Speaker
Mr
Riccardo Benvenuto
(Politecnico di Milano)
Description
Active debris removal and satellite servicing are some of the current hot spots in space research: plenty of engineering challenges, they deal with fully or partially uncooperative orbiting objects to be approached and captured autonomously by another space vehicle. The Active Debris Removal (ADR) topic focuses on trading-off, designing and making operational mechanisms placed on board an active chaser that can rendezvous with and grapple an inert and tumbling target, to eventually change its dynamics transferring it to a disposal orbit. On the other hand, satellite servicing (SS) deals with refuelling and/or maintenance of active spacecraft, and therefore supposed to be partially cooperating, to be approached and docked by the active chaser to carry out the needed operations when connected. To perform these tasks, different techniques are currently being proposed in literature, starting from the robotic arm to grasp the target to tethered nets/tentacles to wrap it. From dynamics point view, these technologies differ for the flexibility involved in different elements and connections. A general-purpose system design should effectively intervene on objects different in configuration, materials and possibly in dimensions.
ADR and SS tasks define new challenges for Guidance, Navigation and Control (GNC): these missions cannot be tele-operated and ground-controlled due to communications delays, intermittence, and limited bandwidth between the ground and the chaser. Therefore, there is substantial interest in performing these operations autonomously: the research work, here presented, moves in that direction and have the main objectives of
• developing reliable and validated dynamics models, to drive ADR and SS systems design and support GNC implementation, including the flexibility modelling and contact dynamics of capture mechanisms and coupled stacks configurations;
• implementing GNC laws adapted to perform the involved operations, from approaching to removal\servicing, to demonstrate mission feasibility and increase the level of autonomy;
• validating dynamics models and control laws through experimental activities, including microgravity campaigns and hardware-in-the-loop testing.
A multi-body dynamics simulation tool was developed in house at Politecnico di Milano – Department of Aerospace Science and Technologies, fully integrated in Matlab/Simulink and suited to design guidance and control laws: it provides a fast and accurate simulation environment to describe multiple bodies’ six degrees of freedom dynamics, possibly linked by different flexible/rigid connections and including flexible appendages, propellant sloshing and a detailed environmental model to account for all the relevant perturbations, especially at low altitudes. An upgrade of the abovementioned simulator was also implemented to describe the deployment and wrapping dynamics of flexible nets around targets, with the inclusion of collision detection and contact dynamics algorithms. A parabolic flight campaign was successfully performed to validate both flexible dynamics and contact dynamics models: the net 3D trajectory was reconstructed using stereovision (an ad hoc Matlab software was implemented to this end).
In the paper, the abovementioned multibody dynamics tools, their validation process and preliminary simulation output are presented, for both rigid and flexible techniques."
| Applicant type | First author |
|---|
Primary author
Mr
Riccardo Benvenuto
(Politecnico di Milano)
Co-author
Mrs
Lavagna Michèle
(Politecnico di Milano)
