CN103438888A - Relative navigation method for autonomous rendezvous of space non-operative target - Google Patents

Abstract

The invention relates to a relative navigation method for autonomous rendezvous of a space non-operative target. The relative navigation method comprises: taking a spacecraft relative orbital motion equation as a navigation state equation, taking relative visual angle information measured by a spaceborne CCD (Charge Coupled Device) camera, absolute positioning information output by a GNSS (Global Navigation Satellite System) receiver and relative distance rho information constructed by geometrical constraint as measure quantities, and employing UKF (Unscented kalman filter) filtering algorithm to accurately estimate the relative position and relative speed between a service satellite and the space non-operative target. The relative navigation method is applicable to relative navigation for remote autonomous rendezvous of space non-operative targets. The relative navigation method has the beneficial effects that: under the conditions that the service satellite has no special orbital maneuver and the number of the service satellite is not increased, the high-accuracy relative navigation for medium/long distance autonomous rendezvous of the space non-operative targets with the service satellite can be realized by only depending on the spaceborne CCD camera and the absolute positioning equipment GNSS receiver of the singular service satellite.

Description

A kind of Relative Navigation to the intersection of space non-cooperative Target self-determination

Technical field

The present invention relates to a kind of Relative Navigation to the intersection of space non-cooperative Target self-determination, belong to Space Autonomous Relative Navigation field.

Background technology

Recent two decades comes, for being becoming tight Earth's orbit resource day, fault satellites is repaired in-orbit and the problem such as orbit debris cleaning, various countries have actively launched to utilize robot for space (Servicing spacecraft or service star in-orbit) to service technology researchs in-orbit such as the space non-cooperative targets such as fault satellites, orbit debris are monitored, approach, catch and lengthen the life or leave the right or normal track.Relative Navigation is the gordian technique that spacecraft is served in-orbit, the CCD camera is passive measurement because of it, and having the advantages such as measurement range is wide, precision is high, and equipment volume is little, quality is light, low in energy consumption, is the following desirable Relative Navigation sensor that the space non-cooperative target is served in-orbit.But when the medium and long distance intersection, due to the non-cooperation of target (without communication, without the cooperation marker etc.), the metrical information that the CCD camera can obtain is incomplete, only has relative angle of sight information, there is no direct relative distance information, this Relative Navigation system observability that only just causes carrying out with the CCD camera relative measurement is poor, and Relative Navigation realizes that difficulty is large.Addressing this problem at present the approach that realizes the high precision Relative Navigation both at home and abroad is all by indirectly estimating the auxiliary Relative Navigation of relative distance information, specifically mainly contains two large class schemes:

1, the orbit maneuver scheme, see document: Li J.R., Li H.Y, Tang G.J., Research on the strategy of angles-only relative navigation for autonomous rendezvous[J] .SCIENCE CHINA Technological Sciences, 2011, 54 (7): 1865-1872. and document: Woffinden D.C., Geller D.K., Optimal Orbital Rendezvous Maneuvering for Angles-Only Navigation[J] .Journal of Guidance control and Dynamics, 2009, 32 (4), 1382-1387.

2, Double Satellite scheme, be shown in document: Su Jianmin, Dong Yunfeng. non-cooperation maneuvering target Space-based Angle Measured orbit determination research [J]. and Aerospace Control, 2011,29(3): 36-42; And document: old system, Xu Shijie, Jia Yinghong. the noncooperative target spacecraft Relative Navigation method of guidance that application double vision line vector is measured: China, 101423121A[P] .2009.5.6.And document: Liu Guangming, Liao Ying etc. the space non-cooperative target associating orbit determination method [J] based on Double Satellite. the aerospace journal, 2010,31(9): 2095-2100.

Referring to Fig. 1, Fig. 2.For the orbit maneuver scheme, its essence is that carrying out special orbit maneuver by the service star constructs relative distance information, this scheme may produce material impact to security and the fuel consumption of service star in practice.For the Double Satellite scheme, its essence is by the measurement baseline of double star and construct relative distance information, this scheme needs two satellites or needs the service star need to possess the ability that discharges accompanying flying moonlet and cooperative, it is larger that this is difficult for realization and cost in practice, and the less estimated accuracy of Double Satellites Observation vector angle is lower, and two measurement vectors when parallel relative distance estimate to lose efficacy.Current in only angle measurement air navigation aid of space non-cooperative target, need to pass through special orbit maneuver by a plurality of satellite platform cooperatives or single satellite platform, improve the system observability and solve the poor problem that can not complete Relative Navigation of observability in some situation.

Summary of the invention

The technical matters solved

For fear of the deficiencies in the prior art part, the present invention proposes a kind of Relative Navigation to the intersection of space non-cooperative Target self-determination.

Technical scheme

A kind of Relative Navigation to the intersection of space non-cooperative Target self-determination is characterized in that step is as follows:

Step 1: by service star satellite-based CCD camera tracking observation space non-cooperative target, obtain relative sight line elevation angle ε and relative sight line azimuth angle theta;

Step 2: carry the GNSS receiver by the service star service star is carried out absolute fix and obtains the positional information under inertial system, then by this absolute position, carry out geometry recursion acquisition relative distance, recursion formula is:

${{\mathrm{\ρ}}_t}_k=\sqrt{{\mathrm{\ρ}}_{t_{k-1}}^2+{{\left|\right|r_{G\_t_k}-r_{G\_t_{k-1}}\left|\right|}_2}^2-2{{\mathrm{\ρ}}_t}_k{\left|\right|r_{G\_t_k}-r_{G\_t_{k-1}}\left|\right|}_2\cos \mathrm{\α}}$

Wherein,

for t _kconstantly serve the absolute position vector that spaceborne GNSS provides, ‖ ‖ ₂mean 2 norms, α is t _k-1the line of sight i of unit constantly and the angle of tracker self unit displacement vector delta r;

Step 3: take spacecraft relative track movement equation as the navigational state equation, using sight line elevation angle ε, sight line azimuth angle theta and relative distance ρ as the measurement amount, adopt the UKF filtering algorithm to obtain serving relative position and the relative velocity between star and noncooperative target.

Beneficial effect

A kind of Relative Navigation to the intersection of space non-cooperative Target self-determination that the present invention proposes, take spacecraft relative track movement equation as the navigational state equation, with satellite-based CCD (Charge Coupled Device, charge-coupled image sensor) camera is measured relative angle of sight information and GNSS(Global Navigation Satellite System, GLONASS (Global Navigation Satellite System)) the relative distance ρ information of the absolute fix information of receiver output and geometrical constraint structure is as the measurement amount, adopt UKF(Unscented kalman filter, the Unscented Kalman Filter device) filtering algorithm accurately estimates relative position and the relative velocity between service star and noncooperative target.The present invention is applicable to the autonomous rendezvous Relative Navigation of space non-cooperative target medium-long range.

Beneficial effect of the present invention: can not carry out special orbit maneuver at the service star, do not increase in the situation of service star number amount yet, only rely on spaceborne relative measurement equipment CCD camera and the absolute pointing device GNSS receiver of single service star, just can realize the service star high precision Relative Navigation autonomous rendezvous to space non-cooperative target medium-long range.

The accompanying drawing explanation

Fig. 1 is only angle measurement navigation schematic diagram of coplanar encounter;

Fig. 2 is only angle measurement navigation schematic diagram of non-uniplanar intersection;

Fig. 3 is the present invention program's structured flowchart;

Fig. 4 is how much recursion algorithm for estimating schematic diagram of relative distance of the present invention program;

Fig. 5 is relative position and the speed estimation error curve that the present invention program carries out the Relative Navigation acquisition.

Embodiment

Now in conjunction with the embodiments, the invention will be further described for accompanying drawing:

The structured flowchart of the inventive method as shown in Figure 3, the relative angle of sight information (sight line elevation angle ε and azimuth angle theta) of the CCD camera of usining measurement and the relative distance ρ information of constructing by the absolute fix of GNSS receiver, as the measurement amount, estimate relative position and the relative velocity between service star and noncooperative target by the UKF filtering algorithm.Wherein, the absolute fix information of relative distance ρ by space geometry relation constraint GNSS is also carried out recursion and is obtained, the initial value ρ of relative distance ₀assist and provide by ground or space-based measuring system.Mainly by following three steps, formed:

Step 1, by service star satellite-based CCD camera tracking observation space non-cooperative target, obtain relative sight line elevation angle ε and relative sight line azimuth angle theta;

Step 2, carried the absolute fix of GNSS receiver and carried out the estimation that how much recursion obtains relative distance ρ by the service star.Specific algorithm is as follows:

How much recursion algorithm for estimating schematic diagram of relative distance as shown in Figure 4.Provided the inertial position in a certain moment of noncooperative target by ground or space-based measuring system, the service star is provided the inertial position of its synchronization by spaceborne GNSS, so just can determine the relative distance initial value between two aircraft.No longer need the auxiliary of ground survey after determining initial value, relative distance is afterwards estimated by how much recursive algorithms.Here will serve star the motion that approaches of noncooperative target is divided into to two classes: a class is to approach along direction of visual lines; One class is that non-direction of visual lines approaches.

For approaching along direction of visual lines, the recursion formula of relative distance is

${{\mathrm{\ρ}}_t}_k={{\mathrm{\ρ}}_t}_{k-1}-{\left|\right|r_{G\_t_k}-r_{G\_t_{k-1}}\left|\right|}_2---\left(1\right)$ Wherein, for t _kconstantly serve the absolute position vector that spaceborne GNSS provides, ‖ ‖ ₂mean 2 norms.

Approach for non-direction of visual lines, can determine that rule estimates relative distance by triangle, known leg-of-mutton two length of sides and their angle are determined leg-of-mutton shape according to " limit, corner " rule, can determine the relative distance recursion formula by the cosine law so

${{\mathrm{\ρ}}_t}_k=\sqrt{{\mathrm{\ρ}}_{t_{k-1}}^2+{{\left|\right|r_{G\_t_k}-r_{G\_t_{k-1}}\left|\right|}_2}^2-2{{\mathrm{\ρ}}_t}_k{\left|\right|r_{G\_t_k}-r_{G\_t_{k-1}}\left|\right|}_2\cos \mathrm{\α}}---\left(2\right)$

Wherein, α is t _k-1the line of sight i of unit constantly and the angle of tracker self unit displacement vector delta r.

From formula (2), when α equals 0, formula (2) is equivalent to formula (1), so just the relative distance recursion that direction of visual lines approaches and non-direction of visual lines approaches under both of these case has been united.Therefore, at ground or the auxiliary given initial value ρ of space-based measuring system ₀after, no matter by which kind of direction approach and can be carried out by formula (2) the real-time recursion of relative distance.

Step 3, take spacecraft relative track movement equation as the navigational state equation, usings sight line elevation angle ε, sight line azimuth angle theta and relative distance ρ as the measurement amount, adopts the UKF filtering algorithm to estimate relative position and the relative velocity between service star and noncooperative target.

Specific embodiment: in conjunction with Fig. 5, case verification of the present invention is described, is set as follows design conditions and technical parameter:

1) semi-major axis of orbit of noncooperative target is 6678km, and excentricity is 0.01, and orbit inclination is 60 °, and argument of perigee is 120 °, and right ascension of ascending node is 40 °, and true anomaly is 70 °;

2) the prima facies contraposition is set to [40; 0;-10] km, initial relative velocity is [20; 0; 10] m/s;

3) CCD camera alignment error 10 ^-3rad, measure noise mean square deviation 10 ^-3rad, output frequency 1Hz;

4) GNSS receiver setting circle probable error 20m, noise mean square deviation 2m, output frequency 1Hz;

5) the auxiliary poor 10m of initial value error mean square of ground or space-based measuring system relative distance

6) system is respectively to noise mean square deviation initial value 10 ^-5m/s ²;

7) the thrust acceleration is [0.4; 0.4; 0.4] m/s ², be 500th～700s action time;

8) system filter cycle 1s;

Design conditions based on Relative Navigation of the present invention and above-mentioned setting and technical parameter, adopt Matlab software to carry out simulating, verifying, simulation time 1000s.Be relative position and relative velocity evaluated error curve as shown in Figure 5, as seen from the figure, relative position and relative velocity error be the energy Fast Convergent all, and the relative position error all is stabilized in 20m after 100s; The relative velocity error all is converged in 1m/s after 50s, after 130s, all is stabilized in 0.2m/s.

From simulation result, the inventive method can in the situation that provide a relative distance initial value by ground or space-based measuring system are auxiliary, only rely on spaceborne absolute pointing device GNSS receiver and relative measurement equipment CCD optical camera just can realize the high precision Relative Navigation to the intersection of space non-cooperative Target self-determination.

Claims (1)

1. the Relative Navigation to the intersection of space non-cooperative Target self-determination is characterized in that step is as follows:

Step 1: by service star satellite-based CCD camera tracking observation space non-cooperative target, obtain relative sight line elevation angle ε and relative sight line azimuth angle theta;

Step 2: carry the GNSS receiver by the service star service star is carried out absolute fix and obtains the positional information under inertial system, then by this absolute position, carry out geometry recursion acquisition relative distance, recursion formula is:

${{\mathrm{\ρ}}_t}_k=\sqrt{{\mathrm{\ρ}}_{t_{k-1}}^2+{{\left|\right|r_{G\_t_k}-r_{G\_t_{k-1}}\left|\right|}_2}^2-2{{\mathrm{\ρ}}_t}_k{\left|\right|r_{G\_t_k}-r_{G\_t_{k-1}}\left|\right|}_2\cos \mathrm{\α}}$

Wherein,

for t _kconstantly serve the absolute position vector that spaceborne GNSS provides, ‖ ‖ ₂mean 2 norms, α is t _k-1the line of sight i of unit constantly and the angle of tracker self unit displacement vector delta r;

Step 3: take spacecraft relative track movement equation as the navigational state equation, using sight line elevation angle ε, sight line azimuth angle theta and relative distance ρ as the measurement amount, adopt the UKF filtering algorithm to obtain serving relative position and the relative velocity between star and noncooperative target.

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