JP2017044563A - Terminal device, self-position measuring method, program, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a terminal device capable of improving the measurement accuracy of a self-position on the basis of information obtained from an on-vehicle device by communication between a pedestrian and a vehicle.SOLUTION: A terminal device performs radio communication with a plurality of, favorably at least three, on-vehicle devices mounted on vehicles, and obtains positional information on the respective on-vehicle devices. One example of radio communication is Wi-Fi direct communication. The terminal device calculates distance from each on-vehicle device on the basis of the electric field strength of a radio wave received by radio communication. Then, the terminal device measures a self-position, i.e. the position of the terminal device itself on the basis of the positional information on the plurality of on-vehicle devices and distance from the plurality of on-vehicle devices.SELECTED DRAWING: Figure 9

Description

  The present invention relates to inter-vehicle communication technology.

  2. Description of the Related Art So-called inter-vehicle communication is known in which wireless communication is performed between an in-vehicle device mounted on a vehicle and a terminal device possessed by a pedestrian. Patent Document 1 describes a system that performs communication between a vehicle communication device mounted on a vehicle and a pedestrian communication device possessed by a pedestrian.

JP 2014-225069 A

  In the method of Patent Document 1, a dedicated terminal is required on the pedestrian side in order to perform communication with the vehicle side. In this regard, it is convenient if inter-vehicle communication can be performed using a general-purpose terminal device such as a smartphone.

  Also, recent terminal devices are equipped with a GPS positioning device, and it is possible to measure its own position. However, since the positioning accuracy of GPS is easily affected by the environment in which the terminal device is located, it is not always possible to measure the self-position with high accuracy.

  Examples of the problem to be solved by the present invention include the above. An object of this invention is to provide the terminal device which can improve the measurement precision of a self-position based on the information acquired from the vehicle equipment by inter-step communication.

  The invention according to claim 1 is a terminal device, and performs radio communication with a plurality of vehicle-mounted devices, thereby acquiring information acquisition means for acquiring position information of the plurality of vehicle-mounted devices, and radio waves received by the wireless communication. The self-position is measured based on the distance calculation means for calculating the distance to the plurality of vehicle-mounted devices, the positional information of the plurality of vehicle-mounted devices, and the distance to the plurality of vehicle-mounted devices based on the electric field strength of Measuring means.

  The invention described in claim 7 is a self-position measurement method executed by a terminal device, and an information acquisition step of acquiring position information of the plurality of in-vehicle devices by performing wireless communication with the plurality of in-vehicle devices. A distance calculating step for calculating a distance from the plurality of on-vehicle devices based on an electric field strength of a radio wave received by the wireless communication; position information on the plurality of on-vehicle devices; and a distance from the plurality of on-vehicle devices. And a measuring step of measuring the self-position based on the above.

  The invention according to claim 8 is a program executed by a computer mounted on a terminal device, and obtains position information of the plurality of in-vehicle devices by performing wireless communication with the plurality of in-vehicle devices. Means, distance calculation means for calculating the distance to the plurality of vehicle-mounted devices based on the electric field strength of the radio wave received by the wireless communication, position information of the plurality of vehicle-mounted devices, and distance to the plurality of vehicle-mounted devices. Based on the above, the computer is made to function as a measuring means for measuring the self-position.

The structure of the communication system between steps based on an Example is shown typically. It is a block diagram which shows the structure of a vehicle equipment. It is a block diagram which shows the structure of the communication apparatus mounted in a vehicle equipment. It is a block diagram which shows the structure of a terminal device. The example of a mark displayed on a vehicle equipment and a terminal unit is shown. An example of the situation near an intersection is shown. The example of a display of the vehicle equipment in the condition shown in FIG. 6 is shown. The example of a display of the terminal device in the condition shown in FIG. 6 is shown. The situation at the time of measuring the self-position of a terminal device is shown. The principle which measures the self-position of a terminal device is shown.

  In one preferred embodiment of the present invention, the terminal device wirelessly communicates with a plurality of in-vehicle devices to obtain information acquisition means for acquiring position information of the plurality of in-vehicle devices, and a radio wave received by the wireless communication. The self-position is measured based on the distance calculation means for calculating the distance to the plurality of vehicle-mounted devices, the positional information of the plurality of vehicle-mounted devices, and the distance to the plurality of vehicle-mounted devices based on the electric field strength of Measuring means.

  The terminal device described above performs wireless communication with a plurality of, preferably at least three on-vehicle devices mounted on the vehicle, and acquires position information of each on-vehicle device. An example of wireless communication is WiFi direct communication. Further, the terminal device calculates the distance from each on-vehicle device based on the electric field strength of the radio wave received by wireless communication. Then, the terminal device measures its own position, that is, the position of the terminal device itself, based on the position information of the plurality of in-vehicle devices and the distance from the plurality of in-vehicle devices.

  In general, in-vehicle devices such as navigation devices measure the current position using various sensors in addition to GPS, and detect their own position with high accuracy even in areas where the GPS reception environment is not good. . Therefore, the measurement accuracy of the self-position of the terminal device can be improved by measuring the self-position based on the position information acquired from the plurality of on-vehicle devices and the distance from the on-vehicle devices.

  In one aspect of the terminal device, the information acquisition unit acquires the speed of the vehicle on which the in-vehicle device is mounted from the plurality of in-vehicle devices, and the measurement unit is traveling at a speed equal to or higher than a certain speed. Position information acquired from an in-vehicle device mounted on a vehicle and / or an in-vehicle device transmitting a communication wave with an electric field strength smaller than a predetermined value is not used for the measurement of the own position. Radio waves received from in-vehicle devices mounted on vehicles running at relatively high speeds or in-vehicle devices transmitting communication waves with small electric field strength have large variations in electric field strength, and are calculated distances from in-vehicle devices. It is easy to include errors. Therefore, the accuracy of the self-position to be measured is ensured by not using the position information provided from such an in-vehicle device.

  Another aspect of the above terminal device includes a GPS positioning unit, and the measurement unit measures the self-position when the positioning accuracy of the GPS positioning unit is equal to or lower than a predetermined allowable accuracy. In this aspect, if the positioning accuracy by the GPS positioning means exceeds the allowable accuracy, the GPS positioning means measures the self-position, and if the positioning accuracy is below the allowable accuracy, the position information of the plurality of on-vehicle devices and the distance to them are Measure self-position based on.

  According to another aspect of the above terminal device, display control means for displaying a mark indicating the position of the plurality of vehicle-mounted devices and the self-location on a map on a display based on the position information of the plurality of vehicle-mounted devices. Prepare. In this aspect, the position of the vehicle-mounted device and the position of the terminal device itself existing within the wireless communication range can be displayed on the map.

  In another aspect of the above terminal device, the information acquisition unit is configured to obtain, from the in-vehicle device, the attribute of the driver of the in-vehicle device, information indicating the behavior of the vehicle equipped with the in-vehicle device, The provided information including at least one of the input messages is acquired, and the display control means displays the acquired provided information on the display unit. In this aspect, it is possible to receive the attributes of the driver of the vehicle-mounted device, information indicating the behavior of the vehicle equipped with the vehicle-mounted device, a message input to the vehicle-mounted device, and the like and display it on the terminal device.

  In another embodiment of the present invention, a self-position measurement method executed by a terminal device includes an information acquisition step of acquiring position information of the plurality of in-vehicle devices by performing wireless communication with the plurality of in-vehicle devices, Based on the distance calculation step of calculating the distance to the plurality of vehicle-mounted devices based on the electric field strength of radio waves received by wireless communication, the position information of the plurality of vehicle-mounted devices, and the distance to the plurality of vehicle-mounted devices. And a measuring step for measuring the self-position. This method can also improve the measurement accuracy of the self-position of the terminal device.

  In another preferred embodiment of the present invention, a program executed by a computer installed in a terminal device acquires information for acquiring position information of the plurality of vehicle-mounted devices by performing wireless communication with the plurality of vehicle-mounted devices. Means, distance calculation means for calculating the distance to the plurality of vehicle-mounted devices based on the electric field strength of the radio wave received by the wireless communication, position information of the plurality of vehicle-mounted devices, and distance to the plurality of vehicle-mounted devices. Based on the above, the computer is caused to function as measurement means for measuring the self-position. By executing this program on the computer of the terminal device, it is possible to improve the self-position measurement accuracy of the terminal device. This program can be stored in a storage medium and handled.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[System configuration]
FIG. 1 shows a schematic configuration of an inter-pedal communication system according to an embodiment of the present invention. As illustrated, the inter-pedal communication system includes an in-vehicle device 100 mounted on the vehicle 2 and a terminal device 200 possessed by a pedestrian. The in-vehicle device 100 is typically a navigation device, and in the present embodiment, the in-vehicle device 100 is a navigation device. The terminal device 200 is typically a smartphone. In FIG. 1, for convenience of explanation, two in-vehicle devices 100 and one terminal device 200 are illustrated, but actually, the inter-pedal communication system includes a larger number of in-vehicle devices 100 and terminal devices 200. Composed.

  As shown in FIG. 1, the in-vehicle device 100 and the terminal device 200 are WiFi-Direct (registered trademark) (hereinafter referred to as “WiFi Direct” (registered trademark)), which is wireless communication using WiFi (registered trademark). Thus, wireless communication is performed directly without using a server or the like. On the other hand, the in-vehicle devices 100 mounted on the vehicle 2 may similarly communicate using WiFi Direct, and communicate based on a dedicated inter-vehicle communication standard (for example, using the 760 MHz band of the ITS dedicated frequency). Vehicle-to-vehicle communication, etc.) may be performed.

[In-vehicle device]
FIG. 2 shows a configuration of the in-vehicle device 100 that is a navigation device. The in-vehicle device 100 includes a self-supporting positioning device 10, a GPS receiver 18, a system controller 20, a disk drive 31, a data storage unit 36, a communication interface 37, a communication device 38, a display unit 40, an audio output unit 50, and an input device 60. Prepare.

  The autonomous positioning device 10 includes an acceleration sensor 11, an angular velocity sensor 12, and a distance sensor 13. The acceleration sensor 11 is made of, for example, a piezoelectric element, detects vehicle acceleration, and outputs acceleration data. The angular velocity sensor 12 is composed of, for example, a vibrating gyroscope, detects the angular velocity of the vehicle when the vehicle changes direction, and outputs angular velocity data and relative azimuth data. The distance sensor 13 measures a vehicle speed pulse composed of a pulse signal generated with the rotation of the vehicle wheel.

  The GPS receiver 18 receives radio waves 19 carrying downlink data including positioning data from a plurality of GPS satellites. The positioning data is used to detect the absolute position of the vehicle from latitude and longitude information.

  The system controller 20 includes an interface 21, a CPU 22, a ROM 23 and a RAM 24, and controls the entire in-vehicle device 100.

  The interface 21 performs an interface operation with the acceleration sensor 11, the angular velocity sensor 12, the distance sensor 13, and the GPS receiver 18. From these, vehicle speed pulses, acceleration data, relative azimuth data, angular velocity data, GPS positioning data, absolute azimuth data, and the like are input to the system controller 20. The CPU 22 controls the entire system controller 20. The ROM 23 includes a nonvolatile memory (not shown) in which a control program for controlling the system controller 20 is stored. The RAM 24 stores various data such as route data preset by the user via the input device 60 so as to be readable, and provides a working area to the CPU 22.

  A system controller 20, a disk drive 31 such as a CD-ROM drive or a DVD-ROM drive, a data storage unit 36, a communication interface 37, a display unit 40, an audio output unit 50, and an input device 60 are mutually connected via a bus line 30. It is connected to the.

  The disk drive 31 reads and outputs content data such as music data and video data from a disk 33 such as a CD or DVD under the control of the system controller 20. The disk drive 31 may be either a CD-ROM drive or a DVD-ROM drive, or may be a CD and DVD compatible drive.

  The data storage unit 36 is composed of, for example, an HDD and stores various data used for navigation processing such as map data and facility data.

  The communication device 38 includes, for example, an FM tuner, a beacon receiver, a mobile phone, a dedicated communication card, and the like, and is congested delivered from a VICS (registered trademark) (Vehicle Information Communication System) center via the communication interface 37. Receive road traffic information such as traffic information and other information. Furthermore, in the present embodiment, the in-vehicle device 100 uses the communication device 38 to perform inter-vehicle communication, inter-vehicle communication, and the like.

  FIG. 3 shows a configuration of a communication device 38 for performing inter-vehicle communication, inter-vehicle communication, and the like. The communication device 38 includes an antenna 381, a WiFi module 382, an inter-vehicle communication processing unit 383, an antenna 384, a receiver 385, an inter-vehicle communication processing unit 386, and a car I / F processing unit 387. The step-to-step communication processing unit 383 performs step-to-step communication between the terminal device 200 or the vehicle-mounted device 100 of another vehicle 2 via the antenna 381 and the WiFi module 382. The WiFi module 382 is a WiFi module compatible with WiFi Direct.

  The vehicle-to-vehicle communication processing unit 386 performs vehicle-to-vehicle communication with the other in-vehicle device 100 via the antenna 384 and the receiver 385. The receiver 385 is a dedicated receiver for inter-vehicle communication using, for example, a 760 MHz band. In addition, the car I / F processing unit 387 receives signals from the vehicle 2 such as travel speed, direction indication (right / left turn), and brake.

  Returning to FIG. 2, the display unit 40 displays various display data on a display device such as a display under the control of the system controller 20. Specifically, the system controller 20 reads map data from the data storage unit 36. The display unit 40 displays the map data read from the data storage unit 36 by the system controller 20 on a display screen such as a display. The display unit 40 includes a graphic controller 41 that controls the entire display unit 40 based on control data sent from the CPU 22 via the bus line 30 and a memory such as a VRAM (Video RAM), and can display image information that can be displayed immediately. A buffer memory 42 that temporarily stores, a display control unit 43 that controls display of a display 44 such as a liquid crystal display or a CRT (Cathode Ray Tube) based on image data output from the graphic controller 41, and a display 44 are provided. . The display 44 is composed of, for example, a liquid crystal display device having a diagonal of about 5 to 10 inches and is mounted near the front panel in the vehicle.

  The audio output unit 50 is a D / A converter that performs D / A conversion of audio digital data sent from the CD-ROM drive 31, DVD-ROM 32, RAM 24, or the like via the bus line 30 under the control of the system controller 20. 51, an amplifier (AMP) 52 that amplifies the audio analog signal output from the D / A converter 51, and a speaker 53 that converts the amplified audio analog signal into sound and outputs the sound into the vehicle. Yes.

  The input device 60 includes keys, switches, buttons, a remote controller, a voice input device, and the like for inputting various commands and data. The input device 60 is disposed around the front panel and the display 44 of the main body of the in-vehicle electronic system mounted in the vehicle. When the display 44 is a touch panel system, the touch panel provided on the display screen of the display 44 also functions as the input device 60.

[Terminal device]
FIG. 4 shows a schematic configuration of the terminal device 200. The terminal device 200 is typically a smartphone, and includes an antenna 201, a WiFi module 202, a control unit 203, a display unit 204, a GPS positioning unit 205, and a storage unit 206.

  The antenna 201 and the WiFi module 202 perform wireless communication with the in-vehicle device 100 using WiFi direct. The WiFi module 202 is a WiFi module compatible with WiFi Direct.

  The control unit 203 includes a CPU and the like, and controls the entire terminal device 200. The display unit 204 is configured by a liquid crystal display or the like, and displays various types of information acquired by inter-step communication such as the self-position of the terminal device 200 and the position of the vehicle 2 on which the in-vehicle device 100 is mounted, as will be described later.

  The GPS positioning unit 205 measures the self-position of the terminal device 200 using GPS. The storage unit 206 stores a program executed by the control unit 203 in advance. That is, the control unit 203 controls the terminal device 200 by executing a program stored in the storage unit 206. Specifically, when performing inter-pedestrian communication described later, the control unit 203 executes a dedicated application for WiFi Direct stored in the storage unit 206. The storage unit 206 is also used as a work memory when the control unit 203 performs various controls for the operation of the terminal device 200.

  In the above configuration, the antenna 201 and the WiFi module 202 function as information acquisition means in the present invention, and the control unit 203 functions as distance calculation means, measurement means, and display control means in the present invention.

[Inter-vehicle communication]
(1) Communication Method Next, a method for inter-pedal communication in the embodiment will be described. As described above, the inter-vehicle communication in this embodiment is performed by wireless communication using WiFi direct.

  Specifically, the in-vehicle device 100 compresses and embeds various types of information (hereinafter also referred to as “provided information”) to be transmitted in the WiFi Direct device ID, and transmits the information by broadcast (that is, an unspecified number). (Hereinafter also referred to as “unspecified communication”). As a result, the terminal device 200 existing in the WiFi direct communication area from the in-vehicle device 100 as the transmission source receives the device ID transmitted from the in-vehicle device 100 and decrypts (decompresses) the provided information included in the device ID. , Providing information can be acquired. Moreover, by embedding provided information in the WiFi Direct device ID and broadcasting as described above, the in-vehicle device 100 can communicate with an unspecified number of terminal devices 200 without authentication work. That is, the terminal device 200 on the receiving side does not require an authentication operation in order to receive and acquire the broadcast provided information.

  The terminal device 200 can send provided information by broadcast to the in-vehicle device 100 existing in the communication area by WiFi direct, that is, can perform unspecified communication.

  In addition, the terminal device 200 can acquire information of only a specific sender by designating address information such as a MAC address of the in-vehicle device 100 that is a transmission source (hereinafter referred to as “specific communication”). .

  Similarly, the in-vehicle device 100 can acquire information of only a specific sender (specific communication) by designating address information such as the MAC address of the terminal device 200 that is a transmission source.

  By using WiFi Direct in this way, communication can be performed simply by installing a dedicated application for WiFi Direct communication in the terminal device 200 such as a smartphone.

(2) Provision information Next, provision information transmitted and received by inter-pedal communication will be described. The provided information is compressed and transmitted to an arbitrary description area of a predetermined capacity in the WiFi Direct device ID. Therefore, various types of information can be transmitted within a predetermined capacity range.

  First, basically, the provided information includes the position information of the in-vehicle device 100 or the terminal device 200 that is the transmission source. Thereby, the in-vehicle device 100 or the terminal device 200 that is the transmission source can inform the transmission destination of its own position.

  Further, a message input by the user can be transmitted as the provision information. Specifically, by broadcasting a message input by the user of the in-vehicle device 100 or the terminal device 200 as the providing information, the information can be transmitted to the drivers and pedestrians of the surrounding vehicle all at once. For example, the user of the in-vehicle device 100 or the terminal device 200 conveys various information such as traffic jams, accidents, disasters, construction, emergency services, traffic regulations, and the like occurring in the vicinity of the driver or pedestrian of the surrounding vehicle. be able to. On the other hand, by specifying a transmission destination and transmitting a message, messages can be exchanged like a simple transceiver between the driver of the vehicle 2 and a pedestrian carrying the terminal device 200.

  The in-vehicle device 100 or the terminal device 200 can also transmit the provided information including its own attribute information. For example, in addition to the attribute information “vehicle” indicating that the vehicle is a vehicle, the vehicle-mounted device 100 includes information such as “beginner”, “elderly”, and “disabled” as attribute information of the driver of the vehicle. Can be sent. In addition to the attribute information “pedestrian” indicating that the terminal device 200 is a pedestrian, the terminal device 200 transmits information such as “children”, “elderly”, and “disabled” as pedestrian attribute information. can do.

  FIG. 5 shows an example of a mark when the in-vehicle device 100 or the terminal device 200 receives and displays these attribute information. Each attribute information is defined as a code in parentheses, and is transmitted by being included in the provided information. For example, when the terminal device 200 transmits “pedestrian” as pedestrian attribute information, a code “00” is included in the provided information, and the in-vehicle device 100 transmits “beginner” as driver attribute information. Includes the code “11” in the provided information.

  The provided information transmitted from the in-vehicle device 100 can include information indicating the behavior of the vehicle (hereinafter also referred to as “driving information”). As the driving information, for example, the traveling speed of the vehicle, right / left turn, brake information, and the like can be transmitted.

  Further, when a route to the destination is set in the in-vehicle device 100, the route information may be included in the provided information and transmitted to the terminal device 200. For example, when a certain vehicle 2 is waiting at a station with a pedestrian, a route to the station is set in the in-vehicle device 100 of the vehicle 2. Therefore, if route information is transmitted from the vehicle-mounted device 100 of the vehicle 2 to the mobile terminal 200 of the pedestrian, the pedestrian can know what route the vehicle is coming in, and if necessary, It is also possible to wait for the vehicle to move to a place where the vehicle is likely to stop on the longitude.

(3) Display Example Next, an example in which provided information is transmitted and received by inter-pedal communication will be described. In the following example, not only the inter-vehicle communication between the vehicle-mounted device 100 of the vehicle 2 and the pedestrian terminal device 200, but also the communication between the pedestrian terminal devices 200 and the vehicle of the vehicle-mounted device 100 of the vehicle 2 It is assumed that inter-vehicle communication is also performed. Note that the inter-vehicle communication between the in-vehicle devices 100 may be performed using communication using WiFi Direct, but may be performed using a dedicated receiver or module for inter-vehicle communication.

  Assume that a certain intersection is in the situation shown in FIG. Specifically, the vehicle C1 enters the intersection from the west side, and the vehicle C2 travels behind the vehicle C1. The vehicle C3 is heading from the east side to the intersection. Furthermore, the pedestrian P1 is on the south side of the intersection, and the pedestrian P2 is on the north side of the intersection. Note that the driver of the vehicle C1 is picked up by the pedestrian P1.

  FIG. 7 shows an example of a display screen displayed on the display 44 of the vehicle-mounted device 100 of the vehicle C1 in this case. First, on the display screen of the vehicle C1, the vehicle position mark M1 indicating the position of the vehicle C1 is displayed on the map. Further, since the vehicles C2 and C3 are transmitting their vehicle positions by unspecified communication, a mark M2 indicating the position of the vehicle C2 and a mark M3 indicating the position of the vehicle C3 are displayed on the display screen of the vehicle C1. ing. Since the vehicle C2 transmits the driver attribute information “beginner” as provided information, the mark M2 is a mark indicating that the driver is a beginner.

  Further, the terminal device 200 of the pedestrian P1 includes attribute information indicating “child” in the provided information and transmits it by unspecified communication, and a mark M4 indicating “child” is displayed on the display screen of the vehicle C1. ing. Furthermore, the terminal device 200 of the pedestrian P1 specifies the vehicle-mounted device 100 of the vehicle C1 as a transmission destination, and transmits the message “Come to meet” by specific communication, and the display screen of the vehicle C1 displays the walking A message “Come to meet me” is displayed near the mark M4 indicating the person P1.

  Furthermore, the pedestrian P2 includes attribute information indicating “elderly” in the provided information and transmits it by unspecified communication, and a mark M5 indicating “elderly” is displayed on the display screen of the vehicle C1. .

  FIG. 8 shows an example of a display screen displayed on the display unit 204 of the terminal device 200 of the pedestrian P1 in this case. First, the self-position of the terminal device 200 of the pedestrian P1 is displayed as a mark M6 on the display screen of the pedestrian P1. Further, since the terminal device 200 of the pedestrian P1 receives unspecified communication from the vehicles C2, C3 and the pedestrian P2 similarly to the vehicle C1, the display screen of the pedestrian P1 is similar to FIG. A mark M2 indicating the vehicle C2, a mark M3 indicating the vehicle C3, and a mark M5 indicating the pedestrian P2 are displayed.

  Further, since the vehicle-mounted device 100 of the vehicle C1 transmits its own vehicle position by unspecified communication, a mark M7 indicating the vehicle C1 is displayed on the display screen of the pedestrian P1. Furthermore, the vehicle-mounted device 100 of the vehicle C1 specifies the pedestrian P1 as the transmission destination, and transmits the message “Wait there” by specific communication, and the mark M7 indicating the vehicle C1 is displayed on the display screen of the pedestrian P1. The message "Wait there" is displayed near.

  As described above, various types of information can be transmitted and received and shared among surrounding users by unspecified communication using WiFi Direct. If specific communication is performed, information can be provided and messages can be exchanged with a specific user.

(4) Measurement of self-position Next, measurement of the self-position of the pedestrian terminal device 200 will be described. As shown in FIG. 4, the terminal device 200 measures its own position by the GPS positioning unit 205. However, the measurement accuracy of the pedestrian's own position by GPS is significantly deteriorated in the city center due to the influence of buildings and the like, and GPS positioning is not possible in the underground. In contrast, the vehicle-mounted device 100 of the vehicle 2 uses various sensors 11 to 13 in addition to the GPS receiver 18 and performs map matching, so that the positioning accuracy of the self-location is high even in a building town or the like. In addition, it is possible to measure an accurate position to some extent even in the basement. That is, in the building district and underground, the positioning accuracy of the self-position of the terminal device 200 by GPS is low, but the positioning accuracy of the vehicle position of the vehicle 2 is maintained higher than that.

  Therefore, the terminal device 200 can improve the self-position measurement accuracy by receiving the position information transmitted from a plurality of (at least three) vehicles by the above-mentioned inter-vehicle communication and measuring the self-position ( Hereinafter, this method is referred to as “self-position measurement by inter-vehicle communication”.

  FIG. 9 is a schematic diagram illustrating a method of self-position measurement by inter-pedal communication. Now, as shown in FIG. 9, the terminal device 200 receives the position information of the vehicles 2a to 2c from the terminal devices 100a to 100c mounted on the three vehicles 2a to 2c by inter-step communication. Here, as shown in FIG. 10, the position of the vehicle 2a is (Xa, Ya, Za), the position of the vehicle 2b is (Xb, Yb, Zb), and the position of the vehicle 2c is (Xc, Yc, Zc), and the position of the terminal device 200 is (x, y, z). “X” and “x” indicate latitude, “Y” and “y” indicate longitude, and “Z” and “z” indicate altitude.

  Further, the terminal device 200 detects the distance between each of the vehicles 2a to 2c and the terminal device 200 based on the electric field strength of the communication wave (radio wave) received via the antenna 201 during the inter-vehicle communication. Specifically, a map showing the correspondence between the communication distance by WiFi direct and the electric field intensity of the communication wave is created in advance, and the communication distance is determined using the map from the electric field intensity of the communication wave received by the terminal device 200. What is necessary is just to calculate. The distance between the mobile terminal 200 and the vehicle 2a obtained in this way is “Da”, the distance between the mobile terminal 200 and the vehicle 2b is “Db”, and the distance between the mobile terminal 200 and the vehicle 2c is “Dc”.

Thus, when the positions of the three vehicles 2a to 2c and the distances from the portable terminal 200 to the three vehicles 2a to 2c are obtained, the following equations can be created.
Da = {(Xa−x) ² + (Ya−y) ² + (Za−z) ² } ^1/2 (1)
Db = {(Xb−x) ² + (Yb−y) ² + (Zb−z) ² } ^1/2 (2)
Dc = {(Xc−x) ² + (Yc−y) ² + (Zc−z) ² } ^1/2 (3)
By solving these three simultaneous equations, the position (x, y, z) of the terminal device 200 can be calculated.

  As described above, when the terminal device 200 is in a building street or underground, the accuracy by GPS is lowered. In such a case, the self-position of the terminal device 200 is highly accurate by self-position measurement by inter-vehicle communication. Can be measured. Specifically, the terminal device 200 may detect the positioning accuracy by the GPS positioning unit 205 and perform the self-position measurement by the above-described communication between the pedestrians when the accuracy falls below a predetermined allowable accuracy. Alternatively, the self-position measurement by the inter-vehicle communication is always performed, and the self-position obtained by the self-position measurement by the inter-vehicle communication is used when the positioning accuracy by the GPS positioning unit 205 falls below the allowable accuracy. May be. Thereby, for example, in a building district or underground, if the position information is acquired from three or more vehicles in the vicinity, the terminal device 200 can obtain a self-position with higher accuracy than GPS.

  In addition, when the positioning accuracy falls below the allowable accuracy, the position information obtained by the self-position measurement by the inter-vehicle communication is not replaced with the position information obtained by the GPS, but the self-position measurement by the inter-vehicle communication is performed. The position information obtained by GPS may be corrected using the position information obtained in step (1).

  In the above self-position measurement by inter-vehicle communication, it is necessary to acquire position information of three or more vehicles. However, as the number of surrounding vehicles providing the position information increases, the position of the position obtained by the measurement becomes larger. Accuracy is improved.

  On the other hand, when position information can be acquired from a large number of vehicles, it is preferable to perform self-position measurement by the above-described inter-vehicle communication using position information considered to be more accurate. For example, since the communication wave received from a vehicle in which the terminal device 200 is traveling at a relatively high speed has a larger variation in electric field strength than the communication wave received from a vehicle traveling at a low speed, the terminal device 200 detects the communication wave. An error is likely to be included in the distance D to the vehicle. Therefore, the terminal device 200 may not use the position information of the vehicle that is traveling at a speed higher than the predetermined speed for the self-position measurement by the above-described inter-step communication. Since the traveling speed of the vehicle is included in the provision information transmitted in the inter-vehicle communication as described above, the terminal device 200 determines that the traveling speed included in the received provision information is greater than or equal to a predetermined speed. The location information may not be used.

  For example, when the electric field strength of the communication wave received by the terminal device 200 is extremely low, the distance D from the vehicle detected by the vehicle terminal device 200 is likely to include an error. Therefore, the terminal device 200 may not use the position information of the vehicle that is transmitting the communication wave with the electric field strength smaller than the predetermined value for the self-position measurement by the inter-step communication described above.

  In the above, an example in which WiFi is applied in the wireless communication according to the present invention has been shown. However, in addition to WiFi, the present invention can also be applied to communication of a wireless LAN device that has not been authenticated by WiFi Alliance. it can.

2 Vehicle 100 In-vehicle device (navigation device)
200 Terminal Device 202 WiFi Module 203 Control Unit 205 GPS Positioning Unit 382 WiFi Module 383 Inter-Vehicle Communication Processing Unit 385 Receiver 386 Inter-Vehicle Communication Processing Unit 387 Car I / F Processing Unit

Claims (9)

Information acquisition means for acquiring position information of the plurality of vehicle-mounted devices by performing wireless communication with the plurality of vehicle-mounted devices;
Distance calculating means for calculating distances from the plurality of vehicle-mounted devices based on the electric field strength of radio waves received by the wireless communication;
Based on the positional information of the plurality of in-vehicle devices and the distance to the plurality of in-vehicle devices, measuring means for measuring the self-position,
A terminal device comprising:   The terminal device according to claim 1, wherein the measuring unit measures the self-position based on position information and distances about three or more in-vehicle devices. The information acquisition means acquires the speed of the vehicle on which the in-vehicle device is mounted from the plurality of in-vehicle devices,
The measuring means includes position information acquired from an in-vehicle device mounted on a vehicle that is traveling at a speed equal to or higher than a constant speed and / or an in-vehicle device that transmits a communication wave with an electric field strength smaller than a predetermined value. The terminal device according to claim 1, wherein the terminal device is not used for measuring the position of the terminal device. With GPS positioning means,
4. The terminal device according to claim 1, wherein the measuring unit measures the self-position when the positioning accuracy by the GPS positioning unit is equal to or less than a predetermined allowable accuracy. 5.   The display control means for displaying on the display unit a mark indicating the position of the plurality of vehicle-mounted devices and the self-location on a map based on position information of the plurality of vehicle-mounted devices. The terminal device according to any one of the above. The information acquisition means includes at least one of an attribute of a driver of the vehicle-mounted device, information indicating a behavior of a vehicle equipped with the vehicle-mounted device, and a message input to the vehicle-mounted device from the vehicle-mounted device. Get information,
The terminal device according to claim 5, wherein the display control unit displays the acquired provision information on the display unit. A self-position measuring method executed by a terminal device,
An information acquisition step of acquiring position information of the plurality of vehicle-mounted devices by performing wireless communication with the plurality of vehicle-mounted devices;
A distance calculating step of calculating a distance from the plurality of vehicle-mounted devices based on the electric field strength of the radio wave received by the wireless communication;
Based on the positional information of the plurality of on-vehicle devices and the distance from the plurality of on-vehicle devices, a measuring step for measuring the self-position,
A self-position measuring method comprising: A program executed by a computer installed in a terminal device,
Information acquisition means for acquiring position information of the plurality of vehicle-mounted devices by performing wireless communication with the plurality of vehicle-mounted devices;
Distance calculating means for calculating a distance from the plurality of in-vehicle devices based on the electric field strength of the radio wave received by the wireless communication;
Measuring means for measuring the self-position based on the positional information of the plurality of in-vehicle devices and the distance from the plurality of in-vehicle devices;
A program for causing the computer to function as:   A storage medium storing the program according to claim 8.