Control allocation based fault tolerant control of descriptor system with actuator saturation

Area of Science:

• Control Systems Engineering
• Nonlinear Control Theory
• System Dynamics

Background:

• Descriptor systems (DS) present unique challenges in control design due to their inherent algebraic and differential components.
• Actuator faults and saturation significantly degrade system performance and stability, necessitating robust fault-tolerant control (FTC) strategies.
• Existing control allocation (CA) techniques often struggle with systems having full rank input matrices or actuator saturation.

Purpose of the Study:

• To design an active fault-tolerant control (FTC) system for uncertain descriptor systems (DS) subject to actuator saturation.
• To develop a novel control allocation (CA) technique that effectively redistributes control efforts to healthy actuators.
• To ensure system robustness against actuator faults, estimation errors, and external uncertainties.

Main Methods:

• A variable gain super twisting sliding mode algorithm (VGSTSMA) was employed to design a virtual control law meeting admissibility criteria.
• The control strategy was based on the generalized regular form (GRF) of the DS, ensuring robustness.
• A static control redistribution mechanism was introduced to manage actuator saturation by re-allocating excess control efforts.

Main Results:

• The proposed CA-based FTC scheme demonstrated superior performance in a simulated dual-pipe heat exchanger system under actuator faults and saturation.
• The VGSTSMA-based strategy ensured robustness against faults, estimation errors, and uncertainties.
• The developed CA technique is applicable to DS with full rank input matrices, overcoming limitations of traditional methods.

Conclusions:

• The proposed CA-based FTC system, utilizing VGSTSMA and a static redistribution mechanism, effectively handles actuator faults and saturation in uncertain descriptor systems.
• The method offers enhanced robustness and applicability compared to traditional pseudo-inverse CA-based FTC and STA-based FTC.
• The simulation results validate the superiority and practical viability of the developed fault-tolerant control strategy.