JP2003177173A - Position measuring device for moving body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a highly-accurate position measuring function by utilizing two satellites in a position measuring device for moving body. <P>SOLUTION: This position measuring device is equipped with an antenna 1 for receiving a radio wave transmitted from each satellite, an antenna attitude adjusting device 2 for adjusting antenna attitude to each satellite, a demodulator circuit 4 for detecting altitude/latitude/longitude information included in the radio wave from each satellite, an elevation angle detection circuit 5 and an azimuth detection circuit 6 for detecting the elevation angle and the azimuth of the antenna to each satellite, and a position measuring operation circuit 7 for deriving the latitude/longitude information of two candidate positions to the own position based on the altitude/latitude/longitude information on both satellites and the elevation angle of the antenna, selecting one candidate position coincident with the azimuth of the antenna from between the two candidate positions, and outputting the latitude/longitude information of the candidate position. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning device mounted on a moving body such as an automobile to measure the position of the moving body.

[0002]

2. Description of the Related Art Conventionally, in a GPS (Global Positioning System) which has been put into practical use in a car navigation system, 24 satellites orbit at an altitude of 21000 km, and at least 3 or more satellites are used for positioning. It receives radio waves and uses the principle of triangulation to measure its own position.

By the way, in recent years, a mobile satellite digital radio broadcasting system in which a digital radio broadcasting wave transmitted from a satellite can be received by a receiver mounted on an automobile to enjoy music and the like has reached the stage of practical application. There is.
In the mobile satellite digital radio broadcasting system, the antenna for receiving the digital radio broadcasting wave is movable, and the attitude is adjusted in the direction in which the strength of the received radio wave is maximized, so that the digital radio broadcasting wave can be received with high sensitivity. Can receive. In addition, in mobile satellite digital radio broadcasting, information indicating the position of the satellite is included in the digital radio broadcasting wave, that is, information on altitude, longitude and latitude.
(Hereinafter referred to as altitude / latitude / longitude information) is planned to be included.

Therefore, it is considered to realize a positioning function similar to that of the current GPS by using a receiver for mobile satellite digital radio broadcasting, and use the receiver as a car navigation device.

[0005]

However, in order to realize a positioning function similar to that of the current GPS, it is necessary to use three satellites, which complicates the structure of the receiver and is originally inexpensive. However, there is a problem that the receiver that can be provided to is expensive. Then, the objective of this invention is providing the positioning device of a mobile body which can implement | achieve the positioning function using two satellites, without lowering measurement accuracy.

[0006]

A positioning device for a mobile body according to the present invention measures the position of the mobile body by receiving radio waves transmitted from two satellites orbiting a predetermined orbit. There are antennas that receive the radio waves sent from each satellite, antenna attitude adjustment means that adjusts the attitude of the antenna in the direction in which the intensity of the received radio waves is maximized for each satellite, and the antennas that are received by the antennas. Information detecting means for detecting altitude / latitude / longitude information included in radio waves from each satellite, and antenna angle detecting means for detecting the elevation angle and azimuth angle of the antenna with respect to each satellite adjusted by the antenna attitude adjusting means. And a first arithmetic processing means for deriving latitude / longitude information of two candidate positions with respect to the own position based on the altitude / latitude / longitude information of both satellites and the elevation angle of the antenna. A second arithmetic processing means for selecting one candidate position matching the azimuth angle of the antenna detected for at least one of the complementary positions and outputting latitude / longitude information of the candidate position as a positioning result. I am.

In the positioning device of the present invention, the elevation angle and azimuth angle of the antenna with respect to each satellite are constantly adjusted so that the radio field intensity is maximized. At the time of positioning, the elevation angle and azimuth angle of the adjusted antenna are adjusted. To be detected. In addition, the altitude / contained in the radio waves from each satellite received by the antenna
Latitude / longitude information is detected. Then, based on the altitude / latitude / longitude information for both satellites and the elevation angle of the antenna,
Latitude / longitude information of two candidate positions with respect to the own position is derived. For example, from the altitude / latitude / longitude information of one satellite and the elevation angle of the antenna, define the locus of one circle in which a moving body can exist, and from the altitude / latitude / longitude information of the other satellite and the elevation angle of the antenna. , It is possible to define a locus of one circle in which a moving body can exist. Therefore, the positions of two intersections where these two circles intersect can be narrowed down as two candidate positions where the moving body can be located. The latitude / longitude information of one of the two candidate positions represents the true own position.

Of the two candidate positions, the azimuth angle when one of the satellites is observed from the first candidate position, and the second
The azimuths when observing the satellite from the candidate position No. do not coincide with each other, and one of the azimuths should coincide with the detected azimuth. Therefore, if one candidate position that matches the azimuth angle of the antenna detected for at least one of the two candidate positions is selected, the latitude / longitude information of the candidate position indicates the own position. It will be.

By the way, since the azimuth angle of the antenna is detected with reference to the direction of the earth's magnetism, its detection accuracy is higher than that of the altitude / latitude / longitude information about each satellite and the elevation angle of the antenna. It has to be low. Therefore, in the positioning calculation using these data equally, highly accurate positioning is difficult due to the error included in the azimuth angle of the antenna. On the other hand, in the positioning device according to the present invention, as described above, first, after obtaining the two candidate positions where the mobile body can be located from the altitude / latitude / longitude information of the two satellites and the elevation angle of the antenna, Since the procedure to select the candidate position that is the actual position of the mobile object based on the azimuth angle of the antenna detected for at least one of the satellites is adopted, the altitude / latitude / longitude information and the elevation angle of the antenna are positioning accuracy. However, the azimuth angle of the antenna is only used to select one candidate position from two candidate positions, and does not directly affect the positioning accuracy. As a result, highly accurate positioning is realized.

[0010]

According to the positioning device for a mobile body according to the present invention, a highly accurate positioning function using two satellites can be realized.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a mobile satellite digital radio broadcast receiver will be specifically described below with reference to the drawings. As shown in FIG. 1, a digital radio broadcast receiver according to the present invention has an antenna (1) for receiving satellite digital radio broadcast waves and the antenna (1) as a configuration for realizing a function as a radio receiver. 1)
Antenna attitude adjusting device (2) for optimally adjusting the attitude of the satellite, and a tuner for selecting and receiving a specific channel of the satellite digital radio broadcast wave received by the antenna (1)
(3), a demodulation circuit (4) for demodulating the satellite digital radio broadcast signal obtained from the tuner (3), and an audio output device (9) for outputting an audio signal and a video signal respectively obtained from the demodulation circuit (4). ) And a video output device (10).
The antenna attitude adjusting device (2) automatically adjusts the attitude of the antenna (1) in the direction in which the reception intensity of radio waves is maximized.

Further, the digital radio broadcast receiver according to the present invention detects the elevation angle and azimuth angle of the antenna (1) with respect to two satellites obtained from the antenna attitude adjusting device (2) as a structure for realizing the positioning function. Elevation angle detection circuit (5) and azimuth angle detection circuit (6), elevation angle and azimuth angle detected by both detection circuits (5) and (6), and altitude of two satellites obtained from the demodulation circuit (4) / Positioning calculation circuit to measure the current position of the moving object based on latitude / longitude information (7)
And a memory (8) used for calculation by the positioning calculation circuit (7)
The positioning result (latitude and longitude) is supplied to the video output device (10), and the current position is displayed together with the surrounding map.

FIG. 2 shows a series of steps for realizing the positioning function by the digital radio broadcast receiver according to the present invention. First, in step S1, the antenna attitude adjustment device (2) adjusts the antenna attitude, and in step S2, the demodulation circuit (4) detects altitude / latitude / longitude information. The altitude / latitude / longitude information about the detected two satellites is stored in the memory (8).
Further, in step S3, the elevation angle and the azimuth angle are detected by the elevation angle detection circuit (5) and the azimuth angle detection circuit (6). The detected elevation and azimuth angles for the two satellites are stored in the memory (8), respectively. Then, in step S4, a positioning calculation described later is executed, and in step S5, the current position is displayed on the video output device (10) based on the latitude / longitude information obtained by the positioning calculation, and then the process returns to step S1. And repeat the same procedure.

3 to 5 show the principle of positioning according to the present invention. In the three-dimensional space shown in FIG. 3, when the own position P is represented by latitude X and longitude Y, and the position S of the satellite is represented by latitude x, longitude y, and altitude h, the position P moves toward the satellite position S. The inclination angle θ of the line segment A with respect to the horizontal plane is the elevation angle, and the inclination angle φ of the line segment A ′ obtained by projecting the line segment A on the horizontal plane is the azimuth angle.

As shown in FIG. 4, for two satellites S1 and S2, the altitudes of both satellites are h1 and h2, the latitudes of positions S1 'and S2' at which they are projected on the ground are x1 and x2, and the longitude is y.
1 and y2, and the elevation angles with respect to both satellites are represented by θ1 and θ2, in relation to the satellite S1, the own position is on a locus of a circle with a radius d1 centered on the projection position S1 ′ (x1, y1). Exists, and in relation to the satellite S2, its own position is
It should exist on the locus of a circle of radius d2 centered on the projection position S2 '(x2, y2). The radii d1, d2
Can be calculated by the following equation 1.

[0016]

## EQU00001 ## d1 = h1 / tan .theta.1 d2 = h2 / tan .theta.2 Therefore, as shown in FIG. 5, the intersection points P1 and P2 of the two circles are obtained.
If the coordinate position of is calculated, these two coordinate positions become candidates for the own position.

If the first candidate position P1 of the two candidate positions P1 and P2 is the true own position,
Azimuth angles φ1 ′ and φ2 ′ when the satellites S1 and S2 are observed from the candidate position P1 and the satellites S1 and S2 from the candidate position P2.
The azimuth angles φ1 ″ and φ2 ″ in the case of observing are not coincident with each other (φ1 ′ ≠ φ1 ″, φ2 ′ ≠ φ2 ″), and the candidate position P
The azimuth angles φ1 ′ and φ2 ′ from 1 are the azimuth angle detection circuit (6)
Should agree with the azimuth angles φ1 and φ2 detected by (φ1 ′ = φ1, φ2 ′ = φ2). Therefore, if one of the two candidate positions P1 and P2 that has an azimuth angle that matches or approximates the azimuth angle of the antenna detected for at least one satellite is selected, the latitude / longitude of the candidate position is selected. The information represents the position P (X, Y) of the own device. The positioning calculation circuit (7) in FIG. 1 calculates the position of the own device based on the positioning principle described above.

In the positioning device according to the present invention, as described above, first, two candidate positions P1 and P2 in which the moving body can be located are obtained from the altitude / latitude / longitude information of the two satellites and the elevation angle of the antenna. After that, since the procedure of selecting one candidate position that is the actual position of the moving body based on the azimuth angle of the antenna detected for at least one satellite is adopted, the measurement accuracy of the azimuth angle of the antenna is low. Even in this case, the position of the own device can be measured with high accuracy.

As described above, according to the present invention, high-accuracy positioning using two satellites is possible, so that the circuit configuration does not become complicated, which allows positioning to be provided to the market at low cost. It is possible to realize a satellite digital radio receiver with functions.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a satellite digital radio receiver according to the present invention.

FIG. 2 is a flowchart showing a series of steps for realizing a positioning function by the receiver.

FIG. 3 is a diagram for explaining the relationship between the position of its own device and the position of the satellite.

FIG. 4 is a diagram illustrating a relationship between two satellites and two circles in which the own position may exist.

FIG. 5 is a diagram illustrating a relationship between two candidate positions and azimuth angles.

[Explanation of symbols]

(1) Antenna (2) Antenna attitude adjustment device (3) Tuner (4) Demodulation circuit (5) Elevation angle detection circuit (6) Azimuth angle detection circuit (7) Positioning calculation circuit (8) Memory (9) Audio output device (10) Video output device

Claims (2)

[Claims] 1. A positioning device which is mounted on a mobile body and which receives radio waves sent from two satellites orbiting a predetermined orbit and measures the position of the mobile body, is sent from each satellite. An antenna that receives radio waves, an antenna attitude adjustment means that adjusts the attitude of the antenna in the direction in which the strength of the received radio waves is maximized for each satellite, and the radio waves received by the antenna from each satellite are included. Information detecting means for detecting altitude / latitude / longitude information, antenna angle detecting means for detecting the elevation angle and azimuth angle of the antenna with respect to each satellite adjusted by the antenna attitude adjusting means, and altitude / latitude / latitude / First arithmetic processing means for deriving latitude / longitude information of two candidate positions with respect to the own position based on the longitude information and the elevation angle of the antenna, and at least one of the two candidate positions. And a second arithmetic processing means for selecting one candidate position matching the azimuth angle of the antenna detected for one of the satellites and outputting latitude / longitude information of the candidate position as a positioning result. Positioning device for mobile objects. 2. A first arithmetic processing means obtains two circles defined by altitude / latitude / longitude information of both satellites and an elevation angle of an antenna, and two intersection points where the two circles intersect are the two candidates. The positioning device according to claim 1, which is a position.