Bo-Kyung Jung

Lyapunov-based impact time control guidance laws against stationary targets

Nonlinear guidance laws that consider impact time constraints are proposed. Two-dimensional and three-dimensional impact time control guidance laws are derived using Lyapunov stability theory. Under the consideration of the nonlinear kinematics, it is shown that the missile states converge to the desired equilibrium point by the Lyapunov stability theory. The singularity issue of the proposed guidance laws is also analyzed. Numerical simulations are performed to verify the performance of the proposed guidance laws.

Multiple Model Adaptive Control Scheme for Nonlinear Reconfigurable System

In this study, adaptive control methodology using multiple models is proposed to design a reconfigurable controller for nonlinear systems. An adaptive model and fixed parameter models are used for mode switching, and a re-initialized adaptive model is considered. The conventional mode switching method based on multiple model adaptive control does not guarantee the stability of the closed-loop system. To improve the adaptiveness of a nonlinear system while maintaining the stability, mode switching scheme is modified and a new decision logic is considered. In the mode switching control scheme, forgetting factor and adaptive time concepts are introduced based on the selected model for reconfiguration. An error threshold value is used in the decision logic. Numerical simulation results for a nonlinear discrete-time system verify the effectiveness of the proposed method

ADAPTIVE RECONFIGURABLE FLIGHT CONTROL SYSTEM USING MULTIPLE MODEL MODE SWITCHING

Abstract An adaptive reconfigurable flight control system using the mode switching of multiple models is studied. The conventional mode switching method may not guarantee the stability and the performance of the system. In this study, modified adaptive mode switching and decision logic are proposed to improve the adaptiveness of the transient dynamics of a system while maintaining the stability of the closed-loop system in the overall flight envelope. Fixed parameter models and adaptive models are used for mode switching, and a re-initialized adaptive model is also considered. Proper fixed system models are determined by considering various flight conditions with possible aircraft fault models. The mode switching control system is designed based on the selected models for reconfiguration. Numerical simulations are performed to validate the effectiveness of the proposed method.

NONLINEAR RECONFIGURABLE FLIGHT CONTROL SYSTEM USING MULTIPLE MODEL ADAPTIVE CONTROL

Abstract In this study, adaptive control methodology using multiple models is proposed to design a reconfigurable controller for nonlinear systems. An adaptive model and fixed parameter models are used for mode switching, and a re-initialized adaptive model is considered. The conventional mode switching method based on multiple model adaptive control does not guarantee the stability of the closed-loop system. To improve the adaptiveness of a nonlinear system while maintaining the stability, mode switching scheme is modified and a new decision logic is considered. In the mode switching control scheme, forgetting factor and adaptive time concepts are introduced based on the selected model for reconfiguration. An error threshold value is used in the decision logic. Numerical simulation is performed for a nonlinear discrete-time MIMO aircraft system to verify the effectiveness of the proposed method.