Actuator fault-tolerant control design: demonstration on a three-tank-system

Fault-tolerant control or reconfigurable control systems are generally base d on a nominal control law associated with a fault detection and isolation module. A general review of techniques dealing with this problem is given a nd a new fault-tolerant control approach is presented. This method is based on the on-line estimation of an eventual fault and the addition of a new c ontrol law to the nominal control law in order to reduce the fault effect o nce this fault is detected and isolated. The performances of this method de pend on the time delay between the occurrence of the fault and its detectio n and isolation. A modified approach is then proposed in order to avoid the problems generated by delays, false alarms or non-detection inherent to di agnosis techniques. These methods are applied to a pilot plant and their pe rformances are compared and discussed.