Scheduled smooth MIMO robust control of aircraft verified through blade element SIL testing

This paper demonstrates a multi-input multi-output (MIMO) robust control approach where multiple scheduled designs are merged to produce a smooth control law. The design is verified using software-in-the-loop (SIL) testing based on blade element theory (BET) for highly realistic flight simulations. An inner-loop attitude controller balances performance and robustness, achieving a fast response time, low overshoot, good noise rejection and minimal lateral-longitudinal coupling. The controllers are formed at several predetermined grid points so the design covers a wide flight envelope. Blade element SIL testing shows that the flight control system preserves stable flight and follows the references well, even under tough weather conditions. The proposed strategy is also compared with a classical autopilot design procedure and is seen to be superior.