Develop and maintain navigation and state estimation algorithms, including sensor fusion frameworks (e.g., EKF, UKF, particle filters) integrating IMU, GPS/INS, seeker data, and other sensor modalities to provide high-rate, high-accuracy state estimates throughout the engagement timeline. Develop guidance laws (proportional navigation, augmented PN, optimal guidance) and autopilot designs; implement them in flight software; verify performance and robustness through high-fidelity 6-DOF simulation, Monte Carlo analysis, hardware-in-the-loop testing, and flight test correlation.