JPH0450718A - Mobile object current position display device - Google Patents

Abstract

PURPOSE:To display the current position of the moving body with high accuracy at all times by correcting the current position of the moving body according to a measured position obtained by a self-contained inertial navigation system when the current position of the moving body found by self-inertial navigation is displayed. CONSTITUTION:The current position of the moving body which is found by the self-contained inertial navigation system is basically displayed 8 on a screen. Namely, when the current position of the moving body and its travel locus obtained so far deviate from a road on a map, a signal processing part 4 regards a road, where patters of respective circumferential roads and the pattern of the travel locus of the moving body are matched since the similarity between both the patterns is larger than a preset value, as the road where the moving body travels currently. The travel locus is put on the road and the current position of the moving body and the display position f the travel locus are corrected. Thus, the current position can be displayed with high accuracy.

Description

[Detailed Description of the Invention] [Technique] Mata - The present invention is a method for detecting the current position of a moving body and displaying the current position of the moving body on a road map displayed on a screen in advance. Related to display devices.

Genkei TakesueRecently, in order to provide driving guidance for moving objects such as cars, while detecting the current position that changes every moment as the moving object moves, a road map of the area where the moving object is scheduled to be driven is displayed on the screen in advance. A current position display device for a moving object has been developed which updates and displays the current position of the moving object using point information.

Conventionally, this type of current position display device for a moving object detects the travel distance and direction of movement of the moving object using a distance sensor and a direction sensor mounted on the moving object.
One is based on independent inertial navigation, which cumulatively determines the current position on the X-Y coordinates through sequential calculations, and the other is the position on the coordinates set by a transmitter installed at a reference point such as an artificial satellite or a signpost on the ground. It is measured while receiving the transmitted radio waves by a receiving device mounted on a mobile object.

In the former case, which is based on independent inertial navigation, it is unavoidable that position errors occur due to factors such as the accuracy of the distance sensor and direction sensor and the calculation accuracy of significant digits when calculating the current position, and as the moving object progresses, The problem is that as the errors accumulate, the current position displayed on the screen gradually deviates from the road on the map, making it impossible to determine which road on the map your army is traveling on. There is.

Therefore, in the past, in order to correct the current position that deviates from the road on the map, the travel obtained by storing and retaining the data of the current position that is updated sequentially according to the road pattern on the map and the movement of the mobile object. The current position of the moving body is corrected by performing matching processing with the pattern of the trajectory and matching the traveling trajectory onto the matched road (see Japanese Patent Laid-Open No. 1-41817).

However, if such a matching method is used, if there are parallel roads nearby or if a travel trajectory that is long enough to match the final pattern is not obtained during the initial travel, The matching accuracy decreases, and matching cannot be performed when the moving object is traveling on a road that is not on the map.

Furthermore, if the roads are complex, the number of roads subject to matching processing increases, which increases the processing load, which may cause problems with processing performance, such as the time required for matching processing. It has become.

In this respect, the latter method using radio navigation such as GPS,
The current position of a moving object can be directly measured each time, and position errors do not accumulate.

However, the measured position includes an error of about several tens to 100 meters, and if there are multiple roads within the error range, it becomes impossible to determine which road the vehicle is traveling on.

For this reason, in the past, GPS and self-contained inertial navigation were used to detect the current position of a moving object, in order to increase the reliability of GPS positioning, and when a GPS positioning signal could not be obtained, the movement vector determined by self-contained inertial navigation was used. Or, GPS positioning data is incorporated as a correction scale for the position calculated by independent inertial navigation (see Japanese Patent Application Laid-Open No. 61-1.37009 and Japanese Patent Application Laid-Open No. 155813-1983). .

However, G
In PS as well, S A (Selective
Availability) has been introduced,
The positional accuracy deteriorates, and the actual situation is that it becomes a burden to calculate the current position, causing delays in calculation processing and problems with matching with road maps.

The present invention was made in consideration of the above points, and the current position of a moving object determined by independent inertial navigation is corrected by matching each pattern between the travel trajectory and the road on the map, and is displayed on the screen. When displaying on a road map that has been copied to a map, when the matching accuracy decreases or it becomes impossible to perform matching, the position is determined by independent inertial navigation based on the position measured by radio navigation such as APS. To provide a current position display device for a moving body which can always display the current position with high accuracy mainly using self-contained inertial navigation by correcting the current position of the moving body.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 shows an example of the configuration of a current position display device for a moving object according to the present invention, which includes a speed sensor 1 that detects the traveling speed of a moving object, and a speed sensor 1 that detects the angular velocity of a change in one direction, for example, of a moving object. An antenna ANT transmits radio waves emitted from a rate type direction sensor 2 that outputs a signal proportional to the amount of change in direction as the vehicle travels, and a transmitter (not shown) installed at a reference point such as an artificial satellite or a signpost on the ground. The traveling distance of the moving object is measured by time-integrating the traveling speed detected by the receiver 3 and the speed sensor 1, and the moving distance is measured by time-integrating the angular velocity detected by the direction sensor 2. While calculating the amount of change in the moving direction of the body, the current position on the X-Y coordinates for each unit distance traveled by the moving body is determined by sequential calculations using independent inertial navigation, and also by radio navigation such as GPS according to the received radio waves. A signal processing unit 4 consisting of a microcomputer that measures the current position of the moving object on the same coordinates and centrally controls the entire device, and sequentially stores data on the current position of the moving object determined by autonomous inertial navigation. and a travel trajectory storage unit 5 that stores and holds the finite continuous position information of the moving object, and a map in which information of a plurality of road maps is stored in advance with position data on the X-Y coordinates of each road. An information storage medium 6, a storage medium playback unit 7 that selectively reads out road map information from the storage medium 6, and displays a predetermined road map on a screen based on the read map information, and displays the screen. a display section 8 that displays the current position of the moving object on a road map projected on the road map along with the traveling trajectory and the traveling direction of the moving object at the current position as necessary, and a signal processing section; 4, selects and designates a map to be displayed on the display section 8, sets the starting point of the mobile object on the displayed map, and selectively gives commands to display the traveling trajectory, etc. to 1. An operation unit 9 that can appropriately change the display format settings, such as changing the direction of the displayed map and travel trajectory, shifting the display position, and selecting a partial enlarged display 2 of the map and travel trajectory, display scale ratio, etc. It is composed of.

Here, the method of calculating the current position of the moving body using autonomous inertial navigation is exactly the same as the conventional method, and the method of measuring the position using radio navigation is a known method such as GPS, which is directly applied.

With this configuration, the present invention basically displays on the screen the current position of the moving body determined by independent inertial navigation.

That is, the map read from the map information storage medium 6 is displayed on the screen of the display section 8, and the signal processing section 4 presets the map according to the traveling of the mobile object from the starting point set on the map. The current position on the X-Y coordinates is calculated moment by moment according to the scale of the map, and the calculation results are sequentially sent to the travel trajectory storage section 5 to update its memory contents. The contents are constantly read and sent to the display section 8.

Thereby, as shown in FIG. 2, the display unit 8 displays a display mark Ml indicating the current position of the mobile object on the map displayed on the screen, and a display mark Ml indicating the traveling direction of the mobile object at the current position. The display mark M2 and the display mark M3 of the traveling trajectory from the starting point ST to the current position are displayed in a simulated manner following the traveling state of the moving body.

In displaying the current position of a moving object using independent inertial navigation as shown in Figure 3, due to the cumulative error mentioned above, the current position and traveling trajectory may change from the road on the map as the moving object progresses. Gradually, they become deviated from each other, and eventually it becomes impossible to determine where on the map their own troops are currently traveling.

Therefore, in the present invention, when the current position of the moving object and the travel trajectory up to that point deviate from the road on the map, the signal processing unit 4 uses the pattern of each road in the vicinity and the moving object's current position as described below. If the similarity with the pattern of the driving trajectory is greater than a preset value, the two patterns are matched, and the road on which the matching is performed is regarded as the road on which the driver is currently driving, and the driving trajectory is placed on that road. In conjunction with this, the current position of the moving object and the display position of the traveling trajectory are corrected.

At that time, when matching the travel trajectory pattern with the road pattern, for example, a road along the travel trajectory of the moving object or a road within a certain distance range from the current position of the moving object, etc. Roads that have a certain correlation with the current location are extracted as road candidates to be matched, thereby reducing the burden of the matching process.

A specific example of extraction of candidate roads will be explained below.

First, a fixed travel distance 1 of the moving object: Therefore, the estimated current position of the moving object is set on the road on which it is currently traveling on the map and on all roads branching from that road.

At that time, as shown in Fig. 4(a), if there is no branch road within a certain distance from the set point of the previous estimated current position Therefore, the estimated current position lx is set at a position further advanced by a certain distance. Further, as shown in FIG. 4(b), if there is a branch road within the certain distance, the estimated current position xi, x2 . Set x3 respectively. Here, the relationship is Q1+Q2=Q1+Q3=QI+Q4=L.

In addition, according to the estimated current position setting 1, each time it is detected that the moving object has traveled a certain distance, signal processing is performed according to the road position data on the map displayed on the screen of the display unit 8 at that time. automatically under the control of section 4. The setting of the estimated current position may be performed by sequentially setting the estimated current position every predetermined time period as the moving object travels, without depending on the distance traveled by the moving object. It is also conceivable to make the setting interval of the estimated current position variable depending on the traveling situation of the mobile object.

Each road is divided into lines, and position data on the X-Y coordinates of each line segment is stored in the map information storage medium 6.

Next, it is determined whether the distance between the estimated current position set as described above and the current position of the moving object calculated at that time and displayed off the road is within a predetermined tolerance range. Then, the estimated current position within the range is selected, and only the roads on which the selected estimated current position exists are candidates for matching.

For example, given the relationship shown in Figure 5, the estimated current position flx
The distance between (xi, x2.x3) and the current position P is D
(Di, D2.D3), select the estimated current position that satisfies the following equation % (1).

Here, M is a preset tolerance range, for example, 5
It is set to about 0m. α is a coefficient related 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%. Also, for L, it is 100
It is set to about m.

In this case, it is also conceivable to select an estimated current position set on a road whose direction is within a certain allowable angular difference with respect to the traveling direction at the current position P of the moving object. .

Therefore, in the relationship shown in Fig. 5, if the value of M is set relatively small, only x2, for example, is selected as the estimated current position that satisfies the condition of equation (1), and the estimated current position x2 exists. The roads that match are selected as candidate roads to be subjected to matching processing.

Therefore, even if there are many roads near the current location that are off the road, it is possible to select the minimum number of road candidates that have a high probability of being matched. This effectively reduces the burden of matching processing.

Furthermore, when matching the travel trajectory pattern of a moving object with the candidate road pattern, the processing load is large if the matching process is performed sequentially every time the moving object has traveled a certain distance and the estimated current position is set. Therefore, we constantly monitor the amount of change in direction of the traveling trajectory of a moving object, and when the value that integrates the amount of change in direction becomes larger than a certain value, it is considered that a major characteristic has occurred in the shape of the traveling trajectory. At that time, a matching process is executed at once according to the pattern of the traveling trajectory of the moving object during the previous integration period.

That is, as shown in FIG. 6, for each fixed travel distance Q of the moving body, the angle w i (i = Ot 1 +2
．． 3. ), and the integrated value W of the amount of direction change is calculated sequentially according to the following equation.

w =, l l w, -w-1 (n=1.2, 3.-
1- (2) When the calculated total amount W of direction changes exceeds a preset value, the starting point a (becomes the previous matching processing point) from the current position IP of the moving object at that time The travel trajectory up to that point is selected as the target of the current matching process.

Therefore, if the matching with the road is performed according to the traveling trajectory of the moving object that has significant characteristics in the pattern, the number of matching processes will be reduced overall, and the accuracy will be improved according to the characteristics of the pattern. It becomes possible to perform matching processing with high efficiency.

At this time, the road pattern to be matched is, for example, as shown in FIG. 7, starting from the estimated current position A road pattern that connects a plurality of set points of past estimated current positions @X up to S is plotted.

Note that when cutting out a road pattern with multiple estimated current positions and performing the matching process at once, each estimated current position that satisfies the relationship in equation (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 becomes farther away as the moving object progresses, so as the moving object progresses (1 ) It is necessary to increase the value of M in the equation.

When matching the pattern of the traveling trajectory of the mobile object thus marked with the pattern of the candidate road marked as described above, for example, as shown in FIG. 8(a), the traveling trajectory LP The pattern of the candidate road RP is similarly approximated as a broken line by line segments of equal length as shown in FIG. Matching is performed using the vector sequence of each line segment.

If we perform matching using each pattern that approximates the traveling trajectory of a moving object and a road on a map under the same conditions as broken lines, we can compare the direction and position of each corresponding line segment. This makes it possible to easily perform the matching process with high precision.

The specific matching process is performed as follows.

As a method for determining the similarity between a travel trajectory pattern and a candidate road pattern, first, the correlation between the positions of the travel trajectory pattern and the candidate road pattern, each of which is approximated by a broken line using line segments of equal length, is determined. .

At that time, the travel trajectory pattern is rotated in a predetermined manner to match the directionality of the road pattern, and then the distance between the head points of each corresponding line segment between the travel trajectory pattern and the road pattern is integrated. Let it be a correlation of position.

That is, as a first step, the vector sequence obtained by the broken line approximation of the traveling trajectory is expressed as (sl, s2.$3+... an)
Then, the slip torque sequence approximated by the broken line of the candidate road is (r 1
+ T2,731 ・”+ yn) When (lsl
=1s21=...=5nl=lrl=l r
21 =-= l rnl ), the rotation angle θ of the vector sequence of the travel trajectory is determined according to the following equation.

θ=Teω(i)・cos−1(si・ri/l si
l Hl ril)×l/Σω(i) ・
...(3) Here, ω(1) is a weighting function.

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

Note that by performing such rotation processing on the vector sequence of the travel trajectory, it is possible to correct the direction detection error as a result.

As a third step, a positional correlation value f is determined according to the following equation according to the vector sequence of the rotationally processed traveling trajectory and the vector sequence of the road.

Next, taking into account the distance detection error when determining the current position P of the moving object, the top position of the candidate road [X
Driving in the same way as above with a road vector sequence that is extended by a certain distance + δ (several tens of meters) according to the road pattern, and a road vector sequence that is shortened from the starting position of the candidate road by a certain distance - δ according to the road pattern. The correlation value f of the position with the vector sequence of the trajectory is determined.

Finally, if the similarity between the travel trajectory pattern and the candidate road pattern is greater than or equal to a preset value, one way to determine that the two patterns are matched is to use the correlation values determined for each. The smallest correlation value f is selected, and matching is determined when the selected correlation value f is less than or equal to a reference value.

Then, as shown in FIG. 9, the traveling trajectory LP is translated in parallel so that the current position 11P of the traveling trajectory is at the leading position of the matched road pattern (for example, the position if X+δ), and then The traveling locus is rotated by an angle θ around point P to fit it onto the matched road.

By performing such matching processing, the display position of the current position P of the moving object that has deviated from the road on the map and the travel trajectory up to that position is corrected.

At this time, each position X+δ is added or subtracted by a certain distance δ from the estimated current position lIx on the candidate road.

Divide the area between If it is determined that matching has been performed when the value is less than or equal to the value, matching accuracy can be further improved.

It goes without saying that such matching processing may be executed periodically.

In particular, in the present invention, such a current position display device for a moving object can be used, for example, when the moving object is traveling on a road that is not on the map and cannot be matched, or as shown in FIG. As shown in FIG. 11, when roads with similar shapes are close to each other in parallel, and there are multiple roads with similarities greater than or equal to -, and it is unclear which road to match, Alternatively, in the case where matching cannot be performed because a traveling trajectory of sufficient length to match the last pattern cannot be obtained during the initial running, the signal processing unit 4 determines that such a case has occurred. However, at that time, the current position of the moving body by autonomous inertial navigation is temporarily corrected so that it is at the position measured by radio navigation such as GPS.

At that time, the signal processing section 4 is operated as shown in FIG. 12(a).

As shown in (b), the current position P of the moving body is temporarily corrected so that it comes to the position G measured by radio navigation, and the travel trajectory LP is translated in parallel.

If there is no past corrected position at the time of the previous matching process (corrected position by matching or corrected position by radio navigation), the signal processing unit 4 determines that the traveling trajectory LP remains in parallel movement. In the modified state, the current position data and traveling trajectory data are rewritten.

Note that the signal processing unit 4 executes data processing for coordinate transformation such that a position on the measured coordinates by radio navigation becomes a position on the XY coordinates by autonomous inertial navigation.

In this way, during the matching process, if matching cannot be achieved or the road to be matched cannot be specified, the current position P of the moving object is corrected to the position G measured by radio navigation, and the traveling trajectory LP is changed. By performing the parallel movement, a rough correction is made, and matching becomes easier in the next matching process.

In addition, the signal processing unit 4 is configured as shown in FIGS.
As shown in , when the travel trajectory LP is translated in parallel, if there is a past corrected position G' at the time of the previous matching process, the travel trajectory LP that has been translated in parallel is changed to the current position P that has been corrected to the G position. Use it as a fulcrum and rotate it to the G' position.

Then, the signal processing unit 4 rewrites the current position data and the traveling locus data in the corrected state in 1).

Therefore, such a traveling trajectory LP can be changed to the past correction position 1 [
By rotating the vehicle up to G', the traveling trajectory LP can be precisely corrected, and matching becomes easier in the first matching process.

At that time, the current position of the moving object being inspected using autonomous inertial navigation is corrected by matching it with the road on the map, thereby clearing the cumulative error of the detection data up to that point, so that it is not measured using radio navigation. In particular, the past correction position 1fG' is considered to be more accurate than the previous position.
is the position corrected by matching the traveling locus pattern of the moving object with the road pattern on the road map.

Furthermore, when the travel trajectory LP is rotated to the past corrected position G', the signal processing unit 4 determines whether or not the travel trajectory LP matches the road on the map based on the data of the travel trajectory and the road data. If they match (see FIG. 13, C), it is assumed that matching has been achieved by correcting the current position P and travel trajectory LP.

Furthermore, if the travel trajectory LP does not match the road on the map, the current position P and the travel trajectory LP are temporarily corrected, and then matching processing is performed.

Note that when the current position WLP of the moving object is corrected.

As described below, provisional corrections may be made directly according to the position determined by radio navigation.

That is, in this case, FIG. 14(a).

As shown in (b), the position W measured by radio navigation is determined in advance by considering the error range of G.
A road that extracts roads on a map within a predetermined distance range defined by a circle with radius a centered on IG, and the distance between the extracted road and the current position P of the moving object is the minimum value L min. Correct so that the current position P is at the upper position P'.

Then, the signal processing unit 4 processes the extracted digit 1 on the road! P
When correcting the current position IP so that it comes to ', the travel trajectory LP is translated in parallel, and then the travel trajectory LP is rotated using the corrected current position 1iP as a fulcrum, and the travel trajectory LP is
to align the current position P with the corrected road.

At that time, the travel trajectory L is within a predetermined angle range set in advance.
A restriction may be added to allow rotation of P.

The signal processing unit 4 rewrites the data of the current position of the moving body and the data of the travel trajectory in the modified state.

Such a process of correcting the current position and traveling trajectory of the moving object is performed periodically, for example, every time the moving object travels a certain distance.

As described above, according to the present invention, simply displaying the current position of a moving body determined by autonomous inertial navigation or the position measured by radio navigation would result in a position error, but by comparing the positions of both, Based on the position measured by radio navigation, the current position of a moving body can be easily and highly accurately corrected, taking into account the error range of the measured position.

At this time, in particular, since a pattern matching processing means is used, the processing load on the signal processing unit 4 is lightened, and the process of correcting the current position of the moving body can be performed quickly and with good responsiveness. become.

Furthermore, according to the present invention, it is possible to specify the road on the map on which the current position of the moving object is to be corrected, so it is possible to identify roads on the map where the current position of the moving object is to be corrected. Even if the road is complicated, the current position and travel trajectory of a moving object can be appropriately displayed on that particular road.

Furthermore, according to the present invention, the current position of a moving object is determined in detail as the moving object moves by autonomous inertial navigation, and the current position of the moving object is precisely displayed on a road map, while the current position of the moving object is precisely determined by radio navigation. The current position and traveling locus can be efficiently corrected without placing an excessive burden on the signal processing unit 4 by measuring the position coarsely as the moving body travels.

Unfortunately, in the current position display device for a moving object according to the present invention, the current position of the moving object determined by independent inertial navigation is corrected by matching each pattern between the travel trajectory and the road on the map. When displaying on a road map displayed on a screen, when the matching accuracy decreases due to complicated roads, or when matching is not possible due to driving off the road, etc., measurements can be taken using radio navigation. The current position of the moving body is corrected based on the position determined, and has the excellent advantage that the current position can always be displayed with high precision.

In addition, the present invention roughly matches each pattern of driving behavior and roads on a map, centering on the current position of a moving object cumulatively determined by autonomous inertial navigation and the position measured by radio wave drag method. Because we are taking measures to process the
It has the excellent advantage that the position can be easily and quickly corrected, and the current position can always be displayed with high precision on the road map displayed on one screen.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing an embodiment of a current position display device for a moving object according to the present invention, FIG. 2 is a diagram showing an example of a display screen in the same embodiment, and FIG. 3 shows the current position of a moving object. Figures 4(a) and 4(b) are diagrams showing a state in which the vehicle is displayed off the road, and Figures 4(a) and 4(b) are diagrams each showing a state in which the estimated current position of the moving object is set on the road for each fixed travel distance. ,
FIG. 5 is a diagram showing the relationship between the current position of a mobile object that has deviated from the road and the estimated current position set on the road, and FIG. 6 is a diagram showing an example of a state of change in direction in the travel trajectory of the mobile object.
Fig. 7 is a diagram showing how candidate road patterns to be matched are cut out, Fig. 8 (,) is a diagram showing a state in which the travel locus pattern of a moving object is approximated by line segments of equal length; Figure (b) shows a state in which the road pattern is approximated by line segments of equal length, and Figure 9 shows a state in which the current position and travel trajectory of a moving object are matched to the matched road. Figure 10 shows the current position display state when a moving object is traveling on a road that is not on the map, and Figure 11 shows the current position display state when roads with similar shapes are close to each other in parallel. Diagram showing the position display state, Fig. 12(a)
, (b) is a diagram showing an example of the process of correcting the current position of a moving object to the position measured by radio navigation, and FIGS. Figures 14(a) and 14(b), which show other examples of the process of correcting the position measured by radio navigation, show how the current position of a moving object is corrected to a predetermined position centered on the position measured by radio navigation. It is a figure which shows the process of correcting to the latest position of the road on the map within a distance range.

Claims (4)

[Claims] 1. While detecting the traveling distance and direction of the moving object, the current position on the coordinates that change every moment as the moving object moves is calculated sequentially, and the map data is read out from the storage medium in advance and a predetermined road map is created. The current position of the moving object is updated and displayed on the projected screen, and the current position data is stored in memory to obtain the pattern of the moving trajectory of the moving object and the road pattern on the road map. Matches both patterns based on whether the similarity of the two patterns is greater than a preset value, and corrects the current position of a moving object that has deviated from the road on the map by aligning the travel trajectory with the matched road. In a device for displaying the current position of a moving object,
means for detecting the position of the moving object on the coordinates by radio navigation; 1. A current position display device for a moving object, characterized in that the current position display device includes means for correcting the current position. 2. 2. The current position display device for a moving body according to item 1, characterized in that when correcting the current position of the moving body to a position detected by radio navigation, the travel trajectory is translated in parallel. 3. The current state of the moving object according to item 2 above, characterized in that the traveling trajectory is rotated to the past corrected position using the current position of the moving object that has been corrected to the position detected by radio navigation as a fulcrum. Position display device. 4. The mobile object according to item 3 above, wherein the past corrected position is a position corrected by matching the travel trajectory pattern of the mobile object with a road pattern on a road map. Current position display device.