JPS6366479A - Gps position measuring apparatus - Google Patents

Abstract

PURPOSE:To achieve a satellite selection work quickly, by calculating radio wave shielding requirement from a status data of topographic undulation. CONSTITUTION:A space requirement of shielding radio waves to a running vehicle from a satellite is calculated by a shielding requirement calculating means 2 from state information of topographic undulation on a map stored by a topographic undulation status information memory means 1. The shielding requirement thus calculated by the means 2 is used to select optimum satellite from a space free from the possibility of shielding radio waves by an optimum satellite selection means 3. This enables the selecting of a satellite from a space area with an excellent view thereby enabling a quick satellite selection work. Then, a radio wave from a satellite selected is received by a radio wave receiving means 4 to compute the position of a vehicle by a position computing means 5 based on the received radio wave.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a GP that is useful for use in a vehicle route guidance device.
S (G Iobal Positionin(
J S VStem) relates to a position measuring device.

[Prior Art] A GPS positioning device measures the position of an object by receiving radio waves from an artificial satellite for a plurality of satellites necessary for positioning. 1986-15573, Institute of Electronics and Communication Engineers Technical Research Report Vol. 84. Nn, 78.5ANE84-1
2. Automobile Technology 1985° Vol. 39-1 (Satellite Navigation Global Positioning System), Voyage No. 62 i'JAVsTAR/GPS (Global Positioning System)
I am familiar with etc.

By the way, conventional GPS positioning devices create a predetermined combination of satellites from a large number of satellites orbiting in the sky, and calculate the DOP ([) 1lution, which is an index of deterioration in positioning accuracy.
of Precision) and calculate the DO
Receive satellite radio waves for the satellite combination with the minimum P value,
It is configured to calculate the position of the positioning object.

However, with the conventional GPS position measuring device as described above, it takes a lot of time to select a satellite, and when the object to be positioned is a vehicle, the topography changes as the vehicle travels. Satellite radio waves are often blocked by buildings or mountains, making it impossible to receive signals from the selected satellite, making it difficult to perform stable positioning.

[Purpose of the Invention j The object of the present invention is to improve the above-mentioned problems and provide a GPS positioning device that can quickly select satellites and perform stable positioning regardless of terrain changes. .

[Summary of the Invention] In order to achieve the above object, the present invention, as shown in FIG. , a shielding condition calculating means 2 for calculating a spatial condition under which radio waves from a satellite to a traveling vehicle are shielded due to the terrain undulations; and the means 2
optimal satellite selection means 3 for selecting an optimal satellite from a space where there is no risk of radio wave shielding using the shielding conditions calculated in;
Radio wave receiving means 4 that receives radio waves from the selected satellite, and position calculation means 5 that calculates the vehicle position based on the received radio waves.
This system calculates the shielding conditions that may cause radio waves to be blocked according to the topographical ups and downs of the vehicle's travel location, and quickly and optimally selects only the satellites that are not likely to be radio waves blocked. .

[Embodiment 1] An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a block diagram of a vehicle route guidance device equipped with a GPS position measuring device according to an embodiment of the present invention.

As shown in the figure, the vehicle route guidance device includes a system bus 6
, GPS receiver 7, CPU 8, and system ROM
9, RAM 10, sensor interface 11,
Video RAM 12 and operation panel interface 13
, an input operation section 14 , and an external memory 15 are connected to each other.

The sensor interface 11 includes a distance sensor 16 that outputs a predetermined amount of pulse signals every time the vehicle travels a certain distance.
and a direction sensor 17 that detects the traveling direction of the vehicle. A CRT 18 is connected to the video RAM 12. The operation panel interface 13 has a CRT1
A transparent operation panel (touch panel) 19 provided on the front surface of 8 is connected.

The GPS receiver 7 includes an antenna 7A as a part of the radio wave receiving means 4 shown in FIG.
Based on the occlusion conditions calculated by the a occlusion condition calculation means 2 of 8 (described in detail in Figs. 11 to 19 (a) and (b)), the information necessary for position calculation is determined from within a limited area. A predetermined number of satellites are selected and positioning processing of a predetermined dimension is performed. The number of satellites required for position calculation is three for two-dimensional positioning and four for three-dimensional positioning. Furthermore, the optimal combination of satellites is determined by the combination that minimizes the DOP value.

Based on the program stored in the system ROM Q, the CPU 8 performs calculations of estimated (integral) positions, correction of estimated positions, calculation of shielding conditions for satellite selection, and various other route guidance processes.

The distance sensor 16 outputs a fixed amount of pulse signals every time the vehicle travels a fixed distance. The direction sensor outputs a signal indicating the direction in which the vehicle is traveling. The CPU inputs these signals via the sensor interface 11, detects the vehicle's movement vector or its scalar suspension, calculates the vehicle's current position by summing the movement vector to the reference position, and calculates the vehicle's current position based on this position. Provide route guidance. However, the Ht position determined like a mouth is corrected as appropriate based on the current position detected by the GPS receiver 7.

The CRT 18 is for providing guidance and the like.

The operation panel 19 is used to input the starting point and destination. The input operation unit 14 is formed of a so-called keyboard, from which various commands can be issued.

FIG. 3 shows a block map, and FIG. 4 shows a memory map of the external storage memory 15 created for the map.

As shown in Figure 3, a map 20 represented by XY, I markers
are blocks (1), (1-2) of size α and β in length and width.
> (3-3), and the external memory 15 is configured to store various types of information block by block.

The area start address storage area M1 shown in FIG. 4 is the area M2 . This is an area for storing the start address of M3...

The road data storage order Vi, M2 is an area for storing the starting and ending point coordinates of the linearly approximated road segment 11 shown in FIG. 3 and information necessary for route guidance in relation to the line segment i. It is.

The terrain (sea/river/railway) data storage area r/A3 is an area for storing data regarding the ocean, rivers, and railroads for route guidance.

The data storage area M4 (points, public facilities, etc.) is an area for storing points, such as public facilities, for route guidance.

The character data storage area M5 is for route guidance.
This is an area for storing character display data to T18.

The area name search data storage area M6 is an area for storing local names of cities, towns and villages for area name searches in route guidance.

The building data storage area M7 is an area for storing data for calculating shielding conditions regarding buildings.

Details of the building data storage area M7 will be explained in detail with reference to FIGS. 5 to 7. FIG. 5 is an explanatory diagram showing the three-dimensional layout of the building, FIG. 6 is an explanatory diagram of the memory map, and FIG. 7 is an explanatory diagram of the data format.

As shown in FIG. 5, the building 21 is approximated by a rectangular parallelepiped with a height h passing through the endpoints (X+, Y+), and (X2, Y2) on the map coordinates XY.

As shown in FIG. 6, the building data storage #4 area M7 is divided into a start address storage area M7a and data areas M7b, M7c, etc. for each block. ] - By searching for an address, it is possible to immediately search for the starting address of a desired block.

As shown in FIG. 7, each data #11tM 7 a,
The format of M7b... is the end point coordinates (×1
°Y+>, (X2, Y2) are stored in association with height data h.

In Baidu FIG. 4, the contour data storage area M8 is an area in which terrain having heights such as mountains and hills is expressed by contour line data approximated by straight lines connecting contour points with line segments.

Details of the contour data storage area M8 will be explained in detail with reference to FIGS. 8 to 10. FIG. 8 is an explanatory diagram of contour lines, FIG. 9 is a detailed diagram of a memory map, and FIG. 10 is an explanatory diagram of a data format.

As shown in Fig. 8, points (X+, Y+) (X2, Y
2), (X3.Y3)..., (X5, Ys), (X
s, Ys), (X7, Yy),
By connecting each line segment, a contour line approximated by a straight line is represented. As shown in FIG. 9, the structure of the memory map is similar to that shown in FIG.

As shown in FIG. 10, the data format is stored in such a manner that height data is associated with the coordinates of the starting point and ending point of each line segment.

Next, the shielding condition calculation speed performed by CPIJ8 is explained in the 11th section.
This will be explained using FIGS. 19(a) and 19(b).

FIG. 11 is an explanatory diagram of paired blocks in shielding condition calculation, and FIGS. 12 and 13 are explanatory diagrams of the combined state of building data and contour line data in the stack area of the RAM 10.

In addition, Fig. 14 shows the angle of elevation of the apex of the shielding object (hereinafter also referred to as the maximum shielding elevation angle) (θ~IA, X1~θMA
An explanatory diagram showing the azimuth lines 11 to 8 divided into 8 equal parts for determining FIG. 18 is an explanatory diagram showing an example of shielding condition data.

Further, FIGS. 19(1) and 19(b) are flowcharts showing the shielding condition exclusion method.

In FIG. 19(a), first, in step 1901, the current position (X, Y) is read, and in step 1902, the block where the position exists is determined, and as shown in FIG. 11, the current position (X, Y) is read. Set the surrounding blocks of the block where exists as the search area, and store the building data and contour line data in this area in RAM as shown in
Read within 10.

The data read into the RAM 10 is arranged in order for each block, and the total number of lines is MAX 1 for building data and MAX 2 for contour line data. It is assumed that each variable is expressed in 16 bits (2 bytes).

In step 1904, variables θMAX1 to θMAX8 for storing the maximum shielding elevation angle shown in FIG. 14 are cleared to zero.

In step 1905, the direction lines 11 to 11 shown in FIG.
! In order to change J, 8 in the order of 11.12.13, set the variable θ to zero.

In step 1906, as shown in FIG. 15, a straight line P passing through the current position (X, Y) and having an inclination θ is determined.

In step 1907, the start address of the building data shown in FIG. 12 is set in the index register 81, and the data line scan counter CX is set to 1.
Initialize.

In steps 1908 to 1916, it is detected whether the straight line P intersects with a building.

First, in step 1908, the ground end point Fimt of the building
Read into rregis'lX+, YI, X2, Y2,
Then steps 1909.1910.1911-19
In step 14, the intersections between the straight line P and each side of the rectangle on the ground of the building are detected, and in step 1912, the intersection coordinates are stored in the stack area.

In steps 1915 and 1916, these operations are performed in RAM.
This is performed for all lines for the building data in 10.

Note that since one line has five variables, the number of bytes is ten. Therefore, every time one line is checked, the index register 81 should be incremented by 10, and the line number scan counter should be incremented by one.

In FIG. 19(b), steps 1917 to 1922
Now, find the intersection between the straight line P and the isoline. The basic idea is the same as for building data.

However, although the building data was checked four times per line data, in the case of equal straight lines, it is one line data, so it is only necessary to check - straight lines.

Through the above processing, the intersection data of the straight line P, the building, and the isoline is stored in the stack area together with the data of its height. In step 1923, the data is extracted as shown in FIG. In this example, the arrangement is as shown in Figure 15,
The straight line P intersects the building on the upper right and the isoline on the lower left, resulting in four intersections.

Thereafter, in steps 1924 to 1933, the maximum shielding elevation angle is determined from the data shown in FIG.

In step 1924, the start address of the intersection data shown in FIG. 17 is set in the index register Sr, and a counter is initialized to 1.

In step 1925, the intersection coordinates X, Y and height data are converted into variables Xl, Y1. Load into H. Step 1926
Now, as shown in Fig. 16, the elevation angle θ for each intersection point is
Find h.

In step 1927, the intersection point has an azimuth offset O~1
It is determined whether the angle is 35° (θMAX1 to θfvlAX4) i5 or 180° to 315° (θMAX5 to θMAX8). The meaning of this equation is that the intersection point has a slope of -22
, 5° (between line molecule L+ and 18 shown in Figure 14)
We are looking at whether it is above or below the straight line.

Steps 1928 and 1929 or Step 193
0 and 1931, among the elevation angles found at the intersection,
Registering the maximum value, θ~jAX[θ/45+1] will be changed to the variable θMA with the azimuth offset set to θ=45° next time.
This means that X is, for example, θ/45+1=2, that is, θMAX2. If you do this for all the intersections, you will get the 15th.
In the example of Figure 16, in the direction of azimuth offset θ, θh2 at intersection 2 is the maximum elevation angle, and offset θ + 180°
In the direction of , θh3 at intersection 3 becomes the maximum elevation angle.

By performing the above processing for azimuth offsets of 0° to 135°, the maximum shielding elevation angles θMAXI to θMA X 8 are determined for all directions shown in FIG.

Next, we will apply the method of using the shielding conditions obtained as above to the second method.
This will be explained using Figure 0.

First, as a prerequisite, it is assumed that the vehicle route guidance device shown in FIG. 2 mainly performs dead reckoning navigation, and performs various route guidance processes such as guidance display based on estimated positions. On the other hand, the GPS position measuring device measures the position at predetermined intervals (for example, 5 seconds), and if positioning is possible under certain conditions, the position measurement is performed to confirm the estimated position. . The above-mentioned shielding conditions are used by the optimum satellite selection means 3 in the GPS position measuring device H.

First, in step 2001, it is determined whether there are three or more visible satellites. If the number is 2 or less, GPS positioning is impossible, so the process moves to step 2002, where the positioning possible flag is reset, and the process returns with an interrupt.

If it is determined in step 2001 that there are three or more visible satellites, two-dimensional positioning is possible, so the process moves to step 2003.

In step 2003, it is determined whether or not the current mode is the departure point mode. If the current mode is the departure point mode, the process moves to step 2004, and if the current mode is not the other mode, the process moves to step 2005. The departure point mode is a mode provided for setting conditions for departure, such as a departure point and a destination, for the convenience of route guidance.

In step 2004, the three satellites with the best DOP are selected from all directions regardless of the shielding conditions.

On the other hand, in step 2005, considering that the current mode is a mode other than the departure point mode, it is determined whether the three satellites already selected are receivable. If all three satellites are receivable, it is possible to continue positioning, so no new satellite selection is required, and the process proceeds to step 2010; however, if not, the process proceeds to step 2006. Proceed, here the 19th
The shielding conditions shown in Figures (a) and (b) are calculated.

Step 2007 shows road flag state determination processing. If it is determined that the road flag is "0", the process moves to 2004 considering that the vehicle is not on the road, and it is determined that the road flag is "1". If so, the process moves to step 2008''\ to perform predetermined processing considering that the vehicle is on the road.

In step 2008, there are three receivable satellites in an area (observation area) other than the area defined by the shielding conditions shown in FIG.
Determine whether there are more than
Move to 09 and here it is.

Select the three best satellites of P. The shield rA region is the first
Line segment 11 shown in Figure 4! Maximum 18 specified on LS
Regarding the elevation angles θMAX1 to θMAX8, it is specified that radio waves are shielded in the elevation angle portion smaller than this elevation angle within a range of ±22.5°.

If it is determined in step 2008 that three satellites are not found within the viewing area, the process is performed in step 2004.
Then, the three satellites with the best DOP are selected from all directions.

In step 2010, the positioning enable flag is set, and in step 2011, the current position (Xc, Yo
) is calculated, and then, in step 2012, the current position register is rewritten, and in step 2013, the contents of the current position register are transferred to the screen buffer.

As described above, in this example, the shielding area is set according to the shielding conditions shown in FIG. 18, and three satellites are selected in areas other than the shielding area according to the flowchart shown in FIG. 20.

Therefore, the GPS position measuring device according to this example can automatically calculate a viewing area where there is no risk of being blocked by radio waves using building data and contour line data, and can quickly select the optimal satellite from the area with a good view. This enables stable positioning.

In the above embodiment, the number of azimuth lines shown in FIG. 14 was 8, but it goes without saying that this number may be any other number, such as 16.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be implemented in other embodiments by making appropriate design changes.

[Effects of the Invention] As described above, the GPS position planning device according to the present invention can calculate radio wave shielding conditions using topographical relief state data and select a satellite from a spatial region with a good view. Therefore, you can quickly select one satellite.
Moreover, stable positioning can be performed.

[Brief explanation of drawings]

FIG. 1 is a diagram corresponding to claims of the present invention, FIG. 2 is a block diagram of a vehicle route guidance device equipped with a GPS position measuring device according to an embodiment of the present invention, and FIG. 3 is a diagram of a block map. An explanatory diagram, FIG. 4 is a memory map of the external storage memory 15 created for the map, FIG. 5 is an explanatory diagram showing the three-dimensional layout of buildings, FIG. 6 is an explanatory diagram of a memory map of building data, and FIG. is an explanatory diagram of the data format of building data, Fig. 8 is an explanatory diagram of isolines, Fig. 9 is a detailed diagram of the memory map of contour line data, Fig. 10 is an explanatory diagram of the data format of contour line data, and Fig. 11 is an illustration of occlusion. Fig. 12 is an explanatory diagram of the building data and contour line data in the stack area of RAM, and Fig. 14 is an explanatory diagram of the paired blocks in condition calculation.
8) An explanatory diagram showing the azimuth line intersections 1 to 8 divided into 8 equal parts, Figures 15 and 16 are explanatory diagrams showing the calculation method of the maximum shielding elevation angle, and Figure 17 is the intersection of the work area An explanatory diagram of the data, Fig. 18 is an explanatory diagram showing an example of calculated occlusion condition data, Figs. 19 (a) and (b) are flowcharts showing the occlusion condition calculation method, and Fig. 20 is a current location correction process using GPS. FIG. 1... Terrain relief state information storage means 2... Shielding condition calculation means 3... Optimal satellite selection means 4... Radio wave reception means 5... Position calculation means Agent Patent attorney Yasuo Miyoshi 1st Fig. 5 Fig. 6gj Fig. 7 Fig. Bt Fig. 9vA Fig. 10 Fig. 11 Fig. 12, ・Number of lights - 22222 Fig. 13 Fig. 14 2nd line P Fig. 16 Fig. 17iff Fig. 18 Hand-chan city Principal offender 4 (method) December 10, 1986

Claims (4)

[Claims] (1) Terrain relief state information storage means for storing state information of terrain relief on a map; shielding condition calculation means for calculating spatial conditions under which radio waves from a satellite to a traveling vehicle are blocked by the terrain relief; an optimal satellite selecting means for selecting an optimal satellite from a space where there is no risk of radio wave shielding using the shielding conditions calculated by the means; a radio wave receiving means for receiving radio waves from the selected satellite; A GPS position measuring device comprising: a position calculation means for calculating a vehicle position. (2) The GPS position measuring device according to claim 1, wherein the terrain relief state information storage means stores contour line data approximated by a straight line connecting contour points with line segments. (3) The GPS position measuring device according to claim 1, wherein the terrain relief state information storage means stores building data in which a building is approximated by a rectangular parallelepiped. (4) The shielding condition calculation means calculates the maximum value of the apex elevation angle of the terrain relief for each direction equally divided with the current position of the vehicle as the center based on the stored content of the terrain relief state information storage means. The GPS position measuring device according to scope 1.