Attitude Determination Performance Research Articles

Attitude determination studies for the Earth Observation System AM1 (EOS-AM1) mission

The application of Kalman filter-based attitude determination, with simultaneous gyro bias estimation, to the Earth Observation System (EOS) AMI mission with stellar measurements is analyzed. The study examines the predictive capability of covariance analysis as compared with Monte Carlo analysis, showing that thrice the square root of the Kalman filter covariance matrix diagonal is a reasonable prediction for the 99.7% Monte Carlo results, but not of worst-case performance. The study also establishes further insight into the sensitivity of EOS-AMI attitude determination performance to simulated stellar-lunar geometries by comparing Monte Carlo performance predictions using a statistically generated star field (including statistical lunar blockage gaps) with those using a physical model (real star field and lunar and solar ephemerides). This study further demonstrates that, with EOS-AMI parameters, the performance is driven by the sensor noise rather than the gaps in the star field and confirms these conclusions by Monte Carlo assessments of the orbits with short and long star gaps.

Star Pattern Recognition Sensor of the Astro Type

A Star Pattern Recognition Sensor (SPRS) system has been designed for autonomous, all stellar attitude determination. The system consists of three optical heads, including the CCD camera, three image processors and an attitude determination processor. The first system, the ASTRO 1, was realized from 1984 to 1987 and launched in November 1989 to the Russian MlR space station. This paper will present in-orbit test results. Currently, the advanced ASTRO IM system is under development. First tests with the engineering model have been done. The accuracy of the centroid calculation for a single star has been investigated under laboratory conditions. It was found to vary from 3 to 7 arcseconds, depending on track rates. Performance of attitude determination has been tested using real stars. Under the conditions of constant Earth motion an accuracy of about 2 arcsec was obtained.