Geometric and hierarchical FDI for the IFATIS two-tank pilot plant

In the control of complex dynamic plants, fault detection and isolation (FDI) is a prerequisite for a fault tolerant control architecture. In order to increase the reliability and robustness of the fault diagnosis, it is fundamental that the FDI system is given a hierarchical structure, reflecting, as far as possible, the natural decomposition of the plant into physical and/or logical subsystems. Through the use of the IFATIS two-tank benchmark, we illustrate the design and implementation of a hierarchical system for the detection and isolation of non-concurrent faults of sensors and actuators, based on the processing of suitably selected residuals, designed with geometric techniques. The FDI performance is demonstrated by realistic simulations performed on the identified model of the real system, including actual levels of input and measurement noise.