Suboptimal state estimation for continuous-time nonlinear systems from discrete noisy measurements
Michael Athans, R. P. Wishner, Alessandro Bertolini · IEEE Transactions on Automatic Control · 1968
This paper presents the derivation of the dynamical equations of a second-order filter which estimates the states of a non-linear plant on the basis of discrete noisy measurements. The filter equations contain terms involving the second-order partial derivatives of the plant and output equations. Simulation results are presented which yield a comparison of the performance of the first-versus the second-order filter when applied to a nonlinear third-order system. The results indicate that the inclusion of second-order terms can markedly improve the filter performance.