A PID autotuner based on the Astrom and Hagglund method using nonuniform sampling

A method is described for tuning a PID controller so that the controlled system gets the desired phase or amplitude margins. By introducing nonuniform sampling and applying the procedure proposed by K. J. Astrom and T. Hagglund (1984), it is possible to estimate the characteristics of the process needed for tuning of the PID controller. The estimation is based on the describing function technique. The design is verified by applying the autotuner to some simulated examples where the process model is well known.<<ETX>>