JPH08292050A - Current position calculating system and method therefor - Google Patents

Abstract

PURPOSE: To accurately judge a fact that a car travels on a road to be connected to a general road by performing an expressway outlet judging process and a reliability adding process in the case where such a proposed point as being the largest in reliability value exists on an expressway and has passed through a junction point. CONSTITUTION: A car's traveling direction and distance is found out of an azimuthal sensor 12, an angular velocity sensor 11 and a car speed sensor 13, calculating a virtual current position, and a proposed point is sought, and then stored in a memory 25. When a display proposed point exists on a line segment corresponding to an expressway, an expressway outlet judging process is executed at a time when it is so estimated that a car has passed through a junction point. In case of being highest in authenticity of a fact that the car is heading for an outlet of the expressway, a specified value is set to an expressway main track preferential distance counter, and consequently a reliability adding process is executed. Supposing that a line segment corresponding to a general road will not exist within the specified range, a specified bias value is added to the reliability of the proposed point on the line segment corresponding to an expressway main track, whereby the reliability adding process is carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mounted on a moving body such as a vehicle and measures the traveling distance and traveling direction of the moving body.
Accordingly, the present invention relates to a current position calculation system for calculating the current position of the moving body, and more specifically, a current position calculation for calculating the current position of the moving body when the moving body exists on an expressway. It is about the system.

[0002]

2. Description of the Related Art Conventionally, in a current position calculation system for calculating the current position of a vehicle traveling on a road, the current position of the vehicle is the traveling direction of the vehicle measured by a direction sensor such as a gyro and a vehicle speed sensor or distance. It is calculated based on the traveling distance of the vehicle measured by the sensor.

The traveling distance of the vehicle is generally measured by measuring the output shaft of the transmission or the rotation speed of the tire, and the distance is a distance that the vehicle travels per rotation of the tire. It is calculated by multiplying by.

Further, in order to correct the error of the current position obtained from the traveling direction and traveling distance of the vehicle as described above, as described in JP-A-63-148115, based on the traveling distance and the direction change amount. The estimated position of the vehicle determined and the amount of error based on the error of the road map are obtained, and the estimated position is registered as the self-position corresponding to all the roads located within the range of the amount of error centered on the estimated position. However, a technique is disclosed in which the correlation coefficient of each of the registered estimated positions for each road is calculated and the estimated position corresponding to the correlation coefficient indicating that the error for the road is the smallest is the current position.
In addition, in Japanese Examined Patent Publication No. 1-46004, the difference between the azimuth formed by the straight line connecting the folding points in the map information which approximates the road on the map and the azimuth detected by the azimuth detector is within a certain angle. For example, a technique for determining that a vehicle is moving forward on a road between breakpoints is disclosed. As described in these publications,
There is known a so-called map matching technique that corrects the obtained current position of the vehicle so as to match the road, and the accuracy of the current position calculation can be improved by this map matching technique.

[0005]

By the way, regarding the shape of the junction (branch point) of the highway, the main line of the highway extends straight and the road connecting to the general road is formed in a loop. In many cases. However, on the other hand, there are many cases where the roads connecting to general roads are formed almost parallel to the main road, especially regarding the shape of the junctions of highways in urban areas such as the Shuto Expressway and the Hanshin Expressway. To do.

[0006] When a vehicle travels near a branch point of a highway where the road connecting to the general road is formed substantially parallel to the main line as described above, the direction of the main line is connected to the general road. Since the difference with the direction of the road is small, considering the error of the direction sensor, even if the current position calculation device executes map matching, it is possible to accurately determine which road is traveling. There was a problem that it could not be done.

In particular, the vehicle calculated by the device when the device determines that the current position of the vehicle is on the road connecting to the general road even though the vehicle is traveling on the highway. There is a problem that the current position of the vehicle exists on the general road, and as a result, it becomes difficult to pull back the current position of the vehicle to the highway.

According to the present invention, when a vehicle is traveling on a junction in a highway, it is accurately determined that the vehicle is traveling on a road connecting to the main line of the highway or a general road. It is an object of the present invention to provide a current position calculation system that accurately calculates the current position of the vehicle.

[0009]

An object of the present invention is a current position calculation system mounted on a vehicle and calculating the current position of the vehicle, the road data including at least data indicating whether the road is a general road or an expressway. Means for storing map data representing a road map, a direction detecting means for detecting a traveling direction of the vehicle, a distance calculating means for calculating a traveling distance of the vehicle, and the traveling direction detected by the direction detecting means. And a virtual current position calculation unit that calculates a virtual current position that is expected to be the current position of the vehicle based on the travel distance calculated by the distance calculation unit, the virtual current position, and the map data. A candidate point calculation means for comparing the included road data with each other to calculate a candidate point indicating that the vehicle exists on any road, and a position where the candidate point exists for the vehicle. Reliability calculating means for calculating the reliability indicating the credibility, one of the candidate points having the highest reliability value is present on the highway, and the highest reliability value. And a connecting road judging means for judging whether or not the road having the candidate point having the largest reliability value is connected to the general road when the candidate point having a large value passes through a branch point in the highway. , When the road is connected to an ordinary road, on the main line of the highway during a period in which the vehicle travels a predetermined distance after the candidate point having the highest reliability value passes through the branch point. A bias value adding means for adding a predetermined bias value to the reliability of the candidate points existing in, a candidate point to which a predetermined bias value is added by the bias value adding means, and other candidate points are compared, Position of the candidate point with the highest confidence value It is accomplished by the current position calculating system comprising a current position determining means for the current position of the vehicle.

[0010] In a preferred aspect of the present invention, the connecting road judging means connects a road having a candidate point with the highest reliability value within a predetermined range from the branch point to a general road. Is configured to determine whether or not

[0011] In a further preferred aspect of the present invention, the virtual current position calculating means determines, from a candidate point, the traveling azimuth detected by the azimuth detecting means and the traveling distance calculated by the distance calculating means. The candidate point, which is configured to calculate a position to which a relative displacement based on is added, is calculated as a virtual current position, and which is the basis for the connecting road determination means to calculate the candidate point having the largest reliability value. Is configured to determine whether a plurality of candidate points have been calculated.

[0012] In a further preferred aspect of the present invention, the candidate point calculating means is present within a predetermined range from the virtual current position calculated by the virtual current position calculating means, and a difference between the azimuth and the traveling azimuth. Is configured to set the candidate point on a road smaller than a predetermined value.

[0013]

According to the present invention, of the candidate points, one candidate point having the highest reliability value exists on the expressway, and
When the candidate point with the highest reliability value passes through a branch point on the highway, the connecting road determination means determines whether the road with the candidate point with the highest reliability value is connected to a general road. When the road extending from the branch point is connected to the general road, the bias value adding means determines whether or not the candidate point with the highest reliability value passes through the branch point and then on the main line of the highway. A predetermined bias value is added to the reliability of the candidate points existing in, and the current position determination means compares the candidate point to which the predetermined bias value is added with other candidate points, and the value of the highest reliability is Since the position of the large candidate point is the current position of the vehicle, it is determined that the current position of the vehicle is on the road connecting to the general road even though the vehicle is traveling on the main line of the highway. Can be prevented.

Further, the bias adding means is configured to add a predetermined bias value to the reliability of the candidate points existing on the expressway during the period when the vehicle travels a predetermined distance. When traveling on a road connected to a general road, it is possible to prevent the current position of the vehicle from being determined to be on the main line of the expressway.

That is, according to the present invention, when the vehicle is traveling on a junction in a highway, the vehicle is traveling on a main line of the highway or on a road connected to a general road, It is possible to make an accurate judgment.

According to a further preferred aspect of the present invention, the candidate point calculating means exists on a road existing in a predetermined range from the virtual current position, and the difference between the azimuth and the traveling azimuth is smaller than a predetermined value. Since the candidate points are set, the current position of the vehicle can be calculated accurately.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of the present position calculating apparatus according to the embodiment of the present invention. As shown in FIG. 1, the present position calculation device 10 includes an angular velocity sensor 11 that detects a yaw rate of a vehicle to detect a change in traveling direction, and a geomagnetic sensor 12 that detects a traveling direction of a vehicle by detecting geomagnetism. And a vehicle speed sensor 13 that outputs pulses at intervals proportional to the rotation of the output shaft of the vehicle transmission.

Also, a display 17 for displaying a map around the current position, a mark indicating the current position, etc., a switch 14 for accepting from the (driver) a command for switching the scale of the map displayed on the display 17, and a digital map. CD-ROM 15 for storing data and its CD
A driver 16 for reading map data from the ROM 15. Further, the controller 18 for controlling the operation of each peripheral device described above is provided. In the present embodiment, the digital map data described above includes road data composed of coordinates indicating the ends of a plurality of line segments,
Alternatively, it includes road width data indicating the road width of the road, a highway flag indicating whether the road is a highway or a general road, and the like.

The controller 18 includes an A / D converter 19 for converting the signal (analog) of the angular velocity sensor 11 into a digital signal, and an A / D converter 20 for converting the signal (analog) of the geomagnetic sensor 12 into a digital signal. , Vehicle speed sensor 1
A counter 26 that counts the number of pulses output from the CPU 3 every 0.1 seconds, a parallel I / O 21 that inputs whether or not the switch 14 is pressed, and a DMA (that transfers the map data read from the CD-ROM 15 ( Direct Memory Acce
ss) It has a controller 22 and a display processor 23 for displaying a map image on the display 17.

The controller 18 also has a microprocessor 24 and a memory 25. The microprocessor 24 outputs the signal of the angular velocity sensor 11 obtained through the A / D converter 19, the signal of the geomagnetic sensor 12 obtained through the A / D converter 20, and the output pulse of the vehicle speed sensor 13 counted by the counter 26. Number, whether or not the switch 14 is pressed through the parallel I / O 21, and the map data from the CD-ROM 15 obtained through the DMA controller 22 are received and processed based on those signals, The current position is calculated and displayed on the display 17 via the display processor 23. The display of the vehicle position is performed by superimposing an arrow mark or the like on the map which is already displayed on the display 17, as shown in FIG. This allows the user to know the current position of the vehicle on the map. The memory 25 is
It includes a ROM that stores a program that defines the contents of processing (described later) for realizing such operations, and a RAM that is used as a work area when the microprocessor 24 performs the processing.

The operation of the present position calculation device 10 thus configured will be described below.

The operation of the apparatus 10 is generally performed by a process of calculating the traveling direction and traveling distance of the vehicle, a process of determining the current position of the vehicle from the calculated traveling direction and distance, and the obtained vehicle position and Since it can be divided into three processes, that is, the process of displaying the azimuth, these processes will be described sequentially.

FIG. 3 illustrates the flow of processing for calculating the traveling direction and traveling distance of the vehicle.

This processing is carried out at a constant cycle, for example 100 m.
This is a routine of the microprocessor 24 that is activated and executed for each S.

In this routine, first, the A / D converter 1
The output value of the angular velocity sensor 11 is read from 9 (step 401). Since the azimuth change is output as the output value of the angular velocity sensor 11, only a relative value in the traveling direction of the vehicle can be detected. Therefore, next, the output value of the geomagnetic sensor 12 is read from the A / D converter 20 (step 40
2) The estimated azimuth of the vehicle is determined using the absolute azimuth calculated from the output value of the geomagnetic sensor 12 and the azimuth change (angular velocity output) output from the gyro 11 (step 403).

This azimuth determination can be performed, for example, for a long time,
When the vehicle speed is low, the error of the angular velocity sensor is large, so
When the vehicle speed is low for a certain period of time or more, the method is performed by using only the geomagnetic sensor direction.

Next, the number of pulses output from the vehicle speed sensor 13 is counted by the counter 26 every 0.1 seconds, and the counted value is read (step 404). By multiplying the read value by the distance coefficient, the distance advanced in 0.1 second is obtained (step 405).

Next, the traveling distance value per 0.1 second thus obtained is integrated with the previously obtained value,
It is checked whether the traveling distance of the vehicle has reached 20 m (step 406), and if it is less than 20 m (step 406).
No), the process of this time is ended and a new process is started.

As a result of the traveling distance calculation processing, when the accumulated traveling distance becomes a constant distance, for example, 20 m (Yes in step 406), the traveling direction and traveling distance (20 m) at that time are output (step). 407). In step 407, the cumulative distance is further initialized, and the cumulative traveling distance is newly started.

Next, the process of calculating the virtual current position of the vehicle based on the calculated traveling azimuth and traveling distance and obtaining the candidate points of the vehicle based on the calculated virtual current position will be described.

FIG. 4 shows the flow of this processing.

This processing is a routine of the microprocessor 24 which is started and executed in response to the output of the traveling direction and traveling distance from FIG. That is, this process is started every time the vehicle advances 20 m.

In this process, first, step 40
The traveling direction and traveling distance output in 7 are read (step 501). Next, based on those values, the amount of movement of the vehicle is obtained separately in the latitude and longitude directions. Further, the movement amount in each of these directions is added to the position of the vehicle candidate point obtained in the previous processing to obtain the virtual current position (A) which is the position where the current vehicle is estimated to exist (step 502). Details of this candidate point will be described later.

If the position of the previously obtained candidate point does not exist, such as immediately after the start of the apparatus, the position set separately is used as the position of the previously obtained candidate point and the virtual current position (A) is used. Ask for.

Next, a map around the obtained virtual current position (A) is obtained from the CD-ROM 15 by the drivers 16 and D.
The road data (line segment) read out through the MA controller 23 and within a preset distance D centered on the virtual current position (A) is selected and taken out (step 503).

As described above, in this embodiment, road data is approximated by a plurality of line segments 51 to 55 connecting two points as shown in FIG. 5, and these line segments are
The one represented by the coordinates of the start point and the end point is used. For example, the line segment 53 has its starting point (x3, y3)
And the end point (x4, y4).

Next, from the line segments extracted in step 503, only the line segment whose azimuth is within the predetermined traveling direction and the required traveling direction is selected (step 5
04). Further, a vertical line is drawn from the virtual current position (A) for all the extracted n line segments, and the vertical line L
The length of (n) is calculated (step 505).

Next, based on the lengths of these perpendiculars, the error cost value ec (n) defined by the following equation is calculated for all the line segments extracted in step 504.

Ec (n) = α × | θcar−θ (n) | +
β | L (n) | where θcar is the vehicle direction at the virtual current position (A), θ (n) is the direction of the line segment, and L (n) is the virtual current position (A) to the line segment. , The length of the perpendicular, α
And β are weighting factors. The values of these weighting factors are
The deviation between the traveling direction and the direction of the road, or the deviation between the current position and the road may be changed depending on whether the current position is prioritized in selecting the road on the road. For example, when a road whose direction is close to the traveling direction is important, α is increased.

Here, the candidate points will be described. In an initial state such as immediately after the start of the device, the virtual current position (A) is uniquely determined by the user (driver) inputting predetermined information using the switch 14,
And this position exists on the line segment corresponding to the road. However, after the vehicle has traveled, the virtual current position (A) may not exist on the line segment corresponding to the road due to an error of a direction sensor such as a gyro. As a result, for example, as shown in FIG. 6, when the road is branched, that is, when two line segments 64 and 65 appear from the node 68 of the line segment 61 corresponding to the road, which line segment is present? It is often impossible to clarify whether there is a vehicle on the road corresponding to.

Therefore, in such a case, in this embodiment, predetermined points existing on two conceivable line segments are set as candidate points, and their current position, error cost, and accumulation described later. Error cost, etc.
The memory 25 is configured to be stored in a predetermined area of the RAM. In addition, in order to facilitate the description, in the following description, one or more new candidate points will be generated from a single candidate point, unless it is clearly indicated that there are a plurality of candidate points.

Then, the calculated error cost ec
According to (n) and the accumulated error cost es related to the candidate points calculated in the previous process, the accumulated error cost es (n) in this process defined by the following formula is calculated ( Step 506).

Es (n) = (1−k) × es + k × ec (n) Here, k is a weighting coefficient larger than 0 and smaller than 1. This accumulated error cost es (n) represents how much the error cost calculated in the previous process is reflected in the error cost calculated in this process.

Further, the calculated cumulative error cost es
The reliability trst defined by the following equation based on (n)
(N) is calculated (step 506).

Trst (n) = 100 / (1 + es (n)) As apparent from the above equation, the accumulated error cost ec
The reliability trst increases as (n) increases.
(N) decreases and approaches 0 (zero). On the other hand, as it becomes smaller, the reliability trst (n) increases, and its value approaches 100.

By performing such processing, n existing in the predetermined range D from the current position A for a certain candidate point
The reliability trst (n) associated with each line segment is obtained. When there are a plurality of candidate points, the reliability trst (m, n) related to n line segments existing in the predetermined range D from each candidate point Cm may be calculated.

Then, based on the calculated reliability trst (n), the point advanced from a certain candidate point along the corresponding line segment by the length corresponding to the distance R traveled by the vehicle is
A new candidate point C (n) is set (step 507). Therefore, when the number of line segments existing in a predetermined range D from the current position A for a certain candidate point and the difference between the azimuth and the vehicle azimuth is a predetermined value or less is n, n A new candidate point C (n) will be generated.

Further, the new candidate points C (n) are sorted according to the value of the reliability trst (n) corresponding to each of the new candidate points C (n) (step 508),
The position, accumulated error cost, reliability, etc. of the candidate point C (i) having the largest reliability value as a display candidate point CD, that is, the candidate point for displaying on the display 17, is stored in the memory 25. The positions of candidate points other than the display candidate points, the accumulated error cost, the reliability, etc. are stored in a predetermined area of the RAM while being stored in a predetermined area of the RAM (step 509).

For example, as shown in FIG. 6, it is assumed that the current position A is represented by the position indicated by the point 63 with respect to a certain candidate point 62 existing on the line segment 61. In such a case, the line segments 64 and 6 which are present in the predetermined range D from the current position A and in which the difference between the direction and the vehicle direction is less than or equal to the predetermined value.
5, the distances L (1) and L (2) from the current position A to the line segments 64 and 65 are calculated, and the calculated distances and the angles θ (1) and θ (of the line segments 64 and 65 are calculated. 2) and the related error cost based on the vehicle direction θcar, etc.
Calculate the accumulated error cost and reliability. Further, based on the traveling distance R of the vehicle obtained in step 405 of FIG. 3, a length corresponding to the traveling distance R from a certain candidate point 62 along the line segments 61 and 64 or the line segments 61 and 65. The position advanced by only is calculated, and the points corresponding to this position are set as candidate points 66 and 67, respectively. Of the candidate points 66 and 67 thus obtained, the highest reliability trs
A display candidate point has a large value of t.

Further, as shown in FIG. 7, with respect to the candidate point 66 on the line segment 64, the new current position A is represented at the position indicated by the point 71, while the candidate on the line segment 65 is selected. Point 67
On the other hand, it is assumed that the new current position A ′ is represented by the position indicated by the point 72. In this case, the line segments 73 and 74 existing in the predetermined range D from the current position A and having a difference between the azimuth and the vehicle direction of a predetermined value or less are taken out, and the new range A ′ from the new current position A ′ is extracted. A line segment 75 existing in D and having a difference between the heading and the vehicle heading equal to or less than a predetermined value is extracted. Then, the distances L1 (1) and L1 (2) from the current position A to the line segments 73 and 74 are calculated, and the distance L2 from the current position A ′ to the line segment 73 is calculated.
Calculate (1). Furthermore, the distance calculated in relation to the current position A, the angles θ1 (1) and θ of the line segments 73 and 74
1 (2) and the vehicle heading θcar, the related error cost, accumulated error cost and reliability are calculated, and the distance calculated in relation to the current position A ′ and the angle θ2 (1 of the line segment 73 are calculated. ) And the vehicle direction θcar, etc., and the associated error cost, accumulated error cost, and reliability are calculated.

Further, based on the traveling distance R of the vehicle obtained in step 405 of FIG.
4 and 73, or along line segments 64 and 74,
Alternatively, a position advanced from the candidate point 67 along the line segments 65 and 75 by a length corresponding to the mileage R of the vehicle is calculated, and the points corresponding to this position are respectively set as new candidate points. . FIG. 8 shows the candidate points 81 to 83 newly obtained in this way. Note that among the candidate points 81 to 83, as in the example described with reference to FIG.
The candidate having the highest reliability trst is the display candidate point. In addition, in the present embodiment, the data related to the 14 candidate points can be stored. Therefore, when 15 or more candidate points are calculated as a result of performing the processing of steps 501 to 509 of FIG. 4, among these, various values related to 14 candidate points in descending order of the reliability trst value are displayed. Will be stored in a predetermined area of the RAM of the memory 25.

By the way, in the above-mentioned step 503,
A preset distance D centered on the virtual current position (A)
Although the road data (line segment) inside is taken out, this distance D may be a value determined based on the value of the reliability trst of the candidate point calculated in step 509 performed last time.

The reason for obtaining the search range based on the reliability is that the reliability of the accuracy of the current position obtained last time is considered to be low when the reliability is low, and therefore a wider range is searched. This is because searching for a road is more suitable for obtaining the correct current position.

Further, it is possible that there is no line segment within the predetermined range D from the current position A for a certain candidate point such that the difference between the direction and the traveling direction of the vehicle is a predetermined value or less. In this case, the current position A is the next candidate point calculated from a certain candidate point. In this embodiment, such a state of the candidate points is called a free state. On the other hand, in other states, that is, within the predetermined range D from the current position A for a certain candidate point, there is a line segment whose difference between the direction and the traveling direction of the vehicle is a predetermined value or less. As a result, a state in which the next candidate point may exist on a specific line segment is called a matching state.

If there is no line segment within the predetermined range D from the current position A in which the difference between the direction and the traveling direction of the vehicle is less than the predetermined value, the error cost ec to be calculated in step 506. (N) is given a constant value that is larger than the value of the error cost obtained in the matching state.

After the processing up to step 509 is executed, the candidate points including the display candidate points are generated, and various data related thereto are stored in a predetermined area of the RAM of the memory 25, and then the expressway main line priority is given. The process is executed (step 510). FIG. 9 is a flowchart showing the expressway main line priority processing executed in step 510.

In the expressway main line priority process, first, it is determined whether or not the display candidate point exists on the line segment corresponding to the expressway (step 901). No in this step (N
If it is determined to be o), the process proceeds to step 904. On the other hand, in this step 901, Yes (Ye
If it is judged as s), it is judged whether or not the display candidate point is a point immediately after passing the branch point (step 9).
02). More specifically, this step 902 determines whether or not a plurality of candidate points including the display candidate points are calculated from the candidate points obtained in the previous process, which are the basis for calculating the display candidate points. It is executed by judging.

When it is judged YES in this step 902, the expressway exit judgment processing is executed (step 903). This highway exit determination process is
To determine whether the road corresponding to the line segment on which the display candidate point is present among the roads connected to the branch point is a general road, that is, that this road leads to the exit of the expressway belongs to.

FIG. 10 is a flow chart showing the highway exit determination processing. As shown in FIG. 10, in this process, first, a line segment corresponding to a road on which the display candidate point exists is searched (step 1001), and whether this line segment corresponds to a general road or not. It is determined whether or not (step 1002). In step 1002, no (N
If it is determined to be o), it is determined whether or not the search is 400 m or more, that is, the position of this line segment is 400 m from the branch point.
It is determined whether or not the above is true (step 1003), and if it is determined to be Yes, this road does not lead to the exit of the highway, that is, the road is the main line of the highway, The highway exit flag flag is set to 0, and the highway exit determination process ends. On the other hand, if it is determined No in step 1003, the process returns to step 1001 and the same processing is repeated for the line segment connected to the previously searched line segment.

In step 1002, YES
s) is determined, a predetermined value is set in the expressway main line priority distance counter L for defining a period for executing the reliability addition processing described later, for example, 500 m in this embodiment.
Set the value corresponding to (step 100
5) The highway exit determination flag flag = 1 for determining whether or not to execute the reliability addition processing described later is set (step 1006).

Expressway exit determination processing (step 903)
When is finished, in step 904, it is determined whether or not the highway exit determination flag flag = 1 (step 904). If it is determined No in step 904, the process proceeds to step 906.

On the other hand, in step 904, Yes (Ye
If it is determined to be s), reliability addition processing is executed (step 905). FIG. 11 is a flowchart showing the reliability addition processing. As shown in FIG. 11, in this process, first, a predetermined bias value hys is added to the reliability trst of the candidate points existing on the line segment corresponding to the main line of the expressway (step 1101).
Next, the value of the expressway priority distance counter L is decremented by the value corresponding to the traveling distance R of the vehicle obtained in step 405 of FIG. 3 (step 1102).

Furthermore, this expressway priority distance counter L
If the value of is less than or equal to 0, and if the result is no (No), the process is terminated as it is.
s), the highway exit determination flag flag
= 0, the value of the expressway priority distance counter L is reset to 0 (step 1104), and the process ends.

Thus, steps 901 to 905
After the processing of (1) is completed, the reliability trst of each candidate point is checked, and the candidate points are sorted again in descending order of the reliability value. Then, with the candidate point having the highest reliability as the display candidate point, the data related to the position and orientation are stored in the memory 2.
5 is stored in a predetermined area of the RAM, and data relating to other candidate points is also stored in a predetermined area of the RAM of the memory 25 (step 906).

Next, the significance of each process will be made clearer by explaining the order in which the steps of the processes shown in FIGS. 9 to 11 are executed.

When the display candidate point exists on the line segment corresponding to the highway, that is, when the vehicle is most confident that the vehicle is traveling on the highway, the vehicle has passed the branch point. When it is estimated, the highway exit determination processing is executed (steps 901 to 903). For example,
As shown in FIG. 12, the processing of steps 501 to 509 of FIG. 4 is executed in relation to the candidate point 120, and the candidate point C is calculated based on the virtual current position A (121 in the figure).
(1) 122 and candidate point C (2) 123 are generated,
If any of these candidate points is determined to be a display candidate point, the expressway exit determination process is executed.

As described above, in the highway exit determination processing (step 903 in FIG. 9), if the line segment where the display candidate point, which is the position of the vehicle with the highest credibility, exists is extended, it is within the predetermined distance range. It is determined whether or not there is a line segment corresponding to a general road. That is, it is determined whether or not the vehicle has the highest credibility toward the exit of the highway (steps 1001 to 10 in FIG. 10).
03). For example, in the example of FIG. 12, the candidate point C
When (1) is the display candidate point, the line segments 124, 12
If the line segment 127 corresponding to the general road exists within a predetermined range by following 5, 126, a predetermined value is set in the expressway main line priority distance counter L (step 10).
05), the expressway exit determination flag flag = 1 is set (step 1006). As a result, in this case, the reliability addition processing (step 905) is executed.
In this embodiment, the value of 500 m given to the expressway main line priority distance counter L corresponds to the distance at which a clear difference in shape appears between the expressway main line and other lines. ing. However, this value is not limited to this, and may be set in advance in accordance with the road conditions and the like.

On the other hand, in the example of FIG. 12, the candidate point C
When (2) is a display candidate point, line segments 128, 129,
If there is no line segment corresponding to the general road within the predetermined range even after tracing 130, it is determined that these line segments correspond to the main line of the highway, and the flag flag = 0.
Therefore, the reliability addition processing (step 905) is not executed.

In the reliability addition processing (step 905),
To the reliability of the candidate points on the line segment corresponding to the main line of the highway,
A predetermined bias value hys is added (step 110).
1). To explain again using the example of FIG. 12, when the display candidate point is the candidate point C (1), the reliability of the candidate point C (2) 123 on the line segment 128 corresponding to the main line of the expressway is calculated. The bias value is added every time. Thus, the candidate point C
Adding the predetermined bias value hys to the reliability of (2) is based on the result of steps 501 to 509 of FIG.
Candidate point C (1) was determined to be the most credible, but the vehicle deviates from the mainline of the highway only once, that is, when it leaves the highway. Considering that the number of times a vehicle passes through a branch point in an expressway along the expressway main line is very large, a candidate point C (2) on a line segment corresponding to the expressway main line is considered. Enhances the credibility of the current location.

This step 1101 is performed until the expressway priority distance counter L becomes 0 (zero) or less, that is,
The process is executed until the vehicle travels a predetermined distance, for example, 500 m in this embodiment, and the bias value is added to the reliability of the candidate points on the line segment corresponding to the expressway.

In this way, after the reliability addition distance (step 905 in FIG. 9) is executed, the value of the reliability trst of each candidate point is checked again in step 906.
The candidate point having the largest reliability trst value is set as the display candidate point. After the highway exit determination processing (step 903) is executed, the vehicle is at a predetermined distance, 500 m in this embodiment.
Since the bias value hys is added to the reliability of the candidate points existing on the line segment corresponding to the main line of the highway until the vehicle runs, the added bias value hys corresponds to the highway. Candidate points existing on the line segment corresponding to the main line are more likely to be displayed candidate points. Therefore, there is no big difference between the direction of the mainline of the highway and the direction of the lane heading for the exit, and as a result, the vehicle is traveling on the mainline of the highway due to an error in the direction sensor or the like. Regardless, the calculated current position of the vehicle is prevented from deviating from the main line of the highway.

After the above-mentioned processing is completed, the position and orientation of the display candidate point are output (step 511 in FIG. 4).

The display candidate points obtained by executing steps 501 to 511 of FIG. 4 are displayed on the screen of the display 17 by the processing based on the flowchart shown in FIG.

This process is a routine of the microprocessor 24 which is activated and executed every one second.

First, it is determined whether or not the switch 14 is instructed to change the map scale by looking at the contents of the parallel I / O 21 (step 1301). If it is pressed (Yes in step 1301), a predetermined scale flag is set correspondingly (step 130).
2).

Next, the data indicating the position and orientation of the display candidate points obtained by executing the processing of FIG. 5 is read from a predetermined area of the RAM of the memory 25 (step 1303) and switched in step 1302. The map of the scale according to the content of the scale flag is displayed on the display 17,
For example, it is displayed in the state as shown in FIG. 2 (step 1
304).

Then, the position and the direction of the display candidate point are displayed by superimposing them on the map, for example, by using the arrow symbol "↑" as shown in FIG. 2 (step 130).
5). Finally, the north mark indicating north and the distance mark corresponding to the reduced scale are displayed as shown in FIG. 2 so as to be superimposed on them (step 1306).

In the present embodiment, the vehicle position and the direction are indicated by using the arrow symbols as described above, but the display form of the vehicle position and the direction shows that the position and the traveling direction are
The form may be arbitrary as long as the display state is clearly shown. The same applies to the north mark and the like.

According to this embodiment, when the display candidate point exists on the line segment corresponding to the highway and the display candidate point has passed the branch point, the display candidate point exists. If the line segment that corresponds to the general road is connected, the line segment that corresponds to the main line of the highway is checked while the vehicle is traveling for a predetermined distance. A predetermined bias value is given to the reliability of the candidate points existing in.
Therefore, there is a high possibility that the candidate points existing on the line segment corresponding to the main line of the highway will be determined as the display candidate points according to the given bias value, and as a result, the main lines of the highway and the highway will be There is no significant difference between the direction of the vehicle and the direction of the lane heading for the exit, and due to an error in the direction sensor, etc., the calculated vehicle current It is possible to prevent the position from deviating from the main line of the highway.

On the other hand, the bias value is added to the reliability of the candidate points existing on the line segment corresponding to the main line of the expressway only while the vehicle travels a predetermined distance. When traveling on the lane heading for, the current position of the vehicle is the lane connected to the general road, that is,
It also becomes possible to prevent departure from the lane heading for the exit of the highway.

The present invention is not limited to the above embodiments, but various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. It goes without saying that it is one.

For example, in the above-described embodiment, step 902 in FIG. 9 includes a plurality of display candidate points, including the display candidate points, from the candidate points obtained in the previous processing, which are the basis for calculating the display candidate points. By determining whether the candidate point has been calculated, it is determined that the display candidate point has passed the branch point.However, from the display candidate point, the line segment is searched for the length corresponding to the predetermined distance. Alternatively, it may be determined whether or not a branch point exists within the range of the length.

Further, in the expressway main line priority processing of the above-described embodiment, the value set in the set expressway main line priority counter and the reliability of the candidate points existing on the line segment corresponding to the expressway main line are added. Obviously, the applied bias value is not limited to those described in the above embodiments.

Further, in the present specification, the term "means" does not necessarily mean physical means, but also includes the case where the function of each means is realized by software. Further, the function of one means may be realized by two or more physical means, or the functions of two or more means may be realized by one physical means.

[0086]

According to the present invention, when a vehicle is traveling on a junction on a highway, it is possible to accurately determine whether the vehicle is traveling on a highway or another road. It becomes possible to provide the system.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a current position calculation device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a display example of a map and a current position according to the present embodiment.

FIG. 3 is a flowchart showing a process of calculating a traveling direction and a traveling distance of a vehicle.

FIG. 4 is a flowchart showing a process of calculating the current position of the vehicle.

FIG. 5 is a diagram for explaining an example of road data according to the present embodiment.

FIG. 6 is a diagram for explaining a line segment corresponding to a road, a virtual current position, and a candidate point.

FIG. 7 is a diagram for explaining a line segment corresponding to a road, a virtual current position, and a candidate point.

FIG. 8 is a diagram for explaining a line segment corresponding to a road, a virtual current position, and a candidate point.

FIG. 9 is a flowchart showing a highway main line priority process according to the present embodiment.

FIG. 10 is a flowchart showing a highway exit determination process according to the present embodiment.

FIG. 11 is a flowchart showing a reliability adding process according to the present embodiment.

FIG. 12 is a diagram for explaining a highway main line priority process according to the present embodiment.

FIG. 13 is a flowchart showing a current position display process according to this embodiment.

[Explanation of Codes] 10 Current Position Calculator 11 Angular Velocity Sensor 12 Direction Sensor 13 Vehicle Speed Sensor 14 Switch 15 CD-ROM 16 CD-ROM Read Driver 17 Display 18 Controller

Claims (5)

[Claims] 1. A current position calculation system which is mounted on a vehicle and calculates the current position of the vehicle, wherein the map represents a road map including at least road data including data indicating whether the vehicle is an ordinary road or an expressway. A means for storing data, an azimuth detecting means for detecting a traveling azimuth of the vehicle, a distance calculating means for calculating a traveling distance of the vehicle, the traveling azimuth detected by the azimuth detecting means, and a distance calculating means A virtual current position calculating means for calculating a virtual current position expected to be the current position of the vehicle based on the traveled distance, and the virtual current position, and the road data included in the map data. A candidate point calculating means for calculating a candidate point indicating that the vehicle exists on any road, and a signal indicating the credibility that the candidate point is the position where the vehicle exists. A reliability calculation means for calculating a reliability, one of the candidate points having the highest reliability value exists on a highway, and the candidate point having the highest reliability value is high speed. When passing a fork in the road,
The road where the candidate point with the highest reliability value is,
Connected road determination means for determining whether or not connected to a general road, when the road is connected to a general road, after the candidate point with the highest reliability value has passed the branch point,
Bias value adding means for adding a predetermined bias value to the reliability of the candidate points existing on the main line of the highway during a period in which the vehicle travels a predetermined distance; and a predetermined bias value by the bias value adding means. The present invention is characterized in that the current position determining means compares the candidate point to which is added with other candidate points and determines the position of the candidate point having the largest reliability value as the current position of the vehicle. Position calculation system. 2. The connecting road judging means judges whether or not a road in which a candidate point having the highest reliability value exists within a predetermined range from the branch point is connected to a general road. The present position calculation system according to claim 1, wherein the present position calculation system is configured as described above. 3. The virtual current position calculating means, from the candidate points,
It is configured to calculate a position obtained by adding a relative displacement based on the traveling azimuth detected by the azimuth detecting unit and the traveling distance calculated by the distance calculating unit, as a virtual current position. The means is configured to judge whether or not a plurality of candidate points have been calculated from the candidate points, which is a basis for calculating the candidate point having the highest reliability value. The current position calculation system according to claim 2. 4. The candidate point calculating means exists within a predetermined range from the virtual current position calculated by the virtual current position calculating means, and a difference between the azimuth and the traveling azimuth is smaller than a predetermined value. The present position calculation system according to any one of claims 1 to 3, wherein the candidate point is set on a road. 5. A current position calculating method for calculating a current position of a vehicle according to a traveling direction of the vehicle and a traveling distance of the vehicle, wherein the current position of the vehicle is calculated based on the traveling direction of the vehicle and the traveling distance. A virtual current position expected to be present is calculated, and the virtual current position is compared with road data including at least data indicating whether it is an expressway or a general road, and the vehicle is present on any road. Calculating a candidate point that indicates that the candidate point is a reliability indicating the credibility that is the position where the vehicle is present, of the candidate points, one candidate with the highest reliability value If the point exists on the highway and the candidate point with the highest reliability value passes through the branch point in the highway,
The road where the candidate point with the highest reliability value is,
If the road extending from the branch point is connected to the general road, it is determined whether or not the candidate point having the highest reliability value passes through the branch point, and then the vehicle During a period of traveling for a predetermined distance, a predetermined bias value is added to the reliability of the candidate points existing on the main line of the highway, and the candidate point to which the predetermined bias value is added and other candidates. A current position calculating method, characterized in that the position of a candidate point having the highest reliability value is determined as the current position of the vehicle by comparing with the point.