Robust eigenstructure assignment in the computation of friends of output-nulling subspaces

In this paper we develop a strategy for the computation of basis matrices of output-nulling subspaces, as well as of reachability and stabilisability output-nulling subspaces, with the simultaneous computation of the corresponding friend that also delivers a robust closed-loop eigenstructure. We show that the methods introduced in this paper offer considerably more robust eigenstructure assignment than the other commonly used methods employing subspace recursions.