EFFECTS OF HIGHER ORDER DYNAMICS ON HELICOPTER FLIGHT CONTROL LAW DESIGN

The main objective of the study is to determine whether higher order dynamics such as rotor and inflow dynamics should be taken into account when designing a flight control system to satisfy handling qualities specifications such as ADS-33C. The control methodologies studied are Linear Quadratic Gaussian (LQG), Eigenstructure Assignment (EA), and H∞. The helicopter is a UH-60 in hover. A representative subset of ADS-33C is used. The results indicate that acceptable controllers can be designed using EA with just a rigid body model of the helicopter, but the control activity is high and the controller is not robust. An H∞ design requires the modeling of higher order dynamics, and generates high order controllers, but the resulting controller is robust, and the control activity is lower. It was not possible to determine a suitable LQG based controller that would satisfy the requirements and provide a Rate Command Attitude Hold response type.