State Estimation and Fault Diagnosis for Nonlinear Analog Circuits

This paper demonstrates a new approach of fault diagnosis for the nonlinear analog circuits, which is based on the computation of maximum Lyapunov exponent of chaotic time series. We use this method to estimate the operating states of strong nonlinear analog circuits, and make a discussion on selecting a proper pair of embedding dimension and time delay for phase space reconstruction. This new fault diagnosis method is validated by an instance: the output signal of a harmonic oscillator with variable periods in radar is taken as the testing object, the surrogate method is used to generate the fault data, and the maximum Lyapunov exponent is calculated by means of the small data-set approach. The simulation testing results indicate that this method can efficiently find out the abnormal changes in nonlinear analog circuits