Bank of virtual actuators for fault tolerant control

We propose an actuator fault tolerant control scheme based on a bank of virtual actuators (VA), with the novel feature that the virtual actuators implicitly integrate both fault detection and isolation (FDI) and controller reconfiguration (CR) tasks. The bank of VAs operates in closed-loop with an observer-based tracking controller designed for a nominal (fault free) model of the plant. We consider abrupt actuator faults ranging over a finite cover. Each VA is designed to operate appropriately in combination with the nominal controller to achieve correct CR for a particular fault situation in the considered range. A switching rule that engages the suitable VA from the bank is based on sets defined for measurable residual signals constructed directly from the virtual actuators signals. The overall scheme is shown to guarantee closed-loop boundedness and setpoint tracking under all considered fault situations. The method is applied to an example of lateral aircraft control.