Terminal Guidance Law for Fixed-wing UAVs Based on STA-SDRE Considering State Constraints

This study proposes a terminal guidance law (STA-SDRE) that combines the Super Twisting Algorithm (STA) with the State-Dependent Riccati Equation (SDRE) approach. The proposed law simultaneously satisfies both the Field of View (FOV) constraint of the seeker and the impact angle constraint, while ensuring robust guidance performance under external disturbances. The effectiveness of the proposed terminal guidance law was demonstrated through Monte-Carlo simulations and flight tests, showing reduced impact angle error and Circular Error Probable (CEP) compared to conventional terminal guidance laws. Furthermore, by integrating the proposed terminal guidance with a mid-course guidance scheme, the overall guidance strategy was validated through flight experiments in realistic operational scenarios, confirming its feasibility for practical implementation.