Attitude sensor calibration using scalar observations
Abstract
A general approach to the inflight calibration of attitude sensors using scalar observations is described. The calibration method does not require attitude computation or modeling and thus places minimal restrictions on the data geometry and collection intervals. The data need not be contiguous and may span days or weeks. Calibration models are derived for spinning, nonspinning, and gimbaled attitude sensors. Ephemeris errors are considered explicitly and shown to limit calibration accuracy. The approach is applied to a conceptual spacecraft which has an earth sensor, spinning sun sensor, fixed-head star tracker, and a gimbaled communication's link with a second spacecraft in a lower orbit. For the example, using 24 hours of sensor data, most calibration errors were reduced to a value consistent with the ephemeris errors, about 0.01 deg. Larger calibration errors for the gimbaled antenna and star tracker pitch angles are attributed to strong correlations and poor observability, respectively. The attitude data were used to solve for calibration and ephemeris state parameters simultaneously, but the calibration accuracy was not improved significantly. Excellent agreement between Monte Carlo and covariance analyses was obtained.
- Publication:
-
Journal of the Astronautical Sciences
- Pub Date:
- June 1990
- Bibcode:
- 1990JAnSc..38..201L
- Keywords:
-
- Attitude Indicators;
- Calibrating;
- Earth Observations (From Space);
- Scalars;
- Star Trackers;
- Attitude Control;
- Covariance;
- Monte Carlo Method;
- Satellite-To-Satellite Tracking;
- Spacecraft Instrumentation