Enhancing Flight Control System performance using SDRE based controller as an augmentation layer

Shipboard operation of rotorcraft remains an active topic of significant interest to current Naval practice, particularly for the operations of tilt-rotor aircraft (e.g., V-22 Osprey) in close proximity to a surface ship and its resultant airwake. The coupled relationship of the ship and aircraft system for shipboard environment, known as the "dynamic interface" (DI) between two moving objects, during sea-based aircraft launch and recovery operations increase the complexity of the operations and pilot workload beyond the normal land-based operating conditions. The two primary factors that affect rotary-wing aircraft during DI interactions are relative wind-over-deck (incoming wind angle and speed) and ship motion. The wind flowing over the ship structure produces a turbulent airwake. Six-degree-of-freedom (6DOF) motion by the ship results in a variable turbulence source that dramatically complicates rotary-wing aircraft operations. This paper presents an adaptive controller solution using the State Dependent Riccati Equation (SDRE) approach to augment the existing Flight Control System (FCS) to address the DI operating environment. The focus is not to replace the existing aircraft FCS, but rather to augment it with an SDRE controller implemented in a parallel fashion to provide additional compensation to the existing FCS to address the DI operating environment. The proposed concept, via a high fidelity simulation, demonstrates the effectiveness of the SDRE controller implemented in an augmentation fashion (i.e., add-on configuration), thus minimizing flight software change impact and ensuring that there is no risk to an existing aircraft FCS.