JP2008196906A - Vehicle position detection system, on-board equipment and vehicle position detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle position detection system, on-board equipment and vehicle position detection system capable of precisely detecting the position of the vehicle. <P>SOLUTION: An on-board equipment 30 receives every communicating position, its error range, and position of stop line of respective on-road equipments 21, 22 and 23 by communicating with a light beacon 10, stores the received information and at the same time starts to measure the travelling distance, and repeatedly estimates the vehicle position at each prescribed time elapsed. The on-board equipment 30 acquires the position of communication and the error range by communication with the on-road equipments 21, 22 and 23, the estimated value of the vehicle position estimated just before the communication time is updated so as to minimize the estimated error of the position of the vehicle based on the error range of the communication spot and error range of the travel distance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle position detection system that can accurately detect the position of a vehicle, an on-vehicle device that constitutes the vehicle position detection system, and a vehicle position detection method.

  Conventionally, in a factory or a monorail, an induction wireless device has been installed in parallel with the traveling track of the vehicle, and the vehicle's antenna has received radio waves from the induction wireless device so that the vehicle position can always be accurately and grasped. There is known a system capable of improving workability by notifying an operator of the position of the vehicle and stopping the vehicle at a predetermined position with high accuracy. In this system, the position of the vehicle can always be accurately obtained (for example, within an error range of about 10 cm). However, this system is based on the premise that the vehicle moves on a predetermined track, and ground equipment such as an induction radio device and the antenna of the vehicle need to be within a relatively short distance. For this reason, it is impossible to apply this system to a vehicle traveling on a road whose traveling direction is not always determined.

  On the other hand, there are self-contained navigation, satellite navigation, map matching, hybrid navigation, and the like as methods for detecting the position of a vehicle widely used in navigation. Self-contained navigation uses a distance sensor, an azimuth sensor, an angular velocity sensor, etc., for example, based on the azimuth angle of the vehicle traveling with respect to an orthogonal coordinate system based on the longitude-latitude coordinate system and the traveling distance per unit time. Although it is calculated, consistency with the road is not taken into consideration, and there is a problem that errors in the vehicle position accumulate as the travel distance increases.

  Satellite navigation uses GPS (Global Positioning System), and the detected position includes an error of about 10 to 20 m. Since GPS is used, an in-vehicle sensor such as a distance sensor, an azimuth sensor, or an angular velocity sensor is unnecessary. However, on roads under elevated roads, roads between buildings, mountain roads, roadside trees, etc., radio waves cannot be received from a predetermined number of GPS satellites, and the detection accuracy is greatly degraded. is there.

  In addition, the map matching method detects the position of the vehicle in consideration of the consistency (matching) between the travel locus by the self-contained navigation and the road map (see Patent Document 1). That is, the most probable road is selected from a plurality of road candidates considered to be traveling while comparing the trajectory obtained by the self-contained navigation with the road map data. Then, when the number of candidate roads is limited to one, the traveling locus of the vehicle obtained by the self-contained navigation is matched with the road. However, if the limited road is wrong, there is a problem that position detection after that becomes impossible.

  Hybrid navigation is a combination of satellite navigation and map matching, and it rationally estimates the position of the vehicle and identifies the road on which it is traveling, taking into account the errors between autonomous navigation and satellite navigation. (See Patent Document 2). In hybrid navigation, for example, the position of a vehicle is detected using a map matching method in normal times. When the vehicle position cannot be detected by the map matching method, the vehicle position and direction are detected by satellite navigation to estimate the vehicle position, and the vehicle position is detected in consideration of consistency with the road map data. To do. With hybrid navigation, except for special cases, there is almost no possibility of mistaken roads on which vehicles are traveling, and the positional accuracy in the direction of the road is within an error range of about 10 m on average. In the target navigation, the accuracy level is almost no problem in practical use.

As described above, the vehicle position in the road direction that can be detected by the method used in navigation has an error of about 10 m on average, and if the vehicle travels a long distance, the vehicle position error When the vehicle runs on a road under an overpass, a road in a tunnel, a road sandwiched between buildings, a mountain road, or a road covered with roadside trees, communication with a GPS satellite becomes impossible. There are times when the accuracy of the vehicle position temporarily deteriorates. Therefore, it communicates with on-road equipment such as an optical beacon, radio beacon or magnetic nail, or senses on-road equipment such as an ultrasonic detector, and temporarily corrects the position temporarily at that time (for example, the sensing range is If it is 4m, the position error at the time of communication will be about 2m with 2 sigma if there is no dead time), but in order to always keep the vehicle position highly accurate, It is necessary to install such equipment, which is not realistic. On the other hand, as a safe driving assistance that has become a hot topic in recent years, when it is dangerous for a vehicle to pass through an intersection, technical development has been performed to stop the vehicle before the intersection by performing deceleration control of the vehicle. Yes.
JP-A-63-148115 JP-A-2-275310

  However, in the conventional vehicle position detection method, since the detection accuracy has an error of about 10 m on average, the vehicle position is detected when a situation that prevents a traffic accident near an intersection occurs. Even when trying to stop the vehicle before the stop line, the vehicle may stop over the stop line and enter the pedestrian crossing, which may cause harm to pedestrians crossing. For the purpose of assisting safe driving of the vehicle, there is a problem that the conventional vehicle position detection method cannot cope with the detection accuracy of the vehicle position, although it is considered that the error needs to be at least about 1 m.

  The present invention has been made in view of such circumstances, and provides a vehicle position detection system that can accurately detect the position of a vehicle, an in-vehicle device that constitutes the vehicle position detection system, and a vehicle position detection method. For the purpose.

  A vehicle position detection system according to a first aspect of the present invention includes a plurality of transmission devices and in-vehicle devices installed along a road, and receives a signal transmitted from the transmission device by the in-vehicle device to detect the position of the vehicle. In the detection system, the transmission device includes a transmission unit that transmits a signal indicating that the vehicle has passed a predetermined point to the in-vehicle device, and the in-vehicle device includes a reception unit that receives the signal; When the signal is received by the receiving means, the first acquisition means for acquiring the position information of the point corresponding to the signal and the error information related to the position information, and the vehicle travel distance information and the error information related to the travel distance information are acquired. It is characterized by comprising a second acquisition means and a detection means for detecting the position of the vehicle based on the information acquired by the first acquisition means and the second acquisition means.

  The vehicle position detection system according to a second aspect of the present invention is the vehicle position detection system according to the first aspect, wherein the in-vehicle device is based on the travel distance information acquired by the second acquisition unit and the vehicle Estimating means for estimating the position; calculating means for calculating a positional deviation between the position of the point obtained from the position information acquired by the first acquiring means and the position estimated by the estimating means; and the position information and the travel distance Correction means for correcting the positional deviation calculated by the calculation means based on error information relating to each of the information, and each time the signal is received, the vehicle estimated by the estimation means based on the positional deviation corrected by the correction means Update means for updating the position, and the estimation means is further configured to perform predetermined processing based on the vehicle position updated by the update means and the travel distance information acquired by the second acquisition means. The position of the vehicle is estimated every time the vehicle passes or a predetermined distance travels, and the detection means detects the position of the vehicle estimated by the estimation means or the position of the vehicle updated by the update means. It is configured as described above.

  In the vehicle position detection system according to a third aspect of the present invention, in the second aspect, the in-vehicle device includes a third acquisition unit that acquires a travel direction of the vehicle, and the estimation unit acquires the travel direction acquired by the third acquisition unit. Based on the above, it is configured to estimate the position of the vehicle.

  The vehicle position detection system according to a fourth aspect of the present invention is the vehicle position detection system according to the second aspect or the third aspect, wherein the detection means detects the position of the vehicle estimated by the estimation means when no signal is received by the reception means. It is comprised by these.

  The vehicle position detection system according to a fifth aspect of the present invention is the vehicle position detection system according to the third aspect, wherein the in-vehicle device includes a fourth acquisition unit that acquires a direction of a road direction, a direction acquired by the fourth acquisition unit, and the third acquisition unit. An azimuth difference calculating means for calculating an azimuth difference from the acquired traveling azimuth, and the detecting means is acquired by the second acquiring means when the azimuth difference calculated by the azimuth difference calculating means is greater than a predetermined threshold value. The vehicle travel distance information and error information are removed to detect the position of the vehicle.

  The vehicle position detection system according to a sixth aspect of the present invention is the vehicle position detection system according to the fifth aspect, wherein the detection means includes a travel direction acquired by the third acquisition means and a direction acquired by the fourth acquisition means for a predetermined travel distance or more. Are different from each other, the vehicle travel distance information and error information acquired by the second acquisition means during the travel distance or more are removed to detect the position of the vehicle.

  In a fifth aspect of the vehicle position detection system according to the seventh aspect of the present invention, the detection means differs in the traveling direction acquired by the third acquisition means and the direction acquired by the fourth acquisition means for a predetermined time or more. In this case, the vehicle travel distance information and error information acquired by the second acquisition means are removed during the predetermined time or longer to detect the position of the vehicle.

  The vehicle position detection system according to an eighth aspect of the present invention is the vehicle position detection system according to the fifth aspect, wherein the detection means includes a traveling direction acquired by the third acquisition means and a direction acquired by the fourth acquisition means at two different points on the road. Is different, the vehicle travel distance information and error information acquired by the second acquisition means are removed between the two points to detect the position of the vehicle.

  An in-vehicle apparatus according to a ninth aspect of the present invention is an in-vehicle apparatus that receives a predetermined signal and detects the position of the vehicle, the receiving means receiving a signal indicating that the vehicle has passed a predetermined point, and the receiving means When receiving a signal, the first acquisition means for acquiring the position information of the point corresponding to the signal and the error information related to the position information, and the second acquiring the error information related to the travel distance information of the vehicle and the travel distance information It comprises an acquisition means and a detection means for detecting the position of the vehicle based on the information acquired by the first acquisition means and the second acquisition means.

  A vehicle position detection method according to a tenth aspect of the present invention is a vehicle position detection method for detecting a position of a vehicle by receiving signals transmitted by a plurality of transmission apparatuses installed along a road by an in-vehicle apparatus, wherein the transmission apparatus comprises: A signal indicating that the vehicle has passed a predetermined point is transmitted to the in-vehicle device, and when the in-vehicle device receives the signal, the vehicle-mounted device acquires position information corresponding to the signal and error information related to the position information. The vehicle travel distance information and error information related to the travel distance information are acquired, and the position of the vehicle is detected based on the acquired information.

  In the first invention, the ninth invention, and the tenth invention, each transmission device transmits a signal indicating that the vehicle has passed a predetermined point (for example, a communication point between the in-vehicle device and each transmission device). Send to. When the in-vehicle device receives the signal transmitted by the transmission device, the on-vehicle device acquires position information of a point corresponding to the received signal and error information related to the position information. The position information may be, for example, a distance from a preset reference point to the communication point, or may be an absolute position of the communication point. The error information can be an error range including a communication range between the in-vehicle device and the transmission device, and for example, a standard deviation of the position error can be used. The in-vehicle device receives and stores the position information of each transmitting device and error information related to the position information in advance from an external communication device (for example, an optical beacon, a radio wave beacon, a mid-range communication device, or a wide-area communication device) The stored position information and error information can be acquired when a signal from each transmission device is received. Alternatively, the position information and error information of each transmitter can be included in advance in the map database, and can be acquired from the map database when a signal from each transmitter is received.

  The in-vehicle device acquires travel distance information and error information related to the travel distance information according to the travel of the vehicle. The travel distance information is, for example, a travel distance from a preset reference point (for example, a point where measurement of the travel distance is started), and can be acquired from an in-vehicle distance measurement device. Further, the error information is an error range of the distance measuring device, and for example, a standard deviation of a travel distance error can be used. For example, the in-vehicle device starts measuring the travel distance from a predetermined reference point based on the acquired information, and estimates the position of the vehicle from time to time based on the travel distance and the travel distance error. Each time the in-vehicle device receives a signal from each transmission device, it acquires the position of the communication point, and updates the estimated vehicle position based on the travel distance error and the position error so that the estimation error of the vehicle position becomes small. . The in-vehicle device further measures the travel distance from the updated vehicle position, and repeats estimation of the position of the vehicle based on the travel distance and the travel distance error. Thereby, even if the mileage of the vehicle becomes long, the estimated position of the vehicle can be updated by acquiring the position of the predetermined communication point based on the signal received from each transmission device, The estimation error of the vehicle position can be reduced and the vehicle position can be detected with higher accuracy than in the past.

  In the second invention, the in-vehicle device determines in advance the time point or point at which the measurement of the travel distance is started. For example, the measurement of the travel distance can be started from a point of time passing through a predetermined reference point (for example, a point upstream of the stop line at the intersection). The in-vehicle device estimates the position of the vehicle every time a predetermined time elapses or a predetermined distance travels based on the travel distance information (travel distance) of the vehicle. Each time the in-vehicle device receives a signal from the transmission device, the in-vehicle device calculates a positional deviation between the position of the predetermined point (communication point) and the estimated position of the vehicle. The in-vehicle device corrects the positional deviation so that the estimation error of the estimated position of the vehicle is reduced based on error information relating to each of the position information and the travel distance information, for example, the standard deviation of the position error and the standard deviation of the travel distance error. Based on the corrected positional deviation, the estimated position of the vehicle is updated. The in-vehicle device updates the position of the vehicle every time it communicates with the transmission device. The in-vehicle device repeats estimation of the vehicle position every time a predetermined time elapses or a predetermined distance travels based on the updated vehicle position and the subsequent travel distance information. The in-vehicle device detects the position of the vehicle that is estimated every time a predetermined time elapses or the position of the vehicle that is updated at a communication point with the transmission device.

  The position information and error range of a predetermined point (communication point) are acquired by communication with a plurality of transmission devices installed on the road, and the estimated vehicle position is updated according to the traveling state (travel distance) of the vehicle. Therefore, the position of the vehicle traveling on the road can be detected with high accuracy. For example, by providing accurate position information just before the stop line, it is possible to reliably stop the vehicle at the intersection stop line for a vehicle that can be automatically controlled.

  In the third invention, the in-vehicle device acquires the traveling direction of the vehicle, and estimates the position of the vehicle based on the acquired traveling direction. For example, the position of the vehicle can be obtained based on the travel distance for a predetermined time and the travel direction relative to the orthogonal coordinate system in the orthogonal coordinate system based on the longitude and latitude coordinate system. Thereby, not only when traveling along the road but also when traveling in any direction within the road, the position of the vehicle can be detected with high accuracy.

  In the fourth invention, when the vehicle-mounted device has not received a signal from the transmitting device, the vehicle position is determined based on the vehicle position updated at the latest communication point, the travel distance from the point, and the travel direction. And the estimated position of the vehicle is detected. Thus, every time the position of the vehicle is estimated, it is not necessary to update the estimated position of the vehicle, and the transmission device can be installed at a required separation distance, and each time a signal is received at a communication point with the transmission device. The vehicle position estimation error can be reduced.

  In the fifth invention, for example, the in-vehicle device acquires the direction of the road direction from the map database, and calculates the direction difference between the acquired direction of the road and the traveling direction of the vehicle. If the calculated in-direction difference is greater than a predetermined threshold, the vehicle-mounted device may have stopped at the facility beside the road or frequently changed lanes. Remove (not use) to detect vehicle position. As a result, the position of the vehicle can be specified as one-dimensional coordinates along the road direction, and there is no need to represent the position of the vehicle in two-dimensional coordinates, and the estimation and update processing of the position of the vehicle can be simplified. At the same time, the processing effort can be reduced.

  In the sixth invention, the in-vehicle device removes the travel distance information and error information of the vehicle acquired during that time when the travel direction of the vehicle and the direction of the road are different for a predetermined travel distance or more ( Detect vehicle position (without using). As a result, the position of the vehicle can be specified as one-dimensional coordinates along the road direction, and there is no need to represent the position of the vehicle in two-dimensional coordinates, and the estimation and update processing of the position of the vehicle can be simplified. At the same time, the processing effort can be reduced.

  In the seventh invention, the in-vehicle device removes (uses) the travel distance information and error information of the vehicle acquired during the predetermined time or more when the travel direction of the vehicle and the direction of the road are different. Without) detecting the position of the vehicle. As a result, the position of the vehicle can be specified as one-dimensional coordinates along the road direction, and there is no need to represent the position of the vehicle in two-dimensional coordinates, and the estimation and update processing of the position of the vehicle can be simplified. At the same time, the processing effort can be reduced.

  In the eighth invention, the in-vehicle device removes the travel distance information and error information of the vehicle acquired between the points when the travel direction of the vehicle and the direction of the road are different at two different points on the road. To detect the position of the vehicle. As a result, the position of the vehicle can be specified as one-dimensional coordinates along the road direction, and there is no need to represent the position of the vehicle in two-dimensional coordinates, and the estimation and update processing of the position of the vehicle can be simplified. At the same time, the processing effort can be reduced.

  In the present invention, even when the travel distance of the vehicle becomes long, the position of the predetermined communication point is acquired and the estimated position of the vehicle is updated based on the signal received from each transmission device. Therefore, the estimation error of the vehicle position can be reduced and the vehicle position can be detected with higher accuracy than in the prior art.

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 detection system according to the present invention. The vehicle position detection system according to the present invention includes road devices 21, 22, and 23, an in-vehicle device 30, and the like that are installed with an appropriate separation distance along a road. The on-road devices 21, 22, and 23 are, for example, ultrasonic sensors, IC tags, magnetic nails, optical sensors, and the like, and can identify a communication point by sensing radio waves, sound waves, light, magnetism, and the like. It is. In the example of FIG. 1, the road devices 21, 22, and 23 are installed on the road upstream of the stop line near the intersection, but are not necessarily limited to the road upstream of the intersection, and join the main road. It may be a road.

  The road devices 21, 22, and 23 have communication areas A1, A2, and A3 with the in-vehicle device 30 on the road. When the vehicle passes through the areas A1, A2, and A3, the in-vehicle device 30 receives a signal indicating that the vehicle passes through the areas A1, A2, and A3 from the road devices 21, 22, and 23. The road devices 21, 22, and 23 may perform one-way communication with the in-vehicle device 30 or may perform two-way communication.

  An optical beacon 10 is installed on the upstream side of the road device 21 (for example, about 1 km upstream of the intersection). In place of the optical beacon 10, a radio wave beacon, DSRC (Dedicated Short Range Communication), or the like can be used. The optical beacon 10 has a communication area B with the in-vehicle device 30 on the road. When the vehicle passes through the region B, the in-vehicle device 30 receives predetermined information from the optical beacon 10. The predetermined information includes, for example, the signal reception position (communication point position) in the area B of the optical beacon 10 and its error range, and the signal reception positions in the areas A1, A2, and A3 of the road devices 21, 22, and 23 ( Communication point position) and its error range. The error range can be a standard deviation (or variance) of the position error.

  That is, when the vehicle travels on the road toward the intersection, the in-vehicle device 30 communicates with the optical beacon 10 when passing through the region B, and receives the signal reception position (communication point position) in the area B of the optical beacon 10. ) And its error range, the communication positions of the road devices 21, 22, and 23, its error range, the position of the stop line, etc., and the received information is stored. Further, when the vehicle travels and communicates with the roadside device 21 in the area A1, the position (the position of the communication point) and the error range thereof are acquired from the stored information. Further, when the vehicle travels and communicates with the road device 22 in the area A2, the position (the position of the communication point) and the error range thereof are acquired from the stored information. Further, when the vehicle travels and communicates with the road device 23 in the area A3, the position (the position of the communication point) and the error range are acquired from the stored information.

  When the in-vehicle device 30 communicates with the optical beacon 10 in the area B, the measured traveling distance is reset to “0” and initialized, and the measurement of the traveling distance is started from this reference point, for a predetermined time (for example, The position of the vehicle is repeatedly estimated every time 0.01 seconds or 0.05 seconds). The in-vehicle device 30 acquires the position of the communication point when communicating with the road device 21, and the estimation error of the vehicle position is minimized based on the error range of the position of the communication point and the error range of the travel distance ( The estimated vehicle position is updated so as to be smaller. The in-vehicle device 30 may accumulatively add the subsequent travel distance to the travel distance when communicating with the optical beacon 10 in the region B as a reference (initial value).

  The in-vehicle device 30 is similarly used every time a predetermined time (for example, 0.01 seconds, 0.05 seconds, etc.) elapses based on the vehicle position updated at the communication point with the road device 21 and the travel distance from the position. Alternatively, the vehicle position is repeatedly estimated every time a predetermined travel distance (for example, 0.1 m, 0.2 m, etc.) is traveled. The in-vehicle device 30 acquires the position of the communication point by communicating with the road device 22, and the estimation error of the vehicle position is minimized (smaller) based on the error range of the position of the communication point and the error range of the travel distance. ) To update the estimated vehicle position. Thereafter, by repeating the same processing, the position of the vehicle is detected with high accuracy.

FIG. 2 is a block diagram showing the configuration of the in-vehicle device 30. The in-vehicle device 30 includes a control unit 31 including a CPU that performs various arithmetic processes. Note that the control unit 31 may be configured with a dedicated hardware circuit, or may be configured to execute a computer program having a predetermined processing procedure. A communication unit 32, a positioning unit 33, a map database 34, a display unit 35, an operation unit 36, a notification unit 37, a storage unit 38, and the like are connected to the control unit 31 via an internal bus. Global Positioning System) 331, a gyro sensor 332, a distance meter 333 for measuring a travel distance, and the like.

  The communication unit 32 has a communication function for performing communication with the optical beacon 10. Note that the communication unit 32 is not limited to the narrow-area communication such as the optical beacon 10, the radio beacon, or the DSRC. For example, the communication unit 32 may include a wireless LAN function such as a UHF band or a VHF band as the mid-range communication. Alternatively, communication functions such as a mobile phone, PHS, multiple FM broadcasting, and Internet communication may be provided as wide area communication. The communication unit 32 has a reception function for receiving signals transmitted by the road devices 21, 22, and 23.

  The positioning unit 33 receives radio waves from a plurality of GPS satellites by the GPS 331, and measures the position of the own vehicle. In addition to GPS331, DGPS (differential GPS) can also be mounted. DGPS can receive FM broadcasts or medium waves transmitted from a reference station whose position is known in advance, can correct the positional deviation calculated by GPS 331, and can improve the accuracy of the position of the vehicle. The positioning unit 33 measures the travel distance of the vehicle based on signals output from the distance meter 333 and the gyro sensor 332 and outputs the measured distance to the control unit 31. In addition, the positioning unit 33 measures the traveling direction of the vehicle based on the signal output from the gyro sensor 332 and the data of the GPS 331 and the map database 34, and calculates the difference in direction from the direction of the road to calculate the control unit 31. Output to. The distance meter 333 may be composed of a tire or wheel rotational speed sensor or a vehicle speed pulse.

  The display unit 35 is a liquid crystal display panel such as a windshield display or a head-up display, or a car navigation system or a rear monitoring monitor, and displays necessary information to the driver.

  The operation unit 36 includes various operation panels and functions as a user interface between the driver and the in-vehicle 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 alerting | reporting part 37 is provided with a speaker, and when warning a driver | operator under control of the control part 31, it outputs the content of a warning with an audio | voice. For example, when automatic driving such as deceleration processing is performed to stop the vehicle at the stop line, a message to that effect is output.

  The storage unit 38 stores an error range of the travel distance when the travel distance is measured by the distance meter 333. As the error range of the travel distance, for example, the standard deviation (or variance) of the travel distance error in the unit distance travel can be used. Since the standard deviation of the mileage error depends on the distance meter 333 including the tire of the vehicle or the weather, the value of the standard deviation can be changed according to the type of tire, the air pressure, the type of the distance meter 333, and the weather. it can. Further, the storage unit 38 stores a threshold value for determining the magnitude of the azimuth difference between the traveling direction of the vehicle and the direction of the road direction.

  The storage unit 38 also stores the communication positions of the road devices 21, 22, and 23 received through the communication unit 32 and their error ranges.

FIG. 3 is an explanatory diagram showing an example of the error range of the communication positions of the road devices 21, 22, and 23. In a rectangular coordinate system (x direction and y direction), when a communication range on the road (corresponding to the area A1 in FIG. 1) with the road device 21 is assumed as in the example of FIG. 3, the communication range is surrounded. A rectangular area (the length in the x direction is 2a and the length in the y direction is 2b) is set as an error range of the communication position. That is, the position of the communication point with the roadside device 21 is the center position of the rectangular area, and the error range extends from the center position by ± a in the x direction and by ± b in the y direction. For example, if you set 2 sigma a, dispersion in the x direction a ^2/4, and the standard deviation can be set to a / 2. Also, if you set the b and 2 sigma, variance in the y direction is b ^2/4, and the standard deviation can be set to b / 2. Note that the error range of the communication position depends on the characteristics of the road device, and a different error range may be set for each road device, or the same error range may be set. In the following, it is assumed that the error ranges of the communication positions of the road devices 21, 22, and 23 are the same. Further, the error range can be determined by actually traveling on a road and measuring the result.

  The control unit 31 uses communication positions with a plurality of on-road devices 21, 22, and 23 in order to improve position detection accuracy on the target road upstream of the intersection. However, the control unit 31 does not correct the communication position to the position of the vehicle as it is, but considers a plurality of communication positions, their error ranges, and vehicle dynamic characteristics, so that the position of the vehicle from moment to moment is accurately determined (for example, (Error within 1 m) is detected. Hereinafter, a vehicle position detection method will be described. Note that the position of the vehicle is expressed by a two-dimensional vector in an orthogonal coordinate system. In the following, capital letters are assumed to be vectors or matrices.

  When the position P (t) of the vehicle at time t is expressed by equation (1), the time t + 1 (the interval between time t and t + 1 is a predetermined time, for example, 0.01 seconds, 0.05 seconds, etc.) The vehicle position P (t + 1) can be expressed by equation (2). Alternatively, the time at which the vehicle has traveled a predetermined travel distance (for example, 0.1 m, 0.2 m, etc.) from time t can be set as time t + 1. Note that “T” added to the vector means transposition. Equation (2) shows the dynamic characteristics of the vehicle. Note that the position P (t) of the vehicle at time t is the true position (actual position) of the vehicle and is a position that cannot be observed. That is, the vehicle position detection is to obtain an optimum estimated position with respect to the true position P (t).

  Here, D (t) is expressed by equation (3), d (t) is the distance traveled by the vehicle from time t to time t + 1, and θ (t) is the travel distance of the vehicle relative to the orthogonal coordinate system. Azimuth. E (t) is expressed by equation (4), and e (t) is an error in the travel distance d (t). Further, the variance Q (t) of the error E (t) is expressed by the equation (5), and q is an error variance in unit distance traveling and can be a constant value.

  Further, the communication position S (t) acquired by communication with the road device at time t can be expressed by Expression (6). Here, G (t) is an error of the communication position S (t), and a covariance matrix R (t) of the error G (t) can be expressed by Expression (7). In Expression (7), a and b are each half of the length in the x direction and the y direction of the rectangular area which is the error range shown in FIG. That is, the covariance matrix R (t) is composed of variances in the x direction and the y direction when a and b are 2 sigma. Even if the average value of E (t) and G (t) is 0, generality is not lost.

  The optimum estimated position H (t) of the vehicle position P (t) at time t is expressed by a recurrence formula as shown in Expression (8) by the Kalman filter.

Here, Γ (t) is a variance of the estimation error of the estimated position H (t), and can be expressed by a recurrence formula like Formula (9). Further, “−1” attached to a matrix means an inverse matrix of the matrix. Further, the estimated position H (0) at the initial time 0 and the variance Γ (0) of the estimation error can be expressed by Expression (10) and Expression (11), respectively. Here, M is a priori information on the position of the vehicle before communicating with the optical beacon 10, and Σ is its error variance. If there is no a priori information, M = 0 and Σ ⁻¹ = 0, and the estimated position H (0) at initial time 0 and the variance Γ (0) of the estimated error are respectively expressed by equations (12) and (13). ). In addition, what is necessary is just to use the value, when a priori information is acquired by navigation.

Since Equation (6) is obtained only at the time of communication with the road device, it is assumed that the errors a and b in Equation (7) are sufficiently large values while communication with the road device is not performed. In Expression (8), if R ⁻¹ (t) = 0, the estimated position can be calculated repeatedly using Expression (8) as it is.

  When it is determined that a vehicle traveling on the road is traveling without stopping at a facility on the road or without changing lanes, the vehicle position is set to a two-dimensional vector as described above. It is possible to formulate only by the position (distance) in the road direction without considering the position in the width direction of the road. The determination that the vehicle does not stop at the facility beside the road or the lane change is not repeated is based on the difference between the direction of the vehicle and the direction of the road. It can be determined whether or not there is a deviation. If the traveling direction of the vehicle is deviated, the data during that time may not be used for detection of the vehicle position.

As a method for determining whether or not there is a deviation in travel direction, for example, when the distance between the road direction and the vehicle travel direction is equal to or greater than a predetermined distance threshold, the road direction direction and the vehicle travel direction are different. Is greater than or equal to a predetermined time threshold, or it can be determined that there is a deviation in the vehicle's driving direction when the difference in the direction of the road direction and the difference in the driving direction of the vehicle are different at both ends of any road section. .

  Next, the case where the position of the vehicle is formulated only by the position (distance) in the road direction will be described. The position of the vehicle in the road direction at time t is x (t), the travel distance traveled by the vehicle from time t to time t + 1 is d (t), the error of travel distance d (t) is e (t), and time t If the communication position acquired by communication with the road device is s (t) and the error of the communication position s (t) is g (t), Expression (14) and Expression (15) are established.

  In this case, Expression (14) represents the dynamic characteristics of the vehicle, and Expression (15) represents an observation expression. Further, the vehicle position x (t) is a true position (actual position) of the vehicle and is a value that cannot be observed.

The optimal estimated value h (t) of the vehicle position x (t) at time t and the variance γ (t) of the estimation error are expressed by the equations (16) and (18) by the Kalman filter. Here, k (t) is a correction coefficient called Kalman gain, and is expressed by Expression (17). Further, q (t) is a variance of the error e (t) of the travel distance d (t), and r (t) is a variance of the error g (t) of the communication position s (t). When the error variance in unit distance traveling is q, it can be expressed as q (t) = d (t) · q. Also, as shown in FIG. 3, when the length in the road direction of the communication range with the roadside device is 2c and the error range is set to 2c, if c is 2 sigma, the variance r (t) is a c ^2/4. If there is no a priori information on the position of the vehicle before communication with the optical beacon 10, equations (19) and (20) are established.

  Further, since Equation (15) is obtained only at the time of communication with the road device, it is assumed that the error c is sufficiently large in Equation (16) while communication with the road device is not performed. If (t) = 0, the estimated position can be calculated repeatedly using equation (16) as it is.

  Based on the above-described equations (16), (17), and (18), vehicle position detection, that is, optimal estimation of the vehicle position is performed as follows. That is, at time t−1, an optimal estimated value h (t−1) of the vehicle is obtained, and the travel distance d (t−1) traveled by the vehicle from time t−1 to time t The estimated position of the vehicle at t is estimated as h (t−1) + d (t−1).

  At time t, when communicating with a road device, the communication position s (t) is acquired from the storage unit 38, and the acquired vehicle communication position s (t) and the immediately preceding estimated value h (t-1) + d (t- By updating the previous estimated value h (t−1) + d (t−1) with a value obtained by integrating the correction coefficient k (t) with the deviation from 1), the optimum estimated value h of the vehicle position at time t is updated. (T) is obtained. When communication with the road device is not performed, the correction coefficient k (t) is set to 0, and the immediately preceding estimated value h (t-1) + d (t-1) is set to the optimum vehicle position at time t. By using the estimated value h (t), processing can be performed using the same equation regardless of whether or not there is communication with a road device.

  The correction coefficient k (t) is an error e (t−1) of the travel distance d (t−1) so that the variance γ (t) of the estimation error of the estimated value h (t) of the vehicle position becomes small. Is calculated based on the variance q (t-1) of the error and the variance r (t-1) of the error g (t-1) of the communication position s (t-1).

  Next, an example of vehicle position detection by the vehicle position detection system according to the present invention will be described. FIG. 4 is an explanatory diagram showing an example of vehicle position detection by the vehicle position detection system according to the present invention. In FIG. 4, to simplify the description, it is assumed that the target road is a straight road on the upstream side of the intersection. As shown in FIG. 4, an optical beacon 10 is installed at a point (communication point) upstream 800 m from the stop line of the intersection, and on the road from the stop line to points (communication points) 500 m, 300 m, and 150 m upstream. Devices 21, 22, and 23 are installed. Further, it is assumed that the vehicle on which the in-vehicle device 30 is mounted travels in the direction of the arrow toward the intersection.

  The time when the in-vehicle device 30 communicates with the optical beacon 10 is set to 0, and the time when the in-vehicle device 30 communicates with the road devices 21, 22, and 23 is set to t1, t2, and t3. When the standard deviation (square root of variance) of the position error of the communication point with the optical beacon 10 is 1 m, r (0) = 1. Also, assuming that the standard deviation of the error at the communication point with the road devices 21, 22, 23 transmitted from the optical beacon 10 to the in-vehicle device 30 is 1 m, r (t1) = r (t2) = r (t3) = 1 It becomes. Further, when the standard deviation of the error of the distance meter 333 is 0.05 m per 1 m travel distance, q = 0.005.

  At time 0 when the vehicle travels on the road toward the intersection and the in-vehicle device 30 communicates with the optical beacon 10, the travel distance of the vehicle is initialized to 0, and measurement of the travel distance is started from this point. In this case, s (0) = 0, h (0) = 0, and γ (0) = r (0) = 1.

When the in-vehicle device 30 communicates with the road device 21 at time t1, the travel distance d (t1-1) up to time t1-1 obtained by the distance meter 333 is set to 299. q (t1-1) = d (t1-1) · q = 299 × 0.0025 = 0.7475. Since r (t1) = 1, γ (t1) = 0.636 and k (t1) = 0.636. s (t1) = 80
Since 0−500 = 300, the optimum estimated value h (t1) of the vehicle position at time t1 is h (t1) = 299.6.

  In addition, when the in-vehicle device 30 communicates with the road device 22 at time t2, the travel distance d (t2-1) from time t1 to time t2-1 is set to 199. q (t2-1) = d (t2-1) · q = 199 × 0.0025 = 0.4975. Since r (t2) = 1, γ (t2) = 0.531, and k (t2) = 0.531. Since s (t2) = 800−300 = 500, the optimal estimated value h (t2) of the vehicle position at time t2 is h (t2) = 499.3.

  When the in-vehicle device 30 communicates with the road device 23 at time t3, the travel distance d (t3-1) from time t2 to time t3-1 is set to 151. q (t3-1) = d (t3-1) · q = 151 × 0.0025 = 0.3775. Since r (t3) = 1, γ (t3) = 0.476 and k (t3) = 0.476. Since s (t3) = 800−150 = 650, the optimal estimated value h (t3) of the vehicle position at time t3 is h (t3) = 650.2.

  As described above, the variance γ (t3) of the estimation error of the vehicle position at time t3 when the in-vehicle device 30 communicates with the roadside device 23 is γ (t3) = 0.476, and the standard deviation thereof is 0.690 m. Since the distance from the road device 23 to the stop line is 150 m, the variance of the distance error while traveling the distance 150 m from the point of the road device 23 to the stop line is 150 × 0.0025 = 0.375, The sum of γ (t3), that is, 0.476 + 0.375 = 0.851, is the variance of the vehicle position error on the stop line. The standard deviation of this dispersion is 0.922 m and can be within 1 m.

  If the estimated value of the vehicle position is not updated by communication with the road devices 21, 22, and 23, that is, if the vehicle position is detected only by the travel distance obtained from the distance meter 333, an error in the travel distance on the stop line. Is 800 × 0.0025 = 2 and the error variance γ (0) at the communication point with the optical beacon 10 is 1. Therefore, the variance of the vehicle position error is 3, and the standard deviation is 1.73, and the error increases. On the other hand, in the vehicle position detection method according to the present invention, the vehicle position error (standard deviation) is 0.922, which is reduced to about half, so that the vehicle position detection accuracy to the extent that it contributes to safe driving support. Can be obtained.

  Note that the number of road devices to be installed and the separation distance can be appropriately set according to the situation of the target road, the required detection accuracy of the vehicle position, and the like. Generally, as the number of road devices increases, the detection accuracy of the vehicle position improves, but the improvement rate of the detection accuracy tends to saturate. Therefore, the installation cost of the road device and the required detection accuracy are reduced. What is necessary is just to determine by comparison.

  Next, the operation of the in-vehicle device 30 according to the present invention will be described. 5 and 6 are flowcharts showing a procedure for detecting the vehicle position of the in-vehicle device 30. The control unit 31 determines whether or not there is communication with the optical beacon 10 (S11). If there is no communication (NO in S11), the control unit 31 continues the process of step S11 and waits for communication with the optical beacon 10.

  When there is communication with the optical beacon 10 (YES in S11), the control unit 31 communicates with the road devices 21, 22, and 23 from the optical beacon 10 (communication point) and its error range (for example, error variance). ) Is received (S12), and the communication point with the optical beacon 10 is set as a reference point (for example, a point where the measured travel distance is set to 0) (S13).

The control unit 31 measures the travel distance (S14), and determines whether or not there is a deviation in the travel direction of the vehicle (the difference in orientation between the travel direction of the vehicle and the direction of the road) (S15). As a method for determining whether or not there is a deviation in travel direction, for example, when the distance between the road direction direction and the vehicle travel direction is equal to or greater than a predetermined distance threshold, the road direction direction and the vehicle travel direction are It is determined that there is a driving direction deviation of the vehicle when the different time is equal to or greater than a predetermined time threshold or when the difference in the direction of the road and the difference in the driving direction of the vehicle are different at both end points of any road section. Can do.

  If there is no deviation in the travel direction (NO in S15), the control unit 31 validates the travel distance measurement data to use the travel distance data for detecting the vehicle position (S16), and whether or not a predetermined time has elapsed. Is determined (S17). The determination of whether or not the predetermined time has elapsed may include determining whether or not the time required for the vehicle to travel a predetermined distance has elapsed. In this case, the predetermined distance It also includes determining the presence or absence of progress. If the predetermined time has not elapsed (NO in S17), the control unit 31 continues the process of step S17 and waits until the predetermined time elapses.

  When the predetermined time has elapsed (YES in S17), the control unit 31 estimates the vehicle position based on the acquired travel distance (S18). The control part 31 determines the presence or absence of communication with a road apparatus (S19), and when there is no communication (it is NO at S19), it continues the process after step S14 and repeats estimation of a vehicle position.

  On the other hand, when there is a deviation in the traveling direction (YES in S15), the control unit 31 invalidates the measured data of the traveling distance (S20), for example, assuming that the vehicle has stopped at the facility beside the road, and the processing after step S19 Continue.

  When there is communication with the road device (YES in S19), the control unit 31 acquires from the storage unit 38 the position of the road device with the communication (position of the communication point) and the error range (for example, variance) of the position. (S21) Based on the acquired position of the communication point, the error range of the position, the error range of the travel distance acquired from the storage unit 38, etc., the variance of the estimation error of the vehicle position is obtained and the correction coefficient is calculated. (S22). Based on the calculated correction coefficient, the control unit 31 updates the estimated position of the vehicle estimated immediately before the time of communication with the road device (S23).

  The control unit 31 determines whether or not the communicated road device is the last road device on the target road (S24). If the road device is not the last road device (NO in S24), the processing from step S14 is continued. When it is the last road device (YES in S24), the control unit 31 determines whether the distance to the stop line is shorter than a predetermined threshold while measuring the travel distance (S25), and the distance to the stop line. Is not shorter than the threshold (NO in S25), the process of step S25 is continued.

  When the distance to the stop line is shorter than the threshold (YES in S25), the control unit 31 issues a warning of deceleration (S26), performs vehicle deceleration processing (S27), stops the vehicle at the stop line, and performs processing. finish. The vehicle deceleration process can be determined based on the color of the traffic light and its display time if a traffic light is installed at the intersection, or if there is no traffic light at the intersection, or When joining a road, deceleration processing can be performed according to the distance to the stop line.

The method by which the in-vehicle device 30 transmits a signal for acquiring the position of the predetermined communication point to the in-vehicle device 30 is not limited to the above example, and other configurations can be used. FIG. 7 is a schematic diagram showing another example of the outline of the vehicle position detection system according to the present invention. As shown in FIG. 7, optical beacons 10, 10, and 10 can be installed instead of the road devices 21, 22, and 23. In this case, each optical beacon 10 can transmit the position of its own communication point and its error range to the in-vehicle device 30. Alternatively, the most upstream optical beacon 10 can transmit the position of the communication point of another optical beacon 10 and its error range to the in-vehicle device 30. Instead of the optical beacon 10, a radio wave beacon, DSRC, or the like can be used.

  FIG. 8 is a schematic diagram showing another example of the outline of the vehicle position detection system according to the present invention. As shown in FIG. 8, instead of the optical beacon 10 of FIG. 1, a communication device 40 having a mid-range communication function such as a wireless LAN may be installed. In this case, the communication device 40 transmits the position of the communication point of the road devices 21, 22, and 23 and the error range of the position to the in-vehicle device 30. Note that the communication device 40 may use a device that performs processing such as signal control, traffic information collection, and traffic information provision. The communication device 40 is not limited to mid-range communication, and may be a device having a wide-area communication function such as FM broadcasting, a mobile phone, and Internet communication.

  FIG. 9 is a schematic view showing another example of the outline of the vehicle position detection system according to the present invention. As shown in FIG. 9, instead of the road devices 21, 22, and 23, transmission devices 50 and 50 that transmit radio waves of a predetermined frequency are installed, and radio waves from the two transmission devices 50 and 50 are transmitted by the in-vehicle device 30. The position of a predetermined communication point and its error range can also be obtained using a method such as hyperbolic navigation according to the magnitude of the phase difference of the received radio wave. Note that the configurations of FIGS. 1 and 7 to 9 described above may be combined.

  As described above, in the present invention, the position of the vehicle can be detected with higher accuracy than in the prior art. In addition, the vehicle can be reliably stopped at the stop line to contribute to safe driving support. Further, not only when the vehicle travels on a straight road but also when traveling on a road in an arbitrary direction, the position of the vehicle can be detected with high accuracy. Further, it is possible to simplify the estimation and update processing of the position of the vehicle, and to reduce the processing effort.

  In the present invention, the GPS is not used after communication with the road device. However, if the accuracy of the GPS is improved in the future (for example, an error of about 1 to 2 m on average), the GPS can be combined with the autonomous navigation. Self-contained navigation can be supplemented. This not only improves the accuracy slightly as a whole, but also makes it possible to detect the position within the GPS error range by using the GPS even when the autonomous navigation cannot be used due to the above abnormalities. . Of course, the improvement in accuracy is not realized until the subsequent communication with the road device. When formulating a concept using GPS, a term related to GPS is added to the observation formula represented by formula (6). That is, the GPS term is expressed by equation (21).

  Here, S2 (t) is positioning data obtained by GPS, and U (t) is the error. Therefore, the observation equation corresponding to Equation (6) can be expressed by Equation (22) by combining Equation (6) and Equation (21). Here, SS (t) is a four-dimensional vector.

In the above-described embodiment, the position of the communication point with the road devices 21, 22, 23 may be the position (distance) from the position of the communication point (reference point) with the optical beacon 10, or the road device 22 The communication point may be a position (distance) from the communication point of the road device 21, and the position of the communication point of the road device 23 may be a position (distance) from the communication point of the road device 22.

  The mathematical formulas for estimating the position of the vehicle shown in the above-described embodiment are merely examples, and the mathematical formulas are not limited to these, and mathematical formulas appropriately modified can be used.

  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 mimetic diagram showing the outline of the vehicle position detection system concerning the present invention. It is a block diagram which shows the structure of a vehicle-mounted apparatus. It is explanatory drawing which shows the example of the error range of the communication position of a road apparatus. It is explanatory drawing which shows the example of detection of the vehicle position by the vehicle position detection system which concerns on this invention. It is a flowchart which shows the detection procedure of the vehicle position of a vehicle-mounted apparatus. It is a flowchart which shows the detection procedure of the vehicle position of a vehicle-mounted apparatus. It is a schematic diagram which shows the other example of the outline | summary of the vehicle position detection system which concerns on this invention. It is a schematic diagram which shows the other example of the outline | summary of the vehicle position detection system which concerns on this invention. It is a schematic diagram which shows the other example of the outline | summary of the vehicle position detection system which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical beacon 21, 22, 23 On-road device 30 Car-mounted apparatus 31 Control part 32 Communication part 33 Positioning part 34 Map database 35 Display part 36 Operation part 37 Notification part 38 Storage part 40 Communication apparatus 50 Transmission apparatus

Claims (10)

A vehicle position detection system comprising a plurality of transmission devices and in-vehicle devices installed along a road, wherein a signal transmitted from the transmission device is received by the in-vehicle device to detect the position of the vehicle,
The transmitter is
A transmission means for transmitting a signal indicating that the vehicle has passed a predetermined point to the in-vehicle device;
The in-vehicle device is
Receiving means for receiving the signal;
A first acquisition unit that acquires position information of a point corresponding to the signal and error information related to the position information when the reception unit receives the signal;
Second acquisition means for acquiring vehicle travel distance information and error information relating to the travel distance information;
A vehicle position detection system comprising: detection means for detecting a position of the vehicle based on information acquired by the first acquisition means and the second acquisition means. The in-vehicle device is
Based on the travel distance information acquired by the second acquisition means, estimation means for estimating the position of the vehicle every time a predetermined time passes or travels for a predetermined distance;
Calculation means for calculating a positional deviation between the position of the point obtained by the position information acquired by the first acquisition means and the position estimated by the estimation means;
Correction means for correcting the positional deviation calculated by the calculation means based on error information relating to each of the position information and travel distance information;
Updating means for updating the position of the vehicle estimated by the estimation means based on the positional deviation corrected by the correction means each time the signal is received;
The estimation means further estimates the position of the vehicle every time a predetermined time elapses or a predetermined distance travels based on the vehicle position updated by the update means and the travel distance information acquired by the second acquisition means. It is configured as
The detection means includes
2. The vehicle position detection system according to claim 1, wherein the position of the vehicle estimated by the estimation means or the position of the vehicle updated by the update means is detected. The in-vehicle device is
Comprising a third acquisition means for acquiring the traveling direction of the vehicle;
The estimation means includes
The vehicle position detection system according to claim 2, wherein the position of the vehicle is estimated based on the travel direction acquired by the third acquisition means. The detection means includes
The vehicle position detection system according to claim 2 or 3, wherein when the signal is not received by the receiving means, the position of the vehicle estimated by the estimating means is detected. The in-vehicle device is
Fourth acquisition means for acquiring the direction of the road direction;
An azimuth difference calculating means for calculating a azimuth difference between the azimuth acquired by the fourth acquiring means and the traveling azimuth acquired by the third acquiring means;
The detection means includes
When the azimuth difference calculated by the azimuth difference calculation means is larger than a predetermined threshold, the vehicle travel distance information and error information acquired by the second acquisition means are removed to detect the position of the vehicle. The vehicle position detection system according to claim 3, wherein the vehicle position detection system is provided. The detection means includes
When the travel direction acquired by the third acquisition unit is different from the direction acquired by the fourth acquisition unit for a predetermined travel distance or more, the vehicle acquired by the second acquisition unit during the travel distance or more 6. The vehicle position detection system according to claim 5, wherein the vehicle position is detected by removing travel distance information and error information. The detection means includes
When the travel direction acquired by the third acquisition unit differs from the direction acquired by the fourth acquisition unit for a predetermined time or more, the travel distance of the vehicle acquired by the second acquisition unit for the predetermined time or longer 6. The vehicle position detection system according to claim 5, wherein the vehicle position is detected by removing information and error information. The detection means includes
If the travel direction acquired by the third acquisition unit and the direction acquired by the fourth acquisition unit are different at two different points on the road, the travel distance of the vehicle acquired by the second acquisition unit between the two points 6. The vehicle position detection system according to claim 5, wherein the vehicle position is detected by removing information and error information. An in-vehicle device that receives a predetermined signal and detects the position of the vehicle,
Receiving means for receiving a signal indicating that the vehicle has passed a predetermined point;
A first acquisition unit that acquires position information of a point corresponding to the signal and error information related to the position information when the reception unit receives the signal;
Second acquisition means for acquiring vehicle travel distance information and error information relating to the travel distance information;
An in-vehicle device comprising: a detecting unit that detects a position of the vehicle based on information acquired by the first acquiring unit and the second acquiring unit. A vehicle position detection method for detecting a position of a vehicle by receiving a signal transmitted by a plurality of transmission devices installed along a road with an in-vehicle device,
The transmitter is
A signal indicating that the vehicle has passed a predetermined point is transmitted to the in-vehicle device;
The in-vehicle device is
When receiving the signal, obtain position information of the point corresponding to the signal and error information related to the position information,
Acquire vehicle travel distance information and error information related to the travel distance information,
A vehicle position detection method that detects the position of a vehicle based on the acquired information.

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