BDS Autonomous Orbit Determination using Inter-satellite Tracking and Onboard Accelerometers

Abstract

Satellites Autonomous Navigation (AutoNav) mode utilizes inter-satellite crosslink measurements to maintain satellites operation, without relying on ground control facilities. The newly launched BeiDou (BD) satellites are capable of conducting satellite to satellite tracking (SST). However, as there is no absolute reference frame control with SST data only, satellite constellation will experience rotation related to the earth fixed reference frame, due to various force perturbations. The main problem for orbit determination is how to precisely model the non-conservative forces (i.e. Solar Radiation Pressure (SRP)). Space-borne accelerometers have been successfully used for gravity recovery and atmosphere study in GRACE, CHAMP, and GOCE missions to measure the non-conservative forces directly. This study investigates the feasibility to use accelerometers onboard BD satellites to improve BD AutoNav accuracy and service span. Using simulated BD orbits and SST data, AutoNav has been performed using SST data only or SST data with accelerometers. Using the simulated inter-satellite range observations of decimeter level accuracy (?=0.75 m), AutoNav with accelerometer data can achieve 15 m and 8 m horizontal orbit accuracies for GEO/IGSO and MEO satellites within a 180-day AutoNav period, which is significantly better than the results from SST data only.