Resources Contact Us Home
Methods for controlling spacecraft attitudes without exciting spacecraft resonances

Image Number 6 for United States Patent #6076772.

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.

  Recently Added Patents
Gas flow indicator
Integrated circuits with magnetic core inductors and methods of fabrications thereof
Method and apparatus for detecting an intermittent path to a storage system
Display stand for a mobile tablet computer
Semiconductor element-embedded wiring substrate
Hand-held electronic display device
Poloxamer foamable pharmaceutical compositions with active agents and/or therapeutic cells and uses
  Randomly Featured Patents
Refrigerator with internal compartment divisible into independent temperature zones
Post and handrail support
Security-transfer systems
Para-substituted phenylene derivatives
Antenna coupler
Filtered connector
Method and apparatus for mixing signals
Phase control switching system
Network swappers and circuits constructed from same
Method of manufacturing a shapeable short-resistant capacitor