Reconfiguration schemes to mitigate faults in automated irrigation channels

In this paper we develop reconfiguration schemes to mitigate water level sensor and gate (actuator) failures in automated irrigation channels. Analytical redundancy inherent in the system is used for control and signal reconfiguration. Sensor faults are dealt with by estimating the correct value of the signal measured by the faulty sensor and using the estimated signal as input to the controller. A generic rule for the design of estimators is given which facilitates rapid design of a large number of estimators as required in a large scale irrigation network. An actuator fault necessitates relaxation of the control objective, and it requires both signal and controller reconfiguration. It is shown in simulations that the reconfiguration schemes work satisfactorily throughout the entire operating regime of the irrigation channel.