Active damping of satellite nutation
AssigneeMatra
InventorJerome Lievre
Life of this patent
Estimating the term…
Abstract
For controlling nutation of a three-axis stabilized satellite, the angular speed of a solar panel carried by the satellite is selectively and temporarily varied about an average value for modifying the inertia cross-product thereof and generating an angular momentum transverse to the angular momentum present in said body with a phase with respect to the nutation motion which tends to decrease the amplitude of the nutation motion.
Claims7
A process for controlling nutation of a three axis stabilized momentum biased geostationary satellite, comprising the steps of:
- locating at least one solar array on said satellite for rotation about a North-South axis with the center of gravity of said solar array being out of said North-South rotation axis by a predetermined amount;
- measuring the amplitude and phase of satellite nutation;
- and controlling the rotation speed of said solar array for temporarily and selectively modifying said rotation speed with respect to a constant predetermined average value with such a phase with respect to the nutation motion as to reduce the amplitude of nutation by varying the product of inertia represented by said solar array.
In a three axis stabilized momentum biased geostationary satellite having a body, at least a flywheel in said body providing an angular momentum, at least one solar panel connected to said body for rotation about a North-South axis and biased with respect to said North-South axis to exhibit a non zero product of inertia and motor means for rotating said panel about said axis, an apparatus for controlling nutation of said satellite, comprising:
- first means for providing signals representative of yaw and roll movements about satellite axes caused by nutation,
- second means for deriving yaw and roll rates from said signals,
- third means for determining, from said rates, yaw and roll torques to be applied to said satellite body for damping nutation,
- fourth means for computing the torques to be applied about a sun directed axis and an axis orthogonal thereto from said yaw and roll torques and from signals representing the actual angular position of the satellite about the North-South axis,
- and fifth means for determining a depointing angle to be applied to said solar panel for developing said yaw and roll torques.
Dependencies are inferred from the claim text.