JP2008082819A - Positioning instrument and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an independent positioning instrument and an independent positioning method for estimating a receiver position with the effect of a receiver clock error suppressed. <P>SOLUTION: A linear regression equation is formed which has, as object variables, respective input observation values, that is, carrier phases of L1 waves as to respective selected GPS satellites, carrier waves of L2 waves, code pseudo ranges of C/A codes, code pseudo ranges of PY codes, clock error information, ionization layer delay information, and troposphere delay information, and includes integer bias and the receiver position as explanatory variables. On this occasion, receiver bias for every carrier wave signal and that for every code, hitherto included in the clock error, are separated from the clock error and added to the regression equation. A least-squares method is applied to the regression equation to estimate/calculate the integer bias and the receiver position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a positioning device and a positioning method for positioning a receiver using a positioning signal.

  Conventionally, various devices that perform positioning using positioning signals transmitted from positioning satellites have been disclosed, and the basic positioning calculation uses a code pseudorange and a carrier phase difference due to a carrier wave to obtain a three-dimensional receiver. It was obtained by applying Newton's method or extended Kalman filter to the nonlinear simultaneous equations with the position (error) and receiver clock error as unknowns. At this time, in order to remove the error caused by the ionospheric delay and the error caused by the troposphere delay, the influence of these delays is set to “0” from the initial state, or arithmetic processing such as a single phase difference is performed. The amount of delay was estimated.

As a method for solving this, Patent Document 1 discloses that a predetermined parameter including a receiver position to be calculated is an unknown, a regression equation is formed using data that can be observed from a positioning signal, and the regression equation is calculated. Discloses a method for calculating the receiver position.
International Publication No. WO2006 / 022318 A1

  However, in the method disclosed in Patent Document 1, the receiver clock error and the positioning satellite clock error are each handled as one parameter unique to the receiver and the satellite. The error varies depending on the type. Therefore, when the method of Patent Document 1 is used, an error of a certain scale, for example, several tens of centimeters, is generated as the receiver position, and it is difficult to converge further.

  Accordingly, an object of the present invention is to provide a positioning device and a positioning method capable of positioning a receiver position with higher accuracy than before.

  The present invention relates to a satellite clock error for observing a clock error of a positioning satellite from a navigation message included in a positioning signal transmitted by being superimposed on a carrier signal of a plurality of frequencies from a plurality of positioning satellites or a value estimated in advance by offline processing. Detecting means, ionospheric delay information acquiring means for acquiring ionospheric delay information, tropospheric delay information acquiring means for acquiring tropospheric delay information, integer value bias of multiple frequency carrier wave, receiver clock error, and receiver position unknown The receiver position is linearly approximated by expanding the first-order Taylor series with the past estimated calculation value, integer bias, receiver clock error, receiver position, positioning satellite clock error, ionospheric delay information, troposphere Construct a regression equation with the delay information as explanatory variables and the observed carrier phase and code pseudorange as objective variables. And integer bias by applying the least square method to equations, the receiver clock error, the positioning calculation means for estimating the position of the receiver, to a positioning device provided with a. The positioning calculation means of this positioning apparatus is characterized in that at least the receiver clock error is set by dividing it by carrier signal type and code type and substituting it into a regression equation for use.

  Further, the present invention observes a clock error of a positioning satellite from a navigation message included in a positioning signal transmitted by being superimposed on a carrier signal of a plurality of frequencies from a plurality of positioning satellites or a value estimated in advance by offline processing, Acquire ionospheric delay information and tropospheric delay information, include integer bias of multiple frequency carriers, receiver clock error, and receiver position as unknowns, and expand the first-order Taylor series with the estimated calculation values in the past Approximate integer value bias, receiver clock error, receiver position, positioning satellite clock error, ionospheric delay information, and tropospheric delay information as explanatory variables, aiming at observed carrier phase and code pseudorange By constructing a regression equation as a variable and applying the least squares method to the regression equation, an integer value bias, receiver clock error, and reception The present invention relates to a positioning calculation method for estimating and calculating the position of a machine. The positioning calculation method is characterized in that at least the receiver clock error is divided and set for each type of carrier wave signal and each type of code, and is substituted into a regression equation for use.

  In these configurations and methods, when setting the regression equation, the receiver clock error is classified by carrier signal type (for example, L1 wave and L2 wave for GPS) and code type (for example, GPS). If there is, C / A code and P (Y) code) are divided and set. As a result, an unknown calculation value (convergence value) can be obtained with higher accuracy than in the case where a calculation is performed by rounding these practically different errors as one receiver clock error. Since the unknown position includes the receiver position, the receiver position can be obtained with high accuracy.

  Further, the positioning calculation means of the positioning device of the present invention is characterized in that the clock error of the positioning satellite is divided and set for each type of carrier wave signal and for each type of code, and is substituted into a regression equation for use.

  The positioning calculation method of the present invention is further characterized in that the clock error of the positioning satellite is divided and set for each type of carrier signal and for each type of code, and is substituted into a regression equation for use.

  In these configurations and methods, for the satellite clock error, similarly to the receiver clock error, the carrier wave signal type (for example, L1 wave and L2 wave for GPS) and the code type (for example, GPS) If there is, C / A code and P (Y) code) are divided and set. Thereby, the operation value (convergence value) with respect to the unknown of the regression equation can be obtained with higher accuracy. Since the unknown position includes the receiver position and the satellite position, the receiver position and the satellite position can be obtained with high accuracy.

  According to the present invention, it is possible to calculate the unknowns constituting the regression equation with higher accuracy by classifying the receiver clock error in detail for each type and code of the carrier signal and using it in the regression equation. As a result, the receiver position can be measured with higher accuracy.

A positioning device and a positioning calculation method according to an embodiment of the present invention will be described with reference to the drawings. In the following description, GPS is described, but the present invention can be applied to all other GNSS (Global Navigation Satellite System). Moreover, although the following description demonstrates the case where independent positioning is performed, it is applicable also to relative positioning.
FIG. 1 is a block diagram showing a schematic configuration of the single positioning apparatus of the present embodiment.
FIG. 2 is a flowchart showing a processing flow of the single positioning system including the single positioning device and the GPS receiver according to this embodiment.

  As shown in FIG. 1, the single positioning device 10 is connected to a GPS receiver 30 and includes a navigation message analysis unit 11, a satellite information processing unit 12, and a positioning calculation unit 13.

  The GPS receiver 30 is connected to the antenna 20, and from the GPS signal (positioning signal) received from the antenna 20 by a GPS satellite (positioning signal), the carrier phase and C / A code of the L1 wave and L2 wave are known by a known method. And the code pseudo distance (pseudo distance) of P (Y) code is acquired, and the navigation message superimposed on the L1 wave is acquired (S1 → S2). Then, the GPS receiver 30 outputs the navigation message to the navigation message analysis unit 11 of the single positioning device 10, and outputs the carrier phase and the code pseudo distance to the positioning calculation unit 13 of the single positioning device 10.

  The navigation message analysis unit 11 analyzes the input navigation message, acquires ionospheric delay information, clock error and orbit information of each GPS satellite, and acquires tropospheric delay information using a mathematical model (S3). And output to the satellite information processing unit 12.

  The satellite information processing unit 12 selects a GPS satellite to be used for positioning using the ephemeris information of the GPS satellite, and outputs clock delay information, ionospheric delay information, and tropospheric delay information regarding the selected GPS satellite to the positioning calculation unit 13. .

The positioning calculation unit 13 inputs each observation value, that is, the carrier phase of the L1 wave, the carrier phase of the L2 wave, the code pseudo distance by the C / A code, the code of the P (Y) code for each selected GPS satellite Using the pseudorange, receiver clock error information, receiver bias, satellite clock error, ionosphere delay information, troposphere delay information, and applying the least squares method to the linear regression equation described later, an integer bias for the L1 and L2 waves N _L1, N _L2, receiver clock error .DELTA.t _u, conventional receiver clock error .DELTA.t receiver bias was included in the _{u δb CA, u, δb PY} , u, δb L1, u, δb L2, u, the receiver The position u is estimated and calculated (S4). This calculation is repeated until the estimated value changes below a predetermined threshold value, and the estimated calculation result of the receiver position when the estimated value changes reaches the predetermined threshold value is output as the positioning result. Is done.

  Here, the navigation message analysis unit 11, the satellite information processing unit 12, and the positioning calculation unit 13 are each composed of a numerical calculation processor such as a microprocessor that implements the following algorithm. These portions may be formed by a plurality of numerical arithmetic processors or by a single numerical arithmetic processor.

Next, the estimation calculation algorithm for the integer value biases N _L1 and N _L2 and the receiver position u will be described in detail.

In general, the observation equation of the code pseudorange (pseudorange) ρ ^p _{c, u} for the receiver u and the GPS satellite p can be expressed by the equations (1) and (2), _and the observation equation of the carrier phase Φ ^p _{L, u} Is expressed by equations (3) and (4). Here, the multipath error is negligible and ignored.

Here, λ _L indicates the wavelength of the L wave (L1 wave, L2 wave), and r ^p _u (t, t−τ ^p _u ) is the receiver u at time t and the time (t−τ ^p _u ). ΔI ^p _u (t) indicates the ionospheric delay of the L1 wave, δT ^p _u (t) indicates the tropospheric delay of the L1 wave and the L2 wave, and δt _u (t) is true. Represents the clock error of the receiver u at time t, δt ^p (t−τ ^p _u ) represents the clock error of the GPS satellite p at time (t−τ ^p _u ), and δb _{L, u} represents the receiver. u represents the bias for the L wave, δb _{CA, u} represents the bias for the C / A code of the receiver _u , δb _{PY, u} represents the bias for the P (Y) code of the receiver u, and δb ^p _L is shows the bias for L wave of the GPS satellite p, [delta] b ^p _CA represents a bias for C / a code of the GPS satellite p, [delta] b ^p _PY is the GPS satellites p (Y) shows the bias for ^code, _{N p L, u} represents an integer bias between the receiver u and satellite p in L ^{_{wave, ε p L, u (t}} ), e p c, u (t ) Indicates observation noise.

By the way, the distance r ^p _u (t, t−τ ^p _u ) between the receiver and the GPS satellite can be expressed by equation (5).

Next, an a priori estimated receiver position u ^(j) (t) of unknown receiver position u (t) ≡ [x _u (t), _yu (t), z _u (t)] ^T ≡ [x _u ^(j) (t), _yu ^(j) (t), z _u ^(j) (t)] Perform a first order Taylor series expansion around ^T. Furthermore, performing the p-th primary tiller series expansion around priori estimated positioning satellite position se ^p for positioning satellite positions s ^p. Thus, when r ^p _u (t) is linearly approximated, the following equation is obtained.

  here,

When defined as ( _ns is the number of positioning satellites), the equations (1) to (4) are expressed by the following equations (8) to (11).

  This is an approximate linear function with the carrier phase and code pseudorange as objective variables and the receiver position, ionospheric delay, tropospheric delay, receiver bias, GPS satellite bias, integer bias, and error factors as explanatory variables. Corresponds to regression equation.

  Here, since the GPS satellite bias is an element that is about two digits lower than the receiver bias, it is ignored in the following calculation.

  And

If defined, equations (8) to (11) are expressed by the following equations consisting of a vector matrix.

  It is.

  This linear regression equation is repeatedly estimated using the least squares method to converge unknowns and acquire each value. At this time, as the convergence condition of the unknown, the value of the unknown is determined when the change in the estimated value of the unknown reaches a predetermined threshold or less.

Such operations by performing, each carrier signal L1, L2 and the code CA, with the receiver bias [delta] b _u that varies by PY, it is possible to estimate the integer ambiguity _{N L1, N L2} and receiver position u.

As a result, instead of rounding a comprehensive receiver clock error .DELTA.t _u conventional receiver bias [delta] b _u like, by accurately calculate the receiver bias [delta] b _u, at the same time, integer ambiguity N _L1, N _L2 and the receiver position u can be calculated with higher accuracy. For example, the receiver position can be calculated on the order of several centimeters by using the method of the present application.

In the above description, using the receiver bias [delta] b _u in the regression equation was not used GPS satellites bias [delta] b ^p, and the above equation (8) to Formula (11) as it is a matrix representation, the regression equation You may make it use. In this case, since the number of arithmetic processes increases, the time required to calculate the receiver position becomes longer, but the receiver position can be calculated with higher accuracy.

In the above description, all unknowns are estimated by the receiver. However, calculation elements that do not largely depend on the receiver position, such as ionospheric delay amount and tropospheric delay amount, are estimated by the base station and given to the receiver. Also good. Thus, it is possible to calculate the receiver bias bias [delta] b _u and receiver position further highly accurately.

  In the above description, an example in which the least square method is applied to the regression equation is shown, but other parameter estimation algorithms may be used.

  In the above description, single positioning is shown as an example, but the above-described method and configuration can also be applied to relative positioning.

  It is also possible to install two receivers that perform single positioning in the vicinity, measure these distances in advance, use them as constraint conditions, and apply them to the regression equation described above. In this case, the receiver position can be measured with higher accuracy.

The block diagram which shows schematic structure of the single positioning apparatus of embodiment of this invention. The flowchart which shows the processing flow of the single positioning system which consists of the single positioning apparatus and GPS receiver of embodiment of this invention.

Explanation of symbols

10-single positioning device 11-navigation message analysis unit 12-satellite information processing unit 13-positioning calculation unit 20-GPS antenna 30-GPS receiver

Claims (4)

A satellite clock error detecting means for observing a clock error of the positioning satellite from a navigation message included in a positioning signal transmitted by being superimposed on a carrier signal of a plurality of frequencies from a plurality of positioning satellites or a value estimated in advance by offline processing; An ionospheric delay information acquisition unit for acquiring ionospheric delay information, a tropospheric delay information acquisition unit for acquiring tropospheric delay information, an integer value bias of the multiple frequency carriers, a receiver clock error, and a receiver position as unknowns The receiver position is linearly approximated by first-order Taylor series expansion using past estimated calculation values, and the integer bias, the receiver clock error, the receiver position, the positioning satellite clock error, and the ionospheric delay Information, the tropospheric delay information as explanatory variables, and the regression process using the observed carrier phase and code pseudorange as objective variables A positioning apparatus comprising: positioning calculation means for calculating and estimating the integer value bias, the receiver clock error, and the position of the receiver by applying a least square method to the regression equation Because
The positioning calculation means uses at least the receiver clock error divided and set for each type of carrier wave signal and each type of code, and substitutes it into the regression equation for use.   The positioning device according to claim 1, wherein the positioning calculation unit divides and sets the clock error of the positioning satellite according to the type of carrier signal and the type of code, and substitutes it into the regression equation for use. The clock error of the positioning satellite is observed from a navigation message included in a positioning signal transmitted from a plurality of positioning satellites superimposed on a carrier signal of multiple frequencies or a value estimated in advance by offline processing, and ionospheric delay information and troposphere Linearity is obtained by acquiring delay information, including the integer bias of the carrier waves of the plurality of frequencies, the receiver clock error, and the receiver position as unknowns, and expanding the first-order Taylor series of the receiver position with past estimated calculation values. Approximating the integer value bias, the receiver clock error, the receiver position, the positioning satellite clock error, the ionospheric delay information, and the tropospheric delay information as explanatory variables, and the carrier phase and code pseudorange as observation values Is formed as an objective variable, and the integer value bias is applied by applying the least square method to the regression equation. A positioning calculation method for estimating and calculating a receiver clock error and a position of the receiver,
A positioning calculation method in which at least the receiver clock error is divided and set for each type of carrier signal and each type of code, and is substituted into the regression equation for use.   4. The positioning calculation method according to claim 3, wherein the clock error of the positioning satellite is divided and set for each carrier signal type and code type, and is substituted into the regression equation for use.

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