Speaker
Mr
Francesco Torre
(University of Strathclyde)
Description
This work presents the general architecture and capabilities of the ATHENA software package. ATHENA is a toolbox for uncertainty propagation, gudance, navigation and control of single and multiple spacecraft with distributed architecture. ATHENA implements advanced state estimation and filtering techniques and a high fidelity dynamical model. ATHENA allows for the analysis of the coupled orbital and attitude dynamics during close proximity operations and docking with cooperative and non cooperative targets.
The toolbox implements high fidelity models for both asteroids and Earth orbiting objects. The dynamic model includes third body effects, solar radiation pressure and the irregular gravity field of Earth, Moon and asteroids. The toolbox includes spherical harmonics gravity models, tetrahedral models from radar observations, and finite volume models. In the first case, the harmonic coefficients are from actual data or are calculated from the inertia matrix of a user-defined ellipsoid; in the last case, the gravity field is reconstructed from point masses. Given an initial distribution of point masses of arbitrary value contained within the original shape, their position and mass is optimised in order to match the original centre of mass and moments of inertia.
ATHENA allows for the design and analysis of multi-sensor fault tollerant autonomous navigation systems with sensor fusion across multiple platforms with resource sharing. The paper will present an example of autonomous navigation of a formation of spacecraft flying in the proximity of an asteroid. Multiple measurements collected by on-board cameras, attitude sensors and LIDAR are data fused to estimate the state of each spacecraft with respect to the asteroid. Inter-spacecraft links are used to combine measurements and improve resilience and accuracy. It will be shown that different combinations of measurements can be constructed to improve the navigation performance. The overall effect is a system more robust in the presence of failures.
ATHENA includes models of binary systems and the coupled orbital and rotational motion of the two bodies around their centre of mass. The paper will present and example of navigation and control of a single spacecraft placed at a stable libration point.
The toolbox can simulate close proximity operations and autonomous rendezvous and docking (R\&D) with non-coopeative targets on elliptical orbits. In particular, ATHENA can generate optimal scheduled plans and control profiles to rendezvous with multiple targets or to dock multiple spacecraft with a single target. This capability will be shown within an orbit servicing scenario. In this demonstration scenario, the target spacecraft is formed by a set of active payload modules (APM) connected to the spacecraft bus via a standardized interface. ATHENA generates a plan and corresponding guidance for a swarm of small satellites that collaborative (as a colony) re-configure the target spacecraft by removing and replacing APMs.
| Applicant type | Co-author |
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Primary authors
Mr
Francesco Torre
(University of Strathclyde)
Mr
Juan Romero Martin
(University of Strarthclyde)
Prof.
Massimiliano Vasile
(University of Strathclyde)
Mr
Massimo Vetrisano
(University of Strathclyde)
