Table 2.

Advantages and disadvantages of the active supervision methodologies.

	Advantages	Disadvantages
Signal-based	Simple Fast	Expert knowledge required Symptoms similar in different faults Limited to detection/diagnosis tasks in ISO No attention to the dynamic behaviour of the system Expert knowledge required Many uncertainties difficult to be defined analytically Limited to diagnosis tasks in ISO High amount of data required Need for data storage platform High computational capacity
Model-based	Accurate in simple systems Easy to reach analytical redundancy
Data-driven	Accurate if data available Extend ISO to Prognostics Assessment