Section: New Results

Observability And Observer Design For Nonlinear Systems

Observability analysis and observer design are important issues in the field of control theory. Some recent results are listed below:

• The paper [12] deals with the observability analysis of linear time systems whose outputs are affected by unknown inputs. Three different definitions of observability are proposed. Sufficient conditions are deduced for each proposed definition.

• In [11] a method of the state estimation is proposed for a class of nonlinear systems with unknown inputs whose dynamics is governed by differential-algebraic equations (DAE). The estimation is done using a sliding mode high order differentiator.

• The recent algebraic parametric method proposed by Fliess and Sira-Ramirez has been extended to numerical differentiation problem in noisy environment [66] . The obtained algebraic differentiators are non-asymptotic and robust against corrupting noises.

• The paper [41] investigates the observer design problem of nonlinear impulsive systems with impact perturbation. By using the concept of normal form, it proposes a full order finite time observer, which guarantees the finite time convergence independent of the impact perturbation.

• The development of adaptive observer techniques for nonlinear systems in the output canonical form is proposed in [22] applying additional impulsive feedback in the observer equations. The stability is investigated.

• In [55] the problem of adaptive observer design in the presence of disturbances is studied, and an augmented adaptive observer is proposed using sliding mode methodology.