ROBUST-CONTROL SYSTEMS WITH 2ND-ORDER OBSERVERS

For a nonlinear system with inexact measurements, which experiences ex ternal action and is described by a second-order matrix differential e quation with indeterminate parameters, an augmented observer is constr ucted as a second-order matrix, differential equation. Contrary to the prevalent opinion [8], such an observer does not require additional m easurement gages or preliminary filtering, unlike an observer in the f orm of a first-order matrix differential equation. If the observer spe ed is greater than the speed of the entire system by a specific amount , the observer evaluates the slate vector and the error in She model o f the object and measurement gages. This is helpful in constructing a combined linear control robust to the imperfections of the model of ob ject and measurement gages, as well as to high-frequency noises. The r obustness of a system to high-frequency parasitic dynamics is also stu died.