Observer design applied to prognosis of system

This paper is dedicated to model-based prognosis to predict remaining useful life of a system. This methodology is applied on multiple time scale systems made up of a slow and a fast dynamic behaviors subsystems, defining damage state and state of system behaviors respectively. Prediction of remaining useful life implies to have a slow dynamic behavior subsystem model. Slow dynamic subsystem behavior is supposed to be unknown, only the structure is assumed to be known a priori. For that, in the fast dynamic behavior subsystem, unmeasured state are estimated based on the design of unknown input observers. Slow dynamic behavior state in the fast dynamic behavior subsystem is led back to an unknown input. High gain observer is used to obtain accurate state and unknown input estimates. Slow dynamic behavior model parameters are then identified with the previous estimates. Prediction of remaining useful life is finally achieved based on relative accuracy of the observer estimates. Pertinence of the proposed methodology is illustrated based on simulation results to an electromechanical oscillator.