ABSTRACT
This chapter reviews frequency-domain system identification methods for development and integration of aircraft flight control systems. These methods were developed under a long-term research activity at the Ames Research Center by the Army Aeroflightdynamics Directorate, NASA and Sterling Software. System identification provides an accurate, rapid and reliable approach for defining design specifications and for validating aircraft flight performance for highly augmented flight control systems. Near-real-time system identification was employed during the X-29 aircraft flight testing for on-line verification of stability margins in a highly efficient flight envelope expansion program. The flight test program for flight control and handling-qualities validation and optimization has a significant impact on the overall development schedule and cost for modern fly-by-wire aircraft. Modern fly-by-wire aircraft employ high-bandwidth digital flight control systems to achieve greatly increased agility and disturbance rejection across a significantly widened operational flight envelope as compared with the older generation of aircraft.
