Quadrotor flying robots, valued for their VTOL capability, agility, and compact design, underpin diverse missions like aerial photography, delivery, and search-and-rescue. Stable flight hinges on precise attitude estimation—tracking roll, pitch, and yaw—where inertial navigation systems (INS), relying on inertial measurement units (IMUs) with gyroscopes and accelerometers, play a central role. Yet, raw IMU data faces critical limitations: gyroscopes drift over time due to bias/noise, while accelerometers conflate linear motion with gravity, degrading accuracy during dynamic maneuvers or prolonged operation. Thus, robust inertial attitude solutions are pivotal for quadrotor autonomy.