Abstract
When the deep space vehicles operate near or above the altitude of the Global Navigation Satellite System (GNSS) in the space service volume (SSV), the number of visible GNSS satellites becomes insufficient for the GNSS positioning, which leads to the divergence in navigation solution and significantly limits the GNSS applications in SSV. To overcome the issue, this article proposes a constraint navigation filter (CNF) with an orbital dynamics model as a constraint to force the deficient GNSS measurement away from divergence. In the CNF design, a simple orbit propagator (OP) is combined with the GNSS measurements in a tightly coupled integration mode by considering the computational complexity and positioning accuracy. The CNF is implemented as a sequential iteration manner to cope with arbitrary GNSS measurement variations. To testify the performance of the CNF design, the simulation is conducted via a self-developed SSV simulation platform. Two typical SSV scenarios in medium and high orbital plane with GPS and BDS measurements, i.e., medium earth orbit (MEO) and highly-inclined elliptical orbit (HEO) are generated, analyzed and compared respectively. The iterative filter gains as well as the positioning errors are investigated. The simulation results show that the typical GNSS positioning results will diverge with time when the visible GNSS satellites are less than 4, while the proposed CNF method can provide stable navigation solutions even there is only 1 GNSS satellite measurement available.
Published Version
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