The sigma-function for problem of states and disturbances observers synthesis

Based on the principle of motions separation, methods for the synthesis of states observer with nonlinear corrective actions in the form of sigma functions are developed for nonlinear systems, operating under uncertainties. It is shown that for the systems, that can be represented in the regular form relatively to external disturbances, this approach allows to obtain current estimates of unmeasured state variables and external disturbances without expanding of dynamic order of the observer. It is possible because of the model that simulates the effect of external disturbances. Algorithms developed are used in a control system for induction motor with incomplete set of measuring units.