CN103217987B - 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 for quick satellite dynamic imaging

Technical field

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

Background technology

The dynamic imaging of agile satellite refers to that satellite carries out imaging in the motor-driven middle unlatching optics useful load of three-axis attitude, and in imaging process, adjustment optical axis points to realize complicated imaging task over the ground in real time.The synergy of and orbital motion motor-driven due to three-axis attitude, satellite imagery performs usefulness and is greatly improved.Therefore, dynamic imaging techniques will become the important directions of following space flight military satellite development.

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

For the push-scanning image mode of absolute orientation, in order to meet imaging demand, " spaceborne TDI-CCD pushes away the drift angle of sweeping camera and calculates and compensate " in (Shanghai space flight the 6th phase in 2006) literary composition Yuan Xiaokang deeply derived azimuth deviation and pitching migration imaging time camera drift angle computing formula, and propose the method adopting satellite driftage control and compensation camera drift angle, dynamically change the configuration direction of TDICCD linear array, make it consistent with target image motion direction all the time; In " batch (-type) of drift angle of space camera adjusts in real time " (optical precision engineering the 17th volume the 8th phase in 2009) literary composition, Yu Tao etc. propose and install drift angle control system on stars: drift angle controller, power amplification circuit, drift angle executive component, measuring sensor and adjusting mechanism etc. realize drift angle adjustment.When adopting said method to compensate the attitude of satellite, there is following problem:

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

(2) the pose compensation technology in literary composition is the push-scanning image mode based on absolute orientation, and pose compensation technology controls except drift angle, and the pitching of satellite and rate of roll nominal value are zero, cannot realize carrying out imaging in three-axis attitude mobile process.

(3) the push-scanning image mode of the absolute orientation in literary composition, due to by 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, and imaging fabric width is limited.For the imaging fabric width that single push-scanning image fabric width is 20km, even if carried out the joining image-forming of five bands, also 100km is only had to the covering fabric width of thing longitudinal; And the wide dynamic imaging techniques of wide cut, can more than 350km be reached to the covering fabric width of thing longitudinal.

(4) absolute orientation push-scanning image mode in literary composition, owing to not having dynamic imaging ability, imaging process carries out push-scanning image after stablizing based on pose adjustment, 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 SEE 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, provides a kind of attitude adjusting method for quick satellite dynamic imaging, can carry out imaging in three-axis attitude mobile process, can realize the wide imaging of wide cut of thing longitudinal.

Technical scheme of the present invention is:

For an attitude adjusting method for quick satellite dynamic imaging, the wide imaging of wide cut in pose adjustment process can be realized; First, the roll angle of satellite is adjusted to realize the push-scanning image to east-west direction; Then, the angle of pitch of satellite and rate of pitch is adjusted to compensate the convected velocity of orbital motion on earth's surface; Finally, the crab angle of satellite is adjusted to realize the control to drift angle.

The roll angle Changing Pattern of satellite is: wherein for the rate of roll of satellite, for the roll angle of imaging initial time, t represents any time in imaging process, for the roll angle of t;

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

θ _t＝θ _b-ω _θtt；

Wherein, i is inclination of satellite orbit, ω _ofor satellite transit angular velocity, ω _efor rotational-angular velocity of the earth, R _efor earth radius, H is satellite height overhead, δ _dfor the geographic latitude of imageable target point, b is geocentric angle OO when measuring with earth radius _ethe arc length that T is corresponding, O is substar, O _efor the earth's core, T is corresponding moment roll angle side-sway point; θ _bfor the roll angle of imaging initial time, θ _tfor the angle of pitch of t, ω _{θ t}for the rate of pitch of t;

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 _tfor the crab angle of t, V _ηfor pushing away of dynamic imaging processes Satellite sweeps surface projection speed.

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

The present invention, on the basis of optics useful load image-forming principle, analyzes the Specifications of dynamic imaging, from the viewpoint of platform and load two dynamic imaging techniques, proposes dynamic imaging attitude adjusting method, improves imaging execution usefulness.

Attitude adjusting method of the present invention can be applied to satellite in three-axis attitude mobile process, open the dynamic imaging techniques that optics useful load carries out imaging, improves satellite covering power to thing longitudinal when individual pen passes by by the real-time adjustment of attitude; More than 350km can be reached to the covering fabric width of thing longitudinal.

When adopting TDICCD optics useful load to carry out imaging, need to ensure that the direction of image motion velocity is consistent with ground velocity direction, otherwise the image obtained there will be as moving problem.It is consistent with ground velocity direction that the present invention can realize image motion velocity direction by the adjustment of crab angle, solves the drift angle problem in dynamic imaging processes; Thus the picture that can solve in the wide imaging process of wide cut moves problem, obtain high-quality image.

Accompanying drawing explanation

Fig. 1 is the wide dynamic imaging processes schematic diagram of wide cut of the present invention;

Fig. 2 is that the wide dynamic imaging of wide cut compensates ground velocity schematic diagram;

Fig. 3 is satellite orbit coordinate system schematic diagram;

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

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

Embodiment

Attitude adjusting method principle of the present invention is as follows: for the imaging demand that wide cut is wide, when satellite orbiting, controls the roll angle of satellite to realize the push-scanning image to east-west direction; Meanwhile, the angle of pitch of satellite and the angular rate compensation orbital motion convected velocity at surface projection is controlled; Finally, on the basis of TDICCD image-forming principle, the crab angle of adjustment satellite realizes the control to drift angle.

As shown in Figure 1, the wide dynamic imaging processes of wide cut is as follows: satellite around body X-axis with angular velocity push-scanning image is carried out perpendicular to flight path direction; Imaging initial time is t ₁, now satellite is positioned at S ₁place, optical axis points to terrain object point D ₁; Satellite, while rolling push-scanning image, due to the convected motion of orbital motion, needs the control carrying out pitch orientation to compensate the convected velocity of orbital motion on earth's surface, realizes at t ₂, t ₃,, t _nin the moment, satellite is positioned at S ₂, S ₃,, S _n, optical axis points to terrain object point D ₂, D ₃,, D _n, thus realize the imaging band perpendicular to flight path direction, form wide cut imaging capability.

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

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

In Fig. 1, imaging initial time is t ₁, now roll angle is the angle of pitch is θ _b, crab angle is β; T represents any time in imaging process, and corresponding roll angle is the angle of pitch is θ _t, crab angle is β _t; Corresponding rate of roll is rate of pitch is ω _{θ t}.B is geocentric angle OO when measuring with earth radius _ethe arc length that T is corresponding, O is substar, O _efor the earth's core, T is corresponding moment roll angle side-sway point;

When satellite optical axis points to S ₁d ₁time, optical axis in the projection convected velocity on earth's surface 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 the band imaging perpendicular to flight path direction, completing the push-scanning image of an east-west direction, needing to control pitch axis and compensating orbital motion.

When Fig. 2 shows satellite orbiting, the convected velocity of orbital motion on earth's surface and the vector correlation figure of earth rotation speed.Being obtained by map analysis, in order to realize the wide imaging demand of wide cut, needing to compensate ground velocity, analyzing the ground velocity be 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 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:

Compensate on the basis of ground velocity at the angle of pitch, rolling due to satellite pushes away the impact of sweeping with earth rotation, ground imageable target point photography ground velocity and rolling can be caused to push away sweep direction to there is angle, needs to be corrected by crab angle, to guarantee load start imaging, meet image quality requirements; By the basic definition of drift angle, obtain drift angle Changing Pattern, adopt crab angle to correct drift angle, crab angle adjustment law is as follows:

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

Note: V _ηfor pushing away of dynamic imaging processes Satellite sweeps surface projection speed.

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

As shown in Figure 4, the body coordinate system SXYZ of satellite is fixed on celestial body, and wherein, body X-axis is the axis of rolling, and body Y-axis is pitch axis, and body Z axis is yaw axis.When satellite orbiting, the body coordinate system SXYZ of satellite overlaps with orbital coordinate system Sxyz; When satellite carry out thing side-sway push away sweep time, the body coordinate system SXYZ of satellite and orbital coordinate system Sxyz has a side-sway angle.

Attitude adjusting method of the present invention is as follows:

During satellite orbiting, satellite around body X-axis with angular velocity carry out the wide rolling push-scanning image of wide cut; Roll angle changing Pattern obtained by formula (4).In order to realize the wide band imaging of east-west direction wide cut, satellite carries out pitch control subsystem around body Y-axis again, pitching angle theta _twith rate of pitch ω _{θ t}changing Pattern obtained by formula (5), (6); Finally, according to the Changing Pattern of formula (7) crab angle, satellite carries out driftage around body Z axis and controls.

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

The content be not described in detail in instructions of the present invention belongs to the known technology of those skilled in the art.

Claims (1)

1., for an attitude adjusting method for quick satellite dynamic imaging, the wide imaging of wide cut in pose adjustment process can be realized; It is characterized in that: first, the roll angle of adjustment satellite is to realize the push-scanning image to east-west direction; Then, the angle of pitch of satellite and rate of pitch is adjusted to compensate the convected velocity of orbital motion on earth's surface; Finally, the crab angle of satellite is adjusted to realize the control to drift angle;

The roll angle Changing Pattern of satellite is: wherein for the rate of roll of satellite, for the roll angle of imaging initial time, t represents any time in imaging process, for the roll angle of t;

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

θ _t＝θ _b-ω _θtt；

Wherein, i is inclination of satellite orbit, ω _ofor satellite transit angular velocity, ω _efor rotational-angular velocity of the earth, R _efor earth radius, H is satellite height overhead, δ _dfor the geographic latitude of imageable target point, b is geocentric angle OO when measuring with earth radius _ethe arc length that T is corresponding, O is substar, O _efor the earth's core, T is corresponding moment roll angle side-sway point; θ _bfor the roll angle of imaging initial time, θ _tfor the angle of pitch of t, ω _{θ t}for the rate of pitch of t;

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 _tfor the crab angle of t, V _ηfor pushing away of dynamic imaging processes Satellite sweeps surface projection speed.