment may solve the problem of power of a wireless sensor by changing a sampling frequency of the wireless sensor based on a power state. The train monitoring apparatus based on the power status collects power status information in S801 and checks the power status of the wireless sensor in S802. Then, the train monitoring device based on the power state compares the power state with a threshold value available for communication (hereinafter referred to as a communication available threshold value) to determine whether the power state of the wireless sensor exceeds the communication available threshold value in S803. The communication availability threshold represents a minimum power that enables the wireless sensor to transmit a communication. In the case where the power state is not greater than the communication available threshold, the train monitoring apparatus based on the power state determines that communication is not available, and causes the wireless sensor to enter a sleep mode in S804. The wireless sensor that has entered the sleep mode waits until its power state returns to a good state.
In the case where the power state of the wireless sensor is greater than the communication available threshold in S803, the train monitoring apparatus based on the power state compares the power state with the sampling threshold to determine whether the power state exceeds the sampling threshold in S805. The sampling threshold value represents a threshold value of a sampling frequency with which the wireless sensor measures the state of the train. The train monitoring apparatus based on the power state compares the power state and the sampling frequency to determine whether the communication is unstable.
In the case where the power state is equal to or lower than the sampling threshold in S805, the train monitoring apparatus based on the power state determines that the power state of the wireless sensor can enable communication but is unstable, and reduces the measurement speed of the wireless sensor in S806. Then, the train monitoring apparatus based on the power status transmits the sensor data in S807. In the case where the power state exceeds the sampling threshold in S805, the train monitoring apparatus based on the power state determines that the power state may enable communication but is unstable, and transmits the sensor data without changing the sampling speed.
As illustrated in fig. 7 and 8, the method of autonomously establishing a wireless link of the train monitoring device based on the power state is individually performed for each of one or more wireless sensors or each of one or more sensor nodes included in the train monitoring device based on the power state. In this way, by establishing a wireless link with an individual wireless sensor according to the power state of each wireless sensor, the train monitoring apparatus based on the power state can actively respond to a change in the power state, thereby preventing deterioration of the communication quality.
The exemplary embodiments described above may be written as computer programs. In addition, codes and code segments required for implementing these computer programs can be easily derived by computer programmers in the art. Further, the written program may be stored in a recording medium or an information storage medium, and may be read and executed by a computer system to implement the present invention. The recording medium may include all types of computer-readable recording media.
A number of examples have been described above. Nevertheless, it will be understood that various modifications may be made. For example, suitable results may be achieved if the described techniques are performed in a different order and/or if components in a described system, architecture, device, or circuit are combined in a different manner and/or replaced or supplemented by other components or their equivalents. Accordingly, other implementations are within the scope of the following claims.
Claims (7)
1. A train monitoring apparatus based on power status, the apparatus comprising:
one or more wireless sensors configured to generate sensor data by measuring an operating state of the train at predetermined intervals;
one or more autonomous power sources configured to generate power by using vibration energy of the train, supply the generated power to the one or more wireless sensors, and transmit power status information generated by monitoring the supplied power to the communication controller; and
the communication controller configured to control a wireless link to assign a dedicated channel or a contention channel to the one or more wireless sensors based on the power status information,
wherein the communication controller allocates a contention channel to a wireless sensor having a power status equal to or greater than a method determination threshold among the one or more wireless sensors, and wherein the communication controller allocates a dedicated channel to a wireless sensor having a power status lower than the method determination threshold among the one or more wireless sensors.
2. The apparatus of claim 1, wherein the communication controller constructs the superframe by allocating a channel and a transmission interval to the one or more wireless sensors based on the power status information.
3. The apparatus of claim 1, wherein to provide the charging time to a wireless sensor having a power status equal to or lower than a transmission interval extension threshold among the one or more wireless sensors having a power status lower than the method determination threshold, the communication controller changes the sampling frequency by allocating a dedicated channel having an extended transmission interval to the wireless sensor.
4. The apparatus of claim 1, wherein the communication controller transmits a power status request message including a minimum power, a maximum power, and a power step size by using the MAC management message; and
the one or more autonomous power sources transmit power status information including power steps, classified by using data frames, to the communication controller based on the received power status request message.
5. The device of claim 1, wherein the communication controller communicates sensor data received from the one or more wireless sensors to an external communication network.
6. A train monitoring method using a train monitoring apparatus based on a power status, the method comprising:
supplying power generated by using vibration energy of the train to one or more wireless sensors and generating power status information to a communication controller by monitoring the power supplied to the one or more wireless sensors; and
allocating a dedicated channel or a contention channel to the one or more wireless sensors based on the power status information,
wherein the communication controller allocates a contention channel to a wireless sensor having a power status equal to or greater than a method determination threshold among the one or more wireless sensors, and wherein the communication controller allocates a dedicated channel to a wireless sensor having a power status lower than the method determination threshold among the one or more wireless sensors.
7. The method of claim 6, wherein in the allocating dedicated channel or the contention channel, in order to provide a charging time to a wireless sensor having a power status equal to or lower than a transmission interval extension threshold among one or more wireless sensors having a power status lower than a method determination threshold, the communication controller changes a sampling frequency by allocating a dedicated channel having an extended transmission interval to the wireless sensor.
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| KR10-2014-0164733 | 2014-11-24 | ||
| KR20140164733 | 2014-11-24 | ||
| KR1020150145004A KR102083272B1 (en) | 2014-11-24 | 2015-10-16 | Apparatus and method for train monitoring based power state |
| KR10-2015-0145004 | 2015-10-16 | ||
| PCT/KR2015/011571 WO2016085141A1 (en) | 2014-11-24 | 2015-10-30 | Power state-based train monitoring device and monitoring method |
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| CN107113548A CN107113548A (en) | 2017-08-29 |
| CN107113548B true CN107113548B (en) | 2021-02-02 |
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| KR100877587B1 (en) | 2007-07-07 | 2009-01-07 | 인터콘시스템스 주식회사 | Control system for safety operation of train |
| KR101174406B1 (en) * | 2010-04-14 | 2012-08-16 | 전자부품연구원 | A Low Power MAC Architecture for Wireless Sensor Network with Wireless Power Transfer |
| KR101288608B1 (en) * | 2011-09-08 | 2013-07-22 | 한국철도기술연구원 | Multi-Function Inspection Device Of Train and Railroad Using Power Generators Including A Piezoelectric |
| KR101396836B1 (en) * | 2011-12-26 | 2014-06-19 | 전자부품연구원 | Method for controlling contactless energy supply to wireless sensor network and system using the same |
| KR101488420B1 (en) * | 2013-04-30 | 2015-02-03 | 한국철도기술연구원 | System and method for monitoring a railroad car using wireless and self-generation sensor |
| KR102044002B1 (en) * | 2013-05-09 | 2019-12-02 | 한국전자통신연구원 | Dedicated channel establishment method for high speed data transmission in railway wireless sensor network |
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