Interval observer composed of observers for nonlinear systems

For a family of continuous-time nonlinear systems with input, output and uncertain terms, a new interval observer design is proposed. The main feature of the constructed interval observer is that it is composed of two copies of a classical observer whose corresponding error equations are, in general, not cooperative. The interval observer is globally asymptotically stable under an appropriate choice of dynamic output feedback which uses the values of the output and the bounds provided by the interval observer itself.