JPH0467300A - Vehicle position determining method - Google Patents

Abstract

PURPOSE:To determining the present running position of a vehicle by correcting with high accuracy the right turn or the left turn of the vehicle in an intersection. CONSTITUTION:An earth magnetism azimuth sensor 6 detects the running direction of a vehicle. When the vehicle is running along other road than an intersection area, whenever a car speed pulse is sent, a CPU 2 conjectures a running position of the vehicle by a dead-reckoning navigation, based on the running distance corresponding to a unit pulse and the running direction from the sensor 6. Subsequently, by allowing this conjectured position to match with a road in map data by matching correction, the present running position is determined. Also, when the vehicle goes into the intersection are, the present running position of the vehicle is determined by executing a prescribed correction.

Description

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

(B) Prior Art In current in-vehicle navigation devices, the current driving position of the vehicle is displayed superimposed on a map screen obtained by playing back a CD-ROM disc. Here, the current driving position of the vehicle is
This is obtained using a method called dead reckoning. Dead reckoning is a method in which, each time the vehicle travels one unit distance, the distance and direction of travel of the vehicle are vectorially added to the travel position one unit distance ago to obtain a new travel position.

The current driving position of the vehicle is obtained by matching the driving position obtained by such dead reckoning navigation with the roads on the reproduced map. FIG. 11 shows the principle of such matching. The road obtained by reproducing the CD-ROM disc links nodes (nl, n, . . . ) with C0+,
! ,...). here,
The current running position is obtained by selecting the point on the link that is the shortest distance from the running position obtained by dead reckoning. For example, in FIG. 11, the current traveling position is a'
In this case, if b is obtained by dead reckoning, matching is performed on this b, and the next current traveling position is b.
′ is determined. Similarly, the current driving position of the vehicle is sequentially determined by matching the driving positions determined by dead reckoning on the links.

However, such matching correction cannot be applied when the vehicle turns at an intersection or the like. Therefore, in such cases, other methods are used to correct the current traveling position of the vehicle. FIG. 12 is a diagram showing a case where a vehicle makes a right or left turn at an intersection. When the vehicle makes a left turn, the vehicle moves from M to P! and reaches Q. in this case,
The left turn completion point IQ of the vehicle is the distance traveled by the vehicle from the left turn point P to this point Q! , is corrected to the position itQ on the link added to the intersection center P. Further, when the vehicle makes a right turn, the right turn completion position S1 of the vehicle is similarly the travel distance of the vehicle from the right turn point P1 to this S! , is corrected to the position S on the link which is added to the intersection center P. In other words, the right/left turn completion position of the vehicle is corrected to a point on the link that is the sum of the travel distance of the vehicle from the right/left turn point to the right/left turn completion position and the center of the intersection.

(c) Problems to be Solved by the Invention However, in such a correction method, there is a position error l in the vehicle traveling direction between the actual right/left turn completion position of the vehicle and the corrected position. occurs. Here, when the vehicle turns right, the right-turn point P, approximately coincides with the intersection center P, so this position error IN becomes quite small; however, when the vehicle turns left, the left-turn point P, Since the intersection center P is far away, this positional error j becomes large. The larger the road, the larger this i becomes. An object of the present invention is to solve such problem.

(d) Means for solving the problem Detecting whether the turning direction of the vehicle is a right turn or a left turn,
Independent correction values are added to the center of the intersection in accordance with left and right turns to determine the right/left turn completion position.

(E) Effect Since independent correction values are added depending on whether the vehicle turns left or right, the above-mentioned position error that occurs when turning left does not occur.

(f) Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram of a navigation device according to this embodiment. In response to a command input from the input device (1), the CPU (2) issues a search reproduction command to the map reproduction device (3). In response to this command, the map playback device (3) reads the map data of the predetermined area from the CD-ROM disk,
This is transferred to CPU (2). CPtJ (2) transfers such data to RAM (4) and stores it therein.

The vehicle speed pulse sensor (5) emits pulses according to the rotation of the tires, and the vehicle travels 16 meters per pulse.

This pulse is sent to CPI, :(2). CPU (2
) uses this pulse as a timing pulse, which will be described later, and calculates the travel distance of the vehicle based on the number of 1,6 m x pulses.

The geomagnetic direction sensor (6) detects the traveling direction of the vehicle using geomagnetism. In this embodiment, the vehicle traveling direction is a rotation angle θ in the counterclockwise direction of the vehicle traveling direction with east as a reference.
It is expressed as. For example, when the vehicle is traveling north, the traveling direction is expressed as θ=90, and when the vehicle is traveling south, the traveling direction is expressed as θ=270. Such traveling direction data is taken into the CPU (2) in synchronization with the vehicle speed pulse being sent to the CPU (2).

When the vehicle is traveling on a road other than the intersection area (route determination area), the CPU (2) calculates the traveling distance according to the unit pulse and the traveling distance from the direction sensor (6) every time a 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 using the matching correction described in the conventional example to determine the current driving position.

Furthermore, when the vehicle enters an intersection area (route determination area), another correction, which will be described later, is performed to determine the current traveling position of the vehicle.

The CPU (2) creates a piece of 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 this on the display section. Transfer to (7). The display unit (7) receives this data and displays a map of the predetermined area including the current driving position of the vehicle.
The image will be displayed on a CRT screen installed inside the vehicle. still,
(8) is an R that stores the operating program of CPU (2).
OM (Read Only Memory).

Next, a method of correcting the current traveling position of the vehicle when the vehicle is making a turn at an intersection will be described. Such correction is performed only when the vehicle is within an intersection area (an area within a circle with a predetermined radius centered on the intersection center) and the vehicle makes a left or right turn. Therefore, if a left turn or right turn is detected while the vehicle is outside the intersection area, this correction is not performed, and the current driving position of the vehicle is updated by dead reckoning and matching as described above. Note that when the vehicle does not turn left or right within the intersection area, the current traveling position of the vehicle is determined by dead reckoning navigation.

The left and right turns of the vehicle are determined by F I F O (Fas
This is done using a tIn Fast out) buffer. Data indicating the running direction of the vehicle, which is side-ratio-referenced by the azimuth sensor (6), is input to this buffer in order from D in synchronization with the vehicle speed pulse. Also, the old data is output in order from A in synchronization with the vehicle speed pulse.

Such a buffer consists of 150 areas. The traveling direction data inputted from D is outputted from A when 150 vehicle speed pulses have been issued since the time of input. Therefore, in the leftmost area of the FIFO buffer, the running direction of a running position that is 1.6 m x 150 = 240 m backward from the current running position is stored. The FIFO buffer is divided into three areas each having 50 areas. Flat t of each area
l: When calculating the J value, the average value θ of area 3 is obtained as the average value of the vehicle's driving direction from the current driving position to the driving position 80m back, and similarly from the current driving position to the driving position 80m back. The average value θ of region 2 is obtained as the average value in the traveling direction of , and the average value θ1 of region 1 is further obtained as the average value of the traveling direction from the traveling position to the traveling position 80 meters back.

The determination of whether the vehicle is turning left or right is made by comparing θ and θ. Figures 3(a), 3(b), and 3(c) show the driving route of the past 240 meters when the vehicle went straight, turned left, and turned right. The parts corresponding to area 1, area 2, and area 3 of the FIFO buffer are divided into division points A, B, C, and D every 80 m.
It is indicated by separating with .

When the vehicle is traveling straight, θ, ←θ. When the vehicle turns left, the traveling direction is represented by a counterclockwise rotation angle with respect to the bundle, so θ, >θ. In addition, when the vehicle turns right, the angle becomes θ, θ. Therefore, if θ, -θsho, it is determined that the vehicle has turned left, and
If θ1-θ,>o, it is determined that the vehicle has turned right.

Furthermore, the angle θ of right and left turns is determined by θ,=θ1−θ. Whether the vehicle has completed a right or left turn at an intersection is determined by detecting that θ□ matches the bending angle of the road. For example, when the intersection is in the state shown in Figure 4, θ
, = θ2, θLl+”θ.

Alternatively, by detecting θ,=θ, it is determined that the vehicle has turned left or right and has proceeded to branch road 1, branch road 2, or branch road 3. In this case, θ.

takes a negative value. As described above, whether the vehicle is turning right or left is determined.

After determining whether the vehicle is turning left or right, the current driving position of the vehicle is corrected by adding 120 m (half of the past route) from the center of the intersection to the selected route in the case of a right turn. (Rn). This is the fifth
As shown in the figure, when the right turn is completed in this way, the right turn is made based on the fact that the midpoint (P,) of the past route substantially coincides with the intersection center (P).

(1) When turning right: Rn = P+ 120-(1) However, when turning left, the midpoint (P,) of the past route does not pass through the center of the intersection (P). Here, the midpoint of the past path (P
, ) coincides with the center of the left turn curve, the current driving position is determined by the same process as when turning right above, and there is a difference between the current driving position determined in this way and the actual current driving position of the vehicle. , Δi errors occur. Such Δl can be approximated by Δl = a sin θ (θ is the bending angle of the road), where a is the edge 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.

(11) When turning left Rn=P+120+△2...(
2) However, in reality, in such a left turn, the length of the curve arc of the vehicle is smaller than in a right turn, so if the length of the past route is made the same as that for a right turn, θ, = θ.

The midpoint of the past route when the path becomes , does not coincide with the center of the curve, but shifts backward by α. Therefore, strictly speaking, the current traveling position at the time of the left turn may be defined by the following equation, taking into account such deviation.

(ii') When turning left Rn=P+120+△l-△α
(3) Here, Δa is set to about 20 m.

FIG. 8 shows a flowchart for determining the current running position of the vehicle when turning right or left as described above, and the operation will be summarized. When it is determined that the vehicle has entered the intersection (step 1>, R
The shape information of the intersection (number of branch roads N, bending angles of branch roads θ1, θ1, ... θ9, road width a, etc.) is read from AM (4) (step 2). Next, the road change angle θ of the vehicle is calculated (step 3), and whether the vehicle is turning left or right is determined depending on whether θ is positive or negative (step 4.5). When a left turn is determined in step 4, it is determined whether the course change angle θL8 matches any of the bending angles of the branch road (steps 6 to 9). If no match is found here, step l
Return to and repeat the above operation.

When the collision 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 11). On the other hand, if a right turn is determined in step 6, then steps 6 to
Processing substantially similar to step 11 is performed (steps 12 to 17).
. However, the determination of the current driving position in step 16 is
The first equation is followed.

Incidentally, the deviation α during a left turn can also be eliminated by making the size of the past route when turning left smaller than when turning right (reducing the size of area 2 of the FIFO buffer). 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 set to 30. Therefore, the size of the past route when turning left is 1.6 x 130 = 208 (m),
The size of the past route corresponding to area 2 is 1.6X30=4
It becomes 8 (m). By setting in this way, it is possible to make the midpoint of the past route when turning left approximately coincide with the center of the left-turning curve, and therefore the current traveling position when turning left can be adjusted in the next direction without having to correct the current driving position according to a above. It can be defined as follows.

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

The method for determining the current driving position when a vehicle turns left or right at an intersection has been explained above, but the determination of the number of FIFO buzzer areas, etc. is based on experience to minimize the error as much as possible, taking into account the width of Japanese roads, etc. It has been decided. However, the present invention is not limited to the above embodiments, and the number of areas and the like can be changed as necessary. Furthermore, the number of areas may be changed for each intersection.

(G) Effects of the Invention As described above, according to the present invention, the current traveling position of the vehicle can be corrected with high accuracy regardless of whether the vehicle is turning right or left at an intersection.

[Brief explanation of drawings]

Fig. 1 is a circuit block diagram showing an embodiment, Fig. 2 is a diagram showing a FIFO buffer used in the embodiment, and Fig. 3 is a circuit block diagram showing an embodiment.
FIG. 4 is a diagram showing an example of an intersection. FIGS. 5 and 6 are diagrams showing the state of right and left turns in the same embodiment. FIG. 8 is a diagram showing the state of left and right turns in the same embodiment. FIG. 7 is a diagram showing the right and left turn states of another embodiment, FIG. 9 is an operation flowchart of another embodiment,
FIG. 10 is a diagram showing a FIFO buffer of another embodiment, FIG. III is a diagram for explaining a matching method, and FIG. 12 is a diagram showing right and left turns at an intersection. (2)...CPU, (3)...Map playback device, (8)...ROM.

Claims (1)

[Claims] (1) A vehicle running position detection method comprising: reproducing a storage medium to obtain predetermined map data; and determining a vehicle position on a map based on the map data, the method comprising: determining the vehicle position; The steps include detecting that the vehicle has entered the intersection, detecting whether the vehicle is turning left or right within the intersection, and independently updating the intersection data P in the map data in accordance with the right or left turn of the vehicle. A vehicle position determination method characterized by supplementing supplementary value data L_1 or L_2 to obtain the current traveling position of the vehicle when turning right or left.