JPH07140241A - Locating system for moving body - Google Patents

Abstract

PURPOSE:To locate a moving body within a building by determining the two-dimensional position of the moving body using first and second ultrasonic transmitting devices arranged apart from each other and first and second ultrasonic receiving devices which are mounted on the moving body. CONSTITUTION:An ultrasonic transmitter-receiver 33 receives an ultrasonic pulse signal SPA transmitted by the ultrasonic transmitter 23 of an ultrasonic transmitting device A, and outputs a reception signal to a time measuring circuit 34. The circuit 34 starts counting outputs of a clock pulse generator 31 when receiving a measuring pulse signal mPB generated by a measuring pulse generator 32, and stops counting when receiving the reception signal from the receiver 33, and terminates measuring time. Thereby the distance required for an ultrasonic wave to propagate over the distance between the devices A, B is transmitted to a transmitter circuit 35. The circuit 35 transmits the time to a relay device U. The device U is disposed in each room and receives the ultrasonic wave propagation time from the device B and the ultrasonic wave propagation time and an identification code from an ultrasonic receiving device M carried by a person in each room, and sends them to a surveillance system S.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device for a moving body suitable for determining the position of a person, an article or the like existing inside a building or the like.

[0002]

As is well known, a bar code system, a magnetic card system, an electronic tag system, etc. are used to control the movement of a moving body such as a person or an article entering or leaving a building or the like. ing. In these systems, a bar code, a magnetic card, an electronic tag and the like are provided in a moving body, and the information is detected and discriminated by a sensor arranged inside a building or at a doorway.

[0003]

By the way, in a conventional system for managing the movement of a moving body inside or in a building or the like, whether or not the target moving body exists within the sensing range of the sensor. It has only the function of detecting whether or not the vehicle has passed the checkpoint, and cannot know the position of the moving body. So, for example, when a call comes in to a particular person, even though they know that they are somewhere on the large floor, they don't know where they are on the floor. It was difficult to build a system that automatically transfers a call to a phone near a person.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a position detecting device for a moving body capable of detecting the position of a moving body such as a person or an article existing inside a building or the like. To aim.

[0005]

According to a first aspect of the present invention, there is provided a position detecting device for a moving body, which is arranged so as to be spaced apart from each other, and which emits identifiable first and second ultrasonic pulse signals in synchronization with each other. First and second ultrasonic wave transmitting devices, an ultrasonic wave receiving device mounted on a moving body and receiving the first and second ultrasonic wave pulse signals, and the first and second ultrasonic wave transmitting devices From the first and second ultrasonic wave transmission devices of the moving body based on the propagation time until the first and second ultrasonic pulse signals transmitted from the ultrasonic wave reception device are received by the ultrasonic wave reception device. And a calculation means for calculating a two-dimensional position of the moving body.

According to a second aspect of the present invention, there is provided a position detecting device for a moving body,
The position detecting device for a moving body according to claim 1, wherein when the position of the moving body is obtained, a sound velocity is obtained by measuring a time period during which an ultrasonic wave propagates between reference points having known distances, and the sound velocity is obtained. Using the first, the second ultrasonic pulse signal from the propagation time until the ultrasonic receiving device is received by the first, the distance from the second ultrasonic transmitting device of the moving body, the movement It is characterized by finding the two-dimensional position of the body.

[0007]

According to another aspect of the present invention, in the position detecting device for a moving body, the first and second ultrasonic wave transmitting devices arranged apart from each other are synchronized with each other at a constant time interval and are identifiable.
A second ultrasonic pulse signal is emitted. The ultrasonic receiving device mounted on the moving body takes the time required for the ultrasonic pulse signals of the first and second stages to propagate from the first and second ultrasonic transmitting devices to the ultrasonic receiving device, respectively. measure. Then, in the calculating means, the first,
The distance from the second ultrasonic wave generation device to the ultrasonic wave reception device is calculated, and the two-dimensional position of the moving body on which the ultrasonic wave reception device is mounted is obtained.

According to another aspect of the present invention, there is provided a position detecting device for a moving body, in which, when the position of the moving body is obtained, a sound velocity is obtained by measuring a time during which an ultrasonic wave propagates between reference points having known distances. Calculate the distance from the first and second ultrasonic generators to the ultrasonic receiver from the propagation times of the ultrasonic pulse signals of the first and second units using the speed of sound, and mount the ultrasonic receiver. The two-dimensional position of the moving body is calculated.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the moving body position detecting apparatus of the present invention will be described below. First, the operating principle (basic principle) of this apparatus will be described with reference to FIG.

As shown in FIG. 3, the ultrasonic waves transmitted from ultrasonic wave transmitting devices (hereinafter referred to as transmitting devices or devices) A and B, which are spaced apart from each other in a two-dimensional space, are attached to the moving body. It will be described that the two-dimensional position of the moving body on which the receiving device M is mounted can be obtained by measuring the time of propagation to the ultrasonic receiving device (hereinafter abbreviated as receiving device or device) M. It should be noted that it is assumed that the spatial distribution of temperature, humidity, etc. is so small that it can be ignored and that there is no wind in the positions where the transmitters A and B are arranged and the entire range in which the moving body can move. Here, the transmitter A,
The distance l _AB between B is known, and the distances l _AM , l _BM from the transmitters A and B to the receiver M are unknown. And
Times at which the ultrasonic waves propagate at the distances l _AB , l _AM, and l _BM are t _AB , t _AM, and t _BM , respectively. Further, a perpendicular is drawn from the position of the receiver M to a line segment connecting the transmitters A and B, and the foot of the perpendicular is set to the position P. Then, the distance from the receiving device M to the position P is l _PM, and the time during which the ultrasonic wave propagates the distance l _PM is t _PM . Similarly, the distance from the transmitter A to the position P is l _AP , and the time during which the ultrasonic wave propagates the distance l _AP is t _AP.
And _AP, the distance from the transmitter B to the position P l _BP, the distance l _BP ultrasound time to propagate a t _BP.

Based on the above assumption, the distance l between two points is
Is proportional to the time t at which the ultrasonic wave propagates through the distance l, and the following two equations are obtained based on the Pythagorean theorem in a right triangle. t _PM ² = t _BM ² −t _BP ² (Equation 1) t _PM ² = t _AM ² −t _AP ² (Equation 2) Further, since the position P is on the line segment connecting the transmitters A and B, t _AB = t _AP + t _BP (Equation 3) holds, and this Equation 3 is modified to obtain the following Equation 4. t _BP = t _AB −t _AP (Formula 4) From Formula 1 and Formula 2, t _BM ² −t _BP ² = t _AM ² −t _AP ² (Formula 5) If Formula 4 is substituted into Formula 5, the following formula is obtained. 6 is obtained. t _AP = (t _AM ² −t _BM ² + t _AB ² ) / (2t _AB ) (Equation 6) Therefore, if t _AM , t _BM and t _AB are known, from Equation 6 to t _AP
Is obtained, and from this t _AP and the measured t _AB , t is calculated by Equation 4.
_BP is required. Furthermore, the calculated t _AP or t _BP
From the measured t _AM or t _BM ,
Alternatively, t _PM can be _calculated by Equation 1. That is, t
By measuring _AM , t _BM and t _AB , the position (coordinates) of the receiving device M with respect to the transmitting device A or B is represented by the propagation time (t _PM , t _AP ) or (t _PM , t _BP ) of the ultrasonic wave. be able to.

An embodiment of a position detecting device for a moving body of the present invention which operates based on the above-mentioned basic principle will be described below with reference to FIGS. 1, 2 and 4 to 6. FIG. 1 is a block diagram showing a configuration of a position detecting device for a moving body which is an embodiment of the present invention, and FIG. 2 is a conceptual diagram showing a situation in which the device is actually used. The position detecting device for a moving body includes ultrasonic wave transmitting devices A and B, an ultrasonic wave receiving device M, a relay device U,
As shown in FIG. 2, the ultrasonic wave transmitters A and B and the relay device U are arranged in each room R so as to move in each room R, and one room R. Each person (moving body) who can move from the room to the other room R wears the ultrasonic receiving device M. Here, each of the relay devices U ... Arranged in each of the plurality of rooms R ... Is provided with a unique identification code corresponding to the room R in which each of the plurality of rooms R is disposed. Also, a unique identification code corresponding to the person wearing each is attached.
It should be noted that the spatial distribution of temperature, humidity, etc. in each room is so small that it can be ignored, and it is assumed that there is no wind.

As shown in FIG. 1, the ultrasonic transmitter A has a clock pulse generator 21 and a measurement pulse generator 2.
2 and an ultrasonic transmitter 23. The clock pulse generator 21 generates a basic clock pulse which is the basis of time measurement based on the crystal oscillator 24, and outputs the generated basic clock pulse to the measurement pulse generator 22. The measurement pulse generator 22 generates a measurement pulse signal mp _A having a cycle of, for example, 200 ms based on this basic clock pulse, and outputs it to the ultrasonic transmitter 23. Then, the ultrasonic transmitter 23 generates the ultrasonic pulse signal sp _A each time it receives the measurement pulse signal mp _A , and transmits and outputs the ultrasonic pulse signal sp _A to the entire area of the room where the ultrasonic transmitter A is arranged. In this device A, the waveform of the measurement pulse signal mp _A output by the measurement pulse generator 22 is shown in the upper part of FIG. 5A, and the waveform of the ultrasonic pulse signal sp _A output by the ultrasonic transmitter 23 is shown in FIG. ) Are shown below.

The ultrasonic wave transmission device B comprises a clock pulse generator 31, a measurement pulse generator 32, an ultrasonic wave transmitter / receiver 33, a time measuring circuit 34, and a transmitting circuit 35. Then, the ultrasonic transmitter A described above
In the same manner as in the configuration in 1, the clock pulse generator 31 generates and outputs the basic clock pulse based on the crystal oscillator 36, and the measurement pulse generator 32 outputs the measurement pulse signal mp _B having a cycle of 200 ms based on the basic clock pulse. The ultrasonic wave transmitter / receiver 33 generates and outputs the measurement pulse signal mp.
Each time _B is received, an ultrasonic pulse signal sp _B is generated and transmitted and output to the entire room. In this device B, the waveform of the measurement pulse signal mp _B output by the measurement pulse generator 32 is shown in the upper part of FIG. 5B, and the waveform of the ultrasonic pulse signal sp _B output by the ultrasonic transceiver 33 is shown in FIG. ) Are shown below. As shown in FIG. 5 (a) and FIG. 5 (b) described above, the measurement pulse generator 2 of the ultrasonic transmitter A is used.
2 generated measurement pulse signal mp _A and ultrasonic transmitter B
Measurement pulse signal mp generated by the measurement pulse generator 32 of
It is perfectly synchronized with _B. Further, as will be described later, in the ultrasonic receiver M, the ultrasonic pulse signal sp _A transmitted from the transmitter _A and the ultrasonic pulse signal sp B transmitted from the transmitter _B are distinguished from each other so as to be distinguished from each other. The sound pulse signals sp _A and sp _B have different frequencies.

The ultrasonic transmitter / receiver 33 receives the ultrasonic pulse signal sp _A transmitted by the ultrasonic transmitter 23 of the transmitter _A , and outputs the received signal to the time measuring circuit 34. The time measurement circuit 34 starts counting the output of the clock pulse generator 31 from the time when it receives the measurement pulse signal mp _B generated by the measurement pulse generator 32, and the basic operation at the time when it receives the reception signal from the ultrasonic transmitter / receiver 33. The clock pulse counting is stopped and the time measurement is completed. As a result, the time t _AB required for the ultrasonic wave to propagate through the distance l _AB between the transmitters A and B is detected, and the result is sent to the transmission circuit 35.
The transmission circuit 35 puts this measurement result on the radio wave and transmits it to the relay device U.

The ultrasonic receiver M includes an ultrasonic receiver 4
1, a filter circuit 42, and a clock pulse generator 43
And a measuring pulse generator 44, a time measuring circuit 45, and a transmitting circuit 46. This receiving device M
In the same manner as in the transmitting devices A and B described above,
Based on the crystal oscillator 47, the clock pulse generator 43 generates a basic clock pulse and outputs it to the measurement pulse generator 44 and the time measuring circuit 45. The measurement pulse generator 44 has a cycle of 200 ms based on this basic clock pulse. The measurement pulse signal mp _M is generated and supplied to the time measuring circuit 45. Then, as shown in FIG.
And a measurement pulse generator 2 that configures each of the receiver M
2, 32 and 44 generate measurement pulse signals mp _A , m
p _B and mp _M are perfectly synchronized. Note that FIG.
In the figure, T indicates the period 200 ms of the measurement pulse signals mp _A , mp _B and mp _M.

The ultrasonic receiver 41 receives the ultrasonic pulse signals sp _A and sp _B transmitted from the transmitters A and B, respectively, and sends the received ultrasonic pulse signals sp _A and sp _B to the filter circuit 42. Filter circuit 42 includes a first filter for receiving the ultrasonic pulse signal sp _A from transmitter A, a second filter for receiving the ultrasonic pulse signal sp _B from transmitter B In this case, the signals are separated from the signals sent from the ultrasonic receiver 41, the signal FA is received when the ultrasonic pulse signal sp _A from the transmitter _A is received, and the ultrasonic pulse signal sp _B from the transmitter _B is received. In that case, the signal FB is output to the time measuring circuit 45, respectively. The time measuring circuit 45 is similar to the time measuring circuit 34 in the transmitting device B described above, and the measuring pulse generator 4
Upon receiving the measurement pulse signal mp _M from 4, the clock pulse counting, that is, the time measurement is started, and the time t _AM until the signal FA arrives and the time t _BM until the signal FB arrives are detected. In this device M, the waveform of the measurement pulse signal mp _M output by the measurement pulse generator 44 is shown in the upper part of FIG. 6, and the waveforms of the ultrasonic pulse signals sp _A and sp _B received by the ultrasonic receiver 41 are shown in the lower part of FIG. Are shown respectively. As shown in this figure, the propagation time t _{AM of the} ultrasonic wave from the transmitter A to the receiver M, and the transmitter B to the receiver M.
And the propagation time t _{BM of the} ultrasonic waves up to
_AM and t _BM are sent to the transmission circuit 46. The transmission circuit 46 attaches an identification code to the propagation times t _AM and t _BM of the ultrasonic waves to identify whether they are the propagation times from the devices A to M or the devices B to M, respectively. Along with the identification code of M itself, it is transmitted on the radio wave to the relay device U.

As described above, the relay device U is arranged in each room, and the ultrasonic wave propagation time t _AB is transmitted from the transmitting device B and the ultrasonic wave propagation time is transmitted from the receiving device M carried by a person in the room. It receives t _AM and t _BM , their identification codes, and the identification code of the apparatus M itself, and attaches the identification code of the relay apparatus U itself to these and transmits them to the monitoring apparatus S.

The monitoring device S comprises a receiving circuit 51, a signal processing circuit (arithmetic means) 52, and a display device 53. The receiving circuit 51 receives the signal from the relay device U and sends it to the signal processing circuit 52. The signal processing circuit 52 calculates the speed of sound in the room by dividing the known distance l _AB at the ultrasonic wave propagation time t _AB, and the ultrasonic wave propagation times t _AM and t _BM are calculated as the sound speed.
And the distances l _AM and l _BM are calculated. Based on the calculated distances l _AM and l _BM and the known distance l _AB , the position of the receiving device M is obtained and output to the display device 53. Then, the display device 53 displays the position of the receiving device M.

According to such a position detecting device for a moving body, each room R ₁ , R _2, ...
Alternatively, the positions of a plurality of persons (reception devices M ₁ , M ₂ ...) Having moved from one room R to another room R can be grasped by the monitoring device S, and for example, each person can be displayed on the screen of the display device 53. The position can be drawn, searched, and tracked. It is also possible to construct a system that automatically transfers a call to a telephone closest to the current position of the person when receiving a call addressed to a person carrying the receiver M. Further, this position detecting device for a moving body can be easily configured because the position detecting method is simple, and can be provided at low cost.

In the above embodiment, the measuring pulse generator 2 built in the transmitters A and B and the receiver M is incorporated.
The period T of the measurement pulse signals generated by 2, 32, and 44 is set to 200 ms.
The ultrasonic pulse signals sp _A and sp _B transmitted from the device may be set to an appropriate value that is longer than the time required for reaching the receiving device M. That is, when the distance from the transmitters A and B to the receiver M is about 30 m at maximum, the cycle T is 200.
ms or more.

Further, the measurement pulses generated by the measurement pulse generators 22, 32 and 44 incorporated in the transmitters A and B and the receiver M are assumed to be perfectly synchronized.
It may be necessary to correct the synchronization as the operating time of the position detecting device for the moving body becomes longer. In this case, for example, with reference to one of the measurement pulse generators 22 or 32 incorporated in the transmitters A and B respectively, a signal is sent between the transmitters A and B by a wire, and the reception provided in the mobile body. A radio wave signal may be wirelessly sent to the device M for correction. Of course, it is possible to make corrections between the transmitters by using the radio wave signal, and an appropriate method may be selected according to the situation.

Furthermore, as an example, the ultrasonic pulse signals sp _A and sp _B transmitted from the ultrasonic transmitters A and B have different frequencies as means for making them distinguishable in the ultrasonic receiver M. As described above, an appropriate means such as modulation and coding may be adopted.

The configuration of the transmitter B is changed to the time measuring circuit 3
4 and the transmission circuit 35 are not provided, and when the ultrasonic pulse signal sp _A transmitted from the device A is received by the ultrasonic transceiver 33 of the device B, the ultrasonic pulse signal sp _B2 is again transmitted from the device B. By causing the receiving device M to receive the ultrasonic pulse signal sp _B2 transmitted from the device B for the second time, the ultrasonic wave at this point propagates the distance l _AB between the transmitting devices A and B. It is also possible to measure the required time t _AB . In the receiver M in this case, the measurement pulse signal mp _M output by the measurement pulse generator 44
7 is shown in the upper part of FIG. 7, and the waveforms of the ultrasonic pulse signals sp _A , sp _B and sp _B2 received by the ultrasonic receiver 41 are shown in the lower part of FIG. In this case, the time t _AB and its identification code are added to the information transmitted from the receiving device M to the relay device U in addition to the information described in the above embodiment.

Further, in this case, the receiving device M can also have a calculating means built therein to calculate the sound velocity and the distances l _AM and l _BM to obtain its own position, and transmit the result to the relay device U. If the receiving device M is also provided with a display device,
Not only when the position of the device M is obtained by the arithmetic means incorporated in the device M, but also when the position of the device M is obtained by the external monitoring device S, the result is retransmitted to the device M so that the device M can obtain the result. You can check your position.

The above embodiment is a case where the present invention is applied in a two-dimensional space, but it is also possible to detect a three-dimensional position of a moving body by adding a new ultrasonic wave transmission device. That is, as shown in FIG. 8, the ultrasonic wave transmitters A, B, and C are arranged and used at three separate locations that do not exist on a straight line and used to obtain the three-dimensional position of the moving body including the receiver M. You can Also in this case, the propagation time of the ultrasonic wave is measured to measure the distance l between the transmitters A, B and C and the receiver M.
_The procedure for _{obtaining AM} , 1 _BM , and 1 _CM is similar to that for obtaining the above-mentioned two-dimensional position, and the known distances 1 _AB between transmitters A and B, distances 1 _BC between C and 1 _BC and A , C distance l
_Together with _AC , the three-dimensional position of the receiving device M is obtained.

In the position detecting device for a mobile body described above, the ultrasonic waves reaching the receiving device M are transmitted by the transmitting devices A and B.
Alternatively, in addition to the direct wave that directly arrives from C, there may be a reflected wave that arrives after being once reflected by a wall surface or the like. However, of the direct wave and the reflected wave, the direct wave naturally reaches the receiving device M first. The two ultrasonic waves can be easily distinguished in the receiving device M. That is, the ultrasonic pulse signal first received after the generation of the measurement pulse signal may be adopted.

The reason for using ultrasonic waves as a signal for time measurement is that when measuring a signal propagation time of a relatively short distance such as inside a building, a signal with a high propagation speed (a propagation speed of about 30) is measured. This is because it is difficult to perform time measurement with sufficient accuracy when 10,000 km / s) is used, and the sound velocity (about 340 m / s) is slower than that, and it can be said that the value is appropriate. Further, when the generators A and B are arranged in a plurality of rooms in a building as in the above embodiment, when electromagnetic waves are used as signals, the electromagnetic waves have high wall transparency, and therefore the generators arranged in adjacent rooms. Although the signals transmitted from the same are apt to be duplicated and malfunction occurs, this problem does not occur when ultrasonic waves are used as signals because the ultrasonic waves have low wall permeability. Further, there is a legal problem in transmitting an electromagnetic wave with a large output, but an ultrasonic wave is a sound wave that exceeds the audible range and can be transmitted with a large output (especially in a frequency range of 100 kHz to 1 MHz). It can cover a wide range.

As an application example, the position detecting apparatus for a moving body of the present invention can be used as an intrusion alarm by adding a receiving apparatus and a Doppler signal discriminator to one transmitting apparatus. In other words, the receiving device receives the reflected wave of the ultrasonic wave emitted from the transmitting device in the time zone in which no person is supposed to be present in the area where this intrusion alarm device is placed (such as indoors), and the Doppler signal discriminator detects that ultrasonic wave. When it is confirmed that the reflector that reflects the sound wave is moving, it can be used as a device that determines that someone has entered and issues an alarm. For example, during a daytime event is being held at an event venue, the position detecting device for a moving body of the present invention is used for the original purpose of tracking the position of a person carrying a receiving device, and at night, in the venue. Can be used as an intrusion alarm during times when no person should be present.

[0030]

As described above, according to the position detecting device for a moving body of the present invention, the following effects can be obtained. That is, the position detecting device for a moving body according to claim 1 is capable of discriminating first and second ultrasonic pulse from the first and second ultrasonic wave transmitting devices arranged apart from each other. The ultrasonic wave receiving device mounted on the moving body emits a signal, measures the time required for these ultrasonic pulse signals to propagate to the ultrasonic wave receiving device, and the calculating means calculates the moving time based on these propagation times. Since the position of the moving body is obtained, it is possible to search and track the position of the moving body that moves momentarily inside the building or the like. Further, even when there are a plurality of moving bodies, it is possible to individually search and track by attaching an identification code to the ultrasonic receiving device attached to each moving body. Further, even when the moving body moves in a plurality of areas, the first and second ultrasonic wave transmitting devices and the relay device with a unique identification code are arranged in the respective regions, and the relay devices are connected to the monitoring device. If information is transmitted, it is possible to search for and track a moving body over a plurality of areas.

In the moving body position detecting apparatus according to the second aspect, when the position of the moving body on which the ultrasonic wave receiving apparatus is mounted is obtained, the time for the ultrasonic wave to propagate between the reference points whose distances are known is measured. The sound velocity is obtained by calculating the distance from the ultrasonic transmitter to the ultrasonic receiver, so even if the sound velocity changes due to changes in temperature etc. The position of the body can be obtained with high accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a position detection device for a moving body that is an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a situation in which the present apparatus is used.

FIG. 3 is a diagram showing a positional relationship between first and second ultrasonic wave transmitting devices and an ultrasonic wave receiving device.

FIG. 4 is a diagram showing output waveforms of measurement pulse signals in the first and second ultrasonic transmitters and ultrasonic receivers.

FIG. 5 is a diagram showing an output waveform of a measurement pulse signal and an output waveform of an ultrasonic pulse signal in the first and second ultrasonic transmission devices.

FIG. 6 is a diagram showing an output waveform of a measurement pulse signal and a waveform of an ultrasonic pulse signal received in the ultrasonic receiving device.

FIG. 7 is a diagram illustrating an output waveform of a measurement pulse signal in the ultrasonic receiving device and the received ultrasonic wave when the ultrasonic receiving device measures a time period during which the ultrasonic wave propagates between the first and second ultrasonic transmitting devices. It is a figure which shows the waveform of a pulse signal.

FIG. 8 is a diagram showing a positional relationship between first, second and third ultrasonic wave transmitting devices and an ultrasonic wave receiving device.

[Explanation of symbols]

 A ultrasonic wave transmission device B ultrasonic wave transmission device M ultrasonic wave reception device U relay device S monitoring device T period mp measurement pulse signal sp ultrasonic pulse signal 52 signal processing circuit (arithmetic means)

Claims (2)

[Claims] 1. A first and a second ultrasonic wave transmission device, which are arranged apart from each other, are synchronized with each other, and transmit identifiable first and second ultrasonic wave pulse signals, and are mounted on a moving body. And an ultrasonic receiving device that receives the first and second ultrasonic pulse signals, and the first and second ultrasonic waves that are transmitted from the first and second ultrasonic transmitting devices at fixed time intervals. Based on the propagation time until the pulse signal is received by the ultrasonic receiver, the distance from the first and second ultrasonic transmitters of the moving body is obtained, and the two-dimensional position of the moving body is obtained. A position detecting device for a moving body, comprising: a computing means. 2. The position detecting device for a moving body according to claim 1, wherein, when obtaining the position of the moving body, the sound velocity is determined by measuring the time taken for the ultrasonic wave to propagate between reference points whose distances are known. Obtained, from the propagation time until the first and second ultrasonic pulse signals are received by the ultrasonic receiving device using the sound velocity, the distance of the moving body from the first and second ultrasonic transmitting devices And a two-dimensional position of the moving body, the position detecting apparatus for the moving body.