The Design and Validation of a Spacecraft Orbit and Attitude Simulation Environment in MATLAB/Simulink

  • Author / Creator
    Robson, Christopher, RJ
  • CubeSats and Aerodynamic Attitude and Orbit Control Systems (AAOCS) orbit in Very Low Earth Orbit (VLEO) where the effect of aerodynamic force and torque is significant. In the mission analysis and design phases of CubeSat missions and satellite missions employing AAOCS, aerodynamic perturbations, along with others, must be modeled accurately. While several software packages from commercial, open-source, and academic sources exist to comprehensively model the orbital and attitude dynamics of satellites, barriers exist to their use by researchers, student groups, and small businesses. To overcome this barrier, OrbSim, an open-source software package, was developed in MATLAB/Simulink to model the orbital and attitude dynamics of spacecraft. This software package models aerodynamic forces and torques using the NRLMSISE-00 atmospheric model and assuming horizontal rotation of the atmosphere. Solar radiation pressure forces and torques are modeled using precise orbit ephemerides for the Sun, and assuming Earth’s shadow is cylindrical. Both the solar radiation pressure and aerodynamic models are attitude and geometry dependent. OrbSim models gravitational forces from a non-uniform Earth using the Earth Gravitational Model 2008 (EGM2008), and gravity from the Sun and the Moon. Additionally, gravity-gradient torque and residual magnetic torque are modeled. The magnetic field is modeled using the International Geomagnetic Reference Field 12 (IGRF-12), and the World Geodetic System 84 (WGS84) is used for the reference ellipsoid. OrbSim was validated through comparison to AGI’s System Tool Kit, an industry standard software package for simulating satellite orbital dynamics. The comparison was completed by simulating, in both STK and OrbSim, a satellite’s orbital trajectory using different permutations of the perturbing forces. A case study predicting the lifetime of The Humanity Star was also completed, demonstrating the potential of OrbSim.

  • Subjects / Keywords
  • Graduation date
    Fall 2018
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
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