Automated PI control tuning to meet classical performance specifications using a phase locked loop identifier

Non-parametric and model free approaches to classical controller design are enjoying interesting research attention at present. The non-parametric methods that originated from the seminal work of Ziegler and Nichols have lead to the relay method for obtaining the ultimate data of a system. This is followed by the application of a rule-based method to determine the coefficients of a PID controller. A different non-parametric method, developed by the authors, is the phase locked loop (PLL) approach. In this paper, it is shown how the PLL module can be used to drive an automated PI controller-tuning algorithm to achieve classical performance specifications. The new algorithm yields a PI controller achieving specified maximum sensitivity and phase margin values. The algorithm is one of a family of constructive routines able to automate PI design for a combination of classical performance specifications. The paper reports experience gained with a MATLAB/SIMULINK implementation