  This paper utilizes the recently proposed cubic observer to estimate the
state of a class of nonlinear systems. The cubic observer is proposed as an
alternative to linear observers for improved convergence rate and robustness.
It is shown that the proposed cubic observer can enhance the estimation
compared to linear observers used for the same process. The proposed observer
can be viewed as a generalization to the linear observer. To further enhance
the cubic observer, a composite observer is proposed which combines the high
gain observer design principle with the cubic observer structure. An example is
included to show the efficacy of the proposed observer.
