The main goal of the works developed by the research group dedicated to "Dependability and system diagnosis" (french acronym SURFDIAG), relates to the elaboration of a global approach for the design and the operation (supervision, maintenance, reconfiguration) of complex automated industrial systems. The dependability, also known as RAMS (for Reliability, Availability, Maintainability and Safety) in the concerned community, can be split into several subproblems.

Firstly, at the design stage, it is necessary to guarantee the system safety, i.e. to guarantee that the system will operate according to the given specifications (in normal operation mode) and forecast alternate modes allowing the system to continue to operate even if some part of it are out of order.

Secondly, at the operating stage, the supervision system must:
- detect any fault, i.e. decide that the system does not operate normally, using the overall available information on the actual behavior (obtained through the measurements) and on the expected behavior (often forecast by a system model or a model of the data);

- isolate the faults, i.e. decide which function (or, at least, which component) is faulty based on data redundancy;

- compensate for the faults, i.e. conceive and implement a fault tolerant control (that leads eventually to a degraded system performance) or reconfigure either the control architecture or, if it is possible, the process architecture itself.