JP2010216822A - Device for measurement of attitude - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the accuracy of attitude measurement, even if an inter-antenna distance is shortened. <P>SOLUTION: In a data table 14, data are stored which are previously found on coupling errors and classified by incoming directions of signals in a movable-body coordinate system from respective satellites on each of antennas. Data on the coupling errors corresponding to the incoming directions are acquired from the data table 14 by an error acquisition unit 15. By an attitude calculation unit 17, the attitude of a vessel is calculated by using a single phase difference or a double phase difference with the coupling errors removed therefrom. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an attitude measurement device that measures the attitude of a moving body.

  The background technology for measuring the posture of such a moving body will be described step by step.

(1) Definition of posture in moving body First, two coordinate systems, a local coordinate system and a moving body coordinate system are defined as follows. The “local coordinate system” is a right-handed orthogonal coordinate system in which the xy plane is parallel to the horizontal plane and the x-axis is directed to true north at the position of the moving body. The “moving body coordinate system” is a right-handed orthogonal coordinate system fixed to the moving body.

  When defined in this way, the azimuth, pitch, and roll indicating the posture of a moving body such as a ship can be expressed as follows.

  “Direction” is an angle formed from the x-axis of the local coordinate system to the projection onto the xy plane of the local coordinate system of the x-axis of the moving object coordinate system.

  “Pitch” is an angle formed by projection of the local coordinate system of the mobile object coordinate system on the xy plane to the x axis of the mobile object coordinate system.

  The “roll” is a rotation angle from the horizontal plane of the local coordinate system of the y-axis of the moving object coordinate system around the x axis of the moving object coordinate system.

(2) Device Configuration Example of Moving Body Posture Measuring Device Next, FIG. 1 shows a device configuration example of a moving body posture measuring apparatus that measures the posture of a moving body composed of the azimuth, pitch, and roll expressed as described above. This will be described with reference to FIG.

  This moving body attitude | position measuring apparatus 1 is installed in the ship S as an example of a moving body. The moving body posture measuring apparatus 1 includes an antenna unit 2 and a processing unit 3.

The antenna unit 2 includes antennas α, β, and γ, and the antenna α is a reference antenna. The antennas α, β, and γ are assumed to be installed on the ship S. As shown in FIG. 1, it is assumed that the x axis of the moving body coordinate system coincides with the first base line b _αβ formed by the antennas α and β, and the xy plane of the moving body coordinate system is created by the antennas α, β, and γ. It is assumed to be in a plane.

  The processing unit 3 includes three receivers 4 and an attitude calculation processor 5. Each receiver 4 is connected to each antenna α, β, γ, and receives satellite signals (such as GPS signals) received by each antenna α, β, γ. Thereby, in each receiver 4, the carrier wave phase of the received satellite signal and the line-of-sight direction vector (indicating the positional relationship between the satellite and the ship S) to the satellite in the local coordinate system are obtained. Here, the distance between the antennas α, β, and γ is relatively short (for example, about 1 meter), and therefore, the line-of-sight direction vectors from the antennas α, β, and γ with respect to the satellite are all the same. . The attitude calculation processor 5 performs an operation for calculating the attitudes of the antennas α, β, and γ based on the information obtained from each receiver 4.

(3) General attitude calculation method When the mobile body attitude measurement device 1 calculates a baseline vector between the antennas α, β, and γ using a satellite navigation system, the attitude of the ship S is calculated from the calculated value. can do.

………（１）
と表すことができる。 As shown in FIG. 1, if the first base line from the antenna α to β is b _αβ and the second base line from the antenna α to γ is b _αγ , the base line b _αβ , b _αγ Attitude, ie, bearing, pitch, roll,

……… (1)
It can be expressed as.

………（２）
である。なお、数１において、arg(・)は複素数の偏角を求める関数であり、添え字ｘ,ｙ,ｚは、ベクトルの座標系における各軸方向の成分を意味する。 here,

……… (2)
It is. In Equation 1, arg (·) is a function for obtaining the argument of a complex number, and subscripts x, y, and z mean components in the respective axis directions in the vector coordinate system.

(4) Calculation of Baseline Vector As described above, the attitude of the ship S can be calculated by obtaining the baseline vector. Here, the base line vector is obtained as follows.

  First, a single phase difference and a double phase difference are obtained from the carrier phase obtained from the receiver 4. Here, the “single phase difference” is the difference in the carrier phase of the signal from the same satellite at the reference antenna (antenna α) and the user antenna (antennas β and γ), and the “double phase difference” It is the difference between the single phase difference for the reference satellite and the single phase difference for other satellites.

  From the relationship between the single phase difference or double phase difference and the line-of-sight direction vector to the satellite, the base line vector can be calculated using the least square method.

(5) Relationship between Baseline and Single Phase Difference or Double Phase Difference Referring to FIG. 3, the single phase difference is a difference between carrier phases of signals from the same satellite 105 in the reference antenna 101 and the user antenna 102. . Between this difference and the baseline vector constituted by the reference antenna 101 (the signal is received by the reference receiver 103) and the user antenna 102 (the signal is received by the reference receiver 104), there is a path difference.

………（３）
が成り立つ。なお、ｙは位相差、ｈは衛星への単位方向ベクトル、ｂは基線ベクトル、ａは整数の値、Δｔは受信機の位相差の取得タイミングのズレを表す時計誤差、ｅは観測誤差、であり、これらのｙ，ｂ，ａ，Δｔ，ｅの単位は波数とする。また、添え字ｓは一重位相差についての値であることを意味する。

……… (3)
Holds. Here, y is a phase difference, h is a unit direction vector to the satellite, b is a base line vector, a is an integer value, Δt is a clock error indicating a deviation in the acquisition timing of the phase difference of the receiver, and e is an observation error. Yes, the unit of these y, b, a, Δt, and e is the wave number. The subscript s means a value for a single phase difference.

This equation indicates that there is a difference between the single phase difference and the path difference h ^T _s b by the sum of an integral multiple of a certain wavelength and Δt. For example, when the instantaneous phase is observed with each antenna, the range of the value is [−0.5: 0.5]. At this time, since the value of the single phase difference is expressed only by [−1.0: 1.0], the difference between the integral multiple of a certain wavelength and Δt is added to the path difference h ^T _s b. There will be only a difference. This integer value is called the integer ambiguity corresponds to a _s in equation (3).

………（４）
と表される。 The double phase difference is a difference between a single phase difference of a reference satellite and a single phase difference other than the reference satellite at a certain baseline. The relationship between the double phase difference and the baseline in the reference satellite i and satellite k is

……… (4)
It is expressed.

………（５）
を意味する。なお、添え字ｄは二重位相差に関する値であることを表している。二重位相差を用いる利点は、時計誤差を打ち消すことができることである。 here,

......... (5)
Means. Note that the subscript d represents a value related to the double phase difference. The advantage of using a double phase difference is that the clock error can be canceled out.

(6) Calculation of Baseline If a plurality of satellites are received, simultaneous equations relating to the baseline vector b can be established, and the baseline vector b can be calculated by solving these simultaneous equations by the method of least squares.

………（６）
と表される。 For a single phase difference, the simultaneous equations are

……… (6)
It is expressed.

………（７）
である。 here,

......... (7)
It is.

………（８）
と推定できる。 If the integer ambiguity is known, the baseline and clock error can be calculated using the least squares method,

......... (8)
Can be estimated.

………（９）
と設定するのが普通である。ここでσ^２は規格化係数である。 Where Q is a weight matrix,

......... (9)
It is normal to set. Here, σ ² is a normalization coefficient.

………（１０）
と表され、整数値アンビギュイティが既知であるとすれば、基線と時計誤差の推定値ｂ（ｂにハット）は、

………（１１）
と求めることができる。 In the case of double phase difference, the same equation can be solved.

……… (10)
If the integer ambiguity is known, the baseline and clock error estimate b (hat to b) is

……… (11)
It can be asked.

  The integer value ambiguity can be solved by using the well-known LAMBDA method or the method disclosed in Patent Document 1.

JP 2008-64555 A

When measuring the posture of the moving body, the measured posture includes an error. The cause of this error is an error mixed in the measured value of the carrier phase of each antenna. The error e can be divided into error takes a value determined in accordance with the direction of arrival of satellite signals (coupling error, etc.) and e _c other and the error e _other in the mobile coordinate system.

………（１２）
である。 That is,

......... (12)
It is.

  A typical error determined according to the arrival direction of the satellite signal in the moving object coordinate system is an error (coupling error) generated when the antennas interfere with each other.

The distance between the antennas is long, depending on when the longer length of the base line, coupling error e _c is sufficiently small and can be neglected.

However, the distance between the antennas is short, when the short length of the base line, coupling error e _c becomes large, therefore, there is a problem that errors contained in the measurement posture also becomes not negligible increase.

  It is an object of the present invention to improve the accuracy of measuring the attitude of a moving object when an error such as a coupling error that takes a value determined according to the arrival direction of a satellite signal in the moving object coordinate system occurs. Is to do.

  (1) The present invention relates to a plurality of antennas provided on a moving body, carrier phase observation means for observing a carrier phase value of each satellite from a received signal of the antenna, and a moving body coordinate system from the received signal of the antenna. A signal arrival direction calculating means for calculating the arrival direction of each satellite signal; and a phase for acquiring a carrier phase error corresponding to the arrival direction of the signal in the mobile coordinate system calculated by the signal arrival direction calculating means for each satellite. Calculate the attitude of the moving body from the received signal of the antenna using an error acquisition means and a value obtained by subtracting the carrier phase error acquired by the phase error acquisition means from the carrier phase observation value observed by the carrier phase observation means A posture calculation unit.

  (2) Viewed from another aspect, the present invention provides a plurality of antennas provided on a moving body, carrier phase observation means for observing the carrier phase value of each satellite from the received signal of the antenna, and the received signal of the antenna Signal arrival direction calculation means for calculating the arrival direction of each satellite signal in the mobile coordinate system from the carrier, and a carrier wave corresponding to the arrival direction of the signal in the mobile coordinate system calculated by the signal arrival direction calculation means for each satellite Using a phase error acquisition unit that acquires a phase error, and a value obtained by subtracting the phase difference error of the carrier phase error acquired by the phase difference error acquisition unit from the phase difference of the carrier phase observation value observed by the carrier phase observation unit And an attitude calculation unit that calculates an attitude of the moving body from a reception signal of the antenna.

(3) In this case, it further comprises a general posture acquisition means for acquiring a rough value of the posture of the moving body,
The signal arrival direction calculation means may calculate the arrival direction of the satellite signal in the mobile coordinate system based on the approximate attitude value.

  (4) storage means for storing an error corresponding to each arrival direction of the satellite signal in each satellite, and the phase error acquisition means is configured to calculate each of the satellites calculated by the signal arrival direction calculation means. The carrier phase error corresponding to the direction of arrival may be acquired from the storage means.

  According to the present invention, it is possible to correct an error that takes a value determined according to the arrival direction of a satellite signal in a moving object coordinate system, such as a coupling error, and accurately determine the attitude of the moving object.

It is a conceptual diagram of the state which has arrange | positioned the mobile body attitude | position measuring apparatus which is one embodiment of this invention to the hull. It is a block diagram explaining the structure of the process part of the mobile body attitude | position measuring apparatus which is one embodiment of this invention. It is explanatory drawing of a single phase difference. It is explanatory drawing explaining the arrival direction of a satellite signal. It is a functional block diagram of the attitude | position calculation processing machine of the mobile body attitude | position measuring apparatus which is one embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described. Hereinafter, a coupling error will be described as an example of an error that takes a value determined according to the arrival direction of the satellite signal in the moving body coordinate system.

  Here, first, the feature of the coupling error will be described.

Coupling errors e _c is characterized in that takes a value determined for each direction of arrival of satellite signals in the mobile coordinate system for each antenna. That is, a coupling error in the arrival direction (azimuth angle η, elevation angle ζ) of the satellite signal in the moving body coordinate system for the antenna i can be expressed by a function ec _{-Ant (i)} (η, ζ) (see FIG. 4).

  Therefore, the error of the single phase difference due to the coupling error in the base line k composed of the antennas i and j is determined for each arrival direction of the satellite signal,

………（１３）
と表すことができる。すなわち、ｅ_{ｃ（ｓ）-ｂ（ij）}（η，ζ）は基線ｋにおけるカップリング誤差による一重位相差の誤差である。

……… (13)
It can be expressed as. That is, ec _{(s) −b (ij)} (η, ζ) is a single phase difference error due to a coupling error at the base line k.

………（１４）
と表すことができる。すなわち、ｅ_ｃ(d)-b(ij)（η_Ａ，ζ_Ａ，η_Ｂ，ζ_Ｂ）は、基線ｋ、衛星到来方向が方位角η_Ａ、仰角ζ_Ａと方位角η_Ｂ、仰角ζ_Ｂの２衛星から算出される二重位相差の誤差である。 Further, the error of the double phase difference calculated from the two satellites of the base line k, the satellite arrival direction is the azimuth angle η _A , the elevation angle ζ _A and the azimuth angle η _B , and the elevation angle ζ _B is

……… (14)
It can be expressed as. That is, ec _{(d) -b (ij)} (η _A , ζ _A , η _B , ζ _B ) is the base line k, the satellite arrival direction is the azimuth angle η _A , the elevation angle ζ _A and the azimuth angle η _B , and the elevation angle ζ _This is an error of the double phase difference calculated from the two satellites _B.

The values such as the coupling error ec _{-Ant (i)} (η, ζ) and the single phase difference error ec _{(s) -b (ij)} (η, ζ) are obtained by measuring or analyzing antenna characteristics. be able to. Further, the error ec _{(s) -b (ij)} (η, ζ) of the single phase difference can be _{calculated by calculating the} double phase difference if the coupling error _{ec- Ant (i)} (η, ζ) is known. The error ec _{(d) -b (ij)} (η _A , ζ _A , φ _B , ζ _B ) is the coupling error ec _{-Ant (i)} (η, ζ) or single phase difference error ec _{(s ) −b (ij)} (η, ζ) can be obtained respectively.

  Next, an attitude measurement apparatus using such a coupling error feature will be described.

  1 and 2 are explanatory diagrams of the posture measuring apparatus according to the present embodiment.

  The posture measuring device 1 is installed on a ship S as an example of a moving body. The attitude measurement device 1 includes an antenna unit 2 and a processing unit 3.

The antenna unit 2 includes antennas α, β, and γ, and the antenna α is a reference antenna. The antennas α, β, and γ are assumed to be installed on the ship S. As shown in FIG. 1, the x axis of the moving body coordinate system coincides with the first base line b _αβ formed by the antennas α and β, and the xy plane of the moving body coordinate system is created by the antennas α, β, and γ. It shall coincide with the plane.

  The processing unit 3 includes three receivers 4 and an attitude calculation processor 5. Each receiver 4 is connected to each antenna α, β, γ, and receives satellite signals (such as GPS signals) received by each antenna α, β, γ. Thereby, in each receiver 4, the carrier wave phase of the received satellite signal and the line-of-sight direction vector (indicating the positional relationship between the satellite and the ship S) to the satellite in the local coordinate system are obtained. Further, the attitude calculation processor 5 performs an operation for calculating the attitudes of the antennas α, β, and γ based on information obtained from each receiver 4.

  Next, processing executed by the attitude calculation processor 5 will be described.

  FIG. 5 is a functional block diagram illustrating processing executed by the attitude calculation processor 5.

  The processing executed by the attitude calculation processor 5 is executed by the microcomputer based on a predetermined program.

  First, in order to know the arrival direction of the satellite signal, it is necessary to know the general attitude of the ship S. This general posture is defined as (ψ ′, θ ′, φ ′). The approximate attitude data includes (1) the attitude of the ship S calculated without correcting the coupling error, (2) the attitude calculated last time (when the attitude is considered to have not changed much from the previous calculation), (3) It is conceivable to use posture data such as the current posture predicted by complementing the posture measured last time using a vibration gyroscope or the like.

  In this example, at the initial activation of the attitude measurement device 1, the attitude of the ship S calculated without correcting the coupling error by the approximate attitude calculation unit 11 is used, and then the coupling error is calculated by the attitude calculation unit 17 described later. When the corrected attitude data of the ship S is calculated, the attitude data is held in the storage unit 12 and the attitude data obtained by the previous attitude calculation unit 17 is used. Yes. The attitude calculation unit 17 calculates the attitude data of the ship S based on the reception signal of the receiver 4 without correcting the coupling error by the above-described means.

  Next, the satellite arrival direction calculation unit 13 receives signals from the satellites in the moving body coordinate system based on the approximate postures (ψ ′, θ ′, φ ′) obtained from the posture calculation unit 17 or the storage unit 12. The direction (azimuth angle η, elevation angle ζ) is obtained.

………（１５）
から、

………（１６）

………（１７）
と求められる。 This is a coordinate transformation matrix T (ψ, θ, φ) from the local coordinate system to the moving body coordinate system when the line-of-sight direction vector h to the satellite in the local coordinate system is the posture (ψ ′, θ ′, φ ′). The line-of-sight direction vector h ′ to the satellite in the moving body coordinate system obtained using

……… (15)
From

……… (16)

……… (17)
Is required.

とあらわされる。 Here, the coordinate transformation matrix T (ψ, θ, φ) from the local coordinate system to the moving body coordinate system is

It is expressed.

  The data table 14 stores coupling error data for each arrival direction (azimuth angle η, elevation angle ζ) in the moving body coordinate system of the signal from each satellite for each antenna obtained in advance.

  The error acquisition unit 15 receives, from the data table 14, coupling error data corresponding to the arrival direction (azimuth angle η, elevation angle ζ) in the moving object coordinate system of the signal from each satellite obtained from the generation arrival direction calculation unit 13. get. The acquisition of the coupling error data may be obtained by calculation using a predetermined function.

  The phase difference calculation unit 16 obtains the single phase difference or the double phase difference from the coupling error obtained by the error acquisition unit 15 in a form excluding the coupling error as described above.

  Then, the attitude calculation unit 17 calculates the attitude of the ship S using the single phase difference or the double phase difference excluding the coupling error and the satellite signal. The calculated posture data is output to the outside and stored in the storage unit 12 for use in the calculation of the next posture.

  According to the attitude calculation device 1 described above, the coupling error is determined in advance by taking a predetermined value with respect to the arrival direction of the signal in the moving body coordinate system centered on the antennas α, β, and γ. Even if the distance between antennas α, β, and γ is shortened by using the coupling error that has been obtained (or calculated by a predetermined function) and measuring the posture by subtracting the error. It is possible to calculate an accurate posture without coupling error.

  In the above description, the coupling error has been described as an example, but the present invention is not limited to this, and an error that takes a value determined according to the arrival direction of the satellite signal in the mobile coordinate system, By removing this by the same process as described above, the accurate posture of the moving body can be calculated.

DESCRIPTION OF SYMBOLS 1 Attitude calculation apparatus 11 Approximate attitude calculation part 12 Storage part 13 Satellite arrival direction calculation part 14 Data table 15 Error acquisition part 16 Phase difference calculation part 17 Attitude calculation part S Ship α, β, γ Antenna

Claims (4)

A plurality of antennas provided on a moving body;
Carrier phase observation means for observing the carrier phase value of each satellite from the received signal of the antenna;
Signal arrival direction calculation means for calculating the arrival direction of each satellite signal in the moving body coordinate system from the received signal of the antenna;
Phase error acquisition means for acquiring a carrier phase error corresponding to the arrival direction of the signal in the mobile coordinate system calculated by the signal arrival direction calculation means for each satellite;
Attitude calculation means for calculating the attitude of the moving body from the received signal of the antenna using a value obtained by subtracting the carrier phase error acquired by the phase error acquisition means from the carrier phase observation value observed by the carrier phase observation means; ,
An attitude calculation device comprising: A plurality of antennas provided on a moving body;
Carrier phase observation means for observing the carrier phase value of each satellite from the received signal of the antenna;
Signal arrival direction calculation means for calculating the arrival direction of each satellite signal in the moving body coordinate system from the received signal of the antenna;
Phase error acquisition means for acquiring a carrier phase error corresponding to the arrival direction of the signal in the mobile coordinate system calculated by the signal arrival direction calculation means for each satellite;
Using the value obtained by subtracting the phase difference error of the carrier phase error acquired by the phase difference error acquisition unit from the phase difference of the carrier phase observation value observed by the carrier phase observation unit, the received signal from the antenna is used. Attitude calculating means for calculating the attitude;
An attitude calculation device comprising: A rough posture acquisition means for acquiring a rough value of the posture of the moving body;
The signal arrival direction calculation means calculates the arrival direction of the satellite signal in the mobile coordinate system based on the approximate attitude value.
The posture calculation apparatus according to claim 1 or 2. Storage means for storing an error corresponding to each arrival direction of the satellite signal in each satellite;
The phase error acquisition means acquires from the storage means the carrier phase error corresponding to each arrival direction calculated by the signal arrival direction calculation means for each satellite.
The posture calculation apparatus according to claim 3.

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