Adaptive Second-Order Disturbance Observer-Based 3D Integrated Guidance and Control Design Using Fully Actuated System Approach

This paper proposes an Adaptive Second-Order Disturbance Observer (ASoDO)-based 3D Integrated Guidance and Control (IGC) scheme based on the High-Order Fully Actuated System (HOFAS) approach. Firstly, strict-feedback nonlinear IGC model is constructed using the HOFAS approach, simplifying the control command design process. Then, an ASoDO is developed to achieve accurate estimation and feedforward compensation of unknown disturbances, while the adaptive mechanism removes the reliance on disturbance bounds. Finally, a backstepping-based controller is designed to ensure accurate target interception under impact angle constraints, with system parameters tuned to balance convergence speed and control effort. Simulation results validate the effectiveness and robustness of the proposed method.