In this paper we propose a new state observer design technique for nonlinear
systems. It consists of an extension of the recently introduced parameter
estimation-based observer, which is applicable for systems verifying a
particular algebraic constraint. In contrast to the previous observer, the new
one avoids the need of implementing an open loop integration that may stymie
its practical application. We give two versions of this observer, one that
ensures asymptotic convergence and the second one that achieves convergence in
finite time. In both cases, the required excitation conditions are strictly
weaker than the classical persistent of excitation assumption. It is shown that
the proposed technique is applicable to the practically important examples of
multimachine power systems and chemical-biological reactors.Comment: 13 pages, 8 figure
