| This dissertation presents a new approach to designing flight control systems that incorporates a variable rotor speed command into flight control system design. In this new approach, the flight control system, designed in a framework of integrated flight/propulsion control, generates a continuously-variable rotor speed command to the propulsion controller, in addition to conventional flight control commands. The approach offers the potential for improved performance in the regulation loop and/or the outer loop, and offers the potential for automating the outer loop.; Specifically, this dissertation demonstrates the benefits of varying rotor speed for both the regulation loop and the outer loop. For regulation, improved bandwidth and disturbance rejection are obtained in both vertical and yaw motions by designing extended linear controllers that use a variable rotor speed command. For large vertical and yaw maneuvers, reductions in maneuver completion time are obtained with minimum-time control designs. In particular, it is shown that the variable rotor speed command is essential to taking advantage of variable rotor speed in large yaw maneuvers.; The two control problems of small motion regulation and large maneuver automation are addressed by a solution framework that merges a feedback regulator and a feedforward trajectory generator. In designing the regulator and trajectory-generator components, this research develops new control synthesis techniques that are broadly applicable for generating and implementing high-performance controls. An optimal synthesis technique, based on parameter optimization using nonlinear programming, facilitates the regulator design to comply with the handling qualities specification. A learning-based implementation technique of minimum-time control in a model-following framework enables automation of minimum-time maneuvers.; The flight control system consisting of the regulator and trajectory generator is applied in simulation to a UH-60A Black Hawk helicopter and is verified to provide enhanced transient performance and potential for automating an outer control loop. |
