JPS62882A - Navigation system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a navigation device using GPS, and particularly to a device that prevents deterioration of positioning accuracy due to blocking.

[Technical background of the invention and its problems]

GE'S will be explained. GPS is a new worldwide satellite navigation system being developed by the U.S. Department of Defense.
It is a satellite navigation system that allows you to find the CLJ output with the accuracy of Shimako at any time, no matter where you are in the world.

The satellite has an orbital inclination of 55° with respect to the equator and an altitude of approximately 20,000 K.
It has a circular orbit of m, and is made up of 21 satellites in total, including 18 satellites, three each placed on six orbital planes, and three spare satellites.

Satellites are arranged so that four or more satellites are always visible anywhere on the earth.

The principle by which the three-dimensional position of a user is determined using GPS will be described below. As shown in FIG. 2, GPS satellites have accurate clocks and transmit satellite position information and time.

Users are less accurate than clocks on board satellites.
and has a clock that is not synchronized with the clock on the satellite,
Using this clock, for example, the position information of the satellite i < i = 1.2.3.4 transmitted at time t3 is received, and the user's time tui at that time is determined. The distance fi between the satellite i and the user is determined from this tui and ts. This fi includes the user's clock error Δtu, so if the true distance between the user and the satellite i is Ri, then the following formula holds, C(tu i- tS)=Ri=Ri+Δt u
C(1)C; Light! i = 1. 2. 3. 4. In this equation, the difference Δtu between the user's longitude, latitude, altitude and the clock is an unknown quantity. Since there are 4 unknowns, if we lengthen the above pseudo distance 1 for 4 satellites, the user's 3
The dimensional position is determined.

A GPS receiver that receives radio waves from this GPS satellite,
When mounted on a moving object such as a car and used in a city with many high-rise buildings, blocking occurs where the desired satellite is hidden behind buildings such as buildings, resulting in deterioration of positioning accuracy and inability to perform positioning. This phenomenon occurs.

FIG. 3 shows a diagram where blocking occurs.

As described above, in order to determine the three-dimensional position of a moving object, the GPS receiver needs to capture four GPS satellites.

As shown in FIG. 3, satellites 30.31.32. The satellite 33 can be captured because the wave directly arrives, but the satellite 33
I can't catch it because it's hidden behind it.

In this way, 311! The conventional positioning method used when the user's watch could only detect G satellites.
Thinking that it coincided with the PS time, positioning was performed with the unknown value Δtu set to zero.

Since the user clock has a long-term stability of 1O-6/year, Δtu increases as time passes, causing deterioration in positioning accuracy that cannot be used for automobiles. Another conventional method used a barometric altimeter to provide known altitude. The accuracy of the barometric altimeter is ±50m or more, so high-precision lateral positioning is not possible.

[Purpose of the invention]

The present invention has been made in view of the above points, and utilizes a GPS system that can be captured by a car navigation system.
If the number of Eri is less than 3, the height and information are read out from the device that records map information, and the GPS user's 3
The purpose of this invention is to provide a navigation device that determines dimensional position.

[Summary of the invention]

The present invention is an automotive navigation device using GPS, when the number of captured GPS is 3 or less using a GPS receiver and a device that records map information including height information.
The present invention provides a device that uses height information recorded in the map recording device to determine the three-dimensional position of a GPS user.

〔Effect of the invention〕

Prevents deterioration of positioning accuracy due to blocking and ensures positioning accuracy that is sufficient for automotive navigation. Eliminates deterioration in positioning accuracy of conventional methods due to the use of %K altimeters and oscillators with low frequency stability. .

[Embodiments of the invention]

An embodiment of the present invention is shown in FIG.

The present invention comprises an antenna 5, a GPS receiver 6, a device 7 for determining the user's three-dimensional position and time, a device 8 for monitoring the number of satellites captured by the GPS receiver, and the user's position and map. It consists of a display 9 for displaying the map 1111, a map 1111, and a 11-year-old magazine 10.

This will be explained below with specific examples.

A case will be described in which the number of captured satellites is three.

The GB8 satellite has a circular orbit with an inclination angle of 550 with respect to the equator and an altitude of about 20,000 km, and consists of 18 flii placed three on each of six orbital planes.

Even in places on earth, where there are no obstacles such as buildings, satellites of 4f11 or larger are always visible. , a GPS receiver 6 performs RF-IP conversion, frequency despreading, and demodulation, and sends the demodulated signal to a device 7 for determining the three-dimensional position and time of the user.

The signal is divided into two, and one side is equipped with a device that monitors the number of captured satellites.
Send to 8.

First, the device 18 moves the mobile body so that the number of captured satellites becomes four. After securing 41-, the device for determining the user's three-dimensional position and time @7 solves the equation given by equation (l) to determine the user's position O Device that records map information The map information is read out from IO, the map is displayed on the display device 9, and the user's position determined above is also displayed.

Plane map information and height information are recorded in the device 10. Here, it is assumed that heights are recorded at 5 m intervals as height information.

FIG. 4 shows an example of a map displayed on the display device 9. If you can capture the four GPS satellites shown above,
Assign the requested position to a person. Continuing to capture 4 satellites/
Assume that the trajectory when the moving object moves to i\B is 51.

At this time, it can be seen that the height of the user's position B is 7 m.

Further, equation 11) can be transformed into the following equation.

+CΔt u (2)(t
i, yi, Zi)...Constellation image of the i-th satellite...
Known X, y...Horizontal direction position 91', Z...Height direction position In equation (2), (Xi, Yis Zi) is i
The position of the th satellite is known because its orbit is known in advance, (X, ySz) is the user's position and O is the height. Point B is Z=7m.

Next, at point B, the number of captured satellites is reduced to 3 due to the shadows of buildings in the city, etc.
Suppose that it becomes an individual. From the output of the GPS receiver 6, the device 8 can detect that the number of captured satellites has become three.

In this state, when the moving object is moving towards 01, distance measurement is performed by sending the information of Z = 7m from the device flIlo to the device 7, taking 2 of equation (2) as known, and x1ySΔtU as an unknown quantity, and calculating the distance using three It is possible to determine the ffi for the acquired satellite and determine the three-dimensional position of the user. When this positioning method is performed, values in the vicinity of the actual position ff1ct of the moving object are obtained, and the position (Xi, yct) on the plane is determined. The height information at the point (Xcl, Ycl) is
It can be found from 0.

Next, the height information at this CI is substituted into 2, and positioning is performed. As a result, the plane position t (X't XY
c,) can be found. Positioning can be performed by repeating this process.

When the number of captured satellites reaches 4@, positioning is performed using information from 4 satellites. As a result, D.

When the position is correct, a light is displayed on the display device.

Furthermore, if four GPS satellites can be captured, it is also possible to compare the three-dimensional position obtained from 10 PS satellites and the position obtained using map information. The number of captured satellites is 2Il! In this case, it is also possible to perform positioning by assuming that Z and X or Y in equation (2) are known.

As described above, by using the present invention, deterioration of positioning accuracy due to blocking can be prevented, and positioning accuracy that is sufficiently applicable to automobile navigation can be ensured.

Eliminates the deterioration in positioning accuracy caused by the use of barometric altimeters and launchers with low frequency stability.

Further, the height may not be displayed on the display device 9.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing an embodiment of the present invention.
FIG. 3 is a diagram showing the iIR principle of the PS, FIG. 3 is a diagram showing blocking within a city, and FIG. 4 is a diagram showing the operation of the present invention. 1 to 4...GPS satellite 5...Antenna 6...GPS receiver 7...Device 8 for determining the user's three-dimensional position and time・Device 9 for monitoring the number of captured satellites...
・Display device 10... Device 30-3 that records map information
3... GPS satellite 34... Building 35... Mobile object

Claims (1)

[Claims] It is equipped with a GPS receiver, a device that records map information including height information, and a device that displays this map information, and uses the height information recorded in the map recording device to
A navigation device characterized by determining a three-dimensional position of a PS user and displaying this on the map display device.