Design of a Helicopter Stability and Control Augmentation System Using Optimal Control Theory.

The report presents the design of a helicopter stability and control augmentation system using optimal control techniques. The helicopter used as an example was the Sikorsky H-53, but the design procedure is applicable to other helicopters as well. Only the longitudinal dynamics are considered. A technique is described for the design of multivariable feedback controllers based upon results in optimal control theory. For a specified performance index the feedback controller is obtained by solving the matrix Riccati equation. A model is used in the forward controller such that the response of the model to pilot inputs approximates the desired helicopter response. A fixed gain controller is obtained which may be used over the entire helicopter flight envelope. The results show that optimal control theory can be used to design a helicopter stability and control augmentation system. Responses obtained may be classified as those which are desirable and yield good handling qualities. Author