CN102393201B - Dynamic lever arm compensating method of position and posture measuring system (POS) for aerial remote sensing - Google Patents

Abstract

The invention provides a dynamic lever arm compensating method of a position and posture measuring system (POS) for aerial remote sensing. The method comprises the following steps of: to solve the problem of real-time variation of the lever arm between a measuring center of an inertia measuring unit (IMU) and phase center of a GPS (Global Positioning System) antenna due to rotation of a three-axis inertia stabilizing platform frame, obtaining an actual lever arm between the IMU measuring center and the phase center of the GPS antenna through calculating a dynamic lever arm between the center of the three-axis inertia stabilizing platform and the IMU measuring center in real time; and figuring out angular velocity of an initial coordinate system of the three-axis inertia stabilizing platform under the initial coordinate system of the three-axis inertia stabilizing platform relative to a local geographic coordinate system so as to compensate the dynamic lever arm. The dynamic lever arm compensating method provided by the invention has the characteristics of high accuracy, simplicity in operation and easiness for realization; the problem that the POS lever arm is hard to be accurately compensated while the three-axis inertia stabilizing platform is adopted for aerial remote sensing is solved; and the accuracies of POS and aerial remote sensing imaging load are improved.

Description

Airborne remote sensing position and orientation measurement system (POS) dynamic lever arm compensating method

Technical field

The present invention relates to a kind of airborne remote sensing with position and orientation measurement system (POS) dynamic lever arm compensating method, belong to the airborne remote sensing field, be applied to adopt the airborne remote sensing of three axle inertially stabilized platforms, improved the precision of POS and airborne remote sensing imaging load.

Background technology

Airborne remote sensing is a kind of take aircraft as carrier, utilizes remote sensing load to obtain the hi-tech of the various spatial geographic informations of earth surface.Require load to do the at the uniform velocity ideal movements of straight line in the space when airborne remote sensing system carries out high-resolution imaging, but aircraft unavoidably can be subject to the impact of the external disturbances such as fitful wind, turbulent flow, makes load depart from the ideal movements track, cause the load image quality to descend.Therefore, realize the high precision imaging of airborne remote sensing system, must isolate and motion compensation the flight disturbance.Three axle inertially stabilized platforms are held in as load level and point to the aircraft flight direction by three frameworks of servocontrol, thereby being isolated to a certain extent the external disturbance in flight course by three system frameworks.Because three axle inertially stabilized platform loads are large, conduct oneself with dignity little, response speed is limited, the flight disturbance can not be isolated fully, therefore, must use POS accurately to measure the flight disturbance of failing to isolate, obtain the kinematic parameters such as position, speed and attitude of imaging load phase center, and carry out motion compensation in imaging process.

POS is comprised of IMU, GPS receiver, POS navigational computer (PCS) and the poster processing soft etc.Wherein IMU is used for measuring three dimensional angular speed and the three-dimensional line acceleration that connects firmly carrier with it, resolve through strap-down inertial, can obtain position, speed and the attitude information of carrier, have that precision is high in short-term, the advantages such as output is continuous and fully autonomous, but its navigation error accumulates in time.GPS can provide high-precision position and velocity information for a long time, but exports discontinuously, and attitude information can not be provided, and gps signal can not be realized the location when being subject to blocking.POS utilizes inertial navigation and the natural complementarity of GPS navigation, the application message integration technology, the moment of inertia measurement information is merged with the GPS measurement information, can obtain continuously, in real time the comprehensive kinematic parameter such as position, speed and attitude of carrier, and accumulation in time of error.

When the GPS measurement information merges with the moment of inertia measurement information, must carry out the lever arm compensation.Because gps antenna can not be installed together with IMU, in order to receive gps satellite signal, gps antenna generally is arranged on the aircraft top, IMU is arranged on engine room inside, distance between the two is generally all more than 1 meter, but the positional precision of GPS and velocity accuracy can reach respectively 0.05m and 0.005m/s, and the position that therefore GPS must be obtained and velocity information measure lever arm between center and gps antenna phase center by IMU and compensate to IMU measurement center.But in flight course, inertially stabilized platform can be rotated three frameworks in real time to be held in as load level and to point to the aircraft flight direction, thereby the relative orientation that causes IMU to measure between center and gps antenna phase center constantly changes, and makes the lever arm real-time change between IMU measurement center and gps antenna phase center.Do not have relative orientation to change between traditional lever arm compensating method hypothesis IMU and gps antenna, namely the lever arm that measures between center and gps antenna phase center of IMU is invariable, utilizes strap inertial navigation algorithm to resolve to obtain

Battle array, With lever arm measured value l ^bCarry out the lever arm compensation.Therefore, traditional lever arm compensating method is applied to adopt the airborne remote sensing of three axle inertially stabilized platforms can produce very large error even can not to use.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, propose a kind of airborne remote sensing POS dynamic lever arm compensating method.The method is rotated for three axle inertially stabilized platform frameworks and is caused IMU to measure the problem of the lever arm real-time change between center and gps antenna phase center, by the dynamic lever arm between real-time calculating three axle inertially stabilized platform centers and IMU measurement center, obtain the actual lever arm between IMU measurement center and gps antenna phase center, and calculate in real time the three relatively local geographic coordinates of axle inertially stabilized platform initial coordinate systems and tie up to the three lower angular velocity of axle inertially stabilized platform initial coordinate system, carry out dynamic lever arm and compensate.The present invention has the advantages that precision is high, simple to operate, be easy to realize, when having solved airborne remote sensing use three axle inertially stabilized platform, the POS lever arm is difficult to the problem of fine compensation, has improved the precision of POS and airborne remote sensing imaging load.

Technical solution of the present invention is: a kind of airborne remote sensing POS dynamic lever arm compensating method, and concrete steps are as follows:

(1) under three axle inertially stabilized platform initial coordinate are, measure respectively the lever arm between three axle inertially stabilized platform centers and gps antenna phase center

And three lever arm between axle inertially stabilized platform center and Inertial Measurement Unit (IMU) measurement center

(2) calculate the Direct cosine matrix that the gps data moment three axle inertially stabilized platform initial coordinate are tied to local geographic coordinate system;

(3) Direct cosine matrix that utilizes lever arm that step (1) obtains and step (2) to obtain, calculate gps data constantly IMU measure dynamic lever arm between center and gps antenna phase center;

(4) Direct cosine matrix that utilizes step (2) to obtain calculates the three relatively local geographic coordinates of axle inertially stabilized platform initial coordinate system and ties up to angular velocity under three axle inertially stabilized platform initial coordinate systems;

(5) angular velocity that the dynamic lever arm that the Direct cosine matrix that obtains based on step (2), step (3) obtain and step (4) obtain, GPS position data and speed data are carried out the dynamic lever arm compensation, and the gps data after compensating and inertial data merge, and obtains optimum kinematic parameter;

(6) repeating step (2) is to step (5), until the processing of POS system data finishes.

Principle of the present invention: rotate the problem that causes the lever arm real-time change between IMU measurement center and gps antenna phase center for three axle inertially stabilized platform frameworks, the present invention is under three axle inertially stabilized platform initial coordinate are, the dynamic lever arm l that IMU is measured between center and gps antenna phase center is decomposed into the poor of two lever arms, as shown in Figure of description 2, calculate lever arm l ₁With lever arm l ₂Poor, can obtain dynamic lever arm l.Its Caused by Lever Arm l ₁Be the lever arm between three axle inertially stabilized platform centers and gps antenna phase center, lever arm l ₂It is the dynamic lever arm between three axle inertially stabilized platform centers and IMU measurement center.By comparative illustration book accompanying drawing 2a and Figure of description 2b as can be known, l ₁Be fixing lever arm, the framework along with inertially stabilized platform rotates and changes; l ₂Be dynamic lever arm, along with the framework of inertially stabilized platform rotates and changes.By measuring the fixedly lever arm l between three axle inertially stabilized platform centers and gps antenna phase center ₁, and calculate in real time dynamic lever arm l between three axle inertially stabilized platform centers and IMU measurement center ₂Thereby, can accurately obtain because three axle inertially stabilized platform frameworks rotate the lever arm l that the IMU that causes measures real-time change between center and gps antenna phase center, recycling strap inertial navigation algorithm and three axle inertially stabilized platform three axle rotation relations calculate

Battle array,

With lever arm calculated value l ^b' carry out real-time dynamic lever arm to compensate.

The present invention's advantage compared with prior art is: the present invention is by calculating in real time the dynamic lever arm l between IMU measurement center and gps antenna phase center ^b' and

Carry out accurate dynamic lever arm compensation, prior art has the high characteristics of precision relatively, and when having solved airborne remote sensing use three axle inertially stabilized platform, the POS lever arm is difficult to the problem of fine compensation, has improved the precision of POS and airborne remote sensing imaging load.

Description of drawings

Fig. 1 is POS dynamic lever arm compensating method process flow diagram of the present invention;

Fig. 2 is each subsystem relative orientation schematic diagram of airborne remote sensing of the present invention, in figure, and ox _b′y _b′z _b′Coordinate is that three axle inertially stabilized platform initial coordinate are, ox _by _bz _bCoordinate is three axle inertially stabilized platform inner frame coordinate systems, O _PBe three axle inertially stabilized platform centers, O _IFor IMU measures center, O _GBe the gps antenna phase center.Wherein, Fig. 2 a is three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bWith three axle inertially stabilized platform initial coordinate be ox _b′y _b′z _b′Relative orientation schematic diagram during coincidence; Fig. 2 b is three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bWith three axle inertially stabilized platform initial coordinate be ox _b′y _b′z _b′Relative orientation schematic diagram when not overlapping.

Embodiment

As shown in Figure of description 1, concrete enforcement of the present invention comprises the following steps:

1, three axle inertially stabilized platforms are set to the leveling pattern, three axle inertially stabilized platforms are controlled three axle frameworks, make the photoelectric coder of inertially stabilized platform three axles be output as zero, establishing at this moment, three axle inertially stabilized platform inner frame coordinates are that three axle inertially stabilized platform initial coordinate are ox _b′y _b′z _b′, with b ' expression; If the inner frame coordinate system ox that three axle inertially stabilized platforms are real-time _by _bz _bRepresent with b; If local geographic coordinate system ox _ny _nz _nRepresent with n.Be ox in three axle inertially stabilized platform initial coordinate _b′y _b′z _b′Under, use transit survey three axle inertially stabilized platform center O _PWith gps antenna phase center O _GBetween lever arm and three axle inertially stabilized platform center O _PAnd O between IMU measurement center _ILever arm, obtain three axle inertially stabilized platform center O _PWith gps antenna phase center O _GBetween lever arm be

Three axle inertially stabilized platform center O _PMeasure center O with IMU _IBetween lever arm be

Then three axle inertially stabilized platforms are set to remote control mode, follow the tracks of POS output, control in real time.Position relation between imaging load, three axle inertially stabilized platforms and IMU is seen Figure of description 2, wherein three axle inertially stabilized platforms are arranged on airframe, imaging load is arranged on three axle inertially stabilized platforms, connect firmly with the inner frame of three axle inertially stabilized platforms, IMU connects firmly with imaging load, measures the real-time kinematic parameter of imaging load.

2, calculate the Direct cosine matrix that the gps data moment three axle inertially stabilized platform initial coordinate are tied to local geographic coordinate system

(1) calculating the gps data moment three axle inertially stabilized platform initial coordinate is ox _b′y _b′z _b′To three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bDirect cosine matrix

Because the housing of three axle inertially stabilized platforms is the roll frame, center is the pitching frame, and inside casing is the course frame, therefore can get

$C_{b^{\′}}^b=\left[\begin{array}{ccc}\cos \left({\mathrm{\ψ}}_1\right)& \sin \left({\mathrm{\ψ}}_1\right)& 0\\ -\sin \left({\mathrm{\ψ}}_1\right)& \cos \left({\mathrm{\ψ}}_1\right)& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{ccc}1& 0& 0\\ 0& \cos \left({\mathrm{\θ}}_1\right)& \sin \left({\mathrm{\θ}}_1\right)\\ 0& -\sin \left({\mathrm{\θ}}_1\right)& \cos \left({\mathrm{\θ}}_1\right)\end{array}\right]\left[\begin{array}{ccc}\cos \left({\mathrm{\γ}}_1\right)& 0& -\sin \left({\mathrm{\γ}}_1\right)\\ 0& 1& 0\\ \sin \left({\mathrm{\γ}}_1\right)& 0& \cos \left({\mathrm{\γ}}_1\right)\end{array}\right]$

Wherein, γ ₁The angle is that the gps data moment three axle inertially stabilized platform housings are with respect to the angle of the initial housing rotation of inertially stabilized platform, θ ₁The angle is that the gps data moment three axle inertially stabilized platform centers are with respect to the angle of the three initial centers rotations of axle inertially stabilized platform, ψ ₁The angle is that the gps data moment three axle inertially stabilized platform inside casings are with respect to the angle of the three initial inside casings rotations of axle inertially stabilized platform.

Because three axle inertially stabilized platforms and GPS have independently clock system separately, photoelectric coder data and the gps data of three axle inertially stabilized platform outputs are difficult to Complete Synchronization, and the photoelectric coder data that are located at gps data inertially stabilized platform three axles that before the moment, sampling obtains are respectively

With

Gps data constantly the photoelectric coder data of inertially stabilized platform three axles that obtain of post-sampling be respectively

With Because each framework inertia of three axle inertially stabilized platforms is all larger, can suppose that three axle inertially stabilized platform frame corners speed are constant under each sampling interval, can get

$\left[\begin{array}{c}{\mathrm{\γ}}_1\\ {\mathrm{\θ}}_1\\ {\mathrm{\ψ}}_1\end{array}\right]=\left[\begin{array}{c}(P_{\mathrm{Ay}}^{+}-P_{\mathrm{Ay}}^{-})(T_{\mathrm{GPS}}-T_A^{-})/(T_A^{+}-T_A^{-})+P_{\mathrm{Ay}}^{-}\\ (P_{\mathrm{Ax}}^{+}-P_{\mathrm{Ax}}^{-})(T_{\mathrm{GPS}}-T_A^{-})/(T_A^{+}-T_A^{-})+P_{\mathrm{Ax}}^{-}\\ (P_{\mathrm{Az}}^{+}-P_{\mathrm{Az}}^{-})(T_{\mathrm{GPS}}-T_A^{-})/(T_A^{+}-T_A^{-})+P_{\mathrm{Az}}^{-}\end{array}\right]$

Wherein, T _GPSBe the gps data UTC time constantly,

For

With

The data sampling UTC time constantly,

For

With

The data sampling UTC time constantly.

(2) calculate gps data three axle inertially stabilized platform inner frame coordinate system ox constantly _by _bz _bTo local geographic coordinate system ox _ny _nz _nDirect cosine matrix

$C_b^n=\left[\begin{array}{ccc}\cos {\mathrm{\γ}}_2\cos {\mathrm{\ψ}}_2+\sin {\mathrm{\γ}}_2\sin {\mathrm{\θ}}_2\sin {\mathrm{\ψ}}_2& \cos {\mathrm{\θ}}_2\sin {\mathrm{\ψ}}_2& \sin {\mathrm{\γ}}_2\cos {\mathrm{\ψ}}_2-\cos {\mathrm{\γ}}_2\sin {\mathrm{\θ}}_2\sin {\mathrm{\ψ}}_2\\ -\cos {\mathrm{\γ}}_2\sin {\mathrm{\ψ}}_2+\sin {\mathrm{\γ}}_2\sin {\mathrm{\θ}}_2\cos {\mathrm{\ψ}}_2& \cos {\mathrm{\θ}}_2\cos {\mathrm{\ψ}}_2& -\sin {\mathrm{\γ}}_2\sin {\mathrm{\ψ}}_2-\cos {\mathrm{\γ}}_2\sin {\mathrm{\θ}}_2\cos {\mathrm{\ψ}}_2\\ -\sin {\mathrm{\γ}}_2\cos {\mathrm{\θ}}_2& \sin {\mathrm{\θ}}_2& \cos {\mathrm{\γ}}_2\cos {\mathrm{\θ}}_2\end{array}\right]$

Wherein, γ ₂, θ ₂, ψ ₂Respectively three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bRelatively local geographic coordinate system ox _ny _nz _nRoll angle, the angle of pitch and course angle.

(3) can further be tried to achieve by above-mentioned analysis: gps data three axle inertially stabilized platform initial coordinate constantly is ox _b′y _b′z _b′To local geographic coordinate system ox _ny _nz _nDirect cosine matrix Can be by the gps data moment three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bTo local geographic coordinate system ox _ny _nz _nDirect cosine matrix With gps data constantly three axle inertially stabilized platform initial coordinate be ox _b′y _b′z _b′To three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bDirect cosine matrix

Dot product obtains, namely $C_{b^{\′}}^n=C_b^n{C}_{b^{\′}}^b$

3, calculating gps data moment IMU measures the dynamic lever arm l between center and gps antenna phase center ^b'

(1) calculate gps data three axle inertially stabilized platform center O constantly _PWith gps antenna phase center O _GBetween lever arm

Be ox in three axle inertially stabilized platform initial coordinate _b′y _b′z _b′Under, inertially stabilized platform in controlling three axle framework rotation processes, three axle inertially stabilized platform center O _PAnd do not have relative orientation to change between aircraft, therefore three axle inertially stabilized platform center O _PWith gps antenna phase center O _GBetween the relative orientation relation constant, the three axle inertially stabilized platform center O that obtained by step 1 _PWith gps antenna phase center O _GBetween lever arm With Equate, namely

$l_1^{b^{\′}}=l_{01}^{b^{\′}}$

(2) calculate gps data three axle inertially stabilized platform center O constantly _PMeasure center O with IMU _IBetween lever arm

Because the three real-time control frameworks of axle inertially stabilized platform rotate to be held in as load level and point to the aircraft flight direction, make

Real-time change, but because IMU and three axle inertially stabilized platform inner frames connect firmly, so IMU measures center O _IAt three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bPosition coordinates and IMU to measure the center be ox in three axle inertially stabilized platform initial coordinate _b′y _b′z _b′Position coordinates identical, can get

$l_2^b=l_{02}^{b^{\′}}$

Be ox by the gps data moment three axle inertially stabilized platform initial coordinate that obtain in step 2 _b′y _b′z _b′To three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bDirect cosine matrix Can get gps data three axle inertially stabilized platform inner frame coordinate system ox constantly by transposition _by _bz _bBe ox to three axle inertially stabilized platform initial coordinate _b′y _b′z _b′Direct cosine matrix

$C_b^{b^{\′}}=C_{b^{\′}}^{\mathrm{bT}}$

Thereby can get gps data three axle inertially stabilized platform center O constantly _PMeasure center O with IMU _IBetween lever arm

$l_2^{b^{\′}}=C_b^{b^{\′}}{l}_2^b$

(3) can further be tried to achieve by above-mentioned analysis: gps data IMU constantly measures center O _IWith gps antenna phase center O _GBetween dynamic lever arm l ^b' can be by the gps data moment three axle inertially stabilized platform center O _PWith gps antenna phase center O _GBetween lever arm

With the gps data moment three axle inertially stabilized platform center O _PMeasure center O with IMU _IBetween lever arm

Difference obtain, namely

$l^{b^{\′}}=l_1^{b^{\′}}-l_2^{b^{\′}}$

4, calculate the three relatively local geographic coordinates of axle inertially stabilized platform initial coordinate system and tie up to angular velocity under three axle inertially stabilized platform initial coordinate systems

(1) calculate three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bRelative three axle inertially stabilized platform initial coordinate are ox _b′y _b′z _b′At three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bUnder angular velocity

By step 2 as can be known, the photoelectric coder data of gps data inertially stabilized platform three axles that before the moment, sampling obtains are respectively

The photoelectric coder data of inertially stabilized platform three axles that gps data moment post-sampling obtains are respectively

With

The photoelectric coder data cycle of three axle inertially stabilized platform outputs is 0.01 second.Because each framework inertia of three axle inertially stabilized platforms is larger, can suppose between adjacent two sampling instants, three axle inertially stabilized platform frame corners speed are constant, can get three frame corners speed and be:

$w_{b^{\′}b}^b=\left[\begin{array}{c}{w}_x\\ w_y\\ w_z\end{array}\right]=\left[\begin{array}{c}(P_{\mathrm{Ax}}^{+}-P_{\mathrm{Ax}}^{-})/0.01\\ (P_{\mathrm{Ay}}^{+}-P_{\mathrm{Ay}}^{-})/0.01\\ (P_{\mathrm{Az}}^{+}-P_{\mathrm{Az}}^{-})/0.01\end{array}\right]$

When the photoelectric coder data noise of three axle inertially stabilized platforms outputs is larger, need first the photoelectric coder data to be carried out filtering, then adopt the method for interpolation to obtain the inertially stabilized platform three time dependent functions of axis angular position, obtain the angular velocity of inertially stabilized platform three axles by constantly function being differentiated at gps data.

(2) calculating three axle inertially stabilized platform initial coordinate is ox _b′y _b′z _b′Relatively local geographic coordinate system ox _ny _nz _nBe ox in three axle inertially stabilized platform initial coordinate _b′y _b′z _b′Under angular velocity

Due to

$w_{\mathrm{in}}^n=w_{\mathrm{ie}}^n+w_{\mathrm{en}}^n$

Wherein, Be local geographic coordinate system ox _ny _nz _nThe relative inertness coordinate system is at local geographic coordinate system ox _ny _nz _nUnder angular velocity, For terrestrial coordinate system relative inertness coordinate system at local geographic coordinate system ox _ny _nz _nUnder angular velocity,

Be local geographic coordinate system ox _ny _nz _nRelatively spherical coordinate system is at local geographic coordinate system ox _ny _nz _nUnder angular velocity, and

$w_{\mathrm{ie}}^n=\left[\begin{array}{c}0\\ \cos \left(\mathrm{Lat}\right)\\ \sin \left(\mathrm{Lat}\right)\end{array}\right]$

$w_{\mathrm{en}}^n=\left[\begin{array}{c}-V_N^n/R_M\\ V_E^n/R_N\\ V_E^n\tan \left(\mathrm{Lat}\right)/R_N\end{array}\right]$

Wherein, Lat is local latitude, For flight carrier at local geographic coordinate system ox _ny _nz _nUnder east orientation speed,

For flight carrier at local geographic coordinate system ox _ny _nz _nUnder north orientation speed, R _MAnd R _NBe respectively the local meridian circle principal radius of curvature and the local prime vertical principal radius of curvature.

Can get

$w_{\mathrm{in}}^b=C_n^b{w}_{\mathrm{in}}^n$

Due to

$w_{{\mathrm{ib}}^{\′}}^b=w_{\mathrm{ib}}^b-w_{b^{\′}b}^b$

Wherein,

Three axle inertially stabilized platform inner frame coordinate system ox for gyroscope output _by _bz _bThe relative inertness coordinate system is at three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bUnder angular velocity,

Be that three axle inertially stabilized platform initial coordinate are ox _b′y _b′z _b′The relative inertness coordinate system is at three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bUnder angular velocity.

Therefore can get

$w_{{\mathrm{nb}}^{\′}}^{b^{\′}}=C_b^{b^{\′}}(w_{{\mathrm{ib}}^{\′}}^b-w_{\mathrm{in}}^b)$

5, GPS position data and speed data are carried out the dynamic lever arm compensation

(1) the GPS position data is carried out the dynamic lever arm compensation

Gps data IMU constantly measures center O _IWith gps antenna phase center O _GBetween lever arm l ⁿ

$l^n=C_{b^{\′}}^n{l}^{b^{\′}}=\left[\begin{array}{c}{l}_E^n\\ l_N^n\\ l_U^n\end{array}\right]$

Wherein,

Be lever arm l ⁿAt local geographic coordinate system ox _ny _nz _nUnder east component,

Be lever arm l ⁿAt local geographic coordinate system ox _ny _nz _nUnder north component,

Be lever arm l ⁿAt local geographic coordinate system ox _ny _nz _nUnder the sky to component.

Gps antenna phase center O _GPosition data

Compensate by lever arm the IMU that obtains and measure center O _IPosition data

For

$P_{\mathrm{IMU}}^n=P_{\mathrm{GPS}}^n-l^n=\left[\begin{array}{c}\mathrm{Lat}-l_N^n/R_M\\ \mathrm{Lon}-l_E^n/R_N/\cos \left(\mathrm{Lat}\right)\\ H-l_U^n\end{array}\right]$

Wherein, Lat, Lon, H are respectively latitude, longitude and the height of GPS output.

(2) the GPS speed data is carried out the dynamic lever arm compensation

Gps antenna phase center O _GSpeed data

Compensate by lever arm the IMU that obtains and measure center O _ISpeed data

For

$V_{\mathrm{IMU}}^n=V_{\mathrm{GPS}}^n-C_{b^{\′}}^n{V}_l^{b^{\′}}$

Wherein

For the GPS speed data is ox in three axle inertially stabilized platform initial coordinate _b′y _b′z _b′Under speed lever arm error, calculated by following formula

$V_l^{b^{\′}}=w_{{\mathrm{nb}}^{\′}}^{b^{\′}}\×l^{b^{\′}}$

GPS position data after compensation and speed data and inertial data are merged, obtain the kinematic parameter of optimum.

6, repeating step 2 is to step 5, until the processing of POS system data finishes.

The content that is not described in detail in instructions of the present invention belongs to the known prior art of this area professional and technical personnel.

Claims (1)

1. an airborne remote sensing with position and orientation measurement system (POS) dynamic lever arm compensating method, is characterized in that comprising the following steps:

Step (1), under three axle inertially stabilized platform initial coordinate systems, measure respectively the lever arm between three axle inertially stabilized platform centers and gps antenna phase center

And three lever arm between axle inertially stabilized platform center and Inertial Measurement Unit (IMU) measurement center Described three axle inertially stabilized platform initial coordinate are ox _b'y _b′z _b'Be the photoelectric coder of the three axle inertially stabilized platforms inner frame coordinate system when being output as zero, ox _b'y _b′z _b'Coordinate system represents with b';

Step (2), the calculating gps data moment three axle inertially stabilized platform initial coordinate are tied to the Direct cosine matrix of local geographic coordinate system; The computation process that the described gps data moment three axle inertially stabilized platform initial coordinate are tied to the Direct cosine matrix of local geographic coordinate system is:

1) calculating the gps data moment three axle inertially stabilized platform initial coordinate is ox _b'y _b′z _b′To three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bDirect cosine matrix

$\left[\begin{array}{c}{\mathrm{\γ}}_1\\ {\mathrm{\θ}}_1\\ {\mathrm{\ψ}}_1\end{array}\right]=\left[\begin{array}{c}(P_{\mathrm{Ay}}^{+}-P_{\mathrm{Ay}}^{-})(T_{\mathrm{GPS}}-T_A^{-})/(T_A^{+}-T_A^{-})+P_{\mathrm{Ay}}^{-}\\ (P_{\mathrm{Ax}}^{+}-P_{\mathrm{Ax}}^{-})(T_{\mathrm{GPS}}-T_A^{-})/(T_A^{+}-T_A^{-})+P_{\mathrm{Ax}}^{-}\\ (P_{\mathrm{Az}}^{+}-P_{\mathrm{Az}}^{-})(T_{\mathrm{GPS}}-T_A^{-})/(T_A^{+}-T_A^{-})+P_{\mathrm{Az}}^{-}\end{array}\right]$

$C_{b^{\′}}^b=\left[\begin{array}{ccc}\cos \left({\mathrm{\ψ}}_1\right)& \sin \left({\mathrm{\ψ}}_1\right)& 0\\ -\sin \left({\mathrm{\ψ}}_1\right)& \cos \left({\mathrm{\ψ}}_1\right)& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{ccc}1& 0& 0\\ 0& \cos \left({\mathrm{\θ}}_1\right)& \sin \left({\mathrm{\θ}}_1\right)\\ 0& -\sin \left({\mathrm{\θ}}_1\right)& \cos \left({\mathrm{\θ}}_1\right)\end{array}\right]\left[\begin{array}{ccc}\cos \left({\mathrm{\γ}}_1\right)& 0& -\sin \left({\mathrm{\γ}}_1\right)\\ 0& 1& 0\\ \sin \left({\mathrm{\γ}}_1\right)& 0& \cos \left({\mathrm{\γ}}_1\right)\end{array}\right]$

Wherein, γ ₁The angle is that the gps data moment three axle inertially stabilized platform housings are with respect to the angle of the three initial housings rotations of axle inertially stabilized platform, θ ₁The angle is that the gps data moment three axle inertially stabilized platform centers are with respect to the angle of the three initial centers rotations of axle inertially stabilized platform, ψ ₁The angle is the angle that the gps data moment three axle inertially stabilized platform inside casings rotate with respect to the three initial inside casings of axle inertially stabilized platform,

With

Be the photoelectric coder data of gps data inertially stabilized platform three axles that before the moment, sampling obtains,

With

Be the gps data photoelectric coder data of inertially stabilized platform three axles that obtain of post-sampling constantly, T _GPSBe the gps data UTC time constantly,

For

With

The data sampling UTC time constantly,

For

With

The data sampling UTC time constantly;

2) calculate gps data three axle inertially stabilized platform inner frame coordinate system ox constantly _by _bz _bTo local geographic coordinate system ox _ny _nz _nDirect cosine matrix

$C_b^n=\left[\begin{array}{ccc}{\cos \mathrm{\γ}}_2\cos {\mathrm{\ψ}}_2+{\sin \mathrm{\γ}}_2\sin {\mathrm{\θ}}_2{\sin \mathrm{\ψ}}_2& \cos {\mathrm{\θ}}_2{\sin \mathrm{\ψ}}_2& {\sin \mathrm{\γ}}_2{\cos \mathrm{\ψ}}_2-{\cos \mathrm{\γ}}_2{\sin \mathrm{\θ}}_2{\sin \mathrm{\ψ}}_2\\ {-\cos \mathrm{\γ}}_2{\sin \mathrm{\ψ}}_2+{\sin \mathrm{\γ}}_2{\sin \mathrm{\θ}}_2{\cos \mathrm{\ψ}}_2& {\cos \mathrm{\θ}}_2{\cos \mathrm{\ψ}}_2& -{\sin \mathrm{\γ}}_2{\sin \mathrm{\ψ}}_2-{\cos \mathrm{\γ}}_2{\sin \mathrm{\θ}}_2{\cos \mathrm{\ψ}}_2\\ -{\sin \mathrm{\γ}}_2{\cos \mathrm{\θ}}_2& {\sin \mathrm{\θ}}_2& {\cos \mathrm{\γ}}_2{\cos \mathrm{\θ}}_2\end{array}\right]$

Wherein, γ ₂, θ ₂, ψ ₂Respectively three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bRelatively local geographic coordinate system ox _ny _nz _nRoll angle, the angle of pitch and course angle;

3) calculating the gps data moment three axle inertially stabilized platform initial coordinate is ox _b'y _b′z _b′To local geographic coordinate system ox _ny _nz _nDirect cosine matrix

$C_{b^{\′}}^n=C_b^n{C}_{b^{\′}}^b;$

Step (3), the lever arm that utilizes step (1) to obtain

With

And the Direct cosine matrix that obtains of step (2), calculate gps data constantly IMU measure dynamic lever arm between center and gps antenna phase center, computation process is:

1) calculate gps data three axle inertially stabilized platform center O constantly _PMeasure center O with IMU _IBetween lever arm

$l_2^b=l_{02}^{b^{\′}}$

$C_b^{b^{\′}}=C_{b^{\′}}^{\mathrm{bT}}$

$l_2^{b^{\′}}=C_b^{b^{\′}}{l}_2^b$

Wherein For at three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bLower three axle inertially stabilized platform center O _PMeasure center O with IMU _IBetween lever arm, For

Transposition;

2) calculate gps data IMU measurement constantly center O _IWith gps antenna phase center O _GBetween dynamic lever arm l ^b'

$l_1^{b^{\′}}=l_{01}^{b^{\′}}$

$l^{b^{\′}}=l_1^{b^{\′}}-l_2^{b^{\′}};$

Step (4), the Direct cosine matrix that utilizes step (2) to obtain calculate the three relatively local geographic coordinates of axle inertially stabilized platform initial coordinate system and tie up to angular velocity under three axle inertially stabilized platform initial coordinate systems, and computation process is:

1) calculate three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bRelative three axle inertially stabilized platform initial coordinate are ox _b'y _b′z _b'At three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bUnder angular velocity

$w_{b^{\′}b}^b=\left[\begin{array}{c}{w}_x\\ w_y\\ w_z\end{array}\right]=\left[\begin{array}{c}(P_{\mathrm{Ax}}^{+}-P_{\mathrm{Ax}}^{-})/T_s\\ (P_{\mathrm{Ay}}^{+}-P_{\mathrm{Ay}}^{-})/T_s\\ (P_{\mathrm{Az}}^{+}-P_{\mathrm{Az}}^{-})/T_s\end{array}\right]$

T wherein _sIt is the photoelectric coder sampling period of three axle inertially stabilized platforms;

2) calculating three axle inertially stabilized platform initial coordinate is ox _b'y _b′z _b'Relatively local geographic coordinate system ox _ny _nz _nBe ox in three axle inertially stabilized platform initial coordinate _b'y _b′z _b'Under angular velocity

$w_{{\mathrm{ib}}^{\′}}^b=w_{\mathrm{ib}}^b-w_{b^{\′}b}^b$

$w_{\mathrm{ie}}^n=\left[\begin{array}{c}0\\ \cos \left(\mathrm{Lat}\right)\\ \sin \left(\mathrm{Lat}\right)\end{array}\right]$

$w_{\mathrm{en}}^n=\left[\begin{array}{c}-V_N^n/R_M\\ V_E^n/R_N\\ V_E^n\tan \left(\mathrm{Lat}\right)/R_N\end{array}\right]$

$w_{\mathrm{in}}^n=w_{\mathrm{ie}}^n+w_{\mathrm{en}}^n$

$w_{\mathrm{in}}^b=C_n^b{w}_{\mathrm{in}}^n$

$w_{{\mathrm{nb}}^{\′}}^{b^{\′}}=C_b^{b^{\′}}(w_{{\mathrm{ib}}^{\′}}^b-w_{\mathrm{in}}^b)$

Wherein, Three axle inertially stabilized platform inner frame coordinate system ox for gyroscope output _by _bz _bThe relative inertness coordinate system is at three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bUnder angular velocity,

Be that three axle inertially stabilized platform initial coordinate are ox _b'y _b′z _b'The relative inertness coordinate system is at three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bUnder angular velocity,

For terrestrial coordinate system relative inertness coordinate system at local geographic coordinate system ox _ny _nz _nUnder angular velocity,

Be local geographic coordinate system ox _ny _nz _nRelatively spherical coordinate system is at local geographic coordinate system ox _ny _nz _nUnder angular velocity, Lat is local latitude,

For flight carrier at local geographic coordinate system ox _ny _nz _nUnder east orientation speed,

For flight carrier at local geographic coordinate system ox _ny _nz _nUnder north orientation speed, R _MAnd R _NBe respectively the local meridian circle principal radius of curvature and the local prime vertical principal radius of curvature,

Be local geographic coordinate system ox _ny _nz _nThe relative inertness coordinate system is at local geographic coordinate system ox _ny _nz _nUnder angular velocity,

Be local geographic coordinate system ox _ny _nz _nThe relative inertness coordinate system is at three axle inertially stabilized platform inner frame coordinate system ox _by _bz _bUnder angular velocity;

The angular velocity that step (5), the Direct cosine matrix that obtains based on step (2), dynamic lever arm that step (3) obtains and step (4) obtain, GPS position data and speed data are carried out the dynamic lever arm compensation, and the gps data after compensating and inertial data merge, and obtains optimum kinematic parameter; The described computation process that GPS position data and speed data are carried out the dynamic lever arm compensation is:

1) the GPS position data is carried out the dynamic lever arm compensation

$l^n=C_{b^{\′}}^n{l}^{b^{\′}}=\left[\begin{array}{c}{l}_E^n\\ l_N^n\\ l_U^n\end{array}\right]$

$P_{\mathrm{IMU}}^n=P_{\mathrm{GPS}}^n-l^n=\left[\begin{array}{c}\mathrm{Lat}-l_N^n/R_M\\ \mathrm{Lon}-l_E^n/R_N/\cos \left(\mathrm{Lat}\right)\\ H-l_U^n\end{array}\right]$

Wherein,

Be lever arm l ⁿAt local geographic coordinate system ox _ny _nz _nUnder east component,

Be lever arm l ⁿAt local geographic coordinate system ox _ny _nz _nUnder north component,

Be lever arm l ⁿAt local geographic coordinate system ox _ny _nz _nUnder the sky to component, l ⁿBe gps data IMU measurement constantly center O _IWith gps antenna phase center O _GBetween lever arm, Lat, Lon, H are respectively latitude, longitude and the height of GPS output,

Gps antenna phase center O for GPS output _GPosition data,

Measure center O for compensate the IMU that obtains by lever arm _IPosition data

2) the GPS speed data is carried out the dynamic lever arm compensation

$V_l^{b^{\′}}=w_{n{b}^{\′}}^{b^{\′}}\×l^{b^{\′}}$

$V_{\mathrm{IMU}}^n=V_{\mathrm{GPS}}^n-C_{b^{\′}}^n{V}_l^{b^{\′}}$

Wherein,

For the GPS speed data is ox in three axle inertially stabilized platform initial coordinate _b′y _b′z _b′Under speed lever arm error, * be multiplication cross,

Gps antenna phase center O for GPS output _GSpeed data,

Measure center O for compensate the IMU that obtains by lever arm _ISpeed data;

Step (6), repeating step (2) are to step (5), until the processing of POS system data finishes.

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