JPH07286856A - Current location calculating device - Google Patents

Abstract

PURPOSE:To provide a current location calculating device which can find the current location of a vehicle without using any azimuth detecting means even when GPS signals are not receivable. CONSTITUTION:The current location calculating device is provided with a vehicle speed sensor 203 which detects the speed of its own vehicle by outputting pulses proportionally to the rotation of the output shaft of the transmission of the vehicle a GPS receiver 205 which outputs the location of the vehicle by processing GPS signals, and a controller 210 provided with a CPU and memory and, when the GPS signals are not receivable, finds the running distance of the vehicle from the location which is confirmed based on received GPS signals by integrating the output of the sensor 203 and obtains the location of the vehicle by measuring the distance along the roads which have been passed by the vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current position calculating device which is mounted on a moving body such as a vehicle and calculates the current position of the vehicle.

[0002]

2. Description of the Related Art A vehicle current position calculating device is, for example, a GP as disclosed in Japanese Patent Publication No. 5-7642.
There is a system that calculates the current position of a vehicle by using a radio navigation system using an S receiver and a dead reckoning system using a gyro and a vehicle speed sensor in combination.
In such an example, the current position of the vehicle is determined based on the position output by the GPS receiver and the position output by the dead reckoning system, and the position is overlaid on the map displayed on the display. The current position of the vehicle is notified to the driver by displaying it.

[0003]

However, in the above-mentioned conventional example, it is necessary to include both the GPS receiver and the dead reckoning system, and the whole system becomes expensive.

In particular, the geomagnetic sensor or the gyro sensor used for detecting the direction required for the dead reckoning system is not only very expensive as compared with the vehicle speed sensor, but also easily affected by the surrounding environment. Therefore, it is difficult to maintain accuracy.

The present invention has been made in order to solve such a problem, and an object thereof is to obtain the position of a vehicle without using an azimuth detecting means even when a radio signal cannot be received. It is to provide a possible current position calculation device.

[0006]

The above object is to provide a current position calculating device equipped with a first position calculating means which is mounted on a vehicle and which calculates a current position of the vehicle by receiving a radio signal. A road data reading means for receiving a storage medium storing data and reading road data around the calculated current position, a speed detecting means attached to the vehicle for detecting the vehicle speed, and the radio signal. If is not received, add up the detected vehicle speed,
A travel distance calculating means for calculating a travel distance of the vehicle from the time when the current position of the vehicle was last calculated by the first position calculating means, and a last distance by the first position calculating means if the radio signal is not received. Second position calculating means for calculating the current position of the vehicle by referring to road data near the current position based on the calculated current position and the traveling distance from the time when the position is calculated to the present time. It is possible to achieve by the present position calculation device which is characterized by having.

[0007]

According to the present invention, in the current position calculating device having the first position calculating means for calculating the current position of the vehicle using the radio signal, when the radio signal cannot be received, the second position calculating means Based on the latest current position calculated last by the position calculating unit 1 and the traveling distance of the vehicle from the time when the position was obtained to the present time, the road data near the position is further referred to. Then, the current position of the vehicle is calculated.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present position calculating device to which the present invention is applied will be described.

The hardware of this embodiment is, for example, as shown in FIG.
It has a configuration as shown in. That is, in the present embodiment, the vehicle speed sensor 203 that detects the vehicle speed by outputting pulses in proportion to the rotation of the output shaft of the vehicle transmission.
And an antenna 2 for receiving GPS signals from GPS satellites
04 and a GPS receiver 20 for processing the GPS signal received by the antenna 204 and outputting the position and direction of the vehicle.
5 and.

The present embodiment further includes a switch 20 that receives a scale switching command of the displayed map from the user.
6 and a CD-RO for storing digital map data
It has an M207, a driver 208 for reading the CD-ROM 207, and a display 209 for displaying a map around the current position and a mark indicating the current position.

The present embodiment further includes a controller 210 for controlling the operation of each peripheral device described above.
The controller 210 includes a counter 21 that counts the number of pulses output from the vehicle speed sensor 203 every predetermined number of seconds.
7, a serial interface 218 that receives data from the GPS receiver 205, a parallel I / O 212 that recognizes the pressing of the switch 206, and a CD-ROM 20.
DMA (Direc that transfers the map data read from 7
t Memory Access) controller 213 and a display processor 214 for displaying a map image on the display 209.

The controller 210 further includes a microprocessor 215 and a memory 216. The microprocessor 215 receives signals from the peripheral sensors and devices obtained through the above-mentioned units, performs processing based on those signals, calculates the current position of the vehicle, and displays the current position via the display processor 214. Day Play 209
To display. This display of the vehicle position is superimposed on the already displayed map, and the user can know the current position of the vehicle on the map.

The memory 216 includes a ROM in which the contents of the processing described below are stored, and a microprocessor 21.
5 has a RAM used when processing is performed.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. This process is started every time the vehicle travels 10 m.

First, the signal from the vehicle speed sensor 203 is read (step 520), and the read values are integrated to be converted into a travel distance (step 521).

Next, it is judged whether or not the GPS signal is received (step 522), and if it is received (Yes in step 522), the GPS receiving device 205 outputs it.
The current position (A) of the vehicle and the traveling direction of the vehicle are read (step 523).

Next, a map around the current position (A) is displayed as C
The data is read from the D-ROM 207 and road data (line segment data) within a predetermined distance D centering on the current position (A) is extracted (step 524). Here, the distance D may be a constant value, or may be a value determined based on an error cost value, which will be described later, obtained last time.

The reason for determining the search range based on the error cost is that it is considered that the reliability of the position accuracy is low when the error cost is large, and it is better to search a wider range and search for the road. Because it makes sense. The road data is, as shown in FIG.
Each road on the map is approximated by a plurality of line segments, and the coordinates of the start point and the end point of each line segment are stored.

Next, from the line segment extracted in step 524, the azimuth in the direction of the line segment and the GPS receiver 2
The line segment whose error with the traveling direction of the vehicle obtained in 05 is within a predetermined value is extracted (step 525). Furthermore, for all the extracted line segments, the current position (A)
Down the vertical line from the line and obtain the length of the vertical line (step 526).

Next, using the lengths of the perpendiculars, the error cost values defined below are calculated for all the line segments extracted in step 525.

Error cost = α × | travel azimuth−line segment azimuth | + β × | perpendicular line length | (1) where α and β are weighting factors. These coefficients can be changed depending on the specific processing method used. For example, when importance is attached to a road having a small error in the traveling direction, α may be increased.

Next, of the line segments for which the error cost has been calculated, the line segment having the smallest error cost value is selected (step 527), and the point at which the selected line segment intersects with the vertical line (the vertical line of the line segment). This is set as the corrected current position (B) (step 528), and this processing ends.

If no GPS signal is received at step 522 (No at 522), it is determined whether or not there is an intersection near the current position (B) (step 53).
1). If there is an intersection nearby (N at step 531)
In o), it is difficult to determine which road the vehicle has taken. Therefore, a non-display signal for outputting the current position of the vehicle is output (step 533),
This process ends.

Here, an example of a method of determining whether an intersection is near is shown below. That is, CD-ROM
In 207, road data as shown in FIG. 6 is stored in the format as shown in FIG. 7 as coordinate information data and intersection information data. Therefore, by examining the intersection information data shown in FIG. 7, it is possible to determine whether or not there is an intersection within the predetermined distance F from the previously calculated current position.

If there is no intersection nearby (step 531)
Yes), the current position (B) obtained last time is used as a reference, and the current position is moved along the road data by a distance corresponding to the distance traveled from the current position (B). ) Is calculated (step 532).

For example, consider a case where the road data corresponding to the road on which the vehicle is traveling is as shown in FIG. Here, the road between a and e is the road segment ab and the road segment b.
c, a road segment cd, and a road segment de. Here, during the road segment ab, the previous GP
It is assumed that there is a current position (B) obtained based on the S signal, and the distance traveled from the time when the position (B) was calculated to now is 100 m.

In this embodiment, in this case, the road segment ab is 30 m, the road segment bc is 60 m, and the road segment c is
The position (point C) when traveling 10 m on d is 100 m from position (B), so point C is set as the current position. Here, the traveling distance is obtained from the vehicle speed sensor 203, and the length of each road line segment can be obtained from the coordinates of the start point and the end point of each line segment. The coordinates of the start point and the end point are read from the coordinate information data shown in FIG.

Next, the process of displaying the current position of the vehicle on the map according to the result obtained by the flow of FIG. 4 will be described with reference to FIG. This processing is started, for example, every one second, and if the current position (B) or the current position (C) is obtained as the current position of the vehicle, it is displayed. Further, if the current position (C) is not calculated and the non-display signal is output, the display is performed in such a form that the user knows that the current position is unknown.

First, the parallel I / O 212 is used to check whether or not the switch 206 is pressed to instruct to change the map scale.
The content is judged by judging (step 601). If it is pressed (Yes in step 601), the predetermined scale flag is switched correspondingly (step 60).
2). Although there are other functions of the switch 206, they are not described because they are irrelevant to the operation of this embodiment.

Next, the latest present position (B) obtained from the GPS signal is read out (step 603), and a map of a scale corresponding to the contents of the scale flag switched in step 602 is displayed. 209
, For example, in the state as shown in FIG. 2 (step 604).

Next, it is checked whether a non-display signal is output (step 605). If the signal is output (Yes in step 605), since the position of the vehicle at that time is unknown, it is displayed in a form that can be recognized by the user (step 608).

Specifically, for example, the last obtained,
The past current position (B), which is surely known, is displayed using a color different from that of the current position display described below. Further, instead of changing the color, the form may be changed or the position may not be displayed at all. Further, it may be configured to display a text message or to indicate a state in which the current position is not calculated by blinking light, sound, or the like.

When the non-display signal is not output (No in step 605), the current position is the current position (B) by the GPS signal (FIG. 4, step 528) or the current position (C) (FIG. 4). , Step 532) is required.

Therefore, in the next step 606, when the current position (B) of the vehicle is obtained, the position (B) and the traveling direction (GPS direction) of the vehicle are, for example,
Display is performed using an arrow symbol "↑" in a predetermined color shown in FIG. If the current position (C) is required, the position (C) is displayed in the same form as the current position (B) or in a different form.

Finally, the north mark indicating north and the distance mark corresponding to the reduced scale are superposed and displayed in an overlapping manner as shown in FIG. 2 (step 607).

According to the present embodiment, when the GPS signal cannot be received by using the GPS receiving device, the vehicle speed sensor, and the road data, the traveling distance from the position where the GPS signal is received last is calculated by the vehicle speed sensor. G is obtained by accumulating the outputs and advancing that distance along the road.
The position of the vehicle can be displayed even if no PS signal is received.

In the present embodiment, the vehicle position and direction are indicated by using the arrow symbols as described above, but the display form of the vehicle position and direction in the present invention is clearly shown in the display state. If it exists, its form and color do not matter. Also, the map display form such as the north mark is not limited as long as it clearly shows the surrounding state.

In this embodiment, the non-display signal is output when the current position of the vehicle cannot be calculated.
The present invention is not limited to this. For example, instead of outputting this signal, a configuration may be adopted in which the state in which the current position of the vehicle is not updated is detected in each processing cycle of FIG. 4 and the display form is selected based on the result.

In this embodiment, if there is an intersection,
Although the current position (C) of the vehicle could not be obtained, for example, if the configuration is such that a change in the direction of the vehicle at the intersection is detected or input, the current position of the vehicle is detected based on that information even if the intersection exists. The position (C) can be determined. For example, by inputting the direction change of the vehicle by the voice of the user,
The configuration may be such that the position (C) of the vehicle is calculated based on that.

[0040]

As described above, according to the present invention, it is possible to provide a current position calculating device which can obtain the position of a vehicle without using a direction detecting means even when a GPS signal cannot be received.

[0041]

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a current position calculation device according to the present invention.

FIG. 2 is an explanatory diagram showing an example of a display form of the current position in the present invention.

FIG. 3 is an explanatory diagram for explaining a position calculation process when a GPS signal cannot be received according to the present invention.

FIG. 4 is a flowchart showing an example of current position calculation processing according to the present invention.

FIG. 5 is a flowchart showing an example of processing for displaying the current position in the present invention.

FIG. 6 is an explanatory diagram showing an example of line segments in road data according to the present invention.

FIG. 7 is a chart showing an example of a storage format of map road data in the present invention.

[Explanation of symbols]

203 ... Vehicle speed sensor, 204 ... Antenna, 205 ... GP
S receiver, 206 ... Switch, 207 ... CD-RO
M, 208 ... CD-ROM driver, 209 ... Display, 210 ... Controller.

Claims (5)

[Claims] 1. A current position calculation device equipped with a first position calculation means for calculating the current position of a vehicle by receiving the radio signal, the storage medium having road data stored therein. The road data reading means for reading the road data around the calculated current position, the speed detecting means attached to the vehicle for detecting the vehicle speed, and the radio signal not being received, are detected. A traveling distance calculating means for calculating the traveling distance of the vehicle from the time when the current position of the vehicle is finally calculated by the first position calculating means, and when the radio signal is not received, Based on the current position calculated last by the position calculating unit No. 1 and the traveling distance from the time when the position was calculated to the present time, the road data near the position is referred to. Thus, the current position calculation device is characterized by having a second position calculation means for calculating the current position of the vehicle. 2. The road data corresponding to the position according to claim 1, based on the road data read by the road data reading means and the current position of the vehicle calculated by the first position calculating means. The second position calculating means further has a road position acquiring means for obtaining a position on the inside road, and the second position calculating means replaces the current position calculated last by the first position calculating means with the calculated current position. A current position calculating device characterized in that the current position finally obtained by the road position acquisition means based on the position is used. 3. The second position calculation means according to claim 2, wherein the second position calculation means is equivalent to the travel distance calculated by the travel distance calculation means from the current position finally obtained by the road position acquisition means. A current position calculating device, characterized in that a position moved along a road in the road data in which the position exists is set as a current position of a new vehicle. 4. The range according to claim 3, on the road in the road data in which the current position finally obtained by the road position acquisition means exists, from the position to a predetermined distance position in the traveling direction of the vehicle. Further has a branch point detecting means for detecting whether there is a branch point, the second position calculating means, when the branch point detecting means detects a branch point, without calculating the current position, A current position calculation device, which outputs a non-display signal indicating that the current position has not been calculated. 5. The display device according to claim 4, further comprising display means for displaying the input current position of the vehicle on a map showing a peripheral region of the position, wherein the road data reading means includes road data and map. And a map medium to be displayed on a display means together with the road data around the current position when the storage medium storing the data is received. When the radio signal is received, the first position calculation is performed. When the current position calculated by the means is input to the display means as the current position of the vehicle and the radio signal is not received, the current position calculated by the second position calculation means is displayed on the display means as the current position of the vehicle. When the non-display signal is output from the second position calculating means, the display means receives the signal and is different from the case where the current position of the vehicle is input. Current position calculating system which is characterized in that the display by a predetermined form.