Radio-frequency technology and GNC (guidance navigation and control) for formation flying
- Paper number
IAC-06-C1.3.07
- Author
Mr. Roland Frenkiel, Thales Alenia Space, France
- Coauthor
Mr. Christian Mehlen, Thales Alenia Space, France
- Coauthor
Mrs. Estelle Pierre, Thales Alenia Space, France
- Coauthor
Mr. Michel Sghedoni, Thales Alenia Space, France
- Year
2006
- Abstract
In the frame of formation flying missions, some high requirements at GNC level have been identified: the deployment, the collision avoidance included in the Failure Isolation Detection and Recovery mechanism and finally the reconfiguration after a passage in the collision avoidance mode, identified as similar to the deployment. To achieve these, a new kind of on-board sensor is proposed: the RF subsystem. It measures the relative positions between the individual flyers in a full range (i.e. 4p steradians angular and maximum 30 km distance coverage) and is inspired from GPS techniques to deliver two kind of measurements : erroneous but unambiguous ones and precise but ambiguous ones. An additional third kind of measurement is the power received by one Rx antenna on one flyer from one Tx antenna on another flyer, for the first time used in a control purpose. GNC algorithms based on RF sensor have been developed to transit from an initial disordered state, including the collision risk, to a final state where the geometry is close to the nominal one. The advantages of the proposed methods and technology are the on-board autonomy, the robustness and the low required minimum antenna configuration: a maximum of 6 on one of the flyers, but not on all of them. The deployment, the re-configuration and the collision avoidance are achieved through the measurements and treatment of the powers received by each Rx antenna on one flyer, which allow to estimate a direction of the incoming RF signal with a precision of 40 degrees in all the directions, and 25 degrees in a cone of 40 degrees half-aperture around the nominal direction of another flyer, before being filtered. The final geometry acquisition at the precision of the following stage metrology is achieved through solving the ambiguities, hence getting a precise knowledge of the relative position. Regarding bearing angles estimation, a technique has been developed for a two satellites formation with a minimum RF antennas configuration, where classical redundancy based methods cannot be used. It combines alignment and rotation maneuvers realized with a closed loop based on the estimation described above and the attitude sensors measurements. It finally calibrates the major biases, solves the ambiguities and obtains the relative positions of satellites with 1 degree and 1 cm precisions. Some parts of these developments are based on the Darwin hypothesis.
- Abstract document
- Manuscript document
IAC-06-C1.3.07.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.