JP2007078519A - Vehicle-mounted navigation system and map-matching method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform map matching with high map-matching accuracy. <P>SOLUTION: Information on roads through which own vehicle has passed in the past is stored in a road passage history storaging apparatus 7 as a road passage history. When a navigation controller 1 performs map-matching processing, to correct the display position of a position mark of own vehicle to a road position on a map, the display position of the position mark of own vehicle is determined, taking into consideration the road passage history stored in the road passage history storage apparatus 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an in-vehicle navigation device having a map matching function for correcting a vehicle position mark on a map to a road position, and a map matching method in the in-vehicle navigation device.

  2. Description of the Related Art Conventionally, an in-vehicle navigation device that detects a current position of a vehicle and displays an image in which a vehicle position mark indicating the current position of the vehicle is superimposed on a map is widely used. In this type of in-vehicle navigation device, in general, the absolute position of the vehicle is obtained based on a GPS signal transmitted from a GPS (Global Positioning System) satellite, and the vehicle is operated by self-contained navigation using an in-vehicle sensor such as a gyro sensor or a vehicle speed sensor The relative movement position is obtained, and the current position of the vehicle is specified from the absolute position and the relative movement position. At this time, the current position of the vehicle may not be detected correctly due to an error in the GPS signal or a detection error of the in-vehicle sensor. As a result, the vehicle position mark is displayed superimposed on the position off the road on the map. May be. In order to correct such a shift of the vehicle position mark on the map, the in-vehicle navigation device usually performs a process called map matching to correct the display position of the vehicle position mark on the road position of the map. I am doing so.

As a typical method of this map matching, the road closest to the current position of the detected vehicle is estimated to be the road where the vehicle is actually traveling, and the vehicle position mark is displayed on the road. Whenever the vehicle travels a predetermined distance, the vehicle's travel locus at the predetermined distance is obtained, and a road having a shape closest to the vehicle's travel locus is selected from roads existing near the current position of the vehicle. It is known that there is a pattern method that estimates that the vehicle is actually traveling and displays the vehicle position mark on the road, and a method that combines the projection method and the pattern method. (For example, refer to Patent Document 1).
JP-A-8-159788

  By the way, when the driver of the vehicle selects a road to travel from among a plurality of roads, if there is a road familiar to the driver, the driver selects the familiar road as the traveling path of the vehicle. The tendency is strong. Therefore, when performing the map matching as described above, if a road familiar to the driver is listed as a candidate for matching, it is highly likely that the road is actually a road on which the vehicle is traveling. .

  However, in the conventional map matching method as described in Patent Document 1 described above, roads familiar to the driver and other roads are treated equally without being particularly distinguished, so the vehicle actually In many cases, the vehicle position mark is mismatched on a road other than the road on which the vehicle is traveling, and there is a problem that sufficient matching accuracy cannot be obtained.

  The present invention has been developed in view of the above-described conventional situation, and an object thereof is to provide an in-vehicle navigation device and a map matching method capable of performing map matching with high matching accuracy.

  In order to achieve the above object, the present invention stores information on roads on which vehicles have passed in the past as road passing history, and when the current position of the vehicle does not match the road position on the map to be displayed, In correcting the display position of the vehicle position mark indicating the current position on the road position of the map, the display position of the vehicle position mark is determined in consideration of the road passage history.

  According to the present invention, when correcting the display position of the own vehicle position mark on the road position of the map, the display position of the own vehicle position mark is considered in consideration of the road passage history that is information on the road on which the vehicle has passed in the past. Therefore, map matching can be performed with high matching accuracy.

  Hereinafter, a specific embodiment of an in-vehicle navigation device to which the present invention is applied will be described in detail with reference to the drawings.

  The vehicle-mounted navigation device to which the present invention is applied detects the current position (vehicle position) of a vehicle (hereinafter referred to as the host vehicle) on which the vehicle-mounted navigation device is mounted, and indicates the host vehicle position. A map matching function that displays an image with the mark superimposed on the map and corrects the display position of the vehicle position mark on the road position of the map when the vehicle position does not match the road position of the map to be displayed It is what you have. In particular, the in-vehicle navigation device to which the present invention is applied stores information on the road on which the vehicle has passed in the past as a road passage history, and takes into consideration the road passage history at the time of map matching. It is characterized in that map matching can be performed with high matching accuracy by determining the display position of the position mark. Hereinafter, an in-vehicle navigation device as an embodiment of the present invention will be specifically described with a focus on the characteristic features of the present invention.

  A schematic configuration of the in-vehicle navigation device of the present embodiment is shown in FIG. As shown in FIG. 1, the in-vehicle navigation device of this embodiment includes a navigation controller 1 that controls the overall operation of the in-vehicle navigation device as a main component, and a GPS is provided on the input side of the navigation controller 1. The receiver 2, the in-vehicle sensor 3, the operation device 4, and the map data storage device 5 are connected to each other, and the display device 6 is connected to the output side of the navigation controller 1. Further, the in-vehicle navigation device of the present embodiment includes a road passage history storage device 7 for storing a road passage history as a configuration unique to the in-vehicle navigation device, and this road passage history storage device 7 is included in the navigation controller 1. It is connected. The road passing history storage device 7 may be realized using a predetermined memory area inside the navigation controller 1.

  The GPS receiver 2 receives a signal transmitted from a satellite of the global positioning system (GPS). The in-vehicle sensor 3 is a vehicle speed sensor or a gyro sensor mounted on the own vehicle. The GPS signal received by the GPS receiver 2 and the sensor detection value of the in-vehicle sensor 3 are sent to the navigation controller 1 as needed, and are used to specify the vehicle position.

  The operation device 4 is a user interface used for a passenger of the vehicle to input various instructions, and includes, for example, various operation buttons, a joystick, a touch panel type switch, and the like. An instruction from the vehicle occupant input using the operation device 4 is sent to the navigation controller 1 as needed.

  The map data storage device 5 stores map data handled by the navigation device of the present embodiment, and has a recording medium such as a DVD (Digital Versatile Disc). Here, the map data is composed of node data indicating points on the map and link data indicating roads connecting the nodes, and each node data includes the position coordinates, point attributes, point names, etc. of the points. Each link data includes data such as position coordinates of the start point and end point of the link, link length, road width, road attribute, road name, and the like. The map data is divided into data units (areas) that can be processed at a time by the navigation controller 1, and each section is uniquely identified by being given a section number, latitude and longitude data. It has a data structure that can be used.

  The map data stored in the map data storage device 5 is appropriately read based on a command from the navigation controller 1 and sent to the navigation controller 1. As the recording medium of the map data storage device 5, in addition to the above-described DVD, recording media having various specifications such as a CD (Compact Disc), a memory card, and a hard disk can be used. In addition, when the in-vehicle navigation device has a data communication function by wireless communication or the like, a configuration is adopted in which map data from a service center or the like that provides a map data distribution service is acquired and sent to the navigation controller 1 May be.

  The display device 6 displays an image in which a vehicle position mark indicating the vehicle position is superimposed on a map under the control of the navigation controller 1, for example, a liquid crystal installed on the center console of the vehicle. A display or a projector that projects and displays an image on the windshield of the vehicle is used.

  Under the control of the navigation controller 1, the road passage history storage device 7 stores information on the road on which the vehicle has passed in the past as a road passage history. Specifically, in this road passage history storage device 7, information such as the number of times the vehicle has passed with respect to the road and the last passage date are stored as a road passage history for each road on which the vehicle has passed in the past. This road passage history information is written and updated in the road passage history storage device 7 every time it is determined that the vehicle is passing a certain road.

  The navigation controller 1 is configured as a control unit having an input / output buffer circuit, a memory circuit, and the like with a microcomputer having a CPU, a ROM, and a RAM as a center. The navigation controller 1 executes a navigation program stored in advance in a ROM of a microcomputer and performs various arithmetic processes with the CPU, thereby controlling various operations in the in-vehicle navigation device of the present embodiment. In particular, the functions of the vehicle position specifying unit 11, the display control unit 12, the map matching processing unit 13, and the passing road history writing unit 14 are realized as parts related to the present invention. In these control function units in the navigation controller 1, the following processing is performed.

  The own vehicle position specifying unit 11 takes in the GPS signal from the GPS receiver 2 and the sensor detection value from the in-vehicle sensor 3 and uses the absolute position of the own vehicle based on the GPS signal as the sensor detection value from the in-vehicle sensor 3. The position of the vehicle is specified by correcting by the self-contained navigation.

  The display control unit 12 controls the display operation of the display device 6 by creating an image to be displayed on the display device 6 and supplying the image data of the image to the display device 6. Specifically, the display control unit 12 reads out the map data stored in the map data storage device 5, draws a map around the vehicle position based on the map data, and the vehicle position specifying unit. The vehicle position specified in 11 is specified on this map, and an image in which the vehicle position mark is superimposed on the vehicle position on the map is created. At this time, when the map matching processing for correcting the display position of the vehicle position mark is performed in the map matching processing unit 13, the display control unit 12 is an image in which the vehicle position mark is superimposed on the corrected display position. Create The image data of the image created by the display control unit 12 is sent to the display device 6. Then, when the display device 6 performs display processing based on the image data, an image in which the vehicle position mark is superimposed on the map is displayed on the display device 6.

  The map matching processing unit 13 displays the display position of the vehicle position mark when the vehicle position specified by the vehicle position specifying unit 11 does not match the road position of the display target map drawn by the display control unit 12. Is corrected on the road position of the map to be displayed. Specifically, the map matching processing unit 13 determines whether or not the vehicle position specified by the vehicle position specifying unit 11 is on the road position of the map to be displayed, and the vehicle position specifying unit 11. If it is determined that the vehicle position specified in step S1 is not on the road position of the map to be displayed, a plurality of roads existing around the vehicle position are extracted as matching candidates. Then, for example, the map matching processing unit 13 obtains a correlation between the movement of the vehicle at a predetermined time and the shape of the road extracted as a matching candidate, and matches the most probable road as the road on which the vehicle is traveling. The road is selected as a target road, and a predetermined position on the road is determined as the display position of the vehicle position mark.

  At this time, particularly in the in-vehicle navigation device of the present embodiment, when the map matching processing unit 13 selects a matching target road from a plurality of roads extracted as matching candidates, the map is stored in the road passage history storage device 7. The road passing history information is read out, and the matching target road is selected in consideration of the road passing history. That is, the map matching processing unit 13 checks whether or not a road passing history is stored for each of the plurality of roads extracted as matching candidates, and for a road in which the road passing history is stored, A learning value representing the degree of familiarity of the driver of the vehicle with respect to the road is calculated using the information on the road passage history. Then, the map matching processing unit 13 adds the learning value calculated based on the road passage history information to the above-described matching score that represents the degree of correlation between the movement of the vehicle and the road shape, and obtains a final score. The road with the highest score is selected as a matching target road, and a predetermined position on this road is determined as the display position of the vehicle position mark.

  The learning value is calculated by the map matching processing unit 13 as follows, for example. That is, as described above, the road passage history storage device 7 stores, for each road on which the vehicle has passed in the past, information such as the number of times the vehicle has passed with respect to the road and the date of the last passage as the road passage history. Yes. The map matching processing unit 13 reads the information on the number of times the vehicle has passed and the date of the last passage from the road passage history storage device 7, and based on the information on the number of times the vehicle has passed and the date of the last passage, According to 1), a learning value X is calculated. In the following calculation formula (1), Y is the number of times the vehicle has passed on the road, Z is the number of days elapsed from the last passage date of the vehicle on the road to the present, A is the first coefficient, and B is This is a second coefficient that is sufficiently smaller than the first coefficient. The first coefficient A and the second coefficient B may be set to optimum values obtained in advance by repeatedly performing a simulation using a computer.

X = A · Σ (1 / Y) −B · Z (1)
The learning value X calculated by using this formula (1) represents the degree of familiarity of the driver of the own vehicle that changes from day to day, and the value decreases as the frequency of use for the road decreases. ing. Further, the learning value X increases as the number of passes increases, but the increase amount decreases as the number of passes increases.

  In the calculation formula (1) as described above, there may be a case where the calculated learning value X is excessively large or a negative value is calculated. If the calculated learning value X is extremely large, only roads that are frequently used are selected as matching targets even if other roads that have a high degree of correlation with the movement of the vehicle are listed as matching candidates. In addition, when the calculated learning value X is a negative value, there is an inconvenience that it is difficult to select a road that has passed in the past as a matching target.

  Therefore, the map matching processing unit 13 provides an upper limit value and a lower limit value for the learning value calculated using the road passage history information. That is, when the value of X calculated by the calculation formula (1) exceeds the predetermined threshold C, the map matching processing unit 13 uses the threshold C as a learning value and is calculated by the calculation formula (1). When the value of X is less than 0, 0 is set as the learning value. Thereby, the above-described inconvenience when the learning value X calculated by the calculation formula (1) becomes extremely large or a negative value is calculated is effectively suppressed, and the optimum learning value is obtained. Can do. The threshold value C may be set to an optimum value obtained by a simulation using a computer together with the first coefficient A and the second coefficient B in the calculation formula (1).

  The road passage history writing unit 14 performs a process of identifying the road on which the vehicle is currently passing and writing the information in the road passage history storage device 7 as a road passage history. Specifically, the road passing history writing unit 14 specifies a road that matches the vehicle position specified by the vehicle position specifying unit 11 or the vehicle position corrected by the map matching processing unit 13, and the road It is confirmed whether or not the road passage history for is already stored in the road passage history storage device 7. Then, if the road passage history for the road is not stored in the road passage history storage device 7, the road passage history writing unit 14 includes, as the road passage history of the road, information indicating that the number of passes is one time. Information indicating the current date is written in the road passage history storage device 7 in association with the identification number of the link representing the road. Further, if the road passage history for the road is already stored in the road passage history storage device 7, the road passage history writing unit 14 increments the value of the number of passes stored as the road passage history of the road. At the same time, the information on the last passage date is overwritten with the information indicating the current date, and the road passage history for the road is updated.

  FIG. 2 shows a flow of a series of processing by the navigation controller 1 when displaying an image in which the vehicle position mark is superimposed on a map on the display device 6 in the in-vehicle navigation device of the present embodiment configured as described above. It is a flowchart to show. The processing flow of FIG. 2 is repeatedly executed at a predetermined processing cycle. Here, a predetermined range of map data necessary for drawing a map to be displayed by the navigation controller 1 has already been read from the map data storage device 5 and stored in the memory inside the navigation controller 1. It will be explained as a thing.

  When the processing flow of FIG. 2 starts, the navigation controller 1 first captures the GPS signal from the GPS receiver 2 and the sensor detection value from the in-vehicle sensor 3 in step S1 to identify the vehicle position. In step S2, the navigation controller 1 determines whether map matching processing is necessary based on whether or not the vehicle position specified in step S1 is on the road position of the map to be displayed. If it is determined that the map matching process is necessary, the process proceeds to the next step S3. If it is determined that the map matching process is not necessary, the process proceeds to step S8.

  In step S3, the navigation controller 1 extracts a plurality of roads existing within a predetermined distance from the vehicle position specified in step S1 among roads included in the display target map as matching candidate roads. In step S4, the navigation controller 1 determines whether or not there is a road that has passed in the past among the plurality of matching candidate roads extracted in step S3, that is, the road passage history storage device 7 stores the road passage history. It is confirmed whether there is a road in which information is stored, and if there is a road that has passed in the past in the matching candidate roads, in the next step S5, information on the road passing history for the road is read out. Then, a learning value representing the degree of familiarity of the driver of the vehicle with respect to the road is calculated using the information on the road passage history.

  In step S6, the navigation controller 1 calculates a matching score based on the road shape and the like for each road extracted as a matching candidate in step S3. For the road whose learning value is calculated in step S5, the calculated matching score is calculated. A learning score is added to obtain a final score, and a road with the highest score is selected as a matching target road. In step S7, the navigation controller 1 determines a predetermined position on the matching target road selected in step S6 as the display position of the vehicle position mark.

  Next, in Step S8, the navigation controller 1 draws a map around the vehicle position, and superimposes the vehicle position mark on the vehicle position specified in Step S1 or the display position on the map determined in Step S8. The created image is created and the image data is sent to the display device 6. Thereby, the display device 6 displays an image in which the vehicle position mark is superimposed on the map.

  Thereafter, in step S9, the navigation controller 1 uses the road passing history information for the road determined as the display position of the own vehicle position mark, that is, the road on which the own vehicle is currently traveling. A process of writing in the history storage device 7 is performed, and the process returns to the process in step S1. If the road (link) determined to be the road on which the vehicle is currently traveling in step S9 is the same as the road (link) determined in the previous processing cycle, the duplicate road passing history is written. Instead, the process returns to step S1.

  As described above, in the in-vehicle navigation device of the present embodiment, when the navigation controller 1 performs the map matching process to correct the display position of the vehicle position mark on the road position of the map, the vehicle has passed in the past. Since the display position of the own vehicle position mark is determined in consideration of the road passage history that is the information of the road, the map matching can be performed with high matching accuracy. For example, as shown in FIG. 3, when the own vehicle enters either the road L2 or the road L3 parallel to each other from the road L1, for example, as shown in FIG. If the road is more familiar than the road L3, the driver of the own vehicle is more likely to select the road L2 as the road to be traveled, and the own vehicle is likely to be traveling on the road L2. However, in the conventional map matching method, when the vehicle position obtained by a GPS signal or self-contained navigation is from the road L3, it is determined that the vehicle position is on the road L3, and FIG. ), The vehicle position mark is superimposed and displayed on the road L3 on the display target map. In contrast, in the in-vehicle navigation device of the present embodiment, when the navigation controller 1 performs the map matching process to correct the display position of the vehicle position mark on the road position of the map, the information on the road passing history is taken into consideration. Since the display position of the vehicle position mark is determined, the vehicle position mark is superimposed on the road L2 where the vehicle is likely to travel as shown in FIG. Map matching can be performed with high matching accuracy.

  The on-vehicle navigation device described above is an application example of the present invention, and the present invention is not limited to the above example, and various modifications can be made without departing from the technical idea of the present invention. Of course there is. For example, in the above-described example, the road passage history is stored for all the roads through which the vehicle has passed, but the guidance route for guiding the vehicle to the destination is set for writing the road passage history. The road passing history may be stored only for the road set as the guide route. In other words, in-vehicle navigation devices generally have a function of setting a guidance route, and when a guidance route is set, the road set as the guidance route when performing the map matching process is given priority as a matching target. Selected. However, for roads that have been set as guide routes in the past, if the road is used frequently, the driver of the vehicle can reach the destination without setting the guide route. Do not do. In such a case, in the conventional map matching technique, when a road having a guidance route set in the past as a matching candidate in the subsequent map matching processing, the vehicle may be traveling on the road. Even if it is high, the road is treated in the same way as other roads, causing a mismatch. On the other hand, if information on the road passage history is stored for roads for which guidance routes have been set in the past and map matching processing is performed in consideration of this road passage history, roads that have been set as guidance routes in the past. Can be preferentially selected as a matching target and the vehicle position mark can be displayed at the correct position in the same manner as in the state set as the guidance route.

It is a block diagram which shows schematic structure of the vehicle-mounted navigation apparatus to which this invention is applied. In the vehicle-mounted navigation apparatus to which the present invention is applied, it is a flowchart showing a flow of a series of processes by a navigation controller when displaying an image in which a vehicle position mark is superimposed on a map on a display device. It is a figure explaining a mode that a self-vehicle position mark is superimposed and displayed on the road position of a map by map matching processing, (a) is a figure showing the result of map matching processing by the conventional method, (b) shows the present invention. It is a figure which shows the result of the map matching process by the applied vehicle-mounted navigation apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Navigation controller 5 Map data memory | storage device 6 Display apparatus 7 Road passage history memory | storage device 11 Own vehicle position specific part 12 Display control part 13 Map matching process part 14 Road passage history writer

Claims (5)

Map data storage means for storing map data;
Current position detecting means for detecting the current position of the vehicle;
Display means for displaying a vehicle position mark indicating the current position of the vehicle superimposed on a map drawn based on the map data;
Map matching means for correcting the display position of the vehicle position mark on the road position of the map when the current position of the vehicle does not match the road position of the map displayed on the display means;
Road passage history storage means for storing information on roads on which the vehicle has passed in the past as road passage history,
The in-vehicle navigation device, wherein the map matching means determines a display position of the vehicle position mark in consideration of a road passage history stored in the road passage history storage means. The road passage history storage means stores, as the road passage history, information on the number of times the vehicle has passed with respect to the road and the last passage date for each road that the vehicle has passed in the past,
The map matching unit calculates a learning value for the road for each road that is a candidate for the correction position of the vehicle position mark based on the number of times of passage and the last passage date stored in the road passage history storage unit. The vehicle-mounted navigation device according to claim 1, wherein the display position of the vehicle position mark is determined using the calculated learning value. The map matching means calculates the learning value X based on the following formula, where Y is the number of times the vehicle has passed the road and Z is the number of days elapsed from the last passage date to the present. The in-vehicle navigation device according to claim 2.
X = A · Σ (1 / Y) −B · Z (where A is a first coefficient and B is a second coefficient that is smaller than the first coefficient)   The map matching means uses the threshold value as a learning value when the X value calculated by the calculation formula exceeds a predetermined threshold value, and 0 when the X value calculated by the calculation formula is less than 0. The vehicle-mounted navigation device according to claim 3, wherein the learning value is used as a learning value. When the current position of the vehicle is detected and the vehicle position mark indicating the current position of the vehicle is superimposed and displayed on the map drawn based on the map data, the current position of the vehicle is displayed on the map to be displayed. In the map matching method of correcting the display position of the vehicle position mark on the road position of the map when there is a mismatch with the road position,
A map matching method characterized in that information on a road on which a vehicle has passed in the past is stored as a road passage history, and the display position of the vehicle position mark is determined in consideration of the road passage history.

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