JP2010043938A - Present position calculating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a present position calculating device capable of accurately calculating the present location. <P>SOLUTION: When a display candidate point belongs to a road after branching, and road height information is added to a link corresponding to the road after branch, it is determined which of the roads after branching is used for traveling, based on the road height information and displacement (vehicle height displacement) in the vehicle height direction detected by an acceleration sensor 11b of the vehicle, prior to the calculation of reliability "trst". <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a current position calculation device that calculates a current position.

  There is known a current position calculation device that corrects a current position of a vehicle by performing a map matching process when calculating the current position of the vehicle. In this current position calculation device, when the map matching process is performed, the current position calculation device is currently traveling on a road where the difference between the detected traveling direction of the vehicle and the extending direction of the road stored as data is a predetermined value or less. The candidate is selected as a road candidate (see Patent Document 1).

JP-A-8-334371

  The road data includes information about the extending direction as described above. For example, the road branch from one road to the main road and the side road (branch), the entrance of the expressway, In the branching portion at the exit, there may be a large difference between the actual branching direction and the data extending direction. Therefore, if the map matching process is performed during the traveling of the branch portion, it may be determined that the vehicle is traveling on a road different from the road on which the vehicle is actually traveling.

(1) The present position calculation device according to the invention of claim 1 is located on any of the branched roads other than the information related to the extending direction of the road when the road is branched forward in the traveling direction. When determining whether the vehicle is located on the branch road or the presence / absence determination means for determining the presence / absence of information (branch path determination information) for determining whether there is a road before reaching the branch point of the road If the presence / absence determination means determines that the branch road determination information exists, the branch determination information is determined only by the determination based on the branch road determination information, and the branch determination information is determined by the presence / absence determination means. If it is determined that the position does not exist, the current position is determined on the basis of the determination result of the position determination means that determines where the road is branched without using the branch road determination information, and the determination result of the position determination means. presume And a current position estimating means.
(2) In the present invention of claim 2, in the current position calculation device according to claim 1, the position determination means includes a plurality of branch path determination information of different types for a branched road. Based on the branch path judgment information judged to have the highest credibility among the branch road judgment information, the branch that is judged to be located on the branched road is judged to have the highest credibility. When a road to be traveled is specified based on the road determination information, other branch road determination information is not used.
(3) The present invention according to claim 3 is the current position calculation device according to claim 1 or claim 2, wherein the branch road determination information includes information on the height of the road.
(4) According to a fourth aspect of the present invention, in the current position calculation device according to the third aspect, the position determination means obtains information related to a change in the height position of the vehicle with traveling, and includes information related to the height of the road. By comparing, it is determined which of the branched roads is located.

  According to the present invention, the current position can be calculated correctly.

  With reference to FIGS. 1 to 7, an embodiment in which a current position calculation device according to the present invention is applied to a car navigation device for in-vehicle use will be described. FIG. 1 is a diagram showing an overall configuration of the car navigation apparatus according to the present embodiment. The car navigation device 1 relates to vehicle travel, such as a function for displaying a road map around a vehicle position, a function for calculating a recommended route from a departure place to a destination, and a function for performing route guidance based on the calculated recommended route. It also has a function to present information. The car navigation device 1 is a device that performs so-called navigation or road guidance.

  In FIG. 1, reference numeral 11 denotes a current position detection device that detects the current position of the vehicle. For example, a gyro sensor 11 a that detects a change in the traveling direction of the vehicle, an acceleration sensor 11 b that detects displacement in the height direction of the vehicle, and GPS (Global Positioning System) The GPS sensor 11c detects a GPS signal from a satellite, the vehicle speed sensor 11d detects a vehicle speed, and the like.

  Reference numeral 100 denotes a control device, which includes a CPU 101 and its peripheral circuits. The CPU 101 and its peripheral circuits are connected to each other via a bus. The peripheral circuit includes a memory 102, a parallel I / O 103, A / D converters 104a and 104b, a serial I / O 105, a counter 106, a graphic controller 107, an image memory 108, a map storage device 109, and the like. Reference numeral 14 denotes a display monitor which is disposed at a position where a passenger in the vehicle can visually recognize and displays a map and various types of information. Reference numeral 15 denotes a switch for an occupant to input various operations such as input of a destination of the vehicle. The switch 15 includes a touch panel switch provided on the screen of the display monitor 14 and a joystick for instructing movement of the cursor or scrolling of the screen. The switch 15 may be a remote control switch or a switch provided around the display screen.

  The memory 102 of the control device 100 is a memory including a ROM for storing a control program and a RAM for a work area. The CPU 101 accesses the memory 102, executes a control program, and performs various controls. The parallel I / O 103 is a parallel I / O port to which individual switches constituting the switch 15 are connected. The A / D converters 104a and 104b are converters that A / D convert analog signals of the gyro sensor 11a and the acceleration sensor 11b, respectively. The serial I / O 105 is a serial I / O port that receives a serial signal from the GPS sensor 11c. The counter 106 is, for example, a counter that counts pulse signals output from the vehicle speed sensor 11d as the axle rotates.

  The graphic controller 107 stores display data output from the CPU 101 as image data in a memory 108 that is an image memory (video RAM), and performs control for displaying the image data stored in the memory 108 on the display monitor 14. Do. The display data output from the CPU 101 includes various character data and various graphic data such as a road map. The control device 100 functions as a display control device for the display monitor 14.

  The map storage device 109 is a map storage device that stores various types of information such as road map data and POI information (point of interest sightseeing spots and various facilities information) used for navigation processing, and uses a hard disk device. In addition to the hard disk device, the map storage device 109 may be a CD-ROM or DVD storing road map data, other recording media, and a reading device thereof.

--- Data structure ---
The road map data is information relating to the map, and includes map display data, route search data, guidance data (intersection name / road name / direction name / direction guide facility information, etc.) and the like. The map display data is data for displaying the road and the background of the road map. The route search data is data including branch information that is not directly related to the road shape, and is mainly used when calculating (route search) a recommended route. The guidance data is data including names of intersections and the like, and is used when the recommended route is guided to the driver or the like based on the calculated recommended route.

  FIGS. 2A and 2B are diagrams showing the configuration of map display data (road data). The road data includes link string data and mesh codes, and is stored in units of mesh areas. The link string data is a data structure in which one road is defined as a node such as an intersection and a link between the nodes. The mesh area refers to each divided area when the road map is divided into predetermined ranges. The mesh code storage area 401 stores a number for identifying the mesh area. In the link string data storage area 402, as shown in FIG. 2B, the position coordinates Xn, Yn of the node, the number of the link between the nodes, and the position coordinates Xn, Yn is stored in each area. These position coordinates are used as shape data for map display and current position calculation processing described later. Although not shown, for example, for roads (such as ramps) connecting adjacent roads having different heights, or inclined roads, the road map data is high every predetermined distance (for example, every several meters). The data (road height information) is stored in units of several tens of centimeters, for example.

  The car navigation device 1 configured as described above performs various types of navigation based on information acquired by the current location detection device 11 and road map data stored in the map storage device 109. For example, the CPU 101 of the control device 100 displays a road map near the current position of the vehicle and the current position of the vehicle on the display monitor 14 so as to guide the driver along the route (recommended route) obtained by the route search. Control each part.

--- Current position calculation process ---
In order to display the current position of the vehicle in a superimposed manner on the road map near the current position displayed on the display monitor 14, the car navigation device 1 according to the present embodiment calculates the current position by the following process. . FIG. 3 is a flowchart showing the operation of the current position calculation process. When the accessory ON (ACC ON) is turned on by an ignition key (not shown) of the vehicle, the car navigation device 1 is turned on, and a program for performing the processing shown in FIG. 3 is periodically started.

  The CPU 101 reads data from the gyro sensor 11a and the vehicle speed sensor 11d (step S1), and determines whether or not the vehicle is traveling straight on the basis of the read data (step S3). If it is determined that the vehicle is traveling straight (Yes in step S3), the moving amount of the vehicle is calculated by calculating the traveling direction of the vehicle and the traveling distance of the vehicle based on the read data. Then, starting from the current position of the vehicle calculated last time, a point estimated to be present is calculated by adding the movement amount of the vehicle calculated this time (step S5). This point is the estimated current position.

  Note that, for example, immediately after the car navigation device 1 is started, the current position of the vehicle calculated and stored immediately before the car navigation device 1 is stopped last time, or the current position of the vehicle that was previously calculated from a previously set point. The above processing is performed.

After calculating the estimated current position as described above, a current position candidate is calculated as follows. The CPU 101 searches for and extracts links (candidate links) satisfying both of the following (a) and (b) from the road data stored in the map storage device 109 (step S7).
(A) The difference between the travel direction of the vehicle calculated when calculating the estimated current position and the link direction (link direction) of the road data is equal to or less than a predetermined value.
(B) The length of the line segment dropped from the estimated current position perpendicularly to the link is not more than a predetermined value.

  It is determined whether or not the above-described candidate link exists, and if it is determined (Yes in step S9), the vehicle current calculated in the previous process is calculated by the vehicle travel distance calculated when calculating the estimated current position. A point moved from the position along the link is set as a candidate for the current position (step S11). The current position candidate obtained in this way is called a display candidate point. When it is determined that there is no link satisfying the above-described (a) and (b) (No at Step S9), a dead reckoning process (Step S19) described later is executed.

  When a link to which a plurality of display candidate points obtained by the above-described processing belongs is traced forward (for example, about 100 m to 300 m ahead from the display candidate point) toward the traveling direction side of the vehicle, two or more links are obtained. It is determined whether or not it is branched (step S21). When branching to two or more links (step S21: affirmative determination), 1 is set to the flag of each of the branched links, and the following processing is performed. On the other hand, when it is determined that there is no branched link (No at step S21), the following processing is performed without setting the flag.

  For convenience of explanation, as shown in FIG. 4, when the link to which the display candidate point belongs is traced forward toward the vehicle traveling direction side (links a1, a2, a3,... The individual links b1, b2, b3... Are called branch links. These individual branch links are collectively referred to as a branch link group. In addition, individual branch links (for example, links a1 and a3) belonging to the same branch as one arbitrary branch link (for example, link a2) are referred to as branch branch links, respectively, and the branch branch links are grouped together. Call it. Individual branch links (for example, links b1 to b3) that belong to a branch different from any one branch link (for example, link a2) are referred to as different branch links, and the individual branch links are grouped into different branches. This is called a link group.

  In the above-described processing, since a plurality of candidate links and display candidate points are extracted, the reliability trst representing the certainty (credibility) as the road on which the vehicle is actually traveling is calculated for each display candidate point. (Step S13 in FIG. 3). The calculation process of the reliability trst will be described in detail later. When the reliability trst is calculated for each display candidate point, the display candidate point with the highest reliability trst is selected (step S15). Then, the selected display candidate point is displayed on the display monitor 14 together with the surrounding road map as the current position of the vehicle (step S17). In this way, the process of extracting the candidate link and determining the display candidate point having the highest reliability trst as the current position of the vehicle is generally called map matching. In addition to the display candidate point having the highest reliability trst, the position of the display candidate point other than the display candidate point having the highest reliability trst is also stored, and the estimated current position of the display candidate point is next processed. The reliability trst is calculated as a starting point for the calculation.

  After reading the data from the gyro sensor 11a and the vehicle speed sensor 11d (Step S1), when it is determined that the vehicle is turning (No at Step S3), or the above (a) and (b) are satisfied. When it is determined that there is no link (No at Step S9), a known dead reckoning process is performed (Step S19). That is, the moving amount of the vehicle is calculated by calculating the traveling direction of the vehicle and the traveling distance of the vehicle based on the read data. Then, a point obtained by adding the currently calculated amount of movement of the vehicle to the previously calculated current position of the vehicle is set as the current position of the vehicle (step S19), and is superimposed on the display monitor 14 along with the surrounding road map. (Step S17).

--- About calculation of reliability trst ---
The reliability trst is the absolute value (azimuth difference) Δθ of the difference between the calculated traveling direction of the vehicle and the link direction of the road data, and the length of the line segment dropped from the estimated current position perpendicular to the candidate link It is calculated based on the length (perpendicular distance) L. Specifically, it is calculated as follows. The link orientation is calculated by reading the position coordinates of the nodes located at both ends of the link from the link area data storage area 402 of the road data shown in FIG.

The error cost value ec defined by the equation (1) is calculated from the azimuth difference Δθ and the perpendicular distance L.
ec = α × Δθ + β × L (1)
In the equation (1), α and β are coefficients.

Next, the accumulated error cost es is calculated. The accumulated error cost es is calculated as follows based on the accumulated error cost es _n−1 calculated in the previous process and the currently calculated error cost value ec.
es = (1−k) × es _n−1 + k × ec (2)
Here, k is a weighting factor. The accumulated error cost es is a value obtained by reflecting the accumulated error cost es _n−1 calculated in the previous process on the error cost calculated in the current process.

The smaller the azimuth difference Δθ and the shorter the perpendicular distance L, the closer to zero the error cost value ec and the accumulated error cost es determined by the equations (1) and (2). That is, the higher the credibility as the actual vehicle position is, the closer the error cost value ec and the accumulated error cost es obtained by the equations (1) and (2) approach to zero. However, since the higher the reliability as the actual vehicle position, the easier it is to understand that the value of the reliability trst increases, the reliability trst is defined by equation (3).
trst = 100 / (1 + es) (3)
Accordingly, the reliability trst value approaches 100 as the reliability as the actual vehicle position increases, and the reliability trst approaches 0 as the reliability as the actual vehicle position decreases.

--- Conventional problems in calculation of reliability trst ---
As described above, the reliability trst is calculated based on the traveling direction and traveling distance of the vehicle calculated by the traveling of the vehicle and the road data. Therefore, for example, as shown in FIGS. 5 (a) and 5 (b), the general road and the highway extend at different height positions, but the general road and the highway are adjacent to each other on the plane and are substantially the same. If it extends in the direction, even if you drive on the ramp and enter the expressway, the amount of change in the direction of travel of the vehicle is small, so a display (car mark) that shows the current position of the vehicle is displayed on the general road It may continue. Conversely, the vehicle fluctuates left and right by the driver's handle operation in front of the ramp, and the gyro sensor 11a detects the fluctuation of the vehicle, so that it is determined that the vehicle has entered the ramp despite continuing on the general road. As a result, the car mark may be erroneously displayed on the lamp.

  For example, at Eifuku entrance on the Tokyo Metropolitan Expressway No. 4 Shinjuku Line down line side, a ramp entering the No. 4 Shinjuku Line from National Route 20 is provided on the down right lane side of National Route 20. The ramp is connected to the elevated No. 4 Shinjuku line while curving gently to the right, but the national highway No. 20 and the elevated No. 4 Shinjuku line under the ramp are also gently curved to the right. Yes. In such a place, even if it is detected by the gyro sensor 11a that the vehicle is traveling while curving to the right, it is accurately determined whether the vehicle has entered the ramp or is traveling on the national highway No. 20. Is difficult.

  Further, even if the vehicle runs on a ramp from the expressway and gets off to a general road, the car mark may continue to be displayed on the expressway because the amount of change in the traveling direction of the vehicle is small. On the contrary, the vehicle fluctuates left and right by the driver's handle operation in front of the ramp, and the gyro sensor 11a detects the fluctuation of the vehicle, so that it is determined that the vehicle has entered the ramp despite continuing on the highway. As a result, the car mark may be erroneously displayed on the lamp.

  Further, for example, as shown in FIGS. 5 (a) and 5 (b), when a general road travels from the left side to the right side in the drawing, the ramp gently branches off from the general road, and the ramp is abbreviated as a general road below the ramp. On a parallel road, the azimuth direction of the lane that branches off from the general road to the ramp and the link azimuth of the link that corresponds to the lane of the part that diverges from the general road to the ramp (branch) are greatly different There is. Thus, if the actual road extension direction and the link direction are greatly different in the vicinity of the branch point, there is a high possibility that the current position of the vehicle is erroneously calculated.

When the general road after the branch and the expressway are substantially parallel, as will be described below, the current position of the vehicle may continue to be calculated as being on the wrong road. That is, when the general road after the branch and the highway are substantially parallel, the link directions for the general road and the highway are substantially parallel, so the difference between each link direction and the traveling direction of the vehicle is approximately It becomes equal, and the difference of the error cost value ec between the general road and the expressway becomes small. However, since the accumulated error cost es _n−1 calculated in the previous process is reflected in the accumulated error cost es, the display candidate point on the road that has been determined as the current position in the previous process also in this process. The reliability trst is higher than the reliability trst of the display candidate point on the road that has not been determined as the current position last time. For this reason, the display candidate point on the road that has been previously determined as the current position is determined as the current position of the vehicle. If the ordinary road and the expressway extend side by side even if they turn left and right, that is, if there is no significant difference between the shape of the ordinary road and the shape of the expressway, If the current position of the vehicle is calculated as being on the wrong road, the error will not be corrected.

--- Calculation of reliability in the present embodiment ---
On the other hand, as shown in FIGS. 5 (a) and 5 (b), even when a general road and a highway having different road heights extend in substantially the same direction, the ramp portion is inclined. The angle is clearly different from ordinary and highways. In general, since the distance of the lamp part is rarely longer than necessary due to the construction cost and the land securing, the inclination angle of the lamp part becomes larger. This tendency is particularly prominent in urban areas. Also, especially in urban areas, due to the difficulty in securing land, highways are often installed on conventional highways, so highways and highways with different road heights are often used. In many cases, the road extends in substantially the same direction. Therefore, for example, when determining whether the vehicle is traveling on a general road or an expressway as shown in FIGS. 5A and 5B, the reliability trst based on the azimuth difference Δθ and the perpendicular distance L is used. The determination accuracy is higher when the determination is made based on the road height information and the displacement in the vehicle height direction detected by the vehicle acceleration sensor 11b than the determination.

  Therefore, when the display candidate point belongs to the road after branching and road height information is added to the link corresponding to the road after branching, the CPU 101 calculates the reliability trst, Based on the road height information and the displacement in the height direction of the vehicle (vehicle height displacement) detected by the vehicle acceleration sensor 11b, it is determined which road after the branch is traveling.

  That is, in the car navigation device 1 according to the present embodiment, if the road on which the vehicle is traveling can be determined based on the road height information and the vehicle height displacement, It is determined which road the vehicle is traveling on after taking into account only the height information and the vehicle height displacement. In the determination, other determination factors such as the azimuth difference Δθ and the perpendicular distance L are not considered. In this case, for example, the reliability trst has a higher value for the display candidate points on the recommended route than the display candidate points other than the recommended route so that the car mark is easily displayed on the recommended route. Even if it is set to, such setting is invalid and it is determined which road the vehicle is traveling on after branching. In the car navigation device 1 according to the present embodiment, the road height information is information other than information related to the extending direction of the road, and information for determining which of the branched road is located (branch road) Used as judgment information).

  Based on the road height information and vehicle height displacement, if it is possible to determine which road the vehicle is traveling on after branching, it is on the link of the road that was not determined to be traveling The existing display candidate point is set to the maximum value (or a predetermined value) that can take the value of the accumulated error cost es. As for the display candidate points existing on the link of the road determined to be traveling, the error cost value ec and the accumulated error cost es are calculated as described above. By doing in this way, the reliability of the display candidate point that exists on the link of the road that has not been determined to be traveling is as close to 0 as possible and the one that has not been determined to be traveling The display candidate point existing on the road link is prevented from being erroneously calculated as the current position of the vehicle.

  If it is not possible to determine which road the vehicle has been branched on based on the road height information and the vehicle height displacement, the CPU 101 sets the azimuth difference Δθ and the perpendicular distance L as usual. Based on this, the reliability trst is calculated.

  Specifically, in the car navigation device 1 of the present embodiment, the reliability trst is calculated by the following process. FIG. 6 is a reliability calculation subroutine (step S13 in FIG. 3) in the flowchart showing the operation of the current position calculation process described above. The CPU 101 selects any one of the calculated display candidate points after setting the flag as described above (step S23) or after calculating the display candidate points (negative determination in step S21 in FIG. 3) ( Step S131). In the following description, the selected display candidate point is referred to as a selection display candidate point. And it is judged whether 1 is set to the flag of the link to which the selection display candidate point belongs (step S133). That is, it is determined whether or not the link to which the selection display candidate point belongs is a link (that is, a branch link) determined to be a branched link in step S21 of FIG.

  When 1 is set in the flag of the link to which the selection display candidate point belongs, that is, when the link to which the selection display candidate point belongs is a branch link (Yes in step S133), the branch link and the branch link It is determined whether or not road height information is added to both the branch branch links (step S151). When the road height information is added (Yes in step S151), the road height information and information related to the displacement in the height direction of the vehicle detected by the vehicle acceleration sensor 11b are acquired (step S153). ). Thereafter, the height position of the road at the display candidate point is calculated for each of the selected display candidate point and the display candidate point on the different branch link with respect to the branch link to which the selected display candidate point belongs.

  Then, the calculated height position is compared with the height position calculated at the previous calculation, and the displacement of the height position of the display candidate point from the previous calculation to the current calculation is calculated (step). S155). That is, how much the road height has changed is calculated. For example, as shown in FIGS. 7A and 7B, a case where the vehicle travels in the vicinity of a ramp on a general road to which the ramp is connected will be described. For example, let us consider a case where the display candidate point at the time of the previous calculation is before the entrance of the lamp, and the display candidate point at the time of the current calculation is on the lamp and on the general road that has passed the lamp entrance. First, the road height difference Δhr between the display candidate point at the previous calculation and the display candidate point on the lamp at the current calculation, the display candidate point at the previous calculation and the current calculation time A difference in road height Δhd from the display candidate points on the general road is calculated.

  Since the road height at the display candidate point is stored for each predetermined distance as road height information as described above, it is obtained by appropriately interpolating from the road height information at positions before and after the display candidate point. For example, when road height information exists only in the ramp, the road height of the general road may be calculated as being equal to the road height at the ramp entrance.

  Thus, in addition to calculating the displacement of the height position of the display candidate point, information on the displacement in the height direction of the vehicle acquired at the previous calculation, and information on the displacement in the height direction of the vehicle acquired at the current calculation Based on the above, the vehicle height displacement from the previous calculation to the current calculation is calculated (step 157). The displacement in the height direction of the vehicle can be obtained by performing time integration twice on the acceleration in the height direction of the vehicle detected by the acceleration sensor 11b between the previous calculation time and the current calculation time. For example, as shown in FIG. 7A, when the position of the vehicle at the previous calculation is in front of the entrance of the ramp and the position of the vehicle at the current calculation is on the ramp, the displacement in the height direction of the vehicle Is a displacement corresponding to Δhc in the figure. Further, as shown in FIG. 7B, when the position of the vehicle at the time of the current calculation is on a general road, the displacement in the height direction of the vehicle is a displacement corresponding to Δhd in the figure.

  Compare the displacement of the height position of the display candidate point and the displacement of the vehicle height from the previous calculation time to the current calculation time, and whether the vehicle exists on the link to which the selection display candidate point belongs, It is determined whether the link exists on the branch branch link (step S159). For example, the difference between the displacement of the height position of the display candidate point and the displacement of the vehicle height for the branch link to which the selected display candidate point belongs is within a predetermined value, and the height of the display candidate point for the different branch branch link When the difference between the displacement of the position and the displacement of the vehicle height exceeds a predetermined value, it is determined that the vehicle exists on the branch link to which the selection display candidate point belongs. On the contrary, the difference between the height position displacement of the display candidate point and the vehicle height displacement for the branch link to which the selected display candidate point belongs exceeds a predetermined value, and the height of the display candidate point for the different branch branch link If the difference between the displacement of the position and the displacement of the vehicle height is within a predetermined value, it is determined that the vehicle exists on the bifurcated branch link. The difference between the displacement of the height position of the display candidate point for the branch link to which the selected display candidate point belongs and the displacement of the vehicle height, and the displacement of the height position of the display candidate point for the different branch branch link If both of the difference from the displacement of the vehicle height are within the predetermined value or exceed the predetermined value, whether the vehicle exists on the branch link to which the selection display candidate point belongs, Does not (cannot) determine if it exists above.

  When it is possible to determine whether the vehicle exists on the branch link to which the selection display candidate point belongs or on the different branch branch link (Yes in step S159), the vehicle is present. The maximum value (or a predetermined value) that can be taken as the cumulative error cost es of the display candidate point belonging to the link that has not been determined is set, and the reliability trst for this display candidate point is described above. Calculation is performed using equation (3) (step S161).

  Then, the error cost value ec and the accumulated error cost es of the display candidate points belonging to the link on which the vehicle is determined to exist are calculated using the above-described equations (1) and (2), and this display is performed. The reliability trst for the candidate point is calculated by the above-described equation (3) (step S163). Thereafter, 0 is set to the flag of each link of the same-branch link group and the different-branch link group of the link to which the selection display candidate point belongs in this calculation (step S165).

  When it is determined that 0 is set in the flag of the link to which the selection display candidate point belongs (No in step S133), the link is different from the case where it is determined that 1 is set in the flag. Without reading the road height information, the error cost value ec, the accumulated error cost es, and the reliability trst are calculated by the above-described equations (1) to (3) (step S143). The same applies when there is no road height information for the link (No at step S151) (step S143). In addition, the displacement of the height position of the display candidate point from the previous calculation time to the current calculation time is compared with the displacement of the vehicle height, and the vehicle exists on the branch link to which the selected display candidate point belongs. The same applies to the case where it is not possible to determine whether or not the link exists on the branch branch link (step S143).

  The above-described processing is sequentially executed for all display candidate points (No determination in step S141). When the reliability trst is calculated for all the display candidate points (Yes in step S141), the process in the reliability calculation subroutine is terminated, and the process returns to the main routine (step S15 in FIG. 3).

The car navigation device 1 described above has the following operational effects.
(1) Considering only the road height information and the vehicle height displacement if it is possible to determine which road the vehicle is traveling on the basis of the road height information and the vehicle height displacement. Thus, it is configured to determine which road the vehicle is traveling on after branching. As a result, it is possible to improve the determination accuracy when determining on which branch of the branched road the vehicle is located, so that the current position of the vehicle can be calculated correctly, and the accurate current position of the vehicle is determined. It can be presented to the crew.

  In particular, when the car navigation device 1 displays guidance according to the type of road on which the vehicle is traveling, when traveling in the vicinity of the entrance / exit of the highway, the vehicle is traveling on the highway. Incorrect display such as highway information not being displayed or highway information being displayed even though the vehicle is traveling on a general road can be prevented.

(2) In determining which road the vehicle is traveling on after branching, the determination elements such as the heading difference Δθ and the perpendicular distance L are not considered. As a result, for example, even if the link direction is significantly different from the extended direction of the road, the current position of the vehicle is erroneously calculated due to the influence of the link direction that is significantly different from the extended direction of the road. Therefore, the current position of the vehicle can be calculated correctly, and the accurate current position of the vehicle can be presented to the occupant. Further, since unnecessary calculations can be omitted, the calculation load on the CPU 101 can be reduced, the calculation time required for calculating the current position can be shortened, and the response of displaying the current position can be improved.

(3) Considering only the road height information and the vehicle height displacement if it is possible to determine which road the vehicle is traveling on the basis of the road height information and the vehicle height displacement. Thus, before the reliability is calculated, it is configured to determine which road the vehicle is traveling on after branching. As a result, the error cost value ec and the accumulated error cost es do not have to be calculated based on the azimuth difference Δθ and the perpendicular distance L for the display candidate points on the link for which it is determined that the vehicle is not traveling. . Therefore, since unnecessary calculations can be omitted, the calculation load on the CPU 101 can be reduced, the calculation time required for calculating the current position can be shortened, and the response of displaying the current position can be improved.

(4) Based on the road height information and the vehicle height displacement, if it is possible to determine which road the vehicle is traveling on after branching, the road of the road that has not been determined to be traveling is determined. The display candidate points existing on the link are set to the maximum value (or a predetermined value determined in advance) that can take the value of the accumulated error cost es. As described above, the error cost value ec and the accumulated error cost es are calculated as described above for the display candidate points existing on the link of the road determined to be traveling. This prevents the display candidate point existing on the link of the road that has not been determined to be traveling from being erroneously calculated as the current position of the vehicle, while other than the branch link and the branch branch link. By comparing the reliability trst with display candidate points on other links, the most likely display candidate point as the current position can be calculated. Therefore, even when there are a plurality of display candidate points at the time of the previous calculation, the current position of the vehicle can be correctly calculated, and the accurate current position of the vehicle can be presented to the occupant.

---- Modified example ---
(1) In the above description, the maximum value that can take the value of the accumulated error cost es (or a predetermined value determined in advance) for display candidate points that exist on the link of the road that has not been determined to be traveling. However, the present invention is not limited to this. For example, the error cost value ec may be set to a maximum value (or a predetermined value) that can be taken. In this case, since the accumulated error cost es _n−1 calculated in the previous process is reflected in the accumulated error cost es calculated this time, the weighting coefficient k in the above-described equation (2) is temporarily increased. The degree of reflection of the accumulated error cost es _n−1 calculated in the previous process may be lowered. In addition, the value of the reliability trst of the display candidate point existing on the link of the road that is not determined to be traveling may be set to 0, for example, and the link of the road that is not determined to be traveling The display candidate points existing above may be deleted.

(2) In the above description, the general road and the highway extending to different height positions and the ramp connecting these are described, but the present invention is not limited to this. For example, the present invention can be applied even when there are two or more ordinary roads extending to different height positions and roads connecting them, and two or more highways extending to different height positions, The present invention can be applied even when there is a road (junction) connecting these.

(3) In the above description, the road height information is used as branching road judgment information for judging whether the road is located on a branch road that is information other than information related to the extension direction of the road. However, the present invention is not limited to this. For example, when the vehicle is configured to satisfy both of the following conditions (α) and (β), the vehicle can be detected only by the presence / absence of information indicating that the vehicle has passed the ETC gate (ECT gate). You may make it judge whether it is drive | working the branch road of the side where the gate is installed, or the branch road of the one where the ETC gate is not installed. That is, information regarding the installation position of the ETC gate may be used as branch path determination information.
(Α) An ETC in-vehicle device is connected to the car navigation device 1, and the car navigation device 1 is configured to be able to receive information indicating that the vehicle has passed through the ETC gate from the ETC in-vehicle device.
(Β) Information regarding the installation position of the ETC gate is stored in the road map data.

  In this case, whether the CPU 101 is traveling on the branch road where the ETC gate is installed or the branch road where the ETC gate is not installed is as follows. Judging. For example, it is assumed that one road is branched into two roads from the middle, and an ETC gate is installed at a node between the branch link b2 and the branch link b3 shown in FIG.

  When it is determined that the vehicle is traveling on the road as shown in FIG. 8, the CPU 101 determines that one of the display candidate points has moved from the link b2 to the link b3, but the vehicle is moved from the ETC onboard device to the ETC gate. If the information indicating that the vehicle has passed has not been acquired, the vehicle is present on the bifurcated branch link (that is, one of the links a1, a2, a3...) For the links b2, b3. Judge. And it sets to the maximum value (or predetermined value defined beforehand) which can take the value of accumulation error cost es about the display candidate point on link b3. For display candidate points on the branch branch link, the error cost value ec and the accumulated error cost es are calculated as described above. By calculating in this way, the same effects as those of the above-described embodiment can be obtained.

  As shown in FIG. 9A, when both the ETC gate installation information and the road height information exist, the road height information is displayed in front of the ETC gate installation position. If it exists, it will be judged which road after the branch is driven based on the road height information and the vehicle height displacement in preference to the judgment based on the ETC gate installation information. do it. In this case, if road height information exists in at least one of the branch links a1, a2 and the branch links b1, b2, the road height is prioritized over the determination based on the ETC gate installation information. Based on the height information and the vehicle height displacement, it is possible to determine which road after the branch is traveling.

  Further, as shown in FIG. 9B, when there is no road height information on the front side of the ETC gate installation position, the road height information on the other side of the ETC gate installation position. Even if it exists, it is only necessary to determine which road after the branch is traveling based on the ETC gate installation information. In addition, information regarding the installation location is stored in road map data such as radio wave beacons that transmit VICS information installed on the road and roadside wireless devices (described later) of roadside systems, and vehicles pass through these installation locations. If it can be detected, information regarding the installation position of the radio beacon or the roadside apparatus may be used as the branching road determination information.

  Here, the roadside system refers to the “Road” mentioned in the “Joint Research Report on the Next-generation Road Service Provision System (version 1.0)”, which is a joint research result between the National Institute for Land and Infrastructure Policy and the private sector. In the “information providing service” above, this is a system for providing safe driving support information, road traffic information, and the like to the vehicle side. The “information providing service on the road” is a system that transmits various kinds of information to the in-vehicle receiver using the DSC technology. A roadside apparatus is a transmitter for transmitting information by road-to-vehicle communication in a roadside system.

  Thus, when there are a plurality of types of branching road determination information, the road on which the vehicle has branched based on the branching road determination information that is determined to have the highest credibility among the plurality of branching road determination information It is only necessary to determine which one is located. If the road on which the vehicle travels can be identified based on the branch path determination information that is determined to have the highest credibility, other branch path determination information may not be used. Thereby, the determination accuracy at the time of determining on which branch road of the branched road the vehicle is located can be further improved.

(4) In the above description, only when the road is branched (Yes in step S133 in FIG. 6), the road height information is read (step S151 in FIG. 6). The present invention is not limited to this. Whether or not road height information is added to the link to which the display candidate point belongs may be confirmed in advance regardless of whether or not the road is branched.

(5) In the above description, the car navigation device for in-vehicle use has been described. However, the current position calculation device according to the present invention is not limited to in-vehicle use, but a navigation device mounted on a motorcycle or bicycle, or a navigation device for pedestrians. It can also be applied.
(6) The above-described embodiments and modifications may be combined.

  In the above embodiment and its modifications, for example, the presence / absence determination means, the position determination means, and the current position estimation means are realized by the CPU 101 and a program executed by the CPU 101. The above description is merely an example, and when interpreting the invention, there is no limitation or restriction on the correspondence between the items described in the above embodiment and the items described in the claims.

1 is a diagram illustrating an overall configuration of a car navigation device 1. FIG. It is the figure which showed the structure of the data for map display (road data). It is the flowchart which showed the operation | movement of the present position calculation process. It is a figure explaining a branch link. It is a figure which shows the example in case the general road and the highway are extended in a different height position. It is a flowchart which shows the subroutine of step S13 in the flowchart of FIG. It is a figure explaining the displacement of the height position of a display candidate point, and the displacement of the height direction of a vehicle. It is a figure which shows a modification. It is a figure which shows a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car navigation apparatus 11 Present location detection apparatus 100 Control apparatus 101 CPU
109 Map storage device

Claims (4)

Information (branch path judgment information) for judging where the road is branched, which is information other than information about the road's extension direction when the road is branched in the forward direction Presence / absence judging means for judging presence / absence before reaching a branch point of a road
When determining whether the branch road is located when the branch determination information is determined by the presence / absence determination means when determining which of the branched roads, the branch is made only by a determination based on the branch road determination information. It is determined on which of the roads, and if it is determined by the presence / absence determining means that the branching road determination information does not exist, the branching road is located on the road without using the branching road determination information. Position determination means for determining whether or not
A current position calculation device comprising: current position estimation means for estimating a current position based on a determination result of the position determination means. In the present position calculation device according to claim 1,
The position determination means is determined to have the highest credibility among the plurality of branch road determination information when there are a plurality of different branch road determination information for the branched road. When it is determined which of the branched roads is located based on the branch road determination information, and the road to be driven is identified based on the branch road determination information determined to be the most reliable The present position calculation device is characterized in that it does not use other branching path determination information. In the present position calculation device according to claim 1 or 2,
The branch position determination information includes information related to a road height. In the present position calculation device according to claim 3,
The position determining means acquires information on a change in the height position of the vehicle with traveling and compares the information with information on the height of the road to determine which of the branched roads the vehicle is located on. A current position calculation device characterized by that.

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