On-line parameter identification of non-stationary continuous system with time-variant delay

A method of online parameter estimation of nonstationary continuous systems having unknown time-variant input delay is proposed and demonstrated by some computer simulations. The recursive running DFT (discrete Fourier transform) is employed to calculate a number of transfer gains at arbitrary specified frequencies. Input delay, as one of the unknown parameters to be estimated, is uncoupled with other parameters by combining the absolute values of system gains and their real/imaginary parts. A simple way for directly estimating system parameters including input delay is demonstrated by some examples of simple systems. A method of solution for a general system is then proposed and verified by an example