Mesbahi, MehranKashyap, Shavy2025-10-022025-10-022025-10-022025Kashyap_washington_0250O_28802.pdfhttps://hdl.handle.net/1773/53892Thesis (Master's)--University of Washington, 2025Spacecraft attitude control is critical for mission success in communication, navigation, and payload safety, requiring maneuvers that respect complex geometric and hardware constraints. Classical quaternion-based PD/PID controllers provide robust unconstrained attitude regulation but lack systematic enforcement of constraints such as sun-avoidance zones and actuator saturation limits. This thesis presents a hybrid control framework that leverages semi-definite programming (SDP) to generate constraint-compliant, globally optimal attitude trajectories offline, integrating keep-in/out cones and actuator bounds via linear matrix inequalities (LMIs). A quaternion-feedback PD regulator then robustly tracks these trajectories in real time, enabling efficient onboard implementation. MATLAB and Simulink simulations demonstrate that the proposed SDP-guided control outperforms classical PD/PID methods by rigorously respecting all constraints and improving maneuver safety and accuracy. The results suggest strong potential for future small-satellite missions requiring high-performance constrained attitude control.application/pdfen-USCC BYConvex OptimizationLinear Matrix Inequalities (LMIs)QuaternionsSemi-Definite ProgrammingSpacecraft Attitude ControlTrajectory OptimizationAerospace engineeringEngineeringAeronautics and astronauticsThesis