Adaptive actuator failure compensation for nonminimum phase systems

An adaptive control scheme based on pole placement control is developed for linear time-invariant systems with unknown actuator failures to achieve output tracking using output feedback. The developed control scheme is applicable to both minimum and nonminimum phase plants. The actuator failures are characterized by the failure patterns that some control inputs are stuck at unknown fixed values at unknown time instants and cannot be influenced by the control signals. When both plant and actuator failure parameters are known, a detailed analysis shows the existence of a nominal controller that achieves the desired pole placement, output tracking and closed-loop signal boundedness. When both plant and failure parameters are unknown, an adaptive scheme is proposed and adaptive law for parameter estimation is developed, under reduced design conditions on the system, as compared with existing work. A simulation study with a linearized lateral dynamics model of the DC-8 aircraft is presented to verify the desired system performance in the presence of unknown actuator failure.