Attitude Determination and Relative Positioning for LEO Satellites Using Arrays of GNSS Sensors

Global Navigation Satellite Systems (GNSS) have become ubiquitous in positioning, guidance and navigation. GNSS-based attitude determination and relative navigation are the important and promising applications. In this contribution we explore the potential of Low Earth Orbiting (LEO) satellite navigation in formation using arrays of GNSS sensors. We consider multiple LEO platforms in close formation, each equipped with multiple GNSS antennas/receivers. Platform processing involves precise attitude determination using the Multivariate Constrained Least-squares AMBiguity Decorrelation Adjustment (MC-LAMBDA) method effectively utilizing known antenna geometry in local body frame. Between-platform processing involves estimation of unconstrained baselines between platforms using array-aided relative positioning effectively exploiting the platform antenna geometry in improving between-platform ambiguity resolution and baseline estimates. Finally, we use nonlinear recursive filtering to further improve the attitude angular estimates and between-platform baseline estimates. Our hardware-in-the-loop experiment with space enabled Namuru GNSS receivers shows the potential of stand-alone, unaided, single-frequency attitude determination and relative positioning of LEO satellites.