Positive invariant sets for fault tolerant multisensor control schemes

Positive invariance is a common analysis and control design tool for systems affected by constraints and disturbances. The present paper revisits the construction of ǫ-approximations of minimal robust positive invariant sets proposing contractive procedures in the cases of switching between different sets of disturbances and the inclusion of a predefined region of the state space. The results are used in multisensor control schemes which have to deal with specific problems originated by the switching between different estimators and by the presence of faults. Within this framework, global stability of the switching strategies can be assured if the invariant sets topology allows the exclusive selection of estimates obtained from healthy sensors.