Active Fault-Tolerant Control for Uncertain Nonlinear Systems: A Decoupling Approach.

Area of Science:

• Control Systems Engineering
• Nonlinear System Analysis
• Fault Diagnosis and Tolerance

Background:

• Implementing active fault-tolerant control (AFTC) is challenging due to coupled observer and controller designs in nonlinear systems.
• The separation principle (SP) is difficult to apply when disturbances or nonlinearities link observer and controller dynamics.

Purpose of the Study:

• To propose a novel AFTC framework for uncertain nonlinear systems that decouples observer and controller design.
• To restore the applicability of the separation principle (SP) in AFTC design for these systems.

Main Methods:

• Developed an observer for fault diagnosis and state estimation, guaranteeing bounded estimation errors.
• Designed an adaptive active fault-tolerant controller for fault accommodation using estimated fault information.
• Treated estimation errors and disturbances as new disturbances, using adaptive updating terms for compensation.

Main Results:

• Successfully decoupled observer and controller designs in the proposed AFTC framework.
• Ensured boundedness of all signals within the closed-loop active fault-tolerant control system (AFTCS).
• Achieved convergence of output tracking error to a small neighborhood around zero.

Conclusions:

• The proposed AFTC framework effectively addresses challenges in nonlinear systems with coupled dynamics.
• The decoupling strategy enables the use of the separation principle (SP) for robust fault accommodation.
• The method demonstrates stability and performance through simulation, validating its practical applicability.