JP3672351B2 - Current position calculation device and distance coefficient correction method thereof - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a current position calculation device that is mounted on a moving body such as a vehicle, measures a travel distance, a travel direction, and the like and calculates a current position of the vehicle from these, and in particular, a travel distance measurement error. It is related with the technique which correct | amends.
[0002]
[Prior art]
Conventionally, the current position of a vehicle has been calculated based on the traveling direction of the vehicle measured by an orientation sensor such as a gyro and the traveling distance of the vehicle measured by a vehicle speed sensor or a distance sensor.
[0003]
Further, the travel distance of the vehicle is generally obtained by measuring the output shaft of the transmission or the rotation speed of the tire and multiplying the rotation speed by a distance coefficient that is the distance the vehicle travels per rotation of the tire. It is demanded by.
[0004]
In addition, in order to correct the error of the current position obtained from the traveling direction and the traveling distance of the vehicle in this way, as in the technique described in Japanese Examined Patent Publication No. 6-13972, it is required to be consistent with the road data. A so-called map matching technique for correcting the current position of the vehicle is known. According to this map matching technique, the accuracy of position calculation can be increased.
[0005]
By the way, during running, the tire diameter, that is, the distance coefficient changes every moment due to tire wear, expansion due to temperature change, and the like. For this reason, an error occurs in the calculation of the travel distance, and the current position cannot be calculated with high accuracy. For example, if an error of 1% exists in the travel distance coefficient per one rotation of the tire, an error of 1 km occurs when the vehicle travels 100 km.
[0006]
Such a travel distance measurement error can be corrected to some extent by the above-described map matching technique when traveling on a normal road. However, when driving 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, the error cannot be corrected sufficiently.
[0007]
Furthermore, once an error of about 1 km occurs between the measured current position and the true current position, it is difficult to correct the position correctly depending on the map matching technique.
[0008]
Therefore, in order to eliminate the measurement error of the travel distance, conventionally, it is obtained from (1) road data from the time when the intersection is turned (start point) to the next intersection (end point) and the measured number of revolutions. The distance coefficient per one rotation of the tire has been corrected by comparing the traveling distance. Also, as described in (2) JP-B-6-27652, a technique for correcting the above-described distance coefficient by comparing the distance on the map between the two beacons and the distance measured by running. Is also known. Further, (3) as described in Japanese Patent Laid-Open No. 2-107958, the vehicle speed is obtained using a GPS receiver that calculates a current position using a signal from a GPS satellite, and the detected tire rotation speed and A technique for correcting the above-described distance coefficient by comparing the above is also known.
[0009]
[Problems to be solved by the invention]
However, with the technique (1) described above, if the road between the intersections is slightly bent 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 in an intersection, the start and end points differ depending on which lane the vehicle turns through, but it is not easy to specify such lanes.
[0010]
In the technique (2) described above, there is a problem that accurate correction cannot be performed unless the road is straight, and a beacon facility that can be used by the vehicle must be provided.
[0011]
In the technique (3) described above, when the vehicle speed is low, accurate speed information may not be obtained, and when the vehicle speed change is large, the processing takes time and the calculation is performed. An error occurs in the speed. For this reason, there is a problem that accurate correction may not be performed. In addition, it is necessary to provide a GPS receiver and a GPS antenna that can be used in the vehicle. In addition, when the vehicle is in a traveling state where GPS signals cannot be received, such as under tunnels, overpasses, and shadows of buildings, there is also a problem that correction cannot be performed because GPS satellites cannot be used.
[0012]
Therefore, the present invention appropriately corrects the distance coefficient and obtains the vehicle position with high accuracy regardless of the number of intersections of the road on which the vehicle travels, the traveling speed of the vehicle, and without requiring special equipment. An object of the present invention is to provide a current position calculation device that can perform the above-described operation.
[0013]
Another object of the present invention is to provide a current position calculation device capable of avoiding inconveniences when a correction coefficient for correcting a distance coefficient is not reset for a long time.
[0014]
[Means for Solving the Problems]
To achieve the above object, the present invention is a current position calculation device that is mounted on a vehicle that moves with the rotation of a wheel and calculates the current position of the vehicle,
Means for storing map data representing a road map;
Traveling direction detection means for detecting the traveling direction of the vehicle;
Rotation speed detection means for detecting the rotation speed of the wheel;
A travel distance calculating means for calculating the travel distance of the vehicle according to the rotational speed of the wheel detected by the rotational speed detecting means and the set distance coefficient;
According to the travel distance of the vehicle calculated by the travel distance calculation means, the travel direction of the vehicle detected by the travel direction detection means, and the map data representing the road map, the road on which the vehicle exists and the road Means for estimating the location of the vehicle;
In a curved portion of the road, according to map data representing the travel distance, the traveling direction, and the road map, error calculation means for obtaining an error of the travel distance;
Distance coefficient correction means for generating a correction coefficient for correcting the distance coefficient based on the obtained error;
The distance coefficient correction means, when the correction coefficient is not reset based on a new output of the error calculation means after the correction coefficient is set and before traveling a predetermined distance, A current position calculation device is provided, characterized in that the absolute value of is reduced in a direction approaching zero.
[0015]
The present invention is also a method for correcting a distance coefficient for obtaining a travel distance of a vehicle based on a rotational speed of an axle in a current position calculation device that is mounted on a vehicle and calculates a current position of the vehicle,
In the curved part of the road, according to the map data representing the calculated travel distance of the vehicle, the detected traveling direction of the vehicle and the road map, the error of the travel distance is obtained,
Based on the obtained error, a correction coefficient for correcting the distance coefficient is generated,
By the correction coefficient, the distance coefficient is corrected sequentially while the vehicle is running,
If the correction coefficient is not reset based on a new travel distance error after the correction coefficient is set and before traveling a predetermined distance, the absolute value of the correction coefficient is set to a direction approaching zero. Provided is a distance coefficient correction method for a current position calculation device, characterized in that the distance is reduced.
[0016]
[Action]
In the present position calculation device of the present invention, the error of the travel distance is obtained by using the curved portion of the road, and the distance coefficient is corrected accordingly. Therefore, even if there is no feature such as an intersection on the running road In addition, the distance coefficient can be corrected without special equipment in the GPS or the like. Further, according to such a method of correcting the distance coefficient, there is no direct dependence on the traveling speed of the vehicle.
[0017]
In addition, if the correction coefficient is not reset based on a new travel distance error after the correction coefficient is set and before traveling a predetermined distance, the absolute value of the correction coefficient approaches 0. Reduced to This is because when the correction coefficient is not updated over a long distance, that is, when a straight road is long and error data of a new traveling distance is not acquired over a long distance, the current correction coefficient may be maintained as it is. On the other hand, the situation that the mileage error may increase may be considered. According to the present invention, such inconvenience can be avoided.
[0018]
【Example】
Hereinafter, an embodiment of a current position calculation apparatus according to the present invention will be described.
[0019]
First, the configuration of the current position calculation apparatus according to the present embodiment will be described with reference to FIG.
[0020]
The present position calculation apparatus according to the present embodiment includes an angular velocity sensor 201 that detects a change in traveling azimuth by detecting a yaw rate of the vehicle, an azimuth sensor 202 that detects a traveling azimuth of the vehicle by detecting geomagnetism, A vehicle speed sensor 203 that outputs pulses at time intervals proportional to the rotational speed of the output shaft of the transmission is provided.
[0021]
Further, a display 207 that displays a map around the current position, a mark indicating the current position, and the like, a switch 204 that receives a command to switch the scale of the map displayed on the display 207 from the driver, and stores digital map data A CD-ROM 205 and a driver 206 for reading map data from the CD-ROM 205. Further, a controller 208 that controls the operation of each peripheral device described above is provided.
[0022]
Next, the controller 208 includes an A / D converter 209 that converts the signal (analog) of the angular velocity sensor 201 into a digital signal, and an A / D converter 210 that converts the signal (analog) of the azimuth sensor 202 into a digital signal. The counter 216 that counts the number of pulses output from the vehicle speed sensor 203 every 0.1 second, the parallel I / O 211 that inputs whether or not the switch 204 is pressed, and the map data read from the CD-ROM 205 are transferred. A direct memory access (DMA) controller 212 and a display processor 213 for displaying a map image on the display 207.
[0023]
The controller 208 further includes a microprocessor 214 and a memory 215. The microprocessor 214 outputs signals from the angular velocity sensor 201 obtained through the A / D converter 209, signals from the direction sensor 202 obtained through the A / D converter 210, and output pulses from the vehicle speed sensor 203 counted by the counter 216. Number, whether or not the switch 204 is input via the parallel I / O 211, the map data from the CD-ROM 205 obtained via the DMA controller 212 is received, processing is performed based on these signals, and the current position of the vehicle Is calculated and displayed on the display 207 via the display processor 213. As shown in FIG. 2, the vehicle position is displayed by superimposing an arrow mark or the like on a map already displayed on the display 207. Thereby, the user can know the current position of the vehicle on the map. The memory 215 is used as a work area when the microprocessor 214 performs processing, and a ROM that stores a program that defines the contents of processing (to be described later) for realizing such operations, various tables to be described later, and the like. RAM.
[0024]
Hereinafter, the operation of the current position calculation apparatus according to the present embodiment will be described.
[0025]
First, three processes will be described: a process for calculating the traveling direction and 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.
[0026]
FIG. 3 illustrates a flow of processing for calculating the traveling direction and traveling distance of the vehicle.
[0027]
This process is a routine of the microprocessor 214 that is activated and executed at a constant cycle, for example, every 100 ms.
[0028]
In this routine, first, the output value of the angular velocity sensor 201 is read from the A / D converter 209 (step 401). The angular velocity sensor 201 can detect only a relative value in the traveling direction of the vehicle because a change in direction is output as the output value. Therefore, next, the output value of the azimuth sensor 202 is read from the A / D converter 210 (step 402), and the absolute azimuth calculated based on the output value of the azimuth sensor 202 and the azimuth change output from the angular velocity sensor 201 ( The estimated azimuth of the vehicle is determined using (angular velocity output) (step 403).
[0029]
For example, when the vehicle speed is low for a long time, the angular velocity sensor has a large error. Therefore, when the vehicle speed is low for a certain time or more, the direction is determined by using only the direction sensor direction.
[0030]
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 a distance coefficient R, a distance advanced in 0.1 seconds is obtained (step 405). A method for obtaining the distance coefficient R will be described later.
[0031]
Next, the travel distance value per 0.1 second thus determined is added to the previously obtained value to check whether the travel distance of the vehicle has reached 20 m (step 406). If not (No in step 406), the current process is terminated and a new process is started.
[0032]
As a result of the traveling distance calculation process, when the accumulated traveling distance becomes a certain distance, for example, 20 m (Yes in Step 406), the traveling direction and the traveling distance (20 m) at that time are output (Step 407). In step 407, the accumulated distance is further initialized, and the accumulated travel distance is newly started.
[0033]
Next, processing for obtaining the current position of the vehicle based on the calculated traveling direction and traveling distance will be described.
[0034]
FIG. 4 shows the flow of this process.
[0035]
This process is a routine of the microprocessor 214 that is activated and executed in response to the output of the travel direction and travel distance from FIG. That is, this process is started every time the vehicle travels 20 meters.
[0036]
In this process, first, the travel direction and travel distance output in step 407 are read (step 501). Next, based on these values, the movement amount of the vehicle is obtained separately in the latitude and longitude directions. Further, the movement amount in each direction is added to the current position (B) of the vehicle obtained in the previous process to obtain the current position (A) (step 502).
[0037]
If there is no previously obtained position, such as immediately after the start of the device, the current position (A) is obtained using the separately set position as the previously obtained position.
[0038]
Next, a map around the obtained current position (A) is read from the CD-ROM 205 via the driver 206 and the DMA controller 213, and within a preset distance D centered on the current position (A). Some road data (line segment) is extracted (step 503).
[0039]
As the road data, for example, as shown in FIG. 6, a plurality of line segments 81 to 85 that connect two points are approximated, and those line segments are expressed by the coordinates of the start point and the end point. be able to. For example, the line segment 83 is expressed by its start point (x3, y3) and end point (x4, y4).
[0040]
Next, from the line segments extracted in step 503, only those line segments whose azimuth is within the predetermined traveling direction and predetermined value are extracted (step 504). Further, a perpendicular is drawn from the current position (A) for all the extracted line segments, and the length of the perpendicular is obtained (step 505).
[0041]
Next, the error cost value defined below is calculated for all the line segments extracted in step 504 using the lengths of the perpendicular lines.
[0042]
Error cost = α × | Advance direction−Line segment direction | + β × | Length of perpendicular |
Here, α and β are weighting factors. The values of these coefficients may be changed depending on whether the shift in the traveling direction and the direction of the road or the shift in the distance between the current position and the road is important when selecting the road where the current position exists. For example, when importance is attached to a road whose direction is close to the traveling direction, α is increased.
[0043]
When the error cost of each line segment is calculated, the line segment with the smallest error cost value is selected from the line segments for which the error cost has been calculated (step 506), and the line segment and the perpendicular line are selected. The intersecting point (the bottom of the vertical line) is set as the corrected current position (B) (step 507).
[0044]
In step 503 described above, road data (line segment) within a preset distance D centered on the current position (A) is extracted. This distance D was selected in the previous step 506. It may be a value determined based on the value of the road error cost.
[0045]
Here, the reason for obtaining the search range based on the error cost is that if the error cost is large, the reliability of the accuracy of the current position (B) obtained last time is considered to be low. This is because searching for a road is more appropriate for finding the correct current position.
[0046]
Next, processing for displaying the obtained vehicle position and direction will be described.
[0047]
FIG. 5 shows the flow of this process.
[0048]
This process is a routine of the microprocessor 214 that is activated and executed every second.
[0049]
First, it is determined by checking the contents of the parallel I / O 211 whether the switch 204 is instructed to change the scale of the map (step 601). If it has been pressed (Yes in step 601), a predetermined scale flag is set correspondingly (step 602).
[0050]
Next, the current position (B) obtained in the process of FIG. 4 is read (step 603), and a map of a scale corresponding to the contents of the scale flag switched in step 602 is displayed on the display 207, for example, FIG. The screen is displayed in such a state (step 604).
[0051]
Then, the current position (B) of the vehicle and the traveling direction of the vehicle are displayed using, for example, the arrow symbol “↑” as shown in FIG. 2 (step 605). Finally, a north mark indicating north and a distance mark corresponding to the scale are displayed as shown in FIG. 2 so as to be superimposed on these (step 606).
[0052]
In the present embodiment, the vehicle position and direction are indicated by using the arrow symbols as described above. However, in the display form of the vehicle position and direction, the display state is clearly shown for the position and the traveling direction. If it exists, the form may be arbitrary. The same applies to the north mark and the like.
[0053]
As described above, the travel distance of the vehicle is obtained by multiplying the number of pulses output from 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, if the distance coefficient R is set to a fixed value, the distance cannot be obtained accurately as the vehicle travels. Therefore, in this embodiment, the current position (B) (step 508) obtained by the processing of FIG. 4 sequentially, the road direction obtained from the map data read from the CD-ROM 205 via the driver 206, By comparing the vehicle direction (step 403) obtained by the processing, it is determined whether the current position (B) is advanced or delayed with respect to the actual position, and the distance coefficient R is dynamically corrected. .
[0054]
Such correction of the distance coefficient R can be performed as follows, for example. That is, a correction coefficient Rsh for dynamically correcting the distance coefficient R sequentially is introduced. The distance coefficient R is dynamically corrected according to the distance coefficient R = R0 × (1 + Rsh). Here, R0 indicates an initial value of a predetermined distance coefficient R. The correction coefficient Rsh is used to detect an error in the travel distance successively generated during travel using a road curve (curved portion) or the like, and to finely correct the distance coefficient R based on this.
[0055]
The microprocessor 214 sequentially changes the correction coefficient Rsh by processing to be described later. Hereinafter, a specific procedure of the processing of this embodiment will be described.
[0056]
First, when the present apparatus is activated, various variables and flags used in the processing described below in the initialization processing, that is, the distance error amount d, the distance correction coefficient Rsh, the distance correction execution distance l, and the distance correction effective distance Lsh. The distance correction execution flag flag is initialized to 0.
[0057]
The processing shown in FIG. 8 is a routine of the microprocessor 214 that is activated and executed in response to the output of the current position (B) by the processing of FIG. That is, this process is started every time the vehicle travels 20 meters. In this process, the various sensor data and map data previously read in the process of FIG. 4 are used. Of course, reading may be performed again at this point.
[0058]
In FIG. 8, first, it is checked whether or not the distance correction execution flag flag is 0 (step 801). If it is not 0, the process jumps to step 804, and if it is 0, the distance error amount d is calculated (step 802). As will be understood later, this flag is “1” until the vehicle travels 300 m after calculating Rsh. The distance error amount d is an amount corresponding to a travel distance error caused by a deviation from an appropriate value of the distance constant R, and this calculation method will be described later. Next, the distance Lsh is updated (step 803). The distance Lsh is reset in step 906 of FIG. 10 to be described later and indicates the travel distance after Rsh calculation 2. In the next step 806, it is checked whether or not the distance has reached 2 km or more.
[0059]
In step 804, the distance error amount d is checked. If d is 0, the process jumps to step 806, and if it is not 0, Rsh calculation 1 described later with reference to FIG. 11 is performed (step 805).
[0060]
In step 806, it is checked whether or not the distance Lsh updated in step 803 is 2 km or more. If the distance Lsh is less than 2 km, this process ends. If it is 2 km or more, the correction coefficient Rsh is reduced (step 807). This reduction process is to reduce the value of the correction coefficient Rsh in a direction approaching 0, and a specific method thereof will be described later. The reason for performing the reduction process is as follows. That is, for example, when a straight road continues over a long distance such as an expressway, the distance error amount d in step 802 may not be calculated over a long period (d = 0). In this embodiment, Rsh is considered to be reliable only after being updated in the short term. If there is no opportunity to update the correction coefficient Rsh once calculated, the Rsh has a correct value in a certain period. If so, it is not necessarily correct in the following period. Therefore, if such a value of Rsh is continuously used for a long period of time, the error in the travel distance may be increased. This reduction process is performed in order to avoid such a situation. Finally, in step 808, the distance Lsh is reset to 0, and this process ends.
[0061]
Next, a specific method for calculating the distance error amount d will be described.
[0062]
In the present embodiment, the distance error amount d is determined according to the actual way of turning of the vehicle at the location of the road curve.
[0063]
For example, it is assumed that the current position (B) output at step 508 in FIG. 4 travels on the road A in FIG. On the other hand, for example, the current position of the vehicle obtained from the traveling distance of the traveling azimuth of the vehicle with reference to point a of the current position (B) that is sequentially output a predetermined distance before the starting point o on the traveling curve. A trajectory (a trajectory obtained by accumulating successive azimuths and movement amounts without applying map matching after the point a) is a trajectory that starts to bend from a point that exceeds the point o as indicated by a broken line in the figure. Suppose there was.
[0064]
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 using the distance coefficient R that the vehicle has reached the curve o, the vehicle has not started to turn, so it is considered that the vehicle has not actually reached the curve. Further, the degree that the distance coefficient R is larger than the true value can be estimated from the distance d in the figure that represents the distance between the point where the vehicle actually starts to bend and the curve start point o.
[0065]
Conversely, when the trajectory of the current position of the vehicle obtained from the travel distance in the traveling direction of the vehicle is a trajectory that starts to bend before reaching the point o, the distance coefficient R is smaller than the true value. It can be estimated. This is because the vehicle starts to bend before it is estimated using the distance coefficient R that the vehicle has reached the curve o, so that it is actually considered that the vehicle has already reached the curve o. Also in this case, the degree that the distance coefficient R is smaller than the true value can be estimated from the distance d in the drawing that represents the distance between the point where the vehicle actually starts to bend and the curve o.
[0066]
Therefore, the deviation from the true value of the distance coefficient and its degree can be determined based on d in the figure, and the correction coefficient Rsh can be determined so as to cancel it. A method for setting Rsh will be described later.
[0067]
As another method of obtaining the distance error amount d, whether the vehicle has started to bend before the vehicle is estimated from the difference between the vehicle direction and the road using the distance coefficient R that the vehicle has reached the curve o, or the vehicle is curved. It is determined whether or not the vehicle has begun to turn after the time estimated using the distance coefficient R to reach o, and the distance coefficient R is true based on the curve bending direction and the integrated value of the vehicle heading and the road heading difference. The degree of deviation from the value of can also be obtained.
[0068]
According to FIG. Step 805 An example of a specific procedure of the Rsh calculation process is shown.
[0069]
First, it is checked whether or not flag is 0 (step 901). If 0, the process proceeds to the route (steps 902 and 903) for calculating the correction coefficient Rsh based on the distance error amount d. If not 0, the process proceeds to step 904.
[0070]
In step 902, calculation 1 of the correction coefficient Rsh based on the distance error amount d is performed. In this embodiment, when Rsh is calculated in step 902, the absolute value is set to a value that is larger than a value that seems to be appropriate. The reason why the value of Rsh is intentionally set to an excessive value in this way is as follows. That is, when the distance error d is confirmed, the current position deviation is already accumulated, and the current position deviation is stored as it is simply by correcting Rsh to an appropriate value. In the present embodiment, the correction coefficient Rsh (absolute value) is set to be larger than an appropriate value for a predetermined distance (300 m in the present embodiment) after the correction of Lsh, so that the distance coefficient R is greater than its true value. A value that seems to be correct for the distance coefficient R by deliberately shifting and correcting the deviation of the current position (B) accumulated so far while gradually moving this 300 m, and then reducing the correction coefficient Rsh. Set to. Thus, by correcting the shift of the current position little by little over 300 m, it is possible to smoothly move without maintaining the display position of the current position while shifting or jumping to a new position. The specific sign and size of Rsh will be described later with reference to FIG.
[0071]
Next, in step 903, flag is set to 1 and this process is terminated.
[0072]
If the flag is not 0 in the previous step 901 (that is, if the flag is 1), it is checked in step 904 whether the distance l, which is the travel distance after setting the flag to 1, is 300 m or less. If it is 300 m or less, the distance l is updated in step 905 and this process is terminated.
[0073]
When the distance l exceeds 300 m in step 904, the various variables d, Lsh, l, and flag are all reset to 0 (step 906). Thereafter, Rsh calculation 2 is performed (step 907). As described above, this processing corresponds to the operation of resetting the excessive Rsh calculated in step 902 to a value that seems to be appropriate. A specific method of calculating Rsh in this step will be described later with reference to FIG.
[0074]
In the process of FIG. 10, after the change of Rsh based on the distance error amount d, the flag remains 1 while the distance l is 300 m or less, and steps 802 and 803 are bypassed in the process of FIG. 8 as described above. I try to do it. This is to prevent the operation of obtaining a new Rsh while the vehicle is traveling with the distance coefficient R deliberately deviating from a value that seems appropriate.
[0075]
As shown in FIG. 11, the sign of Rsh change amount Rsh300 in Rsh calculation 1 is negative if d is positive, and positive if d is negative. As a result, the distance coefficient R can be corrected in the direction of an appropriate value as described above. However, as shown in FIG. 9, the value of d is positive when the road curve goes around (overshoot), and when the road curve goes inside (under) Negative) Rsh300 Is a value obtained by multiplying the absolute value of d by a positive constant k. The value of k is intentionally set to an excessively large value so that the corrected distance coefficient R passes a value that seems to be an appropriate value. However, an extremely large value is determined to be due to a malfunction, and an upper limit and a lower limit are set for the value of Rsh300. Then, Rsh is obtained by Rsh = Rsh0 + Rsh300. However, when a value sufficiently larger than the value that Rsh0 can take is used as Rsh300, Rsh = Rsh300 may be set. Rsh0 is Rsh before the occurrence of the distance error amount.
[0076]
In addition, Rsh300 mentioned above In addition to the method of determining the size of, a method using a table in which predetermined numerical values are stored in advance according to the size category of d may be employed.
[0077]
A specific example of the sign and size when the correction coefficient Rsh is reduced after reaching 300 m will be described with reference to FIG. The sign of the amount of change in Rsh is positive if the sign of Rsh300 is positive and negative if it is negative. Also, the size is
| Rsh | = m × | Rsh300 | + Rsh0
And Here, m is a positive constant smaller than 1.
[0078]
Finally, the Rsh reduction process shown in step 807 of FIG. 8 will be described.
[0079]
As described above, this reduction processing is performed to reduce the value of the correction coefficient Rsh in a direction closer to 0, and is executed as follows.
[0080]
(1) When Rsh> 0,
Rsh = Rsh−n
Here, n is an arbitrary positive constant. When the calculated Rsh becomes negative, Rsh = 0 is set.
[0081]
(2) When Rsh <0,
Rsh = Rsh + n
Here, n is an arbitrary positive constant the same as (1). When the calculated Rsh becomes positive, Rsh = 0 is set.
[0082]
As described above, with this reduction process, when a straight road continues for a long distance such as an expressway, there is no opportunity to update the correction coefficient Rsh once calculated, and it is used for a long time. You can avoid the situation that continues.
[0083]
Although only one embodiment of the present invention has been described above, various modifications and changes can be made. For example, numerical values (100 ms, 1 s, 20 m, 300 m, 2 km) of various times and distances in the above description are not strictly limited to these values.
[0084]
【The invention's effect】
As described above, according to the present invention, the distance coefficient is appropriately corrected regardless of the number of intersections of the road on which the vehicle travels, the traveling speed of the vehicle, and without requiring special equipment. It is possible to provide a current position calculation device that can determine the vehicle position. In addition, it is possible to avoid the inconvenience when the correction coefficient for correcting the distance coefficient is not reset for a long time.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a current position calculation apparatus 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 one embodiment of the present invention.
FIG. 3 is a flowchart showing a procedure for calculating a traveling direction and a distance performed in an embodiment of the present invention.
FIG. 4 is a flowchart showing a procedure of a current position calculation process performed in an embodiment of the present invention.
FIG. 5 is a flowchart showing a procedure of a current position display process 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 flowchart showing an initialization process performed in an embodiment of the present invention.
FIG. 8 is a flowchart showing a procedure of correction coefficient calculation processing performed in an embodiment of the present invention.
9 is a diagram for explaining a calculation process of a distance error amount d shown in FIG.
10 is a flowchart showing a procedure of Rsh calculation processing shown in FIG.
FIG. 11 is a diagram showing the processing contents of Rsh calculation 1 shown in FIG. 10;
12 is a diagram showing the processing content of Rsh calculation 2 shown in FIG. 10; FIG.
[Explanation of symbols]
201 Angular velocity sensor
202 Direction sensor
203 Vehicle speed sensor
204 switches
205 CD-ROM
206 CD-ROM driver
207 display
208 controller

Claims (5)

A current position calculating device for calculating a current position of the vehicles,
Means for storing map data representing a road map;
Traveling direction detection means for detecting the traveling direction of the vehicle ;
A travel distance calculating means for calculating a travel distance of the vehicle using the number of pulses acquired from a vehicle speed sensor mounted on the vehicle and a set distance coefficient;
Using the travel distance of the vehicle calculated by the travel distance calculation means, the travel direction of the vehicle detected by the travel direction detection means, and map data representing the road map, the road on which the vehicle exists and the road Means for estimating the location of the vehicle;
In the curved portion of the road, an error calculating means for calculating an error of the traveling distance using the travel distance, before Symbol progressive lateral position, and map data representing the road map,
Generating a correction coefficient for correcting the pre-Symbol distance coefficients using the calculated error, and a distance factor correcting means for correcting the distance factor using a correction coefficient thus generated,
The distance coefficient correction means includes
When said pre-Symbol error calculation means during the period from to generate the correction factor until traveling a predetermined first distance does not calculate a new error, the absolute value of the correction coefficient used in the correction of the distance factor Is reduced in a direction approaching zero. A current position calculation apparatus according to claim 1,
The error calculating means obtains a curve of a road on which an estimated vehicle exists based on map information represented by the map data, compares this with a traveling direction of the vehicle, and an estimated vehicle position of the calculated road or bent at or slower bent vehicle at an earlier time than the lead to bend determined based on the comparison result, to calculate the error of the traveling distance on the basis of the degree of fast or slow
A current position calculation device characterized by the above . A current position calculation apparatus according to claim 2,
The distance factor correcting means in accordance with the degree of the fast or slow, pre Kiho with determining the absolute value of the positive coefficient greater than the distance coefficient when the vehicle is bent at the early time points It is corrected to, and, as in the case where the vehicle is bent at the later point in time is for correcting said distance factor to a smaller value, the current position calculating system and determines the sign of the previous Kiho positive coefficient. The current position calculation device according to claim 1, 2, or 3,
The distance factor correcting means, before Kiho set larger than the value that would the absolute value proper during positive coefficient setting, when the vehicle travels a predetermined second distance after the setting, those 該補 positive A current position calculating apparatus, wherein a coefficient setting value is changed to a value that is considered appropriate.   A method of correcting a distance coefficient used for calculating a travel distance of a vehicle, performed by a current position calculation device that calculates a current position of the vehicle,
  The current position calculation device includes:
  Detecting the traveling direction of the vehicle;
  Calculating the mileage of the vehicle using the number of pulses acquired from a vehicle speed sensor mounted on the vehicle and a set distance coefficient;
  Estimating the road where the vehicle exists and the position where the vehicle exists on the road using map data representing the calculated travel distance of the vehicle, the detected traveling direction of the vehicle, and a road map;
  Calculating an error of the travel distance using map data representing the travel distance, the traveling direction, and the road map in a curved portion of a road;
  Generating a correction coefficient for correcting the distance coefficient using the calculated error, and correcting the distance coefficient using the generated correction coefficient;
  The step of correcting the distance coefficient includes:
  When the error of the travel distance is not calculated between the generation of the correction coefficient and the travel of a predetermined distance, the absolute value of the correction coefficient used for the correction of the distance coefficient is reduced toward 0.
A method of correcting a distance coefficient characterized by

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