CN113848579B - Coarse error elimination method and system for INS assisted GNSS positioning - Google Patents

Coarse error elimination method and system for INS assisted GNSS positioning Download PDF

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CN113848579B
CN113848579B CN202111439101.5A CN202111439101A CN113848579B CN 113848579 B CN113848579 B CN 113848579B CN 202111439101 A CN202111439101 A CN 202111439101A CN 113848579 B CN113848579 B CN 113848579B
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gnss
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CN113848579A (en
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张伟
于洪涛
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Beijing Beidou Huada Technology Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/42—Determining position
    • G01S19/48—Determining position by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system
    • G01S19/49—Determining position by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system whereby the further system is an inertial position system, e.g. loosely-coupled
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C21/00—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
    • G01C21/10—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration
    • G01C21/12—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning
    • G01C21/16—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
    • G01C21/165—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation combined with non-inertial navigation instruments
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/35—Constructional details or hardware or software details of the signal processing chain
    • G01S19/37—Hardware or software details of the signal processing chain
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/393—Trajectory determination or predictive tracking, e.g. Kalman filtering

Abstract

The embodiment of the invention discloses a gross error rejection method and a gross error rejection system for INS assisted GNSS positioning, wherein the method comprises the following steps: step 1: acquiring GNSS observation value data of the current time; step 2: estimating the state of the GNSS Kalman filter according to the previous GNSS positioning result; and step 3: eliminating pseudorange observation value gross errors and eliminating Doppler observation value gross errors; and 4, step 4: setting observation value noise according to the tracking state, channel noise, carrier-to-noise ratio and pseudo-range residual error of the observation value; and 5: setting system noise according to the overall condition of the observation value and the distribution condition of the participating positioning satellite; step 6: and performing Kalman filtering of GNSS positioning, updating the current state of Kalman filtering, and outputting data. According to the method, the INS is adopted to assist the GNSS positioning to remove the gross errors, and the INS positioning assisted by the GNSS has the characteristics of small positioning error and no influence of sheltered environment in a short time, so that the accuracy of removing the gross errors of the observed values of the GNSS can be effectively improved, and the positioning deviation of the GNSS is reduced.

Description

Coarse error elimination method and system for INS assisted GNSS positioning
Technical Field
The invention relates to the technical field of GNSS/INS navigation, in particular to an INS assisted GNSS positioning gross error elimination method and system.
Background
The GNSS (Global Navigation Satellite System) Navigation and positioning relies on receiving GNSS Satellite signals for positioning, and has the advantages of being all-weather, real-time, high in precision, not accumulating Navigation errors along with time and the like, but also has the problems that signals are easily shielded or interfered, so that positioning cannot be performed, the data updating rate is low, the reliability in a dynamic environment is poor and the like.
An Inertial Navigation System (INS) is an autonomous Navigation System that does not depend on external information. The INS integrates angular velocity and acceleration information of the carrier relative to an inertial space, which are measured by a gyroscope and an accelerometer according to a Newton mechanics principle, to obtain navigation parameters such as three-dimensional velocity, position and attitude information of the carrier. The navigation system has strong autonomy, good concealment, no limit of meteorological conditions and high short-time precision. Its advantages are no influence from external environment (including shielding and electromagnetic interference), high precision in a certain time, and high locating error. The high-precision inertial navigation device can reach millions of RMB, the low-cost inertial navigation device is low in precision and rapid in error diffusion, and long-time independent navigation requirements are difficult to meet.
With the improvement of the requirements on the navigation positioning precision and reliability of the moving carrier, a single navigation system has been difficult to meet the requirements of users. Because the GNSS and the INS have good advantage complementarity, the GNSS/INS combination can improve the overall navigation performance and the navigation accuracy of the system. The GNSS/INS combined navigation can use low-cost inertial navigation devices, has cost advantage and can meet the requirement of civil navigation positioning.
For GNSS positioning, how to eliminate the observation gross error before positioning is a key technical point. The conventional method is to utilize the previous GNSS positioning to obtain the current position by recursion estimation, thereby estimating the residual error of the satellite observation value and then removing the satellite with larger residual error. There are two drawbacks to this approach:
1. there are times when no previous GNSS positioning is available, such as the first positioning after startup, and the first positioning after a severe occluded environment (at which time positioning is not possible).
2. If the previous GNSS positioning is biased significantly, there is a possibility that good observations are rejected.
Disclosure of Invention
The technical problem to be solved by the embodiments of the present invention is to provide a method and a system for removing gross errors in an INS-assisted GNSS positioning, so as to reduce GNSS positioning errors.
In order to solve the above technical problem, an embodiment of the present invention provides a coarse error rejection method for an INS-assisted GNSS positioning, including:
step 1: acquiring GNSS observation data of the current time, wherein the observation comprises one or more of pseudo range, carrier wave and Doppler;
step 2: estimating the state of the GNSS Kalman filter according to the GNSS positioning result at the previous moment, wherein the state comprises a position, a speed, a user receiver clock error and a user receiver clock drift; if the GNSS positioning at the last moment is unavailable, updating the current position and speed of the GNSS Kalman filter by using the position and speed information of the INS, and keeping the clock error and clock drift of the user receiver unchanged;
and step 3: eliminating pseudorange observation value gross errors and eliminating Doppler observation value gross errors;
and 4, step 4: setting the noise of the observed value according to the tracking state, the channel noise, the carrier-to-noise ratio, the pseudo-range residual error and the Doppler residual error of the observed value;
and 5: setting system noise according to the overall condition of the observation value and the distribution condition of the participating positioning satellite;
step 6: and performing Kalman filtering of GNSS positioning, updating the current state of the Kalman filtering, and outputting position, speed, clock error and clock drift data.
Correspondingly, the embodiment of the invention also provides an INS assisted GNSS positioning gross error rejection system, which comprises:
module 1: acquiring GNSS observation data of the current time, wherein the observation comprises one or more of pseudo range, carrier wave and Doppler;
and (3) module 2: estimating the state of the GNSS Kalman filter according to the GNSS positioning result at the previous moment, wherein the state comprises a position, a speed, a user receiver clock error and a user receiver clock drift; if the GNSS positioning at the last moment is unavailable, updating the current position and speed of the GNSS Kalman filter by using the position and speed information of the INS, and keeping the clock error and clock drift of the user receiver unchanged;
and a module 3: eliminating pseudorange observation value gross errors and eliminating Doppler observation value gross errors;
and (4) module: setting the noise of the observed value according to the tracking state, the channel noise, the carrier-to-noise ratio, the pseudo-range residual error and the Doppler residual error of the observed value;
and a module 5: setting system noise according to the overall condition of the observation value and the distribution condition of the participating positioning satellite;
and a module 6: and performing Kalman filtering of GNSS positioning, updating the current state of the Kalman filtering, and outputting position, speed, clock error and clock drift data.
The invention has the beneficial effects that: according to the method, the INS is adopted to assist the GNSS positioning to remove the gross errors, and the INS positioning assisted by the GNSS has the characteristics of small positioning error and no influence of sheltered environment in a short time, so that the accuracy of removing the gross errors of the observed values of the GNSS can be effectively improved, and the positioning deviation of the GNSS is reduced.
Drawings
Fig. 1 is a flowchart illustrating an INS-assisted GNSS positioning gross error rejection method according to an embodiment of the present invention.
Fig. 2 is a general flow diagram of pseudorange calculation according to an embodiment of the invention.
Fig. 3 is a flow chart of pseudorange gross error rejection according to an embodiment of the invention.
Fig. 4 is a flow chart of pseudorange gross error determination and elimination according to an embodiment of the invention.
Figure 5 is a flow chart of rejecting doppler spreads in an embodiment of the present invention.
FIG. 6 is a flow chart of Doppler gross error determination and rejection according to an embodiment of the invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict, and the present invention is further described in detail with reference to the drawings and specific embodiments.
Referring to fig. 1, the method for gross error rejection of INS-assisted GNSS positioning according to the embodiment of the present invention includes steps 1 to 6.
Step 1: GNSS observation data is obtained for a current time, the observations comprising one or more of pseudoranges, carriers, and Doppler observations.
Step 2: estimating the state of a GNSS Kalman filter according to the previous GNSS positioning result, wherein the state comprises a position, a speed, a user receiver clock error and a user receiver clock drift; as an embodiment, the calculation method comprises the following steps:
Figure 373521DEST_PATH_IMAGE001
(formula 1);
wherein the content of the first and second substances,
Figure 671778DEST_PATH_IMAGE002
is the position at the time of k +1,
Figure 996580DEST_PATH_IMAGE003
is the position at the time point k, and,
Figure 38485DEST_PATH_IMAGE004
the velocity at time k + 1;
Figure 538868DEST_PATH_IMAGE005
the velocity at the time of the k-time,
Figure 273606DEST_PATH_IMAGE006
the receiver clock difference is the time k +1,
Figure 554545DEST_PATH_IMAGE007
for the time k the receiver clock difference,
Figure 459529DEST_PATH_IMAGE008
the receiver clock is drifting for time k +1,
Figure 407893DEST_PATH_IMAGE009
for the time k the receiver clock is drifting,
Figure 313532DEST_PATH_IMAGE010
the time difference between time k +1 and time k.
If a previous GNSS location is not available, the current position and velocity of the GNSS Kalman filter are updated with the INS's position and velocity information, and the user receiver clock offset and clock drift remain unchanged.
And step 3: and eliminating the pseudorange observation value gross error and eliminating the Doppler observation value gross error.
And 4, step 4: and measuring noise estimation. And setting the noise of the observed value according to the tracking state, the channel noise, the carrier-to-noise ratio, the pseudo-range residual error and the Doppler residual error of the observed value.
And 5: and estimating system noise. And setting system noise according to the overall condition of the observed value and the distribution condition of the participating positioning satellite.
Step 6: and performing Kalman filtering of GNSS positioning, updating the current state of the Kalman filtering, and outputting data such as position, speed, clock error, clock drift and the like.
In one embodiment, referring to fig. 2, the pseudo-range calculation step is as follows:
and substep 1, calculating local time. The local time is kept by a local clock, and the crystal oscillator frequency offset needs to be corrected during updating.
And a substep 2 of inquiring whether a channel (in which the GNSS chip completes receiving GNSS signals and processing data) completes bit synchronization and frame synchronization or not, and calculating pseudo-range after completion.
Substep 3, reading the channel code phase, the current bit inner code period count and the current frame inner bit count.
And a substep 4 of calculating the satellite signal transmission time according to the code phase, the code period count and the bit count.
Taking GPS L1C/A signal as an example, satellite signal transmission time
Figure 347348DEST_PATH_IMAGE011
The calculation is as follows:
Figure 731055DEST_PATH_IMAGE012
(formula 2)
In the formula 1, the reaction mixture is,
Figure 533926DEST_PATH_IMAGE013
directly reading from a data frame of the satellite at a frame starting moment;
Figure 282571DEST_PATH_IMAGE014
1, counting the bits in the frame, and obtaining the bits after frame synchronization;
Figure 824190DEST_PATH_IMAGE015
counting the code period in 1 bit, and obtaining after bit synchronization;
Figure 11589DEST_PATH_IMAGE016
for the code phase, it can be acquired after stable tracking. The GPS L1C/A code 1 frame contains 300 bits, and 1 bit contains 20 code periods[1]。
Figure 668966DEST_PATH_IMAGE017
Time corresponding to 1 bit, 0.02 s;
Figure 916408DEST_PATH_IMAGE018
the time corresponding to 1 code period is 0.001 s.
And substep 5, calculating the transmission time and the pseudorange.
Pseudo range observed value
Figure 721553DEST_PATH_IMAGE019
The calculation is as follows:
Figure 712642DEST_PATH_IMAGE020
(formula 3)
In formula 3
Figure 490106DEST_PATH_IMAGE021
Is the local time of day or the like,
Figure 908449DEST_PATH_IMAGE022
is the speed of light.
In one embodiment, referring to fig. 3, pseudorange observations are rejected according to the following steps:
1. a pseudorange observation is obtained for the GNSS satellite at the current time, wherein the pseudorange is computed as shown in fig. 2. For satellite i, the pseudorange observations are composed as follows:
Figure 542168DEST_PATH_IMAGE023
(formula 4)
The symbols in the formula have the following meanings:
Figure 664845DEST_PATH_IMAGE019
to be a pseudo-range observation,
Figure 968918DEST_PATH_IMAGE024
is the geometric distance, c is the speed of light,
Figure 558162DEST_PATH_IMAGE025
in order for the receiver to be out of clock,
Figure 541162DEST_PATH_IMAGE026
in order to be the clock error of the satellite,
Figure 874054DEST_PATH_IMAGE027
in order to be an ionospheric delay,
Figure 360530DEST_PATH_IMAGE028
in order to delay the tropospheric delay,
Figure 117746DEST_PATH_IMAGE029
in order to be an error due to the multi-path effect,
Figure 119200DEST_PATH_IMAGE030
for pseudo-range observed value noise, the superscript i is a satellite number;
2. the satellite positions are calculated. The calculation method is described in each GNSS system ICD (Interface Control Document). For example, a Navstar GPS Space Segment/Navigation User interfaces 24 Sep 2013; book beidou satellite navigation system space signal interface control file (version 2.1), 2016 (11) month; european GNSS (Galileo) open Service Signal-in-Space Interface Control Document (1.3). Dec 2016; GLONASS Interface Control Document (Edition 5.1). 2008, etc.
3. The geometric distance between the satellite and the user is calculated. The calculation formula is as follows:
Figure 255784DEST_PATH_IMAGE031
(formula 5)
The symbols in the formula have the following meanings:
Figure 331187DEST_PATH_IMAGE032
which is the geometric distance between the satellite i and the user,
Figure 527813DEST_PATH_IMAGE033
is the three-dimensional coordinates of the user,
Figure 219826DEST_PATH_IMAGE034
is the three-dimensional coordinates of the satellite i,
Figure 894521DEST_PATH_IMAGE035
i is the satellite number for the earth rotation correction of the distance;
user position in the above formula
Figure 355589DEST_PATH_IMAGE033
Distance earth rotation correction given by GNSS/INS combined positioning
Figure 720187DEST_PATH_IMAGE035
The calculation of (a) is completed by using the existing formula. For example, the technical solution disclosed in GPS principle and receiver design, xie-just, electronic industry press 2009 may be adopted.
4. And calculating the clock error of the satellite. The calculation method is shown in each GNSS system ICD.
5. Ionospheric delays are calculated. The calculation method is completed by adopting the existing formula.
6. Tropospheric delay is calculated. The calculation method is completed by adopting the existing formula.
7. And calculating a pseudo-range residual error. The formula is as follows:
Figure 633916DEST_PATH_IMAGE036
(formula 6)
In the formula
Figure 112302DEST_PATH_IMAGE037
The pseudorange residuals for satellite i are known quantities to the right of the equation.
Figure 365560DEST_PATH_IMAGE037
Is the pseudorange residual for satellite i,
Figure 638409DEST_PATH_IMAGE022
in order to be the speed of light,
Figure 39435DEST_PATH_IMAGE025
in order for the receiver to be out of clock,
Figure 321512DEST_PATH_IMAGE038
for multipath effect errors for the satellite i,
Figure 488663DEST_PATH_IMAGE039
to noise the pseudorange observations for satellite i,
Figure 932414DEST_PATH_IMAGE040
to be a pseudorange observation for satellite i,
Figure 86315DEST_PATH_IMAGE041
is the satellite clock offset for the satellite i,
Figure 906503DEST_PATH_IMAGE042
to account for the ionospheric delay for satellite i,
Figure 196670DEST_PATH_IMAGE043
is the tropospheric delay for satellite i.
In the formula, the right side is removed
Figure 873639DEST_PATH_IMAGE040
Besides, the other terms are calculated by formulas, and all the calculation items have errors, including a geometric distance calculation error between the satellite i and a user, a GNSS satellite clock error calculation error, an ionosphere delay correction error and a troposphere delay correction error.
In the formula (6), the first and second polymers,
Figure 249257DEST_PATH_IMAGE041
satellite clock through GNSSCorrecting the difference parameter with a calculation error of less than 3m[5]；
Figure 607557DEST_PATH_IMAGE032
By GNSS/INS fusing positioning errors (i.e.
Figure 14880DEST_PATH_IMAGE033
Error) and satellite position calculation error (i.e., error)
Figure 800434DEST_PATH_IMAGE044
Error), wherein the satellite position calculation error is less than 2 m; ionospheric delay
Figure 663347DEST_PATH_IMAGE042
Calculating by ionosphere parameters and corresponding models, wherein the error of the ionosphere parameters is less than 5 m; tropospheric correction
Figure 825338DEST_PATH_IMAGE043
The error is calculated by a troposphere correction model and is less than 1 m; multipath effect error
Figure 90098DEST_PATH_IMAGE038
It cannot be calculated.
8. And eliminating pseudo range observed values with large residual errors (namely, the pseudo range observed values exceed a preset threshold value, and the threshold value is a large value). As can be seen from the left side of equation 6, the pseudorange residuals of each satellite all contain the same receiver clock difference. Based on the above analysis, the pseudorange correction error sum range can be calculated. What remains unknown is the observation noise and multipath error. The observed value noise and the multipath error of two satellites are small, the pseudo range residual error between the two satellites is close, and the difference between the two satellites is within the range of the sum of the pseudo range correction errors. If the pseudo-range residuals of most satellites are relatively close and the pseudo-range residuals of a few satellites are relatively large in deviation, the observed value noise or the multi-path error of the satellites can be considered to be large, and the observed value noise or the multi-path error can be eliminated.
In one embodiment, referring to fig. 4, the pseudorange gross errors of the satellites are determined and rejected according to the following steps:
1. the pseudorange residuals for all satellites are obtained according to the process shown in fig. 3.
2. All pseudorange residuals are sorted in order from small to large.
3. Selecting the pseudo range residual error of the central position as a reference value and recording the pseudo range residual error as the reference value
Figure 46552DEST_PATH_IMAGE045
。
4. And subtracting the pseudo-range residual errors of other satellites from the reference value, wherein the result is pseudo-range single difference. The pseudorange single difference for the ith satellite is recorded as:
Figure 396762DEST_PATH_IMAGE046
(formula 7)
5. And setting a pseudo range elimination threshold of each satellite according to the signal tracking state of the satellite and the pseudo range single difference, and recording the pseudo range elimination threshold as
Figure 96865DEST_PATH_IMAGE047
If, if
Figure 885305DEST_PATH_IMAGE048
The pseudorange observations are rejected.
As an embodiment, referring to fig. 5, the doppler gross is removed according to the following steps:
1. and acquiring a GNSS satellite Doppler observation value at the current time, wherein the satellite Doppler can be directly acquired from a signal tracking loop of a GNSS baseband. For satellite i, the doppler consists of:
Figure 278240DEST_PATH_IMAGE049
(formula 8)
The symbols in the formula have the following meanings:
Figure 115746DEST_PATH_IMAGE050
: doppler observations of satellite signals;
Figure 619540DEST_PATH_IMAGE051
: a carrier wavelength of the satellite signal;
Figure 593312DEST_PATH_IMAGE052
: the relative velocity of the user and the satellite, i.e., the radial velocity;
Figure 891569DEST_PATH_IMAGE053
；
Figure 216371DEST_PATH_IMAGE054
: a receiver clock drift;
Figure 52085DEST_PATH_IMAGE055
: the clock speed of the satellite;
Figure 145943DEST_PATH_IMAGE056
: doppler observation noise; and (3) labeling: numbering a satellite;
unlike pseudorange observations, ionospheric, tropospheric, and multipath effects have little, if any, effect on doppler observations.
2. A position vector between the user to the satellite is calculated.
Assume the user position is
Figure 615101DEST_PATH_IMAGE033
The location of the ith satellite is
Figure 161620DEST_PATH_IMAGE034
Calculating the distance from the user to the ith satellite according to equation 5
Figure 272796DEST_PATH_IMAGE032
. User to ith satellite position vector
Figure 893264DEST_PATH_IMAGE057
The calculation is as follows:
Figure 798903DEST_PATH_IMAGE058
(formula 9)
3. The satellite velocity and the user velocity are obtained.
Suppose the velocity of satellite i
Figure 665726DEST_PATH_IMAGE059
Speed of user
Figure 783855DEST_PATH_IMAGE060
. The satellite velocity is obtained simultaneously when calculating the satellite position, the user velocity being provided by the GNSS/INS combined positioning.
4. The projected component of the user and satellite relative velocities on the position vector is calculated.
First, the relative velocity between the receiver and the ith satellite is calculated
Figure 852305DEST_PATH_IMAGE061
The formula is as follows:
Figure 928845DEST_PATH_IMAGE062
(formula 10)
Projection component of velocity vector on position vector
Figure 449956DEST_PATH_IMAGE063
The calculation is as follows:
Figure 637355DEST_PATH_IMAGE064
(formula 11)
5. Calculating the radial velocity of the user and the satellite i
Figure 560312DEST_PATH_IMAGE065
The formula is as follows:
Figure 807754DEST_PATH_IMAGE066
(formula 12)
In the formula
Figure 609969DEST_PATH_IMAGE067
For correcting the earth rotation of the speed, the calculation is completed by adopting the existing formula[5]。
6. And calculating the clock speed of the satellite. The calculation method is shown in each GNSS system ICD[1][2][3][4]。
7. The doppler residual is calculated. The formula is as follows:
Figure 601059DEST_PATH_IMAGE068
(formula 13)
In the formula
Figure 581784DEST_PATH_IMAGE069
The doppler residuals for satellite i are known quantities to the right of the formula.
Figure 796865DEST_PATH_IMAGE022
In order to be the speed of light,
Figure 230251DEST_PATH_IMAGE054
in order for the receiver to drift in the clock,
Figure 821770DEST_PATH_IMAGE070
is the doppler observation noise for satellite i,
Figure 453739DEST_PATH_IMAGE071
is the doppler observation of the satellite i signal,
Figure 246246DEST_PATH_IMAGE072
is the carrier wavelength of the satellite i signal,
Figure 23053DEST_PATH_IMAGE065
for users and satellites
Figure 355946DEST_PATH_IMAGE073
The radial velocity of the magnetic field generating device,
Figure 842422DEST_PATH_IMAGE074
as a satellite
Figure 868147DEST_PATH_IMAGE073
Clock speed.
Similar to the pseudorange residuals, the pseudorange residuals are,
Figure 276125DEST_PATH_IMAGE065
the error is determined by the user velocity error and the satellite velocity error. Wherein the satellite velocity error is less than 0.001m/s[6](ii) a The combined GNSS/INS positioning provides a velocity error of less than 0.1 m/s. The calculation error of the satellite clock speed is negligible.
8. And eliminating Doppler observed values with large residual errors (namely exceeding a preset threshold value). As can be seen from the left side of equation 13, the doppler residuals of each satellite all contain the same receiver clock drift. Based on the above analysis, the range of the doppler correction error sum can be calculated. What remains unknown is the observation noise. If the observed values of two satellites are less noisy, the doppler residuals between the two satellites are closer, and the difference between the two is within the range of the doppler correction error sum. If the Doppler residuals of most satellites are relatively close and the Doppler residual error of a small number of satellites is relatively large, the Doppler observed values of the satellites are considered to be relatively noisy, and the Doppler observed values can be eliminated.
In one embodiment, referring to fig. 6, the doppler gross error determination and rejection for the satellite are performed according to the following steps:
1. according to the process shown in fig. 5, the doppler residuals of all satellites are obtained.
2. All doppler residuals are sorted in order from small to large.
3. Selecting the Doppler residual error of the center position as a reference value, and recording the Doppler residual error as the reference value
Figure 943867DEST_PATH_IMAGE075
。
4. And (4) subtracting the Doppler residual errors of other satellites from the reference value to obtain a Doppler single difference. The Doppler single difference for the ith satellite is noted as:
Figure 550429DEST_PATH_IMAGE076
(formula 14)
5. Setting the Doppler elimination threshold of each satellite according to the signal tracking state and the Doppler single difference of the satellites, and recording the Doppler elimination threshold as
Figure 950318DEST_PATH_IMAGE077
If, if
Figure 170559DEST_PATH_IMAGE078
The Doppler observations are rejected.
The gross error rejection system for INS assisted GNSS positioning in the embodiment of the invention comprises:
module 1: acquiring GNSS observation data of the current time, wherein the observation comprises one or more of pseudo range, carrier wave and Doppler;
and (3) module 2: estimating the state of a GNSS Kalman filter according to the previous GNSS positioning result, wherein the state comprises a position, a speed, a user receiver clock error and a user receiver clock drift; if the previous GNSS positioning is unavailable, updating the current position and speed of the GNSS Kalman filter by using the position and speed information of the INS, and keeping the clock error and the clock drift of the user receiver unchanged;
and a module 3: eliminating pseudorange observation value gross errors and eliminating Doppler observation value gross errors;
and (4) module: setting the noise of the observed value according to the tracking state, the channel noise, the carrier-to-noise ratio, the pseudo-range residual error and the Doppler residual error of the observed value;
and a module 5: setting system noise according to the overall condition of the observation value and the distribution condition of the participating positioning satellite;
and a module 6: and performing Kalman filtering of GNSS positioning, updating the current state of the Kalman filtering, and outputting position, speed, clock error and clock drift data.
As an embodiment, the module 1 comprises the following sub-modules:
submodule 1, calculating local time;
the submodule 2 inquires whether the channel completes bit synchronization and frame synchronization, and the submodule 3 is accessed after the completion of the bit synchronization and the frame synchronization;
a submodule 3 for reading the channel code phase, the current bit internal code period count and the current frame internal bit count;
the submodule 4 calculates the satellite signal transmitting time according to the code phase, the code period count and the bit count;
the submodule 5 calculates the emission time and the pseudo-range observed value; wherein pseudorange observations
Figure 314095DEST_PATH_IMAGE019
The calculation is as follows:
Figure 775164DEST_PATH_IMAGE020
；
wherein the content of the first and second substances,
Figure 673849DEST_PATH_IMAGE021
is the local time of day or the like,
Figure 853158DEST_PATH_IMAGE022
in order to be the speed of light,
Figure 65965DEST_PATH_IMAGE011
is the satellite signal transmission time.
As an embodiment, in the module 2, the state of the GNSS kalman filter is calculated by using the following formula:
Figure 381540DEST_PATH_IMAGE001
；
wherein the content of the first and second substances,
Figure 919968DEST_PATH_IMAGE002
is the position at the time of k +1,
Figure 318064DEST_PATH_IMAGE003
is the position at the time point k, and,
Figure 600141DEST_PATH_IMAGE004
the velocity at time k + 1;
Figure 35801DEST_PATH_IMAGE005
the velocity at the time of the k-time,
Figure 479552DEST_PATH_IMAGE006
the receiver clock difference is the time k +1,
Figure 633453DEST_PATH_IMAGE007
for the time k the receiver clock difference,
Figure 125745DEST_PATH_IMAGE008
the receiver clock is drifting for time k +1,
Figure 150333DEST_PATH_IMAGE009
for the time k the receiver clock is drifting,
Figure 558793DEST_PATH_IMAGE010
the time difference between time k +1 and time k.
In block 3, as an embodiment, pseudorange observation gross errors are rejected according to the following steps:
acquiring a pseudo-range observed value of a GNSS satellite at the current time;
calculating the satellite position;
and calculating the geometric distance between the satellite and the user according to the following calculation formula:
Figure 934411DEST_PATH_IMAGE031
；
wherein the content of the first and second substances,
Figure 292711DEST_PATH_IMAGE032
which is the geometric distance between the satellite i and the user,
Figure 109488DEST_PATH_IMAGE033
is the three-dimensional coordinates of the user,
Figure 160621DEST_PATH_IMAGE034
is the three-dimensional coordinates of the satellite i,
Figure 757956DEST_PATH_IMAGE035
i is the satellite number for the earth rotation correction of the distance;
calculating the clock error of the satellite;
calculating ionospheric delay;
calculating tropospheric delay;
calculating a pseudo-range residual error according to the following calculation formula:
Figure 919947DEST_PATH_IMAGE036
；
Figure 181776DEST_PATH_IMAGE037
is the pseudorange residual for satellite i,
Figure 200548DEST_PATH_IMAGE022
in order to be the speed of light,
Figure 285178DEST_PATH_IMAGE025
in order for the receiver to be out of clock,
Figure 250860DEST_PATH_IMAGE038
for multipath effect errors for the satellite i,
Figure 370126DEST_PATH_IMAGE039
to noise the pseudorange observations for satellite i,
Figure 497482DEST_PATH_IMAGE040
to be a pseudorange observation for satellite i,
Figure 334988DEST_PATH_IMAGE041
is the satellite clock offset for the satellite i,
Figure 838782DEST_PATH_IMAGE042
to account for the ionospheric delay for satellite i,
Figure 481728DEST_PATH_IMAGE043
is the tropospheric delay for satellite i;
and eliminating pseudo-range observed values of which residual errors exceed a preset threshold value.
In one embodiment, in the module 3, the pseudorange gross errors of the satellites are determined and rejected according to the following steps:
obtaining pseudo-range residuals of all satellites;
sequencing all pseudo-range residuals from small to large;
selecting the pseudo range residual error of the central position as a reference value and recording the pseudo range residual error as the reference value
Figure 45565DEST_PATH_IMAGE045
；
And subtracting the pseudo-range residual errors of other satellites from the reference value to obtain a result, namely pseudo-range single difference, and recording the pseudo-range single difference of the ith satellite as:
Figure 104788DEST_PATH_IMAGE046
；
and setting a pseudo range elimination threshold of each satellite according to the signal tracking state of the satellite and the pseudo range single difference, and recording the pseudo range elimination threshold as
Figure 412272DEST_PATH_IMAGE047
If, if
Figure 506130DEST_PATH_IMAGE048
The pseudorange observations are rejected.
In block 3, as an embodiment, the doppler gross is removed according to the following steps:
acquiring a GNSS satellite Doppler observation value at the current time;
calculating a position vector between the user and the satellite;
acquiring satellite speed and user speed;
calculating a projection component of the relative speed of the user and the satellite on a position vector;
calculating the radial speed of the user and the satellite i;
calculating the clock speed of the satellite;
the doppler residual is calculated according to the following formula:
Figure 240868DEST_PATH_IMAGE068
；
in the formula
Figure 787387DEST_PATH_IMAGE069
Is the doppler residual for the satellite i,
Figure 653491DEST_PATH_IMAGE022
in order to be the speed of light,
Figure 336276DEST_PATH_IMAGE054
in order for the receiver to drift in the clock,
Figure 241915DEST_PATH_IMAGE070
is the doppler observation noise for satellite i,
Figure 275730DEST_PATH_IMAGE079
is the doppler observation of the satellite i signal,
Figure 190597DEST_PATH_IMAGE080
is the carrier wavelength of the satellite i signal,
Figure 259047DEST_PATH_IMAGE065
for users and satellites
Figure 70008DEST_PATH_IMAGE073
The radial velocity of the magnetic field generating device,
Figure 591119DEST_PATH_IMAGE074
as a satellite
Figure 41168DEST_PATH_IMAGE073
Clock speed;
and eliminating Doppler observed values with residual errors exceeding a preset threshold value.
In one embodiment, in block 3, the doppler spread determination and rejection for the satellite are performed according to the following steps:
acquiring Doppler residuals of all satellites;
sequencing all Doppler residuals from small to large;
selecting the Doppler residual error of the center position as a reference value, and recording the Doppler residual error as the reference value
Figure 964124DEST_PATH_IMAGE075
；
And (3) subtracting the Doppler residual errors of other satellites from the reference value to obtain a result, namely the Doppler single difference, and recording the Doppler single difference of the ith satellite as:
Figure 211566DEST_PATH_IMAGE076
；
setting the Doppler elimination threshold of each satellite according to the signal tracking state and the Doppler single difference of the satellites, and recording the Doppler elimination threshold as
Figure 954394DEST_PATH_IMAGE077
If, if
Figure 945484DEST_PATH_IMAGE078
The Doppler observations are rejected.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (12)

1. A gross error rejection method for INS assisted GNSS positioning is characterized by comprising the following steps:
step 1: acquiring GNSS observation data of the current time, wherein the observation comprises one or more of pseudo range, carrier wave and Doppler;
step 2: estimating the state of the GNSS Kalman filter according to the GNSS positioning result at the previous moment, wherein the state comprises a position, a speed, a user receiver clock error and a user receiver clock drift; if the GNSS positioning at the last moment is unavailable, updating the current position and speed of the GNSS Kalman filter by using the position and speed information of the INS, and keeping the clock error and clock drift of the user receiver unchanged;
and step 3: eliminating pseudorange observation value gross errors and eliminating Doppler observation value gross errors;
and 4, step 4: setting the noise of the observed value according to the tracking state, the channel noise, the carrier-to-noise ratio, the pseudo-range residual error and the Doppler residual error of the observed value;
and 5: setting system noise according to the overall condition of the observation value and the distribution condition of the participating positioning satellite;
step 6: performing Kalman filtering of GNSS positioning, updating the current state of the Kalman filtering, and outputting position, speed, clock error and clock drift data;
in step 2, the state of the GNSS kalman filter is calculated using the following formula:
Figure 912482DEST_PATH_IMAGE001
；
wherein the content of the first and second substances,
Figure 848077DEST_PATH_IMAGE002
is the position at the time of k +1,
Figure 789095DEST_PATH_IMAGE003
is the position at the time point k, and,
Figure 632286DEST_PATH_IMAGE004
the velocity at time k + 1;
Figure 211034DEST_PATH_IMAGE005
the velocity at the time of the k-time,
Figure 818996DEST_PATH_IMAGE006
the receiver clock difference is the time k +1,
Figure 483195DEST_PATH_IMAGE007
for the time k the receiver clock difference,
Figure 130077DEST_PATH_IMAGE008
the receiver clock is drifting for time k +1,
Figure 61868DEST_PATH_IMAGE009
for the time k the receiver clock is drifting,
Figure 667161DEST_PATH_IMAGE010
the time difference between time k +1 and time k.
2. The method for gross error rejection in INS-assisted GNSS positioning as claimed in claim 1, wherein in step 1, the pseudorange observations are computed according to the following steps:
substep 1, calculating local time;
substep 2, inquiring whether the channel completes bit synchronization and frame synchronization, and entering substep 3 after completion;
substep 3, reading channel code phase, current bit internal code period count and current frame internal bit count;
substep 4, calculating the satellite signal transmitting time according to the code phase, the code period count and the bit count;
substep 5, calculating emission time and pseudo-range observed values; wherein pseudorange observations
Figure 851280DEST_PATH_IMAGE011
The calculation is as follows:
Figure 301853DEST_PATH_IMAGE012
；
wherein the content of the first and second substances,
Figure 353729DEST_PATH_IMAGE013
is the local time of day or the like,
Figure 395504DEST_PATH_IMAGE014
in order to be the speed of light,
Figure 768716DEST_PATH_IMAGE015
is the satellite signal transmission time.
3. The method as claimed in claim 2, wherein in step 3, pseudorange observation gross errors are removed according to the following steps:
acquiring a pseudo-range observed value of a GNSS satellite at the current time;
calculating the satellite position;
and calculating the geometric distance between the satellite and the user according to the following calculation formula:
Figure 524445DEST_PATH_IMAGE016
；
wherein the content of the first and second substances,
Figure 666713DEST_PATH_IMAGE017
which is the geometric distance between the satellite i and the user,
Figure 581186DEST_PATH_IMAGE018
is the three-dimensional coordinates of the user,
Figure 441695DEST_PATH_IMAGE019
is the three-dimensional coordinates of the satellite i,
Figure 797852DEST_PATH_IMAGE020
i is the satellite number for the earth rotation correction of the distance;
calculating the clock error of the satellite;
calculating ionospheric delay;
calculating tropospheric delay;
calculating a pseudo-range residual error according to the following calculation formula:
Figure 60206DEST_PATH_IMAGE021
；
Figure 381466DEST_PATH_IMAGE022
is the pseudorange residual for satellite i,
Figure 198112DEST_PATH_IMAGE014
in order to be the speed of light,
Figure 230397DEST_PATH_IMAGE023
in order for the receiver to be out of clock,
Figure 816099DEST_PATH_IMAGE024
for multipath effect errors for the satellite i,
Figure 104998DEST_PATH_IMAGE025
to noise the pseudorange observations for satellite i,
Figure 644826DEST_PATH_IMAGE026
to be a pseudorange observation for satellite i,
Figure 247846DEST_PATH_IMAGE027
is the satellite clock offset for the satellite i,
Figure 953633DEST_PATH_IMAGE028
to account for the ionospheric delay for satellite i,
Figure 351117DEST_PATH_IMAGE029
is the tropospheric delay for satellite i;
and eliminating pseudo-range observed values of which residual errors exceed a preset threshold value.
4. The method as claimed in claim 3, wherein in step 3, the pseudorange gross errors of the satellites are determined and removed according to the following steps:
obtaining pseudo-range residuals of all satellites;
sequencing all pseudo-range residuals from small to large;
selecting the pseudo range residual error of the central position as a reference value and recording the pseudo range residual error as the reference value
Figure 476828DEST_PATH_IMAGE030
；
And subtracting the pseudo-range residual errors of other satellites from the reference value to obtain a result, namely pseudo-range single difference, and recording the pseudo-range single difference of the ith satellite as:
Figure 617959DEST_PATH_IMAGE031
；
and setting a pseudo range elimination threshold of each satellite according to the signal tracking state of the satellite and the pseudo range single difference, and recording the pseudo range elimination threshold as
Figure 912674DEST_PATH_IMAGE032
If, if
Figure 481059DEST_PATH_IMAGE033
The pseudorange observations are rejected.
5. The method as claimed in claim 1, wherein in step 3, the doppler spread is removed according to the following steps:
acquiring a GNSS satellite Doppler observation value at the current time;
calculating a position vector between the user and the satellite;
acquiring satellite speed and user speed;
calculating a projection component of the relative speed of the user and the satellite on a position vector;
calculating the radial speed of the user and the satellite i;
calculating the clock speed of the satellite;
the doppler residual is calculated according to the following formula:
Figure 261058DEST_PATH_IMAGE034
；
in the formula
Figure 205881DEST_PATH_IMAGE035
Is the doppler residual for the satellite i,
Figure 620681DEST_PATH_IMAGE014
in order to be the speed of light,
Figure 625547DEST_PATH_IMAGE036
in order for the receiver to drift in the clock,
Figure 421071DEST_PATH_IMAGE037
is the doppler observation noise for satellite i,
Figure 107267DEST_PATH_IMAGE038
is the doppler observation of the satellite i signal,
Figure 642154DEST_PATH_IMAGE039
is the carrier wavelength of the satellite i signal,
Figure 552341DEST_PATH_IMAGE040
for users and satellites
Figure 41353DEST_PATH_IMAGE041
The radial velocity of the magnetic field generating device,
Figure 593557DEST_PATH_IMAGE042
as a satellite
Figure 982950DEST_PATH_IMAGE041
Clock speed;
and eliminating Doppler observed values with residual errors exceeding a preset threshold value.
6. The method as claimed in claim 5, wherein in step 3, the Doppler gross error determination and elimination are performed on the satellites according to the following steps:
acquiring Doppler residuals of all satellites;
sequencing all Doppler residuals from small to large;
selecting the Doppler residual error of the center position as a reference value, and recording the Doppler residual error as the reference value
Figure 329618DEST_PATH_IMAGE043
；
And (3) subtracting the Doppler residual errors of other satellites from the reference value to obtain a result, namely the Doppler single difference, and recording the Doppler single difference of the ith satellite as:
Figure 302997DEST_PATH_IMAGE044
；
setting the Doppler elimination threshold of each satellite according to the signal tracking state and the Doppler single difference of the satellites, and recording the Doppler elimination threshold as
Figure 127733DEST_PATH_IMAGE045
If, if
Figure 371633DEST_PATH_IMAGE046
The Doppler observations are rejected.
7. An INS-assisted GNSS-positioned gross error rejection system, comprising:
module 1: acquiring GNSS observation data of the current time, wherein the observation comprises one or more of pseudo range, carrier wave and Doppler;
and (3) module 2: estimating the state of the GNSS Kalman filter according to the GNSS positioning result at the previous moment, wherein the state comprises a position, a speed, a user receiver clock error and a user receiver clock drift; if the GNSS positioning at the last moment is unavailable, updating the current position and speed of the GNSS Kalman filter by using the position and speed information of the INS, and keeping the clock error and clock drift of the user receiver unchanged;
and a module 3: eliminating pseudorange observation value gross errors and eliminating Doppler observation value gross errors;
and (4) module: setting the noise of the observed value according to the tracking state, the channel noise, the carrier-to-noise ratio, the pseudo-range residual error and the Doppler residual error of the observed value;
and a module 5: setting system noise according to the overall condition of the observation value and the distribution condition of the participating positioning satellite;
and a module 6: performing Kalman filtering of GNSS positioning, updating the current state of the Kalman filtering, and outputting position, speed, clock error and clock drift data;
in block 2, the state of the GNSS kalman filter is calculated using the following formula:
Figure 889202DEST_PATH_IMAGE001
；
wherein the content of the first and second substances,
Figure 54604DEST_PATH_IMAGE002
is the position at the time of k +1,
Figure 184496DEST_PATH_IMAGE003
is the position at the time point k, and,
Figure 282902DEST_PATH_IMAGE004
the velocity at time k + 1;
Figure 971373DEST_PATH_IMAGE005
the velocity at the time of the k-time,
Figure 420809DEST_PATH_IMAGE006
the receiver clock difference is the time k +1,
Figure 85883DEST_PATH_IMAGE007
for the time k the receiver clock difference,
Figure 101112DEST_PATH_IMAGE008
the receiver clock is drifting for time k +1,
Figure 960484DEST_PATH_IMAGE009
for the time k the receiver clock is drifting,
Figure 133102DEST_PATH_IMAGE010
the time difference between time k +1 and time k.
8. The INS-assisted GNSS positioning gross rejection system according to claim 7, wherein module 1 comprises the following sub-modules:
submodule 1, calculating local time;
the submodule 2 inquires whether the channel completes bit synchronization and frame synchronization, and the submodule 3 is accessed after the completion of the bit synchronization and the frame synchronization;
a submodule 3 for reading the channel code phase, the current bit internal code period count and the current frame internal bit count;
the submodule 4 calculates the satellite signal transmitting time according to the code phase, the code period count and the bit count;
the submodule 5 calculates the emission time and the pseudo-range observed value; wherein pseudorange observations
Figure 368911DEST_PATH_IMAGE011
The calculation is as follows:
Figure 441909DEST_PATH_IMAGE012
；
wherein the content of the first and second substances,
Figure 472182DEST_PATH_IMAGE013
is the local time of day or the like,
Figure 129166DEST_PATH_IMAGE014
in order to be the speed of light,
Figure 637508DEST_PATH_IMAGE015
is the satellite signal transmission time.
9. The INS-assisted GNSS positioning gross error rejection system according to claim 8, wherein in block 3, pseudorange observations gross error is rejected according to the following steps:
acquiring a pseudo-range observed value of a GNSS satellite at the current time;
calculating the satellite position;
and calculating the geometric distance between the satellite and the user according to the following calculation formula:
Figure 830592DEST_PATH_IMAGE016
；
wherein the content of the first and second substances,
Figure 766187DEST_PATH_IMAGE017
which is the geometric distance between the satellite i and the user,
Figure 710134DEST_PATH_IMAGE018
is the three-dimensional coordinates of the user,
Figure 22167DEST_PATH_IMAGE019
is the three-dimensional coordinates of the satellite i,
Figure 69757DEST_PATH_IMAGE020
i is the satellite number for the earth rotation correction of the distance;
calculating the clock error of the satellite;
calculating ionospheric delay;
calculating tropospheric delay;
calculating a pseudo-range residual error according to the following calculation formula:
Figure 441833DEST_PATH_IMAGE021
；
Figure 73409DEST_PATH_IMAGE022
is the pseudorange residual for satellite i,
Figure 923553DEST_PATH_IMAGE014
in order to be the speed of light,
Figure 91229DEST_PATH_IMAGE023
in order for the receiver to be out of clock,
Figure 634206DEST_PATH_IMAGE024
for multipath effect errors for the satellite i,
Figure 490429DEST_PATH_IMAGE025
to noise the pseudorange observations for satellite i,
Figure 409843DEST_PATH_IMAGE026
to be a pseudorange observation for satellite i,
Figure 166447DEST_PATH_IMAGE027
is the satellite clock offset for the satellite i,
Figure 880325DEST_PATH_IMAGE028
to account for the ionospheric delay for satellite i,
Figure 486493DEST_PATH_IMAGE029
is the tropospheric delay for satellite i;
and eliminating pseudo-range observed values of which residual errors exceed a preset threshold value.
10. The system for coarse rejection in an INS-assisted GNSS positioning of claim 9 wherein in block 3, the pseudorange gross of a satellite is determined and rejected according to the following steps:
obtaining pseudo-range residuals of all satellites;
sequencing all pseudo-range residuals from small to large;
selecting the pseudo range residual error of the central position as a reference value and recording the pseudo range residual error as the reference value
Figure 147282DEST_PATH_IMAGE030
；
And subtracting the pseudo-range residual errors of other satellites from the reference value to obtain a result, namely pseudo-range single difference, and recording the pseudo-range single difference of the ith satellite as:
Figure 758392DEST_PATH_IMAGE031
；
and setting a pseudo range elimination threshold of each satellite according to the signal tracking state of the satellite and the pseudo range single difference, and recording the pseudo range elimination threshold as
Figure 908750DEST_PATH_IMAGE032
If, if
Figure 739565DEST_PATH_IMAGE033
The pseudorange observations are rejected.
11. The INS-assisted GNSS positioning gross error rejection system according to claim 7, wherein in module 3, doppler gross errors are rejected according to the following steps:
acquiring a GNSS satellite Doppler observation value at the current time;
calculating a position vector between the user and the satellite;
acquiring satellite speed and user speed;
calculating a projection component of the relative speed of the user and the satellite on a position vector;
calculating the radial speed of the user and the satellite i;
calculating the clock speed of the satellite;
the doppler residual is calculated according to the following formula:
Figure 735203DEST_PATH_IMAGE034
；
in the formula
Figure 466399DEST_PATH_IMAGE035
Is the doppler residual for the satellite i,
Figure 53238DEST_PATH_IMAGE014
in order to be the speed of light,
Figure 102840DEST_PATH_IMAGE036
in order for the receiver to drift in the clock,
Figure 167748DEST_PATH_IMAGE037
is the doppler observation noise for satellite i,
Figure 753450DEST_PATH_IMAGE038
is the doppler observation of the satellite i signal,
Figure 980032DEST_PATH_IMAGE039
is the carrier wavelength of the satellite i signal,
Figure 785440DEST_PATH_IMAGE040
for users and satellites
Figure 388459DEST_PATH_IMAGE041
The radial velocity of the magnetic field generating device,
Figure 828668DEST_PATH_IMAGE042
as a satellite
Figure 491730DEST_PATH_IMAGE041
Clock speed;
and eliminating Doppler observed values with residual errors exceeding a preset threshold value.
12. The system for gross error rejection in an INS-assisted GNSS positioning of claim 11 wherein in block 3, the doppler gross error determination and rejection for satellites is performed according to the following steps:
acquiring Doppler residuals of all satellites;
sequencing all Doppler residuals from small to large;
selecting the Doppler residual error of the center position as a reference value, and recording the Doppler residual error as the reference value
Figure 539362DEST_PATH_IMAGE043
；
And (3) subtracting the Doppler residual errors of other satellites from the reference value to obtain a result, namely the Doppler single difference, and recording the Doppler single difference of the ith satellite as:
Figure 680494DEST_PATH_IMAGE044
；
setting the Doppler elimination threshold of each satellite according to the signal tracking state and the Doppler single difference of the satellites, and recording the Doppler elimination threshold as
Figure 37526DEST_PATH_IMAGE045
If, if
Figure 605910DEST_PATH_IMAGE046
The Doppler observations are rejected.
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