State-space nonlinear identification and tracking control of aircraft: a motion control problem

Results in motion control for advanced aircraft are developed by solving the nonlinear identification problem and by designing tracking controllers using the complete nonlinear highly coupled longitudinal and lateral aerodynamics. To identify the unknown parameters, we begin by describing the aerodynamics by using a complete model. This model is derived using the Lagrange equations of motion in the form of nonlinear highly coupled differential equations. The identification results presented show that the system order limit does not exist when the reported identification method is applied, and the computational requirements are significantly relaxed. The validity of the results depends upon the aircraft model used, the accuracy of identification, and design versatility. To avoid computational conservatism in the constrained optimization of open-loop unstable multivariable systems, we perform the design using a generalized nonquadratic cost. The unknown parameters for the augmented longitudinal and lateral dynamics of an advanced fighter, which is described by the ninth-order nonlinear differential equations, are identified. Using the aircraft parameters identified, the tracking control problem is solved, and an integral control law is designed. The importance of the integrated identification-control concept reported is that flying and handling qualities, vehicle performances, maneuverability and controllability, agility and survivability of advanced aircraft are significantly improved through the full conventional flight envelope.