A controller management scheme for active fault-tolerant tracking: Linear discrete-time systems

Area of Science:

• Control Systems Engineering
• Robotics
• Aerospace Engineering

Background:

• Linear discrete-time systems are susceptible to unknown disturbances, input constraints, and actuator faults.
• Existing fault-tolerant control (FTC) methods may not adequately address these combined challenges.

Purpose of the Study:

• To develop an active fault-tolerant control (FTC) approach for linear discrete-time systems.
• To effectively manage controller actions and utilize a virtual actuator to mitigate faults and disturbances.

Main Methods:

• The proposed FTC approach integrates controller management and a virtual actuator concept.
• An online optimization method, formulated as a quadratic programming problem, is used for controller management.
• Input-to-state stability (ISS) criterion is proven for the closed-loop faulty system.

Main Results:

• The closed-loop system effectively suppresses disturbances and faults while satisfying input constraints.
• Linear matrix inequality (LMI) conditions are derived to minimize the ISS ultimate bound.
• Fault and state estimation errors are shown to converge to a small neighborhood of the origin.

Conclusions:

• The proposed active FTC strategy demonstrates robustness against disturbances and actuator faults.
• The method ensures system stability and constraint satisfaction in complex dynamic systems.
• Simulations on robotic systems, DC motors, and VTOL aircraft validate the control strategy's effectiveness.