Methods for controlling spacecraft attitudes without exciting sp

Details Methods for controlling spacecraft attitudes without exciting sp Methods for controlling spacecraft attitudes without exciting sp

1997-12-15

2000-06-20

Barefoot, Galen L.

Aeronautics and astronautics

Spacecraft

Attitude control

244165, 244166, B64G 124

Patent

active

060767723

ABSTRACT:
Attitude-control methods are provided which eliminate or reduce structural resonances in spacecraft that are excited by momentum wheel imperfections. The methods are preferably practiced with an over-determined attitude-control system which is typically available because spacecraft often carry backup momentum wheels to insure against failure of primary momentum wheels. In a method embodiment, a set of angular-velocity waveforms is selected that substantially realizes a commanded momentum vector when applied to a corresponding set of momentum wheels wherein none of the selected angular-velocity waveforms dwells at a resonant frequency of the spacecraft. The angular velocity of the corresponding set of momentum wheels is then conformed to the selected set of angular-velocity waveforms to realize a spacecraft attitude that corresponds to the commanded momentum vector without exciting the resonance. The step of selecting the angular-velocity waveforms can include the steps of offsetting a constant rotational frequency and of adding a velocity modulation to avoid dwelling at the resonant frequency.

REFERENCES:
patent: 3765621 (1973-10-01), Shigehara
patent: 4567564 (1986-01-01), Bittner et al.
patent: 5025381 (1991-06-01), Goodzeit et al.
patent: 5058835 (1991-10-01), Goodzeit et al.
patent: 5816538 (1999-10-01), Challoner et al.
Shigehara, "Geomagnetic Attitude Control of an Axisymmetric Spinning Satellite" Journal of Spacecraft vol. 9 No. 6, pp391-398, Jun. 1972.

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