  The design of an observer-based state feedback (OBSF) controller with
guaranteed passivity properties for port-Hamiltonian systems (PHS) is addressed
using linear matrix inequalities (LMIs). The observer gain is freely chosen and
the LMIs conditions such that the state feedback is equivalent to control by
interconnection with an input strictly passive (ISP) and/or an output strictly
passive (OSP) and zero state detectable (ZSD) port-Hamiltonian controller are
established. It is shown that the proposed controller exponentially stabilizes
a class of infinite-dimensional PHS and asymptotically stabilizes a class of
finite-dimensional non-linear PHS. A Timoshenko beam model and a
microelectromechanical system are used to illustrate the proposed approach.
