JPH08292047A - Current position computing device - Google Patents

Abstract

PURPOSE: To properly correct a distance coefficient used for seeking a travel distance. CONSTITUTION: A microprocessor 214 seeks a vehicle travel distance in multiplying a distance coefficient to the count number made up of factoring a pulse number to be outputted by a car speed sensor 20 with a counter 216. In addition, a current position on a road is estimated from map data read out of a CD-read- only memory 205 via a driver 206, each of measured data of an angular velocity sensor 201, an azimuthal sensor 202 obtained via two analog-to-digital converters 209, 210, and a travel distance of the sought vehicle distance. In succession, the distance coefficient is dynamically corrected according to a difference between a travel state in case of having the estimated current position suited and another travel state shown by measured data of respective sensors. When the estimated current position skips to a position being not continuous and it is bent as far as almost 90 degrees at an intersection or the like, however, the compensation so far applied to the distance coefficient is canceled, and this distance coefficient is corrected by the value having considered the degree of reliability in the correction applied in the past, anew.

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 traveling on a road such as an expressway, since the road does not have features such as curves and intersections that can be used for map matching, it is impossible to sufficiently correct the error.

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, according to the present invention, the distance coefficient is accurately corrected regardless of the characteristics of the road on which the vehicle is traveling or the traveling speed of the vehicle, and without the need for special equipment, so that the vehicle position can be accurately adjusted. It is an object of the present invention to provide a current position calculation device capable of obtaining

[0013]

[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, a means for storing map data representing a road map, a means for detecting the traveling direction of the vehicle, a means for detecting the rotational speed of the wheels, A travel distance calculating means for calculating a travel distance of the vehicle in accordance with the detected rotation speed of the wheel and a set distance coefficient, a travel distance of the detected vehicle, a detected traveling direction of the vehicle, and the map. A means for estimating the road on which the vehicle exists and the position of the vehicle on the road according to the road map represented by the data, and a case where the vehicle is traveling on the estimated position of the vehicle on the road. A correction amount obtained according to the amount of deviation between the traveling condition and the detected traveling direction, or the traveling condition of the vehicle represented by the detected traveling direction and the calculated traveling distance, the distance set in the traveling distance calculating means. coefficient The distance coefficient correcting means has a distance coefficient correcting means for correcting, and the distance coefficient correcting means, when a position which is not continuous with a previously estimated position where the vehicle exists is estimated as a position where the vehicle exists, or the vehicle moves to the right at a substantially right angle. When turning left, the distance coefficient set in the travel distance calculating means is changed so that the correction amount of the correction applied to the distance coefficient up to that time is canceled, and the distance coefficient is applied until then. There is provided a current position calculation device characterized by performing an amount correction that is obtained according to a correction amount of each correction that has been effective for a certain degree or more in order to eliminate the deviation amount among the corrections.

[0014]

In the present position calculating apparatus according to the present invention, the traveling condition when the vehicle is traveling at the estimated position of the vehicle on the road, the detected traveling direction, or the detected traveling direction. And a correction amount determined according to the amount of deviation from the running condition of the vehicle represented by the calculated running distance, and the distance coefficient set in the running distance calculating means.

Further, when the position where the vehicle exists and the position which is not continuous with the position where the vehicle exists is estimated as the position where the vehicle exists, or when the vehicle makes a right / left turn in a substantially vertical direction, it is set in the traveling distance calculation means. In order to cancel the correction amount of the correction applied to the distance coefficient so far, and to cancel the deviation amount among the corrections applied to the distance coefficient until then. The amount correction is performed according to the correction amount of each correction that has been effective over a predetermined level.

[0016]

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.

Also, a display 207 for displaying a map around the current position, a mark indicating the current position, etc., a switch 204 for accepting a command for switching the scale of the map displayed on the display 207 from the user (driver), 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.

Next, the controller 208 has an A / D converter 209 for converting the signal (analog) of the angular velocity sensor 201 into a digital signal and an A / D converter for converting 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 further includes 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 through the parallel I / O 211, and the C obtained through 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 and displaying 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 stores a program that defines the contents of processing (described later) for realizing such operations, a ROM that stores various tables described below, and a work area when the microprocessor 214 performs the processing. And RAM used as.

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

First, the three processes of the process of calculating the traveling direction and traveling distance of the vehicle, the process of determining the current position of the vehicle from the calculated traveling direction and distance, and the process of displaying the obtained vehicle position and direction. explain.

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

This processing 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 401). 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 402), 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 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 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 404). By multiplying the read value by the distance coefficient R, the distance advanced for 0.1 second is obtained (step 405). 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 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 accumulated distance is further initialized and the accumulated traveling 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 40
The traveling direction and the traveled 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 current position of the vehicle obtained in the previous process to obtain the current position (A) (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. 6, approximated by a plurality of line segments 81 to 85 connecting two points, and these line segments are represented by the coordinates of their start points and end points. Etc. can be used. For example, line segment 8
3 is represented by its start point (x3, y3) and end point (x4, y4).

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). In addition, a point where each line segment intersects with the perpendicular (the foot of the perpendicular of the line segment) is set as a candidate point. Next, by using the lengths of the perpendiculars, for all the candidate points obtained in step 504, Calculate the error cost value defined below.

Error cost = α × | travel direction−line segment azimuth | + β | perpendicular 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 candidate point having the smallest error cost value is selected from the line segments for which the error cost has been calculated (step 50).
6) The selected candidate point 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.

The present position (B) may be obtained as follows.

That is, first, a candidate point is obtained from a certain position as described above. Then, the current position (B) is obtained from each of the candidate points as described above. Then, for the next current position (B), each candidate point obtained last time is set as the position obtained last time, and the candidate point for each is obtained,
The current position (B) is obtained from all the obtained candidate points. Hereinafter, similarly, each candidate point obtained last time is set as the position obtained last time, and the current position (A) for each is obtained.
Is calculated, a candidate point is calculated from each calculated current position (A), and the current position (B) is calculated from all the calculated candidate points. Therefore, in this case, each candidate point for the next time is obtained with reference to a candidate point different from the candidate point selected as the current position (B) last time.
In addition, the next current position (B) may be obtained based on a candidate point different from the candidate point selected as the current position (B) last time.

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

FIG. 5 shows the flow of this processing.

This processing 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 heading of the vehicle are superimposed 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 this 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 is as follows.
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 405 of FIG. 3 will be described.

As described above, the traveling distance of the vehicle is
It is calculated by multiplying the number of pulses output by the vehicle speed sensor 203 by the distance coefficient R. However, since the traveling distance of the vehicle per one rotation of the tire changes due to tire wear or the like, the distance coefficient R
If is a fixed value, the distance cannot be accurately determined as the vehicle travels. Therefore, in the present embodiment, the current position (B) (step 508) obtained by the processing of FIG.
-By comparing the road direction obtained from the map data read from the ROM 205 via the driver 206 with the vehicle direction (step 403) 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, the three correction variables Rsh, Ra,
Introduce Rshcb. Then, the distance coefficient R = R0 ×
The distance coefficient R is dynamically corrected according to (1 + Ra + Rsh + Rshcb). In addition, R0 has shown the initial value of the predetermined distance coefficient R here. In addition, the correction variable Ra
Rsh is for correcting the distance coefficient R in the short term, and is for correcting the distance coefficient R in the long term in accordance with the Rsh obtained while traveling for 10 km. Further, Rshcb is for correcting R only by an amount corresponding to the certainty of the obtained Rsh when it is judged that it is not appropriate to use the Rsh that has been obtained so far for obtaining Ra. Is.

Now, these correction variables Rsh and Rshc
b and Ra are sequentially changed by the microprocessor 214 executing the following processing.

In the following, first, the contents of this processing will be explained individually, and thereafter, in actual traveling of the vehicle,
By these processes, how is the correction variable Rshc
b, how the correction variable Rsh and the correction variable Ra are changed will be described.

First, an outline of how to obtain the correction variable Rsh will be described.

The correction variable Rsh is determined according to the actual turning of the vehicle at the curve of the road.

For example, it is assumed that the current position (B) output at step 508 in FIG. 4 is traveling on the road A in FIG. On the other hand, for example, of the current position (B) that is sequentially output, the current position of the vehicle obtained from the traveling distance of the traveling direction of the vehicle with reference to point a, which is a predetermined distance before the on-curve start point o. It is assumed that the locus is a locus that starts to bend from the point where point o is exceeded as shown by the broken line in the figure.

In this case, it can be estimated that the distance coefficient R is larger than the true value. This is because, at the time when it is estimated that the vehicle has reached the curve using the distance coefficient R, it is considered that the vehicle has not actually reached the curve because the vehicle has not started to bend. Also,
The degree to which the distance coefficient R is larger than the true value can be estimated from the distance d in the figure, which represents the distance between the point where the vehicle actually starts to bend and the curve start point o.

On the contrary, when the locus of the current position of the vehicle obtained from the traveling distance of the traveling direction of the vehicle is a locus that starts to bend before reaching the intersection o, the distance coefficient R is a true value. It can be estimated that it was smaller. This is because it is considered that the vehicle has already reached the curve o because the vehicle has started to bend before it is estimated using the distance coefficient R that the vehicle has reached the curve o.
Also in this case, the degree to which the distance coefficient R is smaller than the true value can be estimated from the distance error d in the figure showing the distance between the curve o and the point where the vehicle actually starts to bend.

Accordingly, it is possible to determine the direction of deviation of the distance coefficient from the true value and the degree thereof from d in the figure, and determine the correction variable Rsh so as to cancel it.

Alternatively, before the vehicle is estimated to reach the curve o using the distance coefficient R from the direction difference between the vehicle orientation and the road, the vehicle starts to bend or the vehicle reaches the curve o. The coefficient R may be used to determine whether the vehicle has begun to turn after being estimated. In this case, the degree to which the distance coefficient R deviates from the true value can be obtained from the integrated value of the vehicle heading and the road heading difference.

In this embodiment, in this way, when the distance error d is detected, the correction variable Rsh is obtained according to the value of the distance error d, and the distance coefficient R is corrected.

The distance coefficient R is corrected by the correction variable Rsh as follows.

That is, first, while traveling 300 m,
By making the absolute value of Rsh larger than the value for obtaining the correct R, the correct value is gradually obtained as the current position (B) during the traveling of 300 m. It is estimated that when the distance error d is obtained, an incorrect current position (B) is obtained due to an error in the distance coefficient up to that point. However, if the current position (B) is temporarily corrected to the correct position, the above-mentioned display mark of the current position moves in the direction opposite to the traveling direction or moves to a position away from the driver at once. Would be confusing. Therefore, while traveling 300 m, the absolute value of Rsh is made larger than the value for obtaining correct R,
The display position of the mark at the current position (B) is gradually corrected to the correct position while traveling.

After traveling 300 m, Rsh is corrected again to a value for obtaining the correct Rsh absolute value, and thereafter the current position (B) is obtained with the correct distance coefficient R. is there. Further, in the present embodiment, when the obtained Rsh is valid during the traveling for 2 km or more (when the new Rsh is not obtained), the Rsh is gradually reduced. This is because the case where the vehicle is valid during traveling for 2 km or more is that there is no curve for 2 km or more, and accordingly, the appropriateness of Rsh is not evaluated for 2 km or more. That is, in such a case, since the reliability of the appropriateness of Rsh is low, the value is gradually reduced so that its influence is reduced.

In the following, in order to facilitate understanding of the explanation, Rsh used during the traveling of 300 m is expressed as Rs.
h300 and Rsh obtained thereafter are represented by Rsh1.

Next, the correction variable Ra is Rsh1 and Rsh3 obtained during 10 km each time the vehicle travels 10 km.
It is a correction variable for correcting the distance coefficient R according to 00. The correction variable Rsh is calculated by Ra = {(10km + Lcom) / 10km} -1 by using the value Lcom obtained by weighting the travel distance for which the value was effective for each value of Ra + Rsh + Rshcb that changes sequentially during 10km. .

When Ra is obtained, Rsh1 or Rsh300, Rshcb that was valid up to that point is initialized to 0.

As described above, Ra is used to correct the distance coefficient R for every 10 km to a value obtained by approximately averaging the values of each R used during the 10 km. However, in the processing of FIG. 4, a position on the road different from the road on which the current position (B) existed is obtained as the current position (B), and the position is not continuous with the position of the previously estimated vehicle. When is estimated as the position where the vehicle exists, it can be estimated that Rsh1 and Rsh300 obtained up to that point are not correct. This is because Rsh1 and Rsh depend on the distance error d obtained between the vehicle and the curve of the road that is not actually traveling.
This is because there is a possibility that sh300 may be required.

As described above, the current position (B)
, The current position (B) is obtained from each of the candidate points, and the next current position (B) is set as the previously obtained position of each of the previously obtained candidate points.
When the current position (B) is obtained from all the obtained candidate points, the candidate point having the present position (B) obtained this time is the previously obtained present position (B). When the position is not the candidate point calculated as the position, the position obtained based on the position other than the position where the vehicle estimated previously is present is estimated as the position where the vehicle exists. Therefore, also in such a case, since the position where the vehicle estimated last time and the position which is not continuous are estimated as the position where the vehicle exists, it is estimated that Rsh1 and Rsh300 obtained up to that time are not correct. can do.

Similarly, when the vehicle turns through about 90 degrees (for example, 70 degrees to 110 degrees), Rsh
1 or Rsh300 may be obtained as a value greatly different from the value for obtaining the correct distance coefficient R. This is because, for example, at an intersection or the like having a plurality of lanes, a greatly different distance error d is obtained depending on which lane the vehicle travels and makes a turn, and thus a large error Rsh1 or Rsh300 is obtained depending on the turn. Is. Even when the vehicle bends at an angle smaller than approximately 90 degrees, a different distance error d is obtained depending on which lane the vehicle is traveling in and turns on a road having a plurality of lanes. It is smaller than when it is bent. Therefore, in this embodiment, the deviation and the influence when the vehicle bends at an angle smaller than approximately 90 degrees are allowed.

Therefore, in this embodiment, when a position which is not continuous with the previously obtained current position (B) is obtained as the current position (B) in the processing of FIG. 4 (when there is a position jump).
Or, when the vehicle bends by about 90 degrees, Lcom (Ra + Rsh + Rs) obtained up to that point since Ra was obtained last time
hcb) is a value obtained by weighting the traveled distance for which each value is effective, or Rsh1 or Rsh at that time.
Initialize sh300 and 10km from that point
Measure again.

However, in this way, since Ra is obtained last time, a position which is not continuous with the previously obtained current position (B) is obtained as the current position (B), or approximately 90.
Rsh1 and Rsh300 obtained by the time of turning
All the information on will be lost. Therefore, if this is done, for example, as shown in FIG. 8, even if the correct Rsh and Rsh300 have been obtained halfway, this experience cannot be reflected in the distance coefficient R thereafter. FIG. 8a shows that after the road branch point, the current position (B) is erroneously estimated on a road that is not actually traveling,
Current position (B) on the road actually running at point c
FIG. 8c is an example in which it has become possible to estimate
Is an example of turning right at an intersection after traveling for a while on a smoothly curving road.

Therefore, in this embodiment, the correction variable R is further added.
Since shcb was introduced and a position on the road different from the road where the current position (B) existed before was turned at the intersection, Lcom and Rsh1 or Rsh
When initializing 300, after obtaining Ra last time,
Of the Rsh300 obtained up to that point, that Rsh
For the Rsh300 for which the next Rsh300 was not obtained until the vehicle traveled for at least 2 km after obtaining 300, it is proportional to this Rsh300 and
Obtain a value that is sufficiently smaller than 300, and add this value to Rshcb
And the distance coefficient R is corrected by this value.

Hereinafter, each correction variable Ra, Rsh
In order to calculate 1, Rsh300, Rshcb,
Details of the processing performed by the microprocessor 214 will be described.

First, FIG. 9 shows an initialization process performed when the apparatus is activated.

In this processing, various variables d, La, Rsh (Rsh1 / Rsh300), R used in the subsequent processing are
a, Rshcb, l, lcom, i, Rshcb_dt
(I), Rsh0 is initialized to 0.

Next, FIG. 10 shows a process executed every time the vehicle travels 20 m after such an initialization process.

In this processing, each sensor 201, 202,
The traveling distance and the traveling direction calculated using 203 are read as sensor data (step 801). And then
The map data read by the driver 206 is read from the CD-ROM 205 (step 802).

Next, a variable La representing the traveling distance after the previous correction variable Ra was obtained, and a variable Lshcb (i- representing the traveling distance after the previous correction variable Rsh300 was obtained.
The value of 1) is updated by adding 20 m to the value at that time.

Next, it is determined whether the flag is 0 (step 804). The flag is a period during which Rsh300 is valid, that is, the distance error d is calculated.
It is a flag that has a value of 1 only while traveling 300 m after the calculation.

If the flag is 0, the above-mentioned distance error d is obtained. Then, the value of the variable Lsh representing the travel distance after the correction variable Rsh1 is obtained last time is updated by adding 20 m to the value at that time (step 806).

On the other hand, when the flag is 1, Rs
Steps 805 and 806 are not performed because the period in which h300 is valid, that is, the period in which the vehicle has not traveled 300 m after the distance error d is calculated and Rsh300 is calculated.

Next, the distance error d obtained in step 805
Is determined to be 0 (step 807). If the distance error d obtained in step 805 this time is not 0, and
Since the distance error d is not 0 while the Rsh 300 is valid, the Rsh calculation process of step 808 is performed. In addition, while Rsh300 is effective, this Rsh30
Since the distance error d used for obtaining 0 continues to be maintained, the distance error d does not become 0. In the Rsh calculation process (step 808), as described above, the calculation of Rsh300 and the calculation of Rsh300 to Rsh1 are performed. Further, in order to obtain the above-mentioned Rshcb later, a process of saving the value corresponding to the calculated Rsh300 in the array Rsh_dt is performed.

Next, at step 809, a variable Lsh representing the traveling distance after the correction variable Rsh1 was changed last time.
If it exceeds the value of 2 km, it is determined whether or not the value exceeds the value of 2 km, and if it exceeds, then Ra + Rsh + Rsh at that time is added to Lsh, which represents the distance traveled until the value of the correction variable Rsh1 was changed last time.
A value obtained by multiplying the value obtained by multiplying the value of cb by Lcom at that time is set as a new Lcom. This Lcom is used to calculate the correction coefficient Ra for each 10 km as described above.

Next, as described above, Rsh is gradually reduced from the value of Rsh1 in which the effective traveling distance exceeds 2 km.
Perform reduction processing. The Rsh reduction process is performed by subtracting a positive constant n from Rsh1 when Rsh1 is positive and adding it when Rsh1 is negative. However, positive Rs
If the value obtained by subtracting the constant n from h1 is a negative value,
Rsh1 is set to 0. If the value obtained by subtracting the constant n from the negative Rsh1 becomes a positive value, Rsh1 is set to 0. When the value of Rsh1 is 0, it remains 0.

Then, again, Lsh is reset to 0 in order to manage the effective distance of the reduced Rsh (step 812).

On the other hand, at step 809, the variable Lsh representing the traveling distance after the correction variable Rsh1 is changed last time.
If it is not determined that the value of does not exceed 2 km, the processes of steps 810 to 812 are not performed.

Next, at step 813, whether or not a position which is not continuous with the previously estimated current position (B) of the vehicle is estimated as the current position (B) in the processing of FIG. Or, it is determined whether the vehicle has turned around 90 degrees. Then, if neither, the processing ends.

On the other hand, in the processing of step 813, as the current position (B), the current position (B) is estimated to be a position which is not continuous with the previously estimated current position (B) of the vehicle, or approximately 90. When it is determined that the vehicle is bent, as described above, Lcom (each value of R is a value obtained by weighting the travel distance for which the value is valid) obtained up to that point, and The Rsh1 or Rsh300 is initialized, and La reset processing for re-measuring 10 km from that point is performed (step 814). Further, in this processing, as described above, R
A process of obtaining shcb and correcting the distance coefficient R is performed.

The details of each process will be described below.

First, the process of calculating the distance error d in step 805 will be described.

FIG. 11 shows the procedure of this processing.

As shown in the figure, in this process, first, it is judged whether or not the vehicle has turned right or left (step 1101),
It is determined whether a distance error exists (step 110).
2) If there is a distance error, the distance error d described above is calculated (step 1103). However, at this time, the sign of the distance error d is negative when the vehicle goes inside the curve, and the sign of the distance error d is positive when the vehicle goes outside the curve.

On the other hand, if the vehicle has not turned to the right or left, or if there is no distance error, the process ends.

Next, the process of calculating the correction variable Rsh in step 808 of FIG. 10 will be described.

FIG. 12 shows a processing procedure of the calculation processing of the correction variable Rsh.

In this process, it is first determined whether the flag is 0 (step 1201). When the flag is 0, Rsh300 is not effective and the non-zero distance error d is obtained (see FIG. 10).
A correction variable Rsh300 is obtained according to the distance error d (step 1203). However, before Rsh is changed,
Ra + Rsh + Rs at that time is added to Lsh that represents the distance traveled until the value of the correction variable Rsh1 was changed last time.
The value obtained by multiplying the value of hcb by the value of Lcom is set as a new Lcom. Also, Rs at that time
Store h1 as Rsh0 (step 120)
2). The correction variable Rsh300 is obtained from the distance error d as follows.

That is, the change d given to the correction variable Rsh
The sign of Rsh is determined by the correspondence shown in FIG. 13, and the absolute value of the change dRsh given to the correction variable Rsh is calculated by multiplying the absolute value of the distance error d by a predetermined coefficient j. And
Rsh300 = Rsh0 + dRsh according to Rsh300
Ask for.

Then, a value corresponding to the calculated size of Rsh300 is registered as Rch_dt (i) (step 1204), and the above-mentioned flag is set to 1 and Rs is set.
0 for the variable l that represents the distance traveled since h300 was calculated
Is set (step 1205) and the process ends. The variable l is used to determine whether or not the vehicle has traveled 300 m after Rsh300 was calculated.

Here, the registration of step 1205 is performed by referring to FIG.
The process shown in FIG. That is, it is determined whether or not the current i exceeds the number of elements of the array Rshcb_dt (step 1301). If there is more, there is no room to register this value in the array, and the process ends. On the other hand, if it does not exceed, the value obtained by multiplying the predetermined constant of Rsh300 is registered as the i-th element Rch_dt (i) of the array Rshcb_dt (step 1303).
The i-th element Lshcb (i) of the array Lshcb for expressing the traveling distance from the time when the sh300 is calculated until the time when the next Rsh300 is calculated is set to 0 (step 130).
3). Then, i is incremented by 1 for the next process, and the process ends.

After this, Rshcb_dt registered this time
Lshcb (i-1) corresponding to (i-1) is shown in FIG.
In step 803 of, until i is advanced by one,
It will be updated sequentially.

By the above processing, the array Rs is
A value proportional to each Rsh300 thus obtained is sequentially stored in hcb_dt. Further, in the array Lshcb, corresponding to each element of the array Rshcb_dt, the traveling distance from when the Rsh300 in which the element is proportional to when the next Rsh300 is obtained is sequentially accumulated.

Now, returning to FIG. 12, if it is determined in step 1201 that the flag is not 0, the Rs
Since h300 is a valid period, it is determined whether or not l, which represents the traveling distance after Rsh300 is calculated, exceeds 300 m (step 1206).
Updates the Rsh300 so as to represent the mileage up to the present after the calculation (step 1207), and ends the process.

On the other hand, if l exceeds 300 m, the value obtained by multiplying l, which represents the traveling distance after the correction variable Rsh300 is calculated, by the value of Ra + Rsh + Rshcb at that time, is added to Lcom at that time. The obtained value is set as a new Lcom (step 1208), and the distance errors d, l,
The flag is reset to 0 (step 1209), and Rs is set.
h1 is calculated from Rsh300. Rsh1 is Rsh3
The value obtained by multiplying 00 by a positive constant smaller than l is added to the stored Rsh0 (Rsh1 obtained last time) to obtain (step 1210). By this process, R
sh is changed from Rsh300 to Rsh1.

It should be noted that a value sufficiently larger than Rsh1 may be used as dRsh, and Rsh300 = dRsh for 300 m after Rsh300 is obtained.

Next, the La reset process in step 814 of FIG. 10 will be described.

FIG. 15 shows a processing procedure for this processing.

As shown in the figure, in this processing, is i = 0?
Imax (parallel data Lshcb up to the number of elements in dt)
For each i (steps 1501, 1505, 150
6), whether Lshcb (i) exceeds 2 km
Judge (step 1502), and only handle if exceeded
Rshcb The value of dt (i) is set to Rsh at that time.
The process of adding to cb (step 1503) is performed, and
After that, Rshcb Initialize dt (i) to 0.

Then, after that, i, Rsh, La, Lc
om is reset to 0 (step 1507), and the process ends.

By the processing of step 1507, when the current position (B) in the processing of FIG. 4 is estimated to be a position which is not continuous with the current position (B) where the vehicle estimated last time exists, or at an intersection or the like, approximately 90. If you make a turn, Ra last time
Lcom (Ra + R)
Each value of sh + Rshcb is a value obtained by weighting the travel distance for which the value was effective) and Rsh at that time point are initialized, and the travel distance 10 km is measured again from that time point using La. Become.

Further, from step 1501 to step 15
By processing up to 06, the array Rshcb Among the values proportional to each Rsh300 accumulated in dt, Rshcb reflecting the value of the one that has traveled for 2 km or more is obtained.

The processing that is started every 20 m running shown in FIG. 10 has been described above.

The process for obtaining the remaining correction variable Ra will be described below.

This processing is performed 10 times after the Ra was calculated last time.
When traveling for km or as the current position (B),
This is executed when the vehicle travels 10 km after the position which is not continuous with the current position (B) where the previously estimated vehicle exists is estimated or the vehicle makes a turn of about 90 degrees.

That is, it is executed when the variable La updated in step 803 of FIG. 10 exceeds 10 km.

FIG. 16 shows the procedure of this processing.

As shown in the figure, in this process, Ra is set to Rsh1, Rsh30 within 10 km as described above.
The value Lcom obtained by weighting the travel distance for which the value is valid is used for each value of R that sequentially changes by 0 and Rshcb, and is calculated by Ra = {(10km + Lcom) / 10km} -1 (step 1601).

When Ra is calculated, Rsh1 and Rs
h300, Rshcb, Lcom, La, Lsh, and i are initialized to 0 (step 1602), and the process ends.

The embodiment of the present invention has been described above.

As described above, according to the present embodiment, the distance coefficient is determined according to the difference between the traveling condition on the assumption that the vehicle is traveling at the estimated current position and the actual traveling condition represented by the sensor measurement value. Estimate the R error and correct it. Therefore,
No special equipment for correcting the distance coefficient R is required, and an appropriate correction can be performed regardless of the driving condition, and the correction can be performed even when driving on a road with few features such as intersections. It can be carried out. Therefore, it becomes possible to always calculate the traveling distance with better accuracy and obtain the current position of the vehicle with higher accuracy. In addition, as the current position (B), the current position (B) previously obtained
When a position that is not continuous with is obtained, or at an intersection, etc., approximately 9
Even when it is difficult to estimate the error of the distance coefficient R when the vehicle bends at 0 degrees, the error of the distance coefficient R estimated before that can be corrected to the extent of the reliability.
Can be reflected in.

[0125]

As described above, according to the present invention, the vehicle travels accurately regardless of the traveling speed of the vehicle and even when traveling on a road with few features without requiring special equipment. It is possible to provide a current position calculation device that can calculate the vehicle position with high accuracy by correcting the distance coefficient used to calculate the distance.

[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 distance performed in the 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.

FIG. 5 is a flowchart showing a procedure of current position display processing performed in an embodiment of the present invention.

FIG. 6 is a diagram showing a road expression format in map data used in an embodiment of the present invention.

FIG. 7 is a diagram showing a distance error d used in the present invention.

FIG. 8 is a diagram showing an example of a history of the current position displayed in the embodiment of the present invention.

FIG. 9 is a first flowchart showing a procedure of processing for correcting a distance coefficient performed in an embodiment of the present invention.

FIG. 10 is a second flowchart showing a procedure of processing for correcting the distance coefficient performed in the embodiment of the present invention.

FIG. 11 is a third flowchart showing a procedure of processing for correcting a distance coefficient performed in an embodiment of the present invention.

FIG. 12 is a fourth flowchart showing a procedure of processing for correcting the distance coefficient performed in the embodiment of the present invention.

FIG. 13 is a distance error d used in one embodiment of the present invention.
FIG. 7 is a diagram showing a positive / negative correspondence relationship between a correction variable Rch and a correction variable Rch.

FIG. 14 is a fifth flowchart showing a procedure of processing for correcting a distance coefficient performed in an embodiment of the present invention.

FIG. 15 is a sixth flowchart showing a procedure of processing for correcting the distance coefficient performed in the embodiment of the present invention.

FIG. 16 is a seventh flowchart showing a procedure of processing for correcting a distance coefficient performed 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 (3)

[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. A means for detecting, a means for detecting the rotational speed of the wheel, a traveling distance calculating means for sequentially calculating the traveling distance of the vehicle according to the detected rotational speed of the wheel and a set distance coefficient, successively detecting Means for estimating the road on which the vehicle exists and the position of the vehicle on the road according to the traveled distance of the vehicle, the detected traveling direction of the vehicle, and the road map represented by the map data; The amount of deviation between the traveling situation when the vehicle is traveling at a position where the vehicle exists on the road, and the traveling situation of the detected traveling direction or the traveling state of the vehicle represented by the detected traveling direction and the calculated traveling distance. According to The distance coefficient correcting means has a correction amount to be obtained and a distance coefficient correcting means for correcting the distance coefficient set in the travel distance calculating means, and the distance coefficient correcting means has a position where the previously estimated position of the vehicle is not continuous with a position of the vehicle. When it is estimated as the position to be changed, the distance coefficient set in the traveling distance calculation means is changed so that the correction amount of the correction applied to the distance coefficient until then is canceled, and the distance coefficient until then is changed. The present position calculation device is characterized in that the correction is performed according to the correction amount of each correction that has been effective for a predetermined degree or more in order to eliminate the deviation amount among the corrections performed on the present position. 2. A current position calculation device for calculating the current position of a vehicle, which is mounted on a vehicle that moves as wheels rotate, and means for storing map data representing a road map; A means for detecting, a means for detecting the rotational speed of the wheel, a traveling distance calculating means for sequentially calculating the traveling distance of the vehicle in accordance with the detected rotational speed of the wheel and a set distance coefficient, successively detecting Means for estimating the road on which the vehicle exists and the position of the vehicle on the road according to the traveled distance of the vehicle, the detected traveling direction of the vehicle, and the road map represented by the map data; The amount of deviation between the traveling situation when the vehicle is traveling at a position where the vehicle exists on the road, and the traveling situation of the detected traveling direction or the traveling state of the vehicle represented by the detected traveling direction and the calculated traveling distance. According to The distance coefficient correction means has a correction amount to be obtained and a distance coefficient correction means for correcting the distance coefficient set in the travel distance calculation means, and the distance coefficient correction means, when the vehicle turns right or left at a substantially right angle, the travel distance calculation means. The distance coefficient set to is changed so that the correction amount of the correction applied to the distance coefficient until then is canceled, and the deviation amount among the corrections applied to the distance coefficient up to that time is eliminated. Therefore, the present position calculation device is characterized in that the correction is performed according to the correction amount of each correction that is effective for a predetermined degree or more. 3. The current position calculation device according to claim 1, wherein the distance coefficient correction means calculates the deviation amount when the vehicle bends upward while traveling, and the calculated deviation amount is a predetermined value. When it is larger, the correction amount obtained according to the deviation amount,
Correct the distance coefficient set in the mileage calculation means,
Further, the correction that was effective for a predetermined amount or more to eliminate the deviation amount means that the deviation amount of a predetermined value or more occurs after the correction until the vehicle travels a predetermined distance. A current position calculation device, which is a correction not performed.