JPH0372285A - Current location display device for mobile objects - Google Patents

Abstract

PURPOSE:To enable selection of an optimum satellite whereby an error is reduced to the minimum, by comparing the present places of a moving body which are calculated from a distance of the moving body from a GPS satellite and position data from a road-side antenna. CONSTITUTION:This apparatus redraws a displayed map on a display screen sequentially with a change of the present place and synthesizes and displays the present place on the displayed map. On the occasion, a satellite navigation means 31 receives a radio wave emitted from a GPS satellite, calculates a distance between the GPS satellite and the present place and calculates the present place of a moving body. Meanwhile, a road-side position information receiving means 33 receives position data transmitted from a road-side antenna disposed at a predetermined prescribed position in a road traffic system and calculates the present place of the moving body. An optimum satellite selecting means 35 compares positional informations from the means 31 and 33 with each other and selects an optimum satellite in the means 31.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a current location display device for a mobile object suitable for a navigation system or the like.

(Prior Art) Currently, in GPS navigation, the geometric configuration (DOP) of satellites is used as a satellite selection criterion for position calculation (for example, Japanese Patent Laid-Open No. 198074/1983).

(Problem to be Solved by the Invention) The above-mentioned DOP value is an index determined only by the satellite placement situation, and includes errors in satellite position data, errors related to ionosphere radio wave propagation delay, errors related to tropospheric radio wave propagation delay, etc. Therefore, there is a problem that the combination of satellites with the minimum DOP value is not necessarily the optimal combination of satellites.

Further, even if an optimal satellite is selected, there is a problem in that an error occurs in the calculated position of the moving body because correction of errors due to ionospheric propagation delay, etc. is not performed.

The present invention has been made in view of the above, and an object thereof is to provide a current location display device for a mobile object that enables selection of an optimal satellite with the least error in satellite navigation means. .

[Transmission of invention]

(Means for Solving the Problems) In order to achieve the above object, the current location display device for a mobile object of the present invention synthesizes and displays the current location on the display map while sequentially rewriting the display map on the display screen as the current location moves. As shown in FIG. 1, this current location display device for a mobile object receives radio waves emitted from a GPS satellite and calculates the distance between the GPS satellite and the current location of the mobile object.
Satellite navigation means 31 that calculates the current location of a mobile object, and roadside position information reception that calculates the current location of the mobile object by receiving device data transmitted from a roadside antenna placed at a predetermined position on the road transportation network. means 33, and optimum satellite selection means 35 for comparing the device information transmitted from the roadside position information receiving means and the position information calculated by the satellite navigation means to select the optimum satellite for the satellite navigation means. (Function) The current location display device for a moving object of the present invention receives radio waves from a GPS satellite, calculates the distance between the GPS satellite and the current position of the moving object, and displays the current location of the moving object. The current value of the mobile object is calculated from the device data transmitted from the roadside antenna, and the two current values are compared to select the most suitable satellite for the satellite navigation means.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 2 is a block diagram showing electrical hardware transmission of a current location display device for a mobile object according to an embodiment of the present invention. The current location display device for a mobile object shown in the figure has its entire operation controlled by a CPUI consisting of a microprocessor, etc., and a system bus 2 connected to the CPUI has an I1
0 controllers 3 and 4, SC3I controller 5,
Graphic controller 6, V-RAM7, ROM8
, D-RAM9, Kanji ROM10. Backup RAM
II, and an expansion I10 controller 21 are connected.

In addition, the I10 controller 3 has an orientation sensor 12
P14 and the A/D converter 15, and the distance sensor 13 is also directly connected. The I10 controller 4 is connected to keys 16 for inputting various information manually, and is also connected to a speaker 17 via a sound generator 18.

Furthermore, the 5C8I controller 5 and the graphic controller 6 each have a CD-ROM19 and a CRT.
20 are connected.

The CRT 20 has VDT (Visual Dls
The image information to be displayed on the CRT 20 is written to the VRAM 7, and the image information to be displayed on the CRT 20 is also written to the VRAM 7. Map information is stored on CD-ROMI 9.

Note that the current value of the vehicle is detected using the signal outputs of the direction sensor 12 and distance sensor 13 as well as the signal outputs of the GPSRx 22 and the beacon Rx via the expansion I10 controller 21.

Further, the overall control of this device is performed by the CPU executing a system program stored in the ROM 8.

Next, the operation will be explained by referring to the flowcharts shown in FIGS. 3(a) and 3(b). The processing shown in the figure shows the contents of the control program stored in the ROM 8.

First, in FIG. 3(a), when the program starts, initial setting processing is performed by input operation using the key 16 (step 100), and through this processing, the initial position of the vehicle is manually set, and the vehicle is The current location is displayed (step 110). Here, the manual effort for determining the initial position can be omitted by inputting the GPS JflJ position.

As described above, when the initial setting process and the current value display process are completed, the device enters the operating state, and as the vehicle moves, the sluggish running position detected via the direction sensor 12 and the distance sensor 3 is calculated. (Step 120).

Next, the radio waves emitted from the GPS satellite are received, and the G
The distance between the PS satellite and the current location of the mobile object is calculated to obtain the measured position of the mobile object (step 130). Here, the method for selecting satellites to be used for positioning is based on the method for selecting satellites with the lowest rank, which will be described later. However, if reception by the selected satellite is impossible for some reason, the next order selection method will be used.

Furthermore, since the position determined in step 130 includes errors due to ionospheric propagation delays,
) to correct the error by subtracting the difference vector calculated in the interrupt processing (step 140). Since the respective positions obtained in steps 120 and 140 are the same information obtained by different means, a more accurate most likely estimated position is obtained by filtering them (step 150). Once the current location of the moving body has been determined in this manner, the displayed map is rewritten in accordance with the movement (step 160).

By repeating the processes from steps 110 to 160 described above, the map on the screen is rewritten as the mobile object travels, and the current location is displayed on the map.

When the position data spot-transmitted from the roadside antenna is received while driving while displaying the above-mentioned map, the interrupt processing (INTR) shown in FIG. 3(b) is performed.
) is activated.

In the interrupt process shown in FIG. 3(b), first, the received data is converted into coordinates on a map (step 200). The coordinates obtained here are extremely accurate because they use spot reception. Therefore, these coordinates are taken as the current location (step 210).

Next, the satellite navigation means selects three or four satellites from among the receivable satellites, calculates the distance between the selected satellites and the mobile object, and obtains the current location of the mobile object (step 22).
0). Since the current location obtained here has errors due to ionospheric propagation delays, etc., it does not match the value obtained in step 210.

Therefore, calculate the difference vector between the value found in step 210 and the value found in step 220, and store this difference vector in the D-RAM 9 as correction data for the satellite combination in step 220 (step 230).
.

The operations of steps 220 and 230 are repeated by changing the combinations of satellites (step 240), and once the difference vectors for all combinations have been calculated, the difference vectors are ranked in descending order (step 2).
50), the interrupt processing ends.

In the above embodiment, in step 230, each time a new difference vector is calculated, the correction data is rewritten with the difference vector, but a weighted average is calculated in consideration of continuity with past data. The weighted average value may be used as the correction data.

In addition, in step 240, when selecting 3 or 4 satellites from the range of receivable satellites, all combinations are extracted. It is also possible to control the CPU so as not to place too much burden on it by setting restrictions such as stopping the calculation after a predetermined time.

〔Effect of the invention〕

As explained above, according to the present invention, radio waves from a GPS satellite are received, the distance between the GPS satellite and the current value of the mobile object is calculated, the current value of the mobile object is calculated, and the current value of the mobile object is calculated. The current location of the moving object is calculated from the device data transmitted from the antenna, and the two current values are compared to select the most suitable satellite for satellite navigation, so the current location of the moving object can be calculated accurately. can. Additionally, errors included in the position calculated using the selected satellite are canceled out, making it possible to calculate a more accurate current position of the moving object.

[Brief explanation of drawings]

FIG. 1 is a diagram corresponding to claims of the present invention, FIG. 2 is a block diagram showing electrical hardware transmission of a current location display device for a mobile body according to an embodiment of the present invention, and FIG. It is a flow chart showing the operation of the current location display device. 1. ・CPU. 5. ・SC3I controller, 6. ・Graphic controller, 7. ・V-RAM. 8...ROM. 12. ・Direction sensor, 13. ・Distance sensor, 22. ・GPSRx. 23. ◆Beacon Rx0 (a) (b)? ! , Figure 3

Claims (2)

[Claims] (1) A current location display device for a mobile object that sequentially rewrites the displayed map on the display screen as the current location moves and displays the current location compositely on the displayed map, and which receives radio waves emitted from GPS satellites. A satellite navigation means that calculates the distance between a GPS satellite and the current location of a mobile object, and a position transmitted from a roadside antenna installed at a predetermined location on the road transportation network. roadside position information receiving means that receives data and calculates the current location of a mobile object; and a roadside position information receiving means that receives data and calculates the current location of the mobile object, and compares the position information output from the roadside position information receiving means with the position information calculated by the satellite navigation means, and performs the satellite navigation. 1. A current location display device for a mobile object, comprising: optimum satellite selection means for selecting an optimum satellite in the means. (2) The current position calculated in the satellite navigation means based on the difference vector between the position information outputted from the roadside position information means and the position information calculated from the satellite navigation means, and the combination of the satellites from which the difference vector was obtained. 2. The current location display device for a moving body according to claim 1, wherein the current location display device for a moving object corrects the value.