JP3764507B2 - Current position calculation device - 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 traveling 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 corrects.
[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 travel distance of the vehicle measured by a vehicle speed sensor or a distance sensor.
[0003]
The vehicle travel distance is generally measured by measuring the output shaft of the transmission or the rotation speed of the tire, and multiplying the rotation speed by the distance coefficient that is the distance the vehicle travels per rotation of the tire. It is demanded by.
[0004]
Further, in order to correct the error of the current position obtained from the traveling direction and the travel distance of the vehicle in this way, the vehicle that is obtained so as to be consistent with the road data as in the technique described in Japanese Patent Publication No. 6-13972. A so-called map matching technique for correcting the current position of the image 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 there is an error of 1% 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 measurement error of the travel distance 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 rotation speed. The distance coefficient per one rotation of the tire has been corrected by comparing with the travel 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 accurately corrects the distance coefficient and obtains the vehicle position with high accuracy regardless of the characteristics of the road on which the vehicle travels and 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 capable of
[0013]
[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;
Means for detecting the traveling direction of the vehicle;
Means for detecting the rotational speed of the wheel;
Sequentially, travel distance calculation means for calculating the travel distance of the vehicle according to the detected wheel rotation speed and the set distance coefficient,
Means for estimating a road where the vehicle exists and a position where the vehicle exists on the road according to the road map represented by the travel distance of the detected vehicle, the detected traveling direction of the vehicle, and the map data,
The driving situation when the vehicle is traveling on the estimated position of the vehicle on the road, and the detected traveling direction or the traveling state of the vehicle represented by the detected traveling direction and the calculated traveling distance A correction amount determined according to the amount of deviation, and a distance coefficient correction means for correcting the distance coefficient set in the travel distance calculation means.
The distance coefficient correcting means is the travel distance calculating means when a position that is not continuous with the previously estimated position of the vehicle is estimated as a position where the vehicle exists, or when the vehicle turns right and left substantially at a right angle. Is changed so that the correction amount of the correction applied to the distance coefficient is cancelled, and the deviation amount among the corrections applied to the distance coefficient is canceled. Therefore, there is provided a current position calculating apparatus characterized by correcting an amount obtained according to a correction amount of each correction that is effective for a predetermined degree or more.
[0014]
[Action]
In the present position calculation device according to the present invention, the traveling state when the vehicle is traveling on the estimated position on the road and the detected traveling direction or the detected traveling direction and the calculated position are calculated. The correction amount obtained in accordance with the amount of deviation from the traveling state of the vehicle represented by the traveling distance, and the distance coefficient set in the traveling distance calculation means are corrected.
[0015]
Further, when a position that is not continuous with the position where the vehicle exists is estimated as the position where the vehicle exists, or when the vehicle turns right and left substantially vertically, the distance set in the travel distance calculation means The coefficient is changed so that the correction amount of the correction applied to the distance coefficient so far is canceled, and a predetermined degree to eliminate the deviation amount among the corrections applied to the distance coefficient until then The amount obtained according to the correction amount of each correction that has been effective as described above is corrected.
[0016]
【Example】
Hereinafter, an embodiment of a current position calculation apparatus according to the present invention will be described.
[0017]
FIG. 1 illustrates the configuration of the current position calculation apparatus according to the present embodiment.
[0018]
That is, the current position calculation device according to the present embodiment includes an angular velocity sensor 201 that detects a change in traveling azimuth by detecting the yaw rate of the vehicle, and an azimuth such as a geomagnetic sensor that detects the traveling azimuth of the vehicle by detecting geomagnetism. A sensor 202 and a vehicle speed sensor 203 that outputs pulses at time intervals proportional to the rotational speed of the output shaft of the vehicle transmission are provided.
[0019]
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.
[0020]
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.
[0021]
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, and processing based on these signals is performed. The current position is calculated and displayed on the display 207 via the display processor 213. The vehicle position is displayed by superimposing an arrow mark or the like on the map already displayed on the display 207, as shown in FIG. Thereby, the user can know the current position of the vehicle on the map. The memory 215 includes a program that defines the contents of processing (to be described later) for realizing such operations, a ROM that stores various tables to be described later, and a work area when the microprocessor 214 performs processing. RAM to be used.
[0022]
Hereinafter, the operation of the current position calculation apparatus according to the present embodiment will be described.
[0023]
First, three processes will be described: a process for calculating the traveling direction and travel 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.
[0024]
FIG. 3 illustrates the flow of processing for calculating the traveling direction and travel distance of the vehicle.
[0025]
This process is a routine of the microprocessor 214 that is activated and executed at a constant cycle, for example, every 100 ms.
[0026]
In this routine, first, the output value of the angular velocity sensor 201 is read from the A / D converter 209 (step 401). Since a change in direction is output as the output value of the angular velocity sensor 201, only a relative value in the traveling direction of the vehicle can be detected. 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).
[0027]
For example, when the vehicle speed is low for a long time, the angular velocity sensor 201 has a large error. Therefore, when the vehicle speed is low for a certain time or more, only the direction output by the direction sensor 202 is used. .
[0028]
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.
[0029]
Next, the travel distance value per 0.1 second obtained in this way 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.
[0030]
As a result of the travel distance calculation process, when the accumulated travel distance becomes a certain distance, for example, 20 m (Yes in Step 406), the traveling direction and the travel distance (20 m) at that time are output (Step 407). In step 407, the accumulated distance is further initialized, and accumulation of the travel distance is newly started.
[0031]
Next, processing for obtaining the current position of the vehicle based on the calculated traveling direction and travel distance will be described.
[0032]
FIG. 4 shows the flow of this process.
[0033]
This processing is a routine of the microprocessor 214 that is activated and executed in response to the output of the traveling direction and travel distance from FIG. That is, this process is started every time the vehicle travels 20 meters.
[0034]
In this process, first, the traveling direction and the 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 of the vehicle obtained in the previous process to obtain the current position (A) (step 502).
[0035]
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.
[0036]
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).
[0037]
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).
[0038]
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). In addition, a point where each line segment intersects with a perpendicular line (line segment perpendicular) is a candidate point.
Next, error cost values defined below are calculated for all candidate points obtained in step 504 using the lengths of the perpendicular lines.
[0039]
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 current position is important in selecting the road on which the current position or the road is shifted, or the current position or the road is shifted. For example, when importance is attached to a road whose direction is close to the traveling direction, α is increased.
[0040]
If the error cost of each line segment is calculated, the candidate point with the smallest error cost value is selected from the line segments for which the error cost has been calculated (step 506), and the selected candidate point is corrected. The current position (B) is set (step 507).
[0041]
Incidentally, 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.
[0042]
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.
[0043]
The method for obtaining the current position (B) may be as follows.
[0044]
That is, first, candidate points are obtained from a certain position as described above. Then, the current position (B) is obtained from among 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, the candidate point for each is obtained, and 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, the current position (A) for each is obtained, candidate points are obtained from each obtained current position (A), and all the obtained candidate points are obtained. The process for obtaining the current position (B) is repeated. Therefore, in this case, each next candidate point is obtained based on a candidate point different from the candidate point selected as the previous current position (B). Further, the next current position (B) may be obtained based on a candidate point different from the candidate point selected as the previous current position (B).
[0045]
Next, processing for displaying the obtained vehicle position and direction will be described.
[0046]
FIG. 5 shows the flow of this process.
[0047]
This process is a routine of the microprocessor 214 that is activated and executed every second.
[0048]
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).
[0049]
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).
[0050]
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).
[0051]
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.
[0052]
Next, how to obtain the distance coefficient R used for calculating the distance in the processing step 405 of FIG. 3 will be described.
[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, and FIG. 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.
[0055]
  That is, three correction variables Rsh, Ra, and Rshcb are introduced. Then, the distance coefficient R is dynamically corrected according to the distance coefficient R = R0 × (1 + Ra + Rsh + Rshcb). Here, R0 indicates an initial value of a predetermined distance coefficient R. Also, Rsh is shortTo correct the distance coefficient R periodicallyThe The correction variable Ra isThis is for correcting the distance coefficient R in the long term according to Rsh obtained while traveling 10 km. Rshcb is used to correct R by the amount corresponding to the probability of Rsh obtained when it is determined that Rsh obtained so far is not suitable for use as it is to obtain Ra. It is.
[0056]
Now, these correction variables Rsh, Rshcb, Ra are sequentially changed by the microprocessor 214 executing the following processing.
[0057]
In the following, first, the contents of this process will be described individually, and then how the correction variable Rshcb, the correction variable Rsh, and the correction variable Ra are changed by these processes during actual vehicle travel. Will be explained.
[0058]
First, an outline of how to obtain the correction variable Rsh will be described.
[0059]
The correction variable Rsh is determined in accordance with the actual way of turning of the vehicle at the location of the road curve.
[0060]
For example, it is assumed that the current position (B) output in 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. Assume that the trajectory is a trajectory that starts to bend from a point that exceeds the point o as indicated by a broken line in the figure.
[0061]
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 the vehicle has 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 bend. 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.
[0062]
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 intersection 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 error d in the drawing that represents the distance between the point where the vehicle actually starts to turn and the curve o.
[0063]
Accordingly, it is possible to determine the direction and degree of deviation of the distance coefficient from the true value from d in the figure, and to determine the correction variable Rsh so as to cancel it.
[0064]
Alternatively, from the difference between the direction of the vehicle and the road, the vehicle starts to turn before it is estimated using the distance coefficient R that the vehicle has reached the curve o, or the distance coefficient R is calculated if the vehicle has reached the curve o. You may make it determine whether the vehicle started to bend after the time estimated using it. In this case, the degree by which the distance coefficient R deviates from the true value can be determined from the integrated value of the difference between the vehicle direction and the road direction.
[0065]
In the present embodiment, when the distance error d is detected in this way, the correction variable Rsh is obtained according to the value of the distance error d, and the distance coefficient R is corrected.
[0066]
Further, the correction of the distance coefficient R by the correction variable Rsh is performed as follows.
[0067]
That is, first, while traveling 300 m, by making the absolute value of Rsh larger than the value for obtaining the correct R, a correct value is gradually obtained as the current position (B) while traveling 300 m. This is presumed that when the distance error d is obtained, the erroneous current position (B) is obtained due to the error of the distance coefficient so far. However, here, if the current position (B) is corrected to a correct position at a time, the display mark of the current position described above moves in the direction opposite to the traveling direction or moves to a position away from the driver at once. Will be confusing. Therefore, while traveling 300 m, the absolute value of Rsh is made larger than the value for obtaining the correct R, and while traveling 300 m, the mark display position of the current position (B) is gradually corrected to the correct position. To go.
[0068]
Then, after traveling 300 m, Rsh is corrected again to a value for obtaining the correct Rsh, and thereafter the current position (B) is obtained with the correct distance coefficient R. Furthermore, in this embodiment, when the obtained Rsh is valid for 2 km or more (when no new Rsh is obtained), this Rsh is gradually decreased. The case where the vehicle is effective for 2 km or more is because 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 decreased so that the influence thereof is reduced.
[0069]
In the following, in order to facilitate understanding of the explanation, Rsh used while traveling 300 m is represented as Rsh300, and Rsh obtained thereafter is represented as Rsh1.
[0070]
  Next, the correction variable Ra is a correction variable for correcting the distance coefficient R in accordance with Rsh1 and Rsh300 obtained during 10 km every time the vehicle travels 10 km. Correction variableRaIs a value Lcom obtained by weighting the mileage for which the value was effective to each value of Ra + Rsh + Rshcb that sequentially changes during 10 km,
Ra = {(10 km + Lcom) / 10 km} −1.
[0071]
When Ra is obtained, Rsh1 or Rsh300 and Rshcb that have been valid up to that point are initialized to zero.
[0072]
Thus, Ra is used to correct the distance coefficient R to a value obtained by approximately averaging the values of each R used during the 10 km every 10 km. However, the current position (B) in the process of FIG. 4 is a position that is not continuous with the position where the previously estimated vehicle exists, such as a position on a road different from the road where the current position (B) has existed so far. Can be estimated that Rsh1 and Rsh300 obtained so far are not correct. This is because there is a possibility that Rsh1 or Rsh300 may be obtained from the distance error d obtained between the bend of the road that is not actually traveling.
[0073]
Further, as described above, the current position (B) is obtained from among the candidate points, the current position (B) is obtained, and the next current position (B) is obtained last time for each candidate point obtained last time. If the candidate point is obtained for each, and the current position (B) is obtained from all the obtained candidate points, the candidate point that is the current position (B) obtained this time is If the obtained current position (B) is not the candidate point calculated as the previously obtained position, the position obtained based on the position that is not the position where the previously estimated vehicle exists is estimated as the position where the vehicle exists. That's right. 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 so far are not correct. can do.
[0074]
Similarly, when the vehicle bends approximately 90 degrees (for example, from 70 degrees to 110 degrees), Rsh1 and Rsh300 may be obtained as values significantly different from the values for obtaining the correct distance coefficient R. . This is because, for example, at an intersection having a plurality of lanes, a greatly different distance error d is obtained depending on which lane the vehicle has been turned on, so that a greatly incorrect Rsh1 or Rsh300 may be obtained depending on the turn. It is. Even when the vehicle bends at an angle smaller than approximately 90 degrees, on a road having a plurality of lanes, a different distance error d is obtained depending on which lane the vehicle travels and bends. It is smaller than the case where it bends. Therefore, in this embodiment, the deviation and influence when the vehicle is bent at an angle smaller than approximately 90 degrees are allowed.
[0075]
Therefore, in the present embodiment, when the current position (B) obtained in the process of FIG. 4 is not continuous with the previously obtained current position (B) (when there is a position jump), the current position (B) is bent by approximately 90 degrees. In this case, the value of Lcom (Ra + Rsh + Rshcb) obtained up to that time after the previous Ra is obtained is weighted with the distance traveled by that value, or Rsh1 or Rsh300 at that time is initialized. At the same time, 10 km is measured again.
[0076]
  However, if this is done, Rsh1 obtained from the time when Ra was obtained last time until the time when the current position (B) obtained last time is determined as the current position (B) or when the current position (B) is bent is approximately 90 degrees. And all information of Rsh300 is lost. Therefore, when this is done, for example, as shown in FIG. 8, even when the correct Rsh and Rsh300 are obtained halfway, this experience cannot be reflected in the distance coefficient R thereafter..Figure 8a shows a road that has not been accidentally driven after the road junction.InAfter estimating the current position (B),This is an example in which the current position (B) can be estimated on the road that is actually running, and FIG. 8b is an example in which the intersection is turned right after running on a smoothly curved road for a while.
[0077]
Therefore, in the present embodiment, the correction variable Rshcb is further introduced and the intersection is turned or the position on the road different from the road where the current position (B) has existed so far is obtained. Therefore, Lcom and Rsh1 or Rsh300 are obtained. In the case of initializing Rsh300, the Rsh300 that has been obtained up to that point in time from the time when Ra is obtained, and after the Rsh300 has been obtained, the next Rsh300 has not been obtained before traveling at least 2 km. Finds a value proportional to the Rsh300 and sufficiently smaller than the Rsh300, and sets the sum as Rshcb, and corrects the distance coefficient R by this value.
[0078]
Hereinafter, details of processing performed by the microprocessor 214 in order to calculate the correction variables Ra, Rsh1, Rsh300, and Rshcb in this manner will be described.
[0079]
First, FIG. 9 shows an initialization process performed when the apparatus is activated.
[0080]
In this process, all variables d, La, Rsh (Rsh1 / Rsh300), Ra, Rshcb, l, lcom, i, Rshcb_dt (i), and Rsh0 used in the subsequent processes are all initialized to zero.
[0081]
Next, FIG. 10 shows a process executed every time the vehicle travels 20 m after such an initialization process.
[0082]
In this process, the travel distance and travel direction calculated using each sensor 201, 202, 203 are read as sensor data (step 801). Next, the map data read from the CD-ROM 205 to the driver 206 is read (step 802).
[0083]
Next, a variable La representing the travel distance since the previous correction variable Ra was obtained, a variable Lshcb (i-1) representing the travel distance since the previous correction variable Rsh300 was obtained, and 20 m as the value at that time. Update by adding.
[0084]
Next, it is determined whether or not flag is 0 (step 804). The flag is a flag having a value of 1 only during a period in which the Rsh 300 is valid, that is, during a distance of 300 m after the distance error d is obtained and the Rsh 300 is calculated.
[0085]
If the flag is 0, the distance error d described above is obtained. Then, the value of the variable Lsh representing the travel distance since the previous correction variable Rsh1 was obtained is updated by adding 20 m to the value at that time (step 806).
[0086]
On the other hand, when the flag is 1, since it is a period in which Rsh300 is valid, that is, a period in which the distance error d is obtained and Rsh300 is calculated and the vehicle has not traveled 300 m, steps 805 and 806 are not performed.
[0087]
  Next, it is determined whether or not the distance error d obtained in step 805 is 0 (step 807). If the distance error d obtained in step 805 is not 0 and the distance error d is not 0 during the period when the Rsh 300 is valid, the Rsh calculation process in step 808 is performed. Note that the distance error d does not become zero during the period in which the Rsh 300 is valid because the distance error d used to obtain the Rsh 300 is maintained. In the Rsh calculation process (step 808), as described later, Rsh300 is calculated or Rsh1 is calculated from Rsh300. Further, in order to obtain Rshcb described above later, the value corresponding to the calculated Rsh300 is set to the array Rsh.cbThe process of saving in _dt is performed.
[0088]
Next, in step 809, it is determined whether or not the value of the variable Lsh representing the travel distance since the previous correction variable Rsh1 was changed exceeds 2 km. If the value is exceeded, the value of the previous correction variable Rsh1 is changed. A value obtained by multiplying Lsh representing the travel distance from the current value by Ra + Rsh + Rshcb at that time to Lcom at that time is defined as a new Lcom. This Lcom is used to calculate the correction coefficient Ra every 10 km as described above.
[0089]
Next, as described above, Rsh reduction processing is performed to gradually reduce the value of Rsh1 when the effective travel distance exceeds 2 km. 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, when the value obtained by subtracting the constant n from the positive Rsh1 becomes a negative value, Rsh1 is set to 0. Further, when the value obtained by subtracting the constant n from negative Rsh1 becomes a positive value, Rsh1 is set to 0. Further, when the value of Rsh1 is 0, it remains 0.
[0090]
Then, Lsh is reset to 0 again in order to manage the effective distance of Rsh subjected to the reduction process (step 812).
[0091]
On the other hand, in step 809, if it is not determined that the value of the variable Lsh representing the travel distance since the previous correction variable Rsh1 was changed does not exceed 2 km, the processing of steps 810 to 812 is not performed.
[0092]
Next, in step 813, a position that is not continuous with the current position (B) where the previously estimated vehicle exists is estimated as the current position (B) in the process of FIG. Determine if you have turned 90 degrees. If it is neither, the process is terminated.
[0093]
On the other hand, in the process of step 813, the current position (B) as the current position (B) is estimated as a position that is not continuous with the current position (B) where the previously estimated vehicle is present, or has it been bent approximately 90 degrees? As described above, the Lcom obtained up to that time (the value obtained by weighting the mileage for which the value was effective), or Rsh1 or Rsh300 at that time, as described above. Is initialized, and La reset processing is performed again to measure 10 km from that point (step 814). In this process, as described above, Rshcb is obtained and the distance coefficient R is corrected.
[0094]
Details of each process will be described below.
[0095]
First, the process for calculating the distance error d in step 805 will be described.
[0096]
FIG. 11 shows the procedure of this process.
[0097]
As shown in the figure, in this process, first, it is determined whether or not the vehicle has made a right or left turn (step 1101), it is determined whether or not a distance error exists (step 1102). The distance error d described in (1) 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.
[0098]
On the other hand, if the vehicle is not turning right or left, or if there is no distance error, the process is terminated.
[0099]
Next, the correction variable Rsh calculation process in step 808 of FIG. 10 will be described.
[0100]
FIG. 12 shows a processing procedure for calculating the correction variable Rsh.
[0101]
In this process, it is first determined whether or not flag is 0 (step 1201). When flag is 0, Rsh300 is not valid, and a non-zero distance error d is obtained (see FIG. 10), so that a correction variable Rsh300 is obtained according to the distance error d (step 1203). . However, before Rsh is changed, a value obtained by multiplying Lsh representing the distance traveled up to now by the value of Ra + Rsh + Rshcb after the value of correction variable Rsh1 was changed last time is added to that time Lcom. Is a new Lcom. Further, Rsh1 at that time is stored as Rsh0 (step 1202). The correction variable Rsh300 is obtained from the distance error d as follows.
[0102]
That is, the sign of the change dRsh given to the correction variable 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 obtained by multiplying the absolute value of the distance error d by a predetermined coefficient j. And Rsh300 is calculated | required according to Rsh300 = Rsh0 + dRsh.
[0103]
  Further, a value corresponding to the calculated size of Rsh300 is set., Rshcb_dt (i)(Step 1204), the above-mentioned flag is set to 1, and the variable l representing the travel distance after Rsh300 is calculated is set to 0 (step 1205), and the process is terminated. The variable l is used to determine whether or not the vehicle has traveled 300 m after Rsh300 is calculated.
[0104]
  Here, the registration in step 1205 is performed by the processing 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 it exceeds, there is no room for registering this value in the array, and the process is terminated. On the other hand, if not exceeded, the i-th element of the array Rshcb_dtRshcb_dt (i)As a result, a value obtained by multiplying a predetermined constant of Rsh300 is registered (step 1303), and the i-th element Lshcb (i) of the array Lshcb for representing the travel distance from when this Rsh300 is obtained until the next Rsh300 is obtained is obtained. It is set to 0 (step 1303). Then, i is incremented by 1 for the next process and the process is terminated.
[0105]
Thereafter, Lshcb (i-1) corresponding to Rshcb_dt (i-1) registered this time is sequentially updated until i is advanced by 1 in step 803 of FIG.
[0106]
By such a process, values proportional to the obtained Rsh300 are sequentially accumulated in the array Rshcb_dt. Further, in the array Lshcb, corresponding to each element of the array Rshcb_dt, the travel distance from when the Rsh300 in which the element is proportional to when the next Rsh300 is determined is sequentially accumulated.
[0107]
Now, returning to FIG. 12, if it is determined in step 1201 that the flag is not 0, since Rsh300 is still valid, l indicating the travel distance after Rsh300 is calculated exceeds 300 m. (Step 1206), if not exceeded, l is updated to represent the travel distance from the time Rsh300 is calculated to the present (step 1207), and the process ends.
[0108]
On the other hand, if l exceeds 300 m, a value obtained by multiplying l representing the travel distance from when the correction variable Rsh300 is calculated by the value of Ra + Rsh + Rshcb at that time to the value of Lcom at that time is added. A new Lcom is set (step 1208), distance errors d, l, and flag are reset to 0 (step 1209), and Rsh1 is obtained from Rsh300. Rsh1 is obtained by adding a value obtained by multiplying Rsh300 by a positive constant smaller than 1 to the stored Rsh0 (Rsh1 obtained last time) (step 1210). By this processing, Rsh is changed from Rsh300 to Rsh1.
[0109]
Note that a value sufficiently larger than Rsh1 may be used as dRsh, and Rsh300 = dRsh may be set for 300 m after Rsh300 is obtained.
[0110]
Next, the La reset process in step 814 in FIG. 10 will be described.
[0111]
FIG. 15 shows the processing procedure of this processing.
[0112]
As shown in the figure, in this process, i = 0 to imax (parallel data Lshcb For each i up to dt (the number of elements of dt) (steps 1501, 1505, 1506), it is determined whether or not Lshcb (i) exceeds 2 km (step 1502). A process of adding the value of dt (i) to Rshcb at that time (step 1503) is performed, and then Rshcb dt (i) is initialized to 0.
[0113]
Thereafter, i, Rsh, La, and Lcom are reset to 0 (step 1507), and the process is terminated.
[0114]
In the process of step 1507, the current position (B) in the process shown in FIG. In this case, Lcom (value obtained by weighting the mileage for which the value was effective to each value of Ra + Rsh + Rshcb) obtained from the previous time Ra is initialized, and Rsh at that time is initialized. From that point on, the travel distance of 10 km is measured again using La.
[0115]
In addition, by the processing from step 1501 to step 1506, the array Rshcb Of the values proportional to each Rsh300 accumulated in dt, Rshcb reflecting the value of the vehicle that has traveled 2 km or more is obtained.
[0116]
In the above, the process activated every 20 m shown in FIG. 10 has been described.
[0117]
Hereinafter, a process for obtaining the remaining correction variable Ra will be described.
[0118]
This process is performed when the vehicle travels 10 km after the previous Ra is obtained, or the current position (B) where the previously estimated vehicle is present is estimated as a position that is not continuous with the current position (B), or approximately 90 degrees. This is executed when you travel 10 km after making a turn.
[0119]
That is, it is executed when the variable La updated in step 803 in FIG. 10 exceeds 10 km.
[0120]
FIG. 16 shows the procedure of this process.
[0121]
As shown in the figure, in this process, as described above, Ra is set to a value Lcom obtained by weighting the mileage for which the value was effective to each value of R that is sequentially changed by Rsh1, Rsh300, and Rshcb during 10 km. make use of,
Ra = {(10 km + Lcom) / 10 km} −1
(Step 1601).
[0122]
When Ra is obtained, Rsh1, Rsh300, Rshcb, Lcom, La, Lsh, i are initialized to 0 (step 1602), and the process ends.
[0123]
The embodiment of the present invention has been described above.
[0124]
As described above, in this embodiment, the error of the distance coefficient R depends on the difference between the traveling state when it is assumed that the vehicle is traveling at the estimated current position and the actual traveling state represented by the sensor measurement value. Estimate and correct this. Therefore, no special external equipment for correcting the distance coefficient R is necessary, and appropriate correction can be performed regardless of the driving condition, and even when driving on a road with few features such as an intersection. Correction can be performed. Accordingly, it is possible to always calculate the travel distance with better accuracy and obtain the current position of the vehicle with higher accuracy. In addition, when the current position (B) is determined to be a position that is not continuous with the current position (B) obtained last time, or when an approximately 90 degrees turn at an intersection or the like, the error of the distance coefficient R is estimated. Even when it is difficult to obtain, the error of the distance coefficient R estimated before that can be reflected in the distance coefficient R to the extent corresponding to the reliability.
[0125]
【The invention's effect】
As described above, according to the present invention, in order to accurately determine the travel distance even when traveling on a road with few features, regardless of 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 with high accuracy by correcting the distance coefficient to be used.
[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 diagram showing a distance error d used in the present invention.
FIG. 8 is a diagram showing an example of a current position history displayed in an 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 a distance coefficient performed in an 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 a distance coefficient performed in an embodiment of the present invention.
FIG. 13 is a diagram showing a positive / negative correspondence relationship between a distance error d and a correction variable Rch used in one embodiment of the present invention.
FIG. 14 is a fifth flowchart showing a procedure of a process for correcting the distance coefficient performed in the embodiment of the present invention.
FIG. 15 is a sixth flowchart showing a procedure of processing for correcting a distance coefficient performed in an 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 switches
205 CD-ROM
206 CD-ROM driver
207 display
208 controller

Claims (3)

A current position calculation device for calculating a current position of a vehicle,
Means for storing map data representing a road map;
Means for detecting the traveling direction of the vehicle;
Sequentially, travel distance calculation means for calculating the travel distance of the vehicle using the number of pulses acquired from the vehicle speed sensor mounted on the vehicle and the set distance coefficient;
Means for sequentially estimating the road where the vehicle exists and the position where the vehicle exists on the road using the calculated travel distance of the vehicle, the detected traveling direction of the vehicle, and the road map represented by the map data. When,
Calculates the amount of deviation between the traveling state when the vehicle is traveling on the estimated position of the vehicle on the road and the traveling state of the vehicle obtained from the detected traveling direction and the calculated traveling distance Error calculating means for
When the error calculating means calculates the deviation amount, a correction amount determined according to the calculated deviation amount is obtained,
Seeking value with the correction amount and the predetermined relationship, the determined value, stored in association with the travel distance of the vehicle until then calculates the correction amount from seeking the correction amount ,
If the continuous non positions as there are vehicles in which the previously estimated is estimated as the position of presence of the vehicle, the correction amount is initialized to 0, the predetermined distance or more in the value that the memory A current position calculation comprising: a distance coefficient correction unit that calculates a total value of values associated with the travel distance and corrects the distance coefficient using the calculated total value. apparatus. A current position calculation device for calculating a current position of a vehicle,
Means for storing map data representing a road map;
Means for detecting the traveling direction of the vehicle;
Sequentially, travel distance calculation means for calculating the travel distance of the vehicle using the number of pulses acquired from the vehicle speed sensor mounted on the vehicle and the set distance coefficient;
Means for sequentially estimating the road where the vehicle exists and the position where the vehicle exists on the road using the calculated travel distance of the vehicle, the detected traveling direction of the vehicle, and the road map represented by the map data. When,
Calculates the amount of deviation between the traveling state when the vehicle is traveling on the estimated position of the vehicle on the road and the traveling state of the vehicle obtained from the detected traveling direction and the calculated traveling distance Error calculating means for
When the error calculating means calculates the deviation amount, a correction amount determined according to the calculated deviation amount is obtained,
Seeking value with the correction amount and the predetermined relationship, the determined value, stored in association with the travel distance of the vehicle until then calculates the correction amount from seeking the correction amount ,
If the vehicle has a substantially right angle turn right or left, with initializing the correction amount to 0, obtains the sum of values associated with the predetermined distance or more travel distance in the value that the memory Te, the current position calculating apparatus according to claim <br/> to and a distance factor correcting means for correcting the distance factor with the total value obtained said. The current position calculation device according to claim 1 or 2,
The error calculation means includes
A current position calculating device, wherein the amount of deviation is calculated when the vehicle bends due to running.

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