On-line monitoring and accommodation of nonlinear actuator faults in positive real infinite dimensional systems

We consider a class of positive real infinite dimensional systems which are subjected to incipient actuator faults. The actuator fault is modelled as a time varying transition from an initial (linear or even hysteretic) map into a(another) hysteretic map at the onset of the fault occurrence. An infinite dimensional adaptive detection observer is utilized to generate a residual signal in order to detect the fault occurrence and to assist in the fault accommodation. This is done via an automated control reconfiguration which utilizes information on the new hysteretic map and adjusts the controller via a static right inverse of the new actuator map. A robust modification is utilized in order to avoid false alarms caused by unmodelled dynamics. An example is included to illustrate the applicability of the proposed detection scheme.