Multiple Model Adaptive Control For Switched Affine System And Its Application To Aero-engines

Aero-engine is a kind of complex system with multi-discipline integration.It is of great difficulty in modeling and control for the aero-engine.Especially when the aero-engine has performance degradation or manufacturing errors,there will be deviation in the system equilibrium point,which leads to the system deviates from the desired trajectory easily.In addition,there are also widespread problems of unmodeled dynamics and multi-mode switching operation for the aero-engine,which also bring extra difficulties and challenges to the controller design.This thesis takes aero-engine as the controlled plant and focuses on solving the problem of asymptotic tracking control under the condition of uncertainty,performance degradation and multi-mode operation of aero-engine.The main work includes the following parts:(1)This thesis regards a practical aero-engine as the controlled plant.First of all,a nonlinear component-level model of the aero-engine is built on the basis of the working mechanism.Then,all component models are iterated jointly and solved under the typical working conditions.At the same time,the steady-state equilibrium is solved.Furthermore,by linearizing the system at the equilibrium point under different working modes and considering the degradation factors,the affine subsystem models can be established.Finally,the subsystems are combined to build a switched affine system for the aero-engine control.(2)Aiming at the affine system,the MMAC method is applied to realize stable and fast state tracking issues.First of all,an adaptive controller with resettable parameters and an adaptive law with projection function is designed.Then,three types of identification models are configured for the system as the parameter set.In the meanwhile,an augmented filter is designed to calculate the unknown parameters of the system in real time,and the calculated real values are reset to the fixed identification model with resettable parameters in the identification model set.Furthermore,a mixed performance index is proposed to select the optimal identification model and reset its parameters to the adaptive controller.Finally,the sufficient condition of asymptotic stability for the closed-loop error system is given and the effectiveness and superiority of the proposed method are verified in the numerical simulation.(3)Aiming at the switched affine system,a two-layer switching structure and switching law are proposed.First of all,in order to solve the subsystem tracking problem,multiple model adaptive control strategy is used to design the inner switching of the subsystems.Then,the changes of the Lyapunov function for the switched system is discussed by analyzing three cases in which the subsystems and the identification models are not switched,only the identification models are switched,both the subsystem and the identification models are switched.Furthermore,the outer affine subsystem switching law that based on average dwell time theory is proposed to ensure the asymptotic tracking performance of the two-layer switched affine system.Finally,the sufficient condition of the asymptotic stability for the closed-loop error system is given and the effectiveness of the proposed method is verified in the numerical simulation.