JP2008070151A - Current position displaying device, navigation apparatus, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique which prevents any incorrect judgement from being made in a map matching process by considering the quality of map accuracy in an area where a road shape obtained from a road map differs significantly from the actual road shape, and which improves the final accuracy of the current position of a mobile object. <P>SOLUTION: The current position of a vehicle is potentially displayed on a position deviating from a road when travelling on the road in fact, in the case that the map accuracy is poor, and the road shape obtained from the road map differs significantly from the actual road shape (reference Fig.(a)). So, a rating result of the map accuracy of a region around the current position of the vehicle is stored, and then a parameter used for the map matching process is temporarily changed into a value having a large correction range when travelling in the area whose map accuracy is poor. Therefore, any incorrect judgement can be prevented from being made in the map matching process, even in the case that the road shape obtained from the road map differs significantly from the actual road shape (reference Fig.(b)). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for detecting and displaying a current position of a vehicle by executing a map matching process.

  2. Description of the Related Art Conventionally, navigation apparatuses that display a current position of a moving body such as a vehicle together with a road map on a display or set an appropriate route from the current position to a destination and perform route guidance are known.

  In displaying the current position of the moving body and route guidance, it is fundamental to detect the current position of the moving body. For example, in vehicle current position detection, so-called self-contained navigation is known as a basic technique in which the current position is detected by performing dead reckoning calculation based on detection values from a gyroscope or a vehicle speed sensor. However, such a self-contained navigation has a disadvantage that the absolute position cannot be detected. Therefore, using GPS (Global Positioning System) satellites and roadside beacons for positioning, the absolute position, etc. is obtained, and this is added to the results of positioning by self-contained navigation to obtain a more accurate current position. Detection techniques are also known.

  Furthermore, there is a so-called map matching as a technique for correcting the error of the positioning result by these navigations and improving the accuracy of position detection. This is because the travel trajectory to the current position of the vehicle calculated based on the dead reckoning navigation described above (self-contained navigation alone or radio navigation combined with self-contained navigation) is compared with the road shape based on map data, and its correlation The current position of the vehicle is specified on the road based on the above.

As a technique using this type of map matching technique, a technique as described in Patent Document 1 has been proposed. In the technique described in Patent Document 1, erroneous correction is prevented by changing a parameter for determining whether or not to correct the position by map matching according to the road density.
JP 9-304093 A

  By the way, the correction by the map matching process as described above is based on the premise that the road shape obtained from the road map matches the actual road shape. Therefore, when the map accuracy is poor and the road shape obtained from the road map is significantly different from the actual road shape, map matching is not appropriately performed, and the accuracy of determining the current position of the vehicle is lowered. Such regions with low map accuracy include mountainous areas and suburbs. In these areas, it is often not necessary to have a more precise map than in urban areas. Therefore, the accuracy of surveying at the time of map creation is lower than in other areas, or on roads with complicated shapes (for example, mountain roads), a part of the road shape is omitted and the road shape is simplified. It is common. For this reason, an electronic map in which such a road map is stored in a storage medium such as a DVD or a hard disk also includes low-accuracy information whose road shape is greatly different from the actual road map.

  As described above, when the vehicle is traveling in an area where the map accuracy is low, in the map matching process based on the assumption that the road shape obtained from the road map matches the actual road shape, There is a possibility that appropriate map matching is not performed because no correlation is obtained with the road shape obtained from the road map. That is, as shown in FIG. 4 (a), for example, in a road in a region with low map accuracy such as a mountain road, the vehicle is in a sharp curve or the like although it is actually traveling on the road. If the road trajectory does not match the road shape, the vehicle is considered to be traveling outside the road, causing a phenomenon that the current position after the map matching process deviates from the road, and the accuracy of determining the current position decreases. It is.

  In addition, in order to improve the accuracy of determining the current position in an area where the map accuracy is low, the difference between the actual vehicle travel locus and the road shape obtained from the road map is uniformly deviated from the road. If the adjustment is difficult, it is difficult to determine the departure from the road when entering a facility or parking lot in areas with high map accuracy (for example, urban areas). The definite accuracy of is reduced.

  On the other hand, with the technique for changing the parameter for whether or not to correct the position by pattern matching according to the density of the road as described in Patent Document 1, the accuracy of the map is improved by the accuracy of surveying and the simplification of the road shape. The above problem due to pass / fail cannot be solved.

  Therefore, the present invention prevents misjudgment of map matching processing in an area where the road shape obtained from the road map is significantly different from the actual road shape by considering the accuracy of the map accuracy, and the current position of the moving object An object is to provide a technique for improving the accuracy of determination.

  According to the present position display device according to claim 1 made to achieve the above object, the accuracy of a road map in a predetermined geographical range around the current position of a mobile object is evaluated, and the evaluation result is determined as the geography. It is stored in association with the target range. If it is determined that the current position of the moving object falls within a specific range with low map accuracy based on the stored evaluation result, whether or not the current position of the moving object is corrected on the road in the map matching process. The parameter for determining is temporarily changed to a value that makes the correction range larger than a predetermined normal value.

  If the map shape is poor and the road shape obtained from the road map is very different from the actual road shape, there is a high possibility that map matching will not be performed properly. The current position will be displayed at a position off the road. Therefore, in the current position display device of the present invention, the map accuracy around the current position of the mobile object is evaluated, and the evaluation result is stored in association with the geographical range. After that, when traveling on the same road, if it is determined that the current position corresponds to a specific area with low map accuracy based on this stored evaluation result, the parameter used for map matching processing has a large correction range. This problem is solved by temporarily changing the value, that is, a value that makes it difficult to determine that the vehicle has deviated from the road. As a result, even when the road shape obtained from the road map is greatly different from the actual road shape, it is possible to prevent erroneous determination of the map matching process, and the display showing the current position of the moving object is off the road that is passing. It is possible to reduce the inconvenience. In addition, in an area where the map accuracy is good, the map matching process is performed with the above parameters kept at normal values, so that the accuracy of determining the current position of the moving object in the area where the map accuracy is good can be maintained in a good state. In this way, it is possible to realize a current position display device that improves the accuracy of determining the current position of a moving object in an area where map accuracy is low.

  As a method for evaluating the map accuracy around the current position, for example, as shown in claim 2, it is calculated based on the movement trajectory up to the current position of the moving body based on the detection result by the position detection means and the map data. If the degree of match in the geographical range around the current position of the moving object is high, the map accuracy is high, and if the match is low, the map accuracy is low. Can be considered.

  Since the moving trajectory of the moving object is the actual trajectory that has moved along the road, depending on the map accuracy, unlike the map data in which part of the road shape is omitted or simplified, the moving trajectory It is considered to have a high correlation with the road shape. Therefore, if the degree of match between the moving trajectory of the mobile object and the road shape based on the map data is high (or low), the degree of match between the actual road shape and the road shape based on the map data is also high (or low). Conceivable. Therefore, the map accuracy can be evaluated based on the degree of coincidence between the moving locus of the moving object and the road shape based on the map data.

  Furthermore, as shown in claim 3, the map accuracy rating results are cumulatively recorded for each predetermined geographical area, and the weighted evaluation is performed based on the cumulatively stored rating results. You may comprise so that it may determine whether the present position of a moving body corresponds to the specific range with low map precision according to a result. By doing in this way, based on the accumulatively stored evaluation results, an area with low map accuracy can be specified more appropriately, and the accuracy of determining the current position of the mobile object can be improved.

  For example, a point is calculated based on the degree of quality of the map stored in the storage means, the number of evaluations, etc., and according to the value of this point, whether the current position of the moving object falls within a specific range with low map accuracy It may be configured to determine whether or not.

  By the way, the present position display device described above can be configured as a part of a navigation device as shown in claim 4. In the route guidance considering the display of the current position and the relationship between the current position and the route to the destination, if the accuracy of determining the current position can be improved, the effectiveness as a navigation device is improved.

  To realize each means of the map accuracy rating means, the determination means, the parameter setting means, the matching degree calculation means, and the current position specifying means in the current position display device as described above in a computer system, As such, the program may be provided as a program that runs on the computer system. Such a program is recorded on a computer-readable storage medium such as a magnetic disk, a CD-ROM, a hard disk, a ROM, or a RAM, and loaded into the computer as necessary, so that each of the above-described means is used. Functions can be realized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Description of configuration of in-vehicle navigation device 1]
FIG. 1 is a block diagram illustrating a schematic configuration of an in-vehicle navigation device 1 according to the embodiment.

  As shown in FIG. 1, the in-vehicle navigation device 1 is similar to the position detector 21 that detects the current position of the vehicle, the operation switch group 22 for inputting various instructions from the user, and the operation switch group 22. A remote control terminal (hereinafter referred to as a remote controller) 23a capable of inputting various instructions to the remote controller 23b, a remote control sensor 23b for inputting signals from the remote controller 23a, a non-volatile memory 24 for storing various information, and various types of map data, etc. A map data input device 25 for inputting data from an external recording medium in which information is recorded, a display device 26 for performing various displays such as a map display screen, and an audio output device 27 for outputting various guide voices, etc. And a control device 29.

  The position detector 21 receives a radio wave transmitted from an artificial satellite for GPS via a GPS antenna, detects a position of the vehicle, etc., and a detection signal corresponding to the angular velocity of the rotational motion applied to the vehicle. Is provided, and a vehicle speed sensor 21c that outputs a detection signal corresponding to the speed of the vehicle is provided. Each of the sensors 21a to 21c has an error having a different property, and is configured to be used while complementing each other. Depending on the accuracy, a part of the sensors described above may be used, or a steering rotation sensor, a wheel sensor of each rolling wheel, or the like may be used.

The operation switch group 22 includes a touch panel that is integrated with the display device 26 and is installed on the display surface, and a mechanical key switch provided around the display device 26.
The map data input unit 25 reads data from the nonvolatile storage medium based on the control from the control device 29 and inputs the data to the control device 29. The data stored in the nonvolatile storage medium includes the above-described map matching data for improving the position detection accuracy, map data, route guidance data, a program for operating the in-vehicle navigation device 1, and the like. Various data included. As a storage medium for these data, a hard disk, DVD, CD-ROM, memory, memory card, or the like can be used.

  The display device 26 is a color display device having a display surface such as a liquid crystal display. The display device 26 can display various images on the display surface according to the input of the video signal from the control device 29. For example, when the vehicle is traveling, a mark indicating the current location identified from the current position of the vehicle detected by the position detector 21 as the navigation screen and the map data input from the map data input device 25, and guidance to the destination Additional data such as a route, name, landmark, and various landmark symbols are displayed in an overlapping manner.

  The audio output device 27 is configured so that various information can be notified to the user by voice. Thereby, various types of guidance such as route guidance can be given to the user by both the display by the display device 26 and the voice output from the voice output device 27.

  The control device 29 is configured around a known microcomputer including a CPU, a ROM, a RAM, an I / O, a bus line connecting these configurations, and the like, and controls the configuration of each unit described above. The control device 29 executes various processes related to navigation according to a program read from the ROM, the map data input device 25, or the like.

  For example, the navigation-related processing includes map display processing and route guidance processing. The map display process is a process of calculating the current position of the vehicle based on each detection signal from the position detector 21 and displaying a map near the current position read via the map data input unit 25 on the display device 26. is there. The route guidance process is an optimum route from the current position to the destination based on the point data stored in the storage medium and the destination set according to the operation of the operation switch group 22 or the remote controller 23a. This is a process of calculating a destination route and performing travel guidance to the destination in consideration of the relationship between the current position and the destination route. As a method for automatically setting an optimum route in this way, a method such as cost calculation by the Dijkstra method is known.

  Here, a process related to the current position calculation in the map display process and the route guidance process as described above will be described. In the present embodiment, for example, before the vehicle starts to travel, the current position is detected based on positioning information obtained by radio navigation obtained by the GPS receiver 21a, and this position is displayed on the display device 26 so as to be superimposed on the map. To do. When the vehicle starts running, the moving distance of the vehicle is calculated based on the detection signal from the vehicle speed sensor 21c, and the azimuth movement amount is calculated based on the detection signal from the gyroscope 21b. Next, the current position by dead reckoning navigation is calculated based on the calculated moving distance and azimuth moving amount or by adding positioning information by GPS as necessary. Further, based on the calculated movement distance and azimuth movement amount, the travel locus and the vehicle speed of the vehicle are calculated. Then, the calculated current position is corrected by a map matching process, which will be described later, and the corrected current position is displayed on the map displayed on the display device 26 so as to be identifiable using a mark indicating the traveling direction of the vehicle.

  Correction by map matching is used to determine the degree of match (approximate degree) between the travel locus to the current position of the vehicle calculated by dead reckoning and the road shape (road pattern) based on the map data, and whether the current position can be corrected. Comparison is made with a parameter indicating the correction range. When the degree of match is within the correction range indicated by the parameter, the position closest to the current position calculated by dead reckoning navigation on the road is specified as the current position of the vehicle. Alternatively, when the degree of match is not within the correction range indicated by the parameter, the current position calculated by dead reckoning navigation is directly specified as the current position of the vehicle.

  It should be noted that the degree of coincidence between the travel locus by dead reckoning and the road shape based on the map data is calculated as follows. For example, the travel trajectory and the road shape are each decomposed into vectors for each predetermined distance, the azimuth difference between the travel trajectory vector and the road vector is calculated as an average value for each predetermined interval, and the degree of match is determined based on the magnitude of the average value. . That is, if the average value of the azimuth difference between the travel locus vector and the road vector is large, the degree of match is small because the difference between the travel locus and the road shape is large. On the contrary, if the average value of the azimuth difference between the travel locus vector and the road vector is small, the difference between the travel locus and the road shape is small, and the degree of coincidence is large.

  In the present embodiment, the accuracy of the map in the area around the current position of the vehicle is evaluated based on the degree of coincidence between the travel locus by dead reckoning calculated by the method as described above and the road shape based on the map data. The result is stored in the nonvolatile memory 24 in association with the road or area. After that, when traveling on the road or area again, if it is determined that the map accuracy in the area around the current position is low based on the stored map accuracy evaluation results, the map matching parameters described above are The value is temporarily changed from a predetermined normal value to a value that increases the correction range (that is, a value that facilitates matching on the road). As a result, while traveling on a road in an area with low map accuracy such as a mountainous area, the current position can be made difficult to deviate from the road. A detailed description of this series of processing will be described later.

  The schematic configuration of the in-vehicle navigation device 1 has been described above, but the correspondence between the configuration of the in-vehicle navigation device 1 in the present embodiment and the configuration described in the claims is as follows. The position detector 21 of the vehicle-mounted navigation device 1 according to the present embodiment corresponds to the position detection means in the claims. Further, the map data input device 25 corresponds to a map storage means. The nonvolatile memory 24 corresponds to a storage unit. The display device 26 corresponds to a map display unit. The control device 29 corresponds to map accuracy rating means, determination means, parameter setting means, matching degree calculation means, and current position specifying means.

Hereinafter, each process related to the current position calculation executed by the control device 29 of the vehicle-mounted navigation device 1 will be described with reference to the flowcharts of FIGS.
[Explanation of map accuracy rating process]
FIG. 2 is a flowchart showing the procedure of “map accuracy rating process” executed by the control device 29 of the vehicle-mounted navigation device 1. This “map accuracy rating process” is a process that is executed every predetermined time or every time the vehicle travels a predetermined distance after the in-vehicle navigation device 1 is activated.

  When the “map accuracy rating process” is started, the control device 29 first calculates the degree of coincidence between the travel locus by dead reckoning navigation in a predetermined range around the current position and the road shape based on the map data of the road on which the vehicle is traveling ( Step 110. Hereinafter, the step is simply indicated by the symbol S). As for the method of calculating the degree of coincidence, for example, the traveling trajectory and the road pattern are each decomposed into vectors for each predetermined distance, and the azimuth difference between each traveling trajectory vector and the road vector is calculated as an average value for each predetermined interval. The degree of match is determined by the magnitude of the value.

  Next, it is determined whether or not the calculated degree of match is equal to or less than a predetermined reference value (S120). Here, when it is determined that the degree of coincidence is equal to or less than a predetermined reference value (S120: YES), that is, when the coincidence between the travel locus by dead reckoning navigation and the pattern of the road being traveled is low, the corresponding road (or The area in the predetermined range is registered as an area with a low map accuracy (hereinafter referred to as a low accuracy area) (S130), and the “map accuracy rating process” is terminated. Specifically, data in which low-accuracy information is given to the ID for specifying the road data or the coordinates on the map indicating the area is stored in the nonvolatile memory 24. Alternatively, each time the vehicle travels a plurality of times in the same region, the calculation result of the degree of match in the region may be cumulatively stored in the nonvolatile memory 24.

  On the other hand, if it is determined in S120 that the degree of match is greater than the predetermined reference value (S120: NO), that is, if the coincidence between the travel locus by dead reckoning navigation and the pattern of the road being traveled is high, the “map accuracy rating is performed as it is. The process is terminated.

[Description of current location identification processing]
Next, FIG. 3 is a flowchart showing a procedure of “current position specifying process” executed by the control device 29 of the vehicle-mounted navigation device 1. The “current position specifying process” is a process that is executed every predetermined time during the traveling of the vehicle or every time the vehicle travels a predetermined distance.

  When the “current position specifying process” is started, the control device 29 first refers to the map accuracy rating result data stored in the non-volatile memory 24, and the road (or region) currently being traveled is the above-mentioned low accuracy. It is determined whether it corresponds to an area (S210). Specifically, it is determined whether low-accuracy information is given to the ID of road data currently being traveled or coordinates indicating the area. Or, if the calculation results of the degree of match in the area are cumulatively stored, points are calculated based on the degree of match and the number of evaluations, etc., and the road (or area) that is currently running according to the value of this point ) May correspond to a low-accuracy region.

  When it is determined in S210 that the road (or region) currently running corresponds to the above-described low-accuracy region (S210: YES), the map matching parameter is a value that increases the correction range from a predetermined normal value ( That is, the value is temporarily changed to a value that facilitates matching on the road (S220). Then, using this parameter, the current position is specified by the map matching process described above (S230), and the “current position specifying process” is terminated.

  On the other hand, when it is determined in S210 that the road (or region) currently being traveled does not correspond to the above-described low-accuracy region (S210: NO), the current position is identified by the above-described map matching process using the normal value parameter. (S230), “current position specifying process” is terminated.

[effect]
According to the vehicle-mounted navigation device 1 of the above embodiment, the following effects can be obtained.
If the road shape obtained from the road map is very different from the actual road shape due to poor map accuracy, there is a high possibility that map matching will not be performed properly in the past. The current position of the vehicle will be displayed at a position off the road (see FIG. 4A). Therefore, in the present embodiment, the map accuracy evaluation result around the current position of the vehicle is stored in association with the road or the area, and then the map matching process is performed when the current position travels in the low accuracy area. The parameter used for is temporarily changed to a value that increases the correction range.

  As a result, as shown in FIG. 4B, even when the road shape obtained from the road map and the actual road shape are significantly different, erroneous determination of the map matching process can be prevented, and the current position of the vehicle is indicated. It is possible to reduce the inconvenience that the display deviates from the passing road. In addition, in an area where the map accuracy is good, the map matching process is performed with the above parameters kept at normal values, so that the accuracy of determining the current position of the vehicle in the area where the map accuracy is good can be maintained in a good state. If the accuracy of determining the current position can be improved in the route guidance considering the display of the current position and the relationship between the current position and the route to the destination, the effectiveness as a navigation device is improved.

As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment at all, It is possible to implement in various aspects.
For example, although the above-described embodiment implements the present invention as the vehicle-mounted navigation device 1, it can also be applied to a device that executes processes other than navigation using the specified current position.

  In the above embodiment, when detecting the current position, the current position and traveling direction of the vehicle are calculated based on the detection signal from the GPS receiver 21a in addition to the gyroscope 21b and the vehicle speed sensor 21c. What is necessary is just to be able to calculate the current position and the traveling direction of the vehicle based on the detection signals from the gyroscope 21b and the vehicle speed sensor 21c.

It is a block diagram showing a schematic structure of in-vehicle navigation device 1 of an embodiment. It is a flowchart which shows the procedure of the "map accuracy rating process" which the control apparatus 29 of the vehicle-mounted navigation apparatus 1 performs. It is a flowchart which shows the procedure of the "current position specific process" which the control apparatus 29 of the vehicle-mounted navigation apparatus 1 performs. It is explanatory drawing which shows typically the driving | running | working locus | trajectory of the vehicle by dead reckoning navigation on the road of a mountainous area, and the present position of the vehicle after map matching.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vehicle-mounted navigation apparatus, 21 ... Position detector, 22 ... Operation switch group 22, 23a ... Remote control terminal (remote control), 23b ... Remote control sensor, 25 ... Map data input device, 25a ... Map database, 25b ... Address database 25c ... polygon database, 26 ... display device, 27 ... audio output device, 29 ... control device.

Claims (5)

Map storage means for storing the converted road map;
Position detecting means for detecting the current position of the moving body;
Storage means for storing information relating to the accuracy of the road map;
A map accuracy rating unit that evaluates the accuracy of the road map in a predetermined geographical range around the current position of the moving object, and records the rating result in the storage unit in association with the geographical range;
A determination unit that determines whether or not the geographical range corresponding to the current position of the mobile body is a specific range having a low map accuracy, based on a map accuracy evaluation result stored in the storage unit;
When the determination unit determines that the geographical range corresponding to the current position of the moving body is the specific range, a correction range for determining whether or not to correct the current position of the moving body on the road is shown. Parameter setting means for temporarily changing the parameter to a value that makes the correction range larger than a predetermined normal value;
The degree of coincidence calculation for calculating the degree of coincidence between the movement trajectory up to the current position of the moving body based on the detection result by the position detection unit and the road shape based on the map data stored in the map storage unit for each predetermined distance Means,
When the degree of coincidence calculated by the degree of coincidence calculation means is within the correction range indicated by the parameter, the current position of the moving body is a predetermined position on the corresponding road in the road map stored in the map storage means. A current position specifying means for performing a map matching process to correct the current position of the moving body,
Map display means for reading out and displaying a road map around the current position of the moving object specified by the current position specifying means from the map storage means, and displaying the current position of the moving object on the road map so as to be identifiable. A current position display device characterized by comprising: In the present position display device according to claim 1,
The map accuracy rating means, based on the match degree calculated by the match degree calculation means, evaluates that the map accuracy is high when the match degree in a predetermined geographical range around the current position of the moving object is high, A current position display device characterized in that when the degree of match is low, the map accuracy is evaluated as low. In the present position display device according to claim 1 or 2,
The map accuracy rating means cumulatively records the rating results for each of the predetermined geographical ranges in the storage means,
The determination unit performs weighted evaluation based on the rating result corresponding to the geographical range stored in the storage unit, and the geographical range corresponding to the current position of the moving object is determined according to the result of the weighted evaluation. It is determined whether it is the said specific range. The present position display apparatus characterized by these. A current position display device according to any one of claims 1 to 3,
On the road map displayed on the map display means, the route to the destination set in advance and the current position of the moving body specified by the current position specifying means are displayed so as to be identifiable, and the route to the destination A navigation device that performs predetermined route guidance in consideration of a relationship with a current position of a mobile object.   A program for controlling a computer used as the current position display device according to any one of claims 1 to 3, wherein the computer is used as the map accuracy rating means in the current position display device, the determination means, A program for functioning as the parameter setting means, the degree-of-match calculation means, and the current position specifying means.