Robust Snapshot Positioning in Multi-Antenna Systems for Inland Water Applications

Abstract

Abstract: Global Navigation Satellite Systems (GNSS) are increasingly used as the main source of Positioning, Navigation and Timing (PNT) information for inland water navigation. Therefore, it becomes of crucial importance to ensure reliability and accuracy of the GNSS-based navigation solution for challenging inland waterway environments like locks or bridges where effects such as multipath and non-line-of-sight (NLOS) can occur. This work extends the single-antenna snapshot positioning solver to a multi-antenna snapshot positioning and orientation solver. In contrast to a single position calculation for each individual antenna, this combined approach allows position and orientation calculation even in the case that each antenna has less than four observations. Any additional observation can be used in a robust estimation framework, for instance by applying the S-estimator, to lessen the impact of NLOS effects. Moreover, different weighting options for the satellite signals are considered where the elevation angle of the satellites, as well as the signal-to-noise ratio measured by the receiver, is taken into account. The presented scheme is evaluated using real measurement data from an inland water scenario with multiple bridges and a waterway lock. With regard to single-antenna algorithms the initial results are encouraging and clearly indicate the advantage of the combined position and orientation calculation with multiple GNSS antennas, especially in scenarios where direct GNSS signals are obstructed. Also the multi-antenna scheme in combination with a robust estimation framework shows the potential to be used in advanced driver assistance systems for integrated navigation as well as autonomous shipping. Why of interest? Well-known robust methods such as the S-estimator can easily be applied to this scheme and in such further help with NLOS as well as multipath effects. This allows for reliable driver assistance systems which are of utmost importance since the majority of inland water accidents are caused by human faults. Therefore, the need for robust navigation schemes such as this is as high as it has ever been.