Identification of time-varying thermocouple systems

The present study addresses the problem of estimating time-varying time constants associated with thermocouple systems by a set of basis functions. By expanding each time-varying time constant onto a finite set of basis sequences, the time-varying identification problem reduces to a parameter estimation problem of time-invariant (TIV) system. The proposed method combines the orthogonal least squares (OLS) algorithm with an error reduction ratio (ERR) test to include significant basis functions into the model, which results in a parsimonious model structure. The performance of the method was compared with a Kalman filter. Simulations on engine data have demonstrated that the proposed method performs satisfactorily and is better than the Kalman filter.