JPH0795093B2 - GPS navigation device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a GPS navigation device that receives a signal from a satellite and calculates and displays the position of a user (moving body).

(Prior Art) A conventional GPS navigation device receives signals from four satellites, demodulates the navigation data, and measures pseudoranges. The navigation data was converted to the satellite position, and the user's position was determined by solving the following equation and solving it.

Here, X ₁ , Y ₁ , and Z ₁ are the positions of the first satellite in the earth-fixed earth center coordinate system, and R ₁ is the pseudorange of the first satellite.

Similarly, X ₂ , Y ₂ , Z ₂ , R ₂ is the second satellite and X ₃ , Y ₃ , Z ₃ , R ₃ is the third satellite.
The satellite, X _4, Y _4, Z _4, R ₄ is the position of the fourth satellite, a pseudo distance. In addition, X, Y and Z are the position of the user, T is the error with respect to the GPS system time of the clock of the user's GPS navigation device, and C is the speed of light.

(Problems to be solved by the invention) Therefore, when a vehicle is equipped with a GPS navigation device and travels in an urban area, a signal from the satellite is blocked by a building or the like, and four or more satellites are in the visible range. Positioning is often interrupted without entering the satellite, and before the GPS system is completed, there is a limit to the time when four or more satellites can be used. was there.

(Means for Solving Problems) The present invention has been made in order to solve such a drawback, and includes a receiving unit that obtains a satellite position and a pseudo range from signals from a plurality of satellites, and a mobile unit. A memory unit that stores a node of a line segment or a curve that approximates the planned runway, and 2 of the line segment or the curve that approximates the runway on which the moving body travels.
A unit for reading the position of a node from the memory unit is provided, and the positions of a plurality of satellites and pseudoranges obtained from the signals from at least two satellites input from the receiving unit are set to the 2
The calculation unit is configured to have a means for calculating the position of the moving body by performing calculation by combining the positions of the nodes.

(Embodiment) FIG. 1 is a block diagram of an embodiment of the present invention.

In the figure, 1 is an antenna unit for receiving satellite signals, 2 is a receiving unit, 3 is a computing unit, 4 is a display unit, 5 is an input unit of a GPS navigation device, and 6 is a memory unit.

Next, the operation will be described.

First, before running the moving body, the planned runway is approximated by a polygonal line based on the information obtained from the map, and the positions of the nodes, the starting points, and the arrival points are read. FIG. 2 shows an example thereof. That is, if A is the departure point and D is the arrival point, the solid line is the runway, and this is approximated by the dotted line, and the node is BC.
The position of D from A is read from the map. When this is input from the input unit 5 of the GPS navigation device, the calculation unit 3 records it in the memory unit 6 after appropriate conversion.

Next, the operation during traveling will be described.

The satellite signal received from the antenna unit 1 enters the receiving unit 2 and performs navigation data demodulation and pseudorange measurement for the two satellites. The navigation data is converted into a satellite position by the calculation unit 3. In addition, considering that the user is on the line connecting the nodes, the following equation can be set and solved to find the position of the user. This is output to the display unit 4.

This equation is for the example of FIG. The above two equations are the equations described above. The three formulas below are line segments AB and B, respectively.
It is an equation of C and CD. Note that X _a , Y _a , Z _a are the positions of A X _b , Y _b , Z
_b , X _c , Y _c , Z _c , X _d , Y _d , Z _d are the positions of B, C, D respectively.

Here, the following three expressions use the first expression when the user is located between AB, the second expression when the user is located between BC, and the third expression when the user is located between CD. However, in the initial state immediately after turning on the power of the device, the initial position is input in advance to perform positioning calculation, and thereafter, the node position of the line segment is read from the memory unit 6 based on the obtained position, and the combination of the above equations is used. Positioning calculation is performed with.

In the above, the method of approximating with a line segment has been described, but other two
It is also possible to use an approximation with a second-order curve or an approximation with a higher-order curve.

Also, instead of key input, the entire map is recorded and the CRT
A map is displayed on the display, and the starting point, nodes, and arrival points are entered using a light pen, or the same track is run in advance at a time when the satellites are arranged, positioning is performed by four satellites, and the positions are recorded in memory. It is also possible to keep it.

(Effects of the Invention) As described above, according to the present invention, positioning can be performed by two satellites. Further, if the method of recording the entire map is used, it is possible to input the traveling route while the moving body is traveling, so that the processing before traveling becomes unnecessary.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of one embodiment of the present invention, and FIG. 2 is a diagram showing a track for showing the operation of the embodiment of FIG. 1 ... Satellite signal receiving antenna part, 2 ... Receiving part, 3 ... Computing part, 4 ... Display part, 5 ... GPS navigation device input part, 6 ... Memory part.

Claims (1)

[Claims] 1. A receiving unit for obtaining satellite positions and pseudoranges from signals from a plurality of satellites, and a memory unit for storing a line segment or a node of a curve approximating a planned running path of a mobile body.
A plurality of positions obtained by the signals from at least two satellites input from the receiving unit are provided, having means for reading from the memory unit the positions of the two nodes of the line segment or the curve that approximates the traveling path of the mobile body. A GPS navigation device, comprising: a satellite position and a pseudorange, and a calculation unit having a unit for calculating the position of a moving body by performing calculation by combining the positions of the two nodes.