In a sun-heading determination scenario, coarse sun sensors (CSSs) can be paired with rate gyroscopes in order to estimate sun-line direction and rotation rate. Relying solely on CSS measurements for sun-heading and spacecraft rotation rate estimations is advantageous in scenarios where reliance on the fewest number of devices is desired. Here, the challenge is to find a robust method for heading determination relying neither on rate gyroscopes nor on spacecraft dynamics. In such a scenario, the rotation rate of the spacecraft is estimated in order to provide state derivative control or simply for better sun-heading estimation. A novel sun-heading filter is derived that estimates only the observable components of the body-rate vector as the rate about the sun-heading axis remains unobservable. Elegantly switching between kinematic formulations to avoid singularities of one description, it provides not only better sun-heading estimates but also a partial body-rate estimate. The new filter is compared to two filters for gyroscopes-less sun-heading estimation. One comparison filter uses a projection method to remove the unobservable rate component, and another comparison filter uses numerical heading differences to estimate a rotation rate. The filters vary in state vectors, kinematics, and filter types, with the goal of controlling or removing nonobservability.
Removing Rate Unobservability in Sun-Heading Filters Without Rate Gyroscopes
Journal of Spacecraft and Rockets ; 57 , 5 ; 918-929
2020-04-22
12 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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