Tethered Interferometric Constellations with Self-Stabilizing Platforms’ Attitude Control
- Paper number
IAC-05-C1.3.10
- Author
Prof. Carlo Menon, Simon Fraser University, Canada
- Coauthor
Mr. Claudio Bombardelli, University of Padova, Italy
- Coauthor
Prof. GianAndrea Bianchini, University of Padova, Italy
- Year
2005
- Abstract
International space agencies envision future space missions involving formation flying of multiple separated spacecraft acting collaboratively as a single unit for a specific task. Often, not only the relative positions of the individual spacecraft need to be accurately controlled but also their attitude, as in the case of space interferometry applications where the individual platforms need to be accurately pointed towards the same inertial target while keeping a precise relative attitude for light beam transmission. Such attitude control problem may be particularly compelling, especially for long baseline spaceborne interferometry, where broadband structural vibrations induced by reaction- wheel- and thruster-based control maneuvers can compromise the performance of the interferometric system. Recent studies have shown that long baseline space interferometric formations can be implemented linking the different platforms with long tethers having small diameter and light mass as proposed for the NASA-funded SPECS interferometry mission. Spinning tethered formations have the advantage of a significantly reduced fuel consumption and a simplified control scheme for the position of the individual units based on passive stabilisation. In the framework of dynamics and control of spinning tethered ineterferometers, previous work has been focused on the issue of controlling the position of the individual platform modeled as point masses, while the problem of attitude stabilization of the tethered units has not yet been addressed. This paper investigates and demonstrates the possibility of exploiting the presence of a tether link to stabilize the attitude of the individual platforms modeled as rigid bodies. The stabilization technique is based on a passive damper interface at the tether attachment point which makes the system converge towards a minimum energy configuration where each platform is kept pointed towards an inertial target while spinning around its axis of maximum moment of inertia. In this way each individual spacecraft can maintain a stable inertial pointing without the intervention of specific attitude control actuators. This very simple control scheme has the merit of reducing the complexity of the control architecture and the system resources employed. Moreover, the absence of reaction wheels and thrusters intervention increases the reliability of the system and prevents the excitation of structural vibrations which may compromise the performance of the interferometer. With reference to proposed space interferometric missions a mechanical scheme for the attitude control system is designed and its dynamic performance numerically analyzed. Simulations based on a multibody dynamics computation tool are carried out to evaluate the effectiveness of the control system proposed in both counteracting the effect of environmental perturbations on the pointing stability of each platform and in suppressing residual oscillations caused by maneuvers (such as formation retargeting and reconfiguration). Results show the effectiveness of the proposed control strategy and provide an important element towards the implementation of future space-based observatories based on tether-connected architectures.
- Abstract document
- Manuscript document
IAC-05-C1.3.10.pdf (🔒 authorized access only).
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