FULL ENVELOPE MULTIVARIABLE CONTROL LAW SYNTHESIS FOR A HIGH-PERFORMANCE TEST AIRCRAFT

A full envelope multivariable flight control system is developed for t he Variable Stability In-Flight Simulator Test Aircraft (VISTA). Separ ate control laws are designed for the longitudinal and lateral directi onal axes. Output feedback controllers with integral error feedback ar e created using linear quadratic synthesis and simple linear transform ations. Longitudinal stick inputs are used to generate an angle-of-att ack command at low-dynamic pressure and a normal acceleration command at high-dynamic pressure. Lateral stick inputs are used to generate a stability axis roll rate command, and rudder pedal inputs are used to generate a sideslip command. Linear point designs are integrated into a gain schedule to create a full envelope nonlinear control system. Fl ying qualities are evaluated according to military standards and shown to be satisfactory for a wide operating envelope. Classical gain and phase margins and analysis of the structured singular value show robus tness to be acceptable for a wide operating envelope.