JP2010032320A - Position detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detection system of a moving body capable of detecting easily accurate location information of each moving body in a prescribed area. <P>SOLUTION: This system is equipped with: a moving node composed of a means for receiving a packet including transmission time information, and a means for transmitting a packet having the same content as the received packet after elapse of a fixed time after receiving the packet; the first fixed node comprising a means for transmitting the packet including the transmission time information, a means for receiving the packet transmitted from the moving node, and a means for determining a distance to the moving node based on the transmission time information included in the received packet, time information on reception of the packet, and information of elapse of the fixed time; a plurality of second fixed nodes composed of a means for monitoring the packet transmitted from the first fixed node, a means for monitoring the packet transmitted from the moving node, and a means for calculating the distance to the moving node based on a reception time difference between the two monitored packets; and a means for calculating the position of the moving node based on distance information between each of the first fixed node and the plurality of second fixed nodes, and the moving node. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a position detection system for a moving body.

  As a method for detecting the location of each moving body in a building, a position detection method using ultrasonic waves has been proposed. For example, unidirectional ultrasonic waves transmitted from a moving body are received by a fixed receiver provided for each predetermined area in the building, and the position of the moving body is calculated from the time difference of ultrasonic signals received at at least three locations. The method is used (for example, refer to Patent Document 1). Further, in order to identify the positions of a large number of moving bodies, there is a method in which each moving body sequentially transmits ultrasonic signals based on a division time set in advance in a reference period.

  However, in order to obtain the arrival time difference between the received ultrasonic waves using this method, it is necessary to match the time division timing within the reference period in both the mobile unit and the fixed receiver. In comparison, it is necessary to use together communication means (for example, radio waves, infrared communication, wired communication) whose propagation time is negligible, and there is a problem that the circuit scale becomes large.

  On the other hand, as a method for improving the measurement accuracy of the distance between the moving body and the fixed receiver, there is a phase matching method (see, for example, Patent Document 2). This method also matches the time in advance in both the moving body and the fixed receiver. There is a problem that the circuit scale becomes large.

  As a method that does not require time adjustment for position detection, a request signal for requesting transmission of a response signal is transmitted from the access terminal to the transmission / reception terminal, and the response signal from the transmission / reception terminal is received after the request signal is transmitted. There is known a method of measuring a time until a transmission and calculating a distance to a transmission / reception terminal based on the measured time (see, for example, Patent Document 3). In this method, the same operation is sequentially performed from a plurality of access terminals, and the position of the transmission / reception terminal is calculated from the obtained distance data.

However, in order to specify the two-dimensional position of the transmitting / receiving terminal by this method, it is necessary to sequentially perform the same operation from at least three access terminals, and there is a problem that it takes time to specify the position.
Japanese Patent Laid-Open No. 08-226810 JP 2006-242640 A JP 2006-145223 A

  The present invention has been made in view of such circumstances. The purpose of the present invention is to perform time synchronization between a plurality of transmitters / receivers in advance by performing bidirectional communication and simultaneously receiving a plurality of transmitters / receivers. An object of the present invention is to provide a position detection system for a moving body that can easily detect accurate location information of each moving body within a predetermined area.

  The present invention includes: (a) a communication unit that transmits and receives a radio signal; a packet reception unit that receives a packet including transmission time information by the communication unit; and a packet that has been received after a predetermined time has elapsed since the packet was received. A mobile node comprising a packet transmission means for transmitting a packet having the same content by the communication means, (b) a communication means for transmitting / receiving a radio signal, and a packet transmission means for transmitting a packet including transmission time information by the communication means A packet receiving means for receiving the packet transmitted by the mobile node by the communication means, the transmission time information included in the packet received by the packet receiving means, the time information for receiving the packet, and the constant Based on the elapsed time information, a propagation time with the mobile node is obtained, and based on the propagation time. A first fixed node comprising a distance calculating means for obtaining a distance to the mobile node; (c) a communication means for receiving a radio signal; and a packet transmitted by the first fixed node by the communication means. Fixed node packet receiving means for intercepting, mobile node packet receiving means for intercepting a packet transmitted by the mobile node by the communication means, reception time of the packet received by the fixed node packet receiving means, and the mobile node packet receiving means A plurality of second fixed nodes comprising distance calculation means for calculating a distance to the mobile node based on a time difference from the reception time of the packet received by the distance information on the first fixed node; (D) distance information between the first fixed node and the mobile node and each of the plurality of second fixed nodes. Characterized by comprising a position specifying means for calculating the location of the mobile node based on the distance information between the mobile node calculated and the plurality of second fixed node by.

  According to the position detection system of the present invention, there is an effect that the position of a moving body in a predetermined area such as a room can be accurately detected with a simple device configuration.

  Hereinafter, a position detection system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment. In this figure, reference numeral 1 denotes the position of the moving body in the area A where the position of the moving body (here, a human) is to be detected, and the temperature control of the air conditioner and the lighting control in the area A are performed. It is a manager to perform and is composed of a computer or the like. Reference numerals 2, 3, 4, and 5 are fixed nodes for performing wireless communication using ultrasonic waves, and are installed at predetermined positions in the area A (for example, positions at four corners). Reference numerals 6 and 7 are mobile nodes carried by the user who uses the area A, and are mobile nodes that establish information communication using ultrasonic waves with the fixed nodes 2 to 5 and perform information communication. Reference numeral 8 denotes a local area network (LAN) that performs information communication between the four fixed nodes 2 to 5 and the manager 1.

  Next, the configuration of the fixed node 2 and the mobile node 6 shown in FIG. 1 will be described with reference to FIG. The fixed node 2 includes a speaker S that transmits an ultrasonic communication packet to the mobile node 6 and a microphone M that receives the ultrasonic communication packet from the mobile node 6. The mobile node 6 includes a speaker S that transmits an ultrasonic communication packet to the fixed node 2 and a microphone M that receives the ultrasonic communication packet from the fixed node 2. Since the fixed nodes 3 to 5 illustrated in FIG. 1 have the same configuration as the fixed node 2, detailed description thereof is omitted. Moreover, since the mobile node 7 shown in FIG. 1 has the same configuration as the mobile node 6, detailed description thereof is omitted.

  Next, the operation of the position detection system shown in FIG. 1 will be described with reference to FIGS. First, the operation of the manager 1 shown in FIG. 1 will be described with reference to FIG. First, the manager 1 initializes (clears) a result table that stores the position detection result of the moving object (step S1). Subsequently, the manager 1 selects a mobile node ID (step S2), and determines whether or not all the mobile nodes have been processed (step S3). As a result of the determination, if the processing is completed for all the mobile nodes, the mobile node ID is initialized (step S4), and the process returns to step S1.

  On the other hand, if all the mobile nodes have not been processed, the manager 1 selects a fixed node ID (step S5). Then, the manager 1 transmits a position detection command to the transmission fixed node having the selected fixed node ID via the LAN 8, and also receives the intercept command to the interception fixed nodes (here, the fixed nodes 3 to 5). Is transmitted (step S6).

  Next, the manager 1 receives the position detection result (distance information) from the fixed node (step S7), and stores this position detection result information in the result table (step S8). Then, the manager 1 determines whether or not there is a response from all the fixed nodes (step S9). If there is no response from all the fixed nodes as a result of this determination, the process returns to step S7 and is repeated.

  Next, if there is a response from all the fixed nodes, the manager 1 determines whether or not there are three or more valid result information in the position detection result (distance information) information stored in the result table. (Step S10). As a result of this determination, if there is not three or more pieces of valid result information, the manager 1 executes mobile node position indefinite processing (step S11). On the other hand, if there are three or more pieces of valid result information, the manager 1 obtains the intersection of the geometric circles from the three pieces of distance information, and calculates the mobile node position based on the coordinate value of this intersection (step S12). . Then, the manager 1 returns to step S1 and repeats the process.

  Next, the transmission operation of the fixed node 2 shown in FIG. 1 will be described with reference to FIG. First, when the fixed node 2 receives a position detection command from the manager 1 via the LAN 8 (step S21), the fixed node 2 acquires a time (transmission time) from a timer provided in the fixed node 2, and this transmission time. Is generated (step S22). Then, the fixed node 2 starts a timer for measuring the elapse of a predetermined time (step S23), and transmits the generated position detection packet into the area A (step S24). Then, the fixed node 2 determines whether or not a response from the mobile node in the area A has been received (step S25). If no response is received as a result of this determination, the fixed node 2 determines whether or not the timer has expired (timeout) (step S26). If the result of this determination is that the timer has not expired, processing returns to step S25 and repeats until the timer expires. When the timer expires, the fixed node 2 transmits an invalid result to the manager 1 via the LAN 8 (step S27).

  On the other hand, when there is a response from the mobile node, the fixed node 2 acquires the time (current time) from the timer provided in the fixed node 2 (step S28). Then, the fixed node 2 calculates the propagation time by subtracting the transmission time from the current time and further subtracting the packet communication time (TN) (step S29).

  Next, the fixed node 2 calculates the sound velocity according to the temperature from the temperature information (the temperature detected in the mobile node and the ambient temperature around the mobile node) included in the response packet received from the mobile node. Then, the distance between the fixed node 2 and the mobile node that has transmitted the response packet is calculated by multiplying the propagation speed by the calculated sound speed and dividing the result by 2 (step S31). Then, the fixed node 2 transmits the calculated distance information between the fixed node 2 and the mobile node to the manager 1 via the LAN 8 (step S32).

  Next, with reference to FIG. 5, the intercepting operation of the fixed nodes 3 to 5 shown in FIG. 1 will be described. Here, the operation of the fixed node 3 will be described as an example. First, when the fixed node 3 receives an intercept command from the manager 1 via the LAN 8 (step S41), the fixed node 3 starts a timer for measuring a predetermined time (step S42). Subsequently, the fixed node 3 determines whether or not communication interception has been made (step S43). As a result of this determination, if communication interception is not possible, the fixed node 3 determines whether or not the timer has expired (step S44). If the timer is expired as a result of this determination, the fixed node 3 transmits an invalid result to the manager 1 via the LAN 8 (step S45).

  On the other hand, when communication interception was successful, the fixed node 3 determines whether the packet is from another fixed node (step S46). If the result of this determination is that the packet is from another fixed node, the fixed node 3 stores the time (t1) (step S47). If the packet is not from another fixed node, the fixed node 3 determines whether the packet is from a mobile node (step S48). If it is determined that the packet is not from the mobile node, the process proceeds to step S44. If the packet is from the mobile node, the fixed node 3 stores the time (t2) (step S49).

  Next, the fixed node 3 determines whether or not the packet has been intercepted from both the other fixed node and the mobile node (step S50). If the packet is not intercepted from both as a result of this determination, the process proceeds to step S43. On the other hand, when the packet can be intercepted from both the other fixed node and the mobile node, the fixed node 3 subtracts the time t1 from the stored time t2 and further subtracts the packet communication time (TN). Time td is calculated (step S51).

  Next, the fixed node 3 calculates the sound speed according to the temperature from the temperature information included in the response packet intercepted from the mobile node (step S52), and multiplies the time td by the calculated sound speed. A difference distance (L2 + L3-L1 shown in FIG. 1) between the distance from the fixed node 2 to the fixed node 3 via the mobile node that has transmitted the response packet and the straight line distance from the fixed node 2 to the fixed node 3 is calculated (step S53). ). Then, the fixed node 3 transmits the calculated difference distance information to the manager 1 via the LAN 8 (step S54).

  Next, the operation of the mobile node 6 shown in FIG. 1 will be described with reference to FIG. First, the mobile node 6 receives a position detection packet from the fixed node 2 (step S61). Then, the mobile node 6 checks the mobile node ID included in the received packet (step S62) and determines whether or not it matches the mobile node ID of itself (step S63). As a result of this determination, if the mobile node ID does not match its own mobile node ID, the mobile node 6 ends the process (step S64).

  On the other hand, when the mobile node ID included in the received packet matches its own mobile node ID, the mobile node 6 starts a timer for measuring a predetermined time (step S65), and a temperature sensor provided therein. The temperature information is acquired from this, and a response packet including the temperature information is generated (step S66). Then, the mobile node 6 waits until the timer (TN) ends (step S67), and transmits the generated packet to the fixed node 2 when the timer ends (step S68).

  As described above, the fixed nodes 2 to 5 that can transmit and receive an ultrasonic radio signal and the mobile node 6 that can transmit and receive the ultrasonic radio signal constitute a position detection system, and the mobile node ID (identification information) and A packet including the fixed node ID and the transmission time is transmitted from the fixed node 2 by ultrasonic waves subjected to digital modulation, and a mobile node (for example, the mobile node 7) matching the designated ID is received after a fixed time from the fixed node 2 A packet having the same content as the transmission packet from is returned to the fixed node 2. The fixed node 2 that has received the packet reply including the self ID returns the round-trip signal between the nodes from the three points of the transmission time included in the returned packet, the reply reception time, and the reply delay of a certain time on the mobile node side. The propagation time is calculated, and the distance is calculated from the propagation speed. In this method, since the transmission time included in the packet and the time when the reply is received are based on the internal clock of the fixed node 2 itself, it is not necessary to synchronize the internal clock of each node in advance.

  Furthermore, the ultrasonic signal transmitted from the fixed node 2 to the mobile node 7 can be intercepted also by the other fixed node 3, and the fixed node 3 can also intercept the ultrasonic signal transmitted from the mobile node 6 to the fixed node 2. From the difference distance obtained from the reception time difference between the two intercepted signals, the known physical distance (L1) between the fixed node 2 and the fixed node 3, and the distance (L2) between the fixed node 2 and the mobile node 7, the manager 1 Can determine the distance between the fixed node 3 and the mobile node 7. By intercepting the ultrasonic transmission from the fixed node 2 and the reply of the mobile node 7 in this way, the manager 1 obtains the distance (L3) between the other fixed nodes 3 to 5 and the mobile node 7. This eliminates the need for each fixed node to sequentially communicate with the mobile node, reducing the time required to locate the mobile node to 1/3 or less. Note that the distance calculation by interception may actually be performed by each of the fixed nodes instead of the manager 1. Interception may not be possible depending on the environmental conditions, and only one or two fixed nodes may be able to determine the distance from the mobile node 7. In such a case, the same method may be used by changing the fixed node that transmits the packet. The distance may be obtained with the above, and the position of the mobile node may be specified based on the distance obtained from three or more fixed nodes.

  As described above, the position detection system according to the present invention does not use an ultrasonic wave as a burst wave as in the prior art, but modulates and transmits information on the ultrasonic wave and detects it after receiving it. Information is extracted. Thus, if the time and node ID transmitted from the fixed node are stored, the distance between the fixed node and the mobile node can be calculated from the response time from the mobile node and the sound speed. If this is performed at three or more fixed nodes, it is possible to detect where the mobile node is in the detection area (for example, indoors). Based on the user position information detected by the position detection method, it is possible to perform air conditioning control and lighting lighting control for individual users, so energy saving can be achieved reliably.

  In the above description, as an example of using wireless communication by ultrasonic waves as a method for realizing wireless communication, the method for realizing wireless communication is not limited to ultrasonic waves. It may be used.

  Also, a program for realizing the functions of the manager 1, the fixed nodes 2 to 5 and the mobile nodes 6 and 7 shown in FIG. 1 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is recorded on the computer. The position detection process may be performed by reading the system and executing it. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.

  The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

It is a block diagram which shows the structure of one Embodiment of this invention. It is a block diagram which shows the structure of the fixed node 2 and the mobile node 6 which are shown in FIG. It is a flowchart which shows operation | movement of the manager 1 shown in FIG. It is a flowchart which shows operation | movement of the fixed node 2 shown in FIG. It is a flowchart which shows operation | movement of the fixed node 2 shown in FIG. It is a flowchart which shows operation | movement of the mobile node 6 shown in FIG.

Explanation of symbols

  1 ... manager, 2, 3, 4, 5 ... fixed node, 6, 7 ... mobile node

Claims (1)

(A) a communication means for transmitting and receiving radio signals;
A packet receiving means for receiving a packet including transmission time information by the communication means;
A mobile node comprising a packet transmitting means for transmitting a packet having the same content as the received packet by the communication means after a certain elapsed time from receiving the packet;
(B) a communication means for transmitting and receiving a radio signal;
Packet transmitting means for transmitting a packet including transmission time information by the communication means;
A packet receiving means for receiving, by the communication means, a packet transmitted by the mobile node;
Based on the transmission time information included in the packet received by the packet receiving means, the time information when the packet is received, and the fixed elapsed time information, a propagation time between the mobile node is obtained, A first fixed node comprising distance calculation means for obtaining a distance from the mobile node based on a propagation time;
(C) a communication means for receiving a radio signal;
Fixed node packet receiving means for intercepting a packet transmitted by the first fixed node by the communication means;
Mobile node packet receiving means for intercepting packets transmitted by the mobile node by the communication means;
Based on the time difference between the reception time of the packet received by the fixed node packet reception means and the reception time of the packet received by the mobile node packet reception means, and the distance information with respect to the first fixed node, the mobile node A plurality of second fixed nodes comprising distance calculation means for calculating the distance to
(D) Distance information between the first fixed node and the mobile node, distance information between the mobile node and the plurality of second fixed nodes calculated by each of the plurality of second fixed nodes, And a position specifying means for calculating the position of the mobile node based on the position detection system.

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