JP2009031241A - Vehicle position specifying system, on-vehicle apparatus, transmitter, time correcting system, and time correcting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle position specifying system capable of accurately specifying the travel position of an own vehicle, an on-vehicle apparatus, a transmitter, a time correcting system and a time correcting device. <P>SOLUTION: The on-vehicle apparatus 30 carries out positioning of an own vehicle position when the on-vehicle apparatus 30 enters an area R where communication with an optical beacon 10 is possible. The on-vehicle apparatus 30 receives a signal transmitted from the transmitter 20 immediately after passing through the area R (when the time elapsed after passing through the area R is short) and synchronizes the time of the on-vehicle apparatus 30 with that of the transmitter 20 in a pseudo manner. The on-vehicle apparatus 30 then receives a signal transmitted from the transmitter 20 and specifies the own vehicle position based on the received signal. The own vehicle position can be specified based on a distance from the transmitter 20 (or a stop line P), for instance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle position specifying system capable of specifying the position of a vehicle traveling on a road with high accuracy, an in-vehicle device and a transmitter constituting the vehicle position specifying system, and time correction for specifying the position with high accuracy. The present invention relates to a system and a time correction apparatus constituting the time correction system.

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, by detecting the position of the vehicle using a car navigation gyro sensor, acceleration sensor, GPS (Global Positioning System), etc., and identifying the position of the intersection based on the map data, The distance to the position of the stop line before the intersection at 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 a vehicle position specifying system that can specify the position of the host vehicle with high accuracy, an in-vehicle device and a transmitter that constitute the vehicle position specifying system, and a position with accuracy. It is an object of the present invention to provide a time correction system for specifying well and a time correction device constituting the time correction system.

  A vehicle position specifying system according to a first aspect of the present invention is a vehicle position specifying system including a transmitter that transmits a predetermined signal and an in-vehicle device that receives a signal transmitted by the transmitter. The in-vehicle device transmits a signal. Receiving means for receiving transmission time information for specifying time points, storage means for storing transmission point information for specifying signal transmission points, transmission time information received by the receiving means, and reception points for receiving the transmission time information And reception time correction means for correcting the reception time of the signal based on the transmission point information, and when a signal is received from the transmitter, the transmission time information of the signal, the transmission point information, and the reception time correction means And a specifying means for specifying the vehicle position based on the corrected reception time of the signal.

  According to a second aspect of the present invention, in the first aspect, the vehicle-mounted device includes positioning means for positioning the own vehicle position, and the reception time correction means measures the own vehicle position by the positioning means. The reception time of the signal is corrected based on the transmission time information received by the receiving means before or after positioning, the reception point where the transmission time information is received, and the transmission point information. And

  When the vehicle position specifying system according to a third aspect of the invention is the second aspect of the invention, the in-vehicle device receives the transmission time information by the measuring means for measuring the traveling distance and / or the traveling direction of the own vehicle and the receiving means, And receiving point specifying means for specifying the receiving point of the transmission time information based on the measured vehicle position and the result measured by the measuring means.

  According to a fourth aspect of the present invention, in the second or third aspect of the invention, the in-vehicle device is configured such that the in-vehicle device has a reliability of the vehicle position measured by the positioning means and / or a reception point specified by the reception point specifying means. The reception time correction means is configured to correct the reception time of the signal when the reliability determined by the determination means is larger than a predetermined threshold value. And

  According to a fifth aspect of the present invention, in the second or third aspect, when the vehicle-mounted device measures the vehicle position by the positioning means, the reception is performed within a specific distance from the measured vehicle position. A reception point determination unit that determines whether or not there is a reception point specified by the point specification unit, and the reception point correction unit determines the reception point of the signal when the reception point determination unit determines that there is a reception point. It is configured to correct.

  According to a sixth aspect of the present invention, in the fifth aspect, the in-vehicle device includes a determining unit that determines the specific distance according to a traveling state of the host vehicle.

  The vehicle position specifying system according to a seventh aspect of the present invention is the vehicle position specifying system according to any one of the second to sixth aspects, wherein the in-vehicle device sets the reliability of the own vehicle position when the own vehicle position is measured by the positioning means. The setting means to perform is provided.

  According to an eighth aspect of the present invention, in the seventh aspect, the in-vehicle device includes a detecting unit that detects whether the vehicle has passed a predetermined point, and the positioning unit is detected by the detecting unit. In this case, the vehicle position is measured, and the setting means is configured to set the reliability of the vehicle position to a predetermined value.

  According to a ninth aspect of the present invention, in the seventh aspect, the in-vehicle device includes satellite signal receiving means for receiving a satellite signal transmitted by a GNSS satellite, and the positioning means is a satellite that receives the satellite signal. When the signal is received, the vehicle position is measured, and the setting means sets the reliability of the vehicle position according to the reception status of the satellite signal received by the satellite signal receiving means. It is configured as described above.

  According to a tenth aspect of the present invention, in any one of the second to ninth aspects, the vehicle-mounted device is configured so that the in-vehicle device is in accordance with a moving distance of the own vehicle after the own vehicle position is measured by the positioning means. And a reducing means for reducing the reliability set by the setting means.

  According to an eleventh aspect of the present invention, there is provided the vehicle position specifying system according to any one of the second to ninth aspects, wherein the in-vehicle device sets the setting according to a lapse of time after positioning the own vehicle position by the positioning means. A reduction means for reducing the reliability set by the means is provided.

  According to a twelfth aspect of the present invention, in any one of the second to ninth aspects, the vehicle-mounted device may be configured such that when the in-vehicle device measures the own vehicle position by the positioning means, the measured own vehicle position and before positioning. And a reduction means for reducing the reliability of the reception point from the reliability set by the setting means in accordance with the moving distance to the reception point specified by the reception point specifying means.

  According to a thirteenth aspect of the present invention, in any one of the second to ninth aspects, the in-vehicle device determines the position of the own vehicle position and the positioning when the in-vehicle device measures the own vehicle position by the positioning means. A reduction means for reducing the reliability of the reception point from the reliability set by the setting means according to the passage of time from the reception point of the signal at the reception point previously specified by the reception point specifying means; It is characterized by that.

  According to a fourteenth aspect of the present invention, in any one of the first to thirteenth aspects, the in-vehicle device receives the transmission point information by the receiving unit and the transmission point of the transmission point information. Acquisition means for acquiring information for specifying the signal propagation time between the transmission time and the reception time correction means based on a value obtained by adding the signal propagation time to the transmission time specified by the transmission time information The signal reception time point is corrected.

  According to a fifteenth aspect of the present invention, in any one of the first to thirteenth aspects, the in-vehicle device and the transmitter include a time measuring unit, and the reception time correction unit is specified by transmission time information. The time value corresponding to the transmitted transmission time is used as the time value corresponding to the reception time of the signal whose transmission time is specified by the transmission time information, and the reception time of the signal is corrected. .

  According to a sixteenth aspect of the present invention, in any one of the first to thirteenth aspects, the in-vehicle device generates the reference period signal having a predetermined period, and the generation unit generates the reference period signal. A clocking means for timing based on a reference periodic signal; a reception point at which transmission time information is received by the receiving means; a transmission time specified by the transmission time information; and a period of the reference periodic signal based on the transmission point information The reception time correction means is configured to correct the reception time of the signal based on the time measured by the reference periodic signal corrected by the period correction means. It is characterized by that.

  According to a seventeenth aspect of the present invention, in any one of the first to third aspects, the in-vehicle device is specified by the reception point where the reception means receives the transmission time point information and the transmission time point information. Transmission time correction means for correcting the transmission time specified by the transmission time information based on the transmission time and the transmission point information.

  According to an eighteenth aspect of the present invention, in any one of the first to seventeenth aspects, the vehicle position specifying system includes a plurality of transmitters that transmit transmission time information, and the specifying means is specified by the transmission time information. The vehicle position is specified based on the transmission time and the reception time of the signal transmitted by each transmitter.

  According to a nineteenth aspect of the present invention, in any one of the first to eighteenth aspects, the in-vehicle device includes road information acquisition means for acquiring road information, and the specification means includes the road information. The present invention is characterized in that the vehicle position is specified based on road information acquired by the acquisition means.

  In the vehicle positioning system according to a twentieth aspect of the present invention, in any one of the first to nineteenth aspects, the transmitter includes a signal to be transmitted including information indicating that the signal is valid. The specifying means is configured to specify the position of the host vehicle when the information is included in the received signal.

  An in-vehicle device according to a twenty-first aspect of the present invention is an in-vehicle device that receives a predetermined signal, a receiving means for receiving transmission time information for specifying a signal transmission time, and a memory for storing transmission point information for specifying a signal transmission point. Means, a transmission time information received by the reception means, a reception point that received the transmission time information, and a reception time correction means that corrects the reception time of the signal based on the transmission point information, and a signal received, And a means for specifying the vehicle position based on the transmission time information of the signal, the transmission point information, and the reception time of the signal corrected by the reception time correction means.

  A transmitter according to a twenty-second aspect of the invention is characterized in that in the transmitter for transmitting a predetermined signal, the transmitter includes transmission means for transmitting transmission time point information for specifying a signal transmission time point.

  A time correction system according to a twenty-third aspect of the present invention is a time correction system comprising a transmitter that transmits a predetermined signal and a time correction device that receives the signal transmitted by the transmitter and corrects the time. The correction device includes: a receiving unit that receives transmission point information that specifies a signal transmission point; a storage unit that stores transmission point information that specifies a signal transmission point; the transmission point information received by the receiving unit; And a time correction means for correcting the time based on the reception point where the time point information is received and the transmission point information.

  In a time correction system according to a twenty-fourth invention, in the twenty-third invention, the time correction device includes positioning means for positioning its own position, and when the time correction means measures its own position with the positioning means, The time is corrected based on the transmission time information received by the receiving means before or after positioning, the reception point where the transmission time information is received, and the transmission point information.

  A time correction system according to a twenty-fifth aspect of the present invention is the time correction system according to the twenty-fourth aspect of the present invention, wherein when the time correction device receives the transmission time point information by a measuring unit that measures its own moving distance and / or moving direction and the receiving unit, Receiving point specifying means for specifying the receiving point of the transmission time point information based on the own position and the result measured by the measuring means.

  According to a twenty-sixth aspect of the present invention, in the twenty-fourth or twenty-fifth aspect, the time correction device is characterized in that the time correction device is a reliability of its own position measured by the positioning means and / or a reception point specified by the reception point specifying means. The time correction means is configured to correct the time when the reliability determined by the determination means is greater than a predetermined threshold value.

  A time correction system according to a twenty-seventh aspect of the present invention is the time correction system according to any one of the twenty-fourth to twenty-sixth aspects, wherein the time correction device sets the reliability of its own position when the positioning unit measures its own position. The setting means to perform is provided.

  A time correction apparatus according to a twenty-eighth aspect of the present invention is a time correction apparatus that receives a predetermined signal and corrects the time, and includes a receiving means for receiving transmission time information for specifying a signal transmission time, and a signal transmission point. Storage means for storing transmission point information to be identified, transmission time information received by the reception means, reception point from which the transmission time information has been received, and time correction means for correcting time based on the transmission point information It is characterized by that.

  In the first invention and the 21st invention, when the in-vehicle device mounted on the vehicle traveling on the road receives the transmission time information specifying the signal transmission time from the transmitter, the received transmission time information, The reception time of the signal is corrected based on the reception point that received the transmission time information and the transmission point information (position information of the transmitter). In this case, even when there is a time zone in which the transmitter cannot transmit a signal and the signal cannot be arbitrarily transmitted, the in-vehicle device can correct the reception time of the signal. The transmission point information can be stored in advance by the in-vehicle device, or can be received and stored from a transmitter or the like.

  The correction of the reception time is, for example, a pseudo value of the time between the transmitter and the in-vehicle device with a value obtained by adding a predetermined time to the transmission time of the signal specified by the transmission time information as the reception time in the in-vehicle device. Can be matched. Alternatively, the correction of the reception time point is made by using the transmission time point of the signal specified by the transmission time point information as the reception time point in the in-vehicle device, and calculating the relative time between the transmitter that transmits the transmission time point information and the in-vehicle device. Can also be matched. The predetermined time to be added is a signal propagation time determined by the distance between the transmission point of transmission time information and the reception point of receiving transmission time information. Thereby, both can synchronize time so that it may be understood which time in a transmitter is the time in a transmitter. It should be noted that the pseudo matching of the times is not limited to permanently correcting the clock of the in-vehicle device, and it is possible to temporarily or another clock. Any time may be used as long as it has a timekeeping function such as a counter as well as a clock.

  When the vehicle-mounted device receives a signal from the transmitter, the vehicle-mounted device identifies its own vehicle position based on the transmission time information of the received signal, the transmission point information, and the reception time of the corrected signal. For example, if the transmission time of the signal received by the in-vehicle device is t2, the time is already synchronized between the in-vehicle device and the transmitter, so the transmission time t2 when the transmitter transmits the signal The time point of the in-vehicle device is t2. Assuming that the reception time point when the signal is received by the vehicle-mounted device is t21, the arrival time ΔT required for the signal transmitted by the transmitter to reach the vehicle-mounted device is ΔT = t21−t2. The value obtained by multiplying ΔT by the radio wave propagation speed α is the distance from the transmitter to the vehicle-mounted device. The host vehicle position can be specified based on the position of the transmitter (transmission point information). In addition, the number of transmitters necessary for specifying the vehicle position may be at least one, and the entire vehicle position specifying system can be realized at low cost.

  In the second invention, the in-vehicle device measures the own vehicle position. The positioning of the vehicle position is, for example, when communicating with an optical beacon, when receiving a satellite signal with a GNSS receiver, or when receiving a signal from a DSRC, radio, or magnetic nail that can identify the signal reception point, etc. Can be done. When the vehicle-mounted device has measured the vehicle position, before or after positioning, when receiving the transmission time information specifying the signal transmission time from the transmitter, the received transmission time information, the reception that received the transmission time information The reception time of the signal is corrected based on the point and transmission point information (transmitter position information). In this case, it is not necessary to receive a signal from the transmitter at the time when the own vehicle position is measured, and the time when the own vehicle position is measured and the time when the signal is received may not be the same timing. Therefore, even when there is a time zone in which the transmitter cannot transmit a signal and the signal cannot be arbitrarily transmitted, the in-vehicle device can correct the reception time of the signal.

  In the third invention, when the in-vehicle device receives the transmission time information, the in-vehicle device receives the received transmission time information based on the measured vehicle position and the measurement result of the travel distance and / or travel direction of the vehicle. Identify the point. For the measurement of the travel distance and / or travel direction, for example, a vehicle speed sensor such as a wheel speed sensor, a gyro sensor, or an acceleration sensor can be used. That is, the reception point of the transmission time information can be obtained by adding the travel distance and / or travel direction traveled between the positioning time of the vehicle position and the reception time of the signal to the measured vehicle position. Alternatively, the reception point of the transmission time information is obtained by reversely calculating the travel distance and / or travel direction traveled between the signal reception time and the positioning time of the vehicle position with respect to the measured vehicle position. Can do. Thereby, the range which can correct | amend a reception time point can be extended also before the positioning of the own vehicle position before the position other than the point which measured the own vehicle position.

  In the fourth invention, the in-vehicle device determines the reliability of the measured vehicle position and / or the reliability of the reception point of the transmission time information. The reliability is, for example, an evaluation value indicating the reliability of the positioning accuracy of the measured vehicle position and the reliability of the position accuracy of the reception point of the transmission time information. The in-vehicle device corrects the reception time of the signal when the determined reliability is greater than a predetermined threshold. As a result, when the positioning accuracy of the vehicle position is high, or when the position accuracy of the reception point of the transmission time information is high, the vehicle position can be accurately identified by correcting the reception time point. When the positioning accuracy of the position is low, or when the position accuracy of the reception point of the transmission time information is low, it is possible to prevent an erroneous own vehicle position from being specified without correcting the reception time point.

  In the fifth aspect, when the vehicle position is measured, the in-vehicle device determines whether or not there is a transmission point information reception point within a specific distance from the measured vehicle position. The specific distance (distance range) may be a range in which the reliability of positioning accuracy is considered to be greater than a predetermined threshold among the distances traveled after the position of the host vehicle is measured, or when the host vehicle position is determined A range in which the reliability of positioning accuracy is considered to be greater than a predetermined threshold among the distances that have already traveled up to this point may be used. When it is determined that there is a reception point, the in-vehicle device corrects the reception time of the signal on the assumption that the reliability of the reception point is larger than a predetermined threshold. Thereby, the range which can correct | amend a reception time point can be extended also before the positioning of the own vehicle position before the position other than the point which measured the own vehicle position.

  In the sixth invention, the in-vehicle device determines the specific distance (distance range) according to the traveling state of the host vehicle. The traveling state is when the vehicle is traveling straight, when traveling along a curve, when stopped, etc. For example, when traveling on a curve compared to when traveling straight, the traveling distance Therefore, the distance range decreases as the distance traveled along the curve increases, and the distance range increases as the distance traveled along the curve decreases. Thereby, it is possible to determine a distance range in which the reliability of positioning accuracy is greater than a predetermined threshold regardless of the traveling state of the host vehicle.

  In the seventh invention, the in-vehicle device sets the reliability of the own vehicle position when the own vehicle position is measured. The positioning of the vehicle position is, for example, when communicating with an optical beacon, when receiving a satellite signal with a GNSS receiver, or when receiving a signal from a DSRC, a radio, or a magnetic nail that can identify the signal reception point, etc. The reliability can be set according to the positioning accuracy of the positioning method.

  In the eighth invention, the in-vehicle device detects whether or not the vehicle has passed a predetermined point. The passage of the predetermined point can be detected by communication with an optical beacon, for example. When the in-vehicle device detects that the vehicle has passed a predetermined point, the vehicle-mounted device measures the vehicle position and sets the reliability of the vehicle position to a predetermined value. Thereby, the reliability according to the positioning accuracy of the own vehicle position by an optical beacon can be set, for example.

  In the ninth invention, when the vehicle-mounted device receives the satellite signal transmitted by the GNSS satellite, the vehicle-mounted device measures the own vehicle position, and sets the reliability of the own vehicle position according to the reception status of the received satellite signal. To do. As the reception status of the satellite signal, for example, the number of supplemented satellites, the reception intensity of the received satellite signal, or the distortion of the correlation function can be used. Thereby, the reliability according to the positioning accuracy of the own vehicle position by a GNSS satellite can be set, for example.

  In the tenth invention, the in-vehicle device reduces the set reliability according to the moving distance of the own vehicle after measuring the own vehicle position. Since errors accumulate in the own vehicle position according to the moving distance of the own vehicle, the reliability set at the time of positioning the own vehicle position is gradually decreased according to the moving distance of the own vehicle. As a result, it is possible to prevent the reception time point from being erroneously corrected due to an error in the vehicle position that occurs according to the movement distance, and it is possible to maintain a highly reliable correction of the reception time point. In addition to the moving distance, the set reliability can be reduced in accordance with the passage of time after positioning the vehicle position.

  In the eleventh aspect, the in-vehicle device reduces the set reliability according to the passage of time after positioning the own vehicle position. Since errors accumulate in the own vehicle position only with the passage of time, the reliability set at the time of positioning the own vehicle position is gradually decreased with the passage of time. Thereby, it is possible to prevent the reception time point from being erroneously corrected due to an error in the own vehicle position that occurs with the passage of time, and it is possible to maintain a highly reliable correction of the reception time point. In addition to the lapse of time, the set reliability can be reduced according to the movement distance after positioning the vehicle position.

  In the twelfth invention, when the on-vehicle device measures the own vehicle position, the on-vehicle device determines the own vehicle position according to the moving distance between the measured own vehicle position and the reception point that received the transmission time information before the positioning. The reliability of the receiving point is reduced from the reliability set at the time of positioning. As a result, it is possible to prevent the reception time point from being erroneously corrected due to a positioning error that occurs according to the distance from the positioning point of the vehicle position, and to output a signal before highly reliable positioning is performed. Even when it is received, it is possible to correct the reception time, and it is possible to specify the vehicle position at an earlier timing.

  In the thirteenth invention, when the vehicle-mounted device measures the own vehicle position, according to the time lapse between the positioning time of the own vehicle position and the reception time of the signal at the receiving point specified before positioning, The reliability of the receiving point is reduced from the reliability set at the time of positioning the vehicle position. As a result, it is possible to prevent the reception time point from being erroneously corrected due to the positioning error that occurs according to the time that has gone back in the past from the positioning time point of the vehicle position, and highly reliable positioning is performed. Even when a signal has been received before, the reception time can be corrected, and the vehicle position can be specified at an earlier timing.

  In the fourteenth invention, the in-vehicle device acquires information for specifying the signal propagation time between the reception point where the transmission time information is received and the transmission point of the transmission time information. For example, it may be information for specifying the distance between the reception point and the transmission point, or the signal propagation time itself between the transmission point and the reception point. In addition, as information for specifying the distance between the reception point and the transmission point, for example, information on the distance between the transmission point and the reception point, position information of the transmission point and the reception point, position information of the transmission point and reception Information on the distance from the point to the stop line, information on the signal direction (directivity) from the transmitter, road shape information, and the like. The vehicle-mounted device corrects the signal reception time based on the value obtained by adding the signal propagation time to the transmission time specified by the transmission time information. For example, let t1 'be the reception time point at which the transmitter transmits a signal at the transmission time t1, and the in-vehicle device receives the signal at the reception point. When the propagation time of the signal from the transmitter to the reception point is Δt1, the in-vehicle device corrects the reception time of the signal from the time t1 ′ to the time t1 + Δt1. Since the point in time of the transmitter when the vehicle-mounted device receives the signal is t1 + Δt1, by correcting the time point when the signal is received by the vehicle-mounted device to t1 + Δt1, the time in the vehicle-mounted device and the time in the transmitter are matched in a pseudo manner The time can be synchronized between the two. It should be noted that the pseudo matching of the times is not limited to permanently correcting the clock of the in-vehicle device, and it is possible to temporarily or another clock. Any time may be used as long as it has a timekeeping function such as a counter as well as a clock.

  In the fifteenth aspect, the in-vehicle device and the transmitter are provided with time measuring means. As a timekeeping means, for example, each of the transmitter and the vehicle-mounted device includes a counter that adds “1” every 0.1 ns. The in-vehicle device uses the time value (counter value) corresponding to the transmission time specified by the transmission time information as the time value corresponding to the reception time of the signal whose transmission time is specified by the transmission time information. Correct. For example, the transmitter transmits a counter value (for example, 0) at the time of transmission of the signal together with the signal as transmission time information. The in-vehicle device receives the signal at the reception point, and sets the counter of the in-vehicle device to a counter value 0 that is transmission time information. That is, the counter value (0) at the time of transmission when the transmitter transmits a signal is matched with the counter value (0) of the vehicle-mounted device at the time of reception when the signal is received. Note that the counter value at the time of signal transmission is an example, and is not limited to zero.

  Then, when the counter value of the vehicle-mounted device at the time of reception when the signal is received by the vehicle-mounted device is different from the counter value at the time of transmission of the signal, when the transmitter, the reception point, and the vehicle-mounted device are on a straight line, This means that the vehicle-mounted device has moved away from the point where the counter value matches (reception point) by a distance corresponding to the difference in the counter value. If the position of the transmitter and the position of the reception point are known, the vehicle position can be specified. Further, if the positions of the transmitter and the reception point are known, the vehicle position can be specified as the distance from the transmitter.

  In the sixteenth invention, the vehicle-mounted device times the signal reception time. In this case, the timekeeping means is, for example, a clock or a timer, and the vehicle-mounted device generates a reference cycle signal (reference clock signal) having a predetermined cycle with an internal transmitter so as to drive the clock or the timer. The vehicle-mounted device corrects the cycle of the reference periodic signal based on the reception point that has received the transmission point information, the transmission point specified by the transmission point information, and the transmission point information. More specifically, the period (or frequency) of the reference period signal is extracted from the signal transmitted from the transmitter, and the period (frequency) of the reference period signal is adjusted to be the same period as the extracted period. The timer or the clock is corrected based on the adjusted reference period signal. Thereby, the timer or clock in the vehicle-mounted device can be synchronized with the timer or clock of the transmitter.

  In the seventeenth invention, the vehicle-mounted device receives the transmission point information, the transmission point specified by the transmission point information, and the transmission point specified by the transmission point information based on the transmission point information. Correct. For example, let t1 'be the reception time point at which the transmitter transmits a signal at the transmission time t1, and the in-vehicle device receives the signal at the reception point. When the propagation time of the signal from the transmitter to the reception point is Δt1, the in-vehicle device corrects the transmission time of the received signal from time t1 to t1′−Δt1. Since the point in time of the transmitter when the in-vehicle device receives the signal is t1′−Δt1, the time at the in-vehicle device and the time at the transmitter are corrected by correcting the time when the transmitter has transmitted the signal to t1′−Δt1. And the time can be synchronized with each other.

  In the eighteenth aspect, the in-vehicle device specifies the vehicle position based on the transmission time specified by the transmission time information and the reception time of the signal transmitted by each transmitter. For example, by using three transmitters, the vehicle position can be specified as an intersection of three spherical surfaces having the same distance from each transmitter.

  In the nineteenth invention, the in-vehicle device acquires road information and identifies the vehicle position based on the acquired road information. For example, the position of the vehicle-mounted device is specified as a distance from the transmission point based on the transmission point (the position of the transmitter), and on the road based on road information (for example, can be obtained from a map database). Thus, the point where the distance from the transmission point is specified can be specified as the vehicle position.

  In the twentieth invention, the transmitter transmits the signal to be transmitted by including information indicating that the signal is valid. When the information is included in the received signal, the in-vehicle device identifies the vehicle position. For example, the vehicle-mounted device specifies the vehicle position (positioning) only when it is confirmed that the received signal includes information (for example, a valid flag) indicating that the signal is valid. As a result, it is possible to prevent the vehicle position from being erroneously specified by receiving a signal that is not an original positioning signal.

  In the twenty-second aspect, the transmitter transmits transmission time information for specifying a signal transmission time. Thereby, when the vehicle-mounted device receives a signal, the vehicle-mounted device can acquire the transmission time point when the signal is transmitted from the transmitter.

  In the twenty-third invention and the twenty-eighth invention, when the time correction device receives transmission time information specifying the signal transmission time from the transmitter, the received transmission time information, the reception point from which the transmission time information is received. The time is corrected based on the transmission point information (position information of the transmitter). In this case, even when there is a time zone in which the transmitter cannot transmit a signal and the signal cannot be arbitrarily transmitted, the time correction device can correct the time. The transmission point information can be stored in advance by the time correction device, or can be received from a transmitter or the like and stored.

  The time correction is performed by, for example, using a value obtained by adding a predetermined time to the transmission time point of the signal specified by the transmission time point information as a reception time point at the time correction device, and setting the time between the transmitter and the time correction device in a pseudo manner. Can match. Alternatively, the time correction is performed by setting the transmission time of the signal specified by the transmission time information as the reception time at the time correction device and simulating the relative time between the transmitter that transmits the transmission time information and the time correction device. Can also be matched. The predetermined time to be added is a signal propagation time determined by the distance between the transmission point of transmission time information and the reception point of receiving transmission time information. Thereby, both can synchronize time so that it may be understood which time in a transmitter is a certain time in a time correction device. It should be noted that the pseudo matching of the times is not limited to permanently correcting the clock of the time correction device, and it is possible to temporarily or another clock. Any time may be used as long as it has a timekeeping function such as a counter as well as a clock.

  In the twenty-fourth aspect, the time correction device measures its own position. For example, when the position of its own position is communicated with an optical beacon, when a satellite signal is received by a GNSS receiver, when a signal is received from a DSRC, a radio, a magnetic nail, or the like that can identify the reception point of the signal, etc. Can be done. When the time correction device has measured its own position, before or after positioning, when receiving the transmission time information specifying the signal transmission time from the transmitter, the time correction device has received the received transmission time information and the transmission time information. The time is corrected based on the reception point and transmission point information (position information of the transmitter). In this case, it is not necessary to receive a signal from the transmitter at the time when the own position is measured, and the time when the position is measured and the time when the signal is received may not be the same timing. Therefore, even when there is a time zone in which the transmitter cannot transmit a signal and the signal cannot be arbitrarily transmitted, the time correction device can correct the time.

  In the twenty-fifth aspect, when the time correction device receives the transmission time point information, the time correction device receives the received transmission time point information on the basis of the measured position and its movement distance and / or movement direction measurement result. Identify the point. For example, a sensor such as a wheel speed sensor, a gyro sensor, and an acceleration sensor, or a GNSS receiver and a map database can be used for measuring the movement distance and / or the movement direction. That is, the reception point of the transmission time information can be obtained by adding the movement distance and / or movement direction moved from the positioning time of the own position to the reception time of the signal to the own position of the positioning. Alternatively, the reception point of the transmission time information is obtained by calculating back the movement distance and / or movement direction moved from the reception time of the signal to the positioning time of the own position with respect to the own position of the positioning. Can do. Thereby, the range which can correct | amend time can be extended also before the positioning of the own position other than the point which measured the own position, or after positioning.

  In the twenty-sixth aspect of the invention, the time correction apparatus determines the reliability of the measured position and / or the reliability of the reception point of the transmission time information. The reliability is, for example, an evaluation value indicating the reliability of the positioning accuracy of the position of the positioning itself and the reliability of the position accuracy of the reception point of the transmission time information. The time correction device corrects the time when the determined reliability is greater than a predetermined threshold. Thereby, when the positioning accuracy of its own position is high, or when the positioning accuracy of the reception point of the transmission time information is high, the time can be corrected with high accuracy, and when the positioning accuracy of its own position is low, or When the position accuracy of the reception point of the transmission time information is low, it is possible to prevent correction to an incorrect time without correcting the time.

  In the twenty-seventh aspect, the time correction apparatus sets the reliability of its own position when measuring its own position. For example, when the position of its own position is communicated with an optical beacon, when a satellite signal is received by a GNSS receiver, when a signal is received from a DSRC, a radio, a magnetic nail or the like that can identify the reception point of the signal, etc. The reliability can be set according to the positioning accuracy of the positioning method.

  In the present invention, even if the signal cannot be transmitted arbitrarily because there is a time zone in which the transmitter cannot transmit the signal, the in-vehicle device can correct the reception time of the signal and It can be specified with high accuracy. In addition, the number of transmitters necessary for specifying the vehicle position may be at least one, and the entire vehicle position specifying system can be realized at low cost.

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 vehicle position specifying system according to the present invention. The vehicle position specifying system according to the present invention can be realized particularly as a road-to-vehicle communication system, and is installed at a predetermined position in the vicinity of a road, an optical beacon 10 for positioning the own vehicle, and transmits a predetermined signal. And a vehicle-mounted device 30 mounted on the vehicle. In addition, it can replace with the optical beacon 10 and can also measure the own vehicle position with a GPS receiver or the like.

  The optical beacon 10 is installed so as to be communicable with the vehicle-mounted device 30 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.

  In the vehicle position specifying system according to the present invention, when the in-vehicle device 30 enters the region R in which communication with the optical beacon 10 is possible, the in-vehicle device 30 measures the own vehicle position. Since there is a time zone in which the transmitter 20 cannot arbitrarily transmit a signal and cannot be transmitted, the transmitter 20 transmits a predetermined signal only at a transmittable timing. Therefore, there is a case where a signal cannot be received from the transmitter 20 when the in-vehicle device 30 is in the region R in which communication with the optical beacon 10 is possible.

  The in-vehicle device 30 receives the signal transmitted by the transmitter 20 immediately after passing through the region R (when the time has passed after passing through the region R), and simulates the time between the in-vehicle device 30 and the transmitter 20. Synchronize. Note that the time synchronization means, for example, that the time between the transmitter 20 and the vehicle-mounted device 30 is made to coincide in a pseudo manner, or the relative time between the transmitter 20 and the vehicle-mounted device 30 is simulated. To match. Thereby, it is understood which time in the transmitter 20 is a certain time in the in-vehicle device 30.

  Thereafter, the in-vehicle device 30 receives the signal transmitted by the transmitter 20 and specifies the vehicle position based on the received signal. The own vehicle position can be specified by the distance from the transmitter 20 (or the stop line P), the distance from the optical beacon 10, and the like, for example. Note that the pseudo matching of the times is not limited to permanently correcting the clock of the in-vehicle device 30, but may be set temporarily or with another clock.

  FIG. 2 is a block diagram showing the configuration of the vehicle position specifying system according to the present invention. The optical beacon 10 includes a light emitter / receiver, a communication unit 11 having a communication function with the vehicle-mounted device 30, 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 40, A storage unit 14 that stores position information related to a region R on a road that can communicate with the in-vehicle device 30 and transmission point information of the transmitter 20 is provided. Various types of information stored in the storage unit 14 of the optical beacon 10 can be received from the central device 40. 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 20 includes a communication unit 21, a control unit 22, and the like. For example, the communication unit 21 transmits radio waves in the frequency band of the VHF / UHF band to the in-vehicle device 30. The communication unit 21 includes a crystal oscillator that generates a reference clock signal, a carrier wave generation circuit, a modulation circuit, and the like (not shown), and generates 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 21 performs frequency modulation of 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 22, and after modulation through an antenna (not shown) The carrier wave is transmitted.

  The frequency band used by the transmitter 20 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.

  The transmitter 20 transmits a predetermined signal to the in-vehicle device 30. However, the transmitter 20 cannot transmit a signal at an arbitrary timing, and there is a time zone in which a signal cannot be transmitted based on a predetermined specification (for example, ITS wireless specification). The transmitter 20 repeatedly transmits a signal to the in-vehicle device 30 at a predetermined timing in a transmittable time zone.

  The in-vehicle device 30 includes a first communication unit 31 having a communication function with the optical beacon 10 using an infrared ray, a second communication unit 32 having a communication function with the transmitter 20, and a control unit for controlling the operation of the in-vehicle device 30. 33, a storage unit 34, a display unit 35, an operation unit 36, a GPS reception unit 37 having a GPS (Global Positioning System) reception function, a sensor unit 38 including vehicle sensors such as a wheel speed sensor, a gyro sensor, and an acceleration sensor, a map database 39 and the like.

  The first communication unit 31 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 vehicle-mounted device 30. A region R on the road indicates a region where the in-vehicle device 30 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 30 while being able to transmit downlink information from the optical beacon 10 with respect to the vehicle equipment 30. On the other hand, area | region R2 is an area | region which can transmit downlink information with respect to the vehicle equipment 30 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 30 enters the region R, the first communication unit 31 receives the downlink information and outputs the received downlink information to the control unit 33.

  When receiving the downlink information, the in-vehicle device 30 repeatedly transmits uplink information including the vehicle ID to the optical beacon 10 through the first communication unit 31 at a predetermined uplink period.

  When the optical beacon 10 receives the uplink information, the optical beacon 10 performs downlink switching, lane notification information, predetermined position information (for example, position information of the region R, transmission point information of the transmitter 20, stop line) Downlink information after downlink switching such as a distance L1 to P) is transmitted to the in-vehicle device 30. 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 second communication unit 32 receives the signal transmitted by the transmitter 20. More specifically, the second communication unit 32 includes a demodulation circuit, receives the radio wave transmitted by the transmitter 20, demodulates the received radio wave, and extracts the original signal. The second communication unit 32 calculates a signal reception time point based on the extracted signal, and outputs the calculated reception time point to the control unit 33. It is also possible to use the average value or the median value after calculating the reception time points a plurality of times within a predetermined time. According to such a method, it is possible to reduce the influence of noise or the like and obtain a stable reception time point. The signal reception time can be calculated not only at the rising portion of the signal waveform but also at the falling portion.

  FIG. 4 is an explanatory diagram illustrating an example of a data structure included in a signal transmitted by the transmitter 20. As shown in FIG. 4, the signal transmitted by the transmitter 20 is composed of, for example, a time correction signal and a data area. In the data area, a valid flag indicating that the signal is valid, a signal transmission time point, and the like. It includes information such as transmission time information to be identified (for example, time format information measured by the transmitter 20 or a counter value of a counter counted at a predetermined time interval). Note that the transmission time of the time correction signal and the data may be the same or different.

  FIG. 5 is an explanatory diagram showing an example of obtaining a signal reception time point. The upper part of FIG. 5A schematically shows an example of a signal received from the transmitter 20, and the lower part is a replica signal for performing correlation processing (pattern matching) stored in advance by the in-vehicle device 30. As shown in FIG. 5 (a), when the signal received by the vehicle-mounted device 30 and the replica signal are sampled at a predetermined time interval, and the waveform and the waveform of the replica signal coincide with each other, as shown in FIG. The correlation value of the signal shows a sharp peak. As shown in FIG. 5B, the second communication unit 32 obtains a signal reception time when a sharp peak of the correlation value is obtained. The method for obtaining the reception time point is not limited to time axis correlation processing, and correlation processing in the frequency domain can also be performed. When there is an influence of a delayed wave due to multipath, the correlation has two or more peaks as shown in FIG.

  FIG. 6 is an explanatory diagram showing an example of the procedure for specifying the vehicle position. The control unit 33 measures the vehicle position based on the position information of the region R received through the first communication unit 31 when the in-vehicle device 30 exists in the region R. That is, the position of the region R is measured as the own vehicle position. When the own vehicle position is measured, the control unit 33 sets an evaluation value (reliability) indicating the reliability of the positioning accuracy of the own vehicle position to a predetermined value (for example, 90 in the case of the optical beacon 10). That is, the control unit 33 has a function of setting an evaluation value indicating the reliability of the positioning accuracy of the vehicle position. A function for setting the evaluation value can be provided outside the control unit 33.

  The control unit 33 measures the travel distance (travel distance), travel direction, and the like of the vehicle based on the sensor signal output from the sensor unit 38. The control unit 33 sets the evaluation value at the time when the vehicle position is measured, and then decreases the set evaluation value at a predetermined rate according to the sensor signal. Thereby, the control part 33 can grasp | ascertain the reduction condition of positioning accuracy in consideration of the error accumulate | stored in the own vehicle position according to a travel distance and a travel direction. Note that time can be added to decrease the evaluation value. When the control unit 33 receives a signal from the transmitter 20 through the second communication unit 32 (for example, time t1), whether or not the evaluation value is larger than a predetermined threshold (that is, the positioning accuracy is sufficiently reliable) If the evaluation value is equal to or greater than a predetermined threshold value, the reception time is corrected by the received signal. If the evaluation value is smaller than the threshold value, an error exceeding the allowable range is detected in the vehicle position. As a result, the reception time is not corrected. In the example of FIG. 6, the reception time is corrected. In addition, the control part 33 can also determine that the evaluation value in the time of having received the signal from the transmitter 20 through the 2nd communication part 32 before measuring the own vehicle position is larger than a predetermined threshold value. .

  The correction of the reception time is performed based on the transmission time specified by the transmission time information of the signal acquired from the signal received through the second communication unit 32 and acquired. In this case, the signal reception point (position A, which serves as a reference position for specifying the vehicle position) is determined from the vehicle position measured by the optical beacon 10 and the positioning position when the signal is received thereafter. The travel distance and travel direction can be determined. Thereby, the in-vehicle device 30 can synchronize the time in a pseudo manner so that at time A, it can be determined which time in the in-vehicle device 30 is in the transmitter 20.

  After correcting the reception time at the position A, the control unit 33 repeatedly receives a signal (including transmission time information) transmitted from the transmitter 20 through the second communication unit 32 (for example, time t2, t3, …). The control unit 33 acquires the transmission time information of the signal from the received signal, and the time difference between the transmission time specified by the acquired transmission time information and the reception time of the signal (that is, the signal is transmitted from the transmitter 20 to the vehicle. The vehicle position (for example, position B, position C,...) Is specified by obtaining the distance to the transmitter 20 based on the arrival time until the vehicle 30 is reached.

  For example, if the transmission time of the signal received by the vehicle-mounted device 30 is t2, the vehicle-mounted device 30 is at the position A, and the vehicle-mounted device 30 and the transmitter 20 are already synchronized in time. The time point of the vehicle-mounted device 30 at the transmission time point t2 when the signal 20 is transmitted is t2 itself. Assuming that the reception time point when the signal is received by the vehicle-mounted device 30 is t21, the arrival time ΔT required until the signal transmitted by the transmitter 20 is received by the vehicle-mounted device 30 is ΔT = t21−t2. A value obtained by multiplying ΔT by the radio wave propagation speed α is a distance from the transmitter 20 to the vehicle-mounted device 30. Therefore, the in-vehicle device 30 can continue to specify the position of the vehicle every time it is received only by repeatedly receiving the signal transmitted from the transmitter 20 after passing through the position A.

  FIG. 7 is an explanatory diagram showing an example of correction at the time of signal reception. For example, assume that the transmitter 20 transmits a signal at time t1 after the vehicle-mounted device 30 determines the position of the host vehicle at the position R. The transmitter 20 cannot transmit a signal at an arbitrary timing as described above. This signal includes a transmission time t1 as transmission time information. The in-vehicle device 30 receives a signal at time t <b> 1 ′ in the in-vehicle device 30. When the propagation time of the signal from the transmitter 20 to the reception point of the signal is Δt1, the in-vehicle device 30 corrects the reception time of the signal from t1 ′ to t1 + Δt1. Since the time of the transmitter 20 is t1 + Δt1 when the vehicle-mounted device 30 receives the signal, the time when the vehicle-mounted device 30 receives the signal is corrected to t1 + Δt1, so that a certain time in the vehicle-mounted device 30 is any of the transmitter 20 The time can be pseudo-synchronized so that it can be seen whether it is time.

  The signal propagation time Δt1 is the distance between the transmitter 20 and the reception point, such as the absolute position of the transmitter 20 and the reception point (position A) of the signal transmitted at time t1, or the relative position from a predetermined point. Etc. The reception point of the signal transmitted at time t1 is obtained by adding the travel distance and travel direction traveled between the time of positioning of the vehicle position and the time of reception of the signal to the position of the vehicle measured by the optical beacon 10. Can be sought.

  The transmitter 20 then transmits a signal at time t2. This signal includes transmission time t2 as transmission time information. The in-vehicle device 30 receives a signal at time t21 in the in-vehicle device 30. Since the vehicle-mounted device 30 has already synchronized the time between the vehicle-mounted device 30 and the transmitter 20 when passing the position A, the vehicle-mounted device 30 at the transmission time t2 when the transmitter 20 transmits a signal. Is the time t2. When the reception time when the signal is received by the vehicle-mounted device 30 is t21, the arrival time ΔT required until the signal transmitted by the transmitter 20 is received by the vehicle-mounted device 30 is ΔT = t21−t2. A value obtained by multiplying ΔT by the radio wave propagation speed α is a distance from the transmitter 20 to the vehicle-mounted device 30. Thereby, the vehicle equipment 30 can identify the own vehicle position based on the height information of the vehicle equipment 30 itself and the position information of the transmitter 20.

  FIG. 8 is an explanatory diagram showing another example of correction at the time of signal reception. In this case, each of the transmitter 20 and the vehicle-mounted device 30 includes a counter that adds “1” every predetermined time interval (for example, 0.1 ns). Each counter is composed of, for example, 40-bit data, and is reset to 0 every 10 seconds. Assume that after the in-vehicle device 30 measures the position of the vehicle at the position R, the transmitter 20 transmits a counter value (for example, 0) at the time of signal transmission along with the signal as transmission time information. The in-vehicle device 30 receives the signal and sets the counter of the in-vehicle device 30 to a counter value 0 which is transmission time information. That is, the counter value (0) at the time of transmission when the transmitter 20 transmits a signal is matched with the counter value (0) at the time of reception when the signal is received by the in-vehicle device 30. Note that the counter value at the time of signal transmission is an example, and is not limited to zero. The signal reception point (position A) is obtained by adding, to the own vehicle position measured by the optical beacon 10, the travel distance and travel direction traveled from the time when the signal was received until the time when the signal was received. Can do.

  Thereby, when the in-vehicle device 30 passes through the position A, the counter value at the time of transmission of the signal transmitted by the transmitter 20 matches the counter value at the time of reception when the in-vehicle device 30 receives the signal. Assume that the transmitter 20 subsequently transmits a signal when the counter reaches “10000000”, for example. This signal includes a counter value “10000000” as transmission time information. The in-vehicle device 30 receives the signal, and the counter of the in-vehicle device 30 at the time of reception is set to “9997000”. When the counter value of the vehicle-mounted device 30 at the time of reception when the signal is received by the vehicle-mounted device 30 is different from the counter value at the time of transmission of the signal, the vehicle-mounted device 30 is connected to the transmitter 20 by a distance corresponding to the difference of the counter value. It ’s close. For example, since the difference between the counter values is “3000”, the in-vehicle device 30 has approached the transmitter 20 by a distance (approximately 90 m) in which radio waves propagate during 3000 × 0.1 ns, that is, 300 ns. Therefore, the vehicle position can be specified based on the position A. In addition, if the antenna of the position A, the transmitter 20, and the vehicle-mounted device 30 is substantially in a straight line, the vehicle-mounted device 30 is separated from the position A by about 90 m and approaches the transmitter 20 by about 90 m.

  FIG. 9 is an explanatory diagram showing another example of correction at the time of signal reception. For example, assume that the transmitter 20 transmits a signal at time t1 after the vehicle-mounted device 30 determines the position of the host vehicle at the position R. This signal includes a transmission time t1 as transmission time information. The in-vehicle device 30 receives a signal at time t <b> 1 ′ in the in-vehicle device 30. Assuming that the signal propagation time from the transmitter 20 to the signal reception point is Δt1, the in-vehicle device 30 corrects the signal transmission time from t1 to t1′−Δt1. Since the time point of the transmitter 20 when the in-vehicle device 30 receives the signal is t1′−Δt1, the time point in the in-vehicle device 30 is corrected by correcting the time point when the transmitter 20 transmits the signal to t1′−Δt1. Can be pseudo-synchronized so that the time at the transmitter 20 can be known.

  The signal propagation time Δt1 is the distance between the transmitter 20 and the reception point, such as the absolute position of the transmitter 20 and the reception point (position A) of the signal transmitted at time t1, or the relative position from a predetermined point. Etc. The reception point of the signal transmitted at time t1 is obtained by adding the travel distance and travel direction traveled between the time of positioning of the vehicle position and the time of reception of the signal to the position of the vehicle measured by the optical beacon 10. Can be sought.

  The transmitter 20 then transmits a signal at time t2. This signal includes transmission time t2 as transmission time information. The in-vehicle device 30 receives the signal at the time t2 ′ in the in-vehicle device 30 and corrects the transmission time from t2 to t21 ′. The transmission time t21 'can be obtained by t21' = t2 + (t1 '-[Delta] t1) -t1. Since the vehicle-mounted device 30 has already synchronized the time between the vehicle-mounted device 30 and the transmitter 20 when passing the position A, the vehicle-mounted device 30 at the transmission time t21 ′ when the transmitter 20 transmits a signal. The time at 30 is t21 ′ itself. The arrival time ΔT required for the signal transmitted from the transmitter 20 to be received by the in-vehicle device 30 is ΔT = t2′−t21 ′. A value obtained by multiplying ΔT by the radio wave propagation speed α is a distance from the transmitter 20 to the vehicle-mounted device 30. Thereby, the vehicle equipment 30 can identify the own vehicle position based on the height information of the vehicle equipment 30 itself and the position information of the transmitter 20.

  The display unit 35 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 36 includes various operation panels and functions as a user interface between the driver and the vehicle-mounted device 30. For example, the operation unit 36 receives an operation for starting or stopping the operation of the in-vehicle device 30 by the operation of the driver.

  The GPS receiver 37 has a GPS reception function such as DGPS (differential GPS) or RTK-GPS (Real-Time Kinematic GPS), receives radio waves from a plurality of GPS (GNSS) satellites, and measures the position of the vehicle. . The map database 39 has road information, and the GPS 37 collates with the road information to determine the position of the vehicle with higher accuracy.

  The storage unit 34 stores information received through the first communication unit 31 and the second communication unit 32. The storage unit 34 stores an evaluation value indicating reliability of positioning accuracy, a threshold value for determining the magnitude of the evaluation value, data calculated by the control unit 33, and the like.

  FIG. 10 is an explanatory diagram showing an example of reliability evaluation of positioning accuracy. FIG. 10 shows the reliability of positioning accuracy and whether or not the reception time can be corrected. As shown in FIG. 10, when communication with an optical beacon is performed or when position information is acquired from a GPS receiver, the evaluation value indicating the reliability of positioning accuracy is raised to a predetermined value (setting) To do). The evaluation value to be set can be set to a different value depending on the accuracy of the positioning method.

  The evaluation value is set to a predetermined value at the time when the own vehicle position is measured, and thereafter, the evaluation value is decreased at a predetermined ratio according to the passage of time, the traveling distance of the own vehicle, and the traveling direction. When a signal is received from the transmitter 20 after positioning the vehicle position, if the evaluation value at the time of reception is equal to or greater than a predetermined threshold (for example, 50) (signals a2 and a4 in FIG. 10), Correct the reception time. In addition, when a signal is received from the transmitter 20 after positioning the vehicle position, if the evaluation value at the time of reception is smaller than a predetermined threshold (signals a1, a3, a5 in FIG. 10), reception is performed. Do not correct the time.

  As a result, when the positioning accuracy of the vehicle position is high, the reception time point can be corrected and the vehicle position can be accurately identified. When the positioning accuracy of the vehicle position is low, the reception time point correction is performed. It is possible to prevent an erroneous vehicle position from being specified without performing the operation. Further, the reliability can be set according to the positioning accuracy of the positioning method. Further, it is possible to prevent the reception time point from being erroneously corrected due to an error in the vehicle position that occurs according to the moving distance or the elapsed time, and it is possible to maintain a highly reliable correction of the reception time point.

  FIG. 11 is an explanatory diagram showing numerical examples of evaluation values. As shown in FIG. 11, an evaluation value table in which a positioning method and reliability evaluation values are associated can be stored in the storage unit 34. For example, at the time of communication with an optical beacon, the vehicle position can be limited to the communication area with the optical beacon, and the vehicle position can be measured with high accuracy, so the evaluation value is set to 90.

  Further, when the solution is obtained by RTK-GPS (carrier wave synchronization type), the evaluation value is set to 90 because the influence of multipath is small and the vehicle position can be measured with high accuracy. Further, when a solution is obtained by GPS (code synchronization type), for example, an evaluation value is set in a range of 50 to 70 according to a reception situation. For example, when the number of received satellites is 4 and the signal strength and SN ratio are small, the evaluation value is set to 50, and when the number of received satellites is 8 and the signal strength and SN ratio is large, the evaluation value is 70. Set to. Considering the degree of distortion of the correlation function of the received signal as the reception status, a small evaluation value can be set when the distortion is large, and a large evaluation value can be set when the distortion is small.

  Also, when communicating with a magnetic nail buried on the road surface or a radio with a predetermined transmission point, the evaluation value is set to 85, and when communicating with a DSRC (for example, an ETC toll gate), Although there is a spread, the vehicle position will not be greatly mistaken within that range, so the evaluation value is set to 75. Note that the above evaluation value is merely an example, and the present invention is not limited to this.

  FIG. 12 is an explanatory view showing a variation example of the evaluation value. When the sensor unit 38 includes a wheel speed sensor and a gyro sensor, the traveling speed of the host vehicle is measured by the wheel speed sensor, and the traveling direction (direction) of the host vehicle is measured by the gyro sensor. In this case, when it can be determined that the host vehicle is stopped, the outputs of the four wheel speed sensors and the gyro sensor are 0. For example, the evaluation value is decreased by 1 every 10 seconds. In addition, when it can be determined that the vehicle travels straight and that there is no tire slip or idling, the outputs of the four wheel speed sensors are almost the same value, the outputs of the gyro sensors are 0, and the evaluation is performed every 10 m. Decrease the value by 1. When the vehicle is traveling in a curve, the output of the outer wheel speed sensor is larger than the inner wheel speed sensor, the output (integrated value) of the gyro sensor is other than 0, and the evaluation value is decreased by 3 every 10 m of traveling. Let Further, when the tire is slipped, the outputs of the four wheel speed sensors vary, and when the true value is unclear, the evaluation value is decreased by 5 to 10 for every 10 m traveling according to the variation.

  As shown in FIG. 12, the evaluation value is set to 90 when the optical beacon passes. By traveling 100 m for 10 seconds, the evaluation value decreases by 10 to 80. Thereafter, the evaluation value is decreased by 1 to 79 by stopping for 10 seconds. Thereafter, the evaluation value decreases by 10 to 69 by traveling 100 m for 10 seconds. Thereafter, the evaluation value decreases by 15 to 54 by traveling 50 m on the curve in 5 seconds. Thereafter, the evaluation value decreases by 15 to 39 by traveling 150 m for 15 seconds. At this time, the GPS signal is received well, and the evaluation value is set to 70. Thereafter, the evaluation value decreases by 30 to 40 by traveling 300 m for 30 seconds. The same variation is repeated thereafter. The range in which the reception time can be corrected is when the evaluation value is 50 or more.

  The sensor unit 38 may include an acceleration sensor and a gyro sensor. In this case, the travel distance and direction of the own vehicle are measured by the acceleration sensor, and the direction of the own vehicle is measured by the gyro sensor. Since the error of the own vehicle position accumulates only with the passage of time, the evaluation value can be reduced by adding the values according to the passage of time and the travel distance. For example, the evaluation value is decreased by 1 every time 1 second elapses, and at the same time, the evaluation value is decreased by 5 every time 10 m is traveled.

  Next, a method for specifying the position of the own vehicle will be described. FIG. 13 is an explanatory view showing an example of the traveling state of the own vehicle, and FIGS. 14 and 15 are flowcharts showing a processing procedure for specifying the position of the own vehicle. As shown in FIG. 13, the vehicle equipped with the vehicle-mounted device 30 measures its own vehicle position in the region R (point R) where the optical beacon 10 is installed, and then corrects the reception time at the point A. Let B identify the position of the vehicle. Hereinafter, a description will be given with reference to FIGS.

  The control unit 33 determines whether or not a positioning signal has been received based on the presence or absence of a signal from the optical beacon 10 (S11). If no positioning signal has been received (NO in S11), the process of step S11 is performed. Repeat and wait until a positioning signal is received.

  When the positioning signal is received (YES in S11), the control unit 33 measures the vehicle position based on the positioning signal (S12), and the reliability of the positioning accuracy according to the positioning method (in this case, the optical beacon 10). The evaluation value (reliability) is set (S13). The control unit 33 measures the travel distance and travel direction (orientation) of the vehicle according to the output of the sensor unit 38 (S14), and evaluates the evaluation value according to the elapsed time, travel distance, and travel direction from the time of positioning. Calculate (S15). The evaluation value will decrease from the set value.

  The control unit 33 determines whether or not a signal has been received from the transmitter 20 (S16). If no signal has been received (NO in S16), the processing from step S14 is continued. When the signal is received (YES in S16), the control unit 33 determines whether or not the evaluation value is greater than or equal to a predetermined threshold (S17). If the evaluation value is smaller than the threshold (NO in S17), step S11 Continue the subsequent processing.

  When the evaluation value is equal to or greater than the predetermined threshold (YES in S17), the control unit 33 specifies the reception point of the signal transmitted by the transmitter 20 (S18). The reception point is, for example, a position obtained by adding a travel distance to the measured own vehicle position, or a position that further considers the travel direction. The control unit 33 acquires transmission time point information and transmission point information of the received signal (S19), and corrects the reception time (S20). The transmission time point information includes a transmission time point, a counter value at the transmission time point, and the like. However, the transmission time point information is not limited to this, and any information can be used as long as the signal transmission time point can be specified. May be. Further, when the valid flag is not turned on in the received signal, the control unit 33 invalidates the signal because the signal is not valid.

  By correcting the reception time, the time of the in-vehicle device 30 and the transmitter 20 is synchronized. Note that the time synchronization means, for example, that the time between the transmitter 20 and the vehicle-mounted device 30 is matched in a pseudo manner, or the relative time between the transmitter 20 and the vehicle-mounted device 30 (for example, , Counter value). In order to synchronize both times, the time of the vehicle-mounted device 30 can be corrected to match the time of the transmitter 20, or the time of the transmitter 20 can be matched with the time of the vehicle-mounted device 30. It can also be corrected.

  The control unit 33 determines whether or not a signal is received from the transmitter 20 (S21). If no signal is received (NO in S21), the control unit 33 determines whether or not a positioning signal is received (S22). . When the positioning signal has not been received (NO in S22), the control unit 33 continues the process after step S21. When the positioning signal is received (YES in S22), the control unit 33 continues the processing after step S12.

  When the signal is received from the transmitter 20 (YES in S21), the control unit 33 calculates the arrival time of the signal based on the transmission time and reception time of the signal (S23), and the calculated arrival time and the transmitter 20 Based on the transmission point information, the vehicle position is specified (S24). For example, the vehicle position can be specified assuming that the distance from the transmitter 20 is L2. Note that if the valid flag is not turned on in the received signal, the control unit 33 invalidates the signal as not valid and does not specify the vehicle position.

  The control unit 33 determines whether or not there is an instruction to end the process (S25). If there is no end instruction (NO in S25), the control unit 33 continues the process after step S21 and continues to specify the vehicle position. If there is an end instruction (YES in S25), the control unit 33 ends the process.

  The vehicle position can be specified by the transmitter 20, but by combining the signal received by the GPS receiving unit 37, the measurement result obtained by the sensor unit 38, road information of the map database 39, etc. It can be specified with high accuracy.

  FIG. 16 is an explanatory diagram showing an example of a method for specifying the vehicle position. In FIG. 16, the case where the communication area | region of the transmitter 20, the vehicle equipment 30, and the optical beacon 10 is not on a straight line is shown. In FIG. 16, it is assumed that the communication area of the optical beacon 10 and the transmission point of the transmitter 20 are known. That is, it is assumed that the communication area of the optical beacon 10 is 150 m upstream in the lane direction and 40 m in the vehicle width direction with respect to the transmitter 20.

  It is assumed that the vehicle-mounted device 30 measures its own vehicle position through communication with the optical beacon 10 and then goes straight 20 m, and then travels 14.1 m at an angle of 45 degrees and changes the lane. As a result, the in-vehicle device 30 assumes that the position of the own vehicle is at the position of the point A. Further, it is assumed that the accuracy of the sensor unit 38 is sufficient in the traveling so far, and the reliability evaluation value of the positioning accuracy exceeds the threshold value.

  When a signal is received from the transmitter 20 at the point A, the in-vehicle device 30 corrects the reception time. In this case, the in-vehicle device 30 calculates and stores a distance (for example, 130 m) between the transmitter 20 and the in-vehicle device 30. When the vehicle continues to travel and then receives a signal from the transmitter 20, the vehicle-mounted device 30 has a signal arrival time shorter than that received at the point A by 200 nanoseconds, that is, the transmitter 20 and the vehicle-mounted Assume that it is determined that the distance to the machine 30 is 60 m shorter. In this case, it can be seen that the vehicle-mounted device 30 exists on a 70-meter sphere centered on the transmitter 20. By combining this information with other information (for example, road shape information, distance information from other transmitters, highly reliable information that can be acquired from the sensor unit 38), the vehicle position can be specified with higher accuracy.

  FIG. 17 is an explanatory diagram showing an example of specifying the vehicle position using road information. As described in the above example, the position of the vehicle can be obtained as the distance L from the transmitter 20 based on the signal transmitted from the transmitter 20. That is, the position of the own vehicle exists on a spherical surface having a distance L with respect to the transmitter 20. Based on the height of the own vehicle on the road, the height of the transmitter 20, and the like, the position of the own vehicle can be obtained as one point on the spherical surface. Further, as shown in FIG. 17, when several roads cross, roads where the distance from the transmitter 20 is L out of roads considered to be traveling by the own vehicle run. The vehicle position can be specified more accurately by using the road information together.

  When synchronizing the time of the vehicle equipment 30 and the time of the transmitter 20, it can also be realized by synchronizing the reference clock signal of the vehicle equipment 30 with the reference clock signal of the transmitter 20. For example, the transmitter 20 and the in-vehicle device 30 are provided with a phase-locked loop (PLL). For example, the in-vehicle device 30 extracts the cycle (or frequency) of the reference clock signal from the signal transmitted from the transmitter 20, and sets the cycle (frequency) of the reference clock signal so as to be the same cycle as the extracted cycle. adjust. Thereby, the timer or clock timed by the transmitter 20 and the timer or clock timed by the in-vehicle device 30 can be synchronized.

Embodiment 2
In the first embodiment, the time between the vehicle-mounted device 30 and the transmitter 20 is simulated when a predetermined signal is received from the transmitter 20 after the position of the vehicle is measured by the optical beacon 10 or the GPS receiver 37 or the like. However, the present invention is not limited to this, and a predetermined signal has been received from the transmitter 20 before the own vehicle position is measured by the optical beacon 10 or the GPS receiver 37 or the like. Even in this case, the time between the in-vehicle device 30 and the transmitter 20 can be artificially synchronized.

  FIG. 18 is an explanatory diagram showing an example of the procedure for specifying the own vehicle position according to the second embodiment. The control unit 33 repeatedly receives a signal (including transmission time information) transmitted by the transmitter 20 at an arbitrary timing through the second communication unit 32. In the example of FIG. 18, the control unit 33 receives a signal whose transmission time is t11 at a position D on the road, and stores information included in the received signal, a reception time, and the like in the storage unit 34. Further, the control unit 33 measures the travel distance (travel distance), travel direction, and the like of the vehicle based on the sensor signal output from the sensor unit 38, and the measurement result (for example, travel history including the passage of time and the position of the vehicle) And the like are stored in the storage unit 34.

  The control unit 33 receives the satellite signal from the GPS satellite at the position E by the GPS receiving unit 37 and measures the position of the host vehicle. That is, when the satellite signal is received at the position E, the position E is measured as the own vehicle position. When the vehicle position is measured, an evaluation value (reliability) indicating the reliability of the positioning accuracy of the vehicle position is set to a predetermined value (for example, 70 in the case of GPS).

  The control unit 33 sets an evaluation value at the time when the vehicle position is measured, and then goes back to the past in the travel history stored in the storage unit 34, and the evaluation value temporarily set according to the travel distance and travel direction of the vehicle Is reduced at a predetermined rate. This is because the evaluation value is high at a point where the vehicle position can be measured, and the evaluation value decreases as the distance from the positioning position goes back in the past. Thereby, the control part 33 can grasp | ascertain the reduction | decrease state of positioning accuracy retroactively from the time of a positioning in consideration of the error accumulate | stored in the own vehicle position according to a travel distance and a travel direction. It should be noted that all or part of the travel time when traveling from position D to position E can be added to the decrease in the evaluation value.

  The control unit 33 determines whether or not the evaluation value at the position D is greater than a predetermined threshold (that is, whether or not the positioning accuracy is sufficiently reliable), and the evaluation value is equal to or greater than the predetermined threshold. If so, the reception time is corrected based on the signal received from the transmitter 20, and if the evaluation value is smaller than the threshold value, the reception time is not corrected because the vehicle position includes an error exceeding the allowable range. In the example of FIG. 18, the reception time is corrected. As a result, when the vehicle position is measured and the signal has already been received from the transmitter 20 before positioning, the reception time can be corrected at the time of reception.

  The correction of the reception time can be performed in the same manner as in the first embodiment as in the examples of FIGS. 7 to 9, and the transmission time information of the signal is acquired from the signal received through the second communication unit 32, This is performed based on the transmission time specified by the acquired transmission time information. In this case, the signal reception point (position D, which serves as a reference position for specifying the vehicle position) is assumed to be the vehicle position by an optical beacon or a GPS receiver before the vehicle reaches position D. Can be determined by the travel distance and travel direction from the measured vehicle position. As a result, the in-vehicle device 30 can artificially synchronize the time at the position D so that it can be determined which time in the in-vehicle device 30 is in the transmitter 20.

  After correcting the reception time at the position D, the control unit 33 repeatedly receives a signal (including transmission time information) transmitted from the transmitter 20 through the second communication unit 32 (for example, time t12,...). . The control unit 33 acquires the transmission time information of the signal from the received signal, and the time difference between the transmission time specified by the acquired transmission time information and the reception time of the signal (that is, the signal is transmitted from the transmitter 20 to the vehicle. The vehicle position (for example, position F,...) Is specified by obtaining the distance to the transmitter 20 based on the arrival time until the vehicle 30 is reached.

  FIG. 19 is an explanatory diagram illustrating an example of reliability evaluation of positioning accuracy according to the second embodiment. FIG. 19 shows the reliability of positioning accuracy and whether or not the reception time can be corrected. As shown in FIG. 19, when position information is acquired from a GPS receiver at position E (or when communication with an optical beacon is performed), an evaluation value indicating reliability of positioning accuracy is set to a predetermined value. Raise (set). The evaluation value to be set can be set to a different value depending on the accuracy of the positioning method.

  The evaluation value is set to a predetermined value at the time when the own vehicle position is measured, and thereafter, the evaluation value is decreased at a predetermined rate according to the passage of time, the traveling distance of the own vehicle, and the traveling direction, Even before the time when the position of the host vehicle is measured, the evaluation value is similarly decreased at a predetermined rate according to the passage of time, the travel distance of the host vehicle, and the travel direction. This is because the evaluation value is highest before and after the positioning time when the vehicle position is measured.

  When a signal is received from the transmitter 20 before the GPS signal is received at the position E and the position of the host vehicle is measured, the evaluation value at the time of reception is a predetermined threshold (for example, 50) or more. If present (signal a12 in FIG. 19), the reception time is corrected. In addition, when a signal is received from the transmitter 20 before the time at which the vehicle position is measured, if the evaluation value at the time of reception is smaller than a predetermined threshold (signal a11 in FIG. 19), the reception time Do not make corrections.

  In the example of FIG. 19, if the evaluation value after receiving the GPS signal at the position E is not used, the evaluation value at the time of receiving any of the signals a11, a12, and a13 transmitted from the transmitter 20 is equal to or less than the threshold value. Therefore, when a signal is transmitted at such a timing, the reception time cannot be corrected, and the vehicle position cannot be specified for a relatively long traveling period. In particular, when a signal cannot be transmitted from the transmitter 20 at an arbitrary timing, there is a possibility that a situation in which a section and a period in which the vehicle position cannot be specified becomes long will appear remarkably. On the other hand, when the evaluation value after receiving the GPS signal at the position E is used, the reception time of the signal a12 transmitted from the transmitter 20 can be captured and the reception time can be corrected. From the time when the vehicle position is performed, the vehicle position can be specified with high accuracy, and the section and period in which the vehicle position can be specified can be expanded.

  As described above, when the positioning accuracy of the host vehicle position is high, the reception time point can be corrected to accurately identify the host vehicle position, and when the positioning accuracy of the host vehicle position is low, the reception time point Thus, it is possible to prevent an erroneous vehicle position from being specified without performing the correction of the above. Further, the reliability can be set according to the positioning accuracy of the positioning method. Further, it is possible to prevent the reception time point from being erroneously corrected due to an error in the vehicle position that occurs according to the moving distance or the elapsed time, and it is possible to maintain a highly reliable correction of the reception time point. Furthermore, even when a signal is received before highly reliable positioning is performed, the reception time can be corrected, and the vehicle position can be specified over a wider period or section. Is possible.

  FIG. 20 is an explanatory diagram showing a variation example of the evaluation value according to the second embodiment. When the sensor unit 38 includes a wheel speed sensor and a gyro sensor, the traveling speed of the host vehicle is measured by the wheel speed sensor, and the traveling direction (direction) of the host vehicle is measured by the gyro sensor. In this case, when it can be determined that the vehicle is stopped, the outputs of the four wheel speed sensors are 0, and the output of the gyro sensor is also 0 when the offset correction is performed. For example, the evaluation value is obtained every time 10 seconds elapse. Is reduced by one. In addition, when it can be determined that the vehicle travels straight and that there is no tire slip or idling, the outputs of the four wheel speed sensors are almost the same value, the outputs of the gyro sensors are 0, and the evaluation is performed every 10 m. Decrease the value by 1. When the vehicle is traveling in a curve, the output of the outer wheel speed sensor is larger than the inner wheel speed sensor, the output (integrated value) of the gyro sensor is other than 0, and the evaluation value is decreased by 3 every 10 m of traveling. Let Further, when the tire is slipped, the outputs of the four wheel speed sensors vary, and when the true value is unclear, the evaluation value is decreased by 5 to 10 for every 10 m traveling according to the variation.

  In addition, the fluctuation | variation of the evaluation value according to the above driving | running | working states can obtain | require the degree of decrease of an evaluation value retroactively by memorize | storing the past driving | running | working state as a driving | running locus | trajectory (running history). .

  As shown in FIG. 20, the evaluation value is set to 70 when the GPS signal is received satisfactorily (at the time of positioning). Since the vehicle traveled 200 m for 20 seconds immediately before receiving the GPS signal, the evaluation value is 50 at a time point 20 seconds before the positioning. Furthermore, since the vehicle traveled on the curve for about 5 seconds immediately before that, the evaluation value decreases according to the travel state.

  The evaluation value is set to 90 at the time when the optical beacon passes, and then the evaluation value decreases according to the traveling distance and traveling time of the vehicle, and the evaluation value before receiving the GPS signal has passed about 35 seconds from the time when the optical beacon has passed. The threshold value is 50 or less at the time, and the reception time cannot be corrected thereafter. However, during the 20 seconds immediately before the GPS signal is received, the evaluation value after receiving the GPS signal is 50 or more, so that the reception time can be corrected. Thereby, the range in which the reception time point can be corrected can be extended not only after the position of the own vehicle position but also before the positioning as well as after the position of the own vehicle position.

  Further, when the position of the vehicle is measured by the optical beacon 10 or the GPS receiving unit 37, the control unit 33 travels before and after the positioning time (for example, when the vehicle is traveling straight or when traveling along a curve). The range in which the time can be corrected can be determined according to the case where the vehicle is stopped. That is, the control unit 33 sets an evaluation value at the time when the vehicle position is measured, and obtains a difference between the set evaluation value and a threshold value. Based on the travel history, the control unit 33 decreases the evaluation value according to the past travel state, and determines a range up to a point (time point) decreased by an amount corresponding to the difference as a time-correctable range. Thereby, a range in which the evaluation value is larger than a predetermined threshold (for example, 50) can be determined regardless of the traveling state of the host vehicle.

  The control unit 33 determines whether or not a signal is received from the transmitter 20 within a distance determined from the measured vehicle position when the own vehicle position is measured. If the signal is received, the control unit 33 receives the signal. The time can also be corrected. Further, when a signal is received a plurality of times from the transmitter 20 within the determined distance, the reception time may be corrected at each reception time, or the reception time may be corrected at a required reception time. Also good.

  In this case, the specific distance (distance range) may be a range in which the evaluation value is considered to be larger than a predetermined threshold (for example, 50) among the distances traveled after the position of the own vehicle is measured, or the own vehicle It may be a range in which the evaluation value is considered to be larger than a predetermined threshold among the distances that have already traveled until the position is determined. Thereby, the range which can correct | amend a reception time point can be extended also before the positioning of the own vehicle position before the position other than the point which measured the own vehicle position.

  Next, a method for specifying the position of the own vehicle will be described. FIG. 21 is an explanatory diagram showing an example of the traveling state of the host vehicle of the second embodiment, and FIGS. 22 and 23 are flowcharts showing a processing procedure for specifying the position of the host vehicle of the second embodiment. As shown in FIG. 21, a vehicle equipped with the vehicle-mounted device 30 receives a signal from the transmitter 20 at a point D, and then receives a GPS signal well at a point E to determine the position of the own vehicle. Based on the signal received from the transmitter 20 at D, the reception time at the point D is corrected. Then, the position of the own vehicle shall be specified at the point F. Hereinafter, a description will be given with reference to FIGS.

  The control unit 33 determines whether or not a positioning signal has been received based on the presence or absence of a signal from a GPS signal or an optical beacon (S31). If no positioning signal has been received (NO in S31), the control unit 33 proceeds to step S31. Repeat the process and wait until a positioning signal is received.

  When the positioning signal is received (YES in S31), the control unit 33 measures the position of the vehicle based on the positioning signal (S32), and according to the output of the sensor unit 38, the traveling distance and traveling direction ( Orientation) is measured (S33), and it is determined whether or not a signal is received from the transmitter 20 (S34).

  For example, when the signal is received from the transmitter 20 at the point D (YES in S34), the control unit 33 records the reception time of the signal (S35) and specifies the reception point of the signal (S36). In addition, until the GPS signal is received at the point E, the reception point D of the signal can be obtained from the own vehicle position measured in the past, the subsequent travel distance, and the travel direction, and the GPS signal is received at the point E. After that, the vehicle position determined by GPS, the previous travel distance, and the travel direction can be obtained. This is because it is more reliable to obtain the reception point D retroactively from the own vehicle position measured by the GPS signal.

  The control unit 33 determines whether or not a positioning signal has been received based on the presence or absence of a signal from a GPS signal or an optical beacon (S37). If no positioning signal has been received (NO in S37), the control unit 33 proceeds to step S33. Repeat the process. When the signal is not received from the transmitter 20 (NO in S34), the control unit 33 performs the process of step S37.

  When the positioning signal is received (YES in S37), the control unit 33 sets the evaluation value to a predetermined value (S38), and calculates the evaluation value of the reception point or reception point of the signal received in step S34. (S39). In this case, the difference between the set evaluation value and the threshold value is obtained, a range in which the time can be corrected is obtained from the past travel history, and it is determined whether or not a signal is received from the transmitter 20 within the range. it can. The control unit 33 determines whether or not the evaluation value is greater than or equal to a predetermined threshold value (S40). If the evaluation value is smaller than the threshold value (NO in S40), the processing after step S31 is continued.

  When the evaluation value is equal to or greater than the predetermined threshold (YES in S40), the control unit 33 acquires transmission time information and transmission point information of the received signal (S41), and corrects the reception time (S42). The transmission time point information includes a transmission time point, a counter value at the transmission time point, and the like. However, the transmission time point information is not limited to this, and any information can be used as long as the signal transmission time point can be specified. May be. Further, when the valid flag is not turned on in the received signal, the control unit 33 invalidates the signal because the signal is not valid.

  By correcting the reception time, the time of the in-vehicle device 30 and the transmitter 20 is synchronized. Note that the time synchronization means, for example, that the time between the transmitter 20 and the vehicle-mounted device 30 is matched in a pseudo manner, or the relative time between the transmitter 20 and the vehicle-mounted device 30 (for example, , Counter value). In order to synchronize both times, the time of the vehicle-mounted device 30 can be corrected to match the time of the transmitter 20, or the time of the transmitter 20 can be matched with the time of the vehicle-mounted device 30. It can also be corrected.

  The control unit 33 determines whether or not a signal is received from the transmitter 20 (S43). If the signal is not received (NO in S43), the control unit 33 determines whether or not a positioning signal is received (S44). . When the positioning signal has not been received (NO in S44), the control unit 33 continues the processing from step S43. When the positioning signal is received (YES in S44), the control unit 33 continues the processing from step S32.

  When the signal is received from the transmitter 20 (YES in S43), the control unit 33 calculates the arrival time of the signal based on the signal transmission time and the reception time (S45), and the calculated arrival time and the transmitter 20 Based on the transmission point information, the vehicle position is specified (S46). For example, the vehicle position can be specified assuming that the distance from the transmitter 20 is L2. Note that if the valid flag is not turned on in the received signal, the control unit 33 invalidates the signal as not valid and does not specify the vehicle position.

  The control unit 33 determines whether or not there is an instruction to end the process (S47). If there is no instruction to end (NO in S47), the control unit 33 continues the process after step S43 and continues to specify the vehicle position. When there is an end instruction (YES in S47), the control unit 33 ends the process.

  In the above example, by measuring the position of the vehicle at the point E, the reception time is corrected by the signal received from the transmitter 20 at the point D before the positioning point, and the point at the point after the positioning point is corrected. Although the vehicle position is specified at the timing when the signal is received from the transmitter 20 in F, the reception time can be corrected at the point D and the vehicle position can be specified.

  FIG. 24 is an explanatory diagram showing an example of correcting the travel history by specifying the own vehicle position. As shown in FIG. 24, it is assumed that the in-vehicle device 30 initially recognizes that the vehicle 30 is traveling along a travel locus along the points D ′ and E ′. For example, the in-vehicle device 30 recognizes that the vehicle position is at the point E by receiving the GPS signal and measuring the vehicle position. Further, assuming that a signal is received from the transmitter 20 at a point D (a point that is traced back from the positioning point E based on the travel locus before correction), the reception time is corrected and the vehicle position is specified at the point D. It can be seen that the vehicle position has passed through point D instead of point D ′. As a result, it becomes clear that the traveling locus of the host vehicle is correctly along the points D and E, and it becomes possible to correct the past traveling locus.

  In the example of FIG. 24, the travel trajectory straddling two roads has been described, but it can also be used to correctly recognize the lane in which a vehicle traveling on a road having a plurality of lanes is traveling. .

  As described above, in the present invention, the transmitter may not be able to transmit a signal at an arbitrary timing, and when the own vehicle is present in the communication area with the optical beacon, Even if the signal cannot be received, the concept of reliability of the positioning accuracy of the vehicle position is introduced, and when it is determined that this reliability is high when the signal is received from the transmitter, By correcting the reception time of the vehicle, the time can be artificially synchronized between the in-vehicle device and the transmitter, and using the corrected reception time, the position of the vehicle can be accurately determined simply by receiving a signal from the transmitter. In particular, the position of the vehicle traveling on the road can be tracked with high accuracy. In particular, it is possible to specify the position of the own vehicle only by providing one transmitter, and it is not necessary to use two or more transmitters, and an inexpensive vehicle position specifying system can be realized.

  Further, in the present invention, the range in which the reception time can be corrected is extended beyond the position where the own vehicle position is measured, that is, after positioning of the own vehicle position or before positioning of the own vehicle position. be able to. In addition, when the positioning accuracy of the vehicle position is high, the reception time point can be corrected to accurately identify the vehicle position, and when the positioning accuracy of the vehicle position is low, the reception time point correction is performed. It is possible to prevent an erroneous vehicle position from being specified without performing the operation. Further, the reliability can be set according to the positioning accuracy of the positioning method. Furthermore, it is possible to prevent a vehicle position from being erroneously specified by receiving a signal that is not an original positioning signal.

  In the above-described embodiment, the transmitter 20 modulates and transmits a signal, and the in-vehicle device 30 demodulates and extracts the original signal, and calculates the reception time of the signal, but is not limited thereto. Instead, the transmitter 20 assigns signals to carriers having different frequencies in the orthogonal frequency multiplexing system, and transmits the carrier to which the signals are assigned. For example, the signal to be transmitted is inverse Fourier transformed 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 transmitter 20 to the in-vehicle device 30. The in-vehicle device 30 performs AD conversion on the transmitted carrier wave, and acquires a signal reception time point 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, a configuration using one transmitter is used, but a configuration using two or more transmitters may be used. For example, by using three transmitters, the vehicle position can be specified as an intersection of three spherical surfaces having the same distance from each transmitter.

  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 through the intersection, and the driver is alerted by voice according to the determination result. be able to. In addition, it is possible to determine with high accuracy whether or not the vehicle can safely pass through the intersection based on the display information of the traffic signal received by the vehicle-mounted device, and to perform vehicle brake control according to the determination result. Accidents can be prevented and traffic safety can be improved.

Embodiment 3
FIG. 25 is a block diagram showing a configuration of a time correction system according to the present invention. The time correction system according to the present invention can be used to correct the reception time in the vehicle position specifying system described in the first and second embodiments. The time correction system includes a transmitter 20, a time correction device 40, and the like. The transmitter 20 is the same as that in the first and second embodiments, and thus the description thereof is omitted. Further, the difference between the time correction device 40 and the in-vehicle device 30 is that the time correction device 40 does not have the first communication unit 31 and the sensor unit 38 of the in-vehicle device 30 and has the same function as the second communication unit 32. The communication unit 42 is provided. In addition, the structure provided with the 1st communication part 31 and the sensor part 38 may be sufficient.

  The time correction device 40 measures its own position with the GPS receiving unit 43 and can use the map database 47 together to obtain its own moving distance, moving direction, moving history, and the like. Note that the control unit 41, the storage unit 44, the display unit 45, and the operation unit 46 are the same as those in the first and second embodiments, and thus description thereof is omitted.

  Similar to the vehicle-mounted device 30 of the first and second embodiments, the time correction device 40 receives the transmission time point information specifying the signal transmission time point from the transmitter 20, and receives the received transmission time point information and the transmission time point information. The time is corrected based on the received reception point and transmission point information (position information of the transmitter 20). In this case, even if there is a time zone in which the transmitter 20 cannot transmit a signal and the signal cannot be arbitrarily transmitted, the time correction device 40 can correct the time.

  The time correction device 40 is mounted on a vehicle as an in-vehicle device, so that the position of the vehicle can be accurately identified using the result of time correction. In addition, by making the time correction device 40 portable, it is possible to perform time correction for specifying the position of not only the vehicle but also other moving bodies such as pedestrians. Note that the position of the moving object may be specified using the result of time correction, or may be used for other purposes.

  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 vehicle location specification system which concerns on this invention. It is a block diagram which shows the structure of the vehicle location specification 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 the data structure contained in the signal which a transmitter transmits. It is explanatory drawing which shows the example which calculates | requires the reception time of a signal. It is explanatory drawing which shows the example of the specific procedure of the own vehicle position. It is explanatory drawing which shows an example of correction | amendment at the time of signal reception. It is explanatory drawing which shows the other example of correction | amendment of the reception time of a signal. It is explanatory drawing which shows the other example of correction | amendment of the reception time of a signal. It is explanatory drawing which shows the example of reliability evaluation of positioning accuracy. It is explanatory drawing which shows the numerical example of an evaluation value. It is explanatory drawing which shows the example of a fluctuation | variation of an evaluation value. It is explanatory drawing which shows the example of the driving | running | working state of the own vehicle. It is a flowchart which shows the process sequence which pinpoints the position of the own vehicle. It is a flowchart which shows the process sequence which pinpoints the position of the own vehicle. It is explanatory drawing which shows an example of the identification method of the own vehicle position. It is explanatory drawing which shows the example which pinpoints the own vehicle position using road information. FIG. 10 is an explanatory diagram illustrating an example of a procedure for specifying the position of the host vehicle according to the second embodiment. 10 is an explanatory diagram illustrating an example of reliability evaluation of positioning accuracy according to Embodiment 2. FIG. FIG. 10 is an explanatory diagram showing an example of variation in evaluation value according to the second embodiment. It is explanatory drawing which shows the example of the driving state of the own vehicle of Embodiment 2. FIG. 10 is a flowchart showing a processing procedure for specifying the position of the host vehicle in the second embodiment. 10 is a flowchart showing a processing procedure for specifying the position of the host vehicle in the second embodiment. It is explanatory drawing which shows the example which corrects a driving | running | working history by specification of the own vehicle position. It is a block diagram which shows the structure of the time correction system which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical beacon 20 Transmitter 21 Communication part 22 Control part 30 Car-mounted apparatus 31 1st communication part 32 2nd communication part 33 Control part 34 Memory | storage part 35 Display part 36 Operation part 37 GPS receiving part 38 Sensor part 39 Map database 40 Time correction Device 41 Control unit 42 Communication unit 43 GPS reception unit 44 Storage unit 45 Display unit 46 Operation unit 47 Map database

Claims (28)

In a vehicle location system including a transmitter that transmits a predetermined signal and an in-vehicle device that receives a signal transmitted by the transmitter,
The in-vehicle device is
Receiving means for receiving transmission time information for specifying a signal transmission time;
Storage means for storing transmission point information for identifying a signal transmission point;
Transmission time information received by the reception means, reception point that received the transmission time information, and reception time correction means that corrects the reception time of the signal based on the transmission point information;
Specifying means for specifying the vehicle position based on the transmission time information of the signal, the transmission point information, and the reception time of the signal corrected by the reception time correction means when receiving a signal from the transmitter; A vehicle location system characterized by that. The in-vehicle device is
Equipped with positioning means for positioning the vehicle position,
The reception time correction means includes:
When positioning the vehicle position by the positioning means, based on the transmission time information received by the receiving means before or after positioning, the reception point that received the transmission time information and the transmission point information, The vehicle position specifying system according to claim 1, wherein the vehicle position specifying system is configured to correct. The in-vehicle device is
Measuring means for measuring the travel distance and / or travel direction of the vehicle;
Receiving point specifying means for specifying the receiving point of the transmission time information based on the measured vehicle position and the result measured by the measuring means when receiving the transmission time information by the receiving means, The vehicle position specifying system according to claim 2. The in-vehicle device is
A determination unit for determining the reliability of the vehicle position measured by the positioning unit and / or the reliability of the reception point specified by the reception point specifying unit;
The reception time correction means includes:
4. The vehicle position specifying system according to claim 2, wherein when the reliability determined by the determination unit is greater than a predetermined threshold, the reception time of the signal is corrected. 5. The in-vehicle device is
When the vehicle position is measured by the positioning means, a reception point determination means for determining whether there is a reception point specified by the reception point specification means within a specific distance from the measured vehicle position,
The reception time correction means includes:
The vehicle position specifying system according to claim 2 or 3, wherein when the reception point determination unit determines that there is a reception point, the reception point of the signal is corrected. The in-vehicle device is
6. The vehicle position specifying system according to claim 5, further comprising a determining unit that determines the specific distance according to a traveling state of the host vehicle. The in-vehicle device is
The vehicle position specifying system according to any one of claims 2 to 6, further comprising setting means for setting reliability of the own vehicle position when the own vehicle position is measured by the positioning means. The in-vehicle device is
Provided with detecting means for detecting whether or not the vehicle has passed a predetermined point,
The positioning means includes
When detected by the detection means, it is configured to measure the position of the vehicle,
The setting means includes
8. The vehicle position specifying system according to claim 7, wherein the reliability of the own vehicle position is set to a predetermined value. The in-vehicle device is
Comprising satellite signal receiving means for receiving a satellite signal transmitted by a GNSS satellite;
The positioning means includes
When the satellite signal is received by the satellite signal receiving means, the vehicle position is determined,
The setting means includes
8. The vehicle position specifying system according to claim 7, wherein a reliability of the own vehicle position is set in accordance with a reception status of the satellite signal received by the satellite signal receiving means. The in-vehicle device is
10. The apparatus according to claim 2, further comprising a reducing unit that decreases the reliability set by the setting unit in accordance with a moving distance of the host vehicle after the vehicle position is measured by the positioning unit. The vehicle position specifying system according to claim 1. The in-vehicle device is
10. The apparatus according to claim 2, further comprising a reducing unit that decreases the reliability set by the setting unit according to a lapse of time after the vehicle position is measured by the positioning unit. Vehicle positioning system described in 1. The in-vehicle device is
When the vehicle position is measured by the positioning means, the reliability of the reception point is set according to the movement distance between the measured vehicle position and the reception point specified by the reception point specifying means before positioning. The vehicle position specifying system according to any one of claims 2 to 9, further comprising a reducing unit that reduces the reliability set by the unit. The in-vehicle device is
When the vehicle position is measured by the positioning means, the reception is performed according to the passage of time between the positioning time of the vehicle position and the reception time of the signal at the receiving point specified by the receiving point specifying means before positioning. The vehicle position specifying system according to any one of claims 2 to 9, further comprising a reducing unit that reduces the reliability of the point from the reliability set by the setting unit. The in-vehicle device is
An acquisition means for acquiring information for specifying a signal propagation time between a reception point at which transmission time information is received by the reception means and a transmission point of the transmission time information;
The reception time correction means includes:
The signal reception time point is corrected based on a value obtained by adding the signal propagation time to the transmission time point specified by the transmission time point information. The vehicle position specifying system according to claim 1. The in-vehicle device and the transmitter are:
With timekeeping means,
The reception time correction means includes:
The time of reception corresponding to the transmission time specified by the transmission time information is used as the time of measurement corresponding to the time of reception of the signal whose transmission time is specified by the transmission time information. The vehicle position specifying system according to any one of claims 1 to 13, wherein The in-vehicle device is
Generating means for generating a reference period signal of a predetermined period;
Clocking means for timing based on the reference periodic signal generated by the generating means;
A reception point that has received the transmission time information by the reception means, a transmission time point specified by the transmission time information, and a period correction means for correcting the period of the reference periodic signal based on the transmission point information,
The reception time correction means includes:
The signal reception time point is corrected based on a time value measured by the reference period signal corrected by the period correction means. Vehicle positioning system described in 1. The in-vehicle device is
Transmission point correction means for correcting the transmission point specified by the transmission point information based on the reception point that received the transmission point information by the reception unit, the transmission point specified by the transmission point information, and the transmission point information The vehicle position specifying system according to any one of claims 1 to 3, further comprising: It has multiple transmitters that transmit transmission time information,
The specifying means is:
18. The vehicle position according to claim 1, wherein the vehicle position is specified based on a transmission time specified by the transmission time information and a reception time of a signal transmitted by each transmitter. The vehicle position specifying system according to any one of the above. The in-vehicle device is
A road information acquisition means for acquiring road information;
The specifying means is:
The vehicle position specifying system according to any one of claims 1 to 18, wherein the vehicle position is specified based on road information acquired by the road information acquiring means. The transmitter is
The signal to be transmitted is configured to be transmitted including information indicating that the signal is valid,
The specifying means is:
The vehicle position specifying system according to any one of claims 1 to 19, wherein the vehicle position is specified when the received signal includes the information. In an in-vehicle device that receives a predetermined signal,
Receiving means for receiving transmission time information for specifying a signal transmission time;
Storage means for storing transmission point information for identifying a signal transmission point;
Transmission time information received by the reception means, reception point that received the transmission time information, and reception time correction means that corrects the reception time of the signal based on the transmission point information;
And a specifying means for specifying the vehicle position based on the transmission time information of the signal, the transmission point information, and the reception time of the signal corrected by the reception time correction means when receiving a signal. In-vehicle machine. In a transmitter that transmits a predetermined signal,
A transmitter comprising: transmission means for transmitting transmission time information for specifying a transmission time of a signal. A time correction system comprising a transmitter that transmits a predetermined signal and a time correction device that receives the signal transmitted by the transmitter and corrects the time,
The time correction device is:
Receiving means for receiving transmission time information for specifying a signal transmission time;
Storage means for storing transmission point information for identifying a signal transmission point;
A time correction system comprising: transmission time information received by the reception means, a reception point that has received the transmission time information, and time correction means for correcting time based on the transmission point information. The time correction device is
It has positioning means to measure its own position,
The time correction means includes
When the positioning means measures its own position, the time is corrected based on the transmission time information received by the reception means before or after positioning, the reception point that received the transmission time information, and the transmission point information. The time correction system according to claim 23, wherein the time correction system is configured as follows. The time correction device is:
A measuring means for measuring its own moving distance and / or moving direction;
Receiving point specifying means for specifying the receiving point of the transmission time information based on the position of the positioning itself and the result measured by the measuring means when receiving the transmission time information by the receiving means, The time correction system according to claim 24. The time correction device is:
A determination means for determining the reliability of the position measured by the positioning means and / or the reliability of the reception point specified by the reception point specification means;
The time correction means includes
The time correction system according to claim 24 or 25, wherein the time is corrected when the reliability determined by the determination means is greater than a predetermined threshold. The time correction device is:
The time correction system according to any one of claims 24 to 26, further comprising setting means for setting a reliability of the position when the position is measured by the positioning means. A time correction device for correcting a time by receiving a predetermined signal,
Receiving means for receiving transmission time information for specifying a signal transmission time;
Storage means for storing transmission point information for identifying a signal transmission point;
A time correction apparatus comprising: transmission time information received by the reception means, a reception point where the transmission time information is received, and time correction means for correcting time based on the transmission point information.

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