CN103217987A - Agile satellite dynamic imaging posture adjustment method - Google Patents

Abstract

The invention discloses an agile satellite dynamic imaging posture adjustment method which can achieve wide-width imaging in a posture adjusting process. Firstly, a rolling angle of a satellite is adjusted to achieve push-scan imaging in the east-west direction; then, a pitch angle and pitch angular speed of the satellite are adjusted to compensate transport velocity of rail motion on the earth surface; and finally, a yaw angle of the satellite is adjusted to control a drift angle. The posture adjustment method can be applied to dynamic imaging technique for the satellite to open optical effective load to image in a triaxial attitude maneuver process. The covering power of the satellite in the east-west longitude direction in one-loop transit is improved through real-time posture adjustment. The covering width in the east-west longitude direction can reach more than 350km.

Description

A kind of attitude adjusting method that is used for quick satellite dynamic imaging

Technical field

The present invention relates to a kind of attitude adjusting method that is used for quick satellite dynamic imaging.

Background technology

The dynamic imaging of agile satellite is meant that satellite opens the optics useful load and carry out imaging in three-axis attitude is motor-driven, adjusts optical axis in real time and point to over the ground to realize complicated imaging task in imaging process.Because three-axis attitude is motor-driven and the synergy of orbital motion, satellite imagery is carried out usefulness and is greatly improved.Therefore, the dynamic imaging technology will become the important directions of following space flight military satellite development.

The push-scanning image pattern of absolute orientation is generally adopted in the band imaging of existing satellite, and the push-scanning image direction is consistent with track running direction, and the band of formation is basically parallel to orbital direction, and the imaging fabric width is subjected to the restriction of optics useful load fabric width; In fact utilized orbital motion in the imaging process, except drift angle control, the pitching of satellite and rate of roll nominal value are zero.Yet the dynamic imaging technology also needs to control the pitching and the rate of roll of satellite except drift angle control, adjusts the pitching of satellite and roll angle in real time to realize specific imaging task.

Push-scanning image mode for absolute orientation, in order to satisfy imaging demand, the drift angle computing formula of camera when Yuan Xiaokang has deeply derived azimuth deviation and pitching migration imaging in " spaceborne TDI-CCD pushes away the drift angle of sweeping camera and calculates and compensation " (2006 the 6th phases of Shanghai space flight) literary composition, and proposed to adopt the method for satellite driftage control compensation camera drift angle, dynamically change the configuration direction of TDICCD linear array, make it consistent with target image drift direction all the time; Yu Tao etc. has proposed the drift angle control system is installed on star in " batch (-type) of drift angle of space camera is adjusted in real time " (optical precision engineering 2009 the 17th volume the 8th phase) literary composition: drift angle controller, power amplification circuit, drift angle executive component, measuring sensor and adjusting mechanism etc. are realized the drift angle adjustment.When adopting said method that the attitude of satellite is compensated, there is following problem:

(1) in the literary composition in the mentioned imaging pattern, the imaging fabric width of satellite borne sensor is less, and normally less circle or rectangular area can't effectively cover the extensive area target, and imaging task is single;

(2) the attitude compensation technique in the literary composition is based on the push-scanning image mode of absolute orientation, and the attitude compensation technique is controlled except drift angle, and the pitching of satellite and rate of roll nominal value are zero, can't be implemented in and carry out imaging in the three-axis attitude mobile process.

(3) the push-scanning image mode of the absolute orientation in the literary composition, owing to be subjected to the restriction of optical remote sensor imaging fabric width, what adopt for large-scale regional imaging is the joining image-forming mode of multi-ribbon, the imaging fabric width is limited.For single push-scanning image fabric width is the imaging fabric width of 20km, even carried out the joining image-forming of five bands, the covering fabric width of thing longitudinal is also had only 100km; And the wide dynamic imaging technology of wide cut can reach more than the 350km the covering fabric width of thing longitudinal.

(4) absolute orientation push-scanning image mode in the literary composition, owing to do not have the dynamic imaging ability, imaging process is based on carries out push-scanning image after the attitude adjustment is stablized, the attitude maneuver time adds that stabilization time is consuming time longer, cause the effective imaging time of satellite to reduce, side by side the visible time window of surface imaging target shortens.

Based on above analysis, the attitude adjusting method of the push-scanning image mode of absolute orientation can not adapt to the requirement of dynamic imaging.

Summary of the invention

Technical matters to be solved by this invention is: overcome the deficiencies in the prior art, a kind of attitude adjusting method that is used for quick satellite dynamic imaging is provided, can carry out imaging in the three-axis attitude mobile process, can realize the wide imaging of wide cut of thing longitudinal.

Technical scheme of the present invention is:

A kind of attitude adjusting method that is used for quick satellite dynamic imaging can be realized the wide imaging of wide cut in the attitude adjustment process; At first, adjust the roll angle of satellite to realize push-scanning image to east-west direction; Then, the angle of pitch of adjustment satellite and rate of pitch are with the convected velocity of compensation orbital motion on the face of land; At last, adjust the crab angle of satellite to realize control to drift angle.

The roll angle Changing Pattern of satellite is:

Wherein

Be the rate of roll of satellite,

Be the roll angle in the initial moment of imaging, t represents any time in the imaging process,

Be t roll angle constantly;

The angle of pitch of satellite and the Changing Pattern of rate of pitch are as follows:

θ _t＝θ _b-ω _θtt；

Wherein, i is an inclination of satellite orbit, ω _oBe satellite transit angular velocity, ω _eBe rotational-angular velocity of the earth, R _eBe earth radius, H is a satellite height overhead, δ _DBe the geographic latitude of imageable target point, b is geocentric angle OO when measuring with earth radius _eThe arc length of T correspondence, O is a substar, O _eBe the earth's core, T is corresponding roll angle constantly

The side-sway point; θ _bBe the roll angle in the initial moment of imaging, θ _tBe the t angle of pitch constantly, ω _{θ t}Be t rate of pitch constantly;

The Changing Pattern of the crab angle of satellite is:

${\mathrm{\β}}_t=\arctan \frac{{\mathrm{\ω}}_e{R}_e\cos {\mathrm{\δ}}_D\sin (\mathrm{\π}/2-i)}{V_{\mathrm{\η}}+{\mathrm{\ω}}_e{R}_e\cos {\mathrm{\δ}}_D\cos (\mathrm{\π}/2-i)}$

Wherein, β _tBe t crab angle constantly, V _ηBe pushing away of satellite in the dynamic imaging process table projection speed of sweeping the floor.

The present invention's advantage compared with prior art is:

The present invention analyzes the correlation technique index of dynamic imaging on the basis of optics useful load image-forming principle, consider the dynamic imaging technology from platform and two aspects of load, proposes the dynamic imaging attitude adjusting method, improves imaging execution usefulness.

Attitude adjusting method of the present invention can be applied to satellite and open the dynamic imaging technology that the optics useful load is carried out imaging in the three-axis attitude mobile process, and real-time adjustment by attitude has improved satellite covering power to the thing longitudinal when individual pen passes by; Covering fabric width to the thing longitudinal can reach more than the 350km.

When adopting TDICCD optics useful load to carry out imaging, need to guarantee that the direction of image drift speed is consistent with the ground velocity direction, otherwise the image drift problem can appear in the image that obtains.The present invention can realize that by the adjustment of crab angle the image drift velocity reversal is consistent with the ground velocity direction, solves the drift angle problem in the dynamic imaging process; Thereby can solve the image drift problem in the wide imaging process of wide cut, obtain high-quality image.

Description of drawings

Fig. 1 is the wide dynamic imaging process of a wide cut of the present invention synoptic diagram;

Fig. 2 is the wide dynamic imaging compensation of a wide cut ground velocity synoptic diagram;

Fig. 3 is a satellite orbit coordinate system synoptic diagram;

Fig. 4 is satellite body coordinate system and satellite orbit coordinate system synoptic diagram;

Fig. 5 is the imaging effect synoptic diagram of attitude adjusting method of the present invention.

Embodiment

Attitude adjusting method principle of the present invention is as follows: for the wide imaging demand of wide cut, when the satellite orbiting, the roll angle of control satellite is to realize the push-scanning image to east-west direction; Simultaneously, the angle of pitch of control satellite and angular rate compensation orbital motion are in the convected velocity of surface projection; At last, on the basis of TDICCD image-forming principle, adjust the control of the crab angle realization of satellite to drift angle.

As shown in Figure 1, the wide dynamic imaging process of wide cut is as follows: satellite around the body X-axis with angular velocity

Carry out push-scanning image perpendicular to the flight path direction; The imaging initial time is t ₁, this moment, satellite was positioned at S ₁The place, optical axis directed towards ground impact point D ₁Satellite is in the rolling push-scanning image, because the convected motion of orbital motion, the control that need carry out pitch orientation is implemented in t with the convected velocity of compensation orbital motion on the face of land ₂, t ₃,,, t _nConstantly, satellite is positioned at S ₂, S ₃,,, S _n, optical axis directed towards ground impact point D ₂, D ₃,,, D _nThereby, realize imaging band perpendicular to the flight path direction, form the wide cut imaging capability.

Below, the attitude angle Changing Pattern in the wide imaging process of concrete analysis wide cut:

If satellite transit is the track of i in the inclination angle, angular velocity is ω _oSatellite altitude is H, ω _e, R _eBe respectively rotational-angular velocity of the earth and radius, δ _DBe the geographic latitude of imageable target D, h is the target floor height.

The initial moment of imaging is t among Fig. 1 ₁, this moment, roll angle was The angle of pitch is θ _b, crab angle is β; T represents any time in the imaging process, and corresponding roll angle is

The angle of pitch is θ _t, crab angle is β _tCorresponding rate of roll is

Rate of pitch is ω _{θ t}B is geocentric angle OO when measuring with earth radius _eThe arc length of T correspondence, O is a substar, O _eBe the earth's core, T is corresponding roll angle constantly The side-sway point;

When the satellite optical axis points to S ₁D ₁The time, optical axis in the projection convected velocity on the face of land is:

V _D＝ω _o(R _e+h)cosb (1)

D ₁Point earth rotation linear velocity:

V _de＝ω _e(R _e+h)cosδ _D (2)

In order to realize band imaging perpendicular to the flight path direction, finish the push-scanning image of an east-west direction, need control pitch axis compensation orbital motion.

When Fig. 2 had shown the satellite orbiting, orbital motion was at the convected velocity on the face of land and the vector correlation figure of earth rotation speed.Obtained by map analysis, for the imaging demand that realizes that wide cut is wide, need compensate ground velocity, analyzing the ground velocity that is compensated is V _Mend:

V _Mend=| ω _oR _eCosb+ ω _eR _eCos δ _DSin (pi/2-i) | (3)

1. roll angle:

If rate of roll is

Obtaining the roll angle Changing Pattern is:

2. the angle of pitch:

In order to compensate the convected velocity of orbital motion at surface projection, pitching angle theta _tChanging Pattern be:

θ _t＝θ _b-ω _θtt (6)

3. crab angle:

On the basis of angle of pitch compensation ground velocity, because the rolling of satellite pushes away the influence of sweeping with earth rotation, can cause imageable target point photograph ground velocity and rolling in ground to push away and sweep direction and have angle, need proofread and correct by crab angle, to guarantee load start imaging, satisfy the picture quality requirement; By the basic definition of drift angle, obtain the drift angle Changing Pattern, adopt crab angle that drift angle is proofreaied and correct, the crab angle adjustment law is as follows:

${\mathrm{\β}}_t=\arctan \frac{{\mathrm{\ω}}_e{R}_e\cos {\mathrm{\δ}}_D\sin (\mathrm{\π}/2-i)}{V_{\mathrm{\η}}+{\mathrm{\ω}}_e{R}_e\cos {\mathrm{\δ}}_D\cos (\mathrm{\π}/2-i)}---\left(7\right)$

Annotate: V _ηBe pushing away of satellite in the dynamic imaging process table projection speed of sweeping the floor.

Fig. 3 has shown the orbital coordinate system Sxyz of satellite, and the orbit plane of satellite is a coordinate plane, and the z axle points to the earth's core by barycenter, and the x axle is vertical with the z axle and point to the satellite velocities direction in orbit plane, y axle and x, z axle right hand quadrature and with the normal parallel of orbit plane.

As shown in Figure 4, the body coordinate system SXYZ of satellite is fixed on the celestial body, and wherein, the body X-axis is the axis of rolling, and the body Y-axis is a pitch axis, and body Z axle is a yaw axis.When the satellite orbiting, the body coordinate system SXYZ of satellite overlaps with orbital coordinate system Sxyz; Push away when sweeping when satellite carries out the thing side-sway, the body coordinate system SXYZ of satellite and orbital coordinate system Sxyz have a side-sway angle.

Attitude adjusting method of the present invention is as follows:

During the satellite orbiting, satellite around the body X-axis with angular velocity Carry out the wide rolling push-scanning image of wide cut; Roll angle Changing Pattern obtain by formula (4).For the band imaging that realizes that the east-west direction wide cut is wide, satellite carries out pitch control subsystem, pitching angle theta around the body Y-axis again _tWith rate of pitch ω _{θ t}Changing Pattern obtain by formula (5), (6); At last, according to the Changing Pattern of formula (7) crab angle, satellite is around the control of going off course of body Z axle.

As shown in Figure 5, open optics load in the attitude maneuver process, by attitude adjusting method of the present invention, can realize the wide regional imaging of wide cut of thing longitudinal, the imaging execution ability is improved.

The content that is not described in detail in the instructions of the present invention belongs to those skilled in the art's known technology.

Claims (2)

1. an attitude adjusting method that is used for quick satellite dynamic imaging can be realized the wide imaging of wide cut in the attitude adjustment process; It is characterized in that: at first, the roll angle of adjusting satellite is to realize the push-scanning image to east-west direction; Then, the angle of pitch of adjustment satellite and rate of pitch are with the convected velocity of compensation orbital motion on the face of land; At last, adjust the crab angle of satellite to realize control to drift angle.

2. attitude adjusting method according to claim 1 is characterized in that:

The roll angle Changing Pattern of satellite is:

Wherein

Be the rate of roll of satellite,

Be the roll angle in the initial moment of imaging, t represents any time in the imaging process,

Be t roll angle constantly;

The angle of pitch of satellite and the Changing Pattern of rate of pitch are as follows:

θ _t＝θ _b-ω _θtt；

Wherein, i is an inclination of satellite orbit, ω _oBe satellite transit angular velocity, ω _eBe rotational-angular velocity of the earth, R _eBe earth radius, H is a satellite height overhead, δ _DBe the geographic latitude of imageable target point, b is geocentric angle OO when measuring with earth radius _eThe arc length of T correspondence, O is a substar, O _eBe the earth's core, T is corresponding roll angle constantly

The side-sway point; θ _bBe the roll angle in the initial moment of imaging, θ _tBe the t angle of pitch constantly, ω _{θ t}Be t rate of pitch constantly;

The Changing Pattern of the crab angle of satellite is:

${\mathrm{\β}}_t=\arctan \frac{{\mathrm{\ω}}_e{R}_e\cos {\mathrm{\δ}}_D\sin (\mathrm{\π}/2-i)}{V_{\mathrm{\η}}+{\mathrm{\ω}}_e{R}_e\cos {\mathrm{\δ}}_D\cos (\mathrm{\π}/2-i)}$

Wherein, β _tBe t crab angle constantly, V _ηBe pushing away of satellite in the dynamic imaging process table projection speed of sweeping the floor.

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