First Control System Evaluation of the Research Helicopter FHS

Abstract

The paper presents an active controller to increase stability of the air resonance mode of the Flying Helicopter Simulator, FHS, research helicopter. The air resonance mode on the FHS is particularly excited when roll rate feedback loops are incorporated in the main flight control design. The air resonance controller is designed to operate independent of the main flight control system. Several approaches of the air resonance controller have been developed and optimized in simulation. The simulation environment makes use of system identification models derived from flight test data. The models are specially adapted and tuned for reproducing the air resonance mode. The two most promising air resonance controller concepts are finally flight tested: an adaptive notch filter and a modified cross feed approach. The paper describes the development process, the air resonance controller design and the results of the flight test campaigns.