JP2709635B2 - Current position display device of moving object - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a moving body current position display device that displays a moving body on a road map projected on a screen in advance while obtaining the current position of the moving body.

Conventional technology Conventionally, for example, when driving a mobile body such as a car in an unguided area, in order to provide appropriate guidance so that the driver does not get off the scheduled course and lose his way, a distance sensor and a direction sensor are provided. The current position on the two-dimensional coordinates is obtained by calculation while detecting the traveling distance and the traveling direction of the moving object, respectively, and the current position that changes every moment as the moving object travels is displayed on the screen in advance. 2. Description of the Related Art A current position display device for a moving object has been developed which enables a driver to confirm a current position by sequentially updating and displaying the current position on a road map with point information.

Thus, in such a current position display device of a moving body,
The occurrence of position errors due to factors such as the accuracy of each sensor of the distance sensor and the direction sensor and the calculation accuracy of the significant digits at the time of calculating the current position cannot be denied. There is a problem that the displayed current position gradually deviates from the road on the map, and it becomes impossible to determine on which road on the map the vehicle is traveling.

Also, even if there is no error in the calculated current position of the moving object, if the current position is displayed on the map itself, the current position displayed on the screen will deviate from the road on the map. Become.

Therefore, conventionally, in order to correct the current position deviating from the road on the map, the travel obtained by storing and holding the data of the current position that is sequentially updated according to the road pattern on the map and the travel of the moving object is stored. The matching process with the trajectory pattern is periodically performed so that the traveling trajectory is adjusted on the matched road to correct the current position of the moving body (Japanese Patent Laid-Open No. 1-41717).
Reference).

At that time, conventionally, a pattern of a traveling locus to be matched and a pattern of a road are each approximated by a line segment having the same length, and the two patterns approximated by the respective broken lines are matched with each other, and the two patterns in the two patterns correspond to each other. The matching is performed so that the sum of the angle differences of the respective line segments is minimized, but the accuracy of the matching is not always sufficient.

The present invention has been made in consideration of the above points, and performs matching processing between a road pattern on a map and a traveling trajectory pattern of a moving object to match a traveling trajectory on a matched road. It is an object of the present invention to provide a moving body current position display device which can accurately adjust a traveling trajectory on a matched road when correcting the current position of the moving body. .

Configuration Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an example of the configuration of a moving body current position display device according to the present invention. For example, a distance sensor 1 that outputs a pulse signal for each unit traveling distance in accordance with the rotation of a tire of the moving body, and a yaw sensor, for example, A direction sensor 2 based on a rate system that detects the angular velocity of the direction change and outputs a signal proportional to the amount of direction change accompanying the traveling of the moving object, and counts the number of pulse signals from the distance sensor 1 to determine the traveling distance of the moving object. The current position on the X-Y coordinates for each fixed traveling distance of the moving object is obtained by sequential calculation by measuring and deviating the traveling direction according to the output signal of the direction sensor 2, and the current position display device of the moving object A signal processing device 3 including a microcomputer for performing overall control;
A running trajectory storage for sequentially storing data of the current position on the XY coordinates, which changes momentarily according to the running of the moving body obtained by the signal processing device 3, and stores the data as finite continuous position information of the moving body. A device 4, a map information storage medium 5 in which information of a plurality of road maps is stored in advance,
A storage medium reproducing device 6 for selectively reading information of a road map from the storage medium 5; a predetermined road map is displayed on a screen based on the read map information; The operation command is given to the display device 7 for displaying the current position of the moving object together with the traveling locus and the traveling direction of the moving object at the current position as necessary, and the signal processing device 3. The user selects and specifies a map to be displayed on the display device 7 and sets the starting point of the moving object on the displayed map, and selectively gives a display command such as a traveling locus to display the displayed map and the traveling locus. To change the setting of the display mode, such as changing the direction of the display, shifting the display position, partially enlarging the map and travel trajectory, selecting the display scale, etc. It is constituted by an operating device 8 that can.

In such a configuration, the selectively read map is displayed on the screen of the display device 7, and the signal processing device 3 executes the moving object from the starting point set on the map. The current position on the XY coordinates is calculated every moment in accordance with a preset scale of the map, and the calculation result is sequentially sent to the travel locus storage device 4 to update the stored contents. The stored contents are constantly read and sent to the display device 7.

Accordingly, the display device 7 displays, for example, as shown in FIG. 2, a display mark M1 indicating the current position of the moving object on a map displayed on the screen, and indicates a traveling direction of the moving object at the current position. The display mark M2 and the display mark M3 of the traveling locus from the starting point ST to the current position are simulated following the traveling state of the moving object.

The above configuration and operation are the same as those of the conventional moving object current position display device described at the beginning.

Accordingly, in such a moving body current position display device, as shown in FIG. 3, the current position and the running locus gradually deviate from the road on the map as the moving body travels due to the accumulated error described above. Eventually, it becomes impossible to determine which point on the map the vehicle is currently traveling.

In such a current position display device for a moving object, when the current position of the moving object and the traveling locus up to that point deviate from a road on the map, the signal processing device 3 will be described below. Of the road and the traveling locus pattern of the moving object are matched, and the road on which the matching tag of the pattern is taken is regarded as the currently traveling road, and the traveling locus is adjusted on the road to match the traveling locus. The current position and the display position of the traveling locus are corrected.

At this time, when matching the pattern of the traveling locus with the pattern of the road, for example, the traveling locus of the moving body, such as a road along the traveling locus of the moving body or a road within a certain distance range from the current position of the moving body, or A road having a certain correlation with the current position is extracted as a candidate for a road to be matched, so that the burden of the matching process is reduced.

A specific example of the extraction of the candidate road will be described below.

First, the estimated current position of the moving object is set on the currently running road on the map and on all the roads branching from the road in accordance with the fixed traveling distance of the moving object.

At this time, as shown in FIG. 4 (a), if there is no branch road within a certain distance L from the set point of the previous estimated current position x ', as shown in FIG. Therefore, the estimated current position x is added to the position advanced by the certain distance L.
Set. Further, as shown in FIG. 4 (b), if there is a branch within the fixed distance L, the estimated current positions x1, x2, x3 are set for all of the branches. Where l1 +
l2 = l1 + l3 = l1 + l4 = L.

Each time the distance sensor 1 detects that the moving object has traveled the fixed distance L, the estimated current position is set in the road position data on the map displayed on the screen of the display device 7 at that time. Therefore, it is automatically performed under the control of the signal processing device 3. The setting of the estimated current position may be performed by setting the estimated current position every time a predetermined time elapses along with the traveling of the moving object, without depending on the traveling distance of the moving object. It is also conceivable to make the setting interval of the estimated current position variable according to the traveling state of the moving body. Each road is divided into lines, and position data on XY coordinates of each line segment is stored in the map information storage medium 5.

Next, it is determined whether or not the distance between the estimated current position set as described above and the current position of the moving object calculated and displayed off the road is within a predetermined allowable range. Judge, select the estimated current position within the range,
Only the road on which the selected estimated current position exists is set as a candidate for matching.

Now, for example, in the relationship of FIG. 5, the estimated current position x
The distance between (x1, x2, x3) and the current position P is D (D1, D2, D
In the case of 3), an estimated current position that satisfies the following equation: D ≦ αL + M (1) is selected.

Here, M is a preset allowable range, for example,
It is set to about 50m. α is a coefficient relating to the positional accuracy when the traveling distance of the moving body is used as a parameter, and is set to, for example, about 5%. L is set to about 100 m.

At this time, it is also conceivable to select an estimated current position set on a road having a direction within a certain allowable angle difference with respect to the traveling direction of the moving body at the current position P. .

If the value of M is set to a relatively small value in the relationship of FIG. 5, for example, only x2 is selected as the estimated current position that satisfies the condition of Expression (1), and the estimated current position x2 does not exist. Is determined as a candidate road to be subjected to the matching process.

Therefore, even when there are many roads in the vicinity of the current position off the road, it is possible to select a candidate for a road that has a high probability of being subjected to matching to be subjected to the matching process, to a minimum. The burden of the matching process is effectively reduced.

Further, when matching the pattern of the traveling locus of the moving object with the pattern of the candidate road, if the moving object travels a certain distance and the specified current position is sequentially set, the processing load is large. Therefore, the amount of change in the direction of the traveling locus of the moving object is constantly monitored, and when the integrated value of the amount of the direction change becomes larger than a certain value, it is considered that a great feature has occurred in the change in the shape of the traveling locus. ,
At that time, matching processing according to the pattern of the traveling locus of the moving object during the integration period up to that time is executed at a time.

That is, as shown in FIG. 6, an angle wi (i = 0, 1, 2,) between the traveling locus at each point a, b, c, d,. 3,...) Are calculated, and the integrated value W of the direction change amount is sequentially calculated according to the following equation.

When the calculated total amount W of the change in direction becomes equal to or greater than a preset value, traveling from the current position P of the moving body at that time to the previous start point a (becomes the previous matching processing point). The trajectory is extracted as a target of the current matching process.

Therefore, if the extracted pattern is matched with the road in accordance with the traveling locus of the moving body having a large feature, the number of times of the matching process is reduced as a whole, and the accuracy is high according to the feature of the pattern. An efficient matching process can be performed.

At this time, as the pattern of the road to be matched, as shown in FIG. 7, for example, the estimated current position x selected according to the current position P of the moving object as described above is used as the head, A road pattern that connects the set points of the past estimated current positions x ′ up to S is cut out.

When a pattern of a road on which a plurality of estimated current positions are set is cut out and matching processing is performed at a time, each estimated current position that satisfies the relationship of the expression (1) is selected as described above. At each point in time, the distance between the current position of the moving object at that time and the estimated current position set on the road gradually increases as the moving object moves, , It is necessary to increase the value of M in the expression (1).

In the case where the extracted pattern of the traveling locus of the moving object is matched with the pattern of the candidate road cut out as described above, for example, the pattern of the traveling locus LP as shown in FIG. Is approximated by a line segment of equal length, and the pattern of the candidate road RP is also approximated by a line segment of equal length as shown in FIG. 8 (b). Matching is performed using a vector sequence of each line segment.

If the traveling locus of such a moving object and the road on the map are matched with each other using a pattern obtained by approximating a broken line under the same condition, the direction and position of each corresponding line segment can be easily compared with each other. And the matching process can be easily and accurately performed.

In addition, as a specific processing means for matching a traveling trajectory pattern approximated by a line segment of equal length with a road pattern, a known pattern matching method is widely applied.

Then, as shown in FIG. 9, the road RP 'approximated by a product line using equal-length line segments whose patterns have been matched.
Travel trajectory so that the leading current position P of the travel trajectory LP ′, which is also approximated by a line of equal length, is located at the head position of
After the translation of LP ', the traveling trajectory LP' is rotated by an angle θ about the point P as shown in FIG. 10 so as to be fitted on the matching road RP '.

At this time, the running locus approximated by a broken line using equal length line segments
Vector sequence of each line segment of LP ′ , And a vector sequence of each line segment by the following equation (3) Vector sequence obtained by rotating , The rotation of the traveling locus LP ′ is executed.

In such a case, in the present invention, the traveling locus LP '
Is rotated by an angle θ about the point P and fitted on the matched road RP ′, in order to perform the fitting with high accuracy, each corresponding line in the traveling locus LP ′ and the road RP ′ The sum of the squares of the difference between the absolute positions is calculated to obtain the position correlation, and the rotation angle θ of the traveling trajectory LP ′ that minimizes the obtained position correlation is determined. Features.

Now, in the relationship shown in FIG. 9, when the point P is set as the origin on the XY coordinate, the leading positions of the respective line segments of the traveling trajectory LP 'are (p1, q1), (p2, q2),. , qn) and road RP '
(L1, m1), (l2, m2), ..., (l
n, mn), a vector sequence of each line segment of the traveling locus LP ′ Vector sequence for each line segment of road and road RP ' Is expressed by the following equations (4) and (5), respectively.

Also, a vector sequence when the traveling locus LP ′ is rotated by the angle θ as described above. Is represented by the following equation (6).

Then, a vector sequence of the rotated traveling locus LP ′ Vector sequence of each line segment of road and road LP ' Then, the correlation corr between the position of the rotated traveling locus LP ′ and the road RP ′ is obtained according to the following equation (7).

It is.

Further, since the accuracy of the current position calculated as the traveling of the moving body advances decreases, ωi When using the above data, a predetermined value is determined in advance in accordance with the sensor accuracy of the distance sensor 1 and the direction sensor 2 when calculating the current position of the moving object, the calculation accuracy, and the like, so that the weight of the past data is reduced as the past data becomes. This is a weight coefficient set as a function.

Thus, from the relationship of equation (7), when θ = −α, corr
Is set to a minimum value, and the position correlation corr can be minimized by setting the rotation angle θ of the traveling locus LP ′ to be −α.

Thus, according to the present invention, the traveling locus LP 'and the road RP'
So that the sum of the squares of the difference between the head positions of the corresponding line segments in the traveling locus LP ′ and the road RP ′ is minimized so that the difference between the absolute positions on the XY coordinates of The running locus LP 'is rotated at an appropriate angle θ to match the road RP', so that the matching is performed by the rotation angle such that the sum of the angle differences of the corresponding line segments is minimized as in the related art. Compared to the case, it is possible to perform a more accurate matching such that the degree of coincidence between the traveling locus LP ′ and the road RP ′ becomes higher.

Further, according to the present invention, when the above-described fitting process is performed, the traveling locus L approximated by a broken line by equal length line segments
The processing of each corresponding line segment in P 'and the road RP' can be individually and concurrently processed.

Therefore, the matching process can be easily performed at high speed, and the process can be easily performed by hardware.

In the present invention, the traveling locus LP 'is rotated to make the road RP'
The sum of the squares of the distance between the head positions of the corresponding line segments in the traveling trajectory LP 'and the road RP' is minimized so that the relative distance between the corresponding line segments is minimized. Traveling locus LP 'with an angle θ
Is rotated.

That is, in this case, in the relationship of FIG.
−p (i−1) = Δpi, qi−q (i−1) = Δqi, li−1
(I-1) = [Delta] li, mi-m (i-1) = [Delta] mi, li'-1
(I−1) ′ = Δli ′, mi′−m (i−1) ′ = Δmi ′
Then, the position correlation corr is obtained according to the following equation (8).

It is.

Thus, from the relationship of equation (8), when θ = −α ′, co
rr becomes the minimum, and the rotation angle θ of the traveling locus LP ′ becomes −
If it is set to be α ′, the correlation corr of the position can be minimized.

Thus, according to the present invention, the traveling locus LP 'and the road RP'
Travel trajectory LP 'and the road so that the relative distance between
RP 'and the traveling locus LP' are rotated at an angle θ such that the sum of the squares of the distances between the respective line segments corresponding to each other is minimized so as to match the road RP '. It becomes possible to perform alignment with emphasis on the direction.

In practice, the most problematic is that the direction of the traveling locus LP is out of order, so that the matching is desirable.

In addition, when the position correlation corr is obtained, according to the equation (7), the calculation is performed using the position on the coordinates of each line segment in the traveling locus LP ′ and the road RP ′, so that the vector of each line segment is obtained. Larger columns require more significant digits for calculations.

On the other hand, if the position correlation corr is obtained by the equation (8), since the relative distance between each line segment on the traveling locus LP 'and the road RP' is used, the effective digit required for the calculation is the equation (7) It is less than the case.

Effects As described above, in the moving object current position display device according to the present invention, the traveling locus pattern is translated in parallel so that the leading current position of the traveling locus is located at the head position of the road in the matched pattern. Then, the traveling locus is rotated by an angle that minimizes the correlation between the position of the traveling locus pattern approximated by the folding line and the matching road pattern by the equal length line segments, and the traveling locus is matched. On the road
The correlation of the positions is obtained by summing the difference between the absolute positions of the respective line segments corresponding to each other in the pattern of the traveling locus and the road pattern, which are approximated by broken lines using equal length line segments, or the sum of the squares of the relative distances between the line segments. This has an excellent advantage that the running locus can be accurately adjusted on the matched road.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a moving body current position display device according to the present invention, FIG. 2 is a diagram showing an example of a display screen in the embodiment, and FIG. FIGS. 4 (a) and 4 (b) show states where the estimated current position is set on the road for each fixed traveling distance of the moving object, respectively. ,
FIG. 5 is a diagram showing a relationship between a current position of a moving body off the road and an estimated current position set on the road, FIG. 6 is a diagram showing an example of a change state of a direction on a traveling locus of the moving body,
FIG. 7 is a view showing a cut-out state of a candidate road pattern to be matched, FIG. 8 (a) is a view showing a state in which a traveling locus pattern of a moving body is approximated by a line segment of equal length, and FIG. FIG. 9B is a diagram showing a state in which a road pattern is approximated by broken lines using equal length line segments. FIG. 9 is a diagram showing a traveling locus such that the current position of the moving object is located at the head position of the matched road. FIG. 10 is a diagram showing a vector sequence of each line segment when translated, and FIG. 10 is a diagram showing a state in which the vector sequence of the traveling trajectory is rotated and adjusted to the road. DESCRIPTION OF SYMBOLS 1 ... Distance sensor, 2 ... Direction sensor, 3 ... Signal processing device, 4 ... Traveling locus storage device, 5 ... Map information storage medium, 6 ... Storage medium reproduction device, 7 ... Display device, 8 ......
Operation device

Claims (4)

(57) [Claims] A current position on a two-dimensional coordinate system, which changes with the traveling of a moving object, is sequentially obtained while detecting a traveling distance and a traveling direction of the moving object, and map data is read from a storage medium in advance. The current position of the moving object is updated and displayed on the screen on which the predetermined road map is displayed, and the data of the current position are sequentially stored and held in the memory. In a current position display device of a moving body, the matching is performed with a road pattern on a map, and the current position of the moving body is corrected by adjusting a traveling locus on the matched road. After translating the traveling locus pattern so that the current position of the beginning of the traveling locus is located at the head position of the road in the taken pattern, and so on. The running locus is rotated at an angle that minimizes the correlation between the position of the running locus pattern approximated by the broken line and the position of the matched road pattern by the line segment, and the running locus is placed on the matched road. Taking the summing means, and taking the sum of the squares of the difference between the absolute positions of the corresponding line segments in the running trajectory pattern and the road pattern, which are approximated by broken lines using equal length line segments, by taking the correlation of the positions. A current position display device for a moving object, characterized in that the current position display device is obtained by: 2. The data obtained by squaring the difference between the absolute position of each corresponding line segment in the travel locus pattern and the road pattern approximated by a broken line using equal length line segments, and assigning a smaller weight to the past data. 3. The current position display device for a moving object according to the above item 1, wherein the sum is calculated. 3. A current position on a two-dimensional coordinate system, which changes with the traveling of the moving object, is sequentially obtained while detecting a traveling distance and a traveling direction of the moving object, and map data is read from a storage medium in advance. The current position of the moving object is updated and displayed on the screen on which the predetermined road map is displayed, and the data of the current position are sequentially stored and held in the memory. In a current position display device of a moving body, the matching is performed with a road pattern on a map, and the current position of the moving body is corrected by adjusting a traveling locus on the matched road. After translating the traveling locus pattern so that the current position of the beginning of the traveling locus is located at the head position of the road in the taken pattern, and so on. The running locus is rotated at an angle that minimizes the correlation between the position of the running locus pattern approximated by the broken line and the position of the matched road pattern by the line segment, and the running locus is placed on the matched road. By taking the means of fitting, by taking the sum of the squares of the relative distances between the corresponding line segments in the running trajectory pattern and the road pattern which are approximated by broken lines using equal length line segments A current position display device for a moving object, wherein the current position is displayed. 4. The sum of squared relative distances between corresponding line segments in a travel trajectory pattern and a road pattern approximated by a broken line by equal-length line segments, but with a smaller weight for the past data, Item 4. The current position display device for a moving object according to the item 3, wherein the current position is displayed.