CN112902950A - Novel initial alignment method for MEMS-level IMU in low-speed motion carrier - Google Patents

Novel initial alignment method for MEMS-level IMU in low-speed motion carrier Download PDF

Info

Publication number
CN112902950A
CN112902950A CN202110080286.9A CN202110080286A CN112902950A CN 112902950 A CN112902950 A CN 112902950A CN 202110080286 A CN202110080286 A CN 202110080286A CN 112902950 A CN112902950 A CN 112902950A
Authority
CN
China
Prior art keywords
carrier
initial alignment
vector
time
increment
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202110080286.9A
Other languages
Chinese (zh)
Other versions
CN112902950B (en
Inventor
罗亚荣
游盛勇
胡建朗
郭迟
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wuhan University WHU
Original Assignee
Wuhan University WHU
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wuhan University WHU filed Critical Wuhan University WHU
Priority to CN202110080286.9A priority Critical patent/CN112902950B/en
Publication of CN112902950A publication Critical patent/CN112902950A/en
Application granted granted Critical
Publication of CN112902950B publication Critical patent/CN112902950B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C25/00—Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
    • G01C25/005—Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass initial alignment, calibration or starting-up of inertial devices

Abstract

The invention provides a novel initial alignment method for an MEMS-level IMU in a low-speed moving carrier. The navigation system acquires the latitude and longitude of the carrier at the initialization moment and the latitude and longitude of the carrier at different moments and transmits the latitude and longitude to the microprocessor; the IMU module collects angular velocity increment information and velocity increment information of adjacent moments and transmits the angular velocity increment information and the velocity increment information to the microprocessor; the microprocessor selects a proper initial alignment ending time, and calculates a real position increment vector of the carrier from the initial alignment starting time to the initial alignment ending time; obtaining latitude and longitude estimated values of the carrier at the initial alignment end moment by using angle and speed increment information at adjacent moments through a mechanical arrangement algorithm, and then calculating position increment vector estimated values of the carrier from the initial alignment start moment to the initial alignment end moment; calculating to obtain a course error angle; and the microprocessor feeds back the obtained course error angle to the strapdown inertial navigation system to realize the initial alignment of the navigation system. The invention improves the initial alignment precision of the inertial navigation system.

Description

Novel initial alignment method for MEMS-level IMU in low-speed motion carrier
Technical Field
The invention belongs to the technical field of navigation methods and application, and particularly relates to a novel initial alignment method for an MEMS-level IMU in a low-speed motion carrier.
Background
Due to the excellent autonomy of the inertial navigation system, the inertial navigation system is widely applied to low-speed motion carriers such as patrol robots and the like. The strapdown inertial navigation system firstly performs initial alignment before starting a navigation task, and aims to establish an accurate initial attitude matrix so as to obtain the attitude of a carrier relative to a space. The alignment accuracy and time are important indexes of initial alignment and reflect the navigation performance of the system. As a key technology of the inertial navigation system, initial alignment is always a research hotspot of the autonomous navigation system.
The initial attitude matrix contains roll angle, pitch angle, and heading angle. For low cost MEMS-level IMUs, pitch and roll angles can be obtained by means of static base gravimetry, and therefore estimation of initial heading error is a major task of the dynamic coarse alignment method.
The traditional method is to estimate the initial course error by establishing an error dynamic model of a nonlinear inertial navigation system and utilizing Kalman filtering. However, the methods are all oriented to high-speed moving carriers, and for low-speed moving carriers configured with low-grade IMUs and single-antenna GNSS measurement systems, the methods are high in computation amount and long in computation time.
Aiming at the existing problems, the invention provides a novel initial alignment method for a low-cost MEMS-level IMU in a low-speed motion carrier. Compared with the traditional method, the method has the advantages of short alignment time and simple calculation while ensuring the alignment precision, and has good application prospect in practical engineering.
The strapdown inertial navigation system moving in a small range on the earth surface has one characteristic: a pure rotation relation exists between the carrier motion track obtained through calculation of the strap-down inertial navigation system with the initial alignment error and the real motion track of the carrier, and the pure rotation error is mainly caused by the initial alignment error. Based on the characteristic of a strapdown inertial navigation system, the method solves the initial alignment error in a reverse mode, and therefore the initial alignment of the low-speed motion carrier is achieved.
Disclosure of Invention
The invention provides a novel initial alignment method for an MEMS-level IMU in a low-speed moving carrier.
The positioning system of the present invention comprises: the system comprises a microprocessor, a navigation system and an IMU module;
and the microprocessor is respectively connected with the navigation system and the IMU module in sequence.
The initial alignment method facing the low-speed moving carrier comprises the following steps:
step 1: the navigation system acquires the latitude of the carrier at the initialization moment and the longitude of the carrier at the initialization moment, acquires the latitude of the carrier at different moments and the longitude of the carrier at different moments, and transmits the latitude of the carrier at the initialization moment, the longitude of the carrier at the initialization moment, the latitude of the carrier at different moments and the longitude of the carrier at different moments to the microprocessor; the IMU module acquires angular velocity increment information of adjacent moments and speed increment information of the adjacent moments, and transmits the angular velocity increment information of the adjacent moments and the speed increment information of the adjacent moments to the microprocessor;
step 2: the microprocessor selects a proper acquisition time as an initial alignment end time, and calculates a real position increment vector of the carrier from the initial alignment start time to the initial alignment end time;
and step 3: the microprocessor obtains the latitude estimated value of the carrier at the initial alignment ending time and the longitude estimated value of the carrier at the initial alignment ending time by using the angle increment information and the speed increment information of adjacent moments through a mechanical arrangement algorithm of a strapdown inertial navigation system, and calculates the position increment vector estimated value of the carrier from the initial alignment starting time to the initial alignment ending time;
and 4, step 4: calculating to obtain a course error angle through a real position increment vector of the carrier from the initial alignment starting moment to the initial alignment ending moment and a position increment vector estimated value of the carrier from the initial alignment starting moment to the initial alignment ending moment;
and 5: and (4) the microprocessor feeds back the course error angle obtained in the step (4) to the strapdown inertial navigation system to correct the initial navigation attitude, so that the initial alignment of the navigation system is realized.
Preferably, the latitude of the carrier at the initial alignment time in step 1 is:
Figure BDA0002908979600000021
wherein the content of the first and second substances,
Figure BDA0002908979600000022
denotes the vector at t0The latitude of the moment;
the longitude of the initial alignment time carrier in the step 1 is as follows:
Figure BDA0002908979600000023
wherein the content of the first and second substances,
Figure BDA0002908979600000024
denotes the vector at t0The longitude of the time of day;
step 1, the latitude of the carrier at different moments is as follows:
Figure BDA0002908979600000025
i∈[1，N]
wherein the content of the first and second substances,
Figure BDA0002908979600000026
denotes the vector at tiLatitude of the moment, N represents the number of the acquisition moments;
the longitude of the carrier at different moments in the step 1 is as follows:
Figure BDA0002908979600000027
i∈[1，N]
wherein the content of the first and second substances,
Figure BDA0002908979600000031
presentation carrierAt tiLongitude of the time, N representing the number of acquisition times;
step 1, the angular velocity increment information of the adjacent time is as follows:
Figure BDA0002908979600000032
wherein the content of the first and second substances,
Figure BDA0002908979600000033
denotes the vector from ti-1To tiAngular velocity increment information of the time;
step 1, the speed increment information of the adjacent time is as follows:
Figure BDA0002908979600000034
wherein the content of the first and second substances,
Figure BDA0002908979600000035
denotes the vector from ti-1To tiVelocity increment information of the time;
preferably, t is calculated as described in step 20To tkThe true position increment vector for the carrier is:
Figure BDA0002908979600000036
wherein, t0Indicates the initial alignment start time, tkIndicating an initial alignment end time;
Figure BDA0002908979600000037
the vector coordinate system b representing the acquisition of the navigation system is from t0To tkThe vector of true position increments of the carrier in the navigation coordinate system n,
Figure BDA0002908979600000038
the vector coordinate system b collected for the navigation system is at t0The representation of the true position vector in the navigation coordinate system n,
Figure BDA0002908979600000039
the vector coordinate system b collected for the navigation system is at tkIn the navigation coordinate system n.
Preferably, in step 3, the calculating of the estimated value of the position increment vector of the carrier from the initial alignment starting time to the initial alignment ending time is as follows:
Figure BDA00029089796000000310
wherein, t0Indicates the initial alignment start time, tkIndicating an initial alignment end time;
Figure BDA00029089796000000311
a carrier coordinate system b obtained by a mechanical arrangement algorithm of the strapdown inertial navigation system from t0To tkEstimating the position increment vector of the carrier in a navigation coordinate system n system; definition of
Figure BDA00029089796000000312
Is a b system determined when the roll angle and the pitch angle of the carrier are zero,
Figure BDA00029089796000000313
represents t0Time of flight
Figure BDA00029089796000000314
An attitude rotation matrix estimation value tied to a b system of a carrier coordinate system;
Figure BDA00029089796000000315
represents tkTime of flight
Figure BDA00029089796000000316
An attitude rotation matrix estimation value tied to a b system of a carrier coordinate system;
Figure BDA00029089796000000317
to represent
Figure BDA00029089796000000318
The radius length of the earth tied to the geocentric;
Figure BDA00029089796000000319
a carrier coordinate system b obtained by calculation of a strapdown inertial navigation system is from t0To tkThe attitude change matrix estimation value;
Figure BDA00029089796000000320
expressed in discrete form by the chain rule, specifically defined as:
Figure BDA00029089796000000321
the attitude change matrix of the carrier at the adjacent moment can be obtained by a Rodrigues rotation formula and a 'single sample + previous period' algorithm, and is as follows:
Figure BDA0002908979600000041
Figure BDA0002908979600000042
wherein the content of the first and second substances,
Figure BDA0002908979600000043
is tk-1The angular increment of (a);
Figure BDA0002908979600000044
is tkThe angular increment of (a);
Figure BDA0002908979600000045
is b is from tk-1To tkEquivalent rotation ofA vector;
Figure BDA0002908979600000046
is that
Figure BDA0002908979600000047
The die length of (2);
Figure BDA0002908979600000048
is that
Figure BDA0002908979600000049
The unit direction vector of (1);
Figure BDA00029089796000000410
is an antisymmetric matrix of unit direction vectors;
preferably, the specific calculation process of the heading error angle in the step 4 is as follows:
decomposing the real position increment vector of the carrier from the initial alignment starting time to the initial alignment ending time into a three-dimensional vector form:
Figure BDA00029089796000000411
wherein, t0Indicates the initial alignment start time, tkIndicating an initial alignment end time;
Figure BDA00029089796000000412
is the position increment component of the true position increment vector of the carrier in the direction of true north;
Figure BDA00029089796000000413
is the position increment component of the real position increment vector of the carrier in the direction of the east;
Figure BDA00029089796000000414
is the position increment component of the true position increment vector of the carrier in the vertical direction.
Will t0To tkIncrement of position of carrierVector decomposition into three-dimensional vector form:
Figure BDA00029089796000000415
wherein the content of the first and second substances,
Figure BDA00029089796000000416
the position increment vector estimation value of the carrier is the position increment component of the carrier in the true north direction;
Figure BDA00029089796000000417
is the position increment component of the estimated value of the position increment vector of the carrier in the north east direction;
Figure BDA00029089796000000418
is the position increment component of the position increment vector estimated value of the carrier in the vertical direction.
Definition of n0The coordinate system is composed of t0Is determined by the navigation coordinate system n, n0The coordinate system is a constant coordinate system and does not change along with time;
will be provided with
Figure BDA00029089796000000419
Projecting on n by orthogonal projection method0Is on the XY plane to obtain t0To tkIncrement vector of real position of carrier at n0The projection on the XY plane is:
Figure BDA00029089796000000420
will be provided with
Figure BDA00029089796000000421
Projecting on n by orthogonal projection method0Is on the XY plane to obtain t0To tkVector estimation of position increment of carrier at n0The projection on the XY plane is:
Figure BDA0002908979600000051
equation of
Figure BDA0002908979600000052
Can be written as a three-dimensional nomadic alignment model:
Figure BDA0002908979600000053
because of the three-dimensional vector
Figure BDA0002908979600000054
And
Figure BDA0002908979600000055
the third dimension is zero, and is then rewritten as a two-dimensional vector
Figure BDA0002908979600000056
And
Figure BDA0002908979600000057
the three-dimensional nomadic alignment model can be changed into a two-dimensional nomadic alignment model:
Figure BDA0002908979600000058
the course error angle delta psi can be solved according to the two-dimensional cruise alignment model, so that the initial alignment process of the strapdown inertial navigation system is completed;
the heading error angle Δ ψ can also be calculated by the cosine theorem:
Figure BDA0002908979600000059
wherein
Figure BDA00029089796000000510
The inner product of the vectors is represented as,
Figure BDA00029089796000000511
and
Figure BDA00029089796000000512
representing the modulo length of the vector.
Drawings
FIG. 1: is a carrier coordinate system b system and a transition coordinate system
Figure BDA00029089796000000513
A system and navigation coordinate system n system schematic diagram;
FIG. 2: projecting the real motion trail of the carrier and the motion trail calculated by the INS on a local horizontal geographic coordinate system XY plane;
FIG. 3: an MEMS-level IMU alignment precision-time diagram is obtained;
FIG. 4: a navigation-level IMU alignment accuracy-time diagram.
FIG. 5: the method of the invention is a flow chart.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention relates to a novel initial alignment method for low-cost MEMS-level IMUs in a low-speed moving carrier, and the specific implementation steps of the invention are described in detail below with reference to the accompanying drawings 1 to 5.
A strapdown inertial navigation system that moves over a small area of the earth's surface, i.e., within a radius of no more than 25 meters, has one characteristic: a pure rotation relation exists between the carrier motion track obtained by the calculation of the strap-down inertial navigation system with the initial alignment error and the real motion track of the carrier
Figure BDA0002908979600000061
(
Figure BDA0002908979600000062
Representing the position increment calculated and acquired by the strapdown inertial navigation system,
Figure BDA0002908979600000063
the true position increment of the RTK acquisition is represented,
Figure BDA0002908979600000064
representing a rotation matrix between the two) and the pure rotation error is mainly caused by the initial alignment error. Based on the characteristic of a strapdown inertial navigation system, the method solves the initial alignment error in a reverse mode, and therefore the initial alignment of the low-speed motion carrier is achieved.
The initial alignment method is realized by means of a designed navigation system (see fig. 3), wherein the navigation system is divided into an Inertial Measurement Unit (IMU) sensor which is responsible for raw data acquisition, a GNSS positioning module (such as RTK) and a core processing unit Jetson chip. The inertia measurement unit is used for acquiring original data and transmitting the original data to the core processing unit; the core processing unit is loaded with a strapdown Inertial Navigation System (INS) (namely a program process), inertial navigation original data can be processed to obtain the position information of a carrier, and then the resolved position information is transmitted to an initial alignment algorithm program process; meanwhile, the GNSS positioning module transmits the acquired carrier position information to an initial alignment algorithm program process of the core processing unit, the initial alignment algorithm process receives the position information from the INS navigation system and the navigation information acquired by the GNSS positioning module, a course error angle is solved by utilizing a similarity principle, the solved course error angle is transmitted back to the INS system, and the INS receives the fed-back course error angle and then completes the whole initial alignment process.
The system of the invention comprises: the system comprises a microprocessor, a navigation system and an IMU module;
and the microprocessor is respectively connected with the navigation system and the IMU module in sequence.
The type of the microprocessor is as follows: NVIDIA Jetson TX2 chip;
the navigation system is characterized in that the model is as follows: beidou Haida TS 3;
the IMU module is of the type: ADIS16460 chip;
step 1: the navigation system acquires the latitude of the carrier at the initialization moment and the longitude of the carrier at the initialization moment, acquires the latitude of the carrier at different moments and the longitude of the carrier at different moments, and transmits the latitude of the carrier at the initialization moment, the longitude of the carrier at the initialization moment, the latitude of the carrier at different moments and the longitude of the carrier at different moments to the microprocessor; the IMU module acquires angular velocity increment information of adjacent moments and speed increment information of the adjacent moments, and transmits the angular velocity increment information of the adjacent moments and the speed increment information of the adjacent moments to the microprocessor;
step 1, the latitude of the carrier at the initial alignment time is as follows:
Figure BDA0002908979600000071
wherein the content of the first and second substances,
Figure BDA0002908979600000072
denotes the vector at t0The latitude of the moment;
the longitude of the initial alignment time carrier in the step 1 is as follows:
Figure BDA0002908979600000073
wherein the content of the first and second substances,
Figure BDA0002908979600000074
denotes the vector at t0The longitude of the time of day;
step 1, the latitude of the carrier at different moments is as follows:
Figure BDA0002908979600000075
i∈[1，N]
wherein the content of the first and second substances,
Figure BDA0002908979600000076
denotes the vector at tiLatitude of the moment, N represents the number of the acquisition moments;
the longitude of the carrier at different moments in the step 1 is as follows:
Figure BDA0002908979600000077
i∈[1，N]
wherein the content of the first and second substances,
Figure BDA0002908979600000078
denotes the vector at tiLongitude of the time, N representing the number of acquisition times;
step 1, the angular velocity increment information of the adjacent time is as follows:
Figure BDA0002908979600000079
wherein the content of the first and second substances,
Figure BDA00029089796000000710
denotes the vector from ti-1To tiAngular velocity increment information of the time;
step 1, the speed increment information of the adjacent time is as follows:
Figure BDA00029089796000000711
wherein the content of the first and second substances,
Figure BDA00029089796000000712
denotes the vector from ti-1To tiVelocity increment information of the time;
step 2: the microprocessor selects a proper acquisition time as an initial alignment end time, and calculates a real position increment vector of the carrier from the initial alignment start time to the initial alignment end time;
step 2 calculating t0To tkThe true position increment vector for the carrier is:
Figure BDA00029089796000000713
wherein, t0Indicates the initial alignment start time, tkIndicating an initial alignment end time;
Figure BDA0002908979600000081
the vector coordinate system b representing the acquisition of the navigation system is from t0To tkThe vector of true position increments of the carrier in the navigation coordinate system n,
Figure BDA0002908979600000082
the vector coordinate system b (FIG. 1) acquired for the navigation system is shown at t0Is represented in the navigation coordinate system n (as in figure 1),
Figure BDA0002908979600000083
the vector coordinate system b collected for the navigation system is at tkIn the navigation coordinate system n.
And step 3: the microprocessor obtains the latitude estimated value of the carrier at the initial alignment ending time and the longitude estimated value of the carrier at the initial alignment ending time by using the angle increment information and the speed increment information of adjacent moments through a mechanical arrangement algorithm of a strapdown inertial navigation system, and calculates the position increment vector estimated value of the carrier from the initial alignment starting time to the initial alignment ending time;
step 3 said calculating t0To tkThe position increment vector estimation value of the carrier is as follows:
Figure BDA0002908979600000084
wherein, t0Indicates the initial alignment start time, tkIndicating an initial alignment end time;
Figure BDA0002908979600000085
a carrier coordinate system b obtained by a mechanical arrangement algorithm of the strapdown inertial navigation system from t0To tkEstimating the position increment vector of the carrier in a navigation coordinate system n system; definition of
Figure BDA0002908979600000086
The system (as shown in figure 1) is a b system determined when the roll angle and the pitch angle of the carrier are zero,
Figure BDA0002908979600000087
represents t0Time of flight
Figure BDA0002908979600000088
An attitude rotation matrix estimation value tied to a b system of a carrier coordinate system;
Figure BDA0002908979600000089
represents tkTime of flight
Figure BDA00029089796000000810
An attitude rotation matrix estimation value tied to a b system of a carrier coordinate system;
Figure BDA00029089796000000811
to represent
Figure BDA00029089796000000812
The radius length of the earth tied to the geocentric;
Figure BDA00029089796000000813
a carrier coordinate system b obtained by calculation of a strapdown inertial navigation system is from t0To tkThe attitude change matrix estimation value;
Figure BDA00029089796000000814
expressed in discrete form by the chain rule, specifically defined as:
Figure BDA00029089796000000815
the attitude change matrix of the carrier at the adjacent moment can be obtained by a Rodrigues rotation formula and a 'single sample + previous period' algorithm, and is as follows:
Figure BDA00029089796000000816
Figure BDA00029089796000000817
wherein the content of the first and second substances,
Figure BDA00029089796000000818
is tk-1The angular increment of (a);
Figure BDA00029089796000000819
is tkThe angular increment of (a);
Figure BDA00029089796000000820
is b is from tk-1To tkThe equivalent rotation vector of (2);
Figure BDA00029089796000000821
is that
Figure BDA00029089796000000822
The die length of (2);
Figure BDA00029089796000000823
is that
Figure BDA00029089796000000824
The unit direction vector of (1);
Figure BDA00029089796000000825
is an antisymmetric matrix of unit direction vectors;
and 4, step 4: calculating to obtain a course error angle by using a similarity principle (as shown in FIG. 2) through a real position increment vector of the carrier from the initial alignment starting time to the initial alignment ending time and a position increment vector estimated value of the carrier from the initial alignment starting time to the initial alignment ending time;
and 4, the specific calculation process of the course error angle is as follows:
will t0To tkThe vector of the increment of the real position of the carrier is decomposed into a three-dimensional vector form:
Figure BDA0002908979600000091
wherein the content of the first and second substances,
Figure BDA0002908979600000092
is the position increment component of the true position increment vector of the carrier in the direction of true north;
Figure BDA0002908979600000093
is the position increment component of the real position increment vector of the carrier in the direction of the east;
Figure BDA0002908979600000094
is the position increment component of the true position increment vector of the carrier in the vertical direction.
Will t0To tkThe position increment vector of the carrier is decomposed into a three-dimensional vector form:
Figure BDA0002908979600000095
wherein the content of the first and second substances,
Figure BDA0002908979600000096
the position increment vector estimation value of the carrier is the position increment component of the carrier in the true north direction;
Figure BDA0002908979600000097
is the position increment component of the estimated value of the position increment vector of the carrier in the north east direction;
Figure BDA0002908979600000098
is the position increment component of the position increment vector estimated value of the carrier in the vertical direction.
Definition of n0The coordinate system is composed of t0Is determined by the navigation coordinate system n, n0The coordinate system is a constant coordinate system and does not change along with time;
will be provided with
Figure BDA0002908979600000099
Projecting on n by orthogonal projection method0Is on the XY plane to obtain t0To tkIncrement vector of real position of carrier at n0The projection on the XY plane is:
Figure BDA00029089796000000910
will be provided with
Figure BDA00029089796000000911
Projecting on n by orthogonal projection method0Is on the XY plane to obtain t0To tkVector estimation of position increment of carrier at n0The projection on the XY plane is:
Figure BDA00029089796000000912
equation of
Figure BDA00029089796000000913
Can be written as a three-dimensional nomadic alignment model:
Figure BDA00029089796000000914
because of the three-dimensional vector
Figure BDA00029089796000000915
And
Figure BDA00029089796000000916
the third dimension is zero, and is then rewritten as a two-dimensional vector
Figure BDA0002908979600000101
And
Figure BDA0002908979600000102
the three-dimensional nomadic alignment model can be changed into a two-dimensional nomadic alignment model:
Figure BDA0002908979600000103
the course error angle delta psi can be solved according to the two-dimensional cruise alignment model, so that the initial alignment process of the strapdown inertial navigation system is completed;
the heading error angle Δ ψ can also be calculated by the cosine theorem:
Figure BDA0002908979600000104
wherein
Figure BDA0002908979600000105
The inner product of the vectors is represented as,
Figure BDA0002908979600000106
and
Figure BDA0002908979600000107
representing the modulo length of the vector.
And 5: and (4) the microprocessor feeds back the course error angle obtained in the step (4) to the strapdown inertial navigation system to correct the initial navigation attitude, so that the initial alignment of the navigation system is realized.
The experimental scene of the invention is a common vehicle dynamic scene, and the starting point of the experimental starting track is as follows: latitude of the earth
Figure BDA0002908979600000108
The longitude λ is 114.494431 °, and the height h is 15.152 m. The RTK sampling frequency is 1HZ, and the standard deviation of the positioning observation data is as follows: [0.00990.01270.0221]T. The sampling frequency of both IMUs is 200 HZ. The IMU is installed inside the automobile body and fixedly connected with the automobile, the antenna is installed on the roof, and the lever arm errors between the IMU center and the antenna phase center are about 1 m. In the experimental process, the automobile needs to be accelerated to more than 1.5m/s within 2s and move along a straight line as much as possible. And (4) performing experiments on each IMU, and verifying the feasibility and the accuracy of the algorithm by taking the alignment precision as a measurement index.
The experimental results are as follows:
the alignment accuracy is used as a measure. Taking the experimental data of the first 30s of the MEMS-level IMU, the results are shown in FIG. 3, and it can be seen that the alignment accuracy is lowest within 6-7s, and below 0.8379 degrees (RMS) within 10 s. The experimental data of the navigation-level IMU 60s are intercepted, and as a result, as shown in fig. 4, it can be seen that the alignment accuracy is the lowest within 4-9s, and the alignment accuracy is below 0.2249 degrees (RMS) within 4-9 s. Therefore, the feasibility and the accuracy of the algorithm are verified, and the algorithm is also proved to be applicable under the conditions of MEMS and navigation-level IMU equipment.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (5)

1. A novel initial alignment method for MEMS-level IMU in a low-speed moving carrier is characterized in that:
the MEMS-grade IMU comprises: the system comprises a microprocessor, a navigation system and an IMU module;
the microprocessor is respectively connected with the navigation system and the IMU module in sequence;
the novel initial alignment method comprises the following steps:
step 1: the navigation system acquires the latitude of the carrier at the initialization moment and the longitude of the carrier at the initialization moment, acquires the latitude of the carrier at different moments and the longitude of the carrier at different moments, and transmits the latitude of the carrier at the initialization moment, the longitude of the carrier at the initialization moment, the latitude of the carrier at different moments and the longitude of the carrier at different moments to the microprocessor; the IMU module acquires angular velocity increment information of adjacent moments and speed increment information of the adjacent moments, and transmits the angular velocity increment information of the adjacent moments and the speed increment information of the adjacent moments to the microprocessor;
step 2: the microprocessor selects a proper acquisition time as an initial alignment end time, and calculates a real position increment vector of the carrier from the initial alignment start time to the initial alignment end time;
and step 3: the microprocessor obtains the latitude estimated value of the carrier at the initial alignment ending time and the longitude estimated value of the carrier at the initial alignment ending time by using the angle increment information and the speed increment information of adjacent moments through a mechanical arrangement algorithm of a strapdown inertial navigation system, and calculates the position increment vector estimated value of the carrier from the initial alignment starting time to the initial alignment ending time;
and 4, step 4: calculating to obtain a course error angle through a real position increment vector of the carrier from the initial alignment starting moment to the initial alignment ending moment and a position increment vector estimated value of the carrier from the initial alignment starting moment to the initial alignment ending moment;
and 5: and (4) the microprocessor feeds back the course error angle obtained in the step (4) to the strapdown inertial navigation system to correct the initial navigation attitude, so that the initial alignment of the navigation system is realized.
2. The novel initial alignment method for MEMS-level IMUs in a low-speed motion carrier of claim 1, wherein:
step 1, the latitude of the carrier at the initial alignment time is as follows:
Figure FDA0002908979590000016
wherein the content of the first and second substances,
Figure FDA0002908979590000011
denotes the vector at t0The latitude of the moment;
the longitude of the initial alignment time carrier in the step 1 is as follows:
Figure FDA0002908979590000012
wherein the content of the first and second substances,
Figure FDA0002908979590000013
denotes the vector at t0The longitude of the time of day;
step 1, the latitude of the carrier at different moments is as follows:
Figure FDA0002908979590000014
i∈[1，N]
wherein the content of the first and second substances,
Figure FDA0002908979590000015
denotes the vector at tiLatitude of the moment, N represents the number of the acquisition moments;
the longitude of the carrier at different moments in the step 1 is as follows:
Figure FDA0002908979590000021
i∈[1，N]
wherein the content of the first and second substances,
Figure FDA0002908979590000022
denotes the vector at tiLongitude of the time, N representing the number of acquisition times;
step 1, the angular velocity increment information of the adjacent time is as follows:
Figure FDA0002908979590000023
wherein the content of the first and second substances,
Figure FDA0002908979590000024
denotes the vector from ti-1To tiAngular velocity increment information of the time;
step 1, the speed increment information of the adjacent time is as follows:
Figure FDA0002908979590000025
wherein the content of the first and second substances,
Figure FDA0002908979590000026
denotes the vector from ti-1To tiVelocity delta information for a time instant.
3. The novel initial alignment method for MEMS-level IMUs in a low-speed motion carrier of claim 1, wherein:
step 2 calculating t0To tkThe true position increment vector for the carrier is:
Figure FDA0002908979590000027
wherein, t0Indicates the initial alignment start time, tkIndicating an initial alignment end time;
Figure FDA0002908979590000028
the vector coordinate system b representing the acquisition of the navigation system is from t0To tkThe vector of true position increments of the carrier in the navigation coordinate system n,
Figure FDA0002908979590000029
the vector coordinate system b collected for the navigation system is at t0The representation of the true position vector in the navigation coordinate system n,
Figure FDA00029089795900000210
the vector coordinate system b collected for the navigation system is at tkIn the navigation coordinate system n.
4. The novel initial alignment method for MEMS-level IMUs in a low-speed motion carrier of claim 1, wherein:
step 3, calculating the estimated value of the position increment vector of the carrier from the initial alignment starting time to the initial alignment ending time is as follows:
Figure FDA00029089795900000211
wherein, t0Indicates the initial alignment start time, tkIndicating an initial alignment end time;
Figure FDA00029089795900000212
a carrier coordinate system b obtained by a mechanical arrangement algorithm of the strapdown inertial navigation system from t0To tkEstimating the position increment vector of the carrier in a navigation coordinate system n system; definition of
Figure FDA00029089795900000213
Is a b system determined when the roll angle and the pitch angle of the carrier are zero,
Figure FDA00029089795900000214
represents t0Time of flight
Figure FDA00029089795900000219
An attitude rotation matrix estimation value tied to a b system of a carrier coordinate system;
Figure FDA00029089795900000215
represents tkTime of flight
Figure FDA00029089795900000220
An attitude rotation matrix estimation value tied to a b system of a carrier coordinate system;
Figure FDA00029089795900000216
to represent
Figure FDA00029089795900000217
The radius length of the earth tied to the geocentric;
Figure FDA00029089795900000218
a carrier coordinate system b obtained by calculation of a strapdown inertial navigation system is from t0To tkThe attitude change matrix estimation value;
Figure FDA0002908979590000031
expressed in discrete form by the chain rule, specifically defined as:
Figure FDA0002908979590000032
the attitude change matrix of the carrier at the adjacent moment can be obtained by a Rodrigues rotation formula and a 'single sample + previous period' algorithm, and is as follows:
Figure FDA0002908979590000033
Figure FDA0002908979590000034
wherein the content of the first and second substances,
Figure FDA0002908979590000035
is tk-1The angular increment of (a);
Figure FDA0002908979590000036
is tkThe angular increment of (a);
Figure FDA0002908979590000037
is b is from tk-1To tkThe equivalent rotation vector of (2);
Figure FDA0002908979590000038
is that
Figure FDA0002908979590000039
The die length of (2);
Figure FDA00029089795900000310
is that
Figure FDA00029089795900000311
The unit direction vector of (1);
Figure FDA00029089795900000312
is an antisymmetric matrix of unit direction vectors.
5. The novel initial alignment method for MEMS-level IMUs in a low-speed motion carrier of claim 1, wherein:
and 4, the specific calculation process of the course error angle is as follows:
decomposing the real position increment vector of the carrier from the initial alignment starting time to the initial alignment ending time into a three-dimensional vector form:
Figure FDA00029089795900000313
wherein, t0Indicates the initial alignment start time, tkIndicating an initial alignment end time;
Figure FDA00029089795900000314
is the position increment component of the true position increment vector of the carrier in the direction of true north;
Figure FDA00029089795900000315
is the position increment component of the real position increment vector of the carrier in the direction of the east;
Figure FDA00029089795900000316
is the position increment component of the real position increment vector of the carrier in the vertical direction;
will t0To tkThe position increment vector of the carrier is decomposed into a three-dimensional vector form:
Figure FDA00029089795900000317
wherein the content of the first and second substances,
Figure FDA00029089795900000318
the position increment vector estimation value of the carrier is the position increment component of the carrier in the true north direction;
Figure FDA00029089795900000319
is the position increment component of the estimated value of the position increment vector of the carrier in the north east direction;
Figure FDA00029089795900000320
is the position increment component of the position increment vector estimated value of the carrier in the vertical direction;
definition of n0The coordinate system is composed of t0Is determined by the navigation coordinate system n, n0The coordinate system is a constant coordinate system and does not change along with time;
will be provided with
Figure FDA00029089795900000321
Projecting on n by orthogonal projection method0Is on the XY plane to obtain t0To tkIncrement vector of real position of carrier at n0The projection on the XY plane is:
Figure FDA00029089795900000322
will be provided with
Figure FDA00029089795900000323
Projecting on n by orthogonal projection method0Is on the XY plane to obtain t0To tkVector estimation of position increment of carrier at n0The projection on the XY plane is:
Figure FDA0002908979590000041
equation of
Figure FDA0002908979590000042
Can be written as a three-dimensional nomadic alignment model:
Figure FDA0002908979590000043
because of the three-dimensional vector
Figure FDA0002908979590000044
And
Figure FDA0002908979590000045
the third dimension is zero, and is then rewritten as a two-dimensional vector
Figure FDA0002908979590000046
And
Figure FDA0002908979590000047
the three-dimensional nomadic alignment model can be changed into a two-dimensional nomadic alignment model:
Figure FDA0002908979590000048
the course error angle delta psi can be solved according to the two-dimensional cruise alignment model, so that the initial alignment process of the strapdown inertial navigation system is completed;
the heading error angle Δ ψ can also be calculated by the cosine theorem:
Figure FDA0002908979590000049
wherein
Figure FDA00029089795900000410
The inner product of the vectors is represented as,
Figure FDA00029089795900000411
and
Figure FDA00029089795900000412
representing the modulo length of the vector.
CN202110080286.9A 2021-01-21 2021-01-21 Initial alignment method for MEMS-level IMU in low-speed motion carrier Active CN112902950B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110080286.9A CN112902950B (en) 2021-01-21 2021-01-21 Initial alignment method for MEMS-level IMU in low-speed motion carrier

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110080286.9A CN112902950B (en) 2021-01-21 2021-01-21 Initial alignment method for MEMS-level IMU in low-speed motion carrier

Publications (2)

Publication Number Publication Date
CN112902950A true CN112902950A (en) 2021-06-04
CN112902950B CN112902950B (en) 2022-10-21

Family

ID=76117808

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110080286.9A Active CN112902950B (en) 2021-01-21 2021-01-21 Initial alignment method for MEMS-level IMU in low-speed motion carrier

Country Status (1)

Country Link
CN (1) CN112902950B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114994732A (en) * 2022-08-04 2022-09-02 武汉大学 Vehicle-mounted course rapid initialization device and method based on GNSS carrier phase

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020008661A1 (en) * 2000-07-20 2002-01-24 Mccall Hiram Micro integrated global positioning system/inertial measurement unit system
US20030149528A1 (en) * 2002-02-06 2003-08-07 Ching-Fang Lin Positioning and navigation method and system thereof
CN108759871A (en) * 2018-07-03 2018-11-06 哈尔滨工业大学 A kind of strapdown inertial navigation system coarse alignment method based on improvement EMD Preprocessing Algorithms
CN109931955A (en) * 2019-03-18 2019-06-25 北京工业大学 Strapdown inertial navigation system Initial Alignment Method based on the filtering of state correlation Lie group
CN110702143A (en) * 2019-10-19 2020-01-17 北京工业大学 Rapid initial alignment method for SINS strapdown inertial navigation system moving base based on lie group description
CN112085790A (en) * 2020-08-14 2020-12-15 香港理工大学深圳研究院 Point-line combined multi-camera visual SLAM method, equipment and storage medium

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020008661A1 (en) * 2000-07-20 2002-01-24 Mccall Hiram Micro integrated global positioning system/inertial measurement unit system
US20030149528A1 (en) * 2002-02-06 2003-08-07 Ching-Fang Lin Positioning and navigation method and system thereof
CN108759871A (en) * 2018-07-03 2018-11-06 哈尔滨工业大学 A kind of strapdown inertial navigation system coarse alignment method based on improvement EMD Preprocessing Algorithms
CN109931955A (en) * 2019-03-18 2019-06-25 北京工业大学 Strapdown inertial navigation system Initial Alignment Method based on the filtering of state correlation Lie group
CN110702143A (en) * 2019-10-19 2020-01-17 北京工业大学 Rapid initial alignment method for SINS strapdown inertial navigation system moving base based on lie group description
CN112085790A (en) * 2020-08-14 2020-12-15 香港理工大学深圳研究院 Point-line combined multi-camera visual SLAM method, equipment and storage medium

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
张旭等: "高精度GNSS辅助下MEMS惯导的初始对准方法", 《淮阴工学院学报》 *
许建国 等: "基于DR_GIS组合导航动态对准方法研究", 《计算机测量与控制》 *
陈允芳等: "车载捷联惯导系统定位测姿算法研究", 《中国惯性技术学报》 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114994732A (en) * 2022-08-04 2022-09-02 武汉大学 Vehicle-mounted course rapid initialization device and method based on GNSS carrier phase
CN114994732B (en) * 2022-08-04 2022-11-01 武汉大学 Vehicle-mounted course rapid initialization device and method based on GNSS carrier phase

Also Published As

Publication number Publication date
CN112902950B (en) 2022-10-21

Similar Documents

Publication Publication Date Title
CN100587641C (en) A kind of attitude determination system that is applicable to the arbitrary motion mini system
CN102486377B (en) Method for acquiring initial course attitude of fiber optic gyro strapdown inertial navigation system
CN102393201B (en) Dynamic lever arm compensating method of position and posture measuring system (POS) for aerial remote sensing
CN109974697A (en) A kind of high-precision mapping method based on inertia system
CN104501838B (en) SINS Initial Alignment Method
CN102679978B (en) Initial alignment method of static base of rotary type strap-down inertial navigation system
CN103822633A (en) Low-cost attitude estimation method based on second-order measurement update
CN104697526A (en) Strapdown inertial navitation system and control method for agricultural machines
CN103900565A (en) Method for obtaining inertial navigation system attitude based on DGPS (differential global positioning system)
CN112596089B (en) Fusion positioning method and device, electronic equipment and storage medium
CN111426320A (en) Vehicle autonomous navigation method based on image matching/inertial navigation/milemeter
CN113267794B (en) Antenna phase center correction method and device with base line length constraint
CN110044377B (en) Vicon-based IMU offline calibration method
CN103175528A (en) Strap-down compass gesture measurement method based on strap-down inertial navigation system
CN103389115A (en) Integrated error calibrating method of SINS/DVL (strapdown inertial navigation system/doppler velocity sonar) combined navigation system
CN103454665A (en) Method for measuring double-difference GPS/SINS integrated navigation attitude
JP2014102137A (en) Self position estimation device
CN109764870B (en) Carrier initial course estimation method based on transformation estimation modeling scheme
CN103076026A (en) Method for determining speed measurement error of Doppler velocity log (DVL) in strapdown inertial navigation system
CN102707080B (en) Method for simulating strapdown inertial navigation gyroscope by using star sensor
CN106093992A (en) A kind of sub-meter grade combined positioning and navigating system based on CORS and air navigation aid
CN103575276A (en) Initial alignment model reduction method for biaxial rotation inertial navigation system
CN113503892A (en) Inertial navigation system moving base initial alignment method based on odometer and backtracking navigation
CN112902950B (en) Initial alignment method for MEMS-level IMU in low-speed motion carrier
CN112747770B (en) Speed measurement-based initial alignment method in carrier maneuvering

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant