Radio-frequency sensor fusion for relative navigation of formation flying satellites

The increasing need for robustness, reliability and flexibility of relative navigation systems imposed by the current and future autonomous formation flying missions, calls for the implementation of solutions using an alternative approach to single-sensor systems. These schemes possess different levels of availability, mainly driven by sensor failure and mission orbit profiles. The data obtained from the Global Positioning System (GPS) and Formation Flying RadioFrequency (FFRF) sensors from the nominal phase of the PRISMA mission provide an opportunity for the implementation of an extended approach for the generation of relative navigation solutions. The present study introduces the design of a simple relative navigation filter based on the sensor fusion concept, which makes use of differential GPS and FFRF measurements obtained from the on-board sensors. The filter design uses the Hill-Clohessy-Wiltshire and Yamanaka-Ankersen relative dynamics models as well as numerical integration methods including the J2-perturbation for the state and associated covariance matrix propagation. The design is tested using flight data obtained during representative formation flying operations of the PRISMA mission.