Helicopter Attitude Command Attitude Hold Using Individual Channel Analysis and Design

A control law was designed for a linearized model of a typical combat rotorcraft trimmed to 30-kn forward flight. Although based on a single flight condition, the same controller is found, in simulation, to give level-one performance for the range of speeds from hover to 80 kn, for handling qualities based on small-amplitude motions. Control synthesis was performed using the method of individual channel analysis and design (ICAD). ICAD is a neoclassical, frequency-domain control analysis and design method for multivariable systems. Its most distinctive feature is the use of multivariable structure functions, which make explicit the role of cross coupling in the design process and on the robustness. The control law so obtained is very simple, and the results suggest that modern control methods, based on optimal synthesis, are not a necessity for the helicopter flight control problem. (Author)