JP4661852B2 - Vehicle location system - Google Patents

Description

The present invention relates the position of the vehicle traveling on the road to the vehicle position specifying system that can be identified with high accuracy.

Conventionally, in order to prevent traffic accidents between vehicles in and around the intersection or between vehicles and pedestrians, display information on the light color of traffic lights 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 the vehicle can safely pass through the intersection based on the display information of the traffic signal received by the in-vehicle device, and performs brake control of the vehicle according to the determination result is 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 an object thereof is to provide a vehicle position specifying system that can accurately identify the position of the vehicle.

A vehicle position specifying system according to a first aspect of the present invention includes a transmitter installed at a predetermined point and transmitting a predetermined signal, and an in-vehicle device that receives a signal transmitted from the transmitter and specifies a position. In the system, the in-vehicle device acquires road shape information related to a road shape, storage means for storing transmission point information of the transmitter, arrival time acquisition means for acquiring the arrival time of a signal transmitted by the transmitter, and and the road shape information obtaining means, the transmission point information, based on the arrival time and the road shape information, comprising: a specifying unit that specifies the vehicle position, and storage means for storing the height information of the mounting position, said specifying means Specifies the intersection line between the virtual traveling surface of the vehicle determined by the road shape information and the height information and the virtual spherical surface determined by the transmission point information and the arrival time as the vehicle position. Configured characterized tare Rukoto.

According to a second aspect of the present invention, in the first aspect , the vehicle-mounted device includes a region information acquisition unit that acquires region information indicating a region where the host vehicle is present, and the identification unit includes the region information. The present invention is characterized in that an intersection line between the traveling surface and the phantom spherical surface within the existing region indicated by the region information acquired by the acquiring unit is specified as the vehicle position.

In the vehicle position specifying system according to a third aspect of the present invention, in the second aspect , the area information is information related to the vehicle position acquired by a car navigation system or a GPS receiver, or information related to a communication point with the roadside device. And

According to a fourth aspect of the present invention, in the second aspect , the in-vehicle device includes a storage unit that stores the travel history information of the host vehicle, and the region information acquisition unit is configured to determine the vehicle position from the most recently specified host vehicle position. The region information is obtained based on the traveling history information.

According to a fifth aspect of the present invention, in the fourth aspect , the travel history information includes at least one of travel distance, travel speed, acceleration / deceleration, or travel direction information.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the transmitter includes transmission means for transmitting transmission time information for specifying a signal transmission time, and The time acquisition means is configured to acquire the arrival time of the signal based on the reception time of the signal and the transmission time of the signal.

In the first shot bright, vehicle-mounted device, if the transmitter has received the transmitted signal to obtain a signal arrival time. The arrival time of the signal can be obtained from the time difference between the signal transmission time and the signal reception time. Further, the transmission time point information regarding the signal transmission time point can be included in the signal to be transmitted. The in-vehicle device acquires road shape information related to the road shape. The road shape information includes, for example, information such as distance, gradient, or curvature for each section obtained by dividing the road into one or a plurality of appropriate length sections. The vehicle-mounted device identifies the vehicle position based on transmission point information of the transmitter (for example, absolute position information including height or relative position information), arrival time of the received signal, and road shape information. For example, according to the transmission point information of the transmitter and the arrival time of the signal, the vehicle position is on a spherical surface centered on the position of the transmitter and having a radius corresponding to the arrival time. By combining this with the road shape information of the road on which the host vehicle is traveling, the host vehicle position can be specified. Thereby, even if it does not use a some transmitter, the position of a vehicle can be pinpointed by installing one transmitter.

Further , the in-vehicle device specifies a virtual traveling surface of the own vehicle determined by the road shape information and the height information of the in-vehicle device. The in-vehicle device specifies an intersection line between the specified traveling surface and a virtual spherical surface having a radius corresponding to the arrival time centered on the position of the transmitter as the own vehicle position. Thereby, even if it does not use a some transmitter, the position of a vehicle can be pinpointed with high precision by installing one transmitter.

In the second invention, the in-vehicle device acquires area information indicating an existing area where the host vehicle is present. The vehicle-mounted device specifies the intersection line between the traveling surface and the virtual spherical surface in the vehicle presence region indicated by the acquired region information as the vehicle position. As a result, even if there are two intersection lines between the traveling surface and the virtual spherical surface, the intersection line in the vehicle's existence area can be specified as the vehicle position, and a plurality of transmitters can be specified. Even if it is not used, the position of the vehicle can be specified with high accuracy by installing one transmitter.

In the third invention, the in-vehicle device is positioned by receiving the information on the vehicle position output from the car navigation system, the information on the communication point with the roadside device such as an optical beacon, or the GPS satellite signal. Area information indicating the existence area of the own vehicle is acquired from the information of the own vehicle position. As a result, the area where the vehicle is present can be narrowed down, and the traveling surface can be specified in a narrower range, so that the vehicle position can be specified with high accuracy.

In the fourth aspect of the invention, the in-vehicle device acquires region information indicating the presence region of the own vehicle based on the travel history information from the most recently specified own vehicle position. As a result, once the vehicle position can be specified, the vehicle position can be obtained by installing one transmitter without using a plurality of transmitters by using the subsequent travel history. Can be specified with high accuracy.

In the fifth invention, the travel history information includes at least one of travel distance, travel speed, acceleration / deceleration, or travel direction information. Combining these information with road shape information and vehicle-mounted device height information makes it possible to narrow down the existence area of the vehicle, that is, the range of the traveling surface of the vehicle, and the vehicle position can be accurately identified. .

In the sixth aspect of the invention, the in-vehicle device acquires transmission time information specifying the signal transmission time from the signal transmitted by the transmitter, and based on the signal reception time and the signal transmission time, Get the arrival time. Thereby, the vehicle-mounted device can specify that the vehicle is on a spherical surface having the same distance corresponding to the arrival time with the transmitter as the center.

  In the present invention, the position of the vehicle can be accurately identified by installing one transmitter without using a plurality of transmitters. 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 includes a transmitter 20 installed at a predetermined position and transmitting a predetermined signal, an in-vehicle device 30 mounted on the vehicle, and the like. When the vehicle travels toward the stop line, the in-vehicle device 30 receives the signal transmitted from the transmitter 20 and identifies the vehicle position based on the arrival time of the received signal. When the transmitter 20 repeatedly transmits the signal, the in-vehicle device 30 can specify the vehicle position every time the signal is received. Details of the method for specifying the vehicle position will be described later.

  FIG. 2 is a block diagram showing the configuration of the vehicle position specifying system according to the present invention. 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 repeatedly transmits a predetermined signal to the in-vehicle device 30. The timing at which the transmitter 20 transmits a signal can be arbitrarily set. In addition, the communication time when the in-vehicle device 30 communicates with a roadside device such as an optical beacon, a radio beacon, or a DSRC (Dedicated Short Range Communication) installed near a road is acquired from the roadside device side, and a signal is transmitted at that timing. Can be sent. Further, when there is a time zone in which the signal cannot be transmitted based on a predetermined specification, the transmitter 20 repeatedly transmits the signal to the in-vehicle device 30 at a predetermined timing in the time zone in which transmission is possible.

  The in-vehicle device 30 controls the operation of the first communication unit 31 having a communication function with roadside devices such as an optical beacon, a radio wave beacon, DSRC, the second communication unit 32 having a communication function with the transmitter 20, and the operation of the in-vehicle device 30. A control unit 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 an in-vehicle sensor such as a wheel speed sensor, a gyro sensor, and an acceleration sensor. A navigation unit 39 and the like.

  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 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. 3 is an explanatory diagram illustrating an example of a data structure included in a signal transmitted by the transmitter 20. As shown in FIG. 3, the signal transmitted by the transmitter 20 is, for example, a positioning signal (vehicle position specifying signal) for specifying the vehicle position based on the radio wave from the transmitter 20 and a data area. In the data area, a valid flag indicating that the signal is valid, transmission time information specifying the signal transmission time (for example, time format information timed by the transmitter 20, or counting at a predetermined time interval) Information such as a counter value of a counter to be executed). Note that the positioning signal and data may be transmitted at the same time or different times.

  FIG. 4 is an explanatory diagram illustrating an example of obtaining a signal reception time point. The upper part of FIG. 4A 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. 4A, 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 match, both of the signals as shown in FIG. The correlation value of the signal shows a sharp peak. As shown in FIG. 4B, the second communication unit 32 obtains the signal reception time when the correlation value has a sharp peak. 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.

  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 receiving function such as DGPS (differential GPS) or RTK-GPS (Real-Time Kinematic GPS), and repeatedly receives radio waves from a GNSS (Global Navigation Satellite System) satellite including a plurality of GPSs as needed. Measure the vehicle position. Thereby, the vehicle equipment 30 can acquire the area | region information which shows in which range the own vehicle exists. In addition, the presence area of the own vehicle may fluctuate according to the accuracy of the GPS receiving unit 37, the situation of received radio waves, and the like.

  The navigation unit 39 has a built-in map database and the like, and based on information from the GPS receiving unit 37 and information from the sensor unit 38, a travel history of the vehicle (for example, travel distance, travel direction, travel recorded with time) Speed, acceleration / deceleration, etc.).

  The storage unit 34 stores information received through the first communication unit 31 and the second communication unit 32. For example, the received information includes position information (transmission point information) of the transmitter 20 and a transmitter 40 described later, road shape information regarding the road shape, a reception time when a signal is received from the transmitter 20, and a transmission time of the signal. Transmission time information indicating the position, position information of the roadside device such as an optical beacon (position information of the communication point), and the like. In addition, the storage unit 34 stores height information of the mounting position of the in-vehicle device 30 in advance.

  FIG. 5 is an explanatory diagram showing an example of specifying the vehicle position. When a vehicle equipped with the vehicle-mounted device 30 is traveling on the road, the control unit 33 grasps a rough existence area of the own vehicle from time to time based on information output from the GPS receiving unit 37, the navigation unit 39, and the like. Note that the grasped existence area has two intersection lines between a spherical surface centered on the position of the transmitter 20 and a virtual traveling surface of the own vehicle, as will be described later, when specifying the own vehicle position. This can be used to determine which intersection line to select as the vehicle position. When a signal (positioning signal) is received from the transmitter 20 at a certain point P1 on the road, the control unit 33 determines that the signal is transmitted from the transmitter 20 to the in-vehicle device depending on the difference between the signal reception time and the transmission time. The arrival time until reaching 30 is calculated. In this case, the signal transmission time can be obtained from the transmission time information included in the signal.

  The controller 33 calculates the distance L1 from the transmitter 20 by integrating the speed of light with the arrival time of the signal. That is, it can be seen that the position of the point P1 is on the spherical surface Q1 having the radius L1 with the position of the transmitter 20 as the center.

  On the other hand, when the control unit 33 receives a signal from the transmitter 20 and obtains a position from the transmitter 20, the control unit 33 obtains the road shape information of the road (link: the road between intersections) on which the host vehicle travels and Based on the information, the virtual running surface of the own vehicle is specified. When the road is a straight road, the virtual traveling surface is a plane, and when the road is curved, the virtual traveling surface is a curved surface.

  The control unit 33 specifies the vehicle position as an intersection line intersecting the spherical surface Q1 and the traveling surface. As shown in the example of FIG. 1, when the transmitter 20 is installed near an intersection and the road shape information is given for each link, the center point of the spherical surface Q1 is at the end of the link, so the spherical surface Q1 And the specified traveling surface usually intersect at one intersection line. As a result, it is possible to accurately identify the position of the host vehicle only by receiving a signal from one transmitter 20. In FIG. 5, the point P1 is indicated by a cross, but more precisely, since it is an intersection line where the traveling surface and the spherical surface Q1 intersect, the length is approximately equal to the length of the traveling surface in the road width direction. There is a range of minutes. However, in practice, the vehicle is considered to travel substantially in the middle of the lane or road, and therefore, the position of the approximate center in the width direction of the traveling surface may be specified as the position of the own vehicle.

  Assuming that the vehicle continues to travel and receives a signal from the transmitter 20 at the point P2 on the road, the control unit 33 adds the speed of light to the arrival time of the signal as in the case of the point P1, thereby transmitting the signal. The distance L2 from the machine 20 is calculated. That is, it can be seen that the position of the point P2 is on the spherical surface Q2 having the radius L2 with the position of the transmitter 20 as the center.

  On the other hand, when the control unit 33 receives a signal from the transmitter 20 and obtains a position from the transmitter 20, the control unit 33 uses the road shape information of the road on which the host vehicle travels and the height information of the vehicle-mounted device 30 to determine the virtual vehicle. Specific driving surface.

  The control unit 33 specifies the vehicle position as an intersection line intersecting the spherical surface Q2 and the traveling surface. Thereafter, by repeating the same operation, the control unit 33 can continue to specify the vehicle position with high accuracy each time a signal is received from the transmitter 20.

  FIG. 6 is an explanatory diagram showing the concept of the method for specifying the vehicle position when one transmitter is used. The example of FIG. 6 shows a specifying method when the arrival time of a signal from one transmitter is known. As shown in FIG. 6, first, the vehicle position exists on a spherical surface Q having a radius that is a distance obtained by integrating the speed of light (or the propagation speed of radio waves) with the arrival time of a signal from the transmitter 20 to the vehicle-mounted device 30. . Next, where on the spherical surface Q the vehicle position exists is determined.

  The in-vehicle device 30 specifies the virtual traveling surface S of the own vehicle from the road shape information of the road on which the own vehicle is traveling and the height information of the in-vehicle device 30.

  FIG. 7 is an explanatory diagram showing the structure of road shape information. As shown in FIG. 7, the road shape information is configured by dividing a road into sections of a predetermined distance (for example, 20 m) by a plurality of nodes, and information such as distance, gradient, and curvature for each section. When the road is a straight line, nodes are set on one straight line along the road, and when the road is a curve, nodes (for example, two nodes) are set on a plurality of straight lines along the road. Thereby, even when the road is inclined by the curve, the plane determined by the two straight lines can be specified.

  The control unit 33 can specify an intersection line where the spherical surface Q and the virtual traveling surface S intersect as the own vehicle position. The traveling surface S specified by the road shape information has a belt-like shape and the width is equal to or less than the road width, and the vehicle position can be accurately obtained by specifying the intersection line. In addition, the shape of the running surface S is not limited to a belt shape.

  As shown in FIG. 6, when two intersecting lines where the spherical surface Q and the traveling surface S intersect are specified, the vehicle position can be specified as follows. That is, there are two intersecting lines between the spherical surface Q and the traveling surface S. One of these is information that does not have high accuracy, such as the previous positioning result, the subsequent traveling history, and the positioning result with the GPS receiver. However, it can be determined sufficiently.

  The control unit 33 is information on the vehicle position obtained from a signal received by the GPS reception unit 37, information on the vehicle position output from the navigation unit 39, or information on a communication point with a roadside device such as an optical beacon. Thus, the existence area of the own vehicle can be narrowed down. For example, an own vehicle position (positioning point) obtained by receiving a GPS satellite signal and a region within a predetermined position error centered on the positioning point (for example, a region having a radius of 10 m centered on the positioning point). Narrow down as the existence area of the own vehicle. The intersection line in the narrowed down existence area can be specified as the vehicle position.

  As another method, the control unit 33 can narrow down the existence area of the own vehicle based on the most recently identified own vehicle position and the travel history from that point. For example, when the vehicle has traveled 100 m from the most recently specified vehicle position, an area within a position error associated with travel centered on the predicted travel point after 100 m travel (for example, a region with a radius of 10 m centered on the predicted travel point). Narrow down as the existence area of the own vehicle. The intersection line in the narrowed down existence area can be specified as the vehicle position. In addition, the position error accompanying traveling can be changed according to the reliability of the autonomous sensor such as the wheel speed.

  FIG. 8 is an explanatory diagram showing another example of specifying the vehicle position. In the example of FIG. 5, the vehicle travels while grasping the rough position of the vehicle based on information from the GPS, the navigation system, etc., and when the signal is received from the transmitter 20, it is roughly based on the road shape information. The vehicle position is accurately identified from the correct position. In the example of FIG. 8, the vehicle position is accurately identified at a certain point, and when a signal is received from the transmitter 20, The vehicle position is specified based on the travel history and road shape information.

  As shown in FIG. 8, when the vehicle on which the vehicle-mounted device 30 is mounted is traveling on the road, the control unit 33 specifies the communication point (point R) as the own vehicle position by communication with the optical beacon 10. . Or you may identify the own vehicle position (specification of the nearest own vehicle position) by the point R by the method shown in FIG.

  When a signal (positioning signal) is received from the transmitter 20 at a certain point P3 on the road, the control unit 33 determines that the signal is transmitted from the transmitter 20 to the in-vehicle device due to the difference between the signal reception time and the transmission time. The arrival time until reaching 30 is calculated. In this case, the signal transmission time can be obtained from the transmission time information included in the signal.

  The controller 33 calculates the distance L3 from the transmitter 20 by integrating the speed of light with the arrival time of the signal. That is, it can be seen that the position of the point P3 is on the spherical surface Q3 having the radius L3 with the position of the transmitter 20 as the center.

  On the other hand, when the control unit 33 receives a signal from the transmitter 20 and obtains a position from the transmitter 20, the control unit 33 uses the road shape information of the road on which the host vehicle travels and the height information of the vehicle-mounted device 30 to determine the virtual vehicle. Specific driving surface.

  The control unit 33 identifies the virtual traveling surface of the host vehicle based on the road shape information of the road on which the host vehicle travels (link: a road between intersections) and the height information of the in-vehicle device 30, and the identified traveling surface. And the intersection line of the spherical surface Q3 is specified as the vehicle position. As a result, it is possible to accurately identify the position of the host vehicle only by receiving a signal from one transmitter 20. As shown in the example of FIG. 1, when the transmitter 20 is installed near an intersection and road shape information is given for each link, the center point of the spherical surface Q3 is at the end of the link, so that the spherical surface Q3 And the specified traveling surface usually intersect at one intersection line. For this reason, it is considered that there are very few situations where two intersecting lines intersecting the spherical surface Q3 and the traveling surface are specified. However, when two temporary intersection lines are specified, one intersection line can be selected based on the travel history as described above.

  In the above-described example, when the arrival time of the signal is calculated, it has been described that the time of the in-vehicle device 30 and the transmitter 20 is the same. If the time between the in-vehicle device 30 and the transmitter 20 is not accurately synchronized and an error occurs in the calculated arrival time, the time (clock) between the in-vehicle device 30 and the transmitter 20 is as follows. Can be synchronized.

  FIG. 9 is an explanatory diagram showing an example of correction at the time of signal reception. As illustrated in FIG. 9, for example, it is assumed that the transmitter 20 transmits a signal at time t1. 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 can be obtained from the transmission point of the transmitter 20 and the reception point of the signal transmitted at time t1. The reception point of the signal transmitted at time t1 can be, for example, a communication point with an optical beacon. In this case, the optical beacon notifies the transmitter 20 of the passage of the in-vehicle device 30, and the transmitter 20 may transmit a signal to the in-vehicle device 30 when receiving the notification.

  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. By integrating the speed of light (or the propagation speed of radio waves) with ΔT, the distance from the transmitter 20 to the in-vehicle device 30 can be obtained with high accuracy.

  Next, the operation of the in-vehicle device 30 will be described. FIG. 10 is a flowchart showing a processing procedure for specifying the position of the own vehicle. The control unit 33 acquires area information indicating a range in which it can be estimated that the vehicle is present from a GPS, a navigation system, or the like (S11). The control unit 33 determines whether or not a signal has been received from the transmitter 20 (S12). If the signal has not been received (NO in S12), the processing from step S11 is continued. As a result, the vehicle continues to travel while estimating (measuring) the range in which the vehicle exists.

  When a signal is received from the transmitter 20 (YES in S12), the control unit 33 acquires road shape information and height information of the in-vehicle device 30 (S13), and specifies a virtual traveling surface of the own vehicle ( S14). Based on the received signal, the control unit 33 calculates the arrival time of the signal from the transmitter 20 to the vehicle-mounted device 30 (S15), and based on the distance obtained by adding the speed of light to the calculated arrival time. Then, a spherical surface centered on the position of the transmitter 20 is specified (S16).

  The control unit 33 identifies an intersection line where the identified traveling surface and the spherical surface intersect (S17). The control unit 33 determines whether or not there are two or more intersection lines (S18), and if there are not two or more intersections (NO in S18), the intersection line is specified as the vehicle position (S19). When there are two or more intersection lines (YES in S18), the control unit 33 selects the intersection line using the previous positioning result and the subsequent travel history, the positioning result in the GPS receiver (S20), and the step The process of S19 is performed.

  The control unit 33 determines whether or not there is an instruction to end the process (S21). If there is no end instruction (NO in S21), the control unit 33 continues the process from step S11 and continues to specify the vehicle position. When there is an end instruction (YES in S21), the control unit 33 ends the process.

  In the above-described processing, when 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. You can also

Embodiment 2
In the first embodiment, the vehicle position is specified based on the arrival time of the signal from one transmitter 20, but the vehicle position may be specified based on the arrival time difference between the signals of the two transmitters. it can. Even in this case, the number of transmitters can be limited to two, and the vehicle position can be obtained with a small number of transmitters.

  FIG. 11 is an explanatory view showing another example of specifying the vehicle position. In this case, in addition to the transmitter 20, the transmitter 40 is installed at a predetermined position. The configuration of the transmitter 40 is the same as that of the transmitter 20. When a signal (positioning signal) is received from the transmitter 20 and the transmitter 40 at a certain point P1 on the road, the control unit 33 receives and transmits the signals of the transmitter 20 and the transmitter 40. And the arrival time until the signal reaches the in-vehicle device 30 from each of the transmitter 20 and the transmitter 40 is calculated. In this case, the signal transmission time can be obtained from the transmission time information included in the signal. The control unit 33 calculates an arrival time difference that is a difference between arrival times of the respective signals.

  The control unit 33 calculates the distance corresponding to the arrival time difference ΔT1 by integrating the speed of light with the arrival time difference ΔT1 of the signal, and focuses on the positions of the transmitter 20 and the transmitter 40 and makes the calculated distances equal. The curved surface W1 is specified. That is, it can be seen that the position of the own vehicle is on the rotating hyperboloid W1.

  On the other hand, when the control unit 33 receives signals from the transmitter 20 and the transmitter 40, the control unit 33 uses the road shape information of the road (link: the road between intersections) and the height information of the vehicle-mounted device 30 based on the road shape information. Identify the virtual driving surface of the car. When the road is a straight road, the traveling surface is a plane, and when the road is curved, the traveling surface is a curved surface.

  The control unit 33 specifies the own vehicle position as an intersection line intersecting the rotating hyperboloid W1 and the traveling surface. As a result, the vehicle position can be accurately identified only by receiving signals from the two transmitters 20 and 40.

  Assuming that the vehicle continues to travel and receives signals from the transmitter 20 and the transmitter 40 at the point P2 on the road, the control unit 33 adds the speed of light to the arrival time difference ΔT2 of the signal as in the case of the point P1. Thus, the distance corresponding to the arrival time difference ΔT2 is calculated, and the rotational hyperboloid W2 having the same calculated distance is identified with the positions of the transmitter 20 and the transmitter 40 as the focal points.

  On the other hand, when the control unit 33 receives signals from the transmitter 20 and the transmitter 40, the control unit 33 determines the virtual traveling surface of the host vehicle based on the road shape information of the road on which the host vehicle travels and the height information of the in-vehicle device 30. Identify.

  The control unit 33 specifies the own vehicle position as an intersection line intersecting the rotating hyperboloid W2 and the traveling surface. Thereafter, by repeating the same operation, the control unit 33 can continue to specify the vehicle position with high accuracy each time a signal is received from the transmitter 20 and the transmitter 40.

  FIG. 12 is an explanatory diagram showing the concept of the method for specifying the vehicle position when two transmitters are used. The example of FIG. 12 shows a specifying method when the arrival time difference between the signals from two transmitters is known. As shown in FIG. 12, first, the position of the vehicle is focused on the positions of the transmitter 20 and the transmitter 40, and the speed of light is integrated with the arrival time difference of each signal from the transmitter 20 and the transmitter 40 to the vehicle-mounted device 30. It exists on a rotating hyperboloid W having the same distance. Next, the vehicle position on the rotating hyperboloid W is determined.

  The control unit 33 specifies a virtual travel surface of the host vehicle based on the road shape information of the road on which the host vehicle travels and the height information of the vehicle-mounted device 30, and intersects the rotation hyperboloid W with the travel surface. Identified as an intersection line. As a result, the vehicle position can be accurately identified only by receiving signals from the two transmitters 20 and 40.

  Next, the operation of the in-vehicle device 30 will be described. FIG. 13 is a flowchart showing a processing procedure for specifying the position of the host vehicle according to the second embodiment. The control unit 33 acquires area information indicating a range in which it can be estimated that the vehicle is present from the GPS, the navigation system, or the like (S31). The control unit 33 determines whether or not a signal has been received from each of the transmitters 20 and 40 (S32). If no signal has been received (NO in S32), the processing after step S31 is continued. As a result, the vehicle continues to travel while estimating (measuring) the range in which the vehicle exists.

  When a signal is received from the transmitters 20 and 40 (YES in S32), the control unit 33 acquires road shape information and height information of the vehicle-mounted device 30 (S33), and specifies a virtual traveling surface of the own vehicle. (S34). Based on the received signals, the control unit 33 calculates the arrival time difference between the transmitters 20 and 40 of each signal from the vehicle-mounted device 30 (S35), and the distance obtained by adding the speed of light to the calculated arrival time difference. Based on the above, a rotation hyperboloid having the focal point at the position of the transmitters 20 and 40 is specified (S36).

  The control unit 33 identifies an intersection line where the identified traveling surface and the rotating hyperboloid intersect (S37), and identifies the intersection line as the vehicle position (S38). The control unit 33 determines whether or not there is an instruction to end the process (S39). If there is no end instruction (NO in S39), the control unit 33 continues the process after step S31 and continues to specify the vehicle position. If there is an end instruction (YES in S39), the control unit 33 ends the process.

  In the above example, each transmitter 20, 40 includes a crystal oscillator that generates a reference clock signal having the same period T, whereby each transmitter 20, 40 operates with a reference clock signal having the same period. The length of unit time can be made to coincide with each other in the transmitters 20 and 40. For example, the time length of 1 μs in each transmitter 20 and 40 can be matched.

  However, the oscillation frequency of the crystal oscillator that generates the reference clock signal may cause an error due to secular change or the like, and the period (frequency) of the reference clock signal of each transmitter 20 or 40 may shift. Hereinafter, a method for making the reference clock signals of the transmitters 20 and 40 have the same period will be described.

  Each transmitter 20, 40 is provided with a phase-locked loop (PLL). For example, the transmitter 20 transmits a signal to the transmitter 40 wirelessly or by wire. The transmitter 40 extracts the period (or frequency) of the reference clock signal from the received signal and adjusts the period (frequency) of the reference clock signal so as to be the same period as the extracted period. Thereby, even if the period of the reference clock signal changes from the initial value for some reason (for example, aging), the period of the reference clock signal of the transmitter 40 is set by the signal transmitted by the transmitter 20. Can be adjusted. Thereby, each transmitter 20 and 40 can operate | move with the reference clock signal of the mutually same period, The time length of unit time can be made to correspond in each transmitter 20 and 40. FIG.

  In addition, a signal transmitted by a GNSS satellite including GPS is received, a signal of a reference oscillation frequency (for example, about 10 MHz) is extracted from the received signal, and the reference clock signal is extracted based on the extracted signal of the reference oscillation frequency. The period (frequency) can also be adjusted.

  As described above, in the present invention, the position of the vehicle can be accurately identified by installing one transmitter without using a plurality of transmitters. 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 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.

  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.

  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 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 an example which pinpoints the own vehicle position. It is explanatory drawing which shows the concept of the identification method of the own vehicle position at the time of using one transmitter. It is explanatory drawing which shows the structure of road shape information. It is explanatory drawing which shows the other example which pinpoints the own vehicle position. It is explanatory drawing which shows an example of correction | amendment at the time of signal reception. It is a flowchart which shows the process sequence which pinpoints the position of the own vehicle. It is explanatory drawing which shows the other example which pinpoints the own vehicle position. It is explanatory drawing which shows the concept of the identification method of the own vehicle position at the time of using two transmitters. 10 is a flowchart showing a processing procedure for specifying the position of the host vehicle in the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical beacon 20, 40 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 Navigation part

Claims (6)

In a vehicle position specifying system including a transmitter installed at a predetermined point and transmitting a predetermined signal, and an in-vehicle device that receives a signal transmitted from the transmitter and specifies a position,
The in-vehicle device is
Storage means for storing transmission point information of the transmitter;
Arrival time acquisition means for acquiring the arrival time of the signal transmitted by the transmitter;
Road shape information acquisition means for acquiring road shape information related to the road shape;
Based on the transmission point information, arrival time and road shape information, a specifying means for specifying the vehicle position ;
Storage means for storing the height information of the mounting position ,
The specifying means is:
An intersection line between a virtual traveling surface of the vehicle determined by the road shape information and height information and a virtual spherical surface determined by the transmission point information and arrival time is specified as the vehicle position. vehicle location system according to claim Rukoto Oh. The in-vehicle device is
Comprising area information acquisition means for acquiring area information indicating an existing area in which the vehicle is present;
The specifying means includes
2. The system according to claim 1 , wherein an intersection line between the traveling surface and the phantom spherical surface in an existing area indicated by the area information acquired by the area information acquiring unit is specified as a vehicle position. The vehicle location system described. The area information is
The vehicle position specifying system according to claim 2 , wherein the vehicle position specifying system is information related to a vehicle position acquired by a car navigation system or a GPS receiver, or information related to a communication point with a roadside device. The in-vehicle device is
Comprising storage means for storing the traveling history information of the own vehicle;
The area information acquisition means includes
The vehicle position specifying system according to claim 2 , wherein the area information is acquired based on travel history information from the vehicle position specified most recently. The travel history information is
The vehicle position specifying system according to claim 4 , comprising at least one of information related to a travel distance, a travel speed, an acceleration / deceleration, or a travel direction. The transmitter is
Comprising transmission means for transmitting transmission time information for specifying a signal transmission time;
The arrival time acquisition means includes
Based on the transmission time of the reception time and the signal of the signal, the vehicle position according to any one of claims 1 to 5, characterized in that is arranged to acquire the arrival time of the signal Specific system.

Images