JPH0613977B2 - Vehicle guidance device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle running guidance device, and more particularly to a vehicle in which a marking for displaying the current position is changed corresponding to the detection accuracy of the current position of the vehicle. Travel guidance device.

<< Prior Art >> A vehicle traveling guidance device is a device for guiding a vehicle to a destination without error by displaying a traveling map and a current position of the vehicle on a display means such as a CRT together with a road map of a region where the vehicle is traveling. An example thereof is disclosed in Japanese Patent Laid-Open No. 58-70125.

This type of device has a current position detecting means for detecting the current position of the vehicle.
As disclosed in Japanese Patent Publication, there is provided a means for detecting the traveling distance and azimuth of a vehicle from a certain reference point and grasping the current position of the vehicle as a relative position from the reference point. There is.

However, this current position detecting means has a drawback that the measurement errors of the traveling distance and the azimuth are accumulated and the accuracy is lowered.

Therefore, there has been proposed a means for receiving a radio wave emitted from a satellite and obtaining the current position of the vehicle as an absolute position (latitude / longitude) on the earth.

<< Problems to be Solved by the Invention >> The current position detecting means using the above-mentioned satellite is a Global Positioning System which is currently under development.
m, hereinafter abbreviated as GPS), and it is said that this system can receive the radio waves emitted from a plurality of artificial satellites and measure the current position of the vehicle with a maximum accuracy of about 20 m. There is.

However, the measurement accuracy of the current position detecting means varies depending on the position of the satellite, the perturbation of the satellite, the state of the ionosphere, and the like.

Therefore, even if the current location is marked and displayed on the map, the user cannot know how accurately the location is displayed, and information for guiding the vehicle cannot be sufficiently transmitted.

The present invention has been made in view of such problems, and an object thereof is to allow a user to visually recognize the measurement degree of the current position of a vehicle by a marking display and to provide sufficient information for vehicle guidance. Another object of the present invention is to provide a vehicle travel guidance device that can be appropriately transmitted.

<< Means for Solving Problems >> In order to achieve the above-mentioned object, the present invention provides, in a vehicle travel guidance device, a display means (a) for displaying information for driving guidance of a vehicle, and this display means ( There are few storage means (b) for storing information necessary for driving guidance including at least a map displayed in a) and positioning means (c) for receiving the radio wave from the satellite to detect the current position of the vehicle. And the present location detecting means (d), the deterioration coefficient detecting means (e) for detecting the distance measurement error of the positioning means (c), and the display means (a).
A current location display means (f) for marking and displaying the current position detected by the current location detection means (d), and a display control means for varying the marking display in correspondence with the deterioration coefficient of the deterioration coefficient detection means (e). (G) and.

Here, the deterioration coefficient (Geometrical Dilution Of Prec
ision, which is abbreviated as GDOP) is a coefficient that represents an increase in measurement error that is determined by a geometrical function between the satellite in use and the vehicle when measuring the current position.

In addition, as a mode of changing the marking display, for example, the size of the display itself is changed corresponding to GDOP, or the color of the marking is changed by using a color CRT as the display means, and further, these variable means are changed. Various means such as combination and changing the shape of the marking are conceivable, but those visible at a glance while the vehicle is traveling are preferable.

<< Operation >> According to the vehicle running guidance device having the above configuration, the marking display indicating the current position of the vehicle also indicates the detection accuracy of the current position detection means, and the user can visually recognize this, for example, When the vehicle is being guided by this device and the intersection that turns in any direction is approaching, if the size of the marking display includes the intersection, the accuracy range corresponding to the size of the marking display is obtained. It can be confirmed that there is a corresponding intersection.

<Example> Hereinafter, a preferred example of the present invention will be described in detail with reference to the accompanying drawings.

2 to 5 show an embodiment of the vehicle running guidance device according to the present invention.

The traveling guidance device shown in FIG. 2 is roughly composed of a display means 10, a storage means 12, a current position detection means 14 and a control means 16, as shown in the overall configuration of FIG.

The display means 10 displays information for guiding the traveling of the vehicle, for example, a map of the area where the vehicle is currently traveling, a guidance target location set on the map, the current location obtained by the current location detecting means 14, and the like. Generally, a monochrome or color CRT, a liquid crystal display element, a plasma display, an electroluminescence, etc. are used, and the displayed information is controlled by the control means 16.

The storage means 12 stores at least information necessary for driving guidance including a map. For example, a CD-ROM or a magnetic tape is used. Especially, the CD-ROM has a large storage capacity, is compact, and has an access time. Since it is short, it is suitable as a storage means for mounting on a vehicle, and the stored information may store a vehicle start-up inspection procedure, a tire replacement procedure, etc. in addition to the map.

The information is taken out from the storage means 12 by mounting a storage medium such as a compact disc or a tape on the reproducing device and controlling the reproducing device by the control means 16.

The current position detecting means 14 receives a radio signal from a satellite to detect the current position of the vehicle, which is a positioning system (GPS).
The receiver 14a may be provided at least, and a sensor for detecting the current position by known geomagnetism may be additionally provided.

The principle of detecting the current position of the vehicle by GPS will be briefly described below.

As schematically shown in FIG. 3, the GPS is composed of a plurality of antennas A _{1 to} A ₄ distributed over the earth E at appropriate intervals, a plurality of satellites S _{1 to} S _4, and a user P. Each satellite S _{1 to} S ₄ is configured and controlled by the control station C via the antennas A _{1 to} A ₄ . In addition, an antenna A is attached to each satellite S _{1 to} S _4.
A receiver for receiving signals from _{1 to} A _4, a transmitter for emitting various information signals to the user P, and a receiver for receiving signals from the satellites S _{1 to} S ₄ respectively by the user P. I have it.

Here, if there is a clock that is completely synchronized with the transmission point and reception point of the radio wave and the transmission signal is controlled by that clock, if the reception timing is measured at the reception point, the propagation of the radio wave between the transmission and reception points The time can be obtained, and the distance between the transmitting and receiving points can be obtained by multiplying it by the speed of light.
Now, in the visual field (receivable area) of the user P, three satellites S ₁ . S ₂ , S ₃ , each of the satellites S ₁ . S ₂ and S ₃ are transmitting the distance measurement signal by the clock synchronized with each other,
Moreover, it is assumed that the positions of the satellites S _{1 to} S _{3 at} the time of reception have been accurately obtained. If the reception time of these signals is measured at the reception point P, each satellite S ₁ . The distance between S ₂ , S ₃ and the receiving point P is obtained, and the position of the user P is determined by the satellite S ₁ . It can be obtained as the intersection of three spherical surfaces centered on S ₂ and S ₃ .

However, in reality, it is difficult to completely synchronize the clocks of the transmitting point and the receiving point, and an error occurs due to the delay of the received signal. In this system, as described above, the satellite S ₁
Since the measurement accuracy includes the ranging error due to the position error of ~ S ₄ and the state of the ionosphere, etc., the signals emitted from the satellites S _{1 to} S ₄ to the user P indicate the magnitude of the ranging error. Data of the deterioration coefficient (GDOP) which is a coefficient is included.

Table 1 below is an example of the types and magnitudes of distance measurement errors that have been published, and the positions when users actually use this system simply by multiplying these values by GDOP. The detection accuracy can be calculated.

On the other hand, the control means 16 is composed of a so-called microcomputer in this embodiment, and has an input / output interface 16a connected to the display means 10, the storage means 12 and the present location detection means 14, respectively, and a read only memory (ROM). ) In accordance with the procedure described in 16b, the signal from the current position detecting means 14 is received and operated through the input / output interface 16a, and the storage means 12 is controlled based on the result, and the stored information, for example, the current position is displayed on a map. A CPU 16c that performs processing such as displaying,
It is composed of a random access memory (RAM) 16d for temporarily storing the taken-in data.

In particular, in this embodiment, the control means 16 is configured to change the size of the marking display of the current position displayed on the display means 10 in correspondence with the GDOP value from the GPS described above.

The size D of the marking display is determined as follows. In this embodiment, a case where a dot display CRT is used as the display means 10 will be described.

First, the size P _{0 of the} mark with respect to the scale of the map on which the marking is displayed is calculated by the following equation.

P ₀ mm = GDOP × 20 × 10 ³ / S (1) S in the formula is the scale of the map, and 20 × 10 ³ is GPS.
It is the highest accuracy value (20m) that can be detected by the system.

Then, the minimum dot of the display means 10 to P ₀ determined by formula size d ₀ Display the integer value although divided by (varies depending CRT type but about generally 0.4 mm) means 1
0 is the size D of the marking display shown above.

For example, if the map scale is 1 / 25,000 and the GDOP value is 5 as shown in FIG. 4, P ₀ = 5 × 20 × 10 ³ /
2.5 × 10 ⁴ = 4 mm, and D = INT (4 / 0.4) = 10 (dots) (2).

In other words, if the size of the display marking is determined as described above, if the detection accuracy of the current position by the DPS is good, the GDOP value becomes small and the size D of the marking display becomes small, but the detection accuracy becomes poor. When it comes to GDOP
The larger the value, the larger the marking display size D.

As a result, the user can easily and reliably visually recognize the detection accuracy of the current position detection means 14.

FIG. 5 shows a flowchart of the processing procedure of the control means 16 that makes the marking display variable as described above.

When the routine for determining the size of the current position display marking is started (step), first, in step, the GPS receiver 14a of the current position detecting means 14 is operated, and the current position of the vehicle is detected by receiving the radio signal from the satellite. At the same time, the GDOP value is detected by the signal from the satellite in the same manner as the step.

Then, in step, P ₀ is calculated by the above calculation formula (1), in step, the number of dots D of the display marking is calculated based on the value of P ₀ , and based on this calculated value, the current position detected in step is The number D is displayed and the process returns to the main routine in steps.

In addition, when the display color of the marking display is variable with respect to the GDOP value, for example, the color corresponding to the GDOP value is predetermined and the RAM 16d of the control means 16 uses this.
The color corresponding to the color may be read out and displayed on the display means 10 in color when the GDOP value is detected in the flow of FIG.

Further, even when the marking display is variable in shape, it is possible to deal with it by preparing a similar program.

<< Effects of the Invention >> As described in detail in the above, in the vehicle travel guidance device according to the present invention, the vehicle is displayed by variably displaying the current position of the vehicle in correspondence with the detected accuracy. It is possible to recognize the range within which the GPS position is located and to visually recognize the GPS reception state.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of the device of the present invention, FIG. 2 is a block diagram showing the overall configuration of an embodiment of the device of the present invention, and FIG. 3 is a schematic explanatory diagram of a GPS system. 4 is an explanatory view showing an example of the marking display of the device of the present invention, and FIG. 5 is a flow chart showing an example of the processing procedure of the control means. 10 ... Display means, 12 ... Storage means 14 ... Present location detection means 16 ... Control means

Claims (1)

[Claims] 1. A display means for displaying information for guiding a vehicle to travel, a storage means for storing information necessary for driving guidance including at least a map displayed on the display means, and a radio wave from a satellite. Current position detection means for receiving at least the current position of the vehicle to detect the current position of the vehicle, deterioration coefficient detection means for detecting a distance measurement error of the positioning means, and the current position detected by the current position detection means on the display means. A vehicle running guidance device comprising: a current location display means for marking and displaying a position; and a display control means for varying the marking display in correspondence with the deterioration coefficient of the deterioration coefficient detecting means.