Unknown-input observation techniques in Open Channel Hydraulic Systems

This paper addresses a problem of state and disturbance estimation for an open channel hydraulic system. More precisely, a cascade of n canal reaches, joined by gates, is considered, and, by using measurements of the water level in three points per reach, we design an observer capable of estimating both the infiltration and discharge in the middle point of each reach. To facilitate the observer design, the system dynamics is modeled by considering a linearized approximation of the underlying nonlinear dynamics around the subcritical uniform flow condition. The proposed solution is based on the unknown-input and proportional-integral observers theory. Simulation results are discussed to verify the effectiveness of the proposed schemes