JP6191508B2 - Position measurement system - Google Patents

Description

  The present invention relates to a technique for measuring a position using sound waves.

  Conventionally, as a technique for measuring the position of a vehicle, a technique for measuring a position based on a positioning signal from an artificial satellite such as GPS (Global Positioning System) is generally used.

  By the way, as a technique for measuring the position, a technique using sound waves is also known. In Patent Document 1, a sound wave signal is emitted from a plurality of underwater fixed stations that are synchronized in time and received by a receiving device mounted on the underwater vehicle, and the sound wave signal is transmitted from the underwater fixed station. A technique (apparatus) for specifying the position of a receiving device (underwater vehicle) based on each distance between each underwater fixed station and the receiving device calculated from the transmission / reception time until reception by the receiving device is disclosed. Yes. That is, in the technique described in Patent Document 1, the intersection of a plurality of virtual spherical surfaces with the calculated distance as the radius centered on each underwater fixed station is specified as the position of the receiving device (underwater vehicle). The

JP-A-5-93773

  However, the technique described in Patent Document 1 has a problem in that the configuration is complicated because it is necessary to provide a plurality of transmission devices that transmit sound wave signals. In the configuration described in Patent Document 1, a system under measurement (underwater vehicle) for measuring a position includes a receiving device, and a measurement system (an underwater fixed station) for measuring a position includes a transmitting device. On the other hand, the position of the system to be measured can be specified by a configuration in which the system to be measured includes a transmission device and the measurement system includes a reception device. In this way, although there can be only one transmitter for transmitting the sound wave signal, it is necessary to provide a plurality of receivers for receiving the sound wave signal, which again complicates the configuration.

  The present invention has been made in view of these problems, and an object thereof is to provide a technique for performing position measurement using sound waves with a simple configuration.

  One aspect of the present invention is a position measurement system including a transmission device that is installed on a traveling path of a moving body and transmits a predetermined position measurement sound wave, and a reception device that is mounted on the moving body and receives a position measurement sound wave. The receiving device includes a traveling position detection unit. The travel position detecting means determines that the reception frequency of the position measurement sound wave is changed by the Doppler effect accompanying travel of the moving body and becomes equal to the predetermined position detection frequency in a predetermined position in the direction along the travel path. It is detected that the receiving device is located at

  According to such a configuration, the position of the moving body in the direction along the traveling path can be specified based on the reception frequency. That is, when the distance between the transmitting device and the moving body changes with the change in the position of the moving body in the direction along the traveling path, the reception frequency of the position measurement sound wave changes due to the Doppler effect. The position of the moving body in the direction can be specified from the reception frequency. Since the absolute position of the traveling path is fixed, the absolute position of the moving body can be estimated from the position of the moving body in the direction along the traveling path. Therefore, in the present invention, the position of the moving body can be measured using sound waves with a simple configuration using one transmission device and one reception device.

  Another aspect of the present invention is a receiving device that receives a predetermined position measurement sound wave that is mounted on a moving body and that is transmitted from a transmitting device that is installed on a traveling path of the moving body, and is a traveling position detection unit. Is provided. The travel position detecting means determines that the reception frequency of the position measurement sound wave is changed by the Doppler effect accompanying travel of the moving body and becomes equal to the predetermined position detection frequency in a predetermined position in the direction along the travel path. It is detected that the receiving device is located at According to such a receiving apparatus, the above-described position measurement system can be constructed, and as a result, the above-described effects can be obtained.

  In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is limited is not.

It is a block diagram which shows the structure of a position measurement system. It is a figure for demonstrating the installation position of a sound source device, and the directivity of a speaker. (A) is a figure which shows the positional relationship of a speaker and a vehicle when a vehicle approaches a speaker, (b) is the frequency of the sound wave for position measurement received in a vehicle according to the position of the vehicle with respect to a speaker. It is a figure which shows a mode that changes by. It is a flowchart of a position estimation process. It is a flowchart of a distance calculation process. It is a figure for demonstrating distance calculation, (a) is a figure which shows the transmission waveform of the sound wave for position measurement, (b) is a figure which shows the reception waveform of the sound wave for position measurement.

Embodiments to which the present invention is applied will be described below with reference to the drawings.
[1. Constitution]
A position measurement system 1 shown in FIG. 1 is a system that measures the position of a vehicle (automobile in this embodiment) traveling on a road (in this embodiment, a road) using sound waves. A sound source device 2 that transmits sound waves for use and a receiving device 10 that is mounted on the host vehicle 3 and that receives a position measurement sound wave with a microphone 12 and measures the position of the host vehicle 3.

  As shown in FIG. 2, the sound source device 2 is installed on a travel path on which the host vehicle 3 travels. In the present embodiment, as an example, the sound source device 2 is installed on the traveling road immediately after leaving the tunnel. Returning to FIG. 1, the sound source device 2 includes a GPS receiver 21, a sound source control unit 22, and a speaker 23.

The GPS receiver 21 receives a transmission signal from a GPS artificial satellite, acquires highly accurate time information (absolute time), and outputs this time information to the sound source control unit 22.
The sound source control unit 22 is configured around a known microcomputer, and executes processing for generating sound waves according to a predetermined switching pattern based on a time signal acquired by the GPS receiver 21 according to a program. In the present embodiment, as an example, sound waves are generated according to a switching pattern set to alternately switch sound waves having different frequencies (10 kHz and 12 kHz) every predetermined switching period (0.02 sec) (FIG. 6A). reference). The generated sound wave is output to the speaker 23 as a position measurement sound wave.

  The speaker 23 amplifies the position measurement sound wave output from the sound source control unit 22 and transmits it to the outside of the sound source device 2. In the present embodiment, as an example, the sound source device 2 is installed such that the speaker surface of the speaker 23 is parallel to the travel path, and the directivity of the speaker 23 is a straight line perpendicular to the direction along the travel path. Thus, it is set within a predetermined angle range (± 35 degrees) centered on a straight line (referred to as a measurement straight line) L passing through the speaker 23 of the sound source device 2 (see FIG. 2).

The directivity of the speaker 23 and the position measurement sound wave switching period are set as follows.
(1) Directivity of the speaker 23 The position measurement sound wave is received on the left side surface of the host vehicle 3 (assuming a vehicle width of 2 m) traveling in the traveling lane (the lane closest to the speaker 23 when there are a plurality of lanes). Assuming that there is a microphone 12, the microphone 12 is assumed to be 0.75m from the end of the road (assuming that the road width is 3.5m and the width of the host vehicle 3 is 2m, It is assumed that you are driving in the middle of the road). It is assumed that the speaker 23 is at a position 1 m from the end of the traveling road with the roadside band in between. That is, it is assumed that the distance a between the speaker 23 and the microphone 12 when the microphone 12 mounted on the host vehicle 3 is located on the measurement line L is 1.75 m.

  Next, it is assumed that the traveling speed of the host vehicle 3 is 200 km / h, which is higher than the maximum designed speed of the vehicle. In the present embodiment, at least one frequency switching timing (for position measurement) during the time from when the own vehicle 3 (microphone 12) enters the audible area, that is, the directivity range of the speaker 23, until it is positioned on the measurement line L. The directivity of the speaker 23 is set so as to include the timing at which the frequency of the sound wave is switched. Since the host vehicle 3 traveling at a speed of 200 km / h travels 1.12 m in 0.02 sec, the distance b in FIG. 2 is set to 1.12 m.

  Then, based on the calculated value of the directivity angle δ in FIG. 2, the directivity of the speaker 23 is set in a range of ± 35 degrees with the measurement straight line L as the center. As a result, when the vehicle travels on the road at a speed of 200 km / h or less, the position measurement sound wave including the switching timing of the position measurement sound wave is generated in the own vehicle 3 (microphone 12) before reaching the measurement straight line L. Received. Note that the directivity of the speaker 23 set in the present embodiment is merely an example, and may be set arbitrarily according to various predetermined conditions.

(2) Position Measurement Sound Wave Switching Period As an example in the present embodiment, the position measurement sound wave switching period is the travel lane (the lane farthest from the speaker 23 when there are multiple lanes). ) Is set to be equal to or greater than the distance from the speaker 23 to the microphone 12 when the position of the microphone 12 of the host vehicle 3 traveling on the measurement line L is positioned on the measurement straight line L. That is, for example, on a traveling road as shown in FIG. 2, the distance traveled by the sound wave during the switching period (when the speed of sound is 340 m / second is 6.8 m at 0.02 sec) is from the traveling road edge to the speaker 23. Distance (1 m), lane width of the left lane (3.5 m), and distance between the lane marking and the microphone 12 of the host vehicle 3 traveling in the right lane (assuming 0.75 m as in (1)) The switching period is set so as to be equal to or greater than the total value. Note that the switching period set in the present embodiment is merely an example, and may be arbitrarily set according to various predetermined conditions.

  By the way, the frequency of the sound wave for position measurement transmitted from the sound source device 2 (speaker 23) is different from the frequency of the sound wave for position measurement transmitted from the sound source device 2 (speaker 23) due to the Doppler effect. 3 can be received.

  As shown in FIG. 3A, when the host vehicle 3 is traveling at a vehicle speed u toward a measurement straight line L that is perpendicular to the direction along the traveling path and passes through the sound source (speaker 23). The frequency f of the position measurement sound wave received by the host vehicle 3 is expressed by the equation (1) as is well known.

f ₀ is the frequency of the sound wave for position measurement transmitted from the speaker 23, and V is the speed of sound. Note that the sound velocity V (m / sec) is expressed by equation (2) according to the temperature t (° C.).

That is, as shown in FIG. 3B, the frequency f of the sound wave received by the host vehicle 3 changes according to the angle θ, that is, the position of the host vehicle 3 on the travel path at that time. Here, when the angle θ is π / 2 rad, that is, when the host vehicle 3 (the microphone 12) is located on the measurement line L, the sound wave having the same frequency as the position-measurement sound wave f ₀ transmitted from the speaker 23. Is received by the host vehicle 3 (microphone 12). On the other hand, when the angle θ changes from 0 to π / 2 rad, that is, when the host vehicle 3 approaches the measurement straight line L, the host vehicle 3 depends on the position of the host vehicle 3 on the travel path at that time. The frequency f of the position-measurement sound wave received at 1 changes so as to gradually decrease to f ₀ with f ₀ (V + ucosθ) / V being the maximum value.

  In this embodiment, the frequency of the position measurement sound wave is set to 10 kHz and 12 kHz, and when the host vehicle 3 approaches the measurement line L, the frequency range that each frequency can take due to the Doppler effect is (1). ). For example, when the host vehicle 3 approaches the measurement straight line L, the range that the position measurement sound wave having a frequency of 10 kHz can take by the Doppler effect is about 11.6 kHz to 10 kHz, and the position measurement sound wave having a frequency of 12 kHz. The range that can be taken by the Doppler effect is about 13.9 kHz to 12 kHz, and both are converted so as to gradually become lower as the host vehicle 3 approaches the measurement straight line L. That is, the frequency that can be taken by the Doppler effect (referred to as the Doppler frequency) changes, but the tendency that the sound wave for position measurement at 12 kHz always changes at a higher Doppler frequency than the sound wave for position measurement at 10 kHz is changed. No.

  Further, for example, when the host vehicle 3 moves away from the measurement line L, the Doppler frequency changes so as to gradually decrease as the host vehicle 3 moves away from the measurement line L. In this case, the range that the position measurement sound wave having a frequency of 10 kHz can take from the Doppler effect is about 10 kHz to 8.4 kHz, and the range that the position measurement sound wave having a frequency of 12 kHz can take from the Doppler effect is about 12 kHz to 10.1 kHz. It is. The tendency of the 12 kHz position measurement sound wave to constantly shift at a higher Doppler frequency compared to the 10 kHz position measurement sound wave is the same.

  Here, when a position measurement sound wave that can be switched to any one of a plurality of types of transmission frequencies (here, 10 kHz and 12 kHz) is used, the reception frequency on the measurement line L is one of the transmission frequencies (for example, 10 kHz) due to the Doppler effect. ). In such a case, on the measurement line L, the other transmission frequency (12 kHz) does not change to one transmission frequency (10 kHz) due to the Doppler effect.

  That is, when a sound wave equal to one transmission frequency (10 kHz) is received when the host vehicle 3 is positioned on the measurement straight line L, a sound wave for position measurement having one transmission frequency (10 kHz) is transmitted from the sound source device 2. It can be said that Similarly, when a sound wave equal to the other transmission frequency (12 kHz) is received when the host vehicle 3 is positioned on the measurement straight line L, a sound wave for position measurement at the other frequency (12 kHz) is transmitted from the sound source device 2. It can be said that The frequency (10 kHz, 12 kHz) of the position measurement sound wave set in the present embodiment is merely an example, and may be arbitrarily set according to predetermined various conditions.

  Returning to FIG. 1, the receiving device 10 includes a GPS receiver 11, a microphone 12, a map database (map DB) 13, a speaker position database (speaker position DB) 14, a sound wave measurement database 15 (measurement sound wave DB) 15, a temperature sensor. 16, a position detection unit 17, a display unit 18, and a measurement control unit 19.

  The GPS receiver 11, like the GPS receiver 21 of the sound source device 2, receives a transmission signal from a GPS artificial satellite, acquires high-accuracy time information, and has its own vehicle (the receiving device 10 is mounted). The absolute position (latitude, longitude and altitude) of the vehicle 3) is measured. The time information and the absolute position of the host vehicle 3 are output to the measurement control unit 19. In the present embodiment, as an example, the GPS receiver 11 is installed on the inner surface (the roof side) of the windshield of the host vehicle 3, and the absolute position of the GPS receiver 11 (more precisely, the GPS reception of the GPS receiver 11). The absolute position of the antenna) is detected as the absolute position of the host vehicle 3.

The microphone 12 is installed near the front center of the hood of the host vehicle 3 as an example in the present embodiment, and outputs the received sound wave to the measurement control unit 19.
The map database (map DB) 13, the speaker position database (speaker position DB) 14, and the sound wave measurement database (sound wave measurement DB) 15 are rewritable storage devices such as a flash ROM.

The map database 13 stores map data representing a map showing roads (traveling roads) on which the host vehicle can travel.
The speaker position database 14 stores the absolute position of the sound source device 2 (speaker 23) and the absolute direction in which the travel path is located with respect to the sound source device 2 (speaker 23). The absolute azimuth here is, for example, when the sound source device 2 (speaker 23) is installed on a traveling road extending east and west, when the direction in which the traveling road is located with respect to the sound source device 2 (speaker 23) is south or This is information indicating which of the north.

  The sound wave measurement database 15 stores data such that the transmission frequency of the position measurement sound wave transmitted from the sound source device 2 (the speaker 23), the switching pattern, and the absolute time of the switching timing can be grasped. For example, this data may be data indicating in what pattern the sound wave for position measurement is transmitted from the sound source device 2 (speaker 23) based on a certain reference time. Thereby, using this data, the absolute time of the switching timing can be grasped in the position measurement sound wave transmitted from the sound source device 2 (speaker 23). In addition to these, the sound wave measurement database 15 has a transmission delay time, a reception delay time, and a position of the GPS receiver 11 on which side of the microphone 12 in the host vehicle 3 as well as to what extent. Information indicating whether or not there is a shift is stored.

The temperature sensor 16 detects the outside air temperature and outputs the detection result to the measurement control unit 19.
The position detection unit 17 includes a gyroscope 71, a vehicle speed sensor 72, and a G sensor 73.

The gyroscope 71 detects the magnitude of the rotational motion applied to the host vehicle 3 and outputs the detection result to the measurement control unit 19.
The vehicle speed sensor 72 detects the rotational speed of the axle based on the number of pulses per unit time output from the pulse generator attached to the axle of the host vehicle 3, and the speed of the host vehicle 3 is determined based on the detected rotational speed. The speed is calculated, and the calculation result is output to the measurement control unit 19.

The G sensor 73 detects the acceleration in the front-rear direction of the host vehicle 3 and outputs the detection result to the measurement control unit 19.
The display unit 18 displays, on the display screen, for example, a map image based on the map data input from the map database 13 and a mark indicating the vehicle position displayed superimposed on the map image.

  The measurement control unit 19 is configured with a known microcomputer centering on the CPU 91, ROM 92, and RAM 93. The measurement control unit 19 (specifically, the CPU 91) executes various processes based on a program stored in the ROM 92.

  The measurement control unit 19 executes, for example, processing for reading map data representing a map near the vehicle position from the map database 13 and displaying the map data on the display unit 18, processing for displaying a mark indicating the vehicle position on the map, and the like. To do. Further, the measurement control unit 19 executes a process of calculating the vehicle position by a known autonomous navigation based on each detection signal from the position detection unit 17.

  Since the detection signal (output value) of each autonomous sensor (gyroscope 71, vehicle speed sensor 72, and G sensor 73) provided in the position detection unit 17 includes an error, in autonomous navigation, these increase as the travel distance increases. Are accumulated. As a result, as is well known, the deviation (detection error) between the calculated vehicle position based on autonomous navigation and the actual (true) vehicle position increases.

  Therefore, the measurement control unit 19 executes a process of correcting the calculated host vehicle position based on a positioning signal from a GPS artificial satellite at a predetermined cycle. When the host vehicle 3 passes through the sound source device 2, a position estimation process described below is executed to correct the calculated host vehicle position.

[2. processing]
Next, the position estimation process executed by the measurement control unit 19 will be described using the flowchart of FIG. Note that the process shown in FIG. 4 is repeatedly executed while the ACC switch is on.

First, in S (step) 100, time information is acquired from the GPS receiver 11. In the present embodiment, the sound source device 2 also acquires time information using the GPS receiver 21, and by acquiring time information using the GPS receiver 11 in this step, the sound source device 2 and the reception device 10 are acquired. Time synchronization (error is 10 ⁻⁶ sec or less).

  In subsequent S105, the map database 13 and the speaker position database 14 are used on the planned travel route when it is assumed that the host vehicle 3 travels along the road from the host vehicle position (calculated host vehicle position based on autonomous navigation). The speaker 23 located closest to the calculated vehicle position is specified, and it is determined whether or not the distance to the speaker 23 is less than a predetermined distance. If it is determined that the distance is greater than or equal to the predetermined distance, the process proceeds to S100, and if it is determined that the distance is less than the predetermined distance, the process proceeds to S110.

  In S110, it is determined whether or not the position measurement sound wave from the sound source device 2 (speaker 23) is received by the microphone 12. If the position measurement sound wave is not received, the process proceeds to S100, and if the position measurement sound wave is received, the process proceeds to S115.

  In S115, it is determined whether or not the reception frequency of the position measurement sound wave received by the microphone 12 matches a predetermined position detection frequency. Here, if the frequency coincides with the predetermined position detection frequency, the process proceeds to S125, and if not, the process proceeds to S120.

  In S120, it is determined whether the sound source device 2 (speaker 23) has passed. In the present embodiment, as an example, when the reception frequency is lower than a predetermined position detection frequency, it is determined that the sound source device 2 (speaker 23) has passed. Note that whether or not the sound source device 2 (speaker 23) has passed may be determined by various methods such as determination based on the distance to the sound source device 2 (speaker 23).

  If it is determined that the sound source device 2 (speaker 23) has passed, the process proceeds to S100. If it is determined that the sound source apparatus 2 (speaker 23) has not been passed, the process proceeds to S115. That is, after the distance to the sound source device 2 (speaker 23) is less than the predetermined distance (S105; YES) and the position detection sound wave is received from the sound source device 2 (speaker 23) (S110; YES), the sound source While it is determined that the device 2 (speaker 23) has not been passed (S120; NO), the determination (S115) of whether or not the reception frequency matches the predetermined position detection frequency is repeatedly executed.

In S125, which is shifted when the reception frequency matches the predetermined position detection frequency in S115 described above, the absolute time (measurement reception time) t _Rf0 when the reception frequency matches the position detection frequency is acquired, and the _{process proceeds} to S130. Transition. In this embodiment, the position detection frequency is, for example, a position measurement sound wave transmission frequency transmitted from the sound source device 2 (speaker 23), that is, a position measurement sound wave transmission frequency stored in the sound wave measurement database 15. (10 kHz and 12 kHz).

In S130, the detection result of the temperature sensor 16 is acquired.
In subsequent S135, the outside air temperature is estimated from the detection result of the temperature sensor 16 acquired in S130, and the sound speed at the estimated outside air temperature is calculated according to the above-described equation (2).

  Next, in S140, in the sound source device 2, the time from when the sound wave for position measurement is generated by the sound source control unit 22 until it is transmitted to the outside from the speaker 23 (referred to as transmission delay time), and the sound wave for position measurement are 12 is acquired from the sound wave measurement database 15 until it is received at 12 and input to the measurement control unit 19 (referred to as reception delay time).

In subsequent S145, a distance calculation process described later is executed using the measurement reception time t _Rf0 acquired in S125, the sound speed calculated in S135, and the transmission delay time and reception delay time acquired in S140. In the distance calculation process, the fact that the reception frequency of the position measurement sound wave is changed by the Doppler effect accompanying the traveling of the host vehicle 3 and becomes equal to the position detection frequency is automatically determined at a predetermined position in the direction along the traveling path. It is detected that the vehicle 3 (the microphone 12) is located. In the present embodiment, as an example, the vehicle 3 (the microphone 12) is positioned on the measurement line L that the reception frequency of the position measurement sound wave is equal to the transmission frequency (10 kHz or 12 kHz) of the position measurement sound wave. Detect as a thing. In the distance calculation process, the distance from the sound source device 2 (speaker 23) to the own vehicle 3 (microphone 12) is calculated, and the relative position of the own vehicle 3 (microphone 12) with respect to the sound source device 2 (speaker 23) is specified. .

Next, in S150, the absolute position of the microphone 12 is calculated using the absolute position of the sound source device 2 (speaker 23) and the calculation result of S145.
In subsequent S155, the position of the host vehicle 3 is calculated using the absolute position of the microphone 12 calculated in S150. That is, when the position of the host vehicle 3 is measured based on a positioning signal from a positioning satellite such as a GPS satellite, the position of the host vehicle 3 is equal to the absolute position of the GPS receiver 11, and as described above, the GPS receiver 11. Since the microphone 12 and the microphone 12 are provided at positions apart from each other, in this step, correction is performed to convert the absolute position of the microphone 12 calculated in S150 into the absolute position of the GPS receiver 11. In the present embodiment, as an example, information indicating how much the position of the GPS receiver 11 is deviated from the position of the microphone 12 in the host vehicle 3 is stored in the sound wave measurement database 15. Is used to correct the absolute position of the microphone 12 to the absolute position of the GPS receiver 11. And the absolute position of this GPS receiver 11 is memorize | stored in a memory | storage device (for example, RAM93) as an absolute position of the own vehicle 3, the process of this step is complete | finished, and it transfers to S100. Thereafter, the same processing is repeated.

Next, the distance calculation process executed in S145 of the position estimation process will be described using the flowchart shown in FIG.
In S205, as shown in FIG. 6B, the position measurement received by the receiving device 10 when the reception frequency of the position measurement sound wave becomes equal to the position detection frequency (here, 10 kHz as an example). in waves of switching patterns, the switching timing time t _R0 corresponding points (reception switching point) a of the immediately preceding measuring reception time t _{Rf 0,} point corresponding to the measurement reception time t _{Rf 0} (reception timing point) to R The number P of waves is detected. When the position detection frequency is 10 kHz, the number of waves in the switching period of 0.02 sec is 200 waves, and when the position detection frequency is 12 kHz, it is 240 waves.

As shown in FIG. 6B, due to the above-mentioned Doppler effect, before the reception frequency of the position measurement sound wave coincides with the measurement reception time t _Rf0 , the reception frequency f of the position measurement sound wave is The frequency (f> 10 kHz) is higher than the frequency (10 kHz). Further, after the reception frequency of the position measurement sound wave coincides with the measurement reception time t _Rf0 , the reception frequency f of the position measurement sound wave is lower than the position detection frequency (10 kHz) (f <10 kHz).

Next, in S210, a time t _Tf0 (measurement transmission time) at which the reception timing point R corresponding to the measurement reception time t _Rf0 in the position measurement sound wave switching pattern is transmitted by the sound source device 2 is calculated. That is, as shown in FIG. _6A , in the switching pattern of the position measurement sound wave transmitted by the sound source device 2 (speaker 23), transmission corresponding to the switching timing time t _R0 immediately before the measurement receiving time t _Rf0. The side switching timing time t _T0 can be specified based on data stored in the sound wave measurement database 15. Here, as an example, if the reception frequency f is equal to the position detection frequency (10 kHz) as described above and the number P of waves detected in S205 is 60 + 1/4 waves, transmission for measurement is performed. The time t _Tf0 is calculated by the equation (3).

In S215, the difference between the measurement transmission time t _Tf0 and the measurement reception time t _Rf0 is calculated as the delay time SD.
In subsequent S220, the transmission delay time and the reception delay time acquired in S140 of the position estimation process are subtracted from the delay time SD calculated in S215 to correct the delay time SD to the transmission / reception time difference HD. That is, strictly speaking, the delay time SD calculated in S215 is the measurement transmission time t _Tf0 detected by the sound source control unit 22 of the sound source device 2 and the measurement reception time 19 by the measurement control unit 19 of the reception device 10. Since it is a difference from t _Rf0 , the time when the sound wave reaches the speaker 23 from the sound source controller 22 to the time when the sound wave reaches the speaker 12 (transmission delay time), and the sound wave from the microphone 12 to the measurement control unit This value includes the time to reach 19 (reception delay time). Therefore, in this step, as described above, the delay time SD is corrected to the time (the transmission / reception time difference HD) that the sound wave reaches the microphone 12 from the speaker 23 by subtracting the transmission delay time and the reception delay time.

  In step S225, the distance d between the speaker 23 and the microphone 12 is calculated by multiplying the transmission / reception time difference HD corrected in step S220 by the sound speed calculated in step S135 of the position estimation process.

  In subsequent S230, the relative position of the microphone 12 with respect to the speaker 23 is specified based on the position of the microphone 12 in the direction along the traveling path and the distance d between the speaker 23 and the microphone 12 calculated in S225. That is, in the present embodiment, the position of the microphone 12 is a straight line perpendicular to the direction along the traveling path and is on the measurement line L passing through the speaker 23, and the distance d from the speaker 23 to the microphone 12 Based on the above, the relative position of the microphone 12 with respect to the speaker 23 is specified.

[3. effect]
According to the embodiment detailed above, the following effects can be obtained.
[3A] The measurement control unit 19 indicates that the reception frequency of the position measurement sound wave is changed by the Doppler effect accompanying the traveling of the host vehicle 3 and becomes equal to the predetermined position detection frequency. It is detected that the receiving apparatus 10 is located at a predetermined position (S145).

  In such a configuration, the position of the host vehicle 3 in the direction along the travel path can be specified based on the reception frequency. That is, in the state where the host vehicle 3 is traveling along the traveling path, the sound source device 2 (speaker 23) and the receiving device 10 (microphone 12) are accompanied by a change in the position of the host vehicle 3 in the direction along the traveling path. When the distance to the position changes, the reception frequency of the position measurement sound wave changes due to the Doppler effect. For this reason, the position of the own vehicle 3 in the direction along the traveling path can be specified from the reception frequency. Therefore, the position of the host vehicle 3 can be measured using sound waves with a simple configuration using the sound source device 2 and the receiving device 10 one by one.

  [3B] The position detection frequency is the transmission frequency of the position measurement sound wave (in this embodiment, 10 kHz and 12 kHz as an example). Further, the measurement control unit 19 measures that the reception frequency is equal to the transmission frequency of the position-measurement sound wave and is a straight line perpendicular to the direction along the travel path and passes through the speaker 23 of the sound source device 2. It is detected that the receiving device 10 (microphone 12) is positioned on the straight line L (S145).

  As described above, the reception frequency of the position measurement sound wave can be changed according to the position of the receiving device 10 in the direction along the traveling path. For example, in the process in which the receiving device 10 moves away from the sound source device 2, the reception frequency changes due to the Doppler effect, and is measured when the distance between the receiving device 10 and the sound source device 2 becomes the shortest, that is, the receiving device 10 measures. At a time point on the straight line L (a time point when the receiving device 10 is located directly in front of the sound source device 2), it becomes equal to the transmission frequency (the original frequency of the sound wave for position measurement). That is, the reception frequency at this time is calculated regardless of the speed of the host vehicle 3 (see equation (1)).

  Therefore, in this embodiment in which it is detected that the reception device 10 (microphone 12) is positioned on the measurement line L that the reception frequency is equal to the transmission frequency of the position measurement sound wave, the speed of the host vehicle 3 is detected. Without this, the absolute position of the host vehicle 3 can be estimated. As a result, the configuration of the receiving device 10 in the position measurement system 1 can be simplified.

  [3C] The sound wave for position measurement is transmitted from the sound source device 2 so as to change in a predetermined pattern based on the time information. The receiving device 10 detects the measurement reception time based on the position measurement sound wave pattern using the same time information as the time information used by the sound source device 2, and estimates the measurement transmission time from the detected measurement reception time. Then, the distance from the sound source device 2 is calculated using these differences (S225). And the relative position of the receiving device 10 with respect to the sound source device 2 is specified based on the positioning of the receiving device 10 on the measurement straight line L and the calculated distance (S230). In such a configuration, by grasping the absolute position of the sound source device 2 (speaker 23) in advance, based on the specified relative position, the absolute position of the receiving device 10 (microphone 12), and eventually the vehicle 3 The absolute position can be estimated with high accuracy.

  In the present embodiment, the sound source device 2 corresponds to an example of “transmission device”, the GPS receiver 21 corresponds to an example of “acquisition unit”, and the speaker 23 corresponds to an example of “transmission unit”. The host vehicle 3 corresponds to an example of a “moving body”. Further, S145 corresponds to an example of processing as “traveling position detection means”, S100 corresponds to an example of processing as “acquisition processing means”, and S225 corresponds to an example of processing as “distance calculation means”. , S230 corresponds to an example of processing as “relative position specifying means”. The time information corresponds to an example of “time signal”.

[4. Other Embodiments]
As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that this invention can take a various form, without being limited to the said embodiment.

  [4A] In the above-described embodiment, the transmission frequencies (10 kHz, 12 kHz) of a plurality of types of position measurement sound waves have a frequency range that one transmission frequency (10 kHz) can take due to the Doppler effect and the other transmission frequency (12 kHz). Although it overlapped with the possible range, it is not limited to this. For example, as for the transmission frequencies of a plurality of types of position measurement sound waves, the frequency range that one position measurement sound wave can take due to the Doppler effect and the frequency range that the other position measurement sound wave can take due to the Doppler effect do not overlap each other. It may be set as follows.

  [4B] In the above embodiment, the position measurement sound wave is set so as to alternately switch the sound waves of two types of frequencies at a predetermined timing based on the time information. The sound waves may be set to be switched alternately. Further, the position measurement sound wave may be a sound wave that can be switched to one of a plurality of types of intensities at a predetermined timing based on time information.

  [4C] In the above embodiment, the sound source device 2 is installed on the travel path immediately after exiting the tunnel, but is not limited thereto, and may be installed, for example, under an overpass. In addition, the sound source device 2 is configured to always transmit the sound wave for position measurement, but is not limited thereto. For example, the sound source device 2 may transmit a position measurement sound wave triggered by the vehicle approaching within a predetermined distance from the sound source device 2.

  [4D] In the above embodiment, the fact that the reception device 10 (microphone 12) is positioned on the measurement line L indicates that the reception frequency is equal to a predetermined position detection frequency, that is, the transmission frequency of the position measurement sound wave. Although detected, the present invention is not limited to this, and the position detection frequency may be set to any value within the range that the transmission frequency of the position measurement sound wave can take due to the Doppler effect. However, as is clear from the equation (1) and FIG. (B), the position detection frequency has a large rate of frequency change due to the Doppler effect, and the angle θ is near π / 2 rad, in order to distinguish it from the previous and subsequent frequencies. It is more desirable that the frequency be such that.

  [4E] In the above embodiment, when it is detected that the host vehicle 3 (the microphone 12 of the receiving device 10) is positioned on the measurement line L, the speaker is based on the delay time SD of the position measurement sound wave at this time. The distance d between the microphone 23 and the microphone 12 is calculated to estimate the relative position of the receiving device 10 (the microphone 12) with respect to the sound source device 2 (the speaker 23). d may be set to a predetermined fixed value. For example, when the host vehicle 3 is traveling on a travel path as shown in FIG. 2, it is assumed that the receiving device 10 (microphone 12) is located at the center of the travel path on which the host vehicle 3 is traveling. The distance d between the speaker 23 and the microphone 12 may be set to 4.5 m. Alternatively, assuming that the host vehicle 3 is located at the center of the road on which the host vehicle 3 is traveling, the distance between the speaker 23 and the host vehicle 3 may be set to a predetermined fixed value (that is, For example, if the vehicle is traveling on a road as shown in FIG. 2, the distance between the speaker 23 and the host vehicle 3 may be set to 4.5 m). As a result, the accuracy is lower than the case of calculating based on the delay time SD of the sound wave for position measurement, but it is equal to or higher than the case of measuring the position based on the positioning signal from the artificial satellite such as GPS. The absolute position of the host vehicle 3 can be estimated with accuracy.

  [4F] In the above embodiment, the position measurement system 1 measures the position of a car traveling on a road. However, the position measurement system 1 is not limited to this, and for example, measures the position of a train traveling on a track. It may be.

  [4G] The functions of one constituent element in the above embodiment may be distributed as a plurality of constituent elements, or the functions of a plurality of constituent elements may be integrated into one constituent element. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function. Moreover, you may abbreviate | omit a part of structure of the said embodiment as long as a subject can be solved. In addition, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present invention.

  [4H] The present invention is implemented in various forms such as the above-described position measurement system 1 and the receiving apparatus 10, a program for causing a computer to function as the apparatus 10, a medium on which the program is recorded, a position measurement method, and the like. be able to.

  DESCRIPTION OF SYMBOLS 1 ... Position measuring system 2 ... Sound source device 3 ... Own vehicle 10 ... Receiver 11 ... GPS receiver 19 ... Measurement control part 21 ... GPS receiver 23 ... Speaker 91 ... CPU 92 ... ROM 93 ... RAM.

Claims (4)

A position measuring system comprising: a transmitting device (2) that is installed on a traveling path of a moving body and transmits a predetermined position measuring sound wave; and a receiving device (10) that is mounted on the moving body and receives the position measuring sound wave. (1)
The transmitter is
Acquisition means (21) for acquiring a time signal for performing time synchronization;
A transmitting means (23) for transmitting a sound wave whose frequency changes in a predetermined pattern based on the time signal, wherein the frequency changes to any one of a plurality of different frequencies, as the sound wave for position measurement; ,
With
The receiving device is:
Acquisition processing means (S100) for performing processing for acquiring the time signal;
The fact that the reception frequency of the position measurement sound wave is changed by the Doppler effect accompanying the traveling of the moving body and becomes equal to the predetermined position detection frequency is received at the predetermined position in the direction along the traveling path. Traveling position detecting means (S145) for detecting that the device is located ;
A point corresponding to the measurement reception time that is the time when the reception frequency of the position measurement sound wave becomes equal to the position detection frequency and the measurement reception time in the pattern of the position measurement sound wave is the transmission device. Distance calculation means (S225) for calculating a difference from the transmission time for measurement, which is the transmitted time, as a distance from the transmission device;
The transmitting apparatus based on the position of the receiving apparatus in the direction along the traveling path detected by the traveling position detecting means and the distance between the transmitting apparatus and the receiving apparatus calculated by the distance calculating means. And a relative position specifying means (S230) for specifying the relative position of the receiving device with respect to the position measuring system. The position measurement system according to claim 1,
The position detection frequency is a transmission frequency of the position measurement sound wave,
The travel position detection means is a straight line that is perpendicular to the direction along the travel path and that passes through the sound source of the transmission device when the reception frequency is equal to the transmission frequency of the position measurement sound wave. Detecting that the receiving device is located above the position measuring system. The position measurement system according to claim 2 ,
The transmission means transmits a sound wave that can be switched to one of a plurality of types of frequencies at a predetermined timing based on the time signal as the sound wave for position measurement. A receiving device (10) that is mounted on a moving body and receives a predetermined position measurement sound wave transmitted from a transmitting device (20) installed on a traveling path of the moving body,
The transmitter is
Acquisition means (21) for acquiring a time signal for performing time synchronization;
A transmitting means (23) for transmitting a sound wave whose frequency changes in a predetermined pattern based on the time signal, wherein the frequency changes to any one of a plurality of different frequencies, as the sound wave for position measurement; ,
With
The receiving device is
Acquisition processing means (S100) for performing processing for acquiring the time signal;
The fact that the reception frequency of the position measurement sound wave is changed by the Doppler effect accompanying the traveling of the moving body and becomes equal to the predetermined position detection frequency is received at the predetermined position in the direction along the traveling path. Traveling position detecting means (S145) for detecting that the device is located ;
A point corresponding to the measurement reception time that is the time when the reception frequency of the position measurement sound wave becomes equal to the position detection frequency and the measurement reception time in the pattern of the position measurement sound wave is the transmission device. Distance calculation means (S225) for calculating a difference from the transmission time for measurement, which is the transmitted time, as a distance from the transmission device;
The transmitting apparatus based on the position of the receiving apparatus in the direction along the traveling path detected by the traveling position detecting means and the distance between the transmitting apparatus and the receiving apparatus calculated by the distance calculating means. Relative position specifying means (S230) for specifying the relative position of the receiving apparatus with respect to the receiving apparatus.

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