Adaptive Control of Multi-Input Aeroelastic System with Constrained Inputs

Abstract

The development of an adaptive control system for the control of an uncertain aeroelastic system, in the presence of constraints on the leading- and trailing-edge control surface deflections, is the subject of this paper. The model describes the nonlinear plunge and pitch dynamics of a prototypical wing section. The open-loop system exhibits limit-cycle oscillations beyond a critical freestream velocity. It is assumed that all the system parameters, except the signs of principal minors of the high-frequency gain matrix, are unknown, and external disturbance inputs are present. The objective is to design a saturating control system for suppressing the limit-cycle oscillations. An adaptive control system is designed for tracking reference pitch angle and plunge displacement trajectories. For avoiding singularity in the adaptive law, a decomposition of the input matrix is used for the design. For the analysis of the effect of input saturation, an auxiliary dynamic system is introduced. By the Lyapunov stability analysis, it is shown that the trajectories of the closed-loop system are uniformly ultimately bounded. Simulation results are presented that show suppression of oscillatory responses despite symmetric and nonsymmetric input constraints, uncertainties in the system parameters, and wind gust.