A Nonlinear Observer to Estimate the Effective Reproduction Number of Infectious Diseases

In this paper, we design a Nonlinear Observer (NLO) to estimate the effective reproduction number ( ℛ t ) of infectious diseases. The NLO is designed from a discrete-time augmented Susceptible-Infectious-Removed (SIR) model. The observer gain is obtained by solving a Linear Matrix Inequality (LMI). The method is used to estimate ℛ t in Jakarta using epidemiological data during COVID-19 pandemic. If the observer gain is tuned properly, this approach produces similar result compared to existing approach such as Extended Kalman filter (EKF).