magnetometers correction and magnetometers-aided
TRANSCRIPT
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 17
Magnetometers Correction and Magnetometers-aided MINS Systems
Based on LabWindowsCVI and MATLAB
Long Wang1 a Xingcheng Li1 b Chuanjun Li1 c and Shuangbiao Zhang1 d
1
Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of Education School ofAerospace Engineering Beijing Institute of Technology Beijing China
azilan862aliyuncom
bxingchlibiteducn
clichuanjunbiteducn
dgodtravel789163com
Keywords LabWindowsCVI MATLAB magnetometer MINS ActiveX virtual Instrument
Abstract Magnetometers-aided MINS could solve roll angle measurement of air vehicle at fast
spinning rate but magnetometers were easily disturbed and had measuring error so it was necessary
to establish tri-axial magnetometer correction system for magnetometers-aided MINS navigation
system Based on LabWindowsCVI and MATLAB fuzzy programming earth magnetic field and
ellipsoid fitting model were built to complete magnetometers correction system and its virtual
instrument On that basic magnetometers-aided MINS navigation system and its virtual instrumentwere established Results of correction and non-correction magnetometers-aided MINS navigation
test showed that the magnetometers correction system can compensate the error of interference
measuring and so on furthermore geomagnetic attitude computing become more accurate and the
higher precision of position and velocity for magnetometers-aided MINS system All of them are
significant for engineering and products
Introduction
Attitude information of air vehicle plays a great importance in navigation system and guidance system
Now inertial device canrsquot satisfy the measuring range of the spin rate for high rotation speed air
vehicle Magnetic sensor has the characteristic of good stability low drift low cost fast response etc
It can measure geomagnetic intensity for solving the attitude of high rotation speed air vehicle which
has been a hot research area [1] However magnetometers measurement include the effective
geomagnetism information the negative information of vehicle ferromagnetic error and own error
The vehicle ferromagnetic error mainly causes by hard magnetic materials and soft magnetic
materials magnetic field The own error causes by sensitivity zero offset and non-orthogonality [2 3]
Excluding the interference and error vehicle arbitrarily rotates at the origin The trace of the
magnetometers measurement about geomagnetism should be sphere surface of which original point
as the center the total geomagnetic intensity as the radius in three-dimensional space Since the
aforementioned interference and error the center of sphere shift and the sphere has aberration
changing to ellipsoid so in this paper magnetometers correction system and its virtual instrumentwere designed to calibrate and compensate composite error for gaining the actual measurement based
on the ellipsoid fitting method
LabWindowsCVI is a software development platform based on ANSI C as core and particularly
suitable for the development of detection data acquisition process monitoring virtual system It uses
event-driven and callback programming methods to implement complex data acquisition and
processing with a wealth of library functions and is easy to learn However in the areas of advanced
theories and methods of geomagnetism monitoring there is no available libraries At the same time
MATLAB has the aforementioned function with the strong capabilities of matrix computation and
data visualization In one hand it can achieve the numerical analysis optimization mathematical
statistics and equation solution in math On the other hand it can deal with a two-dimensional or
three-dimensional graphics image processing and other aspects [4]
This article is aimed at building up magnetometers correction system and its virtual instrument
taking advantage of that LabWindowsCVI collects sensor data MATLAB has powerful math
processing capability and MATLAB has earth magnetic field module Therefore the paper is aimed at
Applied Mechanics and Materials Vols 568-570 (2014) pp 374-379copy (2014) Trans Tech Publications Switzerland doi104028wwwscientificnetAMM568-570374
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 27
building up magnetometers-aided micro inertial navigation system (MINS) and its virtual instrument
utilizing LabWindowsCVI and C language for attitude and navigation computation The virtual
instruments can easily show or store the test data and result In this paper how to realize
LabWindowsCVI and MATLAB fuzzy programming is introduced such as how LabWindowsCVI
call MATLAB here their advantages fully embody for completing the development of
magnetometers correction system
System General Scheme Design
Magnetometers Correction System Fig 1 describes functional block diagram of the
Magnetometers correction system whose virtual instrument was built by LabWindowsCVI and
MATLAB consisting of measuring unit data acquisition unit correction unit load parameters unit
and earth magnetic field model Three-axis magnetic sensor (Magnetic Measurement Unit MMU)
output digital local geomagnetic measurement which were received by data acquisition unit in the PC
via a serial port Data acquisition unit was generated by LabWindowsCVI MATLAB library
function has earth magnetic field model with lsquowrldmagmrsquo function It just needs to be input local
geography information (longitude latitude and altitude) and current time (year month and day) willobtain the geomagnetic information in the locality such as declination inclination geomagnetic total
intensity and so on A group of magnetic data collected by data acquisition unit can be ellipsoid fitted
by correction unit referenced the geomagnetic information with the ellipsoid fitting function But the
lsquowrldmagmrsquo function and the ellipsoid fitting function program and run in the MATLAB workspace
so here LabWindowsCVI must call MATLAB to work Finally the correction coefficients come out
with geomagnetism correction factors and bias that would be downloaded to or save in the vehicle
computer
Figure 1 Magnetometers correction system functional block diagram
Magnetometers-aided MINS System Most inertial measuring products are complete inertial
systems that include a tri-axial gyroscope a tri-axial accelerometer and a tri-axial magnetometer Fig
2 depicts functional block diagram of magnetometers-aided MINS navigation Themagnetometers-aided MINS virtual instrument was built by LabWindowsCVI The IMU and the
MMU both were digital output The sensor output was collected by digital data acquisition module of
the virtual instrument of Magnetometers-aided MINS navigation system via a serial port Before
calculating attitude the tri-axial magnetometers measurement value must be compensated by
equation [5]
H f = CH m - B (1)
Where C is a geomagnetic correction factors matrix of 3x3 B is a geomagnetic correction bias
matrix of 3x1 H m is a magnetometers measuring value and H f is an ideal value to calculate body
attitude The body attitudes are determined only with magnetometers if one attitude angle is knownThe yaw angle changes very little for the high-speed rotatable vehicle so the yaw angle is assumed to
be known or can be calculate from tri-axial gyroscope measuring value Magnetometers-aided
module works out the pitch and roll angles as the input of MINS to correct the attitude calculated by
Applied Mechanics and Materials Vols 568-570 375
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 37
INS With the more accurate attitude INS calculates velocity and position and output them to
guidance system
Figure 2 Magnetometers-aided MINS system functional block diagram
Virtual Instrument Design
Magnetometers correction system virtual instrument Magnetometers correction system virtual
instrument was programmed based on LabWindowsCVI and MATLAB mixed-language
programming Interface functions between LabWindowsCVI and MATLAB make
LabWindowsCVI can call MATLABrsquos functions to run in the MATLAB environment and return the
result to LabWindowsCVI Through building a data exchange service ActiveX LabWindowsCVI
would communicate with MATLAB [6]
ActiveX Generation Firstly in the LabWindowsCVI development environment we chooselsquoToolsrsquo click lsquoCreate ActiveX Controllerrsquo popup lsquoActiveX Controller Wizard-Welcomersquo dialog
click Next popup lsquoActiveX Controller Wizard-Choose Serverrsquo dialog select lsquoMATLAB Application
Type Libraryrsquo on the list click next popup lsquoActiveX Controller Wizard-Configurersquo set target file
name of suffix lsquofprsquo and path such as lsquoMATLABfprsquo Click next popup lsquoActiveX Controller
Wizard-Advanced Optionsrsquo dialog click lsquoAdvance Optionrsquo click lsquoCheck Allrsquo click next popup
lsquoActiveX Controller Wizard-Finishrsquo dialog click lsquoclosersquo at this moment system will automatically
generate five files of lsquoMATLABfp MATLABc MATLABh MATLABobj and MATLABsubrsquo in
the choice target directory
Select menu lsquoEdit-gtAdd Files to Project-gtAll Filesrsquo popup lsquoAdd Files to Projectrsquo dialog choose
the above five file click lsquoOKrsquo to finish At this point ActiveX service function contains the most basicfunctions that LabWindowsCVI and MATLAB use for fuzzy programming
Besides ActiveX NI company specially configures a friendly interface function file of
lsquoMATLAButilcrsquo which is at the directory of lsquo CVI80 Sample ActiveX MATLAB rsquo and make
fuzzy programming more easily
Functions Realization Introduction As shown in Fig 3 firstly click lsquoopen serial portrsquo button to
open the serial port through which MMU connect with PC then the vehicle with MMU respectively
rotates about xyx axis at the constant slow speed Magnetometers correction system collects
geomagnetic measuring data and store in the vehicle computer
Click lsquoLaunch MATLABrsquo to respond the function lsquoMLApp_NewDIMLApp (NULL 1
LOCALE_NEUTRAL 0 ampmMATLAB)rsquo for entering MATLAB work environment secondly Input
the local geography and time onto the panel click lsquoearth magnetic fieldrsquo to respond the function
lsquoRunMatlabCommand (mMATLAB ldquo[mag_t mag_h mag_dec mag_dip mag_f] = wrldmagm
(localinform(1) localinform(2) localinform(3) decyear (localinform(4) localinform(5)
376 Measurement Technology and its Application III
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 47
localinform(6)) lsquo2010rsquo)rdquo)rsquo to get the current earth magnetic field the local geomagnetic information
of which would show on the main panel
Click lsquoCorrectionrsquo button to respond the function lsquoRunMATLABScript (mMATLAB ldquoE
EllipsoidFittingmrdquo)rsquo to ellipsoid fit the collected data for obtaining the correction factors and bias
which can be returned to LabWindowsCVI environment from MATLAB environment using the
function lsquoGetMatrix (mMATLAB ldquomag_trdquo ampmatrixReal ampmatrixImag ampdim1 ampdim2)rsquo andfinally that would be loaded to PC or MINS via the serial port Click lsquoExitrsquo button to quit out of
system running
Figure 3 Magnetometers correction system virtual instrument user interface
Magnetometers-aided MINS virtual instrument Magnetometers-aided MINS Virtual Instrument
was made up with LabWindowsCVI Each button functions were programmed using C language It
provides the functions of sensors data acquisition timing initial alignment navigation showing
graphic and text and saving as shown in Fig 4
Figure 4 Magnetometers-aided MINS virtual instrument user interface
Data acquisition module turn on the switch of the serial port and receive the output of tri-axial
gyroscope tri-axial accelerometer and tri-axial magnetometer
Applied Mechanics and Materials Vols 568-570 377
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 57
Magnetometer-aided module after magnetometerrsquos measuring values are compensated by Eq 1
the bodyrsquos attitude can be determined with the known yaw angle the local declination inclination and
the total density of geomagnetism
In the INS the body attitude update used the tri-axial gyroscope output Then the body attitude
calculated in the Magnetometer-aided module replaces that calculated in the INS Next to estimate the
velocity and the position with the known attitude and the tri-axial accelerometer output The timer setthe sample rate and can be turn on or turn off It can be set initial alignment then turn to navigate The
magnetometer-aided MINS navigation system outputs the attitude velocity and position that all can
be display on the panel
Experimental Verification
In order to verify whether magnetometers correction could improve the performance of MINS based
on geomagnetic attitude-aided magnetometer-aided MINS integrated navigation test respectively
experiment with magnetometers correction and without magnetometers correction The navigation
tests adopt a group of IMU and MMU data that has error that INS update rate is at 500 Hz and that
rotational rate is at 10 rs Flight initial conditions set as latitude of 067020643 rad longitude of201410996 rad altitude of 139471 m the east velocity of 134969 ms the north velocity of 77943
ms the sky velocity of 108213 ms yaw angle of 30deg north by east pitch angle of 35deg and roll angle
of 0deg The IMU and MMU error model is that gyro bias is 75deg h gyro random walk is 05983216radich
accelerometer bias is 9 mg magnetometer bias is plusmn300 nT magnetometer axis non-orthogonality is
025983216 and magnetometer axis misalignment is 05983216
Magnetometers correction test simulation Before MagnetometerMINS integrated navigation test
we need to do magnetometers correction test following the steps of 212 chapter for obtaining
correction factor and bias and preparing them for MagnetometerMINS integrated navigation All the
MMU measuring value approximately distributes into an ellipsoid as shown in Fig 5
Figure 5 Tri-axial Magnetometers correction based on ellipsoid fitting
Magnetometers-aided MINS navigation test simulation Figs 6-7 show the simulation results of
position velocity and attitude errors of magnetometers-aided MINS navigation They present that the
navigation error of the correction magnetometers-aided MINS is smaller than that of the
non-correction magnetometers-aided MINS at the same spinning rate The attitude accuracy of the
correction magnetometers-aided MINS is greatly improved which imply that magnetometers
correction plays a role in the attitude estimation leading to more precise velocity and position
0 10 20 30 40 50 60 70-400
-300
-200
-100
0
100
200
300
400
500
600
X 6779Y 5417
Time (s)
P o s i t i o n E r r o r ( m )
X 6779Y -1455
X 6779Y -3755
Latitude
Longitude
Elevation
0 10 20 30 40 50 60 70-20
-15
-10
-5
0
5
10
15
20
25
30
X 6779Y 2259
Time (s)
V e l o c i t y E r r o r ( m s )
X 6779Y -8213
X 6779Y -1643
East
North
Sky
0 10 20 30 40 50 60 70-05
-04
-03
-02
-01
0
01
02
X 6779
Y -02391
Time (s)
A t t i t u d
e E r r o r ( d e g )
X 6779Y -04596
Yaw
Pitch
0 10 20 30 40 50 60 70-08
-06
-04
-02
0
02
04
06
X 6779Y -0004049
Time (s)
A t t i t u d
e E r r o r ( d e g )
Roll
Figure 6 Magnetometers-aided MINS navigation test with non-correction
378 Measurement Technology and its Application III
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 67
0 10 20 30 40 50 60 70-200
-150
-100
-50
0
50
100
150
X 6779Y 1219
Time (s)
P o s i t i o n E r r o r ( m )
X 6779Y 1055
X 6779Y -1805
Latitude
Longitude
Elevation
0 10 20 30 40 50 60 70-10
-8
-6
-4
-2
0
2
4
X 6779Y 3616
Time (s)
V e l o c i t y E r r o r ( m s )
X 6779Y 3225
X 6779Y -9553
East
North
Sky
0 10 20 30 40 50 60 70-025
-02
-015
-01
-005
0
005
01
X 6779Y -006621
Time (s)
A t t i t u d e E r r o r ( d e g )
X 6779Y -02378
Yaw
Pitch
0 10 20 30 40 50 60 70
-005
0
005
01
015
02
025
X 6779Y 01104
Time (s)
A t t i t u d e E r r o r ( d e g )
X 6144Y 02019
X 5094Y -007565
Roll
Figure 7 Magnetometers-aided MINS navigation test with correction
Conclusions
The ActiveX controller of LabWindowsCVI allowed LabWindowsCVI to call MATLAB to realize
fuzzy programming which made magnetometers correction virtual instrument achievable according
to magnetometers correction system scheme Magnetometers-aided MINS and its virtual instrument
were developed for navigation test It turned out that magnetometers correction test could compensate
error and eliminate interference and magnetometers correction system could improve the
performance of magnetometers-aided MINS for higher precise navigation The visual virtualinstruments were readily exploited handled and convenient for display They had a good engineering
significance in the fields of measurement correction and navigation
Acknowledgements
This work was financially supported by the key laboratory of dynamics and control of flight vehicle
ministry of education school of aerospace engineering Beijing Institute of Technology
References
[1] GX Shi SX Yang and Z Su The Study on Attitude Algorithm of Rolling Projectile UsingGeomagnetic Information Journal of Projectiles Rockets Missiles and Guidance Vol 31
(2011) p 33-38 In Chinese
[2] J Xu The Study on Analysis of Hard Ferromagnetic Materials Interfere Geomagnetic
Measurement and Calibration Technology [D] Nanjing University of Science and Technology
Nanjing (2013) In Chinese
[3] Y Du The Research on Electronic Compass Measurement Error Analysis and Compensation
Technology North University of China Taiyuan (2011) in press In Chinese
[4] YQ Guo C Chen DM Ma and L Li Establishment and Application of High-frequency
Channel Transmission Attenuation Model Based on LabWindowsCVI and MATLAB Journal
of Modern Electronics Technique Vol 34(2011) p 137-142 In Chinese
[5] L Long and H Zhang Automatic and Adaptive Calibration Method of Tri-axial Magnetometer
Chinese Journal of Scientific Instrument Vol 34 (2013) p 161-165 In Chinese
[6] Q Zhang QM Wu D Chen and Y Li ActiveX Creation and Application in the
LabWindowsCVI Journal of Mechanical and Electrical Engineering Technology Vol 35
(2006) p 64-67 In Chinese
[7] R Halir and J Flusser Numerically Stable Direct Least Squares Fitting of Ellipses Proc of the
6th International Conference in Central Europe on Computer Graphics Visualization and
Interactive Digital Media 1998 (WSCG98) University of West Bohemia Press Vol 1(1998) p
125-132
[8] L Qingde and JG Griffiths Least Squares Ellipsoid Specific Fitting Proc Geometric Modeling
and Processing 2004 (GMPrsquo04) IEEE Comput Soc Vol 18 (2004) p335-340
Applied Mechanics and Materials Vols 568-570 379
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 77
C o p y r i g h t o f A p p l i e d M e c h a n i c s amp M a t e r i a l s i s t h e p r o p e r t y o f T r a n s T e c h P u b l i c a t i o n s L t d
a n d i t s c o n t e n t m a y n o t b e c o p i e d o r e m a i l e d t o m u l t i p l e s i t e s o r p o s t e d t o a l i s t s e r v w i t h o u t
t h e c o p y r i g h t h o l d e r s e x p r e s s w r i t t e n p e r m i s s i o n H o w e v e r u s e r s m a y p r i n t d o w n l o a d o r
e m a i l a r t i c l e s f o r i n d i v i d u a l u s e
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 27
building up magnetometers-aided micro inertial navigation system (MINS) and its virtual instrument
utilizing LabWindowsCVI and C language for attitude and navigation computation The virtual
instruments can easily show or store the test data and result In this paper how to realize
LabWindowsCVI and MATLAB fuzzy programming is introduced such as how LabWindowsCVI
call MATLAB here their advantages fully embody for completing the development of
magnetometers correction system
System General Scheme Design
Magnetometers Correction System Fig 1 describes functional block diagram of the
Magnetometers correction system whose virtual instrument was built by LabWindowsCVI and
MATLAB consisting of measuring unit data acquisition unit correction unit load parameters unit
and earth magnetic field model Three-axis magnetic sensor (Magnetic Measurement Unit MMU)
output digital local geomagnetic measurement which were received by data acquisition unit in the PC
via a serial port Data acquisition unit was generated by LabWindowsCVI MATLAB library
function has earth magnetic field model with lsquowrldmagmrsquo function It just needs to be input local
geography information (longitude latitude and altitude) and current time (year month and day) willobtain the geomagnetic information in the locality such as declination inclination geomagnetic total
intensity and so on A group of magnetic data collected by data acquisition unit can be ellipsoid fitted
by correction unit referenced the geomagnetic information with the ellipsoid fitting function But the
lsquowrldmagmrsquo function and the ellipsoid fitting function program and run in the MATLAB workspace
so here LabWindowsCVI must call MATLAB to work Finally the correction coefficients come out
with geomagnetism correction factors and bias that would be downloaded to or save in the vehicle
computer
Figure 1 Magnetometers correction system functional block diagram
Magnetometers-aided MINS System Most inertial measuring products are complete inertial
systems that include a tri-axial gyroscope a tri-axial accelerometer and a tri-axial magnetometer Fig
2 depicts functional block diagram of magnetometers-aided MINS navigation Themagnetometers-aided MINS virtual instrument was built by LabWindowsCVI The IMU and the
MMU both were digital output The sensor output was collected by digital data acquisition module of
the virtual instrument of Magnetometers-aided MINS navigation system via a serial port Before
calculating attitude the tri-axial magnetometers measurement value must be compensated by
equation [5]
H f = CH m - B (1)
Where C is a geomagnetic correction factors matrix of 3x3 B is a geomagnetic correction bias
matrix of 3x1 H m is a magnetometers measuring value and H f is an ideal value to calculate body
attitude The body attitudes are determined only with magnetometers if one attitude angle is knownThe yaw angle changes very little for the high-speed rotatable vehicle so the yaw angle is assumed to
be known or can be calculate from tri-axial gyroscope measuring value Magnetometers-aided
module works out the pitch and roll angles as the input of MINS to correct the attitude calculated by
Applied Mechanics and Materials Vols 568-570 375
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 37
INS With the more accurate attitude INS calculates velocity and position and output them to
guidance system
Figure 2 Magnetometers-aided MINS system functional block diagram
Virtual Instrument Design
Magnetometers correction system virtual instrument Magnetometers correction system virtual
instrument was programmed based on LabWindowsCVI and MATLAB mixed-language
programming Interface functions between LabWindowsCVI and MATLAB make
LabWindowsCVI can call MATLABrsquos functions to run in the MATLAB environment and return the
result to LabWindowsCVI Through building a data exchange service ActiveX LabWindowsCVI
would communicate with MATLAB [6]
ActiveX Generation Firstly in the LabWindowsCVI development environment we chooselsquoToolsrsquo click lsquoCreate ActiveX Controllerrsquo popup lsquoActiveX Controller Wizard-Welcomersquo dialog
click Next popup lsquoActiveX Controller Wizard-Choose Serverrsquo dialog select lsquoMATLAB Application
Type Libraryrsquo on the list click next popup lsquoActiveX Controller Wizard-Configurersquo set target file
name of suffix lsquofprsquo and path such as lsquoMATLABfprsquo Click next popup lsquoActiveX Controller
Wizard-Advanced Optionsrsquo dialog click lsquoAdvance Optionrsquo click lsquoCheck Allrsquo click next popup
lsquoActiveX Controller Wizard-Finishrsquo dialog click lsquoclosersquo at this moment system will automatically
generate five files of lsquoMATLABfp MATLABc MATLABh MATLABobj and MATLABsubrsquo in
the choice target directory
Select menu lsquoEdit-gtAdd Files to Project-gtAll Filesrsquo popup lsquoAdd Files to Projectrsquo dialog choose
the above five file click lsquoOKrsquo to finish At this point ActiveX service function contains the most basicfunctions that LabWindowsCVI and MATLAB use for fuzzy programming
Besides ActiveX NI company specially configures a friendly interface function file of
lsquoMATLAButilcrsquo which is at the directory of lsquo CVI80 Sample ActiveX MATLAB rsquo and make
fuzzy programming more easily
Functions Realization Introduction As shown in Fig 3 firstly click lsquoopen serial portrsquo button to
open the serial port through which MMU connect with PC then the vehicle with MMU respectively
rotates about xyx axis at the constant slow speed Magnetometers correction system collects
geomagnetic measuring data and store in the vehicle computer
Click lsquoLaunch MATLABrsquo to respond the function lsquoMLApp_NewDIMLApp (NULL 1
LOCALE_NEUTRAL 0 ampmMATLAB)rsquo for entering MATLAB work environment secondly Input
the local geography and time onto the panel click lsquoearth magnetic fieldrsquo to respond the function
lsquoRunMatlabCommand (mMATLAB ldquo[mag_t mag_h mag_dec mag_dip mag_f] = wrldmagm
(localinform(1) localinform(2) localinform(3) decyear (localinform(4) localinform(5)
376 Measurement Technology and its Application III
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 47
localinform(6)) lsquo2010rsquo)rdquo)rsquo to get the current earth magnetic field the local geomagnetic information
of which would show on the main panel
Click lsquoCorrectionrsquo button to respond the function lsquoRunMATLABScript (mMATLAB ldquoE
EllipsoidFittingmrdquo)rsquo to ellipsoid fit the collected data for obtaining the correction factors and bias
which can be returned to LabWindowsCVI environment from MATLAB environment using the
function lsquoGetMatrix (mMATLAB ldquomag_trdquo ampmatrixReal ampmatrixImag ampdim1 ampdim2)rsquo andfinally that would be loaded to PC or MINS via the serial port Click lsquoExitrsquo button to quit out of
system running
Figure 3 Magnetometers correction system virtual instrument user interface
Magnetometers-aided MINS virtual instrument Magnetometers-aided MINS Virtual Instrument
was made up with LabWindowsCVI Each button functions were programmed using C language It
provides the functions of sensors data acquisition timing initial alignment navigation showing
graphic and text and saving as shown in Fig 4
Figure 4 Magnetometers-aided MINS virtual instrument user interface
Data acquisition module turn on the switch of the serial port and receive the output of tri-axial
gyroscope tri-axial accelerometer and tri-axial magnetometer
Applied Mechanics and Materials Vols 568-570 377
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 57
Magnetometer-aided module after magnetometerrsquos measuring values are compensated by Eq 1
the bodyrsquos attitude can be determined with the known yaw angle the local declination inclination and
the total density of geomagnetism
In the INS the body attitude update used the tri-axial gyroscope output Then the body attitude
calculated in the Magnetometer-aided module replaces that calculated in the INS Next to estimate the
velocity and the position with the known attitude and the tri-axial accelerometer output The timer setthe sample rate and can be turn on or turn off It can be set initial alignment then turn to navigate The
magnetometer-aided MINS navigation system outputs the attitude velocity and position that all can
be display on the panel
Experimental Verification
In order to verify whether magnetometers correction could improve the performance of MINS based
on geomagnetic attitude-aided magnetometer-aided MINS integrated navigation test respectively
experiment with magnetometers correction and without magnetometers correction The navigation
tests adopt a group of IMU and MMU data that has error that INS update rate is at 500 Hz and that
rotational rate is at 10 rs Flight initial conditions set as latitude of 067020643 rad longitude of201410996 rad altitude of 139471 m the east velocity of 134969 ms the north velocity of 77943
ms the sky velocity of 108213 ms yaw angle of 30deg north by east pitch angle of 35deg and roll angle
of 0deg The IMU and MMU error model is that gyro bias is 75deg h gyro random walk is 05983216radich
accelerometer bias is 9 mg magnetometer bias is plusmn300 nT magnetometer axis non-orthogonality is
025983216 and magnetometer axis misalignment is 05983216
Magnetometers correction test simulation Before MagnetometerMINS integrated navigation test
we need to do magnetometers correction test following the steps of 212 chapter for obtaining
correction factor and bias and preparing them for MagnetometerMINS integrated navigation All the
MMU measuring value approximately distributes into an ellipsoid as shown in Fig 5
Figure 5 Tri-axial Magnetometers correction based on ellipsoid fitting
Magnetometers-aided MINS navigation test simulation Figs 6-7 show the simulation results of
position velocity and attitude errors of magnetometers-aided MINS navigation They present that the
navigation error of the correction magnetometers-aided MINS is smaller than that of the
non-correction magnetometers-aided MINS at the same spinning rate The attitude accuracy of the
correction magnetometers-aided MINS is greatly improved which imply that magnetometers
correction plays a role in the attitude estimation leading to more precise velocity and position
0 10 20 30 40 50 60 70-400
-300
-200
-100
0
100
200
300
400
500
600
X 6779Y 5417
Time (s)
P o s i t i o n E r r o r ( m )
X 6779Y -1455
X 6779Y -3755
Latitude
Longitude
Elevation
0 10 20 30 40 50 60 70-20
-15
-10
-5
0
5
10
15
20
25
30
X 6779Y 2259
Time (s)
V e l o c i t y E r r o r ( m s )
X 6779Y -8213
X 6779Y -1643
East
North
Sky
0 10 20 30 40 50 60 70-05
-04
-03
-02
-01
0
01
02
X 6779
Y -02391
Time (s)
A t t i t u d
e E r r o r ( d e g )
X 6779Y -04596
Yaw
Pitch
0 10 20 30 40 50 60 70-08
-06
-04
-02
0
02
04
06
X 6779Y -0004049
Time (s)
A t t i t u d
e E r r o r ( d e g )
Roll
Figure 6 Magnetometers-aided MINS navigation test with non-correction
378 Measurement Technology and its Application III
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 67
0 10 20 30 40 50 60 70-200
-150
-100
-50
0
50
100
150
X 6779Y 1219
Time (s)
P o s i t i o n E r r o r ( m )
X 6779Y 1055
X 6779Y -1805
Latitude
Longitude
Elevation
0 10 20 30 40 50 60 70-10
-8
-6
-4
-2
0
2
4
X 6779Y 3616
Time (s)
V e l o c i t y E r r o r ( m s )
X 6779Y 3225
X 6779Y -9553
East
North
Sky
0 10 20 30 40 50 60 70-025
-02
-015
-01
-005
0
005
01
X 6779Y -006621
Time (s)
A t t i t u d e E r r o r ( d e g )
X 6779Y -02378
Yaw
Pitch
0 10 20 30 40 50 60 70
-005
0
005
01
015
02
025
X 6779Y 01104
Time (s)
A t t i t u d e E r r o r ( d e g )
X 6144Y 02019
X 5094Y -007565
Roll
Figure 7 Magnetometers-aided MINS navigation test with correction
Conclusions
The ActiveX controller of LabWindowsCVI allowed LabWindowsCVI to call MATLAB to realize
fuzzy programming which made magnetometers correction virtual instrument achievable according
to magnetometers correction system scheme Magnetometers-aided MINS and its virtual instrument
were developed for navigation test It turned out that magnetometers correction test could compensate
error and eliminate interference and magnetometers correction system could improve the
performance of magnetometers-aided MINS for higher precise navigation The visual virtualinstruments were readily exploited handled and convenient for display They had a good engineering
significance in the fields of measurement correction and navigation
Acknowledgements
This work was financially supported by the key laboratory of dynamics and control of flight vehicle
ministry of education school of aerospace engineering Beijing Institute of Technology
References
[1] GX Shi SX Yang and Z Su The Study on Attitude Algorithm of Rolling Projectile UsingGeomagnetic Information Journal of Projectiles Rockets Missiles and Guidance Vol 31
(2011) p 33-38 In Chinese
[2] J Xu The Study on Analysis of Hard Ferromagnetic Materials Interfere Geomagnetic
Measurement and Calibration Technology [D] Nanjing University of Science and Technology
Nanjing (2013) In Chinese
[3] Y Du The Research on Electronic Compass Measurement Error Analysis and Compensation
Technology North University of China Taiyuan (2011) in press In Chinese
[4] YQ Guo C Chen DM Ma and L Li Establishment and Application of High-frequency
Channel Transmission Attenuation Model Based on LabWindowsCVI and MATLAB Journal
of Modern Electronics Technique Vol 34(2011) p 137-142 In Chinese
[5] L Long and H Zhang Automatic and Adaptive Calibration Method of Tri-axial Magnetometer
Chinese Journal of Scientific Instrument Vol 34 (2013) p 161-165 In Chinese
[6] Q Zhang QM Wu D Chen and Y Li ActiveX Creation and Application in the
LabWindowsCVI Journal of Mechanical and Electrical Engineering Technology Vol 35
(2006) p 64-67 In Chinese
[7] R Halir and J Flusser Numerically Stable Direct Least Squares Fitting of Ellipses Proc of the
6th International Conference in Central Europe on Computer Graphics Visualization and
Interactive Digital Media 1998 (WSCG98) University of West Bohemia Press Vol 1(1998) p
125-132
[8] L Qingde and JG Griffiths Least Squares Ellipsoid Specific Fitting Proc Geometric Modeling
and Processing 2004 (GMPrsquo04) IEEE Comput Soc Vol 18 (2004) p335-340
Applied Mechanics and Materials Vols 568-570 379
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 77
C o p y r i g h t o f A p p l i e d M e c h a n i c s amp M a t e r i a l s i s t h e p r o p e r t y o f T r a n s T e c h P u b l i c a t i o n s L t d
a n d i t s c o n t e n t m a y n o t b e c o p i e d o r e m a i l e d t o m u l t i p l e s i t e s o r p o s t e d t o a l i s t s e r v w i t h o u t
t h e c o p y r i g h t h o l d e r s e x p r e s s w r i t t e n p e r m i s s i o n H o w e v e r u s e r s m a y p r i n t d o w n l o a d o r
e m a i l a r t i c l e s f o r i n d i v i d u a l u s e
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 37
INS With the more accurate attitude INS calculates velocity and position and output them to
guidance system
Figure 2 Magnetometers-aided MINS system functional block diagram
Virtual Instrument Design
Magnetometers correction system virtual instrument Magnetometers correction system virtual
instrument was programmed based on LabWindowsCVI and MATLAB mixed-language
programming Interface functions between LabWindowsCVI and MATLAB make
LabWindowsCVI can call MATLABrsquos functions to run in the MATLAB environment and return the
result to LabWindowsCVI Through building a data exchange service ActiveX LabWindowsCVI
would communicate with MATLAB [6]
ActiveX Generation Firstly in the LabWindowsCVI development environment we chooselsquoToolsrsquo click lsquoCreate ActiveX Controllerrsquo popup lsquoActiveX Controller Wizard-Welcomersquo dialog
click Next popup lsquoActiveX Controller Wizard-Choose Serverrsquo dialog select lsquoMATLAB Application
Type Libraryrsquo on the list click next popup lsquoActiveX Controller Wizard-Configurersquo set target file
name of suffix lsquofprsquo and path such as lsquoMATLABfprsquo Click next popup lsquoActiveX Controller
Wizard-Advanced Optionsrsquo dialog click lsquoAdvance Optionrsquo click lsquoCheck Allrsquo click next popup
lsquoActiveX Controller Wizard-Finishrsquo dialog click lsquoclosersquo at this moment system will automatically
generate five files of lsquoMATLABfp MATLABc MATLABh MATLABobj and MATLABsubrsquo in
the choice target directory
Select menu lsquoEdit-gtAdd Files to Project-gtAll Filesrsquo popup lsquoAdd Files to Projectrsquo dialog choose
the above five file click lsquoOKrsquo to finish At this point ActiveX service function contains the most basicfunctions that LabWindowsCVI and MATLAB use for fuzzy programming
Besides ActiveX NI company specially configures a friendly interface function file of
lsquoMATLAButilcrsquo which is at the directory of lsquo CVI80 Sample ActiveX MATLAB rsquo and make
fuzzy programming more easily
Functions Realization Introduction As shown in Fig 3 firstly click lsquoopen serial portrsquo button to
open the serial port through which MMU connect with PC then the vehicle with MMU respectively
rotates about xyx axis at the constant slow speed Magnetometers correction system collects
geomagnetic measuring data and store in the vehicle computer
Click lsquoLaunch MATLABrsquo to respond the function lsquoMLApp_NewDIMLApp (NULL 1
LOCALE_NEUTRAL 0 ampmMATLAB)rsquo for entering MATLAB work environment secondly Input
the local geography and time onto the panel click lsquoearth magnetic fieldrsquo to respond the function
lsquoRunMatlabCommand (mMATLAB ldquo[mag_t mag_h mag_dec mag_dip mag_f] = wrldmagm
(localinform(1) localinform(2) localinform(3) decyear (localinform(4) localinform(5)
376 Measurement Technology and its Application III
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 47
localinform(6)) lsquo2010rsquo)rdquo)rsquo to get the current earth magnetic field the local geomagnetic information
of which would show on the main panel
Click lsquoCorrectionrsquo button to respond the function lsquoRunMATLABScript (mMATLAB ldquoE
EllipsoidFittingmrdquo)rsquo to ellipsoid fit the collected data for obtaining the correction factors and bias
which can be returned to LabWindowsCVI environment from MATLAB environment using the
function lsquoGetMatrix (mMATLAB ldquomag_trdquo ampmatrixReal ampmatrixImag ampdim1 ampdim2)rsquo andfinally that would be loaded to PC or MINS via the serial port Click lsquoExitrsquo button to quit out of
system running
Figure 3 Magnetometers correction system virtual instrument user interface
Magnetometers-aided MINS virtual instrument Magnetometers-aided MINS Virtual Instrument
was made up with LabWindowsCVI Each button functions were programmed using C language It
provides the functions of sensors data acquisition timing initial alignment navigation showing
graphic and text and saving as shown in Fig 4
Figure 4 Magnetometers-aided MINS virtual instrument user interface
Data acquisition module turn on the switch of the serial port and receive the output of tri-axial
gyroscope tri-axial accelerometer and tri-axial magnetometer
Applied Mechanics and Materials Vols 568-570 377
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 57
Magnetometer-aided module after magnetometerrsquos measuring values are compensated by Eq 1
the bodyrsquos attitude can be determined with the known yaw angle the local declination inclination and
the total density of geomagnetism
In the INS the body attitude update used the tri-axial gyroscope output Then the body attitude
calculated in the Magnetometer-aided module replaces that calculated in the INS Next to estimate the
velocity and the position with the known attitude and the tri-axial accelerometer output The timer setthe sample rate and can be turn on or turn off It can be set initial alignment then turn to navigate The
magnetometer-aided MINS navigation system outputs the attitude velocity and position that all can
be display on the panel
Experimental Verification
In order to verify whether magnetometers correction could improve the performance of MINS based
on geomagnetic attitude-aided magnetometer-aided MINS integrated navigation test respectively
experiment with magnetometers correction and without magnetometers correction The navigation
tests adopt a group of IMU and MMU data that has error that INS update rate is at 500 Hz and that
rotational rate is at 10 rs Flight initial conditions set as latitude of 067020643 rad longitude of201410996 rad altitude of 139471 m the east velocity of 134969 ms the north velocity of 77943
ms the sky velocity of 108213 ms yaw angle of 30deg north by east pitch angle of 35deg and roll angle
of 0deg The IMU and MMU error model is that gyro bias is 75deg h gyro random walk is 05983216radich
accelerometer bias is 9 mg magnetometer bias is plusmn300 nT magnetometer axis non-orthogonality is
025983216 and magnetometer axis misalignment is 05983216
Magnetometers correction test simulation Before MagnetometerMINS integrated navigation test
we need to do magnetometers correction test following the steps of 212 chapter for obtaining
correction factor and bias and preparing them for MagnetometerMINS integrated navigation All the
MMU measuring value approximately distributes into an ellipsoid as shown in Fig 5
Figure 5 Tri-axial Magnetometers correction based on ellipsoid fitting
Magnetometers-aided MINS navigation test simulation Figs 6-7 show the simulation results of
position velocity and attitude errors of magnetometers-aided MINS navigation They present that the
navigation error of the correction magnetometers-aided MINS is smaller than that of the
non-correction magnetometers-aided MINS at the same spinning rate The attitude accuracy of the
correction magnetometers-aided MINS is greatly improved which imply that magnetometers
correction plays a role in the attitude estimation leading to more precise velocity and position
0 10 20 30 40 50 60 70-400
-300
-200
-100
0
100
200
300
400
500
600
X 6779Y 5417
Time (s)
P o s i t i o n E r r o r ( m )
X 6779Y -1455
X 6779Y -3755
Latitude
Longitude
Elevation
0 10 20 30 40 50 60 70-20
-15
-10
-5
0
5
10
15
20
25
30
X 6779Y 2259
Time (s)
V e l o c i t y E r r o r ( m s )
X 6779Y -8213
X 6779Y -1643
East
North
Sky
0 10 20 30 40 50 60 70-05
-04
-03
-02
-01
0
01
02
X 6779
Y -02391
Time (s)
A t t i t u d
e E r r o r ( d e g )
X 6779Y -04596
Yaw
Pitch
0 10 20 30 40 50 60 70-08
-06
-04
-02
0
02
04
06
X 6779Y -0004049
Time (s)
A t t i t u d
e E r r o r ( d e g )
Roll
Figure 6 Magnetometers-aided MINS navigation test with non-correction
378 Measurement Technology and its Application III
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 67
0 10 20 30 40 50 60 70-200
-150
-100
-50
0
50
100
150
X 6779Y 1219
Time (s)
P o s i t i o n E r r o r ( m )
X 6779Y 1055
X 6779Y -1805
Latitude
Longitude
Elevation
0 10 20 30 40 50 60 70-10
-8
-6
-4
-2
0
2
4
X 6779Y 3616
Time (s)
V e l o c i t y E r r o r ( m s )
X 6779Y 3225
X 6779Y -9553
East
North
Sky
0 10 20 30 40 50 60 70-025
-02
-015
-01
-005
0
005
01
X 6779Y -006621
Time (s)
A t t i t u d e E r r o r ( d e g )
X 6779Y -02378
Yaw
Pitch
0 10 20 30 40 50 60 70
-005
0
005
01
015
02
025
X 6779Y 01104
Time (s)
A t t i t u d e E r r o r ( d e g )
X 6144Y 02019
X 5094Y -007565
Roll
Figure 7 Magnetometers-aided MINS navigation test with correction
Conclusions
The ActiveX controller of LabWindowsCVI allowed LabWindowsCVI to call MATLAB to realize
fuzzy programming which made magnetometers correction virtual instrument achievable according
to magnetometers correction system scheme Magnetometers-aided MINS and its virtual instrument
were developed for navigation test It turned out that magnetometers correction test could compensate
error and eliminate interference and magnetometers correction system could improve the
performance of magnetometers-aided MINS for higher precise navigation The visual virtualinstruments were readily exploited handled and convenient for display They had a good engineering
significance in the fields of measurement correction and navigation
Acknowledgements
This work was financially supported by the key laboratory of dynamics and control of flight vehicle
ministry of education school of aerospace engineering Beijing Institute of Technology
References
[1] GX Shi SX Yang and Z Su The Study on Attitude Algorithm of Rolling Projectile UsingGeomagnetic Information Journal of Projectiles Rockets Missiles and Guidance Vol 31
(2011) p 33-38 In Chinese
[2] J Xu The Study on Analysis of Hard Ferromagnetic Materials Interfere Geomagnetic
Measurement and Calibration Technology [D] Nanjing University of Science and Technology
Nanjing (2013) In Chinese
[3] Y Du The Research on Electronic Compass Measurement Error Analysis and Compensation
Technology North University of China Taiyuan (2011) in press In Chinese
[4] YQ Guo C Chen DM Ma and L Li Establishment and Application of High-frequency
Channel Transmission Attenuation Model Based on LabWindowsCVI and MATLAB Journal
of Modern Electronics Technique Vol 34(2011) p 137-142 In Chinese
[5] L Long and H Zhang Automatic and Adaptive Calibration Method of Tri-axial Magnetometer
Chinese Journal of Scientific Instrument Vol 34 (2013) p 161-165 In Chinese
[6] Q Zhang QM Wu D Chen and Y Li ActiveX Creation and Application in the
LabWindowsCVI Journal of Mechanical and Electrical Engineering Technology Vol 35
(2006) p 64-67 In Chinese
[7] R Halir and J Flusser Numerically Stable Direct Least Squares Fitting of Ellipses Proc of the
6th International Conference in Central Europe on Computer Graphics Visualization and
Interactive Digital Media 1998 (WSCG98) University of West Bohemia Press Vol 1(1998) p
125-132
[8] L Qingde and JG Griffiths Least Squares Ellipsoid Specific Fitting Proc Geometric Modeling
and Processing 2004 (GMPrsquo04) IEEE Comput Soc Vol 18 (2004) p335-340
Applied Mechanics and Materials Vols 568-570 379
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 77
C o p y r i g h t o f A p p l i e d M e c h a n i c s amp M a t e r i a l s i s t h e p r o p e r t y o f T r a n s T e c h P u b l i c a t i o n s L t d
a n d i t s c o n t e n t m a y n o t b e c o p i e d o r e m a i l e d t o m u l t i p l e s i t e s o r p o s t e d t o a l i s t s e r v w i t h o u t
t h e c o p y r i g h t h o l d e r s e x p r e s s w r i t t e n p e r m i s s i o n H o w e v e r u s e r s m a y p r i n t d o w n l o a d o r
e m a i l a r t i c l e s f o r i n d i v i d u a l u s e
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 47
localinform(6)) lsquo2010rsquo)rdquo)rsquo to get the current earth magnetic field the local geomagnetic information
of which would show on the main panel
Click lsquoCorrectionrsquo button to respond the function lsquoRunMATLABScript (mMATLAB ldquoE
EllipsoidFittingmrdquo)rsquo to ellipsoid fit the collected data for obtaining the correction factors and bias
which can be returned to LabWindowsCVI environment from MATLAB environment using the
function lsquoGetMatrix (mMATLAB ldquomag_trdquo ampmatrixReal ampmatrixImag ampdim1 ampdim2)rsquo andfinally that would be loaded to PC or MINS via the serial port Click lsquoExitrsquo button to quit out of
system running
Figure 3 Magnetometers correction system virtual instrument user interface
Magnetometers-aided MINS virtual instrument Magnetometers-aided MINS Virtual Instrument
was made up with LabWindowsCVI Each button functions were programmed using C language It
provides the functions of sensors data acquisition timing initial alignment navigation showing
graphic and text and saving as shown in Fig 4
Figure 4 Magnetometers-aided MINS virtual instrument user interface
Data acquisition module turn on the switch of the serial port and receive the output of tri-axial
gyroscope tri-axial accelerometer and tri-axial magnetometer
Applied Mechanics and Materials Vols 568-570 377
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 57
Magnetometer-aided module after magnetometerrsquos measuring values are compensated by Eq 1
the bodyrsquos attitude can be determined with the known yaw angle the local declination inclination and
the total density of geomagnetism
In the INS the body attitude update used the tri-axial gyroscope output Then the body attitude
calculated in the Magnetometer-aided module replaces that calculated in the INS Next to estimate the
velocity and the position with the known attitude and the tri-axial accelerometer output The timer setthe sample rate and can be turn on or turn off It can be set initial alignment then turn to navigate The
magnetometer-aided MINS navigation system outputs the attitude velocity and position that all can
be display on the panel
Experimental Verification
In order to verify whether magnetometers correction could improve the performance of MINS based
on geomagnetic attitude-aided magnetometer-aided MINS integrated navigation test respectively
experiment with magnetometers correction and without magnetometers correction The navigation
tests adopt a group of IMU and MMU data that has error that INS update rate is at 500 Hz and that
rotational rate is at 10 rs Flight initial conditions set as latitude of 067020643 rad longitude of201410996 rad altitude of 139471 m the east velocity of 134969 ms the north velocity of 77943
ms the sky velocity of 108213 ms yaw angle of 30deg north by east pitch angle of 35deg and roll angle
of 0deg The IMU and MMU error model is that gyro bias is 75deg h gyro random walk is 05983216radich
accelerometer bias is 9 mg magnetometer bias is plusmn300 nT magnetometer axis non-orthogonality is
025983216 and magnetometer axis misalignment is 05983216
Magnetometers correction test simulation Before MagnetometerMINS integrated navigation test
we need to do magnetometers correction test following the steps of 212 chapter for obtaining
correction factor and bias and preparing them for MagnetometerMINS integrated navigation All the
MMU measuring value approximately distributes into an ellipsoid as shown in Fig 5
Figure 5 Tri-axial Magnetometers correction based on ellipsoid fitting
Magnetometers-aided MINS navigation test simulation Figs 6-7 show the simulation results of
position velocity and attitude errors of magnetometers-aided MINS navigation They present that the
navigation error of the correction magnetometers-aided MINS is smaller than that of the
non-correction magnetometers-aided MINS at the same spinning rate The attitude accuracy of the
correction magnetometers-aided MINS is greatly improved which imply that magnetometers
correction plays a role in the attitude estimation leading to more precise velocity and position
0 10 20 30 40 50 60 70-400
-300
-200
-100
0
100
200
300
400
500
600
X 6779Y 5417
Time (s)
P o s i t i o n E r r o r ( m )
X 6779Y -1455
X 6779Y -3755
Latitude
Longitude
Elevation
0 10 20 30 40 50 60 70-20
-15
-10
-5
0
5
10
15
20
25
30
X 6779Y 2259
Time (s)
V e l o c i t y E r r o r ( m s )
X 6779Y -8213
X 6779Y -1643
East
North
Sky
0 10 20 30 40 50 60 70-05
-04
-03
-02
-01
0
01
02
X 6779
Y -02391
Time (s)
A t t i t u d
e E r r o r ( d e g )
X 6779Y -04596
Yaw
Pitch
0 10 20 30 40 50 60 70-08
-06
-04
-02
0
02
04
06
X 6779Y -0004049
Time (s)
A t t i t u d
e E r r o r ( d e g )
Roll
Figure 6 Magnetometers-aided MINS navigation test with non-correction
378 Measurement Technology and its Application III
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 67
0 10 20 30 40 50 60 70-200
-150
-100
-50
0
50
100
150
X 6779Y 1219
Time (s)
P o s i t i o n E r r o r ( m )
X 6779Y 1055
X 6779Y -1805
Latitude
Longitude
Elevation
0 10 20 30 40 50 60 70-10
-8
-6
-4
-2
0
2
4
X 6779Y 3616
Time (s)
V e l o c i t y E r r o r ( m s )
X 6779Y 3225
X 6779Y -9553
East
North
Sky
0 10 20 30 40 50 60 70-025
-02
-015
-01
-005
0
005
01
X 6779Y -006621
Time (s)
A t t i t u d e E r r o r ( d e g )
X 6779Y -02378
Yaw
Pitch
0 10 20 30 40 50 60 70
-005
0
005
01
015
02
025
X 6779Y 01104
Time (s)
A t t i t u d e E r r o r ( d e g )
X 6144Y 02019
X 5094Y -007565
Roll
Figure 7 Magnetometers-aided MINS navigation test with correction
Conclusions
The ActiveX controller of LabWindowsCVI allowed LabWindowsCVI to call MATLAB to realize
fuzzy programming which made magnetometers correction virtual instrument achievable according
to magnetometers correction system scheme Magnetometers-aided MINS and its virtual instrument
were developed for navigation test It turned out that magnetometers correction test could compensate
error and eliminate interference and magnetometers correction system could improve the
performance of magnetometers-aided MINS for higher precise navigation The visual virtualinstruments were readily exploited handled and convenient for display They had a good engineering
significance in the fields of measurement correction and navigation
Acknowledgements
This work was financially supported by the key laboratory of dynamics and control of flight vehicle
ministry of education school of aerospace engineering Beijing Institute of Technology
References
[1] GX Shi SX Yang and Z Su The Study on Attitude Algorithm of Rolling Projectile UsingGeomagnetic Information Journal of Projectiles Rockets Missiles and Guidance Vol 31
(2011) p 33-38 In Chinese
[2] J Xu The Study on Analysis of Hard Ferromagnetic Materials Interfere Geomagnetic
Measurement and Calibration Technology [D] Nanjing University of Science and Technology
Nanjing (2013) In Chinese
[3] Y Du The Research on Electronic Compass Measurement Error Analysis and Compensation
Technology North University of China Taiyuan (2011) in press In Chinese
[4] YQ Guo C Chen DM Ma and L Li Establishment and Application of High-frequency
Channel Transmission Attenuation Model Based on LabWindowsCVI and MATLAB Journal
of Modern Electronics Technique Vol 34(2011) p 137-142 In Chinese
[5] L Long and H Zhang Automatic and Adaptive Calibration Method of Tri-axial Magnetometer
Chinese Journal of Scientific Instrument Vol 34 (2013) p 161-165 In Chinese
[6] Q Zhang QM Wu D Chen and Y Li ActiveX Creation and Application in the
LabWindowsCVI Journal of Mechanical and Electrical Engineering Technology Vol 35
(2006) p 64-67 In Chinese
[7] R Halir and J Flusser Numerically Stable Direct Least Squares Fitting of Ellipses Proc of the
6th International Conference in Central Europe on Computer Graphics Visualization and
Interactive Digital Media 1998 (WSCG98) University of West Bohemia Press Vol 1(1998) p
125-132
[8] L Qingde and JG Griffiths Least Squares Ellipsoid Specific Fitting Proc Geometric Modeling
and Processing 2004 (GMPrsquo04) IEEE Comput Soc Vol 18 (2004) p335-340
Applied Mechanics and Materials Vols 568-570 379
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 77
C o p y r i g h t o f A p p l i e d M e c h a n i c s amp M a t e r i a l s i s t h e p r o p e r t y o f T r a n s T e c h P u b l i c a t i o n s L t d
a n d i t s c o n t e n t m a y n o t b e c o p i e d o r e m a i l e d t o m u l t i p l e s i t e s o r p o s t e d t o a l i s t s e r v w i t h o u t
t h e c o p y r i g h t h o l d e r s e x p r e s s w r i t t e n p e r m i s s i o n H o w e v e r u s e r s m a y p r i n t d o w n l o a d o r
e m a i l a r t i c l e s f o r i n d i v i d u a l u s e
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 57
Magnetometer-aided module after magnetometerrsquos measuring values are compensated by Eq 1
the bodyrsquos attitude can be determined with the known yaw angle the local declination inclination and
the total density of geomagnetism
In the INS the body attitude update used the tri-axial gyroscope output Then the body attitude
calculated in the Magnetometer-aided module replaces that calculated in the INS Next to estimate the
velocity and the position with the known attitude and the tri-axial accelerometer output The timer setthe sample rate and can be turn on or turn off It can be set initial alignment then turn to navigate The
magnetometer-aided MINS navigation system outputs the attitude velocity and position that all can
be display on the panel
Experimental Verification
In order to verify whether magnetometers correction could improve the performance of MINS based
on geomagnetic attitude-aided magnetometer-aided MINS integrated navigation test respectively
experiment with magnetometers correction and without magnetometers correction The navigation
tests adopt a group of IMU and MMU data that has error that INS update rate is at 500 Hz and that
rotational rate is at 10 rs Flight initial conditions set as latitude of 067020643 rad longitude of201410996 rad altitude of 139471 m the east velocity of 134969 ms the north velocity of 77943
ms the sky velocity of 108213 ms yaw angle of 30deg north by east pitch angle of 35deg and roll angle
of 0deg The IMU and MMU error model is that gyro bias is 75deg h gyro random walk is 05983216radich
accelerometer bias is 9 mg magnetometer bias is plusmn300 nT magnetometer axis non-orthogonality is
025983216 and magnetometer axis misalignment is 05983216
Magnetometers correction test simulation Before MagnetometerMINS integrated navigation test
we need to do magnetometers correction test following the steps of 212 chapter for obtaining
correction factor and bias and preparing them for MagnetometerMINS integrated navigation All the
MMU measuring value approximately distributes into an ellipsoid as shown in Fig 5
Figure 5 Tri-axial Magnetometers correction based on ellipsoid fitting
Magnetometers-aided MINS navigation test simulation Figs 6-7 show the simulation results of
position velocity and attitude errors of magnetometers-aided MINS navigation They present that the
navigation error of the correction magnetometers-aided MINS is smaller than that of the
non-correction magnetometers-aided MINS at the same spinning rate The attitude accuracy of the
correction magnetometers-aided MINS is greatly improved which imply that magnetometers
correction plays a role in the attitude estimation leading to more precise velocity and position
0 10 20 30 40 50 60 70-400
-300
-200
-100
0
100
200
300
400
500
600
X 6779Y 5417
Time (s)
P o s i t i o n E r r o r ( m )
X 6779Y -1455
X 6779Y -3755
Latitude
Longitude
Elevation
0 10 20 30 40 50 60 70-20
-15
-10
-5
0
5
10
15
20
25
30
X 6779Y 2259
Time (s)
V e l o c i t y E r r o r ( m s )
X 6779Y -8213
X 6779Y -1643
East
North
Sky
0 10 20 30 40 50 60 70-05
-04
-03
-02
-01
0
01
02
X 6779
Y -02391
Time (s)
A t t i t u d
e E r r o r ( d e g )
X 6779Y -04596
Yaw
Pitch
0 10 20 30 40 50 60 70-08
-06
-04
-02
0
02
04
06
X 6779Y -0004049
Time (s)
A t t i t u d
e E r r o r ( d e g )
Roll
Figure 6 Magnetometers-aided MINS navigation test with non-correction
378 Measurement Technology and its Application III
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 67
0 10 20 30 40 50 60 70-200
-150
-100
-50
0
50
100
150
X 6779Y 1219
Time (s)
P o s i t i o n E r r o r ( m )
X 6779Y 1055
X 6779Y -1805
Latitude
Longitude
Elevation
0 10 20 30 40 50 60 70-10
-8
-6
-4
-2
0
2
4
X 6779Y 3616
Time (s)
V e l o c i t y E r r o r ( m s )
X 6779Y 3225
X 6779Y -9553
East
North
Sky
0 10 20 30 40 50 60 70-025
-02
-015
-01
-005
0
005
01
X 6779Y -006621
Time (s)
A t t i t u d e E r r o r ( d e g )
X 6779Y -02378
Yaw
Pitch
0 10 20 30 40 50 60 70
-005
0
005
01
015
02
025
X 6779Y 01104
Time (s)
A t t i t u d e E r r o r ( d e g )
X 6144Y 02019
X 5094Y -007565
Roll
Figure 7 Magnetometers-aided MINS navigation test with correction
Conclusions
The ActiveX controller of LabWindowsCVI allowed LabWindowsCVI to call MATLAB to realize
fuzzy programming which made magnetometers correction virtual instrument achievable according
to magnetometers correction system scheme Magnetometers-aided MINS and its virtual instrument
were developed for navigation test It turned out that magnetometers correction test could compensate
error and eliminate interference and magnetometers correction system could improve the
performance of magnetometers-aided MINS for higher precise navigation The visual virtualinstruments were readily exploited handled and convenient for display They had a good engineering
significance in the fields of measurement correction and navigation
Acknowledgements
This work was financially supported by the key laboratory of dynamics and control of flight vehicle
ministry of education school of aerospace engineering Beijing Institute of Technology
References
[1] GX Shi SX Yang and Z Su The Study on Attitude Algorithm of Rolling Projectile UsingGeomagnetic Information Journal of Projectiles Rockets Missiles and Guidance Vol 31
(2011) p 33-38 In Chinese
[2] J Xu The Study on Analysis of Hard Ferromagnetic Materials Interfere Geomagnetic
Measurement and Calibration Technology [D] Nanjing University of Science and Technology
Nanjing (2013) In Chinese
[3] Y Du The Research on Electronic Compass Measurement Error Analysis and Compensation
Technology North University of China Taiyuan (2011) in press In Chinese
[4] YQ Guo C Chen DM Ma and L Li Establishment and Application of High-frequency
Channel Transmission Attenuation Model Based on LabWindowsCVI and MATLAB Journal
of Modern Electronics Technique Vol 34(2011) p 137-142 In Chinese
[5] L Long and H Zhang Automatic and Adaptive Calibration Method of Tri-axial Magnetometer
Chinese Journal of Scientific Instrument Vol 34 (2013) p 161-165 In Chinese
[6] Q Zhang QM Wu D Chen and Y Li ActiveX Creation and Application in the
LabWindowsCVI Journal of Mechanical and Electrical Engineering Technology Vol 35
(2006) p 64-67 In Chinese
[7] R Halir and J Flusser Numerically Stable Direct Least Squares Fitting of Ellipses Proc of the
6th International Conference in Central Europe on Computer Graphics Visualization and
Interactive Digital Media 1998 (WSCG98) University of West Bohemia Press Vol 1(1998) p
125-132
[8] L Qingde and JG Griffiths Least Squares Ellipsoid Specific Fitting Proc Geometric Modeling
and Processing 2004 (GMPrsquo04) IEEE Comput Soc Vol 18 (2004) p335-340
Applied Mechanics and Materials Vols 568-570 379
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 77
C o p y r i g h t o f A p p l i e d M e c h a n i c s amp M a t e r i a l s i s t h e p r o p e r t y o f T r a n s T e c h P u b l i c a t i o n s L t d
a n d i t s c o n t e n t m a y n o t b e c o p i e d o r e m a i l e d t o m u l t i p l e s i t e s o r p o s t e d t o a l i s t s e r v w i t h o u t
t h e c o p y r i g h t h o l d e r s e x p r e s s w r i t t e n p e r m i s s i o n H o w e v e r u s e r s m a y p r i n t d o w n l o a d o r
e m a i l a r t i c l e s f o r i n d i v i d u a l u s e
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 67
0 10 20 30 40 50 60 70-200
-150
-100
-50
0
50
100
150
X 6779Y 1219
Time (s)
P o s i t i o n E r r o r ( m )
X 6779Y 1055
X 6779Y -1805
Latitude
Longitude
Elevation
0 10 20 30 40 50 60 70-10
-8
-6
-4
-2
0
2
4
X 6779Y 3616
Time (s)
V e l o c i t y E r r o r ( m s )
X 6779Y 3225
X 6779Y -9553
East
North
Sky
0 10 20 30 40 50 60 70-025
-02
-015
-01
-005
0
005
01
X 6779Y -006621
Time (s)
A t t i t u d e E r r o r ( d e g )
X 6779Y -02378
Yaw
Pitch
0 10 20 30 40 50 60 70
-005
0
005
01
015
02
025
X 6779Y 01104
Time (s)
A t t i t u d e E r r o r ( d e g )
X 6144Y 02019
X 5094Y -007565
Roll
Figure 7 Magnetometers-aided MINS navigation test with correction
Conclusions
The ActiveX controller of LabWindowsCVI allowed LabWindowsCVI to call MATLAB to realize
fuzzy programming which made magnetometers correction virtual instrument achievable according
to magnetometers correction system scheme Magnetometers-aided MINS and its virtual instrument
were developed for navigation test It turned out that magnetometers correction test could compensate
error and eliminate interference and magnetometers correction system could improve the
performance of magnetometers-aided MINS for higher precise navigation The visual virtualinstruments were readily exploited handled and convenient for display They had a good engineering
significance in the fields of measurement correction and navigation
Acknowledgements
This work was financially supported by the key laboratory of dynamics and control of flight vehicle
ministry of education school of aerospace engineering Beijing Institute of Technology
References
[1] GX Shi SX Yang and Z Su The Study on Attitude Algorithm of Rolling Projectile UsingGeomagnetic Information Journal of Projectiles Rockets Missiles and Guidance Vol 31
(2011) p 33-38 In Chinese
[2] J Xu The Study on Analysis of Hard Ferromagnetic Materials Interfere Geomagnetic
Measurement and Calibration Technology [D] Nanjing University of Science and Technology
Nanjing (2013) In Chinese
[3] Y Du The Research on Electronic Compass Measurement Error Analysis and Compensation
Technology North University of China Taiyuan (2011) in press In Chinese
[4] YQ Guo C Chen DM Ma and L Li Establishment and Application of High-frequency
Channel Transmission Attenuation Model Based on LabWindowsCVI and MATLAB Journal
of Modern Electronics Technique Vol 34(2011) p 137-142 In Chinese
[5] L Long and H Zhang Automatic and Adaptive Calibration Method of Tri-axial Magnetometer
Chinese Journal of Scientific Instrument Vol 34 (2013) p 161-165 In Chinese
[6] Q Zhang QM Wu D Chen and Y Li ActiveX Creation and Application in the
LabWindowsCVI Journal of Mechanical and Electrical Engineering Technology Vol 35
(2006) p 64-67 In Chinese
[7] R Halir and J Flusser Numerically Stable Direct Least Squares Fitting of Ellipses Proc of the
6th International Conference in Central Europe on Computer Graphics Visualization and
Interactive Digital Media 1998 (WSCG98) University of West Bohemia Press Vol 1(1998) p
125-132
[8] L Qingde and JG Griffiths Least Squares Ellipsoid Specific Fitting Proc Geometric Modeling
and Processing 2004 (GMPrsquo04) IEEE Comput Soc Vol 18 (2004) p335-340
Applied Mechanics and Materials Vols 568-570 379
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 77
C o p y r i g h t o f A p p l i e d M e c h a n i c s amp M a t e r i a l s i s t h e p r o p e r t y o f T r a n s T e c h P u b l i c a t i o n s L t d
a n d i t s c o n t e n t m a y n o t b e c o p i e d o r e m a i l e d t o m u l t i p l e s i t e s o r p o s t e d t o a l i s t s e r v w i t h o u t
t h e c o p y r i g h t h o l d e r s e x p r e s s w r i t t e n p e r m i s s i o n H o w e v e r u s e r s m a y p r i n t d o w n l o a d o r
e m a i l a r t i c l e s f o r i n d i v i d u a l u s e
7252019 Magnetometers Correction and Magnetometers-Aided
httpslidepdfcomreaderfullmagnetometers-correction-and-magnetometers-aided 77
C o p y r i g h t o f A p p l i e d M e c h a n i c s amp M a t e r i a l s i s t h e p r o p e r t y o f T r a n s T e c h P u b l i c a t i o n s L t d
a n d i t s c o n t e n t m a y n o t b e c o p i e d o r e m a i l e d t o m u l t i p l e s i t e s o r p o s t e d t o a l i s t s e r v w i t h o u t
t h e c o p y r i g h t h o l d e r s e x p r e s s w r i t t e n p e r m i s s i o n H o w e v e r u s e r s m a y p r i n t d o w n l o a d o r
e m a i l a r t i c l e s f o r i n d i v i d u a l u s e