Fault diagnosis and fault-tolerant control in aerospace systems

Modern technological and safety‐critical systems rely on sophisticated control solutions to meet increased performance demands in faulty conditions and in terms of reliability and safety requirements. A conventional feedback control design for a complex system may give 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 aircraft and spacecraft. 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 reliability, safety, and availability while providing desirable performances. These types of control systems are known as fault‐tolerant control systems. In more detail, they consist of control systems possessing the ability to accommodate component faults automatically. 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 that can tolerate component malfunctions, while maintaining desirable performance and stability properties is considered to be a fault‐tolerant control system.