CN104613983A - Whole machine magnetometer calibration method applied to micro unmanned plane - Google Patents

Abstract

The invention provides a whole machine magnetometer calibration method applied to a micro unmanned plane. The method comprises the following steps: integrating outside hard magnetic interference with null bias errors of a magnetometer, integrating outside soft magnetic interference with sensitivity errors of the magnetometer, carrying out ellipsoid fitting calculation on magnetic interference errors and magnetometer sensor errors, calculating a rotary error matrix of mounting errors by combining with the attitude information of the micro unmanned plane according to a calculation result; and finally calculating calibration parameters of the magnetometer under the condition with the whole micro unmanned plane according to simultaneous error parameters. The calibration parameters of the magnetometer are integrated with environment magnetic interference parameters, sensor error parameters and mounting error parameters. The method has the characteristics of high integration degree, high engineering applicability and high calibration accuracy.

Description

A kind of complete machine magnetometer calibration steps being applied to Small and micro-satellite

Technical field

The invention belongs to detection field, be specifically related to a kind of complete machine magnetometer calibration steps being applied to Small and micro-satellite, can in line computation Small and micro-satellite the calibration parameter of magnetometer, obtain the accurate output of magnetometer under complete machine condition.

Background technology

Magnetometer due to the advantage in its size, weight, power consumption, and by combining with inertial navigation system, can revise the course information of navigational system in real time, eliminates course cumulative errors, is widely adopted in Small and micro-satellite navigational system.

The course precision that magnetometer exports in Small and micro-satellite mainly affects by factor in three.One is the sensor error that magnetometer self exists, and comprises transducer zeroing deviation, sensitivity error, orthogonal error etc.; Two is environment magnetic interference error, Small and micro-satellite small volume, and airborne equipment electromagnetic environment is complicated, introduces stronger Hard Magnetic interference and disturbs with soft magnetism, make magnetometer working environment comparatively severe; Three is the alignment error of magnetometer, because in Small and micro-satellite, magnetometer size is less, without strict frock, usually and body axis system there is larger alignment error.How eliminating and to weaken the impact of these errors on magnetometer, is the key improving course precision.

The calibration steps of current magnetometer divides by demarcation condition and mainly contains without the off-line calibration under magnetic turntable and the on-line proving that there is magnetic interference, divides mainly contain Multiple station method and ellipsoid fitting method etc. by scaling method.Off-line calibration for be the error parameter of magnetometer sensor self, calibration process is comparatively complicated, demarcates that efficiency is low, cost is high, and still needs magnetic interference equal error to external world again to demarcate in using in Small and micro-satellite.On-line proving allows there is being the demarcation carrying out magnetometer under magnetic environment, magnetic interference error to external world can make effective compensation, but due in Small and micro-satellite, magnetometer working environment is comparatively special, common online calibration method fails to carry out effective compensation to all error sources, cause magnetometer to export course precision not high, the needs of the actual use of Small and micro-satellite cannot be met.

Summary of the invention

Technical matters to be solved by this invention is: demarcate complicated for magnetometer in Small and micro-satellite, the situation that calibrating parameters is incomplete, incorporate the main error parameter of magnetometer at Small and micro-satellite, integration, in line computation calibration parameter, improves demarcation efficiency and the output accuracy of magnetometer in Small and micro-satellite.

The present invention includes following technical scheme:

Be applied to a complete machine magnetometer calibration steps for Small and micro-satellite, incorporate the three class errors of magnetometer in Small and micro-satellite, error mainly comprises environment magnetic interference error, sensor error and alignment error.

Magnetic interference error mainly comprises Hard Magnetic interference and disturbs two kinds with soft magnetism, is caused respectively by airborne hard magnetic material and soft magnetic material.

Sensor error mainly comprises zero inclined error of magnetometer, sensitivity error, orthogonal error.

Alignment error is the rotation error matrix between the sensor coordinate system of magnetometer and the body axis system of Small and micro-satellite, causes primarily of artificially installing reason, frock error etc.

Because in Small and micro-satellite, magnetometer position immobilizes relative to body position, namely relative magmetometer position, body magnetic interference source immobilizes, therefore, the present invention is by the zero inclined error correction of extraneous Hard Magnetic interference with magnetometer, extraneous soft magnetism interference is integrated with the sensitivity error of magnetometer, to magnetic interference error, magnetometer sensor error is unified carries out ellipsoid fitting calculating, simultaneously according to result of calculation, in conjunction with the attitude information of Small and micro-satellite, calculate the rotation error matrix of alignment error, finally, error parameter required by simultaneous, calculate for the magnetometer calibration parameter under Small and micro-satellite complete machine condition.

The present invention has the following advantages compared to existing technology:

(1) the present invention carries out magnetometer calibration under Small and micro-satellite complete machine condition, and integrated degree is high, and engineering adaptability is strong;

(2) the present invention fully takes into account magnetometer working environment comparatively special in Small and micro-satellite, compensates the various errors under complete machine condition, and specific aim is stronger, and error parameter is more complete;

(3) scaling method of the present invention is flexible, and for situations such as the change of Micro Aerial Vehicle layout, the changes of magnetometer installation parameter, selectively again can demarcate the parameter of corresponding changing section, without the need to again demarcating, execution efficiency is high;

(4) the present invention is to no requirement (NR)s such as frocks, and can calibrate under hand-held condition, and simple to operate, feasibility is high.

Accompanying drawing explanation

Fig. 1 is the FB(flow block) that the present invention is applied to the complete machine magnetometer calibration steps of Small and micro-satellite;

The rotation schematic diagram (the present invention is adopted coordinate system to be sky, northeast coordinate system) that Fig. 2 is Small and micro-satellite in calibration process of the present invention;

Fig. 3 is the sensor coordinate system of magnetometer and alignment error schematic diagram (the wherein coordinate system Ox of Small and micro-satellite body axis system _by _bz _bfor Small and micro-satellite body axis system, O _xmYmZmfor magnetometer sensor coordinate system).

Embodiment

Below in conjunction with accompanying drawing, the present invention is described further.

Before demarcation is carried out, need to power on to unmanned plane complete machine, make the working environment in the calibration environment of magnetometer and flight course close.

In calibration process, Small and micro-satellite is rotated according to mode shown in Fig. 2, to guarantee calibration accuracy.Unmanned plane is by detecting sensor state at corresponding Posture acquisition magnetometer data, and the error parameter carrying out corresponding process resolves, and relevant control instruction is sent by unmanned aerial vehicle station, see Fig. 1, realizes the complete machine magnetometer on-line calibration to Small and micro-satellite.Calibration content comprises: extraneous magnetic interference and magnetometer sensor error parameter calculate, and alignment error parameter calculates, and complete machine error parameter is integrated.

Specific implementation method is as follows:

One, the parameter of extraneous magnetic interference and magnetometer sensor error calculates

The present invention is by the zero inclined error correction of extraneous Hard Magnetic interference with magnetometer, and extraneous soft magnetism interference is integrated with the sensitivity error of magnetometer, carries out ellipsoid fitting calculating to magnetic interference error, magnetometer sensor error simultaneously.

First Small and micro-satellite is carried out multiposition rotation around magnetometer XYZ tri-axle respectively, as shown in Figure 2, in record rotary course, magnetometer exports rotation mode:

$M^0=\left\{\begin{array}{cccc}{m}_{x1}^0& m_{x2}^0& \·\·\·& m_{\mathrm{xn}}^0\\ m_{y1}^0& m_{y2}^0& \·\·\·& m_{\mathrm{yn}}^0\\ m_{z1}^0& m_{z2}^0& \·\·\·& m_{\mathrm{zn}}^2\end{array}\right\}$

Wherein the raw data measured for i-th time for magnetometer XYZ tri-axle exports.

Recursive least-squares is utilized to calculate calibration parameter under extraneous magnetic interference and the acting in conjunction of magnetometer sensor error according to ellipsoid fitting formula.

$\left[\begin{array}{c}{m}_x\\ m_y\\ m_z\end{array}\right]=\left[\begin{array}{ccc}\frac{\cos \mathrm{\α}\cos \mathrm{\β}}{k_x}& 0& 0\\ \frac{\cos \mathrm{\α}\cos \mathrm{\β}}{k_x}& \frac{\cos \mathrm{\α}}{k_y}& 0\\ \frac{\sin \mathrm{\γ}}{k_x}& \frac{\sin \mathrm{\α}}{k_y}& \frac{1}{k_z}\end{array}\right]\left[\begin{array}{c}{m}_x^0-m_{\mathrm{bx}}\\ m_y^2-m_{\mathrm{by}}\\ m_z^0-m_{\mathrm{bz}}\end{array}\right]$

$m_x^2+m_y^2+m_z^2=M^2$

Wherein, k _x, k _y, k _zfor the sensitivity error factor, α, beta, gamma is the non-orthogonal error angle of between centers, for the original output of magnetometer, m _bx, m _by, m _bzbe zero inclined error, m _x, m _y, m _zfor magnetometer after preliminary corrections exports, M is for work as geomagnetic field intensity.

After having calibrated, unmanned plane record k _x, k _y, k _z, α, beta, gamma, m _bx, m _by, m _bz9 parameters, start the calculating of alignment error parameter by land station's instruction

Two, alignment error parameter calculates

If magnetometer sensor coordinate system m departs from the fleet angle φ of unmanned plane body axis system b _x, φ _y, φ _z, as shown in Figure 3, suppose φ _x, φ _y, φ _zbe little angle, then alignment error matrix can be expressed as:

$C_b^m=\left[\begin{array}{ccc}1& {\mathrm{\φ}}_z& {\mathrm{\φ}}_y\\ -{\mathrm{\φ}}_x& 1& {\mathrm{\φ}}_x\\ {\mathrm{\φ}}_y& -{\mathrm{\φ}}_x& 1\end{array}\right]$

Again Small and micro-satellite is carried out multiposition rotation around magnetometer XYZ tri-axle respectively, as shown in Figure 2, calculate parameters obtained k according to step one _x, k _y, k _z, α, beta, gamma, m _bx, m _by, m _bz, the magnetometer after correcting in record rotary course exports:

$M^{\′}=\left\{\begin{array}{cccc}{m}_{x1}& m_{x2}& \·\·\·& m_{\mathrm{xn}}\\ m_{y1}& m_{y2}& \·\·\·& m_{\mathrm{yn}}\\ m_{z1}& m_{z2}& \·\·\·& m_{\mathrm{zn}}\end{array}\right\}$

Wherein m _xi, m _yi, m _zi, (i=1,2,3 ... n) for the data after i-th measurement update of magnetometer XYZ tri-axle export.

Utilize the attitude data roll angle of Small and micro-satellite pitching angle theta, course angle ψ (can be any heading reference), utilize least square method of recursion to calculate to alignment error matrix parameter.

$C_m^b=C_b^{m^T}$

Wherein, m _x, m _y, m _zfor after step one correction, magnetometer exports, M _x, M _y, M _zfor terrestrial magnetic field component under navigational coordinate system, for sensor alignment error matrix to be measured.

After having calibrated, unmanned plane record φ _x, φ _y, φ _z3 parameters, start the calculating of complete machine error parameter by land station's instruction

Three, complete machine error parameter is integrated

For avoiding the matrix computations of repetition, need to carry out conformity calculation to the error parameter of step one, step 2 calculating gained, the magnetometer error parameter of final Small and micro-satellite complete machine is error matrix C _total, zero inclined error M _b.

$C_{\mathrm{total}}=\left[\begin{array}{ccc}1& -{\mathrm{\φ}}_z& {\mathrm{\φ}}_y\\ {\mathrm{\φ}}_z& 1& -{\mathrm{\φ}}_x\\ -{\mathrm{\φ}}_y& {\mathrm{\φ}}_x& 1\end{array}\right]\left[\begin{array}{ccc}\frac{\cos \mathrm{\α}\cos \mathrm{\β}}{k_x}& 0& 0\\ \frac{\cos \mathrm{\α}\sin \mathrm{\β}}{k_x}& \frac{\cos \mathrm{\α}}{k_y}& 0\\ \frac{\sin \mathrm{\γ}}{k_x}& \frac{\sin \mathrm{\α}}{k_y}& \frac{1}{k_z}\end{array}\right]$

$M_b=\left[\begin{array}{c}{m}_{\mathrm{bx}}\\ m_{\mathrm{by}}\\ m_{\mathrm{bz}}\end{array}\right]$

After completing above step, Small and micro-satellite completes the magnetometer calibration process of complete machine, by parameter C _total, M _bcomplete the output calibration to magnetometer.

M _cal＝C _total·(M ₀-M _b)

Wherein, M _calfor after complete machine calibration, magnetometer exports, M ₀for the original output of magnetometer.

Magnetometer calibration parameter of the present invention incorporates environment magnetic interference parameter, sensor error parameter and alignment error parameter three major types error parameter.It is high that the method possesses integrated degree, and engineering adaptability is strong, calibration accuracy high.

Claims (7)

1. one kind is applied to the complete machine magnetometer calibration steps of Small and micro-satellite, it is characterized in that, described method is by the zero inclined error correction of extraneous Hard Magnetic interference with magnetometer, extraneous soft magnetism interference is integrated with the sensitivity error of magnetometer, ellipsoid fitting calculating is carried out to magnetic interference error, the unification of magnetometer sensor error, simultaneously according to result of calculation, in conjunction with the attitude information of Small and micro-satellite, calculate the rotation error matrix of alignment error, finally, error parameter required by simultaneous, calculates for the magnetometer calibration parameter under Small and micro-satellite complete machine condition.

2. method according to claim 1, is characterized in that, described method specifically comprises:

1) calculating of the calibration parameter under extraneous magnetic interference and magnetometer sensor acting in conjunction;

2) calculating of alignment error parameter;

3) integration of complete machine error parameter.

3. calibration steps according to claim 2, is characterized in that, described step 1) be specially:

11) Small and micro-satellite is carried out multiposition rotation around magnetometer XYZ tri-axle respectively, in record rotary course, magnetometer exports:

$M^0=\left\{\begin{array}{cccc}{m}_{x1}^0& m_{x2}^0& \·\·\·& m_{\mathrm{xn}}^0\\ m_{y1}^0& m_{y2}^0& \·\·\·& m_{\mathrm{yn}}^0\\ m_{z1}^0& m_{z2}^0& \·\·\·& m_{\mathrm{zn}}^0\end{array}\right\}$

Wherein the raw data measured for i-th time for magnetometer XYZ tri-axle exports;

12) recursive least-squares is utilized to calculate calibration parameter under extraneous magnetic interference and the acting in conjunction of magnetometer sensor error according to ellipsoid fitting formula:

$\left[\begin{array}{c}{m}_x\\ m_y\\ m_z\end{array}\right]=\left[\begin{array}{ccc}\frac{\cos \mathrm{\α}\cos \mathrm{\β}}{k_x}& 0& 0\\ \frac{\cos \mathrm{\α}\sin \mathrm{\β}}{k_x}& \frac{\cos \mathrm{\α}}{k_y}& 0\\ \frac{\sin \mathrm{\γ}}{k_x}& \frac{\sin \mathrm{\α}}{k_y}& \frac{1}{k_z}\end{array}\right]\left[\begin{array}{c}{m}_x^0-m_{\mathrm{bx}}\\ m_y^0-m_{\mathrm{by}}\\ m_z^0-m_{\mathrm{bz}}\end{array}\right]$

$m_x^2+m_y^2+m_z^2=M^2$

Wherein, k _x, k _y, k _zfor the sensitivity error factor, α, beta, gamma is the non-orthogonal error angle of between centers, for the original output of magnetometer, m _bx, m _by, m _bzbe zero inclined error, m _x, m _y, m _zfor magnetometer after preliminary corrections exports, M is for work as geomagnetic field intensity.

After having calibrated, unmanned plane record k _x, k _y, k _z, α, beta, gamma, m _bx, m _by, m _bz9 parameters, by land station's instruction step 2) calculating.

4. calibration steps according to claim 3, is characterized in that, described step 2) be specially:

21) magnetometer sensor coordinate system m is established to depart from the fleet angle φ of unmanned plane body axis system b _x, φ _y, φ _z, suppose φ _x, φ _y, φ _zbe little angle, then alignment error matrix can be expressed as:

$C_b^m=\left[\begin{array}{ccc}1& {\mathrm{\φ}}_z& -{\mathrm{\φ}}_y\\ -{\mathrm{\φ}}_z& 1& {\mathrm{\φ}}_x\\ {\mathrm{\φ}}_y& -{\mathrm{\φ}}_x& 1\end{array}\right]$

22) again Small and micro-satellite is carried out multiposition rotation, according to step 1 around magnetometer XYZ tri-axle respectively) calculate parameters obtained k _x, k _y, k _z, α, beta, gamma, m _bx, m _by, m _bz, the magnetometer after correcting in record rotary course exports:

$M^{\′}=\left\{\begin{array}{cccc}{m}_{x1}& m_{x2}& \·\·\·& m_{\mathrm{xn}}\\ m_{y1}& m_{y2}& \·\·\·& m_{\mathrm{yn}}\\ m_{z1}& m_{z2}& \·\·\·& m_{\mathrm{zn}}\end{array}\right\}$

Wherein m _xi, m _yi, m _zi, (i=1,2,3 ... n) for the data after i-th measurement update of magnetometer XYZ tri-axle export;

23) the attitude data roll angle of Small and micro-satellite is utilized pitching angle theta, course angle ψ, utilize least square method of recursion to calculate to alignment error matrix parameter;

$C_m^b=C_b^{m^T}$

Wherein, m _x, m _y, m _zfor through step 1) correct after magnetometer output, M _x, M _y, M _zfor terrestrial magnetic field component under navigational coordinate system, for sensor alignment error matrix to be measured;

After having calibrated, unmanned plane record φ _x, φ _y, φ _z3 parameters, start step 3 by land station's instruction) calculating.

5. method according to claim 4, is characterized in that, described step 3) to step 1), step 2) calculate the error parameter of gained and carry out conformity calculation, the magnetometer error parameter finally obtaining Small and micro-satellite complete machine is error matrix C _total, zero inclined error M _b.

6. method according to claim 5, is characterized in that, wherein

$C_{\mathrm{total}}=\left[\begin{array}{ccc}1& -{\mathrm{\φ}}_z& {\mathrm{\φ}}_y\\ {\mathrm{\φ}}_z& 1& -{\mathrm{\φ}}_x\\ -{\mathrm{\φ}}_y& {\mathrm{\φ}}_x& 1\end{array}\right]\left[\begin{array}{ccc}\frac{\cos \mathrm{\α}\cos \mathrm{\β}}{k_x}& 0& 0\\ \frac{\cos \mathrm{\α}\sin \mathrm{\β}}{k_x}& \frac{\cos \mathrm{\α}}{k_y}& 0\\ \frac{\sin \mathrm{\γ}}{k_x}& \frac{\sin \mathrm{\α}}{k_y}& \frac{1}{k_z}\end{array}\right]$

$M_b=\left[\begin{array}{c}{m}_{\mathrm{bx}}\\ m_{\mathrm{by}}\\ m_{\mathrm{bz}}\end{array}\right]$

7. method according to claim 6, is characterized in that, the output calibration of magnetometer is

M _cal＝C _total·(M ₀-M _b)

Wherein, M _calfor after complete machine calibration, magnetometer exports, M ₀for the original output of magnetometer.