Integrated Adaptive Fault-Tolerant H∞ Output Feedback Control with Adaptive Fault Identification

An adaptive fault-tolerant H-infinity output feedback controller is designed for a linear system with actuator faults by incorporating an observer for actuator faults. This observer is improved from an unknown input observer to make it more appropriate for tracking all fault parameters. The sufficient condition of the existence for this observer is provided. Then, the adaptive fault-tolerant H-infinity feedback controller is proposed by using the estimated fault parameters. This controller can ensure the H-infinity performance of system and accommodate actuator faults simultaneously, but it requires solving nonlinear matrix inequalities. An implementation scheme is designed by translating the nonlinear inequalities to solvable linear matrix inequalities. Finally, the effectiveness of the adaptive H-infinity output feedback controller is validated by stabilizing a vertical takeoff and landing helicopter when its actuators suffer from faults.