JP2657549B2 - 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 moving body such as a car in an unguided area or the like, a distance sensor and a direction sensor are provided in order to perform appropriate guidance so that the driver does not get off the scheduled course and lose his way. 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 of a moving body has been developed which enables a driver to confirm a current position by displaying the current position on a map while sequentially updating the point information.

However, with such a moving body current position display device, the occurrence of a position error due to factors such as the accuracy of each sensor of the distance sensor and the direction sensor and the accuracy of calculation using the significant digits at the time of calculating the current position cannot be denied. The error accumulates as the vehicle progresses, and the current position displayed on the screen gradually deviates from the road on the map, making it impossible to determine on which road the vehicle is traveling on the map Problem.

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 data of the current position which is sequentially updated according to the road pattern on the map and the travel of the moving object is performed. A 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. 1-4181).
No. 7).

At this time, if the matching accuracy is set high when the matching of the traveling locus on the road is allowed, the accuracy of the current position of the moving object corrected by the matching is improved, but the position caused by the sensor or the like is improved. If the accuracy of the calculation, the accuracy of the map itself, and the like are not good, the matching set at a high level may not be easily obtained, and the matching may not be performed.

In this case, the current position of the moving object is continuously displayed while being off the road on the map, and the recognition of the current position is impaired.

If the matching accuracy is set low, the probability of matching by matching increases, but the matching accuracy decreases, and the current position of the moving object whose position has been corrected on the road goes out of order. There is a possibility that a situation where the current position cannot be recognized may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and uses the matching of a travel locus to a road on a map by high-precision and low-precision matching together to calculate a current position calculated by an arithmetic process. It is an object of the present invention to provide a current position display device for a mobile body, which can simultaneously satisfy the guarantee of accuracy and the recognizability of the current position displayed on a road map.

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 object obtained by the signal processing device 3, and records and retains the data as finite continuous position information of the moving object. 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 a 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 display mode, such as changing the direction of the display, shifting the display position, partially enlarging the map and travel trajectory, and selecting the display scale. It is constituted by an operating device 8 which 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 traveling of the moving body 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 traveling route display device, in the present invention,
Under the control of the signal processing device 3, when the current position of the moving object and the traveling locus up to that point deviate from the road on the map, as described below, the pattern of each nearby road and the traveling locus of the moving object are determined. Match the pattern
The road on which the pattern is matched is regarded as the currently traveling road, and the current position of the moving object and the display position of the traveling locus are corrected on the road.

At this time, when matching the pattern of the traveling locus of the moving object with the pattern of the road, the candidate of the road to be subjected to the pattern matching is selected as necessary as follows, and the matching process is performed. We try to reduce the burden of.

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 established for all 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 the XY coordinates of each line segment is stored in the map information recording 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, detect 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.

In this case, it is 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 at the current position P of the moving object. .

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, according to the present invention, even when there are many roads near the current position off the road, a candidate for a road having a high probability of being subjected to matching to be subjected to the matching process is selected to a minimum. And the burden of the matching process is effectively reduced.

Further, in the present invention, when matching the traveling locus pattern of the moving object with the pattern of the candidate road, the matching process may be sequentially performed every time the moving object travels a fixed distance and the estimated current position is set. However, since the processing load increases, the direction change amount of the traveling locus of the moving body is constantly monitored, and when the integrated value of the direction change amount becomes larger than a certain value, the shape of the traveling locus changes. It is considered that a large feature has occurred, and at that time, matching processing according to the pattern of the traveling trajectory 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 direction change becomes equal to or greater than a preset value, the matching 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 road pattern 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 body as described above is used as the top, and the previous matching processing point S A road pattern that connects the set points of a plurality of estimated current positions x 'in the past up to is extracted.

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 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).

Further, in the present invention, when matching the extracted pattern of the traveling locus of the moving object with the pattern of the candidate road cut out as described above, the pattern of the traveling locus RP as shown in FIG. Is approximated by a line segment of equal length, and the pattern of the candidate road KP is also approximated by a line segment of equal length as shown in FIG. 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 that is a polygonal approximation under the same conditions, the direction and position of each corresponding line segment can be easily compared. And the matching process can be easily and accurately performed.

The specific matching process is performed as follows.

First, the correlation between the position of the travel locus pattern approximated by a broken line using equal length line segments and the position of the candidate road pattern is determined. At that time, after the pattern of the traveling locus is rotated in a predetermined manner so as to match the directionality of the road pattern, the distance between the head points of the corresponding line segments of the traveling locus pattern and the road pattern is integrated. It is a correlation between positions.

That is, as a first step, a vector sequence obtained by approximating a broken line of a traveling locus is used. And the vector sequence of the candidate roads (| S1 | = | s2 | = ... = | sn | = | r1 | = | r2 | =… =
| rn |), the rotation angle θ of the vector sequence of the traveling locus is calculated according to the following equation.

Here, the accuracy of the current position calculated as ω (i) decreases as the moving body travels. Therefore, when using the data of each vector sequence si, ri, the weight of the past data is set to be smaller for the past data. As described above, the weight function is set in advance according to the sensor accuracy of the distance sensor 1 and the direction sensor 2 and the calculation accuracy when calculating the current position of the moving object.

As a second step, according to the rotation angle θ, the vector sequence of the traveling locus is rotated using the following equation (4).

It should be noted that the direction detection error can be corrected as a result by performing the rotation processing of the vector sequence of the traveling locus.

As a third step, a position correlation value f is obtained according to the following equation according to the road vector sequence of the vector sequence of the rotation trajectory that has been subjected to the rotation processing.

Next, taking into account the distance inspection error in obtaining the current position P of the moving object, the vector sequence of the road obtained by extending the head position x of the candidate road by a fixed distance + δ (several tens of meters) according to the road pattern. In addition, the correlation value f of the position with the vector sequence of the traveling trajectory is obtained in the same manner as described above using a vector example of a road in which the leading position of the candidate road is shortened by a fixed distance -δ according to the road pattern.

Finally, the smallest one of the obtained correlation values f is selected, and when the selected correlation value f is equal to or less than a certain reference value, it is determined that matching has been achieved,
As shown in FIG. 9, the traveling locus RP is translated so that the current position P of the traveling locus is located at the head position (for example, the position of x + δ) of the matched road pattern, and then the traveling locus is moved. Is rotated by an angle θ about the point P to fit on a road where matching has been achieved.

By performing such a matching process, the current position P of the moving object deviating from the road on the map and the position of the traveling trajectory leading to the current position P are corrected.

The present invention is characterized in that when performing the above-described matching processing, the correction of the current position and the traveling locus by matching with different precision is used for calculation and display.

That is, the reference value to be compared with the correlation value f when determining that the pattern of the traveling locus of the moving object and the road pattern on the map have been matched is set to a small value, and the matching accuracy is increased. The position correction at this time is used for calculation, and based on the data of the current position of the moving body whose position has been corrected, the current position accompanying the traveling of the moving body is calculated.

In addition, the reference value is set to a large value, the correction of the current position of the moving object when the matching accuracy is lowered is used for display, and based on the data of the current position and the traveling trajectory of the position-corrected moving object, The current position and the running locus adjusted to the road on the map are displayed.

According to the present invention, when a high matching accuracy is obtained during the matching process, the position correction is performed for both the calculation and the display. However, when only a low matching accuracy is obtained during the matching process, the display correction is performed. Is performed, and the position correction for the calculation is not performed.

The travel locus storage device 4 is provided with a data storage unit for calculation and a data storage unit for display, and based on the respective stored data, a position correction for calculation and a position correction for display are performed. Are performed separately.

Also, when position correction with high matching accuracy is performed, the data in the data storage for calculation is rewritten according to the correction position at that time, and the data in the storage for display is also stored at that time. It will be rewritten to be the same as the data in the department.

Now, for example, as shown in FIG. 10, when the accuracy of the road map is poor and there is a relatively large error in the position of the road R3 among the roads on the map consisting of R1 to R6 (the road on the map)
(The actual road position corresponding to R3 is indicated by the dotted line in the figure), and when the moving body advances to roads R1, R2, and R3, the travel locus in the portion corresponding to road R3 is displaced by the dotted line in the figure. Would be.

In this case, if the matching process matches the running locus at the position indicated by the dotted line in the figure with the road R3 on the map,
When the vehicle travels on the roads R4 and R5 thereafter, the current position and the travel locus may be off the road R5, and may be incorrectly combined with the road R6 in a subsequent matching process.

According to the present invention, in such a case, the accuracy of the matching is set high, and the position correction for the calculation such that the traveling locus located at the position indicated by the dotted line in the figure matches the road R3 on the map can be easily performed. And the accuracy of the current position of the moving body calculated thereafter is guaranteed.

At the same time, in a state where the matching accuracy is set low, the display position correction for adjusting the traveling locus at the position indicated by the dotted line in the figure to the road R3 on the map is performed for convenience, and the movement on the road map is performed. Recognition of the current position of the body is ensured.

Further, according to the present invention, as shown in FIG. 11, when traveling on a wide road having a plurality of lanes, the data of the road on the map is based on the position of the center of the actual road. Since it is registered as
When the moving object A is traveling in the lane at the end of the road, the position is corrected for display so that the traveling locus is adjusted to the road on the map, but the current position is calculated for calculation. In order to maintain the accuracy of (1), such matching is not easily performed.

Further according to the present invention, for example, as shown in FIG.
When the moving object travels on the new road indicated by the dotted line in the figure that is not on the map along the road R1 part, it is convenient for the display to correct the position so that the running locus is adjusted to the road R1 on the map The calculation is performed so as to prevent such a situation that the calculation of the current position is greatly misaligned later.

In the above embodiment, the matching accuracy is high.
The low is determined by the correlation value of the position between the pattern of the traveling trajectory of the moving body and the pattern of the road on the map.
The low level may be determined by a matching ratio based on a matching ratio between the pattern of the traveling locus of the moving object and the pattern of the road on the map.

In this case, all known pattern matching techniques that determine a matching ratio by a predetermined calculation for pattern matching while comparing a pattern to be matched with a reference pattern can be applied.

In this case, the matching rate is set to a higher value of, for example, 90% or more, so that the above-described position correction for calculation is performed.
The above-described position correction for display may be performed by setting a value lower than%.

Effects As described above, in the current position display device for a moving object according to the present invention, a pattern of a traveling locus of the moving object is matched with a road pattern on the map, and the vehicle is driven on the matched road. When correcting the current position of the moving object by adjusting the trajectory, the correction of the current position by the matching process with different precision is used separately for the current position calculation and for the current position display. There is an excellent advantage that it is possible to simultaneously assure the accuracy of the position and to secure the current position displayed on the road map.

[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. 4A and 4B show a state where the estimated current position is set on the road for each fixed distance of the moving object, respectively. Fifth
FIG. 6 is a diagram showing a relationship between a current position of a moving body deviating from a 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. 8A is a diagram showing a cut-out state of a candidate road pattern to be matched, and FIG. 8A is a diagram showing a state in which a traveling locus pattern of a moving object is approximated by broken lines using equal-length lines. b) is a diagram showing a state in which the pattern of the road is approximated by broken lines using equal length line segments, and FIG. 9 is a diagram showing a state in which the current position and the traveling trajectory of the moving object are matched on the matched road. FIG. 10 is a diagram showing an example of a road on a map, FIG. 11 is a diagram showing a state where a moving object is traveling on a wide road having a plurality of lanes, and FIG. 12 is an example of a road on a map. FIG. 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 (5)

(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 locus of the moving body 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. A current position display device of a moving body that matches a road pattern on a map and adjusts the current position of the moving body by adjusting a traveling locus on the matched road, The moving object is characterized in that the correction of the current position is used separately for the current position calculation and the current position display by different matching processes. Standing position display device. 2. A current position display apparatus for a moving object according to claim 1, wherein the adjustment with a high matching accuracy is used for calculating the current position, and the alignment with a low matching accuracy is used for displaying the current position. . 3. The present invention according to claim 2, wherein when only a low matching accuracy is obtained during the matching process, only the matching for displaying the current position is performed. Position display device. 4. The method according to claim 2, wherein a high or low matching accuracy is determined by a correlation value of a position between a pattern of a traveling locus of the moving object and a pattern of a road on a map. The current position display device of the moving body according to the description. 5. The method according to claim 2, wherein the high and low matching accuracy is determined by a matching rate based on a rate of coincidence between a pattern of a traveling locus of the moving object and a pattern of a road on a map. The current position display device of the moving body according to the description.