JP2007129519A - Sensor network device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently know environmental change when it takes a long time to measure the environmental change. <P>SOLUTION: A first system comprises four measuring nodes 115a to 115d. The first node 115a is laid on a wall top surface, the second node 115b on a ceiling, the third node 115c on a desk, and the final fourth node 115d on a floor. An instruction from a base station is transmitted to respective nodes via the first node 115a, second node 115b, and third node 115c, and information while gathered in order from the fourth node 115d to the base station is transferred. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention integrates information from environmental data obtained using sensors via a wireless network, a single-hop wireless network that directly feeds back from the device, or an information source that provides a plurality of environmental data. It belongs to the field of measuring elements for measuring environmental data.

  Indoor environmental data is used for people to spend comfortably in the room. Examples of environmental data include temperature, humidity, sunshine level, and wind speed. The environmental data is mainly used as an index for applying feedback to prevent the change and return to the original state when the value changes. The environmental data can be classified into those in which the value can be measured instantaneously when the value is measured and those in which an accurate value or a stable value cannot be obtained without waiting for a certain amount of time. In the former example, sunshine hits it. Sunlight is to determine whether or not the sun's light is inserted into the room, so that a current change occurs when light enters a sunlight sensor such as a photodiode. The value can be measured instantaneously, and if the sunshine condition does not change, the value does not change greatly. Therefore, feedback with the measured value, eg curtains, can be closed. In the latter example, this is the temperature sensor. In general, a temperature sensor takes time to reach an equilibrium state with respect to a temperature change. Particularly, a highly accurate temperature sensor, for example, a temperature having an accuracy of one decimal place or more, takes about 10 to 15 minutes. There are many things. An air conditioner is a device that gives feedback on temperature, but because air is used to control temperature, it takes time until cold air or hot air reaches the position of the sensor, and air with different temperatures is less likely to mix. Due to its nature, it takes more time for air at different temperatures to mix and reach equilibrium, resulting in a time difference in the feedback itself.

  A temperature sensor for a general air conditioner is fixed to a wall or the like, and the temperature is measured in one place, which causes a temperature difference in the room. In recent years, a number of temperature sensors have been placed in a room, and the values of each sensor are used for overall control to reduce the temperature difference depending on the location in the room. In locations that are in contact with outside air with a difference, the temperature changes greatly depending on the opening and closing of the door and the entry and exit of humans. In this case, it is difficult to quickly return the temperature of the place where the temperature has changed to a value before the change occurs in terms of the performance of a general temperature sensor or air conditioner. Of particular concern is the reaction rate of the temperature sensor. In general, when feedback regarding temperature is applied, the response characteristic of the temperature sensor is assumed and feedback is performed up to a set temperature.

  And a wireless sensor that controls the temperature in the room using the value received by the base station by sending temperature information using a wireless network to the base station so that the temperature can be controlled at any place in the room. In the network, the increase in the measurement frequency causes the battery to be consumed when the nodes constituting the wireless network are driven by the battery, resulting in shortening the operating life of the wireless network itself.

  In the hierarchical wireless self-organization network, the central base station is removed so as to avoid a single point of failure. Instead, it is controlled in a distributed manner by the backbone nodes, and information about the entire network can be accessed at any time from any backbone node.

For example, if each node or link fails in the sensor / actuator node, it is executed using the alternative path information of the cluster head obtained and stored locally in the individual sensor / actuator node. Further, the lost node acquires valid route information from a certain adjacent node by using the “SOS” message. (See Patent Document 1)
JP 2005-515695 A (paragraphs 0065 to 0069, FIG. 2)

  In the conventional technology, it takes time until the sensor reacts or shows a stable numerical value, and feedback is given to the change, so that the original state or newly set state can be obtained within a short time. It was difficult to do.

  In particular, in a system that collects environmental data via a sensor node using a multi-hop type radio and manages it centrally, the measurement frequency is compared with the method of acquiring the value directly from the sensor by conventional wired connection Then, when the set value and the actual value are greatly different from each other, such a long state may cause discomfort to the person in the room. On the other hand, by using a multi-hop type wireless sensor network, it became possible to individually measure the state of the partial parts by a plurality of sensor nodes. As a result, detailed environmental information can be obtained, but the environmental changes with time in each part are not the same. For example, taking temperature information of one room as an example, in the part close to the door, outside air flows into the room due to opening and closing of the door, so there are many cases where a large temperature change is instantaneously shown. Similarly, the window side is often affected by the weather condition, and on a clear day, the window side can be watched for a rapid temperature rise. On the other hand, since the center of the room is far from the factor causing the temperature change, the temperature change generally remains in a low range. Therefore, it is necessary to change the performance of the sensor in accordance with the degree of environmental change of each part. In addition, when feedback is excessively applied, there is a risk of causing a so-called oscillation phenomenon in which feedback is applied more than necessary and exceeds a set value, and reverse feedback is applied thereto. It is a method of applying appropriate feedback in a timely manner to changes. Therefore, the problem to be solved by the present invention is that when an environmental change occurs, the sensor efficiently changes the environmental change that takes a long time to show a correct value when the environmental change occurs. In the measurement node that constitutes the same sensor network as the capturing method, the sensor performance selection method according to the degree of environmental change and when the measurement node that constitutes the multi-hop sensor network loses its function This is a method for estimating environmental data at the position of a measurement node that has lost its function.

The present invention provides a sensor network device that transmits a plurality of sensors of the same type having different performances in a sensor network that transmits sensor information using radio, and the node measures one physical value. is there.
The present invention is a sensor network device that applies feedback using information obtained from the sensor.
The present invention is a sensor network device in which a combination of the sensors is different in accordance with a condition of a place where the node installs the node.
The present invention provides a sensor network that constitutes a multi-hop wireless network and estimates the sensor value of another node adjacent to the node from the value of the adjacent sensor node when the node loses the function of the sensor Device.

  As a wireless network serving as a basis for solving the above-described problems, a multi-hop wireless network that collects environmental information via a plurality of measurement nodes is used, and temperature information is used as an example of the environmental information.

  The multi-hop wireless network uses weak wireless of 315 MHz, and the number of measurement nodes constituting the network, that is, 40 wireless devices that perform high-frequency modulation and flow through the network by measuring temperature information is measured. . The room used for the measurement is a room with a door on one side and a window facing the outside on the other side of the door. The measurement node 140 has one base station, 13 130 on the ceiling, and 13 120 Thirteen pieces 110 were placed on the wall or at a position close to the floor. A measurement node serving as a base station, that is, a base station node 140, is connected to a computer 150 via a wired interface. The computer 150 is equipped with software for controlling the wireless network and software for analyzing collected data, and the temperature information measured by the measurement nodes constituting the wireless network can be displayed on the computer 150. Using this information, the room temperature environment shown in FIG. 1 can be analyzed.

  Three systems of multi-hop wireless networks are formed from the measurement nodes 110, 120, and 130 serving as base stations. FIG. 1 shows the environment used to implement the present invention and the state of the wireless network. However, the number of measurement nodes is shown only for each system.

  By using a multi-hop wireless sensor network, environmental indicators that have been managed or fed back by a single or a limited number of fixed sensors can be measured in many measurement locations. It was. Moreover, even a sensor that takes time to display information until it reaches a steady state, such as temperature information, is difficult to use with a single sensor by using multiple temperature sensors with different performances. It is now possible to grasp environmental indicators quickly. At the same time, changes in environmental indicators over time vary from place to place, so by selecting and arranging sensors with characteristics that match the changes in the environment indicators at that place, it is possible to grasp the indicators at a speed that corresponds to the changes in the environment indicators. It became.

  The present invention relates to a method for quickly grasping a temperature change using two temperature sensors having different reaction rates as Example 1, and in Example 2, two different places in the room, the vicinity of the door and the center of the room. As a method for selecting a sensor, the third embodiment will explain a data complementing method when a measurement node that loses its function among a plurality of measurement nodes is generated.

  A wireless device incorporated in a self-supporting wireless sensor network is generally driven by a battery or battery. This is because if the power source is taken from an AC power source, the installation location of the wireless device is fixed, and it is difficult to place the sensor at an appropriate position when the partition is changed by the environment, for example, redesign. In recent years, in office buildings, it has become common to design each floor as one large space without partitioning and partitioning as needed. Changing the partition will change the effectiveness of the air conditioning. Therefore, it is necessary to move or set according to the environment where the position of the sensor is partitioned. This is why battery driving is common in wireless devices built into wireless sensor networks.

  On the other hand, as for the sensor, when it is fixed to the wall or the like and there is no worry about the power supply, a large amount of current generally called a resistance type or thermistor type is passed, but a highly accurate one is often used. However, it is unsuitable as a sensor for a wireless sensor network with a limited power supply. In recent years, sensors with a fast reaction speed have been introduced while reducing current consumption. In general, a sensor called a sea moss (CMOS) type consumes many microamperes or less during operation.

  As far as temperature and humidity sensors are concerned, there are two definitions of stabilization time. First, when the temperature changes, for example, when the room temperature rises by 5 degrees, the stabilization time that defines the time to follow the new temperature from before the change, then until the accurate value is shown after the power is turned on There is a stabilization time that defines the time required for.

The former is defined as the following stable time, and the latter is defined as the required stable time. Temperature / humidity sensors with good measurement accuracy often have a long follow-up stability time, and many follow-up stabilization times after a temperature change take 10-15 minutes, but the temperature measurement accuracy is about ± 0.1 degrees is there. On the other hand, a temperature / humidity sensor that responds quickly to temperature changes reacts in seconds, but it is not uncommon for temperature measurement accuracy to exceed ± 2 degrees. However, the required stabilization time is often several seconds, for example, 4 seconds or less.

  In wireless sensor networks, it is necessary to reduce the energization time of the sensor as much as possible and to require a quick response, which is a contradictory condition. This embodiment is intended to solve this problem.

  In this embodiment, the wireless sensor network performs temperature / humidity measurement by using two temperature / humidity sensors having a short tracking stability time but having a low measurement accuracy and two temperature / humidity sensors having a long tracking stability time but a high measurement accuracy. . The former temperature / humidity sensor is defined as a high-speed sensor, and the latter temperature / humidity sensor is defined as a precision sensor. The high-speed sensor used in this example has a specification that the tracking stability time is 15 seconds, the temperature measurement accuracy is ± 1.5 degrees, and the required stability time is 4 seconds or less. The precision sensor has a tracking stability time of 15 minutes, A CMOS sensor having a temperature measurement accuracy of ± 0.1 degrees and a required stabilization time of 4 seconds or less was used.

  FIG. 2 is a diagram of one of the three multi-hop wireless sensor networks shown in FIG. 1 extracted from the horizontal direction. This line is designated as the first line. The first system includes four measurement nodes 115a to 115d. The first node 115a is laid at various locations on the wall upper surface, the second node 115b is laid on the ceiling, the third node 115c is laid on the desk, and the last fourth node 115d is laid on the floor. When a command such as “acquire temperature information” is sent, the command is transmitted from the base station to each node via the first node 115a, the second node 115b, and the third node 115c, and the base station sequentially starts from the fourth node 115d. FIG. 3 shows what information the nodes 115a to 115d carry around in the storage device when the information is transferred to the station while collecting the information.

  The case information shown in FIG. 3 is temperature information if the command is “acquire temperature”. A command issued from the base station 140 is transmitted from the first node 115a to the second node 115b, from the second node 115b to the third node 115c, and from the third node 115c to the fourth node 115d. Then, the fourth node 115d sends information 4 held by the fourth node 115d to the third node 115c. The third node 115c receives the information 4 of the fourth node 115d, and has the information 3 of the third node 115c itself and the information 4 of the fourth node 115d. The third node 115c sends information 3 and information 4 to the second node 115b. The second node 115b receives information 3 and information 4. The second node 115b has information 3 and information 4 received from the third node 115c and information 2 which is information of the second node 115b itself. The second node 115b sends information 2 to information 4 to the first node 115a. The first node 115a receives information 2 to information 4 sent from the second node 115b. The first node 115a has information 2 to information 4 received from the second node 115b and information 1 which is information of the first node 115a itself. Then, the first node 115 a sends information 1 to information 4 to the base station 140. In this way, the base station 140 obtains information 4 from information 1 that is information of each node included in the first node 115a to the fourth node 115d.

  A high-speed sensor and a precision sensor have different responses to temperature changes when the temperature changes. An example of the reaction is shown in FIG. 4 and FIG. 6 ”. In FIG. 4 and FIG. 6, the high-speed sensor responds to a new temperature and takes a short time until it shows a value close to the new temperature. For example, the display temperature does not stabilize even after 30 minutes or more, and shows a value that fluctuates in the temperature measurement accuracy range, whereas the precision type sensor has a temperature measurement accuracy range of ± 0.1 degrees after the tracking stabilization time has elapsed. Stay in the narrow range said.

  Next, temperature measurement performed by mounting two sensors having different reaction rates will be described. FIG. 5 is a schematic diagram showing a configuration of a measurement wireless node equipped with a temperature sensor having a different performance, a high-speed temperature sensor, and a precision temperature sensor. In FIG. 5, the first sensor 540 is a high-speed temperature sensor, and the second temperature sensor 550 is a precision temperature sensor. The measurement node 500 includes a central processing unit 530 that reads the first and second sensors 540 and 550 and their values, stores them in the storage device 560, and controls wireless communication, and stores sensor values and other data. A storage device 560, a wireless module 520 and an aerial 510 that constitute a high-frequency circuit, and a power source 570 that supplies electric power to these devices, for example, a battery.

  Consider the second node 115b in the multi-hop wireless network shown in FIG. It can be assumed that the room in which the wireless network shown in FIG. 2 is laid is air-conditioned and the doors 170 and windows 160 are not opened and closed, so that the temperature and humidity are maintained almost constant. Assume that the room temperature is lower than the outdoor temperature. Therefore, when there is a person who opens the door 170 and enters the room, it is imagined that the outside air flows near the door 170 and the room temperature rapidly increases. Here, the reaction of the first node 115a in FIG. 2 will be described. The first node 115a is a measurement wireless node 500 having two types of temperature / hygrometers having different reaction rates shown in FIG.

  Regarding the first node 115a, the reaction of the temperature sensor when there is a person who opens the door 170 and enters the room will be described. The first node 115a measured twice immediately after the door was opened, that is, immediately after the temperature change occurred, and after a sufficient time had elapsed since the temperature change occurred. The former is measurement point 1 and the latter is measurement point 2. First, at the measurement point 1, the high-speed sensor reacts quickly, which is significantly different from the value indicated by the precision sensor, and the values do not overlap even if sensor errors are taken into account. Accordingly, the temperature at the measurement point 1 is determined to be a more accurate value indicated by the high speed sensor, and the value indicated by the first node 115a is a value indicated by the high speed sensor. On the other hand, at the temperature measured at measurement point 2 near the equilibrium point of the sensor display, even if the value of the precision sensor takes into account the measurement error, it is included in the value taking into account the measurement error of the high-speed sensor. It has been done. In this case, the value of the precision sensor with less measurement error is a value indicated as the sensor value of the first node 115a. In this way, when there is a sudden environmental change, a value closer to the actual temperature can be adopted among the values indicated by the two sensors. In this case, the timing at which the value indicated by the high-speed sensor switches from the value indicated by the high-speed sensor after the sudden temperature change occurs includes the value of the high-precision sensor that also takes into account the measurement error. Sometimes.

  Next, a method for selecting the temperature / humidity sensor will be described. In FIG. 2, there are four measurement nodes. The first node 115a is on the wall surface near the door 170, the second node 115b is on the ceiling near the window 160, the third node 115c is on the desk in the center of the room, and the fourth node 115d is on the floor near the window 160. It is laid on the top. As described in the first embodiment, since the outside air flows into the door 170 when the door 170 is opened and closed, a rapid temperature / humidity change is likely to occur. Similarly, since the inflow of outside air can be considered by opening and closing the window 160, there is a possibility of a rapid temperature change. In addition, since sunlight is irradiated near the window, even if the window 160 is closed, the vicinity of the window 160 rises in temperature due to heat generated by sunlight. Especially in summer, the rise in temperature is remarkable. On the other hand, if it is assumed that the room is air-conditioned at the desk position in the center of the room, the temperature change is not significant by the distance from the factor that causes a rapid temperature change such as the window 160 and the door 170. Therefore, air conditioning can be managed with higher accuracy by selecting a greenhouse temperature sensor based on the assumed amount of change in temperature and humidity.

  In this example, the measurement nodes equipped with two sensors shown in FIG. 5 were compared with the greenhouse sensor to be installed in the first node 115a and the third node 115c shown in FIG. There are three types of temperature and humidity sensors, sensor 1 for convenience, temperature response rate is low and measurement accuracy is high, sensor 2, temperature response rate and measurement accuracy are medium, sensor 3, temperature response rate is high and measurement accuracy is It was low.

  First, in the first node 115a, as described in the first embodiment, since a rapid temperature change is expected, the performance of the two temperature / humidity sensors to be mounted is more appropriate. Sensor 1 and Sensor 3 were selected. On the other hand, the third node 115c is a place where there is little environmental change, and at the same time, there is a possibility that there is a person sitting on the chair and working toward the desk, so the display temperature due to the measurement error of the temperature and humidity sensor Is a problem. That is, when feedback is applied to the air conditioning due to a measurement error, it is uncomfortable to constantly hit air of different temperatures when the air conditioner is turned on and off, resulting in a decrease in work efficiency. Therefore, the sensor 1 and the sensor 2 are selected for the third node 115c.

  The same is true for a measurement node with a single sensor. If the number of sensors mounted on the first node 115a and the third node 115c is one, the sensor 3 should be selected for the first node 115a and the sensor 1 or sensor 2 should be selected for the second node 115b. is there.

  As shown in this example, it is possible to measure more finely grained by selecting a temperature / humidity sensor with different performance in a place where the environmental change is remarkable and a place where it is not so in the same room. .

  A feature of the multi-hop wireless communication network is that one wireless device in the network, in the previous two embodiments, completes communication by continuing communication even if the measurement node does not function. It is characterized by being able to. However, the fact that a specific measurement node is not functioning means that even if the communication network is not destroyed, data to be provided by the measurement node that is not functioning is not provided. The data of individual measurement nodes not provided in the past is generally inherited from the last measured value or replaced with a set value. However, in the case of temperature and humidity, there is a change over time. It is an expected environment variable, and the method of deferring the value just because the measurement value is not provided or inheriting the set temperature cannot reflect the change. In addition, since it is assumed that it takes a certain amount of time to repair the measurement node that has stopped functioning and to return to the network, it is assumed that the time during which the change is not reflected continues to some extent.

  In this example, when a measurement node that does not function stops functioning, the measurement node that does not function is inferred from the value of the measurement node existing in the vicinity, and the value that the estimated value does not function is estimated. The method used as the value of the node is shown.

Two methods are conceivable as a method of estimating the value of the measurement node that does not function. The first method is a method in which the values of measurement nodes arranged before and after measurement nodes that do not function in the same environment or function in the same series of multi-hop wireless sensor networks are averaged. In FIG. 2, the number of measurement nodes is as small as four, and there are no two measurement nodes arranged under the same condition or near conditions. A multi-hop network has a disadvantage in that the communication time is long in order to continue the one-to-one communication. In a network that expects fast feedback, it is possible to collect a wide range of measurement data in a short time by reducing the number of measurement nodes belonging to one branch and increasing the number of branches. Therefore, although the second method is between different branches, in FIG. 1, three multi-hop wireless sensor networks measure the temperature and humidity information of each part of one room. There are roughly three types: mounting on the ceiling, wall mounting and floor mounting. Among them, for example, there is one measurement node laid on the ceiling for each system, and when one of these measurement nodes loses its function, it loses its function among the other two measurement nodes laid on the ceiling. The value closer to the condition of the measured node can be the value of the measured node that has lost its function.

  The function will be described in detail with reference to FIG. FIG. 7 shows a multi-hop wireless sensor network of system 0 composed of node 01, node 02, node 03 and node 04, and a multi-hop wireless sensor of system 1 composed of node 11, node 12 and node 13. A network exists. Both the system 0 and the system 1 adopt a method of collecting information in the same base station 140.

  FIG. 7 shows a communication path when all measurement nodes are functioning normally. FIG. 8 shows a communication path when one communication node, for example, the node 02 loses its function. If the node 02 is functioning normally, the node 01 should communicate with the node 02, or the node 03 should communicate with the node 02. However, in FIG. You are communicating directly without going through. Therefore, although communication is ensured in the system 0, the temperature / humidity data that should be originally supplied by the node 02 is not supplied. In this case, if the condition is close to that of the node 02, the node 12 of the system 1 corresponds to it. In this embodiment, after all the information is collected in the base station 140, the value of the node 12 is substituted for the value of the node 02 and supplied to the data processing computer shown in FIG.

  The multi-hop wireless sensor network system of the present invention measures the difference in temperature and humidity depending on the office and the location inside the building, and appropriately measures the temperature and humidity values that change over time. By applying feedback to the appropriate value and wind direction, it can be used as an environmental information measurement system to save wasteful power and provide an optimal environment for people who act in the place.

Schematic diagram of a multi-hop wireless sensor network Example of a single multi-hop wireless sensor network viewed from the horizontal direction Data retention status for multi-hop wireless networks Example of temperature response curve of two temperature sensors with different performance Configuration diagram of a wireless measurement node equipped with two temperature sensors with different performance Example of temperature response curve of two temperature sensors with different performance Multi-hop wireless sensor network and proximity measurement node Multi-hop communication system diagram when node 02 stops functioning

Explanation of symbols

115 Node 500 Measurement node 510 Antenna 520 Wireless module 530 Central processing unit 540 First sensor 550 Second sensor 560 Storage device 570 Power supply

Claims (4)

2. Description of the Related Art A sensor network device that transmits a plurality of sensors of the same type having different performances in a sensor network that transmits sensor information using radio, and the node measures one physical value. The sensor network device according to claim 1, wherein feedback is performed using information obtained from the sensor. The sensor network device according to claim 1, wherein the node is combined in a different manner according to a condition of a place where the node is installed. The sensor according to claim 1, wherein a sensor value in another node adjacent to the node is inferred from the value of the adjacent sensor node when the multi-hop wireless network is configured and the node loses the function of the sensor. Network device.

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