Nonlinear Reduced-Order Observers Based On Differential Riccati Equation

The paper deals with the design of reduced-order observers for Lipschitz nonlinear time-variant systems. Under the assumption that a differential Riccati equation has a positive definite solution, we put forward a design method of reduced-order observer whose output can approach to the true state with exponential convergence. The gain of the observer is computed based on the solution of the differential Riccati equation and it is non-constant. The simulations to an actual model show that the proposed observer has a good performance.