Application of discrete proportional plus integral (PI) multivariable design to the control reconfigurable combat aircraft (CRCA)

Multivariable control laws developed by B. Porter (1981) have been used to successfully perform maneuvering tracking tasks with the control reconfigurable combat aircraft (CRCA). Porter´s method was used to design a discrete proportional plus integral (PI) control law. Output and selected state rate feedback were used. The results obtained in the terrain following/terrain-avoidance (TFTA) flight condition showed robust tracking control for the CRCA for five selected maneuvers. Single failures were introduced to test the ability of the fixed-gain design to successfully control the aircraft and perform the maneuvers. Time responses show that the CRCA can be made to successfully perform all five maneuvers for two of the three control surface failures investigated. For high gains, the system transfer function becomes asymptotically diagonal (the outputs are uncoupled). Based on this property, a frequency analysis was performed for each output with respect to its associated input