Reduced-order modeling and controller design for a high-performance helicopter

This paper will discuss the use of balanced coordinates for obtaining a reduced-order model and eigenspace assignment techniques for designing a controller for use in precise hover for handling qualities enhancement of a modern attack helicopter. The reduced-order model requires approximately one-third of the number of states of the original model with an additive error norm upper bound of 0.35. Desired transient response characteristics are achieved through eigenvalue assignment and modal decoupling through eigenvector shaping. Loop-transfer recovery techniques are used for the design of a state observer. Stability robustness of the controller is demonstrated using singular-value techniques.