control//fault diagnosis

Fault diagnosis uses observations to distinguish a malfunction from expected system behaviour and, when the evidence permits it, identify its source. In a model-based approach, the difference between predicted and measured behaviour is a residual. A residual can reveal inconsistency without uniquely identifying the failed component.

Fault diagnosis uses observations to distinguish a malfunction from expected system behaviour and, when the evidence permits it, identify its source. In a model-based approach, the difference between predicted and measured behaviour is a residual. A residual can reveal inconsistency without uniquely identifying the failed component.

The two-tank example develops that distinction: several faults can produce overlapping signatures, and the model needs enough independent measurements to separate them. See controllability and observability for the limits of reconstructing internal state.