Design of Guidance and Control Algorithms for A Vision Based Navigation Rendezvous Mission on Mars Orbit
- Paper number
IAC-05-C1.8.10
- Author
Mr. Emanuele Di Sotto, DEIMOS Engenharia, Portugal
- Coauthor
Mr. Francisco Câmara, DEIMOS Engenharia, Portugal
- Coauthor
Mr. Augusto Caramagno, DEIMOS Space, Spain
- Coauthor
Mr. Salvatore Mancuso, European Space Agency/Headquarters, France
- Coauthor
Dr. Luis F. Penin, DEIMOS Space S.L., Spain
- Year
2005
- Abstract
Technologies for rendezvous and docking (RVD) in Europe have been studied and developed since the early 80s. Nowadays European space industry has reached full maturity in this field resulting in the Automated Transfer Vehicle (ATV) that is scheduled for launch in 2006. A more challenging perspective is represented by the complex RVD operations envisaged for the future exploration missions as the case of "Mars Sample Return". In particular, for this kind of mission, the requirement for an autonomous navigation system becomes mandatory due to the long communications delay with the Earth and the need for real time knowledge of the spacecraft state when carrying out RVD operations. Autonomous navigation requirement is addressed within this paper considering a camera-based sensor in charge of providing measurements of the spacecraft translational and rotational state with respect to the target. These measurements are collected and processed in real time to provide continuous navigation solution on board. It shall be remarked that this camera-based navigation shall be performed from a relatively long distance (i.e. >1 km), in contrast to current systems (i.e. the ATV-VDM which starts at a relatively close distance of 300 m). In first place, the paper will detail tailored guidance and control algorithms derived for the last phases (far closing, closing and final approach) to meet the mission requirements while fulfilling the constraints posed on the overall mission profile by the camera-based sensor. The most important requirement to be met through the guidance and control algorithms is represented by the safety of the system. Nominal trajectories, with the established uncertainties deriving from the navigation accuracy, must be safe. This requirement is implemented considering passive safe trajectories all over in the mission profile. Moreover, camera sensor introduces some important constraints on the reference trajectory design such as (e.g): the need to constantly keep the target within the camera field of view (FOV) and avoid direct sun illumination within the FOV. The former condition poses a strict restriction on the trajectory excursion from V-bar (velocity direction) whereas the latter limits the available time to carry out the specific mission phase. These requirements and constraints lead to design a specific mission profile based on multi-boost hopping strategies being each boost controlled through a dedicated terminal point guidance scheme. The paper will describe in detail the design and application of this terminal guidance. This scheme is in charge of updating the nominal boosts in order to attain the final prescribed position while cancelling any drift component on the resulting path. In other words, this approach allows the chaser to constantly remain onto an elliptical path while reaching the prescribed stand-off point. Such a strategy, derived using the "travelling ellipse" formulation for the relative motion, provides intrinsically safety conditions meeting the major requirement posed on the mission profile. Secondly, attitude and trajectory controllers, synthesised for all the mission phases, will also be presented. These controllers take into account sensor noise and the presence of flexible and sloshing modes, as well as the coupling between position and attitude for the final approach before docking. The paper finally will briefly highlight commonalities and differences wrt to an RF-based approach.
The work presented in this paper was done under the ESA/ESTEC contract for the study of Vision Based Relative Navigation Techniques Framework (VBRNAV) (ESA/ESTEC Contract No. 18038/04/NL/JA)
- Abstract document
- Manuscript document
IAC-05-C1.8.10.pdf (🔒 authorized access only).
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