An observer theory is presented for nonlinear dynamic systems in this paper. Exponential observers are defined (asymptotic state estimators with exponentially decaying error). A Lyapunov-like method is introduced for the design of exponential observers. Two theorems are presented to give conditions on the system structure such that there exists an exponential observer for the given system. © 1975 Academic Press, Inc.
Kou, S. R., Elliott, D. L., & Tarn, T. J. (1975). Exponential observers for nonlinear dynamic systems. Information and Control, 29(3), 204–216. https://doi.org/10.1016/S0019-9958(75)90382-4