CN103424780B - Carrier aircraft magnetic environment compensation method based on induction coil - Google Patents

Abstract

The invention discloses a kind of carrier aircraft magnetic environment compensation method based on induction coil, mainly utilize total amount magnetometer difference measurement carrier aircraft magnetic environment stationary magnetic field amount, the magnetometer survey alternating magnetic field data of the logical induction coil of band, set up carrier aircraft magnetic environment AC magnetic field department pattern according to the data obtained, from model, pick out alternating magnetic field model parameter, determine alternating magnetic field amount according to parameters obtained again, finally by stationary magnetic field and the synthetic carrier aircraft magnetic environment total amount that obtains of alternating magnetic field. Because this method is directly measured the alternating magnetic field being caused by carrier aircraft equipment in carrier aircraft magnetic environment, avoid the identification in the lump to earth magnetism and carrier aircraft Induced magnetic field in the compensation method of traditional carrier aircraft magnetic environment, improve Model Distinguish precision; In carrier aircraft magnetic environment, stationary magnetic field part can not change after airborne equipment installs sizing, measures the identification that just can realize this part as long as do on the ground first difference.

Description

Carrier aircraft magnetic environment compensation method based on induction coil

Technical field

The invention belongs to aerial remote reconnaissance field, be specifically related to the carrier aircraft magnetic environment compensation based on induction coilMethod.

Background technology

The magnetic environment of carrier aircraft has important impact to airborne magnetic survey. Carrier aircraft magnetic environment comprises: carrier aircraftInduced field in upper magnetic source magnetic field and carrier aircraft, wherein magnetic source magnetic field comprise as electromagnetic relay,Closing of the magnetic field that permanent-magnet material in ferrite isolator, motor produces and all ferromagnetic materials and theyThe magnetic field, hard magnetic source that gold formation shows after waiting soft magnetic materials to be magnetized; Induced field comprises directlyStream and the steady magnetic field and the alternating magnetic field that exchange wire and loop generation.

The identification problem of carrier aircraft magnetic environment is carrier aircraft magnetic environment compensation in airborne magnetic survey specialty alwaysImportant research problem. Conventionally carrier aircraft magnetic survey subsystem is a subsystem that adds repacking, while adding repackingThe magnetic environment of aircraft cannot re-start magnetic and design. Fixed magnet in carrier aircraft and having magnetizedFerromagnetic material, can cause Magnetic Sensor to produce deviation. On the other hand, the current loop on aircraft, meetingProduce the alternating magnetic field of induction at periphery. Therefore, in order to obtain real earth's magnetic field data, necessaryCarry out the magnetic compensation of carrier aircraft. And to compensate carrier aircraft magnetic environment, just must know aircraft magnetic environmentNot.

The physical quantity that characterizes magnetic power is magnetic moment, is defined as by electric current and this loop of loop and surroundsThe product of area. Unit is ampere. rice²。

In theory, the identification of airborne magnetic environment can be by the actual output of carrier aircraft sensor and reasonOpinion Geomagnetic Field Model (as IGRF model etc.) realize. But, the resolution of existing theoretical model itselfRate is compared when earth's magnetic field with actual with precision, has the error of nT up to a hundred. Therefore can exist and need estimate simultaneouslyMeter carrier aircraft magnetic environment and, be 18 carrier aircraft magnetic field models that proposed in 1961 by Leliak the earliest:

B_T＝c₁cosX+c₂cosY+c₃cosZ+H₀(c₄cos²X+c₅cosXcosY+

+c₆cosXcosZ+c₇cos²Y+c₈cosYcosZ+c₉cos²Z)+

+H₀(c₁₀cosX(cosX)′+c₁₁cosX(cosY)′+c₁₂cosX(cosZ)′+(1)

+c₁₃cosY(cosX)′+c₁₄cosY(cosY)′+c₁₅cosY(cosZ)′+

c₁₆cosZ(cosX)′+c₁₇cosZ(cosY)′+c₁₈cosZ(cosZ)′)

The carrier aircraft magnetic field model of improved Leliak also can be expressed as

B_T＝H₀+H_p+H_i+H_e+H_d(2)

Wherein H₀For earth's magnetic field, H_pFor constant magnetic sensing, H_iFor induced field, H_eEddy current magnetism,H_dFor the high frequency magnetic field of electrical installation generation. Four magnetic environments that form carrier aircraft induction next.

$B_T=H_0\left(\begin{array}{c}\cos X\\ \cos Y\\ \cos Z\end{array}\right)+\left(\begin{array}{c}{H}_{px}\\ H_{py}\\ H_{pz}\end{array}\right)+{\left(\begin{array}{c}\cos X\\ \cos Y\\ \cos Z\end{array}\right)}^T\left\{K\left(\begin{array}{c}\cos X\\ \cos Y\\ \cos Z\end{array}\right)+L{\left(\begin{array}{c}\cos X\\ \cos Y\\ \cos Z\end{array}\right)}^{\′}\right\}{H}_0+{H_0}^{\′}L\left(\begin{array}{c}\cos X\\ \cos Y\\ \cos Z\end{array}\right)+H_d---\left(3\right)$

X in formula, Y, the Z projected angle on axially that is earth's magnetic field three of carrier aircrafts, K is induction matrix,L is eddy current matrix coefficient. As can be seen from the above equation in the composition of carrier aircraft total magnetic field, body stationary magnetic fieldBe constant, earth's magnetic field day become factor and also can be approximately at short notice constant magnetic field, and induced magnetismField is relevant to carrier aircraft attitude with eddy current magnetism, and can think steadily to make an uproar in the magnetic field that electrical installation producesSound. The compensation in aircraft magnetic field is exactly to utilize the magnetic field data of measuring to estimate unknowm coefficient above, justCan from the resultant field of built in measurement, deduct carrier aircraft induced magnetic field, finally obtain the earth's magnetic field of accurately revisingData.

Owing to having very strong correlation between 18 coefficients in above formula, and be difficult to measure whole spaceThe magnetic field data of traversal. Therefore be difficult to accurately estimate these coefficients by conventional method.

Summary of the invention

The deficiency existing for prior art, the object of the present invention is to provide a kind of based on induction coilThe compensation method of carrier aircraft magnetic environment. The present invention is according to the frequency spy of each part in carrier aircraft magnetic field environmentPoint, and the feature of different principle magnetometer employing identification stage by stage, reduce identification difficulty and guarantee simultaneouslyThe precision of identification.

For realizing goal of the invention of the present invention, adopt following technical scheme:

Carrier aircraft magnetic environment compensation method based on induction coil, comprises the steps:

(a) set up carrier aircraft magnetic environment model, and decompose;

(b) utilize optically pumped magnetometer and bandpass filter to measure carrier aircraft magnetic environment resultant field;

(c) utilize total to (b) step of the logical triaxial induction coil type magnetometer of band and sef-adapting filterThe compensation of alternating magnetic field undulate quantity is carried out in field;

(d) utilize the measured value of three axis fluxgates and bandpass filter to estimate the direct current of carrier aircraft magnetic environmentThe model parameter of component;

(e) utilize in-flight the result of calculation of (d) step further to compensate the compensation result of (c).

Described step (a) is set up induced field and the eddy current magnetism in carrier aircraft magnetic environment AC magnetic field modelBelong to intermediate frequency alternating magnetic field, according to Differential Principle induced field H_iWith eddy current magnetism H_eBe decomposed into and working asA undulate quantity Δ H superposes on fixed value basis under front attitude condition_c。

Triaxial induction coil type magnetometer in described step (c) has been selected with logical induction coil, usesThe undulate quantity of the high frequency component in filtering carrier aircraft magnetic environment is measured. Thereby can in the compensation of carrier aircraft magnetic environmentTo avoid the identification compensation to high frequency component in prior art, use step (d) and step (c)Result directly compensates and obtains target geomagnetic field intensity step (b).

In wherein said step (b) the total field measurement of carrier aircraft magnetic environment and step (c) carrier aircraft magnetic environment, hand overThe measurement of varying magnetic field undulate quantity is online adaptive compensation, step (d) carrier aircraft magnetic environment direct current compositional modelComplete identification on ground, for carrier aircraft in line computation. Thereby also having realized whole carrier aircraft magnetic environment mendsThe adaptivity of repaying.

In described (c) step, triaxial induction coil type magnetometer measures undulate quantity to variation magnetic fieldΔH_a＝ΔH_ia+ΔH_ea, wherein Δ H_iaInduced field H_iUndulate quantity, Δ H_eaEddy current magnetism H_eRippleMomentum, and then the resultant field that optically pumped magnetometer is measured first carries out Δ H_aAdaptive equalization; Described Δ H_aFromAdaptive compensation has adopted sef-adapting filter to realize the optimum filtering to signal, and sef-adapting filter is logicalThe variation of crossing adaptive algorithm tracking signal regulates the coefficient of wave filter automatically.

Because the inventive method is directly measured the alternating magnetic field being caused by carrier aircraft equipment in carrier aircraft magnetic environment,Avoid the identification in the lump to earth magnetism and carrier aircraft Induced magnetic field in the compensation method of traditional carrier aircraft magnetic environment, carriedHigh Model Distinguish precision; In carrier aircraft magnetic environment, direct current component magnetic field part installs at airborne equipmentAfter sizing, can not change, just can realize distinguishing of this part as long as do on the ground first difference measurementKnow.

Brief description of the drawings

Fig. 1 is carrier aircraft magnetic environment compensation process flow chart of the present invention;

Fig. 2 is carrier aircraft magnetic environment AC magnetic field component undulate quantity adaptive equalization schematic diagram of the present invention.

Detailed description of the invention

How further illustrate the present invention below in conjunction with accompanying drawing 1 and Fig. 2 realizes.

Embodiment

By in the forming of carrier aircraft total magnetic field in (3) formula, body stationary magnetic field itself is changeless,Earth's magnetic field day become factor and also can be considered at short notice the DC component in composition, induced field and eddy currentMagnetic field be its frequency relevant to carrier aircraft attitude in medium and low frequency band, and electrical installation produce magnetic field placeIn high-band frequency range. According to (3) formula known in the time that carrier aircraft is done linear uniform motion because carrier aircraft attitudeAngle X, Y, Z fixes, induced field H_iWith eddy current magnetism H_eConstant, each component when carrier aircraft is done the motion of automobileMagnetic field all can exist, and can think induced field H from Differential Principle_iWith eddy current magnetism H_eCan be in current perseveranceA undulate quantity Δ H superposes in the basis of valuation_c。

High sensitivity triaxial induction coil type magnetometer based on electromagnetic induction principle can detect in real time and carryFaint variation delta H in machine_a, but cannot detect the DC component magnetic field in component. In componentDC component magnetic field H_p, induction matrix COEFFICIENT K and eddy current matrix coefficient L can enter on the ground in advanceRow picks out.

Having provided magnetic compensation computational process as shown in Figure 1 according to above-mentioned principle the present invention repaiies for obtainingEarth's magnetic field data just, the process of magnetic compensation shown in Fig. 1 is divided into and exchanges the compensation of variable compensated and DC componentTwo parts, exchange variable compensated link and have adopted a sef-adapting filter FIR filter model to be used forCarrier aircraft online adaptive compensation in-flight, DC component compensation tache can be distinguished in earth base measurementKnow, thereby realize the adaptive process of whole carrier aircraft magnetic compensation process. For H in (3) formula_dHeightFrequently disturb, after all sensor measurement links, all connect a bandpass filter, in all measurementsIn data, remove H_dImpact, be follow-up different sensors different phase measurement data uniform based.

(1) carrier aircraft total magnetic field DC component ground identification

Shown in total magnetic field, ground direct current component recognition module, according to (3) formula, carrier aircraft lures as shown in Figure 1Magnetic conduction environment direct current component is by H_c＝H_p+H_ic+H_ec。

Kill engine and machine on after all electronic equipments and power supply, in three attitude frees degree of carrier aircraftSampling respectively: carrier aircraft is stopped on the ground with different course angles, the angle of pitch, inclination angle, in each operating modeUnder, measure total magnetic field three-component (B aboard with identical measurement coordinate system_Tx,B_Ty,B_Tz)_iWith nearThree-component (the H in earth's magnetic field_0x,H_0y,H_0z)_i, then according to measurement to earth's magnetic field three-component can calculate groundMagnetic field is at the projected angle (X, Y, Z) of measuring under coordinate system measurement_i. (B_Tx,B_Ty,B_Tz)_i、(H_0x,H_0y,H_0z)_i、(X,Y,Z)_i(3) formula of high frequency item has been ignored in substitution.

$B_T=H_0\left(\begin{array}{c}\cos X\\ \cos Y\\ \cos Z\end{array}\right)+\left(\begin{array}{c}{H}_{px}\\ H_{py}\\ H_{pz}\end{array}\right)+{\left(\begin{array}{c}\cos X\\ \cos Y\\ \cos Z\end{array}\right)}^T\{K\left(\begin{array}{c}\cos X\\ \cos Y\\ \cos Z\end{array}\right)+L{\left(\begin{array}{c}\cos X\\ \cos Y\\ \cos Z\end{array}\right)}^{\′}\}{H}_0---\left(4\right)$

$B_T=\left(\begin{array}{c}{H}_{px}\\ H_{py}\\ H_{pz}\\ k_{xx}-k_{zz}\\ k_{xy}+k_{yx}\\ ......\\ l_{xx}-l_{zz}\\ ......\end{array}\right)\left(\begin{array}{c}\cos X\\ \cos Y\\ \cos Z\\ {\cos }^{2}X\\ \cos X\cos Y\\ ......\\ \cos X{\cos }^{\′}X\\ ......\end{array}\right)+H_0+H_p---\left(5\right)$

Adopt classical least-squares estimation just can estimate the DC component magnetic field H in above formula_p, inductionMatrix coefficient K and eddy current matrix coefficient L.

(2) carrier aircraft alternating magnetic field undulate quantity Δ H_aOnline adaptive compensation.

As Fig. 1 total magnetic field exchanges as shown in component undulate quantity adaptive equalization module, through bandpass filterFiltering high frequency magnetic field, relies on triaxial induction coil to arrive undulate quantity to the high-sensitivity measurement of variation magnetic fieldΔH_a＝ΔH_ia+ΔH_ea, and then the resultant field that optically pumped magnetometer is measured first carries out Δ H_aAdaptive equalization.Adaptive equalization principle process as shown in Figure 2, DC component that what optically pumped magnetometer measured is with exchangeThe summation of component, and the magnetometer survey of triaxial induction coil type is to undulate quantity Δ H_a, adaptive in order to realizeThe undulate quantity compensation of answering, has adopted sef-adapting filter (adaptivefilter) to realize to signalGood filtering, sef-adapting filter regulates wave filter automatically by the variation of adaptive algorithm tracking signalCoefficient. Because it has very strong adaptability and superior filtering performance in online signal process fieldObtain extensive use.

The visual noise transducer 2 of doing in Fig. 2 of triaxial induction coil type magnetometer, its outputx(k)＝|ΔH_a(k) | after the adjustable digital filter of parameter, delivering to Canceller, with sensingOutput signal y (the k)=B of device 1 optically pumped magnetometer_T(k) subtract each other, just can mend the noise measuringRepay. The object that noise transducer 2 inserts wave filter is exactly to want the transmission of comfort noise source to two sensorProperty difference, and the inconsistency of balanced two sensor characteristics, so that the output of wave filter is forced as far as possibleThe induced noise of nearly sensor 1. In figure, sef-adapting filter has used the adjustable FIR digital filtering of parameterDevice, the time independent variable of each variable all represents with sampling sequence k.

Sef-adapting filter adopts FIR transversal filter to estimate carrier aircraft noise circumstance model

$z\left(k\right)=\underset{m=1}{\overset{M}{\Σ}}{h}_m\left(k\right)x(k-m+1)$

Wherein χ is noise signal, and adaptive algorithm is for adjusting the weighting system of auto-adaptive fir filterNumber vector h (k), the computational process of parameters adaption algorithm is as follows:

1) at moment k, the output z (k) of calculating filter

2) calculate e (k)=y (k)-z (k), wherein y (k) is magnetic field total amount signal.

3) make the mean-square value of the output e (k) of Canceller according to minimum mean square error criterion (LMS)E[e²(k)] reach minimum principle, calculate filter parameter next time;

4) k=k+1, jumps to step 1);

According to the mean-square value E[e of output e (k)²(k)] reach minimum principle, have following relation

E[e²(k)]＝E[(s(k)+n(k)-z(k))²]

＝E[s²(k)]+E[(n(k)-z(k))²]+2E[n(k)s(k)]-2E[z(k)s(k)](6)

Because the interference noise n (k) of carrier aircraft is uncorrelated mutually with measured signal s (k), the output of sensor 2X (k) is also uncorrelated mutually with s (k), thereby has

E[n(k)s(k)]＝0

E[z(k)s(k)]＝0

E[e²(k)]＝E[s²(k)]+E[(n(k)-z(k))²](7)

Wherein E[s²(k) be] mean power of a stationary signal, so work as E[e²(k) it is minimum that value] reachesTime, also just make z (k) be tending towards n (k), realize the Adaptive Identification of noise model.

FIR filter parameter h (k) can calculate as follows, E[e²(k)] index reaches hour, can be from totalRemove any part relevant to x (k) in magnetic-field measurement signal y (k), remaining e (k) is reservation and phase not onlyThe part of closing, namely wishes

E[e(k)x(k-m)]＝00≤m≤M-1(8)

Wave filter is exported to substitution above formula, and being write as vector form can obtain

E[e(k)X(k)]＝E[(y(k)-h^T(k)X(k))X(k)]＝0(9)

E[(X(k)y(k)]＝E[X(k)X^T(k)]h(k)(10)

Be designated as R_xy＝R_xxH (k), works as R_xxWhen full rank there is unique solution in weight coefficient h, obtains

$h\left(k\right)=R_{xx}^{-1}{R}_{xy}---\left(11\right)$

(3) carrier aircraft induction magnetic ambient compensation calculates

Exchange the compensation of component undulate quantity adaptive equalization module through total magnetic field, the e (k) of output disappearsExcept wave variable Δ H_aCarrier aircraft total magnetic field, its content only includes carrier aircraft induction magnetic environment direct current componentH_c＝H_p+H_ic+H_ecWith earth's magnetic field H₀. Thereby e (k) is by total magnetic field, Canceller cancellation ground direct current componentThe direct current component H that recognition module identifies_c, can obtain final real-time target earth's magnetic field data.

Claims (6)

1. the carrier aircraft magnetic environment compensation method based on induction coil, comprises the steps:

(a) set up carrier aircraft magnetic environment model, and decompose;

(b) utilize optically pumped magnetometer and bandpass filter to measure carrier aircraft magnetic environment resultant field;

(c) utilize triaxial induction coil type magnetometer and sef-adapting filter to enter the resultant field of (b) stepThe compensation of row alternating magnetic field undulate quantity;

(d) utilize the measured value of three axis fluxgates and bandpass filter to estimate the direct current of carrier aircraft magnetic environmentThe model parameter of component;

(e) utilize in-flight the result of calculation of (d) step further to compensate the compensation result of (c).

2. the carrier aircraft magnetic environment compensation method based on induction coil according to claim 1, its spyLevy and be, described step (a) is set up in carrier aircraft magnetic environment model, the induced field of AC magnetic field modelBelong to intermediate frequency alternating magnetic field with eddy current magnetism, according to Differential Principle induced field H_iWith eddy current magnetism H_eBe decomposed into the undulate quantity Δ H that superposes on the fixed value basis under current attitude condition_c。

3. the carrier aircraft magnetic environment compensation method based on induction coil according to claim 1, its featureBe, the triaxial induction coil type magnetometer in described step (c) has been selected with logical induction coil,The undulate quantity that is used for the high frequency component that filters carrier aircraft magnetic environment is measured.

4. the carrier aircraft magnetic environment compensation method based on induction coil according to claim 1, its spyLevy and be, wherein said step (b) the total field measurement of carrier aircraft magnetic environment and step (c) carrier aircraft magnetic environmentThe measurement of middle alternating magnetic field undulate quantity is online adaptive compensation, step (d) carrier aircraft magnetic environment direct current componentModel completes identification on ground, for carrier aircraft in line computation.

5. the carrier aircraft magnetic environment compensation method based on induction coil according to claim 1, its spyLevy and be, in described (c) step, triaxial induction coil type magnetometer measures undulate quantity to variation magnetic fieldΔH_a＝ΔH_ia+ΔH_ea, and then the resultant field that optically pumped magnetometer is measured first carries out Δ H_aAdaptive equalization,Wherein Δ H_iaInduced field H_iUndulate quantity, Δ H_eaEddy current magnetism H_eUndulate quantity.

6. the carrier aircraft magnetic environment compensation method based on induction coil according to claim 5, its spyLevy and be, described Δ H_aAdaptive equalization has adopted sef-adapting filter to realize the best filter to signalRipple, sef-adapting filter regulates the coefficient of wave filter automatically by the variation of adaptive algorithm tracking signal.