Precision aircraft attitude determination with multi-antennae GPS receivers

Abstract

Attitude determination is a central problem to aircraft navigation for a wide variety of applications, i.e. airborne laser scanning, airborne gravimetry etc. Standard multi-antennae attitude determination, relying on typically four antennae, provides an attitude accuracy of about 0.1°–0.3° per epoch, where usual update rates are of the order of 5–10 /s; while the noise is quite big, the stability with time is excellent. However, phase centre, multi path and antennae near field effects may cause significant biases or slowly varying effects. On the other hand, gyros may provide attitude information at very high sampling rates and at significantly higher resolutions, however, most are prone to significant drift effects, except e.g., laser gyros of highest precision. For an optimal configuration in economical, operational and accuracy aspects, it is worth to invest also in an advanced multi-antennae GNSS receiver. On these grounds, we acquired a GNATTI antennae receiver of Geo++ company, assembled of typically eight single L1-receivers. The redundancy of this set allows to do an antenna calibration for antennae phase centre, near field, and multipath effects. We did a number of tests both at a test stand and also with an aircraft with various receivers. The paper discusses some details and test results.