Adaptive Control With Input Constraints For UAV Flight Application

Fixed-wing Unmanned Armed Vehicles (UAV) have saturation characteristics owing tophysical property of actuators. During the flight, especially in the war or accident, actuatorsare destroyed, at the same time, restrained by saturation, admirable performance cannot beachieved, or even flight control may fail. Thus, fixed-wing UAV dynamics with inputconstraints have been explored for robust and adaptive control. Main contributions of thework are as follows:At first, the principle of fixed-UAV flight is analyzed. Based on nonlinear system,mathematic dynamics are built and linearized. Parametric uncertainties are also defined tolay foundation for further control algorithm.Then, flight controller is designed with parametric uncertainties. There are two parts:one is adaptive control without input constraints and the other is combination of μ-modadaptive control with input constraints, which assures UAV tracks command signals underboth normal and special conditions, meanwhile, arrives at desirable transient performanceand stability. In addition, use of Bounded Gain Forgetting (BGF) facilitates fasterconvergence of parameter estimation. Moreover, improvement of projection operationbased on basic adaptive controller is employed to assure robustness.At last, the stability of the closed-loop system can be guaranteed by using Lyapunovtheory. The merits and effectiveness of the proposed method are illustrated by numericalexamples of the longitudinal and lateral dynamical systems of a fixed-wing airplane.