ETD

• 6-DOF dynamics
• extended Kalman filter
• extended state observer
• inertial measurement unit
• Kalman filter
• MATLAB/Simulink
• multi-rate simulation
• Pierson-Moskowitz spectrum
• radar altimeter
• sea-skimming missiles
• sensor error modelling
• state estimation
• vertical guidance
• wave-disturbance rejection

This thesis investigates wave-disturbance rejection in the vertical guidance channel of sea skimming missiles, with an emphasis on realistic sensing and end to end validation of state estimation strategies. The work, carried out in collaboration with MBDA Missile Systems, designs and evaluates three estimator families: the Kalman Filter (KF), the Extended Kalman Filter (EKF), and a hybrid Kalman–Extended State Observer. These estimators are aimed at mitigating sea wave corruption of radar altimeter measurements while preserving guidance performance under practical discrete time execution constraints. A MATLAB/Simulink framework was developed to model sea wave disturbances (single tone excitations and Pierson–Moskowitz realizations representative of NATO sea states) and non ideal sensors, including a radar altimeter and tri axial IMU accelerometers with dominant error sources modelled. Validation was performed through a staged campaign: a simplified vertical channel benchmark to isolate mechanisms and tune filters, followed by a high fidelity 6 DOF platform to assess performance under nonlinear couplings and multi axis manoeuvres. Results show that estimator augmentation substantially reduces altitude tracking error during sea skimming and clarifies trade offs between oscillation attenuation and steady state offsets in high fidelity conditions, supporting the adoption of model based estimation and disturbance observer concepts for robust future sea skimming guidance systems.