JP2003279640A - System and method for detecting position of moving body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system and a method that can accurately grasp the location of each moving body in a real time, even when a large number of moving bodies exist, and that is made easily detectable the position of a specified moving body. <P>SOLUTION: A main part of this system is constituted of an ultrasonic transmitter 1 provided in the each of the plurality of moving bodies, ultrasonic receivers 2 provided in at least three portions in every area in a building, and a control computer 3 as one of processing means for finding positional information of the moving body based on a delay time D of an ultrasonic wave in an ultrasonic transmission and reception period T. The transmitter 1 is provided with ultrasonic transmission and reception requiring means 1b, 1c for assigning a starting timing t0 of the ultrasonic transmission and reception period T, and the each receiver 2 is provided with an ultrasonic transmission and reception permitting means for determining whether the starting timing t0 is effective or not to permit the start of the transmission and reception period T from the starting timing t0, when effective. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system and method for detecting the position of a moving body, and more particularly to a system and method for detecting the position of a moving body for detecting the location of each moving body in a building.

[0002]

2. Description of the Related Art Conventionally, efficient management of a moving body by detecting the location of each moving body (for example, each worker in a facility) in a building and grasping the movement of each moving body over time. There is a position detection system that is going to be useful for. According to this system, the location data of each mobile unit can be captured in real time in the PC to grasp the movement of each mobile unit in real time, and the layout of the equipment in the facility can be reviewed and changed to improve work efficiency. Can be improved. Examples of such a system include a system using infrared rays and a system using radio waves. In both systems, the first transmitter / receiver is installed in each of the plurality of moving bodies, and the second transmitter / receiver is installed in each of the plurality of moving bodies in each predetermined area in the building. The position of the moving body is detected by. First, request signals (infrared rays or radio waves) corresponding to a specific moving body are selectively transmitted from all the second transmitters / receivers.
Next, the detection signal (infrared or radio wave) is transmitted from the first transmitter / receiver of the specific mobile body that has received the request signal to the second transmitter / receiver in the area to which the mobile body belongs. And
By recognizing the second transmitter / receiver that receives the transmitted detection signal earliest, the area to which the specific moving body belongs is detected. By the way, when infrared rays are used as the detection signal,
It is easily affected by the brightness of the work site, and it is often impossible to communicate due to the effect of outdoor light. In addition, there are many restrictions on the installation location of the infrared transmitter / receiver due to the directivity of infrared rays. On the other hand, when a radio wave is used as the detection signal, a weak radio wave that does not require application is used due to its convenience, which may cause a valley due to resonance with a reflected wave or the like in the building, resulting in communication failure. In addition, there is a drawback that it is difficult to obtain accurate information due to noise generated from devices in the facility. Further, in both of the above-mentioned systems, there is a drawback in that even if the area where the moving object to be detected is located can be confirmed, it is not possible to detect the coordinate position, that is, the accurate location.

Therefore, in recent years, as a system that is not easily affected by the work environment and can detect an accurate location,
Those using ultrasonic waves have been developed and become widespread, and are disclosed in, for example, Japanese Patent Laid-Open No. 08-226810. As shown in FIG. 5, this system includes an ultrasonic wave transmitter 1 provided in each of a plurality of moving bodies (for example, a plurality of users in a facility) and an ultrasonic wave provided in a predetermined area on a ceiling in a building. Based on the receiver 2 and the ultrasonic waves received by these receivers 2, the transmitter 1 is specified, the location of each moving body is calculated, and information for specifying each moving body can be inquired. The main part is constituted by the management computer 3 as a processing means. The system operates as follows. That is, a certain transmitter 1 sequentially transmits ultrasonic waves to a plurality of receivers 2 based on a time division set in advance in time division. Then, some of the receivers 2 receive the transmitted ultrasonic waves, and the management computer 3 identifies the transmitter 1 based on the ultrasonic waves and calculates the location of each mobile body. In addition, in order to adjust the internal clock of each transmitter 1, infrared light for clock adjustment is transmitted from each receiver 2. Such a system using ultrasonic waves has small restrictions due to directivity, is not affected by strong light such as outdoor light, and has excellent properties of ultrasonic waves that do not easily interfere with each other. It can be said that it is effective even at work sites where It also has an advantage that it is less likely to be affected by noise generated from surrounding electric devices.

[0004]

However, in the above-mentioned ultrasonic position detection system, when the number of transmitters is large, the measurement for each transmitter is performed in order to secure an ultrasonic wave reception period for each transmitter in advance. The reference cycle for performing all the steps becomes longer. For example, when 30 transmitters are set, the cycle becomes as long as about 10 seconds. Therefore, it is difficult to say that the position of each moving body is detected in real time. This becomes a particular problem when it is desired to accurately investigate the movement of a specific moving body. Further, since the unidirectional communication method is adopted as the communication method, it is not possible to measure the distance of only a specific transmitter without waiting for the preset measurement order. That is, the transmitter could not transmit ultrasonic waves until the time allotted to itself was received. Furthermore, the ultrasonic wave transmission / reception period could not be started due to the operation on the transmitter side. The present invention has been made to solve the above problems, and an object of the present invention is to provide a position of a moving body that can accurately and in real time grasp the location of each moving body even if the number of moving bodies in a building is large. It is to provide a detection system and method. Another object of the present invention is to provide a position detection system and method that can detect the position of a specific moving body more easily in addition to the above-mentioned object.

[0005]

In order to achieve the above-mentioned object, the invention according to claim 1 has at least an ultrasonic transmitter provided in each of a plurality of moving bodies and at least a predetermined area in a building. The ultrasonic wave receiver is provided in three or more places, and within the ultrasonic wave transmission / reception period in which both the ultrasonic wave transmission by the ultrasonic wave transmitter and the ultrasonic wave reception by the ultrasonic wave receiver are possible. Arithmetic processing means for measuring the time required for the ultrasonic wave transmitted from the transmitter to be received by the ultrasonic receiver, executing predetermined arithmetic processing based on the required time, and obtaining position information of the moving body. In the position detection system for a mobile body consisting of, the ultrasonic transmitter comprises ultrasonic transmission / reception requesting means for designating the start time of the ultrasonic transmission / reception period from the ultrasonic receiver side, The ultrasonic receiver The machine determines whether or not the start time of the ultrasonic wave transmission / reception period designated by the ultrasonic wave transmission / reception request means is valid, and if it is valid, starts the ultrasonic wave transmission / reception period from the start time. The position detecting system for a mobile body is provided with an ultrasonic wave transmission / reception permission unit for permitting.

According to a second aspect of the present invention, in the invention according to the first aspect, the designation of the start time of the ultrasonic wave transmission / reception period by the ultrasonic wave transmission / reception requesting means of the ultrasonic transmitter is as follows. This is performed by transmitting an ultrasonic wave transmission / reception request signal to the ultrasonic wave receiver.

The invention according to claim 3 is the invention according to claim 2, wherein the ultrasonic wave transmission / reception permission means of the ultrasonic wave receiver requests ultrasonic wave transmission / reception from the ultrasonic wave transmitter. When the signal is received, the ultrasonic wave transmission / reception permission signal is transmitted to the ultrasonic wave transmitter while the ultrasonic wave transmission / reception period is started, except when a predetermined process is performed on another ultrasonic wave receiver. It is characterized by that.

Further, in the invention described in claim 4, in the invention described in claim 3, the ultrasonic wave transmission / reception requesting means of the ultrasonic wave transmitter transmits an ultrasonic wave transmission / reception request signal to the ultrasonic wave receiver. When the ultrasonic wave transmission / reception permission signal from the ultrasonic wave receiver is not obtained even after transmitting, the ultrasonic wave transmission / reception request signal is transmitted again after a certain period of time. is there.

According to a fifth aspect of the invention, in the invention according to the third or fourth aspect, the ultrasonic wave transmission / reception request signal transmitted from the ultrasonic wave transmission / reception requesting means of the ultrasonic transmitter, and The ultrasonic wave transmission / reception permission signal transmitted from the ultrasonic wave transmission / reception permission unit of the ultrasonic wave receiver is all infrared data to which information for identifying the ultrasonic wave transmitter is attached. It is a thing.

The invention according to claim 6 is the invention according to any one of claims 3 to 5, wherein the arithmetic processing executed by the arithmetic processing means transmits the ultrasonic wave transmission / reception permission signal. After calculating the distance information from the ultrasonic transmitter to the ultrasonic receiver based on the time required to receive the ultrasonic wave, the distance collected from at least three or more ultrasonic receivers. It is characterized in that it is a process of obtaining the position information of the moving body based on the information and the coordinate data of the installation position of the sound wave receiver.

Further, the invention according to claim 7 is an ultrasonic transmitter provided in each of the plurality of moving bodies, and an ultrasonic receiver provided in at least three or more locations in each predetermined area in the building. A moving body whose main part is composed of an arithmetic processing unit that obtains position information of the moving body based on the time required until the ultrasonic wave transmitted from the ultrasonic transmitter is received by the ultrasonic receiver. In the position detection system, the ultrasonic transmitter specifies a start time of an ultrasonic wave transmission / reception period in which both ultrasonic wave transmission by the ultrasonic wave transmitter and reception of the ultrasonic wave by the ultrasonic wave receiver are possible. And a step of transmitting an ultrasonic wave transmission / reception request signal for receiving the ultrasonic wave transmission / reception request signal from the ultrasonic wave transmitter, predetermined processing applied to another ultrasonic wave receiver is performed. Where it is done Except, and transmitting the ultrasonic wave emission-reception set permission signal with permitting the start of the ultrasonic wave emission-reception set period to the ultrasonic transmitter, the ultrasonic transmitters,
When the ultrasonic wave transmission / reception permission signal is received, a step of transmitting an ultrasonic wave to the ultrasonic wave receiver, and when the ultrasonic wave receiver receives the ultrasonic wave transmitted from the ultrasonic wave transmitter, the ultrasonic wave Obtaining a time required from transmitting the transmission / reception permission signal to receiving the ultrasonic wave, and calculating distance information from the ultrasonic transmitter to the ultrasonic receiver based on the required time. And a step of obtaining the position information of the ultrasonic transmitter based on the distance information and the coordinate data of the installation position of the ultrasonic receiver, the method for detecting the position of a moving body.

[0012]

1 is a block diagram schematically showing a configuration of a position detecting system for a moving body according to an embodiment of the present invention. The main part of the system of the present embodiment is configured by an ultrasonic wave transmitter 1, an ultrasonic wave receiver 2, a junction box 4, a controller 5, a management computer 3, and a cable for communication-connecting these.

As shown in FIG. 2A, the ultrasonic wave transmitter 1 is mounted on a part (on a helmet or a hat) of each of a plurality of workers (moving bodies) where the ultrasonic wave U is easily received. There is. As shown in FIG. 2B, this transmitter 1 includes an ultrasonic wave transmission unit 1a that transmits an ultrasonic wave U, and the start time of an ultrasonic wave transmission / reception period that enables both transmission and reception of the ultrasonic wave U. It is provided with an ultrasonic wave transmission / reception requesting means for designating. The ultrasonic wave transmission / reception requesting means in the present embodiment includes a position notification switch 1b and an infrared transmission / reception unit 1c.
The main part is composed of.

The ultrasonic receivers 2 are installed on the ceiling in the building in at least three locations for each predetermined area (FIG. 4). This receiver 2 is provided with an ultrasonic wave reception means (not shown) for receiving the ultrasonic waves U from the transmitter 1, and the ultrasonic wave transmission / reception request means (1b, 1c) of the transmitter 1 specifies the ultrasonic wave. An ultrasonic wave transmission / reception permission unit (not shown) is provided for judging whether or not the start time of the ultrasonic wave transmission / reception period is valid, and if it is valid, permitting the start of the ultrasonic wave transmission / reception period from the start time. ing.

The receiver 2 is communicatively connected to a management computer 3 such as a personal computer via a junction box 4 and a controller 5. Each receiver 2 is communicatively connected to a junction box 4 installed in each predetermined area via two non-polarized wires. Each of the junction boxes 4 is communicatively connected to the controller 5 via an 8-core modular cable, supplies power to the communication chip, and converts data from the controller 5 into a data format of a two-wire power transmission / reception communication method. , Or the inverse conversion function. Controller 5
Is communicatively connected to the management computer 3 via an RS-232C cable, has a function of converting a command from the management computer 3 into a predetermined data format, and a function of adjusting / controlling an internal clock of the receiver 2. have.

A predetermined calculation chip (not shown) is built in the receiver 2 and the controller 5, and a predetermined calculation program is installed in the management computer 3. These arithmetic chips and arithmetic programs have a function as arithmetic processing means for performing arithmetic processing relating to position detection. Here, the delay time (required time) until the ultrasonic wave U transmitted from the transmitter 1 is received by the receiver 2 includes information indicating how far the transmitters / receivers 1 and 2 are apart from each other. Therefore, the position information can be calculated by performing the predetermined calculation processing by the calculation processing means based on this.

FIG. 3 shows a timing chart for explaining the procedure for detecting the position of the moving body by the system having the above-mentioned configuration. Hereinafter, with reference to this figure, the description will be made with an emphasis on the fact that the transmitter / receiver available period T in which both transmission and reception of the ultrasonic waves U are possible can be designated from the transmitter 1.

Upon receiving a request from the operator, the ultrasonic wave transmitter 1 transmits an ultrasonic wave transmission / reception request signal R for designating the start time t0 of the transmission / reception period T. Specifically, when the operator pushes the position notification switch 1b, infrared data having information for identifying the transmitter 1 is transmitted from the infrared transmitter / receiver 1c to the ultrasonic transmitter 2. . As described above, since the position can be detected due to the operation from the moving body side, even if the number of the moving bodies is large, the position detection for the specific moving body can be performed in real time. In addition, the transmitter 1 is used as the request signal R.
By using the infrared data to which the information for specifying is added, it is possible to improve the adaptability to changes in the measurement environment (for example, the number of moving bodies) and the degree of freedom in system design.

Next, when the ultrasonic wave transmission / reception permission means of the receiver 2 receives the request signal R from the transmitter 1, the ultrasonic wave transmission / reception permission means except for the case where the predetermined processing of the other receivers 2 is performed. At the same time as starting the transmission / reception period T from the start time t0, the ultrasonic transmission / reception permission signal P (infrared data with information for identifying the transmitter 1 that transmitted the request signal R)
Is transmitted to the transmitter 1. By excluding the case where the predetermined processing is performed on the other receivers 2 as described above, it is possible to deal with the case where the position notification switches 1b of the plurality of transmitters 1 are pressed almost at the same time. Further, by starting the ultrasonic wave reception period T and transmitting the permission signal P, the load of execution processing is reduced. Furthermore, the permission signal P
By using the infrared data to which the information for identifying the transmitter 1 is added, it is possible to improve the adaptability to environmental changes and the variety of system designs. In addition,
The transmission / reception period T may be started after a certain period of time has passed after the permission signal P is transmitted, or the permission signal P may include information on the start time t0 of the transmission / reception period T to start the transmission / reception period. The transmission / reception period T may be started from t0.

Next, the transmitter 1 transmits the ultrasonic wave U from the ultrasonic wave transmitter 1a at the same time as receiving the permission signal P from the receiver 2 by the infrared transmitter / receiver 1c. FIG. 4 shows how the ultrasonic wave U at this time is transmitted from the transmitter 1 to the receiver 2. By using the ultrasonic wave as the detection signal in this manner, various advantages of the conventional system as shown in FIG. 5 can be secured. The timing of transmitting the ultrasonic waves U may be changed as appropriate according to the setting of the receiver 2. For example, the ultrasonic waves U may be transmitted after a certain time has elapsed after receiving the permission signal P. Good.

Next, when the receiver 2 receives the ultrasonic wave U transmitted from the transmitter 1, the receiver 2 measures the delay time D from the transmission of the permission signal P to the reception of the ultrasonic wave U. Distance information from the transmitter 1 to the receiver 2 is calculated based on the delay time D. This distance information is collected by the controller 5 at regular time intervals I. By such arithmetic processing based on the delay time D and collective processing by the controller 5, accurate position detection can be performed while keeping the arithmetic processing load low.

Then, the management computer 3 performs a calculation process for obtaining position information of each moving body based on the distance information calculated by at least three receivers 2 and the coordinate data of the installation position of the receiver 2. Run. Further, the management computer 3 processes the calculated position information into mapping information so that the temporal movement of each moving body can be grasped at a glance. Here, the coordinate data is numerical data stored in the storage medium of the management computer 3 as a database. In addition, the receiver 2, the controller 5,
Also, the arithmetic processing by the management computer 3 may be configured to be collectively executed by the management computer 3. Further, it is most effective to execute each arithmetic process continuously and in real time, but it may be executed at regular time intervals in consideration of the load of each arithmetic process.

In addition to the above configuration, the transmitter 1 is the receiver 2
If the permission signal P from the receiver 2 is not obtained even if the request signal R is transmitted to the receiver, the request signal R is transmitted again after a certain period of time. As a result, even if the position notification switches 1b of a plurality of transmitters are pressed almost at the same time, it is possible to cope with the situation and ensure accurate position detection.
That is, in the lower part of FIG. 3, as shown about the case where the position notification switch 1b of the transmitter 1-1 is pressed and the position notification switch 1b of the transmitter 1-2 is pressed soon,
Although the permission signal for the first request signal R1 from the transmitter 1-2 is not obtained, the permission signal P2 for the second request signal R2 transmitted after a lapse of a certain time thereafter.
I know that I was able to get. Even in such a case, the accuracy of the position detection of the moving body can be ensured by performing the arithmetic processing by the management computer 3 only when at least three or more pieces of distance information are obtained.

Since the position detecting system for a moving body in this embodiment described above has a feature in a so-called arbitrary measurement mode in which ultrasonic measurement can be performed at arbitrary timing according to a request from the transmitter side, this arbitrary system is used. Although the case where only the measurement mode is executed has been described in detail, FIG.
The position detection may be performed by using the so-called automatic measurement mode and the arbitrary measurement mode described above in the conventional system shown in FIG. In this case, it is preferable that the position detection is normally executed in the automatic measurement mode, and the mode is switched to the arbitrary measurement mode by an interrupt from the transmitter side.

Although both the request signal R and the permission signal P in the present embodiment are optical signals, the present invention is not limited to this, and either one or both may be electrical signals.

[0026]

As described above, in the moving body position detecting system and method of the present invention, the ultrasonic transmitters provided in each of the plurality of moving bodies and at least three or more locations for each predetermined area in the building. From an ultrasonic receiver provided and an arithmetic processing means for obtaining position information of the moving body based on a time required until the ultrasonic wave transmitted from the ultrasonic transmitter is received by the ultrasonic receiver. In the mobile body position detection system, the position of the mobile body can be detected due to the operation from the mobile body side (the ultrasonic transmitter side). As a result, while maintaining the advantages of the conventional position detection system using ultrasonic waves, even when the number of moving bodies in the building is large, the location of each moving body can be accurately grasped in real time and a specific movement can be performed. The position of the body can be detected more easily.

[Brief description of drawings]

FIG. 1 is a block diagram showing a concept of a position detecting system for a moving body of the present invention.

2 is an external perspective view showing a mounting form (a) of the ultrasonic transmitter of FIG. 1 on a moving body and a configuration (b) thereof.

3 is a timing chart for explaining a procedure for detecting the position of a moving body by the system of FIG.

4 is a schematic perspective view showing the ultrasonic transmitter and the ultrasonic receiver of FIG. 1. FIG.

FIG. 5 is a block diagram showing the concept of a conventional moving body position detection system.

[Explanation of symbols]

1 ultrasonic transmitter 1a Ultrasonic wave transmitter 1b Position notification switch 1c infrared transceiver 2 ultrasonic receiver 3 management computer 4 junction box 5 controller I Data collection cycle T Ultrasonic wave transmission / reception period D Required time (delay time) R Ultrasonic wave transmission / reception request signal (infrared data) P Ultrasonic wave transmission / reception permission signal (infrared data) U ultrasound

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takamichi Yoshikawa             Omori, 6-17-10 Minamioi, Shinagawa-ku, Tokyo             Rainbow Building 8th floor Aioi Co., Ltd.             In the system (72) Tomoko Sekine, Inventor             Omori, 6-17-10 Minamioi, Shinagawa-ku, Tokyo             Rainbow Building 8th floor Aioi Co., Ltd.             In the system F term (reference) 5J083 AA03 AB14 AC11 AC17 AC29                       AD02 AD04 AF01 AF04 AG02                       AG05 BA01 BB07 CA03

Claims (7)

[Claims] 1. An ultrasonic wave transmitter provided in each of a plurality of moving bodies, an ultrasonic wave receiver provided in at least three locations for each predetermined area in a building, and an ultrasonic wave generator Required until the ultrasonic wave transmitted from the ultrasonic transmitter is received by the ultrasonic receiver within the ultrasonic wave transmission / reception period in which both transmission and reception of the ultrasonic wave by the ultrasonic receiver are possible. A position detecting system for a mobile body, which comprises a calculation processing means for measuring time and executing predetermined arithmetic processing based on this required time to obtain position information of the mobile body, wherein the ultrasonic transmitter is the An ultrasonic wave transmission / reception request unit for designating the start time of an ultrasonic wave transmission / reception period from the ultrasonic wave receiver side, wherein the ultrasonic wave receiver is the ultrasonic wave designated by the ultrasonic wave transmission / reception request unit. Sending and receiving Position of the moving body, characterized by comprising ultrasonic transmission / reception permission means for judging whether or not the start timing of the period is valid, and if it is valid, permitting the start of said ultrasonic transmission / reception period from the start timing Detection system. 2. The ultrasonic transmitter / receiver requesting means of the ultrasonic transmitter specifies the start time of the ultrasonic transmitter / receiver period by transmitting an ultrasonic transmitter / receiver request signal to the ultrasonic receiver. The position detection system for a mobile body according to claim 1. 3. When the ultrasonic wave transmission / reception permission unit of the ultrasonic wave receiver receives the ultrasonic wave transmission / reception request signal from the ultrasonic wave transmitter, predetermined processing for other ultrasonic wave receivers is performed. The position detection system for a mobile body according to claim 2, wherein the ultrasonic wave transmission / reception period is started and an ultrasonic wave transmission / reception permission signal is transmitted to the ultrasonic wave transmitter except when the ultrasonic wave transmission / reception period is started. 4. The ultrasonic wave transmission / reception requesting means of the ultrasonic wave transmitter transmits the ultrasonic wave transmission / reception request signal from the ultrasonic wave receiver even if the ultrasonic wave transmission / reception request signal is transmitted to the ultrasonic wave receiver. 4. When not obtained, the ultrasonic wave transmission / reception request signal is transmitted again after a certain period of time.
The position search system for the moving body described. 5. The ultrasonic wave transmission / reception request signal transmitted from the ultrasonic wave transmission / reception requesting means of the ultrasonic wave transmitter, and the ultrasonic wave transmission / reception permission transmitted from the ultrasonic wave transmission / reception permission means of the ultrasonic wave receiver. The position detection system for a moving body according to claim 3 or 4, wherein each of the signals is infrared data to which information for identifying the ultrasonic transmitter is attached. 6. The calculation processing executed by the calculation processing means is performed by the ultrasonic transmitter from the ultrasonic transmitter based on a time required from the transmission of the ultrasonic transmission / reception permission signal to the reception of the ultrasonic waves. The distance information to the sound wave receiver is calculated, and the position information of the moving body is obtained based on the distance information collected from at least three ultrasonic wave receivers and the coordinate data of the installation position of the sound wave receiver. The position detection system for a mobile body according to any one of claims 3 to 5, which is a process. 7. An ultrasonic wave transmitter provided in each of a plurality of moving bodies, an ultrasonic wave receiver provided in at least three or more locations for each predetermined area in a building, and an ultrasonic wave transmitter transmitted from the ultrasonic wave transmitter. In a position detecting system for a moving body, the main part of which is composed of an arithmetic processing unit that obtains position information of the moving body based on the time required until ultrasonic waves are received by the ultrasonic receiver, An ultrasonic transmission / reception request signal for designating the start time of an ultrasonic transmission / reception period that enables both the transmission of ultrasonic waves by the ultrasonic transmitter and the reception of the ultrasonic waves by the ultrasonic receiver. The step of transmitting, the ultrasonic receiver, when receiving the ultrasonic transmission and reception request signal from the ultrasonic transmitter, unless a predetermined process is performed on other ultrasonic receivers, Ultrasonic wave transmission / reception period The step of transmitting an ultrasonic wave transmission / reception permission signal to the ultrasonic wave transmitter while permitting the start of, and the ultrasonic wave transmitter receives the ultrasonic wave transmission / reception permission signal, and ultrasonic waves are transmitted to the ultrasonic wave receiver. And a step of transmitting the ultrasonic wave, when the ultrasonic wave receiver receives the ultrasonic wave transmitted from the ultrasonic wave transmitter, the time required from the transmission of the ultrasonic wave transmission / reception permission signal to the reception of the ultrasonic wave And a step of calculating distance information from the ultrasonic transmitter to the ultrasonic receiver based on the required time, in the distance information and coordinate data of the installation position of the ultrasonic receiver. And a step of obtaining position information of the ultrasonic transmitter based on the method.