Comparison of Inverse Optimal and Tuning Functions Designs for Adaptive Missile Control

Abstract

An inverse optimal adaptive backstepping technique is applied to the design of a pitch control law for a generic surface-to-air nonlinear missile model, which is aerodynamically controlled. The control objective is to track a commanded reference signal with the angle of attack in the presence of control surface damage and aerodynamic uncertainties. The nonlinear adaptive control law is designed using a control Lyapunov function, after which inverse optimality with respect to a meaningful cost functional is demonstrated. The dynamic parameter update laws of the controller have been augmented with e-modification terms and dead-zones to prevent parameter drift. A second pitch control law is designed by means of the well known tuning functions adaptive backstepping technique. Both control laws are evaluated using numerical simulations where several cases of uncertainty are considered, after which a comparison of their nominal and robust performance is made.