JP2008216231A - Communication system, in-vehicle device, vehicle, and transmitter - Google Patents

Abstract

A communication system, an in-vehicle device, and a transmitter capable of accurately specifying a traveling position of a host vehicle and capable of reaching a predetermined position while accurately obtaining a distance to a predetermined position ahead of the traveling direction of the host vehicle And providing a vehicle.
An in-vehicle device 20 acquires the position of the vehicle in a region R with high accuracy, and calculates a distance to a stop line P with high accuracy. Further, the in-vehicle device 20 is based on the arrival time difference of the signals transmitted from the transmitters 30, 40, 50 and the distance to the transmitters 30, 40, 50, and the period of the signals transmitted by the transmitters 30, 40, 50. Is calculated. Thereafter, the host vehicle continues to travel, and at any travel point, based on the arrival time difference of the signals transmitted from the transmitters 30, 40, 50, the calculated synchronization deviation, and the position information of the transmitters 30, 40, 50, Identify your vehicle position.
[Selection] Figure 1

Description

  The present invention relates to a communication system that can specify the position of a vehicle traveling on a road with high accuracy, an in-vehicle device and a transmitter that constitute the communication system, and a vehicle including the in-vehicle device.

Conventionally, in order to prevent traffic accidents between vehicles in and around the intersection or between a vehicle and a pedestrian, the display information of the light color of the traffic light installed at the intersection is used for vehicles traveling toward the intersection. Whether the vehicle can be safely stopped before the intersection based on the received display information, or the vehicle can safely pass through the intersection. There is a system that determines whether or not the vehicle can be operated and alerts the driver with voice according to the determination result. In addition, a traffic light-linked vehicle speed control device that determines whether or not it is possible to safely pass an intersection based on the display information of the traffic signal received by the in-vehicle device and performs vehicle brake control according to the determination result is provided. It has been proposed (see Patent Document 1).
Japanese Patent No. 2806801

  When the vehicle is safely stopped before the intersection, it is necessary to stop the vehicle surely before the stop line provided near the intersection, and it is necessary to accurately grasp the distance from the vehicle to the stop line. However, in the apparatus of Patent Document 1, since the distance from the vehicle to the stop line cannot be accurately determined even when the vehicle is decelerated automatically, the vehicle is surely stopped before the stop line. This is difficult and may cause problems such as overrun. For this reason, in the conventional technology, there has been an inadequate aspect for preventing the traffic accident at the intersection by surely stopping the vehicle before the stop line.

  On the other hand, the vehicle's gyro sensor, acceleration sensor, GPS (Global Positioning System), etc. are used to detect the vehicle's running position, and the location of the intersection is identified based on the map data. The distance to the position of the stop line before the intersection in front of the vehicle can be calculated. However, in the gyro sensor, detection errors accumulate with time, and errors occur due to vehicle vibration. Further, the acceleration sensor has an error due to temperature characteristics, and the detection accuracy is not sufficient. Furthermore, in position detection by GPS or the like, a sufficient number of radio waves such as GPS cannot often be received due to the influence of buildings or vehicles in urban areas, and the error becomes large, so accurate driving support can be performed. It was difficult.

  The present invention has been made in view of such circumstances, and can accurately determine the traveling position of the host vehicle, and accurately determine the distance to the predetermined position in front of the traveling direction of the host vehicle. It is an object to provide a communication system that can be reached, an in-vehicle device and a transmitter that constitute the communication system, and a vehicle including the in-vehicle device.

  A communication system according to a first aspect of the present invention is a communication system including at least three transmitters that transmit signals of the same period, and an in-vehicle device that receives a signal transmitted by the transmitter, Means for storing the position information of the transmitter; first time difference acquisition means for acquiring a first arrival time difference of each signal transmitted by the transmitter when reaching the first point on the road; Second time difference acquisition means for acquiring a second arrival time difference of each signal transmitted by the transmitter upon arrival at the second point after passing through one point, position information of the transmitter, the first And a specifying means for specifying the vehicle position of the second point based on the information on the point, the first arrival time difference, and the second arrival time difference.

  The communication system according to a second aspect of the present invention is the communication system according to the first aspect, wherein the information on the first point includes position information on the first point, distance information from the first point to each transmitter, and each transmitter. At least of the arrival time difference of each signal from the first point to the first point and the arrival time difference of the signal to the first point when the signals transmitted by the transmitters are synchronized. It is characterized by being one.

  A communication system according to a third aspect of the present invention is a communication system comprising at least three transmitters that transmit signals of the same period, and an in-vehicle device that receives signals transmitted by the transmitter, Means for storing position information of the transmitter, time difference acquisition means for acquiring a difference in arrival time of each signal transmitted by the transmitter, and synchronization deviation of the period of the signal transmitted by the transmitter in a predetermined region on the road. A synchronization deviation calculating means for calculating, and a specifying means for specifying the own vehicle position based on the arrival time difference acquired at the traveling point of the own vehicle, the synchronization deviation calculated by the synchronization deviation calculating means, and the position information of the transmitter. It is characterized by providing.

  A communication system according to a fourth invention is the communication system according to the third invention, wherein the in-vehicle device is a position acquisition means for acquiring the vehicle position in the area, and a distance from the vehicle position acquired by the position acquisition means to each transmitter. First synchronization means for calculating a signal transmitted from the transmitter based on the arrival time difference acquired at the vehicle position and the distance from the vehicle position to each transmitter. It is characterized by calculating the synchronization deviation.

  A communication system according to a fifth aspect of the present invention is the communication system according to the fourth aspect, further comprising: a position information transmitter that transmits information related to a position of the region to the in-vehicle device in the region. The vehicle position is obtained based on the transmitted information on the position of the area.

  In a communication system according to a sixth aspect based on the fifth aspect, the position information transmitter is an optical beacon.

  In a communication system according to a seventh invention, in any one of the fourth to sixth inventions, the in-vehicle device stores means for storing position information of the area and whether or not the own vehicle exists in the area. A determination means for determining, and when the determination means determines that the host vehicle is in the area, the position acquisition means determines the position information of the area and the transmitter and the arrival time difference acquired by the time difference acquisition means. Based on this, the vehicle position is acquired.

  A communication system according to an eighth aspect of the present invention is the communication system according to the seventh aspect, further comprising an optical beacon that transmits predetermined information to the in-vehicle device, wherein the in-vehicle device includes a reception unit that receives the information, and the determination unit includes When the predetermined information is received from the optical beacon, the vehicle is determined to be present in the area.

  In a communication system according to a ninth aspect, in any one of the fourth to eighth aspects, the position acquisition means is configured to acquire a position relative to a predetermined first point in the area, Road shape information acquisition means for acquiring road shape information related to the road shape between one point and a predetermined second point downstream of the region in the vehicle traveling direction, and the road acquired by the road shape information acquisition means And a second calculating unit that calculates a distance from the vehicle position to the second point based on the shape information and the position acquired by the position acquiring unit.

  The communication system according to a tenth aspect of the present invention is the communication system according to the ninth aspect, wherein the road shape information includes a distance, a gradient, and a gradient for each section obtained by dividing the road between the first point and the second point into one or a plurality of sections. It includes at least one of curvatures.

  The communication system according to an eleventh aspect of the present invention is the communication system according to the ninth aspect or the tenth aspect, wherein at least one of the transmitter and the optical beacon includes transmission means for transmitting the road shape information to an in-vehicle device. The acquisition means is configured to acquire the road shape information.

  A communication system according to a twelfth aspect of the present invention is the communication system according to any one of the first to eleventh aspects, wherein the in-vehicle device includes means for storing height information of a mounting position, and the specifying means is based on the height information. And the vehicle position is specified.

  A communication system according to a thirteenth aspect of the present invention is the communication system according to any one of the first to twelfth aspects of the present invention, wherein the transmitter includes modulation means for modulating a signal and transmits a signal modulated by the modulation means. And the vehicle-mounted device includes a demodulating unit that demodulates the received signal, and the time difference obtaining unit is configured to obtain the arrival time difference of each signal based on the signal demodulated by the demodulating unit. It is characterized by.

  A communication system according to a fourteenth aspect of the present invention is the communication system according to any one of the first to twelfth aspects of the present invention, wherein the transmitter includes an assigning unit that assigns the signal to a carrier wave of an orthogonal frequency multiplexing system, and the signal is assigned by the assigning unit. The vehicle-mounted device includes a carrier wave receiving unit that receives the carrier wave, and the time difference acquisition unit acquires a time difference of arrival of each signal based on the received carrier wave. It is configured.

  A communication system according to a fifteenth aspect of the present invention is the communication system according to the thirteenth or fourteenth aspect, wherein the transmitter is configured to transmit signals having rising edges at predetermined intervals, and the time difference acquisition means It is configured to acquire the arrival time difference of each signal based on the rising point of the signal.

  A communication system according to a sixteenth aspect of the present invention is the communication system according to any one of the first to twelfth aspects, wherein the transmitter is configured to transmit a signal having an alternating waveform, and the time difference acquisition means receives each signal received. The arrival time difference of each signal is acquired on the basis of the phase difference.

  A communication system according to a seventeenth aspect of the present invention is the communication system according to the sixteenth aspect, wherein the transmitter includes modulation means for modulating a signal, and is configured to transmit a signal modulated by the modulation means. A demodulating means for demodulating the received signal, wherein the time difference acquiring means is configured to acquire the arrival time difference of each signal based on the phase difference of each signal demodulated by the demodulating means; To do.

  A communication system according to an eighteenth aspect of the present invention is the communication system according to any one of the first to twelfth aspects, wherein the transmitter generates a reference period signal having a predetermined period, and a reference period signal generated by the generation means. And determining means for determining the period of the signal.

  In a communication system according to a nineteenth aspect based on the eighteenth aspect, one transmitter is configured to transmit a signal to another transmitter wirelessly or by wire, and the other transmitter receives the received signal. And adjusting means for adjusting the period of the reference periodic signal generated by the generating means, and the determining means determines the period of the signal based on the reference periodic signal whose period is adjusted by the adjusting means. It is configured as described above.

  A communication system according to a twentieth aspect of the present invention is the communication system according to the eighteenth aspect, further comprising a period adjustment transmitter that transmits a period adjustment signal having a predetermined period, wherein the transmitter receives the period adjustment signal transmitted by the period adjustment transmitter. Receiving means, and adjusting means for adjusting the period of the reference periodic signal generated by the generating means based on the received period adjusting signal, and the determining means is a reference periodic signal whose period is adjusted by the adjusting means Based on the above, the period of the signal is determined.

  The communication system according to a twenty-first aspect of the present invention is the communication system according to any one of the first to twelfth aspects, wherein the transmitter is configured to receive a signal transmitted from a GNSS satellite, and to set a signal cycle based on the received signal. Determining means for determining.

  A communication system according to a twenty-second aspect of the present invention is the communication system according to any one of the first to twenty-first aspects, wherein at least one of a traveling direction and a traveling speed of the own vehicle based on the own vehicle position specified by the specifying means at a predetermined time interval. It is characterized by comprising a running value calculation means for calculating one.

  An in-vehicle device according to a twenty-third invention is an in-vehicle device that receives signals of the same period transmitted from at least three transmission points, and means for storing position information of the transmission point, and a first point on the road A first time difference acquisition means for acquiring a first arrival time difference of each transmitted signal at the time of arrival, and each of the transmitted signals upon arrival at the second point after passing through the first point Based on second time difference acquisition means for acquiring a second arrival time difference, position information of the transmission point, information on the first point, the first arrival time difference and the second arrival time difference, the second And specifying means for specifying the position of the vehicle at this point.

  In the on-vehicle device according to a twenty-fourth aspect of the invention, in the twenty-third aspect, the information on the first point includes position information on the first point, distance information from the first point to each transmission point, and each transmission point. Information on the required time of arrival of each signal from the first point to the first point and at least one difference in arrival times of the signals to the first point when the signals are synchronized with each other. Features.

  An in-vehicle device according to a twenty-fifth aspect of the present invention is an in-vehicle device that receives signals of the same period transmitted from at least three transmission points, means for storing position information of the transmission points, and arrival of each transmitted signal Time difference acquisition means for acquiring a time difference, synchronization deviation calculation means for calculating a synchronization deviation of the cycle of the transmitted signal in a predetermined area on the road, arrival time difference obtained at the traveling point of the own vehicle, and the synchronization deviation calculation means And a specifying means for specifying the position of the vehicle based on the synchronization deviation calculated in step 1 and the position information of the transmission point.

  A vehicle according to a twenty-sixth aspect of the invention includes the on-vehicle device according to any of the twenty-third to twenty-fifth aspects of the invention.

  A transmitter according to a twenty-seventh aspect of the present invention is a transmitter for transmitting signals having the same period, a generating means for generating a reference period signal having a predetermined period, and a receiving means for receiving a signal transmitted by another transmitter And adjusting means for adjusting the period of the reference periodic signal generated by the generating means based on the signal received by the receiving means, and the period of the signal based on the reference periodic signal whose period is adjusted by the adjusting means And determining means for determining.

  In the first invention and the 23rd invention, the vehicle-mounted device mounted on the vehicle traveling on the road transmits a signal having the same cycle when reaching the first point (for example, point A) on the road. A first arrival time difference of each signal transmitted by at least three transmitters is obtained. The first point on the road is, for example, a communication point (communication point) between a roadside device such as an optical beacon, a radio beacon, a magnetic nail, DSRC (Dedicated Short Range Communication) and a vehicle. Can do. When the host vehicle further travels and reaches a second point (for example, point B) after passing through the first point, the in-vehicle device acquires a second arrival time difference between the signals transmitted by the transmitters. . The in-vehicle device determines the second point based on the position information of each transmitter, information on the first point (for example, position information on the first point), the first arrival time difference, and the second arrival time difference. Identify your vehicle position.

  Conventionally, hyperbolic navigation such as Loran method or Omega method that detects the phase difference or arrival time difference of radio waves from a plurality of transmitters is known, but the position of the vehicle traveling on the road is, for example, In order to detect with accuracy of 1 m or less, it is necessary to synchronize the radio waves to be transmitted with very high accuracy. On the other hand, according to the present invention, even if signals transmitted by all transmitters are not synchronized with each other, the position of the vehicle can be specified with high accuracy, particularly for vehicles traveling on the road. The position can be tracked with high accuracy.

  In the second invention and the 24th invention, the information of the first point includes the position information of the first point, the distance information from the first point to each transmitter, and the first point from each transmitter. And at least one of the arrival time differences of the signals to the first point when the signals transmitted by the transmitters are synchronized with each other. Thereby, the freedom degree for specifying the positional relationship between a 1st point and each transmitter can be improved.

  In the third invention, the 25th invention and the 26th invention, the in-vehicle device mounted on the vehicle traveling on the road has at least three transmitters for transmitting signals of the same period in a predetermined region on the road. The synchronization deviation of the cycle of the signal to be transmitted is calculated. The predetermined area on the road may be, for example, a communication area between the roadside device and the vehicle such as an optical beacon, a radio wave beacon, a magnetic nail, and a DSRC (Dedicated Short Range Communication). The synchronization deviation of the cycle of the signal transmitted by each transmitter can be calculated based on, for example, the position of the own vehicle, the arrival time difference of each signal, and the distance from the position of the own vehicle to each transmitter. When the vehicle further travels, the in-vehicle device determines the vehicle position based on the synchronization deviation calculated in the predetermined area, the arrival time difference of each signal acquired at the traveling point of the vehicle, and the position information of each transmitter. Identify.

  Conventionally, hyperbolic navigation such as Loran method or Omega method that detects the phase difference or arrival time difference of radio waves from a plurality of transmitters is known, but the position of the vehicle traveling on the road is, for example, In order to detect with accuracy of 1 m or less, it is necessary to synchronize the radio waves to be transmitted with very high accuracy. On the other hand, according to the present invention, even if signals transmitted by all transmitters are not synchronized with each other, the position of the vehicle can be specified with high accuracy, particularly for vehicles traveling on the road. The position can be tracked with high accuracy.

  In the fourth invention, the in-vehicle device acquires the vehicle position in a predetermined area on the road. For example, the vehicle position within a predetermined area can be acquired at the time of communication with an optical beacon, a radio beacon, a magnetic nail, a DSRC, or the like. The in-vehicle device calculates the distance from the acquired own vehicle position to each transmitter, and calculates the synchronization deviation of the signal period transmitted by the transmitter based on the calculated distance and the arrival time difference acquired at the own vehicle position. For example, the distance from the own vehicle position acquired within a predetermined area to the first transmitter is La1, the distance from the own vehicle position to the second transmitter is La2, and the first transmitter and the second transmitter are out of synchronization. Is expressed as ta12−Δt12 = (La1−La2) / α, where Δt12 is the arrival time difference between the signals from the first transmitter and the second transmitter and ta12 is the propagation speed of the radio wave. Similar equations are established for other transmitters, and the synchronization shift can be calculated based on these equations. As a result, even if signals transmitted from all transmitters are not synchronized with each other, the position of the vehicle can be specified with high accuracy.

  In the fifth invention, the position information transmitter transmits information related to the position of the area to the in-vehicle apparatus within a predetermined area on the road. The in-vehicle device receives information related to the position of the region, and identifies the vehicle position based on the received information. For example, when the communication area between the position information transmitter and the in-vehicle device can be limited so that the error regarding the position is sufficiently small, the predetermined area on the road can be made a sufficiently narrow range, Can identify the position of the vehicle at the time of receiving the information on the position of the area transmitted by the position information transmitter.

  In the sixth invention, the position information transmitter is an optical beacon. Thereby, the position of onboard equipment can be specified only by communication (communication) with an optical beacon.

  In the seventh invention, it is determined whether or not the own vehicle is present in a predetermined area on the road by an in-vehicle device mounted on a vehicle traveling on the road. For example, when the in-vehicle device determines that the vehicle is in a predetermined area by communicating with an optical beacon, a radio beacon, a magnetic nail, a DSRC, etc., the in-vehicle device receives and receives signals transmitted by two transmitters. Obtain the arrival time difference of each signal. In this case, it is preferable that the transmitted signals are synchronized with each other. The in-vehicle device obtains a distance difference between the distance between the own vehicle and one transmitter and the distance between the own vehicle and the other transmitter based on the acquired arrival time difference. In this case, the own vehicle exists on a hyperbola where the position of the two transmitters is the focal point and the distance difference is constant. The in-vehicle device specifies the position of the hyperbola based on the position information of the transmitter stored in advance, and further acquires the position on the hyperbola in the predetermined region as the position of the own vehicle based on the position information of the predetermined region. . Thereby, the traveling position of the own vehicle can be acquired with high accuracy. The position information may be acquired and stored from, for example, a map database or may be received from a roadside device and stored.

  In the eighth invention, when the in-vehicle device receives the predetermined information from the optical beacon, the in-vehicle device determines that the host vehicle is in the predetermined region. For example, when the in-vehicle device receives downlink information transmitted from the projector / receiver of the optical beacon, the in-vehicle device transmits uplink information including the vehicle ID of the own vehicle to the projector / receiver. When the optical beacon receives uplink information from the in-vehicle device, the optical beacon transmits predetermined downlink information including the lane notification information storing the vehicle ID included in the received uplink information to the in-vehicle device. When the predetermined downlink information is received, it can be determined that the vehicle is present in a predetermined area (in the communication area of the optical beacon). In addition, since the lane notification information included in the predetermined downlink information is configured in a format in which the lane number is associated with the vehicle ID of the own vehicle, the in-vehicle device automatically identifies the associated lane number. It can be recognized as a driving lane of a car. That is, by using an optical beacon, a predetermined area can be limited to a narrow range of almost one lane on the road, and the position of the own vehicle can be specified with higher accuracy.

  In the ninth invention, position information of a predetermined first point in a predetermined region is stored, and the in-vehicle device sets the position of the own vehicle to a position relative to the first point (for example, a distance from the first point). L2). As a 1st point, it can be set as the point (upstream end) of the upstream of the vehicle advancing direction of a predetermined | prescribed area | region, for example. The in-vehicle device is road shape information (for example, distance L1) regarding the road shape between the first point and a predetermined second point (for example, a stop line before the intersection) that is downstream of the region in the traveling direction of the vehicle. To get. The vehicle-mounted device calculates a distance L3 (L3 = L1-L2) to the second point based on the acquired road shape information (for example, distance L1) and the specified position (distance L2 from the first point). After the distance L3 to the predetermined second point is calculated, when the host vehicle travels toward the second point, the position of the host vehicle can be identified one by one according to the traveling of the host vehicle. It is possible to approach the second point while accurately grasping the distance to the point. That is, it is possible to reach the predetermined position while accurately obtaining the distance to the predetermined position ahead of the traveling direction of the host vehicle.

  In the tenth invention, the road shape information includes at least one of a distance, a gradient, and a curvature for each section obtained by dividing the road between the first point and the second point into one or a plurality of sections. . Thereby, regardless of the road shape between the first point and the second point, the distance between the first point and the second point can be acquired.

  In the eleventh aspect, at least one of each transmitter and optical beacon transmits road shape information to the in-vehicle device. As a result, it is not necessary to store road shape information in advance in the vehicle-mounted device, and for example, road shape information necessary to calculate the distance from the vehicle to the front stop line every time it travels before the required intersection. Can be obtained.

  In the twelfth invention, the in-vehicle device stores the height information of the mounting position when mounted on the vehicle, and specifies the own vehicle position based on the stored height information. When specifying the vehicle position based on the distance to each transmitter calculated at the travel point of the vehicle and the position information of each transmitter, the height of the vehicle-mounted device is taken into consideration, so that Can be calculated with high accuracy, and the vehicle position can be specified with high accuracy.

  In the thirteenth invention, each transmitter transmits the modulated signal to the in-vehicle device, and the in-vehicle device demodulates the received signal and obtains the arrival time difference between the signals based on the demodulated signal. . For example, a signal having a frequency of about 10 kHz can be modulated with a carrier wave of about several hundred MHz. By using a carrier wave in a required frequency band, signals can be transmitted and received using the required frequency band of radio waves.

  In the fourteenth invention, each transmitter assigns a signal to a carrier wave of an orthogonal frequency multiplexing scheme, and transmits the carrier wave to which the signal is assigned. For example, the signal to be transmitted is subjected to inverse Fourier transform and converted to at least one subcarrier (carrier wave) having a different frequency, and the converted signal is DA-converted and transmitted from the transmitter to the vehicle-mounted device. The vehicle-mounted device performs AD conversion on the transmitted carrier wave, and obtains the arrival time difference between the signals by pattern matching between the converted signals. By using the orthogonal frequency multiplexing method, it is possible to improve frequency band utilization efficiency while reducing interference with communication in other bands.

  In the fifteenth aspect, each transmitter transmits a signal having a rising edge at a predetermined interval T1. The predetermined interval T1 is, for example, longer than the total value of the maximum time T2 required until the signal transmitted from the transmitter is received by the in-vehicle device and the time T3 when the delayed wave due to multipath affects the direct wave. To do. The in-vehicle device acquires the arrival time difference based on the time difference at the rising point of each signal transmitted by each transmitter. Thereby, the rising portion of the signal is not affected by the multipath, and the arrival time difference can be obtained with high accuracy.

  In the sixteenth aspect, each transmitter transmits a signal having an alternating waveform (for example, a sine waveform), and the vehicle-mounted device acquires the arrival time difference between the signals based on the phase difference of the received signals. For example, a sinusoidal signal can be transmitted from each transmitter, and the phase difference between the signals received by the vehicle-mounted device can be detected by the phase detector, and the arrival time difference can be obtained with a simple configuration.

  In the seventeenth invention, each transmitter modulates (for example, frequency modulation) a carrier wave (for example, frequency is several hundred MHz) with a sinusoidal signal (for example, frequency is 10 kHz), and the modulated signal is transmitted. Send. The in-vehicle device demodulates the received carrier wave, extracts the original signal, and acquires the arrival time difference based on the phase difference of each signal. The phase difference of each signal can be detected by the phase detector, and the arrival time difference can be acquired with a simple configuration.

  In the eighteenth aspect, each transmitter generates a reference period signal (for example, a reference clock signal from a crystal oscillator) having a predetermined period, and determines the period of the signal based on the generated reference period signal. Since the signal transmitted by each transmitter is determined based on the reference periodic signal, the transmitters can transmit signals having the same period to each other.

  In the nineteenth and twenty-seventh aspects, one transmitter transmits a signal to another transmitter wirelessly or by wire. The other transmitter adjusts the period (frequency) of the reference periodic signal based on the received signal, and determines the period of the signal based on the reference periodic signal whose period has been adjusted. Thereby, even if the period of the reference periodic signal changes from the initial value for some reason (for example, secular change), depending on the period of the signal transmitted by one transmitter, The period of the reference period signal is adjusted, and the other transmitter can transmit a signal having the same period as the period of one signal. Thereby, the period of the signal transmitted by each transmitter can be made the same.

  In the twentieth invention, the cycle adjustment transmitter transmits a cycle adjustment signal having a predetermined cycle (frequency) to each transmitter. Each transmitter receives the period adjustment signal, and adjusts the period (frequency) of the reference period signal based on the received period adjustment signal. Each transmitter determines the period of the signal based on the adjusted reference period signal. Thereby, the period of the signal transmitted by each transmitter can be made the same.

  In the twenty-first invention, each transmitter receives a signal (for example, a signal having a reference oscillation frequency of about 10 MHz) transmitted by a GNSS (Global Navigation Satellite System) satellite, and based on the received signal, Determine the period. Thereby, the period of the signal transmitted by each transmitter can be made the same.

  In the twenty-second aspect, the own vehicle position is specified at predetermined time intervals, and the traveling direction and the traveling speed of the own vehicle are calculated based on the elapsed time and the specified own vehicle position. Thereby, the traveling vector and speed of the own vehicle can be accurately obtained, and the traveling tracking of the own vehicle can also be realized with high accuracy.

  In the present invention, the traveling position of the host vehicle can be specified with high accuracy, and the vehicle can reach the predetermined position while accurately determining the distance to the predetermined position in front of the traveling direction of the host vehicle.

Embodiment 1
Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments. FIG. 1 is a schematic diagram showing an outline of a communication system according to the present invention. The communication system according to the present invention can be realized in particular as a road-to-vehicle communication system, and is installed at a predetermined position near an optical beacon 10, an in-vehicle device 20 mounted on a vehicle, and a road, and transmits a signal having the same period. Transmitters 30, 40, 50, etc. are provided.

  The optical beacon 10 is installed so as to be communicable with the in-vehicle device 20 in a predetermined region R on the road through the communication unit 11 having a projector / receiver. A stop line P is provided on the downstream side of the region R in the vehicle traveling direction.

  The communication system according to the present invention, when it is determined by the in-vehicle device 20 that the vehicle is in the region R in which communication with the optical beacon 10 is possible, based on the arrival time difference between the signals transmitted from the transmitters 30 and 40. The positional relationship with the car transmitters 30 and 40, that is, the position of the vehicle in the region R (for example, point A) is obtained with high accuracy, and the position (distance) to the stop line P is calculated with high accuracy. To do. In addition, the in-vehicle device 20 acquires the transmitter position based on the arrival time difference between the signals transmitted from the transmitters 30, 40, and 50 and the distance to the transmitters 30, 40, and 50 when the vehicle position is acquired. The synchronization deviation of the period of the signal transmitted by 40 and 50 is calculated. Thereafter, the vehicle continues to travel, and at any travel point (for example, point B), the arrival time difference of the signals transmitted from the transmitters 30, 40, 50, the synchronization shift calculated at the point A, and the transmitter 30 Based on the position information of 40, 50, the vehicle position (the position of the point B) is specified. Further, when the host vehicle travels, the in-vehicle device 20 repeatedly specifies the position of the host vehicle in the same manner. In FIG. 1, only one lane is shown on the road, but the number of lanes on the road is not limited to one lane. The present invention can also be applied to roads having lanes. This will be described in detail below.

  FIG. 2 is a block diagram showing the configuration of the communication system according to the present invention. The optical beacon 10 includes a projector / receiver, a communication unit 11 having a communication function with the vehicle-mounted device 20, a control unit 12 that controls the operation of the optical beacon 10, a terminal communication unit 13 having a communication function with the central device 70, A storage unit 14 that stores position information related to the region R on the road that can communicate with the vehicle-mounted device 20 and position information related to the transmitters 30, 40, and 50 is provided. Various types of information stored in the storage unit 14 of the optical beacon 10 can be received from the central device 70. Various information stored in the storage unit 14 can also be stored in the storage unit 14 in advance when the optical beacon 10 is installed.

  The transmitter 30 includes a communication unit 31, a control unit 32, and the like. For example, the communication unit 31 transmits radio waves in the frequency band of the VHF / UHF band to the in-vehicle device 20. The communication unit 31 includes a crystal oscillator that generates a reference clock signal, a carrier wave generation circuit, a modulation circuit, and the like (not shown), and outputs a predetermined signal (for example, a rectangular wave signal having a frequency of about 10 kHz) based on the reference clock signal. Generate. The communication unit 31 performs frequency modulation on a carrier wave (for example, a frequency of about 100 MHz, about 200 MHz, or about 700 MHz) based on the generated signal under the control of the control unit 32, and after modulation through an antenna (not shown) The carrier wave is transmitted. The frequency band used by the transmitter 30 is an example, and is not limited to the VHF / UHF band, and may be another frequency band. For example, a 5.8 GHz band allocated exclusively for automobiles may be used, and a frequency band used for a mobile phone, a PHS, or the like may be used.

  Further, the transmitter 40 includes a communication unit 41, a control unit 42, and the like, and a signal having the same cycle (frequency) as the signal transmitted by the transmitter 30 (for example, a rectangular wave signal having a frequency of about 10 kHz) is transmitted to the in-vehicle device 20. Send to. The configuration of the transmitter 40 is the same as the configuration of the transmitter 30. The signals transmitted by the transmitters 30 and 40 do not necessarily need to be synchronized (in a state in which the rising times of the rectangular wave signals coincide), but are synchronized in order to obtain the vehicle position with high accuracy. Is preferred.

  The transmitter 50 includes a communication unit 51, a control unit 52, and the like, and transmits a signal having the same cycle (frequency) as a signal (for example, a rectangular wave signal having a frequency of about 10 kHz) transmitted by the transmitters 30 and 40. 20 is transmitted. The configuration of the transmitter 50 is the same as the configuration of the transmitters 30 and 40. Note that the signal transmitted by the transmitter 50 does not need to be synchronized with the signal transmitted by the transmitters 30 and 40.

  The in-vehicle device 20 operates the first communication unit 21 having a communication function with the optical beacon 10 using the infrared rays, the second communication unit 22 having a communication function with the transmitters 30, 40, and 50, and the operations of the in-vehicle device 20. A control unit 23 for controlling, a storage unit 24, a display unit 25, an operation unit 26, and the like are provided. The in-vehicle device 20 can also include a GPS (Global Positioning System) reception function, a map database (none of which is shown), and the like.

  The first communication unit 21 receives downlink information transmitted from the optical beacon 10 and transmits uplink information to the optical beacon 10.

  FIG. 3 is an explanatory diagram for explaining bidirectional communication between the optical beacon 10 and the in-vehicle device 20. A region R on the road indicates a region where the in-vehicle device 20 can communicate with the optical beacon 10. As shown in FIG. 3, the region R is divided into a region R1 on the upstream side in the traveling direction of the host vehicle C and a region R2 on the downstream side. Area | region R1 is an area | region which can transmit downlink information with respect to the optical beacon 10 from the vehicle equipment 20 while being able to transmit downlink information with respect to the vehicle equipment 20 from the optical beacon 10. FIG. On the other hand, area | region R2 is an area | region which can transmit downlink information with respect to the vehicle equipment 20 from the optical beacon 10. FIG.

  For example, the optical beacon 10 repeatedly transmits downlink information including lane notification information to the region R on the road at a predetermined downlink period. When the own vehicle C equipped with the in-vehicle device 20 enters the region R, the first communication unit 21 receives the downlink information and outputs the received downlink information to the control unit 23.

  The control unit 23 can determine that the vehicle C exists in the region R by receiving the downlink information through the first communication unit 21. That is, the control unit 23 can determine that the vehicle C exists in the region R at the time ta1 when the first communication unit 21 receives the downlink information.

  When receiving the downlink information, the in-vehicle device 20 repeatedly transmits uplink information including the vehicle ID to the optical beacon 10 through the first communication unit 21 at a predetermined uplink period.

  When the optical beacon 10 receives the uplink information, the optical beacon 10 performs downlink switching, lane notification information, position information about the region R (for example, position information of the most upstream point R0 in the vehicle traveling direction of the region R, The positional relationship between the region R and the transmitters 30, 40, 50, etc.), road shape information including the distance L1 from the point R0 to the stop line P, and position information regarding the transmitters 30, 40, 50, etc. after downlink switching The downlink information is transmitted to the in-vehicle device 20. The position information may be an absolute position represented by latitude and longitude, or may be a relative position from a predetermined reference point.

  The first communication unit 21 receives the downlink information after downlink switching, and outputs the received downlink information to the control unit 23.

  The control unit 23 can also determine that the host vehicle C exists in the region R by receiving the downlink information after downlink switching through the first communication unit 21. That is, the control unit 23 can determine that the host vehicle C exists in the region R at the time ta2 when the first communication unit 21 receives the downlink information after downlink switching. Further, since the lane notification information included in the downlink information after the downlink switching is configured in a format in which the lane number is associated with the vehicle ID of the own vehicle, the control unit 23 is configured to associate the lane with the associated lane. The number can be recognized as the traveling lane of the own vehicle. That is, by using an optical beacon, a predetermined area can be limited to a narrow range of almost one lane on the road, and the position of the own vehicle can be specified with higher accuracy. Note that the time point when it is determined that the host vehicle C exists in the region R may be either the time point ta1 or the time point ta2. In addition, when the communication area between the optical beacon 10 and the vehicle-mounted device 20 can be limited so that the error related to the vehicle position is sufficiently small, the predetermined area R on the road is set to a sufficiently narrow range. The vehicle-mounted device 20 can specify the position of the vehicle as the position of the region R at the time when the information regarding the position of the region R transmitted by the optical beacon 10 is received. Thereby, the position of the vehicle equipment 20 can be specified only by communication (communication) with the optical beacon.

  The second communication unit 22 receives signals transmitted from the transmitters 30, 40, and 50. More specifically, the second communication unit 22 includes a demodulation circuit, receives radio waves transmitted by the transmitters 30, 40, and 50, and demodulates the received radio waves to extract an original signal. The second communication unit 22 calculates the arrival time difference between the signals based on the extracted signals, and outputs the calculated arrival time difference to the control unit 23.

  FIG. 4 is an explanatory diagram illustrating an example of calculating the arrival time difference of signals. FIG. 4 shows signal waveforms transmitted by the transmitters 30 and 40 and signal waveforms received by the in-vehicle device 20 from the transmitters 30 and 40. As shown in FIG. 4, it is assumed that each of the transmitters 30 and 40 transmits signals having the same period in synchronization with each other.

  If the distance from the in-vehicle device 20 to the transmitter 30 is shorter than the distance from the in-vehicle device 20 to the transmitter 40, the signal from the transmitter 30 reaches the in-vehicle device 20 first, and the distance from the transmitter 40 The signal arrives with a delay of ΔT1. The second communication unit 22 calculates the arrival time difference ΔT1 based on each received signal, and outputs the calculated arrival time difference ΔT1 to the control unit 23. Moreover, after calculating the said arrival time difference in multiple times within predetermined time, the method of acquiring these average value or a median value etc. can also be used. According to such a method, the influence by noise etc. can be reduced and the stable arrival time difference can be obtained. The arrival time difference between the signals can be calculated not only at the rising portion of the signal waveform but also at the falling portion.

  When receiving the downlink information after downlink switching through the first communication unit 21, the control unit 23 includes information included in the received downlink information (for example, lane notification information, the most upstream in the vehicle traveling direction in the region R) The position information of the point R0, the distance L1 from the point R0 to the stop line P, the position information regarding the transmitters 30 and 40, and the like) are stored in the storage unit 24.

  When it is determined that the host vehicle exists in the region R (for example, the above-described time point ta2), the control unit 23 acquires the position of the host vehicle based on the arrival time difference ΔT1 acquired through the second communication unit 22. Hereinafter, a method for acquiring the position of the own vehicle will be described.

FIG. 5 is an explanatory diagram showing an example of acquiring the vehicle position based on the arrival time difference of signals. As shown in FIG. 5, a straight line passing through the transmitters 30 and 40 is an x axis, and a straight line passing through the midpoint of the transmitters 30 and 40 and perpendicular to the x axis is a y axis. In the xy coordinate, the x coordinate of the transmitter 30 and the first power of 2 minutes (a ² + b ^2), by integrating the -1 to 1 square of half of the x-coordinate of the transmitter 40 (a ² + b ²⁾ Value. Further, it is assumed that the heights of the vehicle-mounted device 20 and the transmitters 30 and 40 (more specifically, the heights of the respective antennas) match (for example, 50 cm, 1 m, 1 .5m). In this case, the position where the distance difference between the distance to the transmitter 30 and the distance to the transmitter 40 is constant can be expressed by Expression (1). This is a hyperbola that focuses on the position of the transmitters 30, 40.

  That is, as shown in FIG. 5, for example, when the arrival time difference is ΔT1, based on ΔT1, the distance from the vehicle position to the transmitter 30 and the distance from the vehicle position to the transmitter 40 are The distance difference can be calculated, and the position where the hyperbola indicated by ΔT1 in the figure overlaps the region R on the road can be acquired as the position of the host vehicle. In addition, when specifying a hyperbola, the height from the road surface of the vehicle equipment 20 can be determined in advance, such as 50 cm, 1 m, and 1.5 m, for example. Or the installation height information of the vehicle equipment 20 is memorize | stored in the memory | storage part 24, and a hyperbola can be specified using the memorize | stored height.

  Next, description will be made using specific numerical examples. Assume that the transmitters 30 and 40 are installed 20 m apart. If the signal from the transmitter 30 reaches 20 nanoseconds earlier than the signal from the transmitter 40 in the in-vehicle device 20, the arrival time difference is 20 nanoseconds. If the propagation speed of the signal is the speed of light, the distance from the in-vehicle device 20 to the transmitter 30 is 6 m shorter than the distance from the in-vehicle device 20 to the transmitter 40.

  When the position of the own vehicle is (x, y), the position of the own vehicle is on the curve represented by the equation (2). When Expression (2) is calculated, Expression (3) can be derived, and it can be seen that the own vehicle exists at a position where the hyperbola represented by Expression (3) overlaps the region R on the road.

  The display unit 25 is a liquid crystal display panel such as a head-up display, a car navigation system, or a monitoring monitor, and can display various traffic information to the driver. For example, a distance to the intersection or stop line, a warning when the vehicle cannot travel safely at the intersection, and the like are displayed.

  The operation unit 26 includes various operation panels and functions as a user interface between the driver and the in-vehicle device 20. For example, the operation unit 26 receives an operation for starting or stopping the operation of the in-vehicle device 20 by an operation of the driver.

  Next, the operation of the in-vehicle device 20 when acquiring the vehicle position in the region R on the road will be described. FIG. 6 is an explanatory diagram showing the processing contents of the vehicle-mounted device 20 when acquiring the vehicle position. When the own vehicle C travels on the road toward the stop line and enters the region R in which communication with the optical beacon 10 is possible, the in-vehicle device 20 detects the position information of the transmitters 30 and 40 and the upstream end of the region R. Downlink information including position information, positional relationship between the region R and the transmitters 30 and 40, road shape information including the distance L1 from the upstream end (first point) to the stop line (second point) of the region R, etc. Obtained from the optical beacon 10 and temporarily stored. The in-vehicle device 20 determines that the host vehicle C exists in the region R at the time point ta2 when the downlink information is acquired.

  When it is determined that the host vehicle C exists in the region R, the in-vehicle device 20 determines the arrival time difference ΔT1 between the signals transmitted from the transmitters 30 and 40, the height from the road surface of the in-vehicle device 20, and the transmitters 30 and 40. Based on the positional information, the positional relationship between the region R and the transmitters 30 and 40, etc., the hyperbola ΔT1 where the vehicle C exists is specified, and the position where the hyperbola ΔT1 and the region R overlap is determined as the position of the vehicle C (for example, , Point A). Note that the position of the hyperbola ΔT1 in the figure is an example, and the present invention is not limited to this.

  Even when the distance between the hyperbolic line segments that overlap the region R is long, the position information of the region R (for example, the position information of each of the four corners of the region R, the road traveling direction and the straight line formed by the transmitters 30 and 40) For example, the midpoint of the line segment that overlaps the region R in the hyperbola can be set as the position of the vehicle C based on the angle. If the transmitter 30 and 40 are arranged by adjusting the angle between the road traveling direction and the straight line formed by the transmitters 30 and 40, and the angle between the hyperbola and the road traveling direction is as orthogonal as possible, The position of the car C can be acquired with higher accuracy.

  The in-vehicle device 20 calculates a distance L2 from the upstream end of the region R to the own vehicle C based on the acquired position of the own vehicle C (point A), the position of the upstream end of the region R, and the like. Moreover, the vehicle equipment 20 calculates the distance L3 (L3 = L1-L2) to the stop line of the own vehicle C based on the calculated distance L2 and the stored distance L1. Thereby, the distance to the position of the own vehicle C and the predetermined position (for example, stop line) ahead of the traveling direction of the own vehicle C can be obtained with high accuracy.

  Next, after acquiring the vehicle position in a predetermined region R on the road, if the vehicle continues to travel toward a predetermined position (stop line) ahead of the traveling direction from the acquired vehicle position, A method for specifying the travel position will be described.

  FIG. 7 is an explanatory view showing an example of specifying the traveling position of the own vehicle, and FIGS. 8 and 9 are flowcharts showing a processing procedure for specifying the traveling position of the own vehicle. As shown in FIG. 7, the in-vehicle device 20 acquires the vehicle position (referred to as point A) in a predetermined region R on the road, and then the vehicle moves toward a predetermined position (stop line P) ahead in the traveling direction. The vehicle continues to travel and the position of the vehicle is specified at the travel point B. The coordinates of the installation position of the transmitter 30 are (X1, Y1, Z1), the coordinates of the installation position of the transmitter 40 are (X2, Y2, Z2), and the coordinates of the installation position of the transmitter 50 are (X3, Y3, Z3). Hereinafter, a description will be given with reference to FIGS.

  Initially, the control unit 23 determines whether or not the own vehicle exists in a predetermined region R on the road (S11). If the vehicle does not exist in the region R (NO in S11), the process of step S11 is continued. The vehicle waits until the vehicle exists in the region R. When it determines with the own vehicle existing in the area | region R (it is YES at S11), the control part 23 acquires the own vehicle position (S12). Let the acquired own vehicle position be point A. The method for determining whether or not the own vehicle exists in the region R and the method for acquiring the own vehicle position are as described in FIG.

  The control unit 23 calculates the distance from the point A from which the vehicle position is acquired to each transmitter 30, 40, 50 (S13). As shown in FIG. 7, the coordinates of the vehicle-mounted device 20 at the point A are (Xa, Ya, Za), and the distances from the vehicle position to the transmitters 30, 40, 50 are La1, La2, La3, respectively. .

  The control part 23 acquires the arrival time difference of the signal which each transmitter 30,40,50 transmitted in the point A (S14). In addition, the arrival time difference of each signal transmitted by the transmitter 30 and the transmitter 40 is ta12, the arrival time difference of each signal transmitted by the transmitter 40 and the transmitter 50 is ta23, and each signal transmitted by the transmitter 50 and the transmitter 30 is transmitted. The arrival time difference of is assumed to be ta31.

  The control unit 23 calculates the synchronization deviation of the signals transmitted by the transmitters 30, 40, 50 (S15). Δt12 indicates the synchronization deviation of the period of each signal transmitted by the transmitter 30 and the transmitter 40, Δt23 indicates the synchronization deviation of the period of each signal transmitted by the transmitter 40 and the transmitter 50, and the transmitter 50 and the transmitter 30 transmit. When the synchronization deviation of the period of each signal is Δt31, the synchronization deviation can be calculated by calculating Expression (4). Here, α is the propagation speed of radio waves.

  The control unit 23 sets a timer (S16). Thereby, the control part 23 repeats the process which pinpoints the own vehicle position by a predetermined time interval. Thereafter, it is assumed that the host vehicle continues to travel and reaches point B. The control part 23 acquires the arrival time difference of the signal which each transmitter 30,40,50 transmitted in the point B (S17). In addition, the arrival time difference of each signal transmitted by the transmitter 30 and the transmitter 40 is tb12, the arrival time difference of each signal transmitted by the transmitter 40 and the transmitter 50 is tb23, and each signal transmitted by the transmitter 50 and the transmitter 30 is transmitted. Let tb31 be the arrival time difference.

  At the point B, the control unit 23 determines the own vehicle position based on the synchronization deviations Δt12, Δt23, Δt31 calculated at the point A, and the arrival time difference calculated at the point B based on tb12, tb23, tb31, and the height of the vehicle-mounted device 20. Is specified (S18).

  The specification of the own vehicle position can be performed based on any two formulas in formula (5) and formula (6). Here, Lb1, Lb2, and Lb3 are distances from the point B that is the position of the vehicle to the transmitters 30, 40, and 50, respectively, and Xb, Yb, and Zb are the coordinates of the vehicle-mounted device 20 at the point B, respectively. is there. In this case, Zb which is the height of the vehicle-mounted device 20 is known.

  The control unit 23 calculates the traveling direction and speed of the vehicle based on the coordinates of the points A and B, the elapsed time, etc. (S19), and sets the distance L3 to the predetermined position (stop line P) calculated at the point A. Based on this, the distance from the point B to the predetermined position is calculated (S20). Thereby, the traveling vector of the vehicle can be accurately obtained, and the speed can also be accurately obtained from the traveling vector. In addition, if the lane number in which the vehicle travels is known at the point A, the lane number traveling at the point B can be specified by storing the lane width in advance.

  The control unit 23 determines whether or not there is an instruction to end the process (S21). If there is no instruction to end the process (NO in S21), the control unit 23 determines whether or not the timer has elapsed (S22). If so (YES at S22), the processing after step S16 is continued. If the predetermined time has not elapsed (NO in S22), the process of step S22 is continued and waits until the predetermined time elapses. On the other hand, when there is an instruction to end the process (YES in S21), the control unit 23 ends the process.

  Thereby, even if the signals transmitted by all the transmitters 30, 40, 50 are not synchronized with each other, the position of the vehicle can be specified with high accuracy. In particular, the position of the vehicle traveling on the road is determined one by one. It can be tracked with high accuracy.

  In the above-described embodiment, the configuration is such that the synchronization deviation of the signals transmitted by the transmitters 30, 40, and 50 is calculated. However, the position of the vehicle can also be accurately identified without calculating the synchronization deviation. In this case, the position of the vehicle is specified based on the equations obtained by eliminating the synchronization shifts Δt12, Δt23, and Δt31 from the equations (4) and (5). Hereinafter, a method for specifying the position of the vehicle without calculating the synchronization deviation will be described.

  10 and 11 are flowcharts showing a processing procedure for specifying the traveling position of the host vehicle. Also in this case, as shown in FIG. 7, the in-vehicle device 20 acquires the own vehicle position (referred to as point A) in a predetermined region R on the road, and then the predetermined position (a stop line) in which the own vehicle is ahead in the traveling direction. It is assumed that the vehicle continues to travel toward P) and the position of the vehicle is specified at the travel point B. The coordinates of the installation position of the transmitter 30 are (X1, Y1, Z1), the coordinates of the installation position of the transmitter 40 are (X2, Y2, Z2), and the coordinates of the installation position of the transmitter 50 are (X3, Y3, Z3). Hereinafter, a description will be given with reference to FIGS. 10 and 11.

  The control unit 23 determines whether or not the vehicle is in the predetermined region R on the road (S31). If the vehicle is not in the region R (NO in S31), the control unit 23 continues the process of step S31, Wait until the car is in region R. When it determines with the own vehicle existing in the area | region R (it is YES at S31), the control part 23 acquires the information of the position of the point A (1st point) which is an own vehicle position (S32), and each transmitter The position information (for example, the coordinates of the installation position) of 30, 40, 50 is acquired (S33).

  As information on the position of the point A, for example, the coordinates (Xa, Ya, Za) of the in-vehicle device 20, the distances La1, La2, La3 from the point A to the transmitters 30, 40, 50, the transmitters 30, 40, The required time La1 / α, La2 / α, La3 / α of each signal from 50 to point A, and the point A of each signal when the signals transmitted by the transmitters 30, 40, 50 are synchronized with each other. The arrival time difference (La1-La2) / α, (La2-La3) / α, (La3-La1) / α, etc. Here, α is the propagation speed of radio waves. Further, the information on the position of the point A can be acquired from the optical beacon 10.

  The control part 23 acquires the 1st arrival time difference of the signal which each transmitter 30,40,50 transmitted in the point A (S34). The first arrival time difference between the signals transmitted by the transmitter 30 and the transmitter 40 is ta12, the first arrival time difference between the signals transmitted by the transmitter 40 and the transmitter 50 is ta23, the transmitter 50 and the transmitter. The first arrival time difference between the signals transmitted by 30 is ta31.

  The control unit 23 sets a timer (S35). Thereby, the control part 23 repeats the process which pinpoints the own vehicle position by a predetermined time interval. Thereafter, it is assumed that the host vehicle continues to travel and reaches point B (second point). The control part 23 acquires the 2nd arrival time difference of the signal which each transmitter 30,40,50 transmitted in the point B (S36). Note that the second arrival time difference between the signals transmitted by the transmitter 30 and the transmitter 40 is tb12, the second arrival time difference between the signals transmitted by the transmitter 40 and the transmitter 50 is tb23, the transmitter 50, and the transmitter. The second arrival time difference between the signals transmitted by 30 is defined as tb31.

  At the point B, the control unit 23 detects the position information of the point A (for example, distances La1, La2, and La3 from the point A to the transmitters 30, 40, and 50) and the installation positions of the transmitters 30, 40, and 50. Coordinates (X1, Y1, Z1), (X2, Y2, Z2), (X3, Y3, Z3), first arrival time differences ta12, ta23, ta31, second arrival time differences tb12, tb23, tb31, and the vehicle-mounted device Based on the height of 20, the vehicle position is specified (S37).

  The vehicle position can be specified based on the equations (4) and (5) obtained by eliminating the synchronization deviations Δt12, Δt23, and Δt31, and the equation (6). Here, Lb1, Lb2, and Lb3 are distances from the point B that is the position of the vehicle to the transmitters 30, 40, and 50, respectively, and Xb, Yb, and Zb are the coordinates of the vehicle-mounted device 20 at the point B, respectively. is there. In this case, Zb which is the height of the vehicle-mounted device 20 is known.

  The control unit 23 calculates the travel direction and speed of the vehicle based on the coordinates of the points A and B, the elapsed time, etc. (S38), and sets the distance L3 to the predetermined position (stop line P) calculated at the point A. Based on this, the distance from the point B to the predetermined position is calculated (S39). Thereby, the traveling vector of the vehicle can be accurately obtained, and the speed can also be accurately obtained from the traveling vector. In addition, if the lane number in which the vehicle travels is known at the point A, the lane number traveling at the point B can be specified by storing the lane width in advance.

  The control unit 23 determines whether or not there is an instruction to end the process (S40). If there is no instruction to end the process (NO in S40), the control unit 23 determines whether or not the timer has elapsed (S41). If so (YES in S41), the processing after step S35 is continued. If the predetermined time has not elapsed (NO in S41), the process of step S41 is continued and waits until the predetermined time elapses. On the other hand, when there is an instruction to end the process (YES in S40), the control unit 23 ends the process.

  FIG. 12 is an explanatory diagram illustrating an example of synchronization deviation of signals transmitted from the transmitters 30, 40, and 50. As shown in FIG. 12, the signals transmitted by the transmitter 30 and the transmitter 40 cause a synchronization shift of Δt12, and the signals transmitted by the transmitter 40 and the transmitter 50 cause a synchronization shift of Δt23. The signals transmitted by the transmitter 50 and the transmitter 30 are out of synchronization by Δt31. In order to obtain the vehicle position accurately in the predetermined region R, it is preferable that the signals transmitted by the transmitters 30 and 40 are synchronized with each other, but other methods such as a magnetic nail are used in combination. If the vehicle position can be acquired within the allowable limit in the region R by narrowing the region R that is a communicable region by the optical beacon 10 or by synchronizing the signals transmitted by the transmitters 30 and 40 Is not necessarily required.

  FIG. 13 is an explanatory diagram illustrating an example of the arrival time difference between signals transmitted by the transmitters 30, 40, and 50. As shown in FIG. 13A, at the point A, the signals transmitted by the transmitter 30 and the transmitter 40 cause a difference in arrival time by ta12, and the signals transmitted by the transmitter 40 and the transmitter 50 are ta23. Only the arrival time difference is generated, and the signals transmitted by the transmitter 50 and the transmitter 30 have the arrival time difference by ta31. Further, as shown in FIG. 13B, at the point B, the signals transmitted by the transmitter 30 and the transmitter 40 cause arrival time differences by tb12, and the signals transmitted by the transmitter 40 and the transmitter 50 are , Tb23 causes an arrival time difference, and the signals transmitted by the transmitter 50 and the transmitter 30 cause an arrival time difference by tb31. As shown in FIG. 13, the arrival time difference varies depending on the traveling position of the vehicle.

  FIG. 14 is an explanatory diagram illustrating an example of a transmission interval of signals transmitted by the transmitters 30 and 40. As shown in FIG. 14, the transmitters 30 and 40 transmit a rectangular transmission waveform at a predetermined interval T1. The signals transmitted by the transmitters 30 and 40 are combined (superimposed) with the direct wave that directly reaches the vehicle-mounted device 20 and the delayed wave that arrives after being delayed by the direct wave after being reflected by a building or the like existing in the surroundings. It becomes a composite wave. Accordingly, the reception waveform of the signal received by the in-vehicle device 20 is a waveform in which a signal delayed by multipath is superimposed on the transmission waveform, and the time when the delayed wave due to multipath directly affects the wave is, for example, T3 Become. Further, the time when the vehicle-mounted device 20 receives a signal is delayed by, for example, the maximum time T2 from the time when the transmitters 30 and 40 transmit the signal according to the distance between the vehicle-mounted device 20 and the transmitters 30 and 40.

  In this case, by setting the transmission interval T1 of the signals transmitted by the transmitters 30 and 40 to T1> T2 + T3, the rising portion of each signal received by the in-vehicle device 20 is not affected by the multipath, and the accuracy is increased. The arrival time difference can be obtained well. The same applies to the transmission interval of signals transmitted by the transmitters 30 and 50 and the transmission interval of signals transmitted by the transmitters 40 and 50.

  The signals transmitted by the transmitters 30, 40, 50 are generated in synchronization with, for example, a reference clock signal so as to transmit signals having the same period. However, the oscillation frequency of the crystal oscillator that generates the reference clock signal may cause an error due to secular change or the like, and the period (frequency) of the signal transmitted by each transmitter 30, 40, 50 may be shifted. Hereinafter, a method for making the signal periods of the transmitters 30, 40, and 50 the same will be described.

  FIG. 15 is an explanatory diagram showing an example of a method for making the periods of signals transmitted by the transmitters 40 and 50 the same. FIG. 15A shows a case where the signal period is shifted. The period of the signal transmitted by the transmitter 40 is T4, and the period of the signal transmitted by the transmitter 50 is T4 ′ different from T4. Yes. In this case, each transmitter 30, 40, 50 is provided with a phase-locked loop (PLL), and for example, the transmitter 40 transmits a signal to the transmitter 50 wirelessly or by wire. The transmitter 50 adjusts the cycle (frequency) of the reference clock signal based on the received signal, and determines the cycle of the signal based on the reference clock signal whose cycle has been adjusted. As a result, as shown in FIG. 15B, the cycle of the signal transmitted by the transmitter 50 can be corrected from T4 ′ to T4 so as to be the same as the cycle of the signal of the transmitter 30. In addition, the period of the signal between the transmitter 30 and the transmitter 40 or between the transmitter 30 and the transmitter 50 can be adjusted similarly.

  FIG. 16 is an explanatory diagram showing an example of the same synchronization of signals transmitted by the transmitters 40 and 50. The period of the signals transmitted by the transmitters 40 and 50 is the same period means that the intervals at which the transmitters 40 and 50 transmit signals are not different between the transmitters 40 and 50. That is, as shown in FIG. 16A, not only when all transmitters 40 and 50 continue to transmit signals at the same interval (T4), but also as shown in FIG. , The transmission interval of 50 signals varies with time.

  That is, as shown in FIG. 16B, the transmitters 40 and 50 similarly change the transmission interval, and the transmission start timing shift (T5) of the signals of the transmitters 40 and 50 is kept constant. It only has to be drunk. In order to change the transmission interval of the transmitter 50 in conjunction with the transmission interval of the transmitter 40, the transmitter 40 is regarded as a parent device, and the slave unit including the transmitter 50 receives the signal from the transmitter 40. A signal may be transmitted immediately after receiving (or after a predetermined time has elapsed). By doing so, the signal transmission interval of the slave unit can be changed in conjunction with the signal transmission interval of the master unit.

  In addition, the method of making the period of the signal which each transmitter transmits the same is not limited to the example of FIG. 15, and other methods may be used. For example, a transmitter for adjusting the period is installed separately from the transmitters 30, 40, and 50. The cycle adjustment transmitter transmits a cycle adjustment signal having a predetermined cycle to the transmitters 30, 40, and 50. The transmitters 30, 40, and 50 receive the period adjustment signal, adjust the period (frequency) of the reference clock signal based on the period (frequency) of the period adjustment signal, and based on the reference clock signal whose period has been adjusted. Thus, the period of the signal can be determined.

  Further, instead of the period adjusting transmitter, a signal transmitted by a GNSS (Global Navigation Satellite System) satellite including GPS is received, and a signal having a reference oscillation frequency (for example, about 10 MHz) is extracted from the received signal. The period (frequency) of the reference clock signal is adjusted based on the extracted signal of the reference oscillation frequency, and the period of the signal can be determined based on the reference clock signal whose period is adjusted.

  The waveform of the signal transmitted by the transmitter 30, 40, 50 is not limited to a rectangular waveform, and may be a sine waveform. FIG. 17 is an explanatory diagram showing an example of calculating the arrival time difference when a sinusoidal waveform signal is used. FIG. 17 shows signal waveforms transmitted by the transmitters 30 and 50 and signal waveforms received by the vehicle-mounted device 20 from the transmitters 30 and 50. As shown in FIG. 17, each of the transmitters 30 and 50 transmits a signal having the same period.

  In this case, the second communication unit 22 includes a phase detector (not shown), receives signals transmitted from the transmitters 30 and 50, and outputs the received signals to the phase detector. The phase detector detects the phase difference of each signal, and thereby can calculate the arrival time difference ΔT of each signal with a simple configuration.

  In addition, when transmitting the signal of the above sine waveform, it is also possible to modulate and transmit the signal. For example, the transmitters 30, 40, and 50 modulate a carrier wave (for example, a frequency of several hundred MHz) with a sinusoidal signal (for example, a frequency of 10 kHz), and transmit the modulated signal. . The in-vehicle device 20 can demodulate the received carrier wave, extract the original signal, and acquire the arrival time difference based on the phase difference of each signal.

Embodiment 2
In Embodiment 1 described above, three transmitters are used for positioning, but the number of transmitters is not limited to three, and may be a configuration using four or more transmitters.

  FIG. 18 is an explanatory diagram illustrating an example of specifying the traveling position of the host vehicle according to the second embodiment. As shown in FIG. 18, in the second embodiment, the optical beacon 10, the in-vehicle device 20 mounted on the vehicle, and the transmitters 30, 40, 50 that are installed at predetermined positions near the road and transmit signals with the same period. , 60 and the like. The difference from the first embodiment is that a transmitter 60 is provided. The configuration of the transmitter 60 is the same as that of the transmitters 30, 40, and 50, and thus description thereof is omitted. In the following, the method for identifying the vehicle position will be described with reference to FIG.

  As shown in FIG. 18, the in-vehicle device 20 acquires its own vehicle position (referred to as point A) in a predetermined region R on the road, and then the own vehicle moves toward a predetermined position (stop line P) ahead in the traveling direction. The vehicle continues to travel and the position of the vehicle is specified at the travel point B. The coordinates of the installation position of the transmitter 30 are (X1, Y1, Z1), the coordinates of the installation position of the transmitter 40 are (X2, Y2, Z2), and the coordinates of the installation position of the transmitter 50 are (X3, Y3, Z3), and the coordinates of the transmitter 60 installation position are (X4, Y4, Z4).

  The in-vehicle device 20 (the control unit 23) determines whether or not the own vehicle is present in the predetermined region R on the road, and acquires the own vehicle position when it is determined that the own vehicle is present in the region R. . Let the acquired own vehicle position be point A. The method for determining whether or not the own vehicle exists in the region R and the method for acquiring the own vehicle position are as described in FIG.

  The in-vehicle device 20 calculates the distance from the point A from which the vehicle position is acquired to each transmitter 30, 40, 50, 60. As shown in FIG. 18, the coordinates of the vehicle-mounted device 20 at the point A are (Xa, Ya, Za), and the distances from the vehicle position to the transmitters 30, 40, 50, 60 are La1, La2, La3, respectively. , La4.

  The vehicle-mounted device 20 acquires the arrival time difference between the signals transmitted by the transmitters 30, 40, 50 and 60 at the point A. Note that the arrival time difference between the signals transmitted by the transmitter 30 and the transmitter 40 is ta12, the arrival time difference between the signals transmitted by the transmitter 30 and the transmitter 50 is ta13, and each signal transmitted by the transmitter 30 and the transmitter 60 is transmitted. The arrival time difference of is assumed to be ta14.

  The in-vehicle device 20 calculates the synchronization deviation of the signals transmitted by the transmitters 30, 40, 50, and 60. Δt12 indicates the synchronization deviation of the period of each signal transmitted by the transmitter 30 and the transmitter 40, Δt13 indicates the synchronization deviation of the period of each signal transmitted by the transmitter 30 and the transmitter 50, and the transmitter 30 and the transmitter 60 transmit. When the synchronization deviation of the period of each signal is Δt14, the synchronization deviation can be calculated by calculating Expression (7). Here, α is the propagation speed of radio waves.

  It is assumed that the vehicle-mounted device 20 subsequently travels and reaches the point B. The in-vehicle device 20 acquires the arrival time difference between the signals transmitted by the transmitters 30, 40, 50 and 60 at the point B. Note that the arrival time difference between the signals transmitted by the transmitter 30 and the transmitter 40 is tb12, the arrival time difference between the signals transmitted by the transmitter 30 and the transmitter 50 is tb13, and each signal transmitted by the transmitter 30 and the transmitter 60 is transmitted. Let tb14 be the arrival time difference.

  The in-vehicle device 20 identifies the own vehicle position at the point B based on the synchronization deviations Δt12, Δt13, Δt14 calculated at the point A, and the arrival time differences calculated at the point B based on tb12, tb13, tb14. The position of the own vehicle can be specified based on the equations (8) and (9). Here, Lb1, Lb2, Lb3, and Lb4 are distances from the point B that is the position of the vehicle to the transmitters 30, 40, 50, and 60, respectively, and Xb, Yb, and Zb are on-vehicle devices at the point B, respectively. There are 20 coordinates.

  The in-vehicle device 20 calculates the traveling direction and speed of the vehicle based on the coordinates of the points A and B, the elapsed time, and the like, and based on the distance L3 to the predetermined position (stop line P) calculated at the point A, The distance from the point B to the predetermined position is calculated. Thereby, the traveling vector of the vehicle can be accurately obtained, and the speed can also be accurately obtained from the traveling vector. In addition, if the lane number in which the vehicle travels is known at the point A, the lane number traveling at the point B can be specified by storing the lane width in advance.

  Thereby, even if the signals transmitted by all the transmitters 30, 40, 50, 60 are not synchronized with each other, the position of the vehicle can be specified with high accuracy. In particular, the position of the vehicle traveling on the road Can be tracked with high accuracy.

  As described above, in the present invention, once the vehicle position is acquired, the position of the vehicle can be accurately identified when the vehicle continues to travel from that position. The position of the vehicle traveling on the road can be tracked with high accuracy. Further, even if signals transmitted from all transmitters are not synchronized with each other, the position of the vehicle can be specified with high accuracy. In addition, it is possible to reach the predetermined position while accurately obtaining the distance to the predetermined position in front of the traveling direction of the host vehicle.

  Further, in the present invention, signals can be transmitted and received using a required frequency band of radio waves by using a carrier wave of a required frequency band. In addition, the rising portion of the signal is not affected by the multipath, and the arrival time difference can be obtained with high accuracy. Moreover, the arrival time difference of signals can be acquired with a simple configuration. Each transmitter can transmit signals having the same period.

  In the above-described embodiment, the transmitters 30 to 60 modulate and transmit the signal, and the in-vehicle device 20 demodulates and extracts the original signal, and calculates the arrival time difference between the signals. However, the transmitters 30 to 60 allocate signals to carriers having different frequencies in the orthogonal frequency multiplexing scheme, and transmit the carriers to which the signals are allocated. For example, the signal to be transmitted is subjected to inverse Fourier transform to be converted into at least one subcarrier (carrier wave) having a different frequency, and the converted signal is DA-converted and transmitted from the transmitters 30 to 60 to the in-vehicle device 20. The in-vehicle device 20 performs AD conversion on the transmitted carrier wave, and obtains the arrival time difference between the signals by pattern matching between the converted signals. Thereby, the utilization efficiency of a frequency band can be improved, reducing interference with communication in other bands.

  In the above-described embodiment, the position information or the like is transmitted from the optical beacon 10 to the in-vehicle device 20, but is not limited to this, and any one of the transmitters 30 to 60 is located in the in-vehicle device 20. It can also be configured to transmit information or the like. Further, the in-vehicle device 20 may be provided with GPS, map data, and the like, and necessary position information may be stored in advance. In this case, it is not necessary to transmit position information or the like from the optical beacon 10 or the transmitters 30 to 60. In this case, the control unit 23 can determine that the vehicle C exists in the region R at the time ta1 when the first communication unit 21 receives the downlink information.

  As shown in the above-described embodiment, for road shape information, in addition to the method of setting the distance L1 from the upstream end (first point) of the region R to the stop line P (second point), the following It is good as a form. For example, a plurality of nodes (road sections) are set between the upstream end of the region R and the stop line P, the distance from the upstream end of the region R to the node closest to the upstream end, the distance between the nodes, and Each of the distances from the nearest node to the stop line P to the stop line may be stored. The distance between the nodes may be set to be always constant (for example, 20 m), and the gradient or curvature between the nodes may be stored. That is, the road shape information may be in any format as long as the distance from the upstream end (first point) of the region R to the stop line P (second point) can be acquired.

  According to the above-described invention, the position of the traveling vehicle can be specified with high accuracy. Therefore, by using the present invention, for example, display information of a traffic signal ahead is received by an in-vehicle device, and based on the received display information. Therefore, it is determined with high accuracy whether it is possible to stop safely before the intersection, or whether it is possible to safely pass the intersection, and the driver is alerted by voice according to the determination result. be able to. In addition, based on the display information of the traffic lights received by the in-vehicle device, it is possible to determine with high accuracy whether or not it is possible to pass through the intersection safely, and it is possible to perform vehicle brake control according to the determination result. Accidents can be prevented and traffic safety can be improved.

  The disclosed embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic diagram which shows the outline | summary of the communication system which concerns on this invention. It is a block diagram which shows the structure of the communication system which concerns on this invention. It is explanatory drawing explaining the bidirectional | two-way communication between an optical beacon and vehicle equipment. It is explanatory drawing which shows the example of calculation of the arrival time difference of a signal. It is explanatory drawing which shows the example which acquires the own vehicle position based on the arrival time difference of a signal. It is explanatory drawing which shows the processing content of the vehicle equipment in the case of acquiring the own vehicle position. It is explanatory drawing which shows the example which specifies the traveling position of the own vehicle. It is a flowchart which shows the process sequence which pinpoints the driving | running | working position of the own vehicle. It is a flowchart which shows the process sequence which pinpoints the driving | running | working position of the own vehicle. It is a flowchart which shows the process sequence which pinpoints the driving | running | working position of the own vehicle. It is a flowchart which shows the process sequence which pinpoints the driving | running | working position of the own vehicle. It is explanatory drawing which shows the example of the synchronization shift | offset | difference of the signal which each transmitter transmits. It is explanatory drawing which shows the example of the arrival time difference of the signal which each transmitter transmits. It is explanatory drawing which shows the example of the transmission interval of the signal which a transmitter transmits. It is explanatory drawing which shows the example of the method of making the period of the signal which a transmitter transmits the same. It is explanatory drawing which shows the example of the same synchronization of the signal which a transmitter transmits. It is explanatory drawing which shows the example of calculation of the arrival time difference at the time of using the signal of a sine waveform. It is explanatory drawing which shows the example which pinpoints the driving | running | working position of the own vehicle of Embodiment 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical beacon 11 Communication part 12 Control part 13 Terminal communication part 14 Storage part 20 Car-mounted machine 21 1st communication part 22 2nd communication part 23 Control part 24 Storage part 25 Display part 26 Operation part 30, 40, 50, 60 Transmitter 31, 41, 51 Communication unit 32, 42, 52 Control unit

Claims (27)

A communication system comprising at least three transmitters that transmit signals of the same period, and an in-vehicle device that receives signals transmitted by the transmitters,
The in-vehicle device is
Means for storing location information of the transmitter;
First time difference acquisition means for acquiring a first arrival time difference of each signal transmitted by the transmitter when reaching a first point on the road;
Second time difference acquisition means for acquiring a second arrival time difference of each signal transmitted by the transmitter when reaching the second point after passing through the first point;
Specifying means for specifying the vehicle position of the second point based on the position information of the transmitter, information on the first point, the first arrival time difference and the second arrival time difference. A featured communication system. The information of the first point is
Position information of the first point, distance information from the first point to each transmitter, information on time required to reach each signal from each transmitter to the first point, and transmission from each transmitter 2. The communication system according to claim 1, wherein at least one of the arrival time differences of the signals to the first point when the signals to be synchronized with each other is synchronized. A communication system comprising at least three transmitters that transmit signals of the same period, and an in-vehicle device that receives signals transmitted by the transmitters,
The in-vehicle device is
Means for storing location information of the transmitter;
Time difference acquisition means for acquiring the arrival time difference of each signal transmitted by the transmitter;
Synchronization deviation calculating means for calculating the synchronization deviation of the period of the signal transmitted by the transmitter in a predetermined area on the road;
A communication unit comprising: a means for specifying a vehicle position based on a difference in arrival time acquired at a travel point of the vehicle, a synchronization shift calculated by the synchronization shift calculation unit, and position information of the transmitter. . The in-vehicle device is
Position acquisition means for acquiring the vehicle position in the region;
First calculation means for calculating the distance from the vehicle position acquired by the position acquisition means to each transmitter;
The synchronization deviation calculating means includes
The system is configured to calculate a synchronization deviation of a signal transmitted by the transmitter based on an arrival time difference acquired at the own vehicle position and a distance from the own vehicle position to each transmitter. Item 4. The communication system according to Item 3. A position information transmitter for transmitting information on the position of the region to the in-vehicle device in the region;
The position acquisition means includes
The communication system according to claim 4, wherein the vehicle position is acquired based on information on the position of the area transmitted by the position information transmitter. The location information transmitter is
The communication system according to claim 5, wherein the communication system is an optical beacon. The in-vehicle device is
Means for storing position information of the region;
Determination means for determining whether or not the own vehicle exists in the area,
The position acquisition means includes
When the determination means determines that the vehicle is in the area, the vehicle position is acquired based on the position information of the area and the transmitter and the arrival time difference acquired by the time difference acquisition means. The communication system according to any one of claims 4 to 6, characterized in that: An optical beacon that transmits predetermined information to the in-vehicle device,
The in-vehicle device is
Receiving means for receiving the information;
The determination means includes
The communication system according to claim 7, wherein when predetermined information is received from the optical beacon, the vehicle is determined to be present in the area. The position acquisition means includes
Configured to obtain a position relative to a predetermined first point in the region;
Road shape information acquisition means for acquiring road shape information relating to a road shape between the first point and a predetermined second point located downstream of the region in the traveling direction of the vehicle;
And a second calculating unit that calculates a distance from the vehicle position to the second point based on the road shape information acquired by the road shape information acquiring unit and the position acquired by the position acquiring unit. The communication system according to any one of claims 4 to 8.   The road shape information includes at least one of a distance, a gradient, and a curvature for each section obtained by dividing the road between the first point and the second point into one or a plurality of sections. Item 10. The communication system according to Item 9. At least one of the transmitter and the optical beacon includes a transmission unit that transmits the road shape information to an in-vehicle device,
The road shape information acquisition means
The communication system according to claim 9 or 10, wherein the road shape information is acquired. The in-vehicle device is
Means for storing height information of the mounting position;
The specifying means is:
The communication system according to any one of claims 1 to 11, wherein the vehicle position is specified based on the height information. The transmitter is
Comprising modulation means for modulating the signal;
It is configured to transmit a signal modulated by the modulation means,
The in-vehicle device is
A demodulating means for demodulating the received signal;
The time difference acquisition means includes
The communication system according to any one of claims 1 to 12, wherein an arrival time difference of each signal is acquired based on a signal demodulated by the demodulation means. The transmitter is
Allocating means for allocating signals to orthogonal frequency multiplexing carrier waves;
It is configured to transmit a carrier wave to which a signal is assigned by the assigning means,
The in-vehicle device is
A carrier receiving means for receiving the carrier;
The time difference acquisition means includes
The communication system according to any one of claims 1 to 12, wherein an arrival time difference of each signal is acquired based on a received carrier wave. The transmitter is
It is configured to transmit a signal having a rising edge at a predetermined interval,
The time difference acquisition means includes
The communication system according to claim 13 or 14, wherein a difference in arrival time of each signal is acquired based on a rising time of each received signal. The transmitter is
It is configured to transmit an alternating waveform signal,
The time difference acquisition means includes
The communication system according to any one of claims 1 to 12, wherein an arrival time difference of each signal is acquired based on a phase difference of each received signal. The transmitter is
Comprising modulation means for modulating the signal;
It is configured to transmit a signal modulated by the modulation means,
The in-vehicle device is
A demodulating means for demodulating the received signal;
The time difference acquisition means includes
17. The communication system according to claim 16, wherein an arrival time difference of each signal is acquired based on a phase difference of each signal demodulated by the demodulation means. The transmitter is
Generating means for generating a reference period signal of a predetermined period;
The communication system according to claim 1, further comprising: a determination unit that determines a cycle of the signal based on the reference periodic signal generated by the generation unit. One transmitter is
It is configured to transmit signals to other transmitters wirelessly or by wire,
The other transmitter is
An adjustment unit that adjusts the period of the reference periodic signal generated by the generation unit based on the received signal,
The determining means includes
19. The communication system according to claim 18, wherein the signal period is determined based on a reference period signal whose period is adjusted by the adjusting unit. A cycle adjustment transmitter for transmitting a cycle adjustment signal having a predetermined cycle is provided.
The transmitter is
Receiving means for receiving a period adjustment signal transmitted by the period adjustment transmitter;
Based on the received period adjustment signal, the adjustment means for adjusting the period of the reference period signal generated by the generation means,
The determining means includes
19. The communication system according to claim 18, wherein the signal period is determined based on a reference period signal whose period is adjusted by the adjusting unit. The transmitter is
Receiving means for receiving a signal transmitted by a GNSS satellite;
The communication system according to any one of claims 1 to 12, further comprising: a determination unit that determines a period of the signal based on the received signal.   The travel value calculation means for calculating at least one of the travel direction and the travel speed of the host vehicle based on the host vehicle position specified at a predetermined time interval by the specifying means. 21. The communication system according to any one of 21. An in-vehicle device that receives signals of the same period transmitted from at least three transmission points,
Means for storing position information of the transmission point;
First time difference acquisition means for acquiring a first arrival time difference of each transmitted signal when reaching the first point on the road;
Second time difference acquisition means for acquiring a second arrival time difference of each transmitted signal when reaching the second point after passing through the first point;
Specifying means for specifying the vehicle position of the second point based on the position information of the transmission point, the information on the first point, the first arrival time difference and the second arrival time difference. In-vehicle machine that features The information of the first point is
The position information of the first point, the distance information from the first point to each transmission point, the arrival time information of each signal from each transmission point to the first point, and the respective signals are synchronized. 24. The vehicle-mounted device according to claim 23, wherein the on-vehicle device is at least one of arrival time differences of the respective signals to the first point when the signal is being transmitted. An in-vehicle device that receives signals of the same period transmitted from at least three transmission points,
Means for storing position information of the transmission point;
Time difference acquisition means for acquiring the arrival time difference of each transmitted signal;
Synchronization deviation calculating means for calculating the synchronization deviation of the cycle of the transmitted signal in a predetermined area on the road;
An in-vehicle device comprising: a means for specifying a vehicle position based on a difference in arrival time acquired at a travel point of the host vehicle, a synchronization shift calculated by the synchronization shift calculation unit, and position information of the transmission point. .   A vehicle comprising the in-vehicle device according to any one of claims 23 to 25. Transmitters that transmit signals of the same period to each other,
Generating means for generating a reference period signal of a predetermined period;
Receiving means for receiving signals transmitted by other transmitters;
Adjusting means for adjusting the period of the reference periodic signal generated by the generating means based on the signal received by the receiving means;
A transmitter comprising: a determining unit configured to determine a cycle of the signal based on the reference periodic signal whose cycle is adjusted by the adjusting unit;

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