GPS Block IIR Non-Conservative Force Modeling: Computation and Implications

摘要: This paper discusses the development of a high precision non-conservative force model for GPS Block IIR spacecraft, carried out at University College London. The computation uses suite newly developed techniques that can incorporate level complexity in spacecraft structural description. modelling approach caters thermal effects due to behaviour multi-layered insulation, and imbalance induced by solar panels during full-phase eclipse seasons. foundation derives from simulating incident photon flux using pixel array. is projected onto computer simulation structure, ray-tracing algorithms are used accurately compute both insolated shadowed parts spacecraft. ray tracing extended reflected radiation striking other causing further acceleration. array be rotated anywhere around spacecraft's circumscribing sphere, within automatically adjusted mimicking attitude control's on orbit behaviour. mathematical physical field seen as limiting factor many applications involving GPS, ranging determination low Earth orbiting through issues real-time realisation global reference frame, which limited accuracy medium navigation satellite trajectories. Specific characteristics presented impact upon modelling, and, hence, prediction. These include seasons yaw rate maneuvers, well potential problems related power draw panels. characteristic these design facets trajectory assessed numerical integration dynamic model. employs an 8th order embedded Runge-Kutta integrator with adaptive step-size control. High gravity coefficients used, generating associated Legendre polynomials numerically stable recursive formulation. International Rotation Service conventions frame transformations. Comparisons made older IIA constellation terms how dynamics could modelled priori, this has prediction determination. technique allows assessment Y-bias uncertainties specific strength forms were previously impossible. study results presented, along discussion implications control design. Mean errors over 12 hour arc models 0.266m height, 0.046m across track 1.171m track.