GNSS-based attitude determination for remote sensing platforms

Abstract

Global Navigation Satellite Systems (GNSS)-based attitude determination is a valuable technique for the estimation of platform orientation. Precise attitude determination using multiple GNSS receivers/antennas mounted on a remote sensing platform relies on successful resolution of the carrier phase integer ambiguities. The LAMBDA method has proven to be an efficient method to solve integer least squares problems. This method is, however, only applicable to unconstrained and/or linearly constrained models, but not to quadratically constrained models such as the GNSS attitude model. For a set of GNSS antennas rigidly mounted on a platform, a number of nonlinear geometrical constraints can be exploited for the purpose of strengthening the underlying observation model and subsequently improving the capacity of fixing the correct set of integer ambiguities. In this contribution, we describe and test the Multivariate Constrained (MC-) LAMBDA method, which effectively makes use of the known antenna geometry. Reliable and instantaneous integer estimation is particularly a challenge for single-frequency applications with low cost GNSS receivers. With our field tests, we show the potential of stand-alone, unaided, single-frequency, single epoch attitude determination.