CN106918352A - A kind of correction of course method of hand-held MEMS magnetometers - Google Patents
A kind of correction of course method of hand-held MEMS magnetometers Download PDFInfo
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- CN106918352A CN106918352A CN201710302355.XA CN201710302355A CN106918352A CN 106918352 A CN106918352 A CN 106918352A CN 201710302355 A CN201710302355 A CN 201710302355A CN 106918352 A CN106918352 A CN 106918352A
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- 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
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Abstract
The invention discloses a kind of hand-held MEMS magnetometers correction of course method, methods described includes following：(1) absolute force in MEMS magnetometer X, Y, Z axis direction is obtained；(2) X, the Y direction absolute force error that cause are inclined by tilt compensation method dressing plate；(3) ellipse fitting is carried out to the geomagnetic data after above-mentioned correction using the least square method under constraints, obtains oval coefficient, X, the true magnetic field intensity of Y-axis after compass calibration obtains compensation；(4) the course angle noise that hand shake is produced is eliminated using sliding-window filtering.The present invention shakes the error for causing by slope compensation, sliding-window filtering amendment platform inclination and hand, with compass calibration means easy and with good noise robustness, so that the magnetometer course precision after correction is better than 1 °, there is application value higher in the indoor and outdoor navigation for having strict demand to course angle.
Description
Technical field
The present invention relates to indoor and outdoor field of locating technology, specifically a kind of correction of course side of hand-held MEMS magnetometers
Method.
Background technology
MEMS (Micro-Electro-Mechanical-System, MEMS) magnetometer is surveyed as a kind of magnetic field
Measuring appratus, course angle is calculated by measuring component of the surrounding magnetic field in three axle magnetometer, with small volume, it is low in energy consumption, into
This is low, reliability is high, course error not with accumulated time the advantages of.But, MEMS magnetometers are easily subject in use
The interference in extraneous bad border, in order to improve course precision, needs to be corrected magnetometer course before the use.
Current MEMS magnetometer error compensation common methods have Poisson model penalty method, based on outside heading reference auxiliary
Compass deviation compensation method, ellipse fitting penalty method etc..Poisson model penalty method, can be using 12 position tumblings or by outside appearance
State reference data carries out the methods such as Least Square Recurrence to determine 12 parameters, and compensation process complex operation is computationally intensive.It is based on
Outside heading reference compensation method, needs outside course as benchmark in trimming process, and compensation effect is good, but in practical application
In often without heading reference as reference, therefore the practicality of the method is poor.Existing oval penalty method is all without magnetic turntable
On tested, preferably, but in actual use, user is typically hand-held measuring apparatus work to compensation effect, due to inclining,
Shake and the interference of external magnetic field can make course produce larger error.
The content of the invention
For the defect that prior art is present, the present invention provides a kind of hand-held MEMS magnetometers correction of course method.Institute
State method and the error for causing is shaken by slope compensation, sliding-window filtering amendment platform inclination and hand, with easy and tool
There are the compass calibration means of good noise robustness so that the magnetometer course precision after correction is better than 1 °, has to course angle
There is application value higher in the indoor and outdoor navigation of strict demand.
The invention mainly includes steps：1. the absolute force in MEMS magnetometer X, Y, Z axis direction is obtained；2. by inclining
Oblique compensation method dressing plate inclines X, the Y direction absolute force error for causing；3. using the least square under constraints
Method carries out ellipse fitting to the geomagnetic data after above-mentioned correction, obtains oval coefficient, X, Y after compass calibration obtains compensation
The true magnetic field intensity of axle；4. the course angle noise that hand shake is produced is eliminated using sliding-window filtering；5. after output calibration
Course angle.
Brief description of the drawings
Fig. 1 is key step flow chart of the invention.
Fig. 2 describes X, the Y-axis geomagnetic data contrast situation in the present invention before and after compass calibration.
Fig. 3 describes to take geomagnetic data the course error contrast situation after Different treatments.
Specific embodiment
The present invention is done below by embodiment is further described in detail, be beneficial to and fully understood to of the invention.
The present embodiment employs a common hand-held MEMS magnetometer for providing basic data, and data are entered in conjunction with the present invention
Row correction, key step is as described below.
Step 1：MEMS magnetometers are started working, and obtain the absolute force H on MEMS magnetometer X, Y, Z axis directionx′、Hy′、
Hz′。
Step 2：By tilt compensation method, X, Y direction ground magnetic strength of the correction MEMS magnetometer platforms caused by inclination
Degree error, X, Y direction absolute force H after being compensatedx、Hy.Existing tilt compensation method can solve problem, herein
A kind of preferred tilt compensation method is especially provided, is expressed as follows：Define the roll angle after MEMS magnetometer platform inclinations and bow
The elevation angle is respectively γ and θ, then X after compensation correction, Y direction absolute force Hx、HyIt is expressed as：Hx=Hx′cosθ+Hy′
sinθcosγ-Hz′sinθcosγ；Hy=Hy′cosγ-Hz′sinγ。
Step 3：Ellipse is carried out to the geomagnetic data after compensation correction in step 2 using the least square method under constraints
Fitting, obtains oval coefficient, X, the true magnetic field intensity of Y-axis after compass calibration obtains compensation.
Magnetic deviation, refers to the angle in sieve north and magnetic north.The error is that system of the MEMS magnetometers when a certain small region uses is missed
Difference, is together decided on by micro- magnetic field environment of magnetometer foozle and local zonule.When using MEMS magnetometers, need to consider
To the Correction Problemss of magnetic deviation.In actual applications, magnetic deviation is the main cause for causing course precise decreasing, and it is divided into Hard Magnetic interference
Disturbed with soft magnetism.Hard Magnetic interference causes mainly due to the permanent magnet material in bad border around, the magnetic field intensity that they are produced
It is considered invariable, i.e., the component on the field projection synthesized by hard magnetic material to three axles of magnetometer is constant.It is soft
The ferromagnetic material that magnetic disturbance is mainly in bad border around causes, and soft magnetic materials does not have magnetic in itself, is influenceed by surrounding magnetic field
After produce magnetic field, its influence degree and direction are relevant with the position of magnetometer, and annoyance level is relevant with direction.
To obtain more preferable compensation effect, the present embodiment provides a kind of compass calibration method of improvement, and main process is as follows
It is described.
MEMS magnetometers be in level and without any error in the case of, magnetometer is horizontally rotated one week and step is gathered
X, the absolute force H of Y-axis after being compensated in rapid 2x、Hy, they are mapped as positive round of the center of circle on origin under coordinate plane；
During due to being disturbed by Hard Magnetic, positive round deviation from origin can be made, disturb bigger deviation more remote；When being disturbed by soft magnetism, positive round can be abnormal
Become oval, disturb bigger distortion more serious.
In plane coordinate system, the ellipse of optional position can be represented using equation of conic section：Wherein：F is constant, K=(A, B, C, D, E, F)T,The K oval coefficient matrixes as to be solved；As the sample point P of collectionj(Xj,Yj)
During number N >=5 (wherein j=1,2,3, N), according to least square method, you can it is determined that oval coefficient A, B, C, D, E, F
Value.
The conic section obtained using the fitting of Direct Least Square method is not necessarily ellipse, so needing according to elliptic curve
Property, plus constraints with the curve that ensures to fit be oval while fitted ellipse, choose 4AB-C2=1 conduct
The constraints of ellipse fitting, oval coefficient solution seeks extreme-value problem under being converted into constraints：
Wherein：
According to lagrange's method of multipliers, parameter lambda is introduced, formula (1) is converted into the extreme-value problem solved under constraints：
Obtain (DTD, C) 6 generalized eigenvalues and corresponding characteristic vector, in characteristic value only one of which be more than 0, it is required
Oval coefficient matrix K is characterized value more than 0 corresponding characteristic vector, so as to obtain oval coefficient A, B, C, D, E, F.
Compass calibration process is exactly that the ellipse for deviateing the center of circle is corrected to positive round, and its process can be described as：
In formula：Ly=
A/B；It is the X after slope compensation, Y direction earth magnetism
Intensity；By formula (3) can draw X, Y-axis compensate after true absolute force value be：
Step 4：The course angle noise that hand shake is produced is eliminated using sliding-window filtering.
The course angle that MEMS magnetometers are calculated is the angle α of direction of advance and magnetic north.After step 3 compass calibration is compensated
X, the true absolute force value of Y-axis can obtain α：
Referenced north refers to geographic north, magnetic north and geographic north and misaligned, the folder between them in actual applications
Angle is referred to as magnetic declination β, and local magnetic declination β can be by acquisition of tabling look-up.Therefore, in actual use, true course angle ψ=α+
β。
MEMS magnetometers, due to the shake of hand, can cause system vibration in experimentation, so magnetometer is in data
During collection in addition to hard magnetic material and soft magnetic materials can be subject to disturb, also noise can be produced because of the shake of hand.Hand
Shaking the noise for producing can be improved by sliding-window filtering：
Wherein：2N+1 is the length of sliding window, is determined by the sample frequency of magnetometer.Step
5：Course angle ψ after output calibrationi。
Verified present invention employs 3 axis MEMS magnetometer (HMC5883L), in experimentation, used keil softwares
Carry out C language programming, by quaternary number attitude algorithm and Kalman filtering draw accurate roll angle, the angle of pitch, course angle and
The original geomagnetic data of three axles, and exported to host computer by serial ports and preserve into Excel file form.
In order to be analyzed to the course error before and after correction, compass calibration algorithm is realized in Matlab, is read first
Data in Excel forms, the input that roll angle, the angle of pitch are repaid as inclination, course angle is navigated as the reference of error analysis
To.Three axle magnetometer data carry out compass calibration, sliding-window filtering after slope compensation and reject jittering noise, finally export
Course angle after correction.
Compass calibration is contrasted with without compass calibration X, Y-axis geomagnetic data, comparing result as shown in Fig. 2 from
Fig. 2 can be seen that without compass calibration directly fit be deviation from origin ellipse, become by ellipse after compass calibration
The center of circle illustrates that compass calibration method of the invention is exactly accurate in the positive round of origin.
Course error before and after compass calibration is contrasted with the course error before and after filtering.Comparing result such as Fig. 3
It is shown, from figure 3, it can be seen that the course angle obtained using the geomagnetic data without compass calibration and unfiltered (dotted line), due to
The influence of neighbouring hard magnetic material, soft magnetic materials and hand jittering noise, its course error is about ± 31 °.Using by magnetic deviation school
Just and unfiltered (pecked line) the course angle obtained of geomagnetic data, its course error has larger improvement, but magnetic force compared to the former
Meter due to the presence of hand jittering noise, makes course precision produce larger deviation in rotary course, its boat in rotary course
It is about ± 11 ° to error.The course angle obtained using the geomagnetic data by compass calibration and filtering (heavy line), due to shake
Noise is effectively limited, and its course error is reduced within ± 1 °.
Claims (4)
1. a kind of correction of course method of hand-held MEMS magnetometers, methods described includes：
(1) the absolute force H ' on the MEMS magnetometer X, Y, Z axis direction after starting working is obtainedx、H′y、H′z；
(2) by tilt compensation method, X, Y direction absolute force error of the correction MEMS magnetometer platforms caused by inclination,
X, Y direction absolute force H after being compensatedx、Hy；
(3) ellipse fitting is carried out to the geomagnetic data after correction using the least square method under constraints, obtains oval coefficient,
The true absolute force of X, Y-axis after being compensated by compass calibration.
2. method according to claim 1, wherein the tilt compensation method is：After defining MEMS magnetometer platform inclinations
Roll angle and the angle of pitch be respectively γ and θ, then correct after X, Y direction absolute force Hx、HyIt is expressed as：Hx=H 'xcosθ+H′ysinθcosγ-H′zsinθcosγ；
Hy=H 'ycosγ-H′zsinγ。
3. method according to claim 1, wherein described compass calibration comprises the following steps：(1) by MEMS magnetometers
At least horizontally rotate one week and X, Y direction absolute force H after acquisition correctionx、Hy；(2) ellipse of definition optional position is：Wherein：F is constant, K=(A, B, C, D, E, F)T,K is oval coefficient matrix；(3) oval coefficient A, B, C, D, E, F are calculated；(4) magnetic deviation
The true absolute force value after X, Y-axis compensation is obtained after correction is：
Wherein：Ly=A/B；
4. the method according to claim 1,2 or 3, also shakes the boat for producing including eliminating hand using sliding-window filtering
To angle noise.
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Cited By (9)
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| CN107703469A (en) * | 2017-08-25 | 2018-02-16 | 广州新维感信息技术有限公司 | A kind of magnetic force meter calibration method and device |
| CN107830861A (en) * | 2017-12-07 | 2018-03-23 | 智灵飞（北京）科技有限公司 | Based on adaptive gain complementary filter moving object attitude measurement method and device |
| CN109211271A (en) * | 2018-09-11 | 2019-01-15 | 华南理工大学 | A kind of magnetic compass automatic correcting method |
| CN109781107A (en) * | 2017-11-15 | 2019-05-21 | 北京自动化控制设备研究所 | A kind of low precision inertial navigation roll angle determines method |
| WO2019104532A1 (en) * | 2017-11-29 | 2019-06-06 | 歌尔科技有限公司 | Magnetometer data processing method and apparatus |
| CN110530397A (en) * | 2019-08-08 | 2019-12-03 | 北京首贝科技发展有限公司 | A kind of magnetic field automatic calibration method based on nine axis IMU |
| CN113624219A (en) * | 2021-07-27 | 2021-11-09 | 北京理工大学 | Magnetic compass ellipse fitting error compensation method based on OPTICS algorithm |
| CN113884105A (en) * | 2021-09-27 | 2022-01-04 | 陕西航天时代导航设备有限公司 | Disc calibration method for magnetometer calibration |
| CN114485636A (en) * | 2022-01-18 | 2022-05-13 | 中国人民解放军军事科学院国防科技创新研究院 | Bionic compass |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107703469A (en) * | 2017-08-25 | 2018-02-16 | 广州新维感信息技术有限公司 | A kind of magnetic force meter calibration method and device |
| CN109781107A (en) * | 2017-11-15 | 2019-05-21 | 北京自动化控制设备研究所 | A kind of low precision inertial navigation roll angle determines method |
| WO2019104532A1 (en) * | 2017-11-29 | 2019-06-06 | 歌尔科技有限公司 | Magnetometer data processing method and apparatus |
| CN107830861A (en) * | 2017-12-07 | 2018-03-23 | 智灵飞（北京）科技有限公司 | Based on adaptive gain complementary filter moving object attitude measurement method and device |
| CN109211271A (en) * | 2018-09-11 | 2019-01-15 | 华南理工大学 | A kind of magnetic compass automatic correcting method |
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| CN110530397A (en) * | 2019-08-08 | 2019-12-03 | 北京首贝科技发展有限公司 | A kind of magnetic field automatic calibration method based on nine axis IMU |
| CN113624219A (en) * | 2021-07-27 | 2021-11-09 | 北京理工大学 | Magnetic compass ellipse fitting error compensation method based on OPTICS algorithm |
| CN113884105A (en) * | 2021-09-27 | 2022-01-04 | 陕西航天时代导航设备有限公司 | Disc calibration method for magnetometer calibration |
| CN114485636A (en) * | 2022-01-18 | 2022-05-13 | 中国人民解放军军事科学院国防科技创新研究院 | Bionic compass |
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