JP2675427B2 - Vehicle position determination method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a vehicle position determination method suitable for use in a vehicle-mounted navigation device or the like.

(B) Conventional technology In the current vehicle-mounted navigation device, the current traveling position of the vehicle is overlaid and displayed on the map screen obtained by reproducing the CD-ROM disc. Here, the current traveling position of the vehicle is obtained by using a method called dead reckoning. Dead reckoning is a method of obtaining a new traveling position by vectorically adding the traveling distance and traveling direction of the vehicle to the traveling position one unit before each time the vehicle travels one unit distance.

The current traveling position of the vehicle is obtained by matching the traveling position obtained by such dead reckoning on the road on the reproduction map. FIG. 11 shows the principle of such matching. The road obtained by reproducing the CD-ROM disc is defined by connecting nodes (n ₁ , n ₂ ...) With links (l ₁ , l ₂ ...). Here, the current traveling position is obtained by selecting the point on the link that has the shortest distance from the traveling position obtained by dead-reckoning. For example, the eleventh
In the figure, when b is obtained by dead reckoning when the current traveling position is a ', matching is performed for this b, and the next current traveling position is determined as b'. Similarly, the current driving position of the vehicle is sequentially determined by matching the dead reckoning driving position on the link.

However, the correction by such matching cannot be applied when the vehicle turns at an intersection or the like. Therefore,
In such a case, another method is used to correct the current traveling position of the vehicle. FIG. 12 is a diagram showing a case where a vehicle turns right or left at an intersection. When the vehicle makes a left turn, it goes from M ₂ through P ₂ to Q ₂ . In this case, turn completion position Q ₂ of the vehicle, a travel distance l ₂ of the vehicle from the left point P ₂ of the vehicle up to the Q _2, is corrected to a position Q on the link obtained by adding the intersection center P. Also, right turn completion position S ₁ of the vehicle when the vehicle makes a right turn likewise, the position S on the link obtained by adding the travel distance l ₁ of the vehicle from the right turn point P ₁ to the S ₁ to the intersection center P Will be corrected. That is, the right / left turn completion position of the vehicle is corrected to a point on the link in which the traveling distance of the vehicle from the right / left turn point to the right / left turn point is added to the intersection center.

(C) Problem to be Solved by the Invention However, in such a correction method, a position error l _x in the vehicle traveling direction is generated between the actual right / left turn completion position of the vehicle and the corrected position. Here, when the vehicle makes a right turn, the right turning point P ₁ substantially coincides with the intersection center P, so this positional error l _x becomes considerably small, but when the vehicle makes a left turn,
Since the left turning point P ₂ and the intersection center P are separated from each other, the position error l _x becomes large. The larger the road, the larger this l _x . An object of the present invention is to eliminate such l _x .

(D) Means for solving the problem It is detected whether the vehicle is turning right or left, and independent correction values are added to the intersection center depending on whether the vehicle is turning left or turning right. And

(E) Action Since the correction values independent of each other are added according to the left turn and the right turn of the vehicle, the above-mentioned position error occurring at the time of left turn does not occur.

(F) Example Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit block diagram of the navigation device according to the present embodiment. In response to the command input from the input device (1), the CPU (2) issues a search / playback command to the map playback device (3). In response to this command, the map reproducing device (3) reads the map data of the predetermined area from the CD-ROM disc and transfers it to the CPU (2). CPU (2) sends such data to RA
Transfer to M (4) and store in it.

The vehicle speed pulse sensor (5) emits a pulse according to the rotation of the tire, and the vehicle travels by 1.6 m per pulse.
This pulse is sent to the CPU (2). The CPU (2) uses this pulse for the timing pulse described later, and 1.
The mileage of the vehicle is calculated from 6m x number of pulses.

The geomagnetic direction sensor (6) detects the traveling direction of the vehicle by utilizing the geomagnetism. In this embodiment, the traveling direction of the vehicle is represented by the counterclockwise rotation angle θ of the vehicle traveling direction with reference to the east. For example, when the vehicle is traveling north, the traveling direction is represented by θ = 90, and when the vehicle is traveling south, the traveling direction is represented by θ = 270. The vehicle speed pulse is CP
It is taken in by the CPU (2) in synchronization with being sent to the U (2).

When the vehicle is traveling on a road other than the intersection area (route determination area), the CPU (2) travels from the azimuth sensor (6) and the traveling distance according to the unit pulse every time the vehicle speed pulse is sent. The driving position of the vehicle is estimated by dead reckoning based on the direction. Then, this estimated position is matched with the road in the map data by the matching correction described in the conventional example to determine the current traveling position.
Further, when the vehicle enters the intersection area (route determination area), another correction described later is performed to determine the current traveling position of the vehicle.

The CPU (2) creates one image data based on the data representing the current traveling position of the vehicle created in this way and the map data stored in the RAM (4), and displays it on the display unit. Transfer to (7). The display unit (7) receives this data and displays a map of a predetermined area including the current traveling position of the vehicle on a CRT screen or the like installed in the vehicle. still,
(8) is a ROM storing the operation program of the CPU (2)
(Read Only Memory).

Next, a method of correcting the current traveling position of the vehicle when the vehicle turns at the intersection will be described. Such correction is executed only when the vehicle is in the intersection area (area within a circle having a predetermined radius centered on the center of the intersection) and the vehicle makes a left turn or a right turn. Therefore, when a left turn or a right turn is detected when the vehicle is outside the intersection area, this correction is not executed, and the current traveling position of the vehicle is updated by dead reckoning and matching as in the above. When the vehicle does not turn right or left in the intersection area, the current traveling position of the vehicle is determined by dead reckoning.

When turning left or right of the vehicle, the FIFO (Fast In Fast o) shown in Fig. 2 is used.
ut) It is done using buffers. In such a buffer,
Data indicating the traveling direction of the vehicle detected by the direction sensor (6) is sequentially input from D in synchronization with the vehicle speed pulse. The old data is sequentially output from A in synchronization with the vehicle speed pulse. Such a buffer consists of 150 areas. The traveling direction data input from D, when 150 vehicle speed pulses are issued from the time of input,
It is output from A. Therefore, in the leftmost area of the FIFO buffer, the traveling direction of the traveling position which is traced back 1.6 m × 150 = 240 m from the current traveling position is stored. The FIFO buffer is divided into three areas of 50 areas each. When the average value of each area is calculated, the average value θ ₃ of the area 3 is calculated as the average value in the traveling direction of the vehicle from the current traveling position to the traveling position 80 m back.
Similarly, the average value θ ₂ of the area 2 as the average value in the traveling direction from the traveling position to the traveling position 80 m back is
Further, the average value θ ₁ of the region ₁ is obtained as the average value in the traveling direction from the traveling position to the traveling position 80 m back.

The decision as to whether the vehicle is turning right or left is made by comparing θ ₁ and θ ₃ . The vehicle goes straight to Fig. 3 (a) (b) (c),
The following shows the travel route of the past 240m when turning left and right. FI
The portions corresponding to the area 1, area 2, and area 3 of the FO buffer are shown by being divided by the division points A, B, C, D every 80 m. When the vehicle is traveling straight, θ ₁ ≈θ ₃ . When the vehicle turns left, the traveling direction is represented by the counterclockwise rotation angle with respect to the east, so θ ₃ > θ
It becomes ₁ . When the vehicle turns right, conversely, θ ₃ <θ ₁ . Therefore, if θ ₁ −θ ₃ <0, it is determined that the vehicle turned left, and if θ ₁ −θ ₃ > 0, it is determined that the vehicle turned right.

Further, the angle θ _LR for turning left or right is _calculated by θ _LR = θ ₁ −θ ₃ . The determination that the vehicle has completed a right / left turn at the intersection is made by detecting that θ _LR matches the bend angle of the road. For example, when the intersection is in the state shown in Fig. 4,
By detecting θ _LR = θ ₁ , θ _LR = θ ₂ or θ _LR = θ ₃ , it is determined that the vehicle has made a left turn or a right turn and proceeded to branch road 1, branch road 2 or branch road 3. . In this case,
θ ₃ has a negative value. As described above, it is determined whether the vehicle is turning left or right.

The correction of the current driving position of the vehicle after the vehicle is judged to turn right or left is corrected by adding 120 m (half of the past route) to the selected route from the center of the intersection in the case of turning right. (Rn). This is based on the fact that the midpoint (P ₁ ) of the past route substantially coincides with the intersection center (P) at the time when the right turn is completed, as shown in FIG. .

(I) When turning right Rn = P + 120 (1) However, when turning left, the midpoint (P ₂ ) of the past route does not pass through the intersection center (P). Here, if the midpoint of the past route (P ₂ ) coincides with the center of the left turn curve, if the current traveling position is determined by the same processing as that for the right turn, the current traveling position and the actual traveling position thus determined are determined. An error of Δl occurs between the current traveling positions of the vehicles. Such Δl can be approximated by Δl = a sin θ (θ is the bending angle of the road), where a is the roadside of the road. Therefore, in this case, the current traveling position of the vehicle may be determined to be a position obtained by adding 120 m + Δl on the selected route from the center of the intersection.

(Ii) When making a left turn Rn = P + 120 + Δl (2) However, in reality, in such a left turn, the length of the curve arc of the vehicle is smaller than that in the right turn. If set, the midpoint of the past route when θ _LR = θ _k does not coincide with the center of the curve, and α
Just shift. Therefore, strictly speaking, the current traveling position at the time of the left turn may be defined by the following equation in consideration of the deviation.

(Ii ') When turning left Rn = P + 120 + Δl−Δα (3) Here, Δα is set to about 20 m.

A flow chart for determining the current traveling position of the vehicle at the time of turning to the right or left is shown in FIG. 8 and the operation is summarized.
If it is determined that the vehicle has entered the intersection (step 1),
The shape information of the intersection (the number of branches N, the bending angles θ ₁ , θ ₂ , ... θ _{N of} the branches, the road width a, etc.) is read from the RAM (4) (step 2). Next, the road change angle θ _LR of the vehicle is calculated (step 3), and it is determined whether the vehicle is turning left or right depending on whether θ _LR is positive or negative (steps 4 and 5). When the left turn is determined in step 4, it is determined whether or not the course change angle θ _LR matches any of the bend angles of the branch roads (steps 6 to 6).
9). If no match is detected here, the process returns to step 1 and the above operation is repeated. When a match is detected, the current traveling position Rn is determined according to the third equation (step 10), and then the current traveling position Rn is updated according to dead reckoning (step 1).
1). On the other hand, if a right turn is determined in step 6,
The same processing as steps 6 to 11 is performed (steps 12 to 17). However, the determination of the current traveling position in step 16 follows the first expression.

By the way, the shift α at the time of left turn can be eliminated by making the size of the past route at the time of left turn smaller than that at the time of right turn (the size of the area 2 of the FIFO buffer is made smaller). Examples are shown in FIGS. 7 and 10. In this embodiment, the number of areas in the second area of the FIFO buffer when turning left is 30. Therefore, the size of the past route at the time of turning left is 1.6 × 130 = 208 (m), and the size of the past route corresponding to the area 2 is 1.6 × 30 = 48 (m). By setting in this way, the midpoint of the past route at the time of left turn can be made to substantially coincide with the center of the left turn curve, so that the current running position at the time of left turn can be made as follows without correction by α. Can be defined as

(Ii ″) When turning left Rn = P + 104 + Δl (4) FIG. 9 shows a flowchart for determining the current running position of the vehicle when the area division of the FIFO buffer is changed according to the turning left or right.

The method of determining the current driving position when the vehicle turns right or left at the intersection has been described above, but empirically when determining the number of FIFO buffer areas, etc. I have decided. However, the present invention is not limited to the above embodiment, and the number of such areas and the like can be appropriately changed as necessary. Furthermore, the number of areas may be changed for each intersection.

(G) Effect of the Invention As described above, according to the present invention, the current traveling position of the vehicle can be accurately corrected regardless of whether the vehicle turns right or left at the intersection.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing an embodiment, FIG. 2 is a view showing a FIFO buffer used in the embodiment, FIG. 3 is a view showing a state of a past route in the embodiment, and FIG. 4 is an intersection. FIG. 5, FIG. 6 and FIG. 6 are views showing an example of a right / left turn state in the same embodiment, FIG. 8 is an operation flowchart of the same example, and FIG. 7 is a right / left turn state of another embodiment. Showing the figure,
FIG. 9 is a flowchart of the operation of the other embodiment, FIG.
FIG. 11 is a diagram showing a FIFO buffer of another embodiment, FIG. 11 is a diagram for explaining a matching method, and FIG. 12 is a diagram showing right and left turns at intersections. (2) …… CPU, (3) …… Map playback device, (8) …… R
OM.

Claims (1)

(57) [Claims] 1. A vehicle traveling position detecting method comprising: a step of reproducing a storage medium to obtain predetermined map data; and a step of determining a vehicle position on a map based on the map data. The step of determining is to detect that the vehicle has entered the intersection, the step of detecting a right or left turn of the vehicle within the intersection, and the supplementary to the intersection data P in the map data according to the right or left turn of the vehicle. A vehicle position determining method, wherein value data is added to obtain a current traveling position of the vehicle at the time of turning left or right.