JPH08334360A - Present location calculating device - Google Patents

Abstract

PURPOSE: To prevent a present location calculating device from making erroneous correction of a distance factor at a location at which the shape of a road is uncertain. CONSTITUTION: A microprocessor 214 generates a short-term correction variable to be used for correcting a distance factor for a short term based on the cumulative difference between the azimuths of a road and its own vehicle when the difference does not nearly continuously exceed a prescribed value. On the other hand, the microprocessor 214 generates a long-term correction variable to be used for correcting a distance factor for a long term based on the contribution of the correction of the distance factor to the traveling distance of the vehicle. The microprocessor 214 sets the contribution to '0' when the microprocessor 214 has a chance to calculate the contribution of the distance factor correction to the traveling distance while the vehicle travels a prefixed distance after the microprocessor 214 detects that the vehicle enters an expressing from an ordinary road.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current position calculating device which is mounted on a moving body such as a vehicle, measures the distance traveled, the heading and the like and calculates the current position of the vehicle from these. In particular, the present invention relates to a technique for correcting the measurement error of the traveling distance.

[0002]

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

Further, the mileage of a vehicle is generally a distance coefficient which is a distance traveled by the vehicle per one rotation of the tire by measuring the rotational speed of the output shaft of the transmission or the tire. It is calculated by multiplying by.

Further, in order to correct the error of the current position obtained from the traveling direction of the vehicle and the traveling distance in this way, as in the technique described in Japanese Examined Patent Publication No. 6-13972, it is calculated so as to match the road data. The current position of the vehicle
A so-called map matching technique is known. According to this map matching technique, the accuracy of position calculation can be improved.

By the way, during running, tire wear and
The diameter of the tire, that is, the distance coefficient, changes with time due to expansion and the like due to temperature changes. Therefore, an error occurs in the calculation of the traveling distance, and the current position cannot be calculated with high accuracy. For example, if there is an error of 1% in the traveling distance coefficient per one rotation of the tire, an error of 1 km will occur when the vehicle travels 100 km.

[0006] Such a traveling distance measurement error can be corrected to some extent by the above-described map matching technique when traveling on an ordinary road. However, when there is an opportunity to travel on a road such as an expressway, it is not possible to sufficiently correct the error because the road does not have features such as curves and intersections that can be used in map matching.

Furthermore, once an error of about 1 km occurs between the measured current position and the true current position,
Depending on the map matching technique, it may be difficult to correct the position.

Therefore, in order to eliminate an error in the measurement of the traveling distance, conventionally, (1) road data from when the vehicle turns an intersection (start point) to when it turns the next intersection (end point),
The distance coefficient per one rotation of the tire has been corrected by comparing the running distance obtained from the measured rotation speed. Further, as described in (2) Japanese Patent Publication No. 6-27652, a technique for correcting the distance coefficient described above by comparing the distance on the map between two beacons and the distance measured by traveling. Is also known. Also,
(3) As described in Japanese Patent Application Laid-Open No. 2-107959, G
GPS that calculates the current position using signals from PS satellites
A technique is also known in which a vehicle speed is obtained using a receiving device and the detected vehicle speed is compared with the detected vehicle speed to correct the distance coefficient.

[0009]

However, in the above-mentioned technique (1), if the road between the intersections is slightly curved or the vehicle is meandering, accurate correction cannot be performed. There is also a problem that it is difficult to accurately specify the start and end points described above. For example, when there are a plurality of lanes at an intersection, the starting and ending points differ depending on which lane the vehicle is going through, but it is not easy to identify such a lane.

Further, the above-mentioned technique (2) also has a problem in that accurate correction cannot be performed unless the road is straight, and that beacon equipment that can be used by the vehicle must be provided.

Further, in the above-described technique (3), accurate speed information may not be obtained when the vehicle speed is low, and when the speed change of the vehicle is large, it takes time to process. Therefore, an error occurs in the calculated speed. Therefore, there is a problem that accurate correction may not be performed. In addition, GPS receivers and GPS that can be used in vehicles
It is necessary to provide an antenna. In addition, when the vehicle is in a tunnel or underpass, or in a traveling state such as a shadow of a building where GPS signals cannot be received, there is also a problem that a GPS satellite cannot be used and correction cannot be performed.

Therefore, the present applicant has previously filed Japanese Patent Application No. 7-97.
In No. 197, the distance coefficient can be accurately corrected and the vehicle position can be obtained with high accuracy regardless of the characteristics of the road on which the vehicle travels or the traveling speed of the vehicle, and without requiring special equipment. A current position calculation device is proposed.

In this prior art, by comparing the road shape of the road map, particularly the road direction with the vehicle direction,
The correction information of the distance coefficient is sought. However, at highway or toll road interchanges, etc., the road shape on the road map does not always match the actual road shape and is uncertain, so the correction information obtained at such places If the distance coefficient is corrected, the error of the distance coefficient may be increased.

Therefore, it is an object of the present invention to provide a current position calculating device capable of preventing the distance coefficient from being erroneously corrected in a place where the road shape is uncertain.

[0015]

[Means for Solving the Problems] To achieve the above object,
The present invention is mounted on a vehicle that moves with the rotation of wheels,
A current position calculating device for calculating the current position of the vehicle, which stores map data representing a road map, a traveling azimuth detecting unit that detects a traveling azimuth of the vehicle, and a rotation speed that detects a rotation speed of a wheel. Detecting means, mileage calculating means for calculating the mileage of the vehicle according to the rotation speed of the wheels detected by the rotation speed detecting means, and the set distance coefficient, and the mileage calculating means. The road on which the vehicle exists and the current position of the vehicle on the road are estimated according to the traveling distance of the vehicle, the traveling direction of the vehicle detected by the traveling direction detecting means, and the map data representing the road map. Means for determining the road vehicle heading difference between the road heading at the estimated current position and the traveling heading of the vehicle for each predetermined traveling distance, and the road vehicle heading difference is almost continuously maintained at a predetermined value or more. During a certain period, means for accumulating the road vehicle heading difference, and when the road vehicle heading difference ceases to be in a state of being above a predetermined value almost continuously, based on the accumulated road vehicle heading difference, First distance coefficient correction means for generating a short-term correction variable for correcting the distance coefficient in the short term, and for correcting the distance coefficient in the long term based on the contribution to the traveled distance by the correction of the distance coefficient. A second distance coefficient correction means for generating a long-term correction variable of the above, and a means for detecting entry from a general road to an expressway based on the estimated current position and the map data, When there is an opportunity to calculate the contribution to the traveling distance by the correction of the distance coefficient after entering the expressway, the distance coefficient correcting means of 0 sets the contribution to 0. Characterized by Provides the current position calculating device.

In this device, the first distance coefficient correction means preferably determines the sign of the short-term correction variable based on the sign of the accumulated road vehicle heading difference and the sign of the accumulated road heading difference. At the same time, the absolute value of the short-term correction variable is determined based on the accumulated absolute value of the road vehicle heading difference.

The second distance coefficient correcting means preferably accumulates, for each predetermined relatively long distance, the correction distances in which the long-term correction variable and the short-term correction variable contributed to the correction of the traveling distance, The long-term correction variable is generated based on the ratio of the accumulated correction distance and the predetermined relatively long distance.

The first distance coefficient correction means preferably sets the absolute value of the short-term correction variable to a value larger than an appropriate value when the short-term correction variable is set, and the short-term correction variable is set at a predetermined distance after the setting. The set value of the correction variable is changed to the value considered to be appropriate. In this case, the first distance coefficient correction means holds the old value when the short-term correction variable is set, and when the vehicle enters the highway, the appropriate value is set at a predetermined distance after the setting. The old value is used instead of the value considered to be.

As a result of the map matching processing, the second distance coefficient correction means preferably adds a new distance from a road which is considered to be currently traveling to a road different from a road connected to the front of the road. If the correct current position is determined,
When there is an opportunity to calculate the contribution to the traveling distance by the correction of the distance coefficient within the predetermined distance, the contribution is set to 0.

[0020]

When the distance coefficient has an error, the traveled distance obtained by the error also has an error. As a result, a deviation occurs between the current position obtained on the road map and the actual current position. Therefore, although the vehicle has not yet reached the curve of the actual road, the road direction at the current position on the map has begun to bend, or the vehicle has already reached the curve of the actual road and the vehicle direction has begun to bend. A situation occurs in which the current position on the road map is still on a straight road. In such a case, a continuous disagreement occurs between the road direction and the vehicle direction.

According to the present invention, the cumulative value of such road vehicle heading differences is obtained, error information corresponding to the error of the distance coefficient is further obtained, and the distance coefficient is corrected based on this error information. That is, the road vehicle heading difference between the road heading at the estimated position and the traveling heading of the vehicle is obtained for each predetermined traveling distance, and during the period in which the road vehicle heading difference is almost continuously equal to or more than a predetermined value, Accumulate road vehicle heading differences. Further, a road heading difference, which is a change amount of the road heading at the estimated position for each predetermined traveling distance, is obtained, and the road heading difference is determined during a period in which the road vehicle heading difference is continuously maintained for a predetermined value or more. Accumulate. When the road-vehicle azimuth difference is substantially continuous and is no longer equal to or greater than a predetermined value, the distance coefficient is corrected according to the accumulated road-vehicle azimuth difference.

At this time, by the first distance coefficient correcting means,
A short-term correction variable for correcting the distance coefficient in a short-term is generated based on the accumulated road vehicle heading difference when the road vehicle heading difference ceases to be more than a predetermined value almost continuously. At the same time, the second distance coefficient correction means generates a long-term correction variable for long-term correction of the distance coefficient based on the contribution to the traveled distance by the correction of the distance coefficient.

The second distance coefficient correcting means, after entering the highway (that is, after passing through the interchange),
When there is an opportunity to calculate the contribution to the traveling distance by correcting the distance coefficient up to a predetermined distance, the contribution is set to 0.

As a result, it is possible to prevent the distance coefficient from being erroneously corrected in a place where the road shape is uncertain. Further, as a result of map matching, if there is a jump of the current position to another road, that is, the map. As a result of the matching process, from the road that is considered to be currently running,
Even if a new current position is determined on a road different from the road connecting to the front of the road, the second distance coefficient correction means determines the distance up to a predetermined distance because the past accumulated data is uncertain. During this period, if there is an opportunity to calculate the contribution to the traveling distance by correcting the distance coefficient, the contribution is set to 0.

The second distance coefficient correction means accumulates, for each predetermined relatively long distance, the correction distances in which the long-term correction variable and the short-term correction variable during that time contribute to the correction of the traveling distance, and the accumulated distances are accumulated. The long-term correction variable is generated based on a ratio of a correction distance and the predetermined relatively long distance.

The first distance coefficient correcting means sets the absolute value of the short-term correction variable to a value larger than a value considered to be appropriate when the short-term correction variable is set, absorbs a traveling distance error, and travels a predetermined distance after the setting. At this point, the set value of the short-term correction variable is changed to the value considered to be appropriate. At this time, the first distance coefficient correction means holds the old value when the short-term correction variable is set, and when the vehicle enters the highway, a new distance is set at the time when the vehicle travels a predetermined distance after the setting. The old value is used as the short-term correction variable instead of the value considered to be appropriate. The same applies to the case where there is a position jump up to a predetermined distance when the vehicle travels a predetermined distance after the setting.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present position calculating device according to the present invention will be described below.

FIG. 1 illustrates the configuration of the present position calculating apparatus according to this embodiment.

That is, the present position calculating apparatus according to the present embodiment includes an angular velocity sensor 201 for detecting a change in the heading by detecting the yaw rate of the vehicle, and a geomagnetic sensor for detecting the heading of the vehicle by detecting the geomagnetism. Etc., and a vehicle speed sensor 203 that outputs pulses at time intervals proportional to the rotation speed of the output shaft of the transmission of the vehicle.

Further, a display 207 for displaying a map around the current position, a mark indicating the current position, etc., a switch 204 for receiving a command from the user (driver) to switch the scale of the map displayed on the display 207, and a digital map. A CD-ROM 205 for storing data,
A driver 206 for reading map data from the CD-ROM 205 is provided. Further, the controller 208 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, road width data indicating the road width of the road, and whether the road is a highway or a general road. A highway flag indicating whether there is any is included.

Next, the controller 208 converts the signal (analog) of the angular velocity sensor 201 into a digital signal and the A / D converter 209 which converts the signal (analog) of the azimuth sensor 202 into a digital signal. Bowl 210
And the number of pulses output from the vehicle speed sensor 203 is 0.1
A counter 216 that counts every second and a switch 204
Parallel I / O211 which inputs the presence or absence of pressing
-DMA (Direct Memory Access) controller 212 for transferring the map data read from the ROM 205
And a display processor 213 for displaying a map image on the display 207.

The controller 208 also has a microprocessor 214 and a memory 215.
The microprocessor 214 uses the signal of the angular velocity sensor 201 obtained via the A / D converter 209 and the A / D converter 21.
The signal of the direction sensor 202 obtained through 0, the counter 21
6, the number of output pulses of the vehicle speed sensor 203, the presence / absence of pressing of the switch 204 input via the parallel I / O 211, and the C obtained via the DMA controller 212.
The map data from the D-ROM 205 is accepted, processing is performed based on those signals, the current position of the vehicle is calculated, and the current position is displayed on the display 207 via the display processor 213. The display of the vehicle position is performed by superimposing an arrow mark or the like on the map already displayed on the display 207, as shown in FIG. This allows the user to know the current position of the vehicle on the map. The memory 215 is used as a work area when the microprocessor 214 performs a process, and a ROM that stores a program that defines the contents of a process (described later) for realizing such an operation, various tables described below, and the like. Includes RAM.

The operation of the present position calculating apparatus according to this embodiment will be described below.

First, three processes, that is, a process for calculating the traveling direction and the traveling distance of the vehicle, a process for determining the current position of the vehicle from the calculated traveling direction and distance, and a process for displaying the obtained vehicle position and direction are described. explain.

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

This process is carried out at a constant cycle, for example 100 m.
It is a routine of the microprocessor 214 that is activated and executed for each S.

In this routine, first, the A / D converter 2
The output value of the angular velocity sensor 201 is read from 09 (step 301). The output value of this angular velocity sensor 201 is
Since the bearing change is output, only a relative value in the traveling direction of the vehicle can be detected. Therefore, next, the A / D converter 2
10, the output value of the azimuth sensor 202 is read (step 302), and the vehicle is estimated using the absolute azimuth calculated from the output value of the azimuth sensor 202 and the azimuth change (angular speed output) output from the angular speed sensor 201. The azimuth is determined (step 303).

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 201 is large. Therefore, when the vehicle speed is low for a certain time or longer, the direction sensor 2
This is performed by using only the azimuth output by 02.

Next, the number of pulses output from the vehicle speed sensor 203 is counted by the counter 216 every 0.1 second, and the counted value is read (step 304). By multiplying this read value by the distance coefficient R, the distance advanced in 0.1 second is obtained (step 305). How to obtain the distance coefficient R will be described later.

Next, the traveling distance value per 0.1 second thus obtained is integrated with the value obtained last time,
It is checked whether or not the traveling distance of the vehicle has reached 20 m (step 306).
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 306), the traveling direction and traveling distance (20 m) at that time are output (step). 307). In step 307, the cumulative distance is further initialized, and the cumulative running distance is newly started.

Next, a process for obtaining the current position of the vehicle based on the calculated heading and traveling distance will be described.

FIG. 4 shows the flow of this processing.

This processing is a routine of the microprocessor 214 which is started and executed in response to the output of the traveling direction and the traveling distance from FIG. That is, this process is started every time the vehicle advances 20 m.

In this process, first, step 30
The traveling direction and the traveled distance output in 7 are read (step 401). Next, a map matching process is performed, and the current position on the road is calculated based on the current position and the traveling azimuth and traveling distance of the vehicle obtained in the previous process (step 402).

Then, it is checked whether or not the obtained present position is on the expressway (step 403). This can be determined by the above-mentioned highway flag included in the map data.

If it is on a general road, the cumulative traveling distance hw-1 on the expressway is set to 0 (step 405),
Control goes to step 409. If it is on an expressway, the traveling distance hw_l is updated (step 404).

It is checked whether or not the expressway travel distance hw_l is within 1 km (step 406). If it is within 1 km, the flag f1 is set to 1 (step 407). If it is less than 1 km, the flag f1 is set to 0. (Step 408).
This flag f1 is a flag for identifying the traveling up to a relatively short distance (here, 1 km) after entering the expressway from the general road. During the period when this flag is 1, that is, less than 1 km after entering the highway, a process different from the normal process is performed in the distance coefficient correction process described later.

In the present embodiment, an example will be described in which this processing is performed only when a general road is taken on an expressway. This is because there are generally few features of the road shape after riding on the expressway, so there are few opportunities to correct the distance coefficient, while there are many features of the road shape when descending from the reverse expressway to the general road. Therefore, it is considered that there are many opportunities for correction. However, as a matter of course, the present invention may be applied to the case of a highway to a general road.

Next, it is checked whether or not there is a jump in the current position (step 409). The position jump of the current position means that the current position on the road currently running is different from the road connected to the front of the current road as a result of the map matching processing in the previous step 402 for calculating the next current position. It means that the current position flies on the road. When such a position jump occurs, the position jump travel distance pos_l for accumulating the travel distances after the position jump is reset to 0 (step 410), and when there is no such position jump pos_l.
Is updated (step 411).

Then, it is checked whether the distance pos_l is 3 km or less and the flag f1 is 0 (step 412). If the result is Yes, the flag f1 is set to 1 (step 413). When the result is No, that is, when the traveling distance pos_l after the position jump exceeds 3 km, or when the flag f1 is already 1, the process jumps to step 414. Distance traveled after position jump p
Even if os_l is less than 3 km, the flag f1 is set to 1 because it is highly possible that the current position where the position has jumped will cause the position to jump again. This is because the coefficient correction process is performed differently from the normal process.

In the following step 414, a distance coefficient correction process which will be described in detail later is performed.

An example of the map matching process will be described with reference to FIG.

First, the traveling direction and the traveling distance are read (step 501). Based on these data, the movement amount 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 current position of the vehicle obtained in the previous processing to obtain the current position (A).
Is calculated (step 502).

If there is no previously obtained position, such as immediately after the start of the apparatus, the present position (A) is obtained by using the separately set position as the previously obtained position.

Next, the map around the obtained current position (A) is obtained from the CD-ROM 205 by the drivers 206 and D.
Via the MA controller 213, the road data (line segment) that is read out and within a preset distance D centered on the current position (A) is extracted (step 503).

The road data is, for example, as shown in FIG. 13, a plurality of line segments 81 to 85 connecting two points.
It is possible to use those which are approximated by and are expressed by the coordinates of the start point and the end point of these line segments. For example, the line segment 83 has its start point (x3, y3) and end point (x4, y4).
Try to express by.

Next, from the line segments extracted in step 503, only the line segments whose azimuth is within the predetermined traveling direction and the predetermined traveling direction are extracted (step 5).
04). Further, with respect to all the extracted line segments, a perpendicular is drawn from the current position (A) and the length of the perpendicular is obtained (step 505).

Next, using the lengths of these perpendiculars, the error cost values defined below are calculated for all the line segments extracted in step 504.

Error cost = α × | traveling direction−line segment direction | + β | perpendicular line length | where α and β are weighting factors. The values of these coefficients may be changed depending on which of the deviation between the traveling direction and the azimuth of the road and the deviation between the current position and the road is prioritized in selecting the road above the current position. For example,
When a road whose direction is close to the traveling direction is important, α is increased.

When the error cost of each line segment is calculated, the line segment having the smallest error cost value is selected from the line segments for which the error cost has been calculated (step 50).
6) The intersecting point of the selected line segment and the perpendicular (the foot of the perpendicular of the line segment) is set as the corrected current position (B) (step 507).

By the way, in the above-mentioned step 503,
Road data (line segment) within a preset distance D centered on the current position (A) was extracted.
May be a value determined based on the error cost value of the road selected in step 506 performed last time.

Here, the reason for obtaining the search range based on the error cost is that if the error cost is large, it is considered that the credibility with respect to the accuracy of the current position (B) obtained last time is low. This is because it is more appropriate to search for the road to find the correct current position.

Next, the processing for displaying the obtained vehicle position and azimuth will be described.

FIG. 6 shows the flow of this processing.

This process is a routine of the microprocessor 214 which is activated and executed every one second.

First, the parallel I / O 21 determines whether or not the switch 204 is pressed to instruct to change the map scale.
A judgment is made by looking at the contents of 1 (step 601). If it is pressed (Yes in step 601), a predetermined scale flag is set correspondingly (step 60).
2).

Next, the current position (B) obtained by the processing of FIG. 4 is read (step 603) and step 602.
A map having a scale according to the content of the scale flag switched in step S6 is displayed on the display 207 in the state as shown in FIG. 2, for example (step 604).

Then, the current position (B) of the vehicle and the traveling direction of the vehicle are superposed on the map, for example, as shown in FIG.
The arrow mark "↑" is used for display (step 605). Finally, the north mark indicating north and the distance mark corresponding to the reduced scale are displayed in a superposed manner as shown in FIG. 2 (step 606).

In the present embodiment, the vehicle position and direction are indicated by using the arrow symbols as described above, but the display form of the vehicle position and direction indicates 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.

Next, a method of obtaining the distance coefficient R used for calculating the distance in the processing step 305 of FIG. 3 will be described.

As described above, the traveling distance of the vehicle is obtained by multiplying the number of pulses output by the vehicle speed sensor 203 by the distance coefficient R. However, since the running distance of the vehicle per one rotation of the tire changes due to tire wear or the like, if the distance coefficient R is set to a fixed value, the distance cannot be accurately obtained with running. Therefore, in this embodiment, the current position (B) (step 402) obtained by the processing of FIG.
By comparing the road direction obtained from the map data read from 205 through the driver 206 with the vehicle direction (step 303) obtained by the processing of FIG. 3, the current position (B) becomes the actual position. The distance coefficient R is dynamically corrected by determining whether it is ahead or behind.

Such correction of the distance coefficient R can be performed as follows, for example.

That is, a correction variable Rsh for correcting the distance coefficient R in the short term and a correction variable Ra for correcting the distance coefficient R in the long term are introduced. Then, the distance coefficient R =
Distance coefficient R is dynamically calculated according to R0 × (1 + Ra + Rsh)
To fix. In addition, R0 has shown the initial value of the predetermined distance coefficient R here.

Then, the microprocessor 214 sequentially changes the correction variable Rsh and the correction variable Ra by the processing shown in FIGS. 7, 8 and 9. In the following, first, FIG.
The contents of the respective processes shown in FIGS. 8 and 9 will be described individually, and then, how the variables Rsh and Ra are changed by these processes in actual traveling of the vehicle will be described. .

First, when the apparatus is started, as initialization processing, the distances hw_l, pos_l and various variables and flags (f2, Σθ, Σ20θ, used in the processing of FIGS. 7, 8 and 9 described below, Σφ, D, Rsh, Ra, Σ
A, F1 to F10) are all initialized to 0.

The processing shown in FIG. 7 shows a detailed processing procedure of the distance coefficient correction processing 44 of FIG.

In this process, first, it is determined whether or not the flag f2 is 0. If it is not 0 (here, 1), the process proceeds to step 801 in FIG. 8 (step 701). on the other hand,
If the flag f2 is 0, the road direction where the current position (B) is located, which is obtained from the current position (B) output in step 402 of FIG. 4 and the map data read from the CD-ROM 205 to the driver 206. And step 40 in FIG.
The vehicle orientation (estimated orientation) output in 7 is read (steps 702, 703, 704).

Next, based on these values, the road vehicle heading difference θ which is the difference between the road heading where the current position (B) is located and the vehicle heading, the road heading obtained in step 703 of the previous processing, and the present time. The road orientation difference φ, which is the difference from the road orientation obtained in step 703 of the processing of step 703, is obtained (step 70
5). Here, whether the road orientation difference φ is positive or negative is positive when the road orientation obtained this time is on the left side with respect to the previous road orientation, and negative when it is on the right side. The positive / negative of the value of the road vehicle heading difference θ is, for example, positive when the vehicle heading is on the left side and negative when the vehicle heading is on the right side with respect to the road heading.

Next, it is checked whether the absolute value of the road vehicle heading difference obtained in step 705 is less than 3 deg (step 706) and if it is 3 deg or more (step 706).
If No.), the value obtained by adding the road vehicle heading difference θ to the road vehicle heading difference integrated value Σθ obtained in the previous processing is added to the new Σθ.
And a value obtained by adding a value obtained by multiplying the road-vehicle azimuth difference integral value Σ20θ obtained in the previous process by the road-vehicle azimuth difference θ by the mileage 20 m from the previous process to this process. A new value of Σ20θ is set, and the road azimuth difference φ obtained this time is added to the road azimuth difference integrated value Σφ obtained in the previous process.
Is added as a new Σφ value (step 712),
Go to step 801.

On the other hand, when the road vehicle heading difference θ is less than 3 deg (Yes in step 706), it is checked whether the absolute value of the current road vehicle heading difference integrated value Σθ is 5 deg or more (step 707), 5 deg. If it is less than (No in step 707), the road vehicle heading difference integrated value Σθ, the travel distance weighted road vehicle heading difference integrated value Σ2
After initializing 0θ and the road azimuth difference integral value Σφ to all 0,
Go to step 801.

Here, when the result in step 706 is Yes, it means that the road vehicle heading difference θ exceeding 3 deg has been interrupted for two or more times.

On the other hand, when the road vehicle heading difference integrated value is 5 deg or more (Yes in step 707), the correction variable Rs is set in steps 708, 709, and 710.
Perform processing for changing h.

At step 708, a value obtained by adding the value obtained by multiplying Ra + Rsh by the distance variable D to the value of ΣA at that point is set as a new ΣA, and the distance variable D is initialized to 0. ΣA
Is a value obtained by weighting the value of Ra + Rsh with the distance traveled by the value of Ra + Rsh, and corresponds to the contribution to the traveled distance by the correction of the distance coefficient. The distance variable D always represents the distance traveled by the vehicle after the distance variable D was initialized to zero. This distance is also obtained by multiplying the number of pulses output from the vehicle speed sensor 203 by the distance coefficient R. In step 708, Rsh at that time is saved as the old value Rshp.

Next, at step 709, it is determined from the road azimuth difference integrated value Σφ whether the traveling road is a right turn or a left turn while the road vehicle azimuth difference θ exceeding 3 deg continues. This judgment is based on the road heading difference integrated value Σ
If φ is positive, it is determined to be a left turn, and if it is negative, it is determined to be a right turn.

Next, at step 710, the mileage weighted road vehicle heading difference integrated value Σ20θ and step 7
The correction variable Rsh is corrected according to the right / left turn determined in 09. The method of this correction will be described.

FIG. 10 shows a case where the traveling road is a left turn while the road vehicle heading difference θ exceeding 3 deg is continuous,
For each of the right turn, the road, the current position (B), and the road vehicle heading difference θ when the traveling distance weighted road vehicle heading difference integrated value Σ20θ is positive and negative
Is represented.

Here, the state 1 in FIG. 10 indicates a left turn, in which the traveling distance weighted road vehicle heading difference integrated value Σ20θ is positive, that is, the road vehicle heading difference integrated value Σθ is positive. The current position (B) is behind the actual position. This is because the vehicle actually makes a left turn before the current position (B) reaches the left turn position. State 2 shows a case where the vehicle turns left and the mileage-weighted road vehicle heading difference integrated value Σ20θ is negative.
In this case, the current position (B) is ahead of the actual position. This is because the current position (B) has reached the position of turning left, but the vehicle is not actually turning left.

The same can be considered in the case of a right turn, and the traveling distance weighted road vehicle heading difference integrated value Σ20θ in state 3 is used.
When is negative, the current position (B) is behind the actual position. If the mileage-weighted road vehicle heading difference integrated value Σ20θ in state 4 is positive, the current position (B)
Is ahead of the actual position.

Therefore, as shown in FIG. 11, depending on whether the traveling distance weighted road vehicle heading difference integrated value Σ20θ is positive or negative, and whether the variable Ta for correcting the correction variable Rsh is positive or negative, as shown in FIG. Establish. Then, the magnitude of the absolute value of the variable Ta is determined according to the magnitude of the absolute value of the traveling distance weighted road vehicle heading difference integrated value Σ20θ. The magnitude of the absolute value of the variable Ta is determined according to the table A prepared in advance. Table A is a table in which correspondence between the magnitude of the absolute value of the traveling distance weighted road vehicle heading difference integrated value Σ20θ and the magnitude of the absolute value of the variable Ta is described. In step 710, the variable T thus obtained is calculated.
The value of the variable Ta is determined based on the magnitude of the absolute value of a and whether the variable Ta is positive or negative. Then, Rshp stored in step 708, that is, the correction variable Rsh up to now is changed to the variable T.
A new Rsh is obtained by adding the values of a. Also, R
When sh is modified, flag f2 is set to 1.

When step 710 is completed, in step 711, the road vehicle heading difference integrated value Σθ, the travel distance weighted road vehicle heading difference integrated value Σ20θ, and the road heading difference integrated value Σφ are all initialized to zero.

Next, the processing shown in FIG. 8 is performed.

In this process, first, in step 801,
The distance variable D is 300 m or more, and the flag f2
Is 1 is determined. The distance variable D will exceed 300 m if the vehicle travels 300 m or more after D is initialized to 0 in step 708 of the figure. 300 m
If it is less than or equal to 0 or the flag f2 is 0, the process jumps to step 805. On the other hand, when it is 300 m or more and the flag f2 = 1 (that is, when the distance D becomes 300 m or more for the first time after the processing of steps 708 to 710 in FIG. 7), the value of ΣA at that time is Ra + Rsh. Is added to a value obtained by multiplying the distance variable D (here, about 300 m) by the new value ΣA (step 802). However, if the flag f1 is 1 at this time, ΣA = ΣA. That is, ΣA is not updated. This results in step 710 of FIG.
Even though Rsh is updated in step S1, the contribution to the traveled distance by the distance coefficient correction by that Rsh is not considered here.

Next, Rsh is corrected using Table B prepared in advance (step 803). That is, the absolute value of the variable Tb is obtained according to the table B, and the variable Tb is set so that the positive / negative of the variable Ta and the positive / negative of the variable Tb match.
Determine the sign of. Table B describes the correspondence between the absolute value of the variable Ta and the absolute value of the variable Tb. This correspondence is set so that the value of the absolute value of the variable Ta that decreases at a predetermined rate becomes the absolute value of the variable Tb. Specifically, the variable Ta is set to a value that is about one digit larger than the corresponding variable Tb. Then, a new Rsh is obtained by adding the value of the variable Tb to the Rshp stored in step 708 of FIG. 7, that is, the correction variable Rsh before Rsh is modified in step 710. However, also in this case, if the flag f1 is 1, Rsh is not updated, that is, Rsh is not updated.
Let sh = Rshp. Then, the flag f2 and the distance variable D are initialized to 0 (step 804).

Then, it is checked whether the distance D is 10 km or more (step 805). If it is less than 10 km, the process is terminated, and if it is more than 10 km, the correction variable Ra is updated (step 806). Details of the Ra update processing will be described below with reference to FIG.

The processing of FIG. 9 is a routine of the microprocessor 214 which is started and executed every time the vehicle advances 10 km. This 10 km is obtained by multiplying the number of pulses output by the vehicle speed sensor 203 by the distance coefficient R.

In this processing, first, a value obtained by adding a value obtained by multiplying Ra + Rsh by the distance variable D to the value of ΣA at that time is set as a new ΣA (step 901). And 10
The nine variables F1 to F9 that store ΣA for each km are shifted one by one to become variables F2 to F10 (step 90
2), the variable F1 is calculated according to the following formula (step 9)
03).

F1 = {(ΣA + 10 km) / 10 km} −1 Then, in step 904, the values of the variables F1 to F10 are averaged, and this value is used as the correction variable Ra for the following steps.

Finally, each variable ΣA, Σ20θ, Σ
All of φ, Rsh, Σθ, D, and the flag f2 are initialized to 0, and the process ends (step 905).

The contents of the processing for changing the correction variable Rsh and the correction variable Ra have been described above. Below,
How the variables Rsh and Ra are changed by these processes in the actual traveling of the vehicle will be described.

Now, assume that the vehicle is traveling on a road as shown in FIG.

At the point a in the figure, the processing of FIG. 9 is executed, the correction variable Ra is changed, and the variables ΣA and Σ20 are changed.
It is assumed that θ, Σφ, Rsh, Σθ, D, and flag f2 are all initialized to 0. Further, the flag f1 is also set to 0. After that, from the point a to the point b, it is assumed that the road vehicle heading difference θ calculated in step 705 of the process of FIG. 7 started every 20 m is less than 3 deg. Then, a
7 to the point b, it is determined in step 706 in FIG. 7 that the road vehicle heading difference θ is less than 3 deg, and in step 707 that Σθ is less than 5 deg, the variables ΣA, Σ20θ, and Σφ. , Rsh, Σθ,
The flag f2 is initialized to 0 again in step 711.
Therefore, these variables are not changed at all. on the other hand,
The distance variable D also increases according to the traveling distance during this period. Next, in the section of 20 m from the point of b to c, the road vehicle direction difference θ becomes 4 deg, and 20 from the point of c to the point of d.
It is assumed that the road vehicle heading difference θ is less than 3 deg in the section m. In this case, it is determined that the road vehicle heading difference θ is 3 deg or more in step 706 of the processing of FIG.
In, the variables Σ20θ, Σφ, Σθ are updated according to the road vehicle azimuth difference θ and the road azimuth difference φ in the 20 m section. However, in the processing of FIG. 7 executed at a point d after traveling 20 m, it is determined that the road vehicle heading difference θ is less than 3 deg and the road vehicle heading difference integrated value Σθ is 5 deg or less, so the variables ΣA, Σ20 θ, Σφ , Rsh, Σθ,
The flag f2 is initialized to 0 again in step 711.

As described above, in the processing of FIG. 7, the road vehicle heading difference θ is less than 3 deg and the road vehicle heading difference integrated value Σθ is 5 degrees.
If it is less than deg, the variables ΣA, Σ20θ, Σ
Initialize φ, Rsh, Σθ, and flag f2. this is,
Road vehicle heading difference θ less than 3 deg or road vehicle heading difference θ that is 3 deg or more and less than 5 deg only once without being continuous.
Is considered to be an error due to a factor other than an error in the distance coefficient R, and these road vehicle heading differences are ignored in correction of the correction variables Rsh and Ra performed in a later process. Is.

Next, it is assumed that the road vehicle heading difference θ becomes 3 deg or more from the point d to the point e twice or more continuously. In this case, in step 712 of the processing of FIG. 7 executed between these points, the variables Σ20θ, Σφ,
Σθ is updated. As a result, at point e, Σφ is d
Represents the integrated value of the road heading difference φ obtained between the points e to e, Σθ represents the integrated value of the road vehicle heading difference θ found between the points d to e, and Σ20θ represents the point d from the e It means that the integrated value of the value obtained by weighting the traveling distance to each road vehicle heading difference θ obtained between the two is represented.

Next, 20 m from point e to point f
It is assumed that the road vehicle heading difference θ in the section is 3 deg or less.

In this case, the road vehicle heading difference θ is determined to be 3 deg or less at step 706 of the process of FIG. 7 executed at the point f traveling 20 m from the point e, and the road vehicle heading difference integrated value is determined at step 707. Σθ is 5 de
Since it is determined to be g or more, Rsh is updated according to Σ20θ, Σφ as described above in steps 709 and 710. In addition, the distance from the point a to which the distance variable D is initialized in step 708 to the point f is the sum of the correction variables Ra and Rsh (Ra + Rsh) used during this time, which is the distance variable D that represents this point. The value multiplied by is added to ΣA (0 at this point). This ΣA is
It is used later to obtain Ra in the process of FIG. Then, the distance variable D is initialized to 0. Further, the flag f2 is set to 1 in step 710. As a result, the process of FIG. 8 is substantially skipped according to the determination in step 701 until the process of FIG. 8 is executed and the flag f2 is cleared to 0 at the point of time g after traveling 300 m thereafter. Then, Σ20θ, Σθ, and Σφ obtained to obtain Rsh in steps 709 and 710 are obtained in step 7
Initialized to 0 at 11.

Next, at the point g which has traveled 300 m after the distance variable D was initialized to 0 at the point f, it is determined in step 801 in FIG. 8 that the distance variable D is 300 m or more. And after Rsh is changed at the point of f,
Sum of correction variables Ra and Rsh used up to now (Ra +
A value obtained by multiplying the distance variable D by Rsh) is added to ΣA, and Rsh is corrected in step 803 as described above.
As a result, 300m from the point f to the point g is f
The traveled distance is obtained using Rsh obtained at the point
After the point of, the value smaller than Rsh obtained at the point of f is used as a new Rsh.

As a result, the initial 300 m exceeds the value which seems to be correct in the direction of correcting the distance coefficient R intentionally by making the absolute value of the correction variable Rsh larger than the value which seems to be appropriate. The deviation of the current position (B) accumulated between c and d is corrected little by little while advancing this 300 m, and then the absolute value of the correction variable Rsh is reduced to make the distance coefficient R correct. You can reset the value to what you think. The reason why the deviation of the current position is gradually corrected over 300 m is to allow the display position of the current position to move smoothly without jumping or the like. Further, the reason why the process of FIG. 5 is substantially not executed during the 300 m is that the process of FIG. 5 is appropriate while the vehicle is traveling with the distance coefficient R intentionally displaced from a value that is considered to be correct. This is because it does not operate to obtain Rsh.

Thereafter, in the process of FIG. 8, step 804
Then, the flag f2 and the distance variable D are initialized to 0. When the flag f2 is initialized to 0, the process of FIG. 7 can be operated again according to the road vehicle heading difference θ as in the section from a.

After this, the vehicle traveled 10 km from point a, h
When the point is reached, the processing of FIG. 9 is executed. In this processing, first, the sum (Ra + Rsh) of the correction variables Ra and Rsh that have been used up to now is calculated as the distance variable D (finally step 70
The value obtained by multiplying ΣA by 8 or 802 (representing the distance from ΣA) is added to ΣA (step 901). As a result, ΣA is an integrated value of values obtained by weighting each (Ra + Rsh) used for 10 km from a to f to the traveling distance for which (Ra + Rsh) was effective.

Next, as initial values, F (1) to F (1
The element data F (9) of the array data F in which all the element data up to 0) are 0 and F (8) are F
(9) ,. ． ． , F (1) to F (2), and so on, so that F (n) is shifted one by one (step 902). Then, in step 903, {(ΣA + 10 km) / 10 k
Let m) -1 be F (1). Where {(ΣA + 10
k) / 10k} -1 is 10k measured from a to f
The value is approximately proportional to the ratio of the distances corrected by the influence of Ra and Rsh contained in m. Therefore, F (10) to F obtained in step 904
The average of the values of (1) is R, which is included in the past 100 km.
The value is approximately proportional to the ratio of the distance corrected by the influence of a and Rsh. Therefore, a value obtained by taking this average is set as a new Ra. Alternatively, a value obtained by multiplying the averaged value by an appropriate constant is set as a new Ra, and each variable Σ
A, Σ20θ, Σφ, Rsh, Σθ, D, and flag f2 are all initialized to 0.

Thereafter, the processing is repeated in the same manner as the processing from the point a.

In addition to the above-described principle of operation, it is assumed that there is an interchange on a highway, for example, on the way of the road, and the highway is approached from there. As a result, the highway travel distance hw_l is updated in step 404 of FIG. 4, and the flag f1 is set to 1 while this is less than 1 km. At the interchange, road vehicle heading difference θ
If the absolute value of the cumulative value of 5 becomes 5 deg or more, steps 708 to 711 of FIG. 7 are executed. After that, when the distance D in FIG. 8 becomes 300 m or more, ΣA is not updated (step 802), and Rsh is the old value Rsh.
It remains p (steps 802 and 803). As a result, the use of error information obtained at a place where the road shape is uncertain, such as an interchange, is suppressed.

Although not shown in the figure, if there is a jump in the current position, the same exception processing is performed up to 3 km thereafter.

As described above, since the variable Ta has a value that is larger by one digit than the corresponding variable Tb, the variable Ta obtained in step 710 is a value that is larger by one digit than Rsh. Therefore, step 7
In 10, the variable Ta itself may be processed as a new Rsh.

As described above, the error of the distance coefficient R used for obtaining the traveling distance is estimated from the difference between the road direction and the vehicle direction, and when there is an opportunity to correct the error, the road shape By suppressing the use of the error information for distance correction in an uncertain place, it is possible to prevent incorrect correction of the distance coefficient.

[0117]

As described above, according to the present invention, it is possible to provide a current position calculation device capable of preventing the distance coefficient from being erroneously corrected in a place where the road shape is uncertain.

[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 performed in an embodiment of the present invention.

FIG. 3 is a flowchart showing a procedure of a process of calculating a traveling azimuth and a traveled distance in one embodiment of the present invention.

FIG. 4 is a flowchart showing a procedure of current position calculation processing performed in an embodiment of the present invention.

5 is a flowchart showing a procedure of a map matching process shown as one step in FIG.

FIG. 6 is a flowchart showing a procedure of display processing performed in an embodiment of the present invention.

7 is a first flowchart showing a procedure of distance coefficient correction processing shown as one step in FIG. 4. FIG.

FIG. 8 is a second flowchart showing a procedure of distance coefficient correction processing.

9 is a flowchart showing a procedure of Ra update processing shown as one step in FIG.

FIG. 10 is a diagram showing a road vehicle heading difference determined in an embodiment of the present invention.

FIG. 11 is a variable Ta calculated in one embodiment of the present invention.
It is a figure showing how to determine the positive and negative of.

FIG. 12 is a diagram showing a road to which a process of correcting a distance coefficient is applied in the description of the embodiment of the present invention.

FIG. 13 is a diagram showing an expression format of roads in map data used in an embodiment of the present invention.

[Explanation of symbols]

 201 Angular velocity sensor 202 Direction sensor 203 Vehicle speed sensor 204 Switch 205 CD-ROM 206 CD-ROM driver 207 Display 208 Controller

Claims (6)

[Claims] 1. A current position calculating device which is mounted on a vehicle that moves as wheels rotate and calculates the current position of the vehicle, comprising means for storing map data representing a road map, and a traveling direction of the vehicle. Traveling direction detecting means for detecting, rotational speed detecting means for detecting rotational speed of the wheel, rotational speed of the wheel detected by the rotational speed detecting means, and a traveling distance of the vehicle in accordance with a set distance coefficient. According to the traveling distance calculating means for calculating, the traveling distance of the vehicle calculated by the traveling distance calculating means, the traveling azimuth of the vehicle detected by the traveling azimuth detecting means, and map data representing the road map, the vehicle is Means for estimating the existing road and the present position of the vehicle on the road, and a road vehicle heading difference between the heading of the road and the heading of the vehicle at the estimated present position is a predetermined traveling distance. And a means for accumulating the road vehicle heading difference during a period in which the road vehicle heading difference is substantially continuous and is a predetermined value or more, and the road vehicle heading difference is almost continuously a predetermined value or more. When the state disappears, first distance coefficient correction means for generating a short-term correction variable for short-term correction of the distance coefficient based on the accumulated road vehicle heading difference, and correction of the distance coefficient. Second distance coefficient correction means for generating a long-term correction variable for long-term correction of the distance coefficient based on the contribution to the travel distance, and general, based on the estimated current position and the map data Means for detecting entry from a road to an expressway, wherein the second distance coefficient correction means changes the travel distance to the travel distance by the correction of the distance coefficient within a predetermined distance after entering the expressway. The contribution If there is an opportunity to leave the current position calculating device, characterized in that the 0 the contribution. 2. The current position calculation device according to claim 1, wherein the first distance coefficient correction means uses the sign of the accumulated road vehicle heading difference and the sign of the accumulated road heading difference. A current position calculation device that determines the sign of the short-term correction variable based on the above, and also determines the absolute value of the short-term correction variable based on the accumulated absolute value of the road vehicle heading difference. 3. The current position calculation device according to claim 1, wherein the second distance coefficient correction unit corrects the long-term correction variable and the short-term correction for each predetermined relatively long distance. A current position characterized by accumulating a correction distance in which a variable contributes to the correction of the travel distance, and generating the long-term correction variable based on a ratio of the accumulated correction distance and the predetermined relatively long distance. Calculator. 4. The current position calculation device according to claim 1, 2, or 3, wherein the first distance coefficient correction means sets the absolute value of the short-term correction variable to an appropriate value when setting the short-term correction variable. The present position calculation device is characterized in that the set value of the short-term correction variable is changed to a value considered to be appropriate at a time point after traveling for a predetermined distance after the setting. 5. The current position calculation device according to claim 4, wherein the first distance coefficient correction means holds the old value when setting the short-term correction variable so that the vehicle enters the highway. In this case, the current position calculation device is characterized in that the old value is used in place of the value considered to be appropriate when the vehicle travels a predetermined distance after the setting. 6. The current position calculation device according to claim 1, wherein the second distance coefficient correction means selects a road from a road which is considered to be currently traveling as a result of the map matching process. When a new current position is determined on a road different from the road connecting to the front, and when there is an opportunity to calculate the contribution to the mileage by correcting the distance coefficient within a predetermined distance. The present position calculating device is characterized in that the contribution is set to 0.