[Preface] : Safety, Fault Diagnosis and Fault Tolerant Control in Aerospace Systems

Modern technological and safety-critical systems rely on sophisticated control solutions to meet increased performance in faulty conditions, reliability and safety requirements. A conventional feedback control design for a complex system may result in an unsatisfactory performance, or even instability, in the event of malfunctions in actuators, sensors or other system components. To overcome this limitation, new approaches to control system design have been developed in order to tolerate component malfunctions while maintaining desirable stability and performance properties. This feature is particularly important for safety-critical systems, such as aircrafts and spacecrafts. In such plants, the consequences of a minor (abrupt or incipient) fault in a system component can be catastrophic. Therefore, the demand on reliability, safety, availability and fault tolerance is generally high. It is necessary to design control strategies that are capable of tolerating potential faults in order to improve the reliability, safety and availability, while providing desirable performances. These types of control systems are known as fault tolerant control systems. Particularly, they consist of control systems possessing the ability to automatically accommodate component faults. They are also capable of maintaining overall system stability and acceptable performance in the event of such faults. In other words, a closed-loop control system which can tolerate component malfunctions while maintaining desirable performance and stability properties is considered to be a fault tolerant control system.