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
Synchronization of sound generated in binaural hearing system
Methods and compositions to treat and detect misfolded-SOD1 mediated diseases
Vehicle motion control device
Radio link monitoring (RLM) and reference signal received power (RSRP) measurement for heterogeneous networks
Graphical communication user interface with graphical position user input mechanism for selecting a display image
Reoccuring keying system
Method and device for managing subscriber connection
  Randomly Featured Patents
Folding device for male child urination
Oxidative coupling of alkylphenols, alkoxyphenols and naphthols catalyzed by metal complexes of amino carboxylic and amino sulfonic acids
Wireless communication system and wireless communication apparatus
Substituted aminothienopyridines, pharmaceutical composition and use
Collapsible shrimp trawl
System and method for staging concurrent accesses to a memory address location via a single port using a high speed sampling clock
Color graphic image processing system involving data compression using reference samples
User interface for a timer