Satellite Attitude Detemination Based On Imaging Payload

With the space mission of the satellite payload attitude accuracy requirementscontinue to increase, satellite attitude determination system increasing accuracy along,and the payload attitude usually obtains from attitude determination system and payloadinstalling matrix. Caused by the presence of installation error, the attitude of payloadcan not be obtained accurately. Although the system installation matrix can bedetermined through the ground calibration, during runtime in orbit the spaceenvironment disturbance like thermal deformation makes installation matrix withtime-varying characteristics. So previous attitude determination algorithm has beenunable to meet the accuracy requirements. In recent years, small satellites,micro-satellites, nano satellites developed rapidly with reducing volume and weight tothe development of low-cost and commercial. But the increasing demand for smallsatellite missions for attitude measurement accuracy is also rising. Star camerasrepresent a well-known class of attitude determination sensors. At this time, theyachieve excellent accuracy within arc-seconds. However their size, mass, power, andcost make current commercial versions unacceptable for use on small or micro satellites.With the development of high-speed onboard computer, real-time image processingcomputation is no longer the bottleneck. Therefore, attitude determination obtained bythe image information from the imaging payload itself is very important. The use ofimage-based satellite attitude determination belongs to spacecraft autonomousnavigation, and it’s the future trend of development of autonomous navigation. Itsadvantage is to reduce ground-based monitoring and communication costs, lowersatellite costs and improve satellite survivability and increase satellite missionflexibility.This paper studies the attitude determination methods by the use of camera carriedby remote sensing satellites, the main contents are as follows:First, the Euler angles, quaternion, Euler axis angle and direction cosine matrixcharacteristics and relationships are described and summarized systematically, and smallangle view camera measurement geometry model is derived. And for the earth orientedmode of remote sensing measurement characteristic, the relationship between eachpixel’s output signal of CCD sensor and the earth surface radiation intensity distributionand camera structural characteristics is derived. In addition, the transformationrelationships between the change of satellite orbit, attitude and ground region on theimage plane of the camera is derived and linearized. And the feasibility andprerequisites of attitude determination based on imaging payload are analyzed. Then, for the satellite attitude determination problem with reference landmarks orstar-marks, nonlinear filtering attitude determination methods based on specialorthogonal group SO (3) is designed which focus on incomplete information such assingle vector attitude determination. Multi-vector attitude determination algorithm isdescribed; single landmark attitude determination method is designed for earth-orientedsatellite which equipped with a small angle view camera and discuss its feasibility.Afterwards, composite single landmark attitude determination method is developed, toimprove the accuracy and convergence, and a novel landmarks distribution strategy issuggested; for the tumbling state satellite, attitude determination method based on singleastrometry reference vector is designed which can provide attitude after satellite rocketseparation. Several single reference point methods’ accuracy, stability comparison isgiven. The results show that these methods can achieve a relatively high precision evenif attitude measurement information is incomplete.Finally, for orientation earth satellite with no landmarks, an attitude propagationmethod based on a series of overlapped earth’s surface images using SURF imagematching algorithm is designed. It can calculate the three axis attitude at the exposuretime, also relieve the ground from the need to costly identify landmarks in everypayload image. And, when satellite working in earth-oriented and other sensitivedevices (such as star sensors) unavailable, the attitude can be calculated to improvereliability and extend the whole life of the satellite in orbit. Simulation results show thatdifferent earth’s surface characteristics, orbital altitude and light conditions have greatimpact on attitude determination accuracy: the accuracy of low-orbit remote sensingsatellite and daytime lighting conditions is higher, while high orbit imaging satellites isinappropriate to use this method, also when the imaging area is too flat, it’sinappropriate either.