JPH11118899A - Positioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an accurate positioning result even while the reception of correction values is interrupted. SOLUTION: A correction-value polynomial approximate extrapolation part 5 calculates a correction value based on position and speed error information and following an approximate polynomial including a rational polynomial adopting the information as independent variables, the information being transmitted from a reference station. A correction value calculated by the correction value polynomial approximate extrapolation part 5 is extrapolated to the distance to a GNSS satellite, calculated by a positioning calculation part 4 on the basis of a signal received from the GNSS satellite. The position, etc., of a mobile body regarding loading is calculated on the basis of the distance to which the correction value is extrapolated.

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. In the present application, an object that can move on or around the earth, such as a ship, a vehicle, and a human, is referred to as a moving object. Carrying by a person is also called “loading”.

[0002]

[Prior art and its problems] GPS (Global Position)
GNSS (Global Navigation)
As shown in FIG. 2, a mobile unit receives a signal transmitted from a GNSS satellite existing in orbit around the earth, and receives information included in the signal, for example, a GNSS signal.
Using the information indicating the orbit of the SS satellite and the information indicating the transmission time of the signal, the distance to the GNSS satellite is obtained in each mobile, and the position of the mobile based on the distance obtained for a predetermined number or more of the GNSS satellites And speed. This procedure performed at each mobile unit is called positioning. As a device for improving the positioning accuracy in the GNSS, positioning is also performed at a reference station whose position is known, and error information indicating a positioning error is generated by comparing the positioning result with the known position. And transmitting the result to each mobile unit, and correcting the positioning result at each mobile unit using this error information. A system realized according to this system is called a DGNSS (Different
ial GNSS).

As an example of DGNSS, a reference station calculates a positioning error of a position and a speed, and transmits error information indicating the obtained positioning error to each mobile unit, and each mobile unit obtains a distance correction value based on the error information. , And the obtained correction value to GNS
There is a configuration in which the position of the moving object is obtained based on the distance extrapolated to the positioning result of the distance to the S satellite and the extrapolated distance. In this configuration, the configuration of the positioning device mounted on each moving body is roughly as shown in FIG.

In FIG. 1, an error information receiving section 1 receives position and speed error information transmitted from a reference station, for example, by FM multiplex broadcast waves. The position error information referred to here is the difference between the position of the own station obtained by the reference station through the positioning calculation and the position of the GNSS satellite obtained based on the received signal, that is, the actual measured value of the distance of the own station where the known value is known. This is information indicating the difference between the difference between the position and the position of the GNSS satellite obtained based on the received signal, that is, the true value of the distance. In addition, the speed error information is information indicating a temporal change amount of the position error information. The correction value linear approximation extrapolation unit 2 uses the following linear approximation formula based on the position and speed error information and the elapsed time from the reference time (the time when the position error information was obtained).

[Mathematical formula-see original document] A correction value relating to the distance to the GNSS satellite is obtained according to the following equation: correction value = position error information + speed error information × elapsed time. This linear approximation formula is, for example, the United States Radio Technical
Issued by Commission For Maritime Service (RTCM): “RTCM R
ECOMMENDED STANDARDS FOR DIFFERENTIAL NAVSTAR GPS
SERVICE ", Version 2.1, Jan. 3, 1994, page 4 to page 7. On the other hand, the satellite signal
Upon receiving a signal transmitted from the satellite, the positioning calculation unit 4 obtains a distance to the GNSS satellite based on the signal with respect to a predetermined number or more of the GNSS satellites, and obtains a position of the moving object to be mounted based on the obtained distance. When deriving a position or the like based on the derived distance, the positioning calculation unit 4 adds (extrapolates) the correction value obtained by the correction value linear approximation extrapolation unit 2 to the derived distance.

In such a configuration, there is a problem that the above-described linear approximation formula does not accurately represent the time change of the actual distance positioning error. For example, in GPS, an operation called SA (Selective Availability) that intentionally degrades positioning accuracy is performed by an operating authority, and a distance positioning error component caused by this SA does not change linearly with time. This change is a non-linear change that can be represented by a sinusoidal irregular wave having a period of about three minutes. Therefore, if the above-mentioned linear approximation formula is used, the correction value will not be sufficiently accurate.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to realize a positioning device that can derive a more accurate correction value than in the past and can obtain a more accurate positioning result. In order to achieve such an object, in the present invention, a correction value polynomial approximation extrapolation unit is provided instead of the correction value linear approximation extrapolation unit. That is, a correction value used for correcting the distance by the positioning calculation unit is determined according to an approximate polynomial approximating a non-linear change in the positioning error of the distance with the passage of time. As an example of the approximate polynomial, a polynomial including a rational polynomial having position and velocity positioning errors and time as its independent variables can be cited.

By doing so, in the present invention, even in a system in which a non-linear change in the distance positioning error with the passage of time can appear due to SA or the like, accurate positioning can be performed by eliminating the influence. It is possible to do. DGP
In the example of S, positioning accuracy of about several tens cm can be realized.

[0008]

FIG. 1 shows the configuration of a positioning device according to an embodiment of the present invention. In this embodiment, a correction value polynomial approximation extrapolation unit 5 is provided in place of the correction value linear approximation extrapolation unit 2 in the above-described conventional technology. The correction value polynomial approximation extrapolation unit 5 is based on the distance and speed error information from the reference station and the elapsed time received by the error information receiving unit 1 and based on the approximation polynomial approximating the change in the positioning error of the distance with the passage of time. , A correction value to be supplied to the positioning calculation unit 4, that is, a correction value used for correcting the distance is adopted. Therefore, according to the present embodiment, SA in GPS
As described above, even when operation is performed that causes a non-linear change in the distance positioning error with respect to time, the positioning result finally obtained by the positioning calculation unit 4 is accurate. be able to. Therefore, in a state where signal reception from the reference station is likely to be interrupted by a surrounding building or the like, such as a vehicle traveling in a building, a high positioning result is continuously provided even while reception of the correction value is interrupted, and reception of the correction value is also performed. It is possible to prevent a step-like variation in the positioning result from appearing when restarting. The form of the approximation polynomial employed in the present embodiment may be a polynomial including a rational polynomial having the position and velocity error information and the elapsed time as independent variables. One example is

(Equation 2) There is.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a positioning device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conceptual configuration of DGNSS.

FIG. 3 is a block diagram illustrating a configuration of a positioning device according to one related art.

[Explanation of symbols]

1 Error information receiving unit, 3 satellite signal receiving unit, 4 positioning calculation unit, 5 correction value polynomial approximation extrapolation unit.

Claims (2)

[Claims] A satellite signal receiving unit for receiving a signal including information indicating its orbit and information indicating a transmission time from a GNSS satellite, determining a distance to a transmission source GNSS satellite based on the received signal, and determining a distance equal to or more than a predetermined number. A positioning calculation unit for determining the position of the mobile unit on the basis of the distance determined for the GNSS satellite, and positioning of the position and velocity detected by the reference station based on signals received from a predetermined number or more of GNSS satellites and the known position of the reference station An error information receiving unit that receives the error as error information from the reference station; and a correction value extrapolation unit that obtains a correction value for the distance based on the received error information and corrects the distance obtained by the positioning calculation unit according to the correction value. When,
In the positioning device mounted on the moving body, the correction value extrapolation unit obtains the correction value according to an approximation polynomial approximating a non-linear change of the positioning error of the distance with time. Characteristic positioning device. 2. The positioning device according to claim 1, wherein said approximate polynomial is a polynomial including a rational polynomial having position and velocity positioning errors and time as independent variables.