CANAL CONTROL ALGORITHM FORMULATIONS

Over the past two decades, numerous automatic control systems have bee n proposed for irrigation canal operation. Types of automatic control systems range from empirically based, for a one-canal pool, to multiva riable multipool procedures, based on the minimization of quadratic pe rformance criteria. Most control algorithms can be expressed in standa rd control theory terminology, from which properties and characteristi cs can be determined. The determination of the control action or contr ol variable required to obtain some desired canal operation as a funct ion of the design technique used is presented. The control laws associ ated with the different design techniques are shown in an RST polynomi al form, where R(q(-1)), S(q(-1)), and T(q(-1)) are polynomial matrice s in the backward shift operator, q(-1), associated with the control v ariables, controlled variables, and reference profiles, respectively. These expressions clarify the differences between the algorithms and t heir limitations when they are used in the operation of irrigation can als. A discussion is presented on the selection of these different alg orithms for situations of interest in canal automation.