JP2011142439A - Data collection system and data collection server thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data collection system which can do collection as data collection server repeats sensor data from a lot of sensor nodes in concentration without causing an excessive load in a network and the data collection server, and also to provide the data collection server thereof. <P>SOLUTION: The average value of sensor data D1 transmitted from one sensor node 1a and sensor data D2 received from another sensor node 1b is obtained as statistics Ds, and future transitions are predicted, for example, by extrapolation (extrapolation), regression analysis, or a least squares method on the basis of transition results up to the present time t0 of the statistics Ds. Then, a time tx when a deviation &Delta;Ds between statistics Ds(t0) at the present time and a predicted value Ds(tx) exceeds a predetermined threshold Ds_ref is calculated, and the time tx is determined as communication timing tp of sensor data D. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a data collection system that repeatedly collects sensor data from a plurality of sensor nodes including sensors that detect physical quantities, and a data collection server thereof.

  Various types of sensors such as step sensors, positioning sensors, temperature sensors, and acceleration sensors are provided in wireless portable terminals such as mobile phones, PDAs, and pocket computers to function as sensor nodes, and sensor data measured by each sensor is sent via a network. A technique for performing statistical processing by transmitting to a data collection server is known.

  In Patent Document 1, a host server and a user portable terminal are connected to the Internet, and the user's heart rate data, blood pressure data, and body temperature measured by the measuring device and the electrocardiograph through the user portable terminal possessed by the user. Data, step count data, and electrocardiogram data are transmitted to a host server (data collection server), and the host server discloses a technique for storing and analyzing the received data.

  In Patent Document 2, the competition management server 1 (data collection server) receives and registers the participation of the player H from the terminal device 2 of the player H via the communication line, and is unique to the player H. When the athlete code is issued, the athlete code is recorded through the terminal device 2 of the athlete H, and time information on the competition time acquired using the IC chip attached to the athlete H is given to the athlete H. Is received from the terminal device 2 via a communication line, and a technique for determining the competition ranking of each athlete H based on this time information is disclosed.

  However, in the above prior art, transmission of sensor data from a sensor node (user portable terminal, terminal device) possessed by the user to the data collection server is repeated at a predetermined constant cycle. Therefore, for example, a citizen marathon where a large number of runners participate, and a virtual marathon where a large number of geographically dispersed joggers compete virtually to collect sensor data from many users intensively and repeatedly. However, network congestion and processing load on the data collection server may temporarily become excessive.

  In response to such a technical problem, the inventors of the present invention monitor changes in sensor data at each sensor node, and refrain from sending to the data collection server unless the sensor data deviates from the change prediction range. When data is accumulated and the sensor data deviates from the change prediction range, the accumulated data is sent to the data collection server at a time, thereby preventing an increase in communication traffic and reducing the processing load on the data collection server. We have invented a system that can be reduced and applied for a patent (Patent Document 3).

JP 2003-52648 A JP 2008-299535 A Japanese Patent Application No. 2009-46423

  When the data collection server wants to obtain, for example, an average value as a statistic of sensor data collected from each sensor node, sensor data Da detected by the two sensor nodes A and B as shown in FIG. , Db are in antiphase, the average value indicates a constant value, so the data collection server does not need to frequently collect sensor data Da, Db from each sensor node A, B.

  However, in Patent Document 3, each sensor node determines the necessity of data transmission based on a change in its own sensor data D. Therefore, when the sensor data D periodically changes greatly as shown in FIG. , B frequently sends data to the data collection server.

  For example, in each sensor node A, B, if the rule “transmit when the change amount of sensor data D is“ 1 ”or more” is set, each sensor node A at time t1, t2, t3, t4. , B will send data.

  The object of the present invention is to solve the above-mentioned problems of the prior art and to enable the data collection server to collect sensor data from a large number of sensor nodes intensively and repeatedly without causing an excessive load on the network or data collection server. It is to provide a collection system and a data collection server thereof.

  In order to achieve the above object, the present invention provides a data collection system in which a plurality of sensor nodes each having a sensor for detecting a physical quantity transmit sensor data to a data collection server, and the following means in the data collection server There is a feature in the point that I took.

  (1) In the data collection system of the present invention, a sensor node detects a physical quantity and outputs sensor data, means for acquiring communication timing for transmitting sensor data from the data collection server, and sensor data Means for transmitting to the data collection server at the communication timing. The data collection server also includes means for receiving sensor data from each sensor node, means for statistically processing the sensor data to calculate statistics, and communication timing for collecting sensor data based on the statistics. Means for determining, and means for notifying the sensor timing of the communication timing.

  (2) The data collection server of the present invention collects sensor data on the basis of means for receiving sensor data from each sensor node, means for statistically processing sensor data to calculate statistics, and statistics Means for determining the communication timing to be performed, and means for notifying the sensor node of the communication timing.

  (3) In the data collection server of the present invention, the means for determining the communication timing includes means for predicting a statistic transition, and means for calculating a communication timing at which the predicted value of the statistic satisfies a predetermined condition. It has.

  (4) In the data collection server of the present invention, the means for calculating the communication timing calculates a time when the difference between the current value of the statistic and the predicted value exceeds a predetermined threshold.

  According to the present invention, the following effects are achieved.

  (1) In the data collection server, regardless of changes in sensor data detected at each sensor node, the communication timing for collecting sensor data from each sensor node is based on the statistics calculated based on each sensor data. Therefore, even if the sensor data changes, communication for collecting the sensor data from each sensor node is not performed unless the statistics change. Therefore, it is possible to reduce traffic related to sensor data communication and access to the data collection server.

  (2) In the data collection server, until the statistic calculated based on the sensor data collected from each sensor node is predicted to change beyond a predetermined threshold, it is necessary to collect sensor data from each sensor node. Since communication is not performed, access to the communication traffic and the data collection server can be reduced without greatly reducing the accuracy of the statistics.

It is the block diagram which showed the structure of the information collection system which concerns on one Embodiment of this invention. It is the block diagram which showed the structure of the principal part of a sensor node. It is the block diagram which showed the structure of the principal part of a data collection server. It is the figure which expressed typically an example of the determination method of communication timing. It is the flowchart which showed operation | movement of a sensor node. It is the flowchart which showed operation | movement of the data collection server. It is a sequence flow of data communication performed between each sensor node and a data collection server. It is a figure for demonstrating an error (error). It is the figure which showed transition of the sensor data D detected by five sensor nodes. It is the figure which showed transition of statistics Ds_real of the sensor data D shown in FIG. The figure which showed the difference | error between the statistics Ds_real calculated from each sensor data D of FIG. 9, and the statistics Ds_cal estimated by the least square method by acquiring each sensor data D with a predetermined period for every acquisition period It is. It is the figure which showed the error in the case of acquiring sensor data D at the timing when the difference of statistics Ds_real and Ds_cal exceeds a predetermined threshold. It is the figure which showed the relationship between the frequency | count of transmission of the sensor data D, and the error error regarding the conventional method and the data collection system of this invention. It is a figure for demonstrating the subject of a prior art.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a main part of a data collection system according to an embodiment of the present invention, and various sensors such as a step sensor, a temperature sensor, a humidity sensor, an acceleration sensor, an illuminance sensor, and a positioning system. A plurality of wireless sensor nodes 1 equipped with a wireless base station 2 accommodating the sensor node 1 located in its own wireless area, each wireless base station 2 and each sensor node 1 via the Internet A data collection server 3 that collects sensor detection results (sensor data) and statistically processes them is the main configuration.

  FIG. 2 is a block diagram showing the configuration of the main part of the sensor node 1, and various sensors such as a step sensor P1, a temperature sensor P2, a humidity sensor P2, an acceleration sensor P3, an illuminance sensor P4, or a positioning system P5, Outputs the physical quantity to be detected. The sensor data acquisition unit 101 converts the physical quantity detected by each sensor Px into sensor data D and outputs it. The sensor data storage unit 102 stores the sensor data D in time series.

  The communication timing acquisition unit 103 acquires a message notified from the data collection server 3 regarding the communication timing ts for transmitting the sensor data D to the data collection server 3. The sensor data transmission unit 104 waits for the notified communication timing ts, and transmits untransmitted sensor data D stored in the sensor data storage unit 102 to the data collection server 3 at a time.

  FIG. 3 is a block diagram showing the configuration of the main part of the data collection server 3. The sensor data receiving unit 301 receives sensor data D transmitted from each sensor node 1. The sensor data storage unit 302 stores the sensor data D in time series. The statistic calculation unit 303 statistically processes the sensor data D to calculate the statistic Ds.

  In the communication timing determination unit 304, the prediction unit 304a predicts the transition by extrapolation (extrapolation), regression analysis, or least squares method based on the history of the statistic Ds. The calculation unit 304b calculates a future time tp when the predicted value of the statistic Ds satisfies a predetermined data collection condition, and determines this as the communication timing ts for collecting the sensor data D from the sensor node 1. The communication timing notification unit 305 notifies the sensor node 1 of the communication timing ts.

  FIG. 4 is a diagram schematically representing an example of a method for determining the communication timing tp by the communication timing determination unit 304.

  In the present embodiment, the average value of the sensor data D1 transmitted from one sensor node 1a and the sensor data D2 received from the other sensor node 1b is obtained as the statistic Ds, and the current time of the statistic Ds Based on the transition results up to t0, future transitions are predicted by, for example, extrapolation, regression analysis, or least squares method. Then, a time tx at which the deviation ΔDs between the statistic Ds (t0) and the predicted value Ds (tx) at the current time t0 exceeds a predetermined threshold value Ds_ref is determined as the next communication timing tp.

  Next, the operation of the embodiment of the present invention will be described in detail with reference to a flowchart. FIG. 5 is a flowchart showing the operation of the sensor node 1, and FIG. 6 is a flowchart showing the operation of the data collection server 3. FIG. 7 is a sequence flow showing a procedure of data communication performed between each sensor node 1 and the data collection server 3.

  In FIG. 5, in the sensor node 1, the first sensor data D is transmitted from the sensor data transmission unit 104 to the data collection server 3 in step S <b> 1. In the present embodiment, the sensor data D is described in a TCP packet or a UDP packet and transmitted. In step S2, it is determined whether or not the next communication timing tp is notified from the data collection server 3. If not notified, the process proceeds to step S5, and sensor data D sampled at a predetermined sampling period in each sensor Px is temporarily stored in the sensor data storage unit 102 in time series, and this is repeated.

  In FIG. 6, when the sensor data D transmitted from each sensor node 1 is received by the sensor data receiving unit 301 in step S21, the data collection server 3 proceeds to step S22. In step S22, each sensor data D is stored in the sensor data storage unit 302 in time series. In step S <b> 23, the statistic Ds is calculated by the statistic calculation unit 303 based on the sensor data D stored in the sensor data storage unit 302. In the present embodiment, as described with reference to FIG. 4, the average value of each sensor data D is calculated and used as the statistic Ds.

  In step S24, based on the history of the statistic Ds, the transition is predicted by the prediction unit 304a by extrapolation, regression analysis, or least square method. In step S25, the calculation unit 304b predicts a future time tx when the statistic Ds satisfies a predetermined data collection condition. In the present embodiment, a future time tx at which the difference between the statistic Ds (t0) and the predicted value Ds (tx) at the current time t0 exceeds a predetermined threshold Ds_ref is predicted.

  In step S26, a period (tx−t0) from the current time t0 to the future time tx is compared with a predetermined upper limit value tmax. If (tx−t0) ≧ tmax, the process proceeds to step S27, and the future time tx is updated to the upper limit value tmax. In step S28, the future time tx is notified from the communication timing notification unit 305 to each sensor node 1 as the next communication timing tp.

  The next communication timing tp may be generated and transmitted a new message packet, but is described and returned in the confirmation response packet for the sensor data D received from each sensor node 1 in the immediately preceding step S21. You may do it. That is, if the sensor data D is received as a TCP packet, the next communication timing tp is described in a TCP ACK packet and returned, and if received as a UDP packet, it is described in a UDP ACK packet and returned. May be. In this way, no new traffic is generated to notify the next communication timing tp.

  Returning to FIG. 5, in the sensor node 1, when the communication timing tp is received by the communication timing acquisition unit 103 in step S2, the process proceeds to step S3. In step S3, it is determined whether or not it is the communication timing tp. Until the communication timing tp, the process proceeds to step S6, and sampling and accumulation of sensor data D are continued.

  Thereafter, when the communication timing tp is reached, the process proceeds to step S4, where untransmitted sensor data D stored in the sensor data storage unit 102, that is, sensor data sampled between the previous communication timing and the current communication timing. D is read. This sensor data D is transmitted to the data collection server 3 in step S1.

  Next, the simulation result of the present invention will be described. The simulation conditions here are as follows.

(1) Number of sensor nodes: 5
(2) Simulation time (duration): 5000 seconds
(3) Prediction model for statistics Ds: least squares method

  In the least square method as the prediction model, the order is “2” and the number of history data to be used is “3”. The evaluation indexes are as follows.

(1) Number of communications: Total number of communications per sensor node
(2) Error: A difference between a statistic Ds_real obtained by knowing that all sensor data D is known and a statistic Ds_cal predicted by the least square method based on each sensor data D. The error error corresponds to the area of each triangular area surrounded by a solid line (Ds_real) and a dotted line (Ds_cal) in FIG. 8, and is given by the following equation (1).

  FIG. 9 is a diagram illustrating the transition of the sensor data D sampled by each sensor node 1, and FIG. 10 is a diagram illustrating the transition of the statistic Ds_real of all the sensor data D. Here, the statistic Ds_real is the average value of the sensor data D.

  11 communicates an error between the statistic Ds_real calculated from each sensor data D in FIG. 9 and the statistic Ds_cal predicted by the least square method by acquiring each sensor data D in FIG. 9 at a predetermined cycle. It is a figure shown for every cycle of timing, and it can be seen that the error decreases as the cycle of communication timing becomes shorter.

  On the other hand, FIG. 12 is a diagram showing an error when the sensor data D is acquired at the communication timing tp in which the difference between the statistics Ds_real and Ds_cal exceeds a predetermined threshold by applying the present invention. These are the figures which showed the relationship between the frequency | count of transmission of the sensor data D, and the error error regarding the conventional method and the data collection system of this invention. In either method, the error decreases as the number of transmissions increases, but it can be seen that the present invention can achieve the same error with a smaller number of communications compared to the conventional method.

DESCRIPTION OF SYMBOLS 1 ... Wireless sensor node, 2 ... Wireless base station, 3 ... Data collection server, 101 ... Sensor data acquisition part, 102 ... Sensor data storage part, 103 ... Communication timing acquisition part, 104 ... Sensor data transmission part, 301 ... Sensor Data receiving unit, 302 ... sensor data storage unit, 303 ... statistic calculation unit, 304 ... communication timing determination unit, 305 ... communication timing notification unit

Claims (5)

In a data collection system in which a plurality of sensor nodes having sensors for detecting physical quantities transmit sensor data to a data collection server,
The sensor node is
A sensor that detects physical quantities and outputs sensor data;
Means for acquiring communication timing for transmitting sensor data from the data collection server;
Means for transmitting sensor data to a data collection server at the communication timing,
The data collection server is
Means for receiving sensor data from each sensor node;
Means for statistically processing sensor data to calculate statistics;
Means for determining a communication timing for collecting sensor data based on the statistics;
Means for notifying the sensor node of the communication timing. In a data collection server that collects sensor data from multiple sensor nodes,
Means for receiving sensor data from each sensor node;
Means for statistically processing the sensor data to calculate statistics;
Means for determining a communication timing for collecting sensor data based on the statistics;
A data collection server comprising: means for notifying the sensor timing of the communication timing. The means for determining the communication timing is:
Means for predicting the transition of the statistics,
The data collection server according to claim 2, further comprising means for calculating a communication timing at which the predicted value of the statistic satisfies a predetermined condition.   4. The data collection server according to claim 3, wherein the means for calculating the communication timing calculates a time at which a difference between a current value and a predicted value of the statistic exceeds a predetermined threshold value.   5. The means for notifying the sensor timing of the communication node returns the communication timing by describing the communication timing in an acknowledgment packet for sensor data received from each sensor node. 6. Data collection server.

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