Precise GNSS Attitude Determination Based on Antenna Array Processing

Global Navigation Satellite Systems (GNSS)-based attitude determination has been recognized as a significant field of study in numerous ground, marine and airborne applications. This paper investigates the feasibility of precise attitude determination using a GNSS receiver capable of antenna array processing. The ability to determine attitude parameters by employing only a single satellite signal distinguishes this approach from methods based on carrier phase measurements and ambiguity resolution. This is especially important in challenging environments where a limited number of satellites are available. Moreover, this approach has the advantage over other methods by employing an antenna array with short spacing between adjacent antennas (less than half a wavelength), especially where the structural dimension is an important concern such as in small unmanned aerial vehicles (UAV). Herein, a modified version of the recursive least squares (RLS) method is proposed to adaptively estimate each satellite’s steering vector and then the roll, pitch and heading angles of a moving vehicle. The proposed adaptive method is fast and computationally of low complexity and therefore it can properly operate in real time applications. The proposed method is applied to a set of real GPS L1 signals collected using a six-element antenna array to verify its effectiveness and assess its performance. A tactical-grade inertial navigation sensor (INS) is used as reference to evaluate the accuracy of heading estimates in a scenario where the array is mounted on a moving vehicle.