Multiharmonic perturbations for nonparametric autotuning

The improvement of a recently developed method for closed loop nonparametri c system identification using multiharmonic perturbation signals is describ ed. Intended primarily as a method for the periodic online retuning of thre e-term controllers, the original method is shown to benefit from an improve d selection of its design parameters. A brief review of the original algori thm is first given, followed by discussion of the improved parameter select ion and an illustration of its benefits, with the aid of a typical numerica l example. The result is a computationally efficient algorithm enabling non parametric estimation of the process around the critical design frequency o f interest, while also maintaining minimal disruption to the process output during the identification phase. Periodic online retuning of the controlle r is then possible without the need for any further relay tests beyond its initial commissioning.