On the observability codistributions of a nonlinear system

C.De Persis, A. Isidori
2000 Systems & control letters (Print)  
The purpose of this is to introduce the notion of observability codistribution for a nonlinear system, which extends the (dual of the) notion of "unobservability subspace". Then, we study its properties, which bear important similarities with a number of properties which render the notion of unobservability subspace powerful in the solution of certain design problems.
doi:10.1016/s0167-6911(00)00014-1 fatcat:vm4kdtrjgbbh3jauumt53alcmm