Auto-tuning with multiharmonic perturbations. I. Nonparametric closed loop identification

This paper discusses identification schemes for the online auto-tuning of three-term controllers using multiharmonic perturbations. The emphasis in the schemes discussed lies in developing computationally economical algorithms suitable for implementation in controllers with modest processing power. In this paper an established method is used to develop new algorithms with reduced computational cost and gives an example of identifying the -180 degree point used in classical tuning rules such as Ziegler-Nichols. An example is demonstrated in the context of the -135 degree point used in the Kessler-Landau-Voda tuning method