Cascade Design of State Observers

A block approach to designing state observers for nonlinear multivariate systems is developed. A block-observable form of nonlinear systems is elaborated, in which the design of dynamic observation devices is subdivided into sequentially and independently solved elementary subproblems of reduced dimension. Stepwise procedures for choosing state observer controls from high-gain feedback systems are developed. Lower estimates for the finite coefficients of state observers are used in estimating the state vector components with given accuracy via synthesis decomposition. The designed algorithms ensure the invariance of the control operator to parametric uncertainties. By way of application, the state variables of an asynchronous sensorless drive motor are estimated from stator current measurements.