Model-based Proportional-Integral/Proportional-Integral-Derivative (PI/PID) autotuning with fast relay identification

Based on some relationships between model- and relay-based tuning, a novel tuning approach is proposed to couple the advantages of model-based methods and the simplicity and clarity of relay experiments. Based on that approach, some very simple synthesis procedures are derived for proportional-integral (PI), proportional-integral-derivative (PID), and more complex regulators. The procedures are fast, because they use a single relay test and do not introduce large process upsets. They are also very light, from the computational standpoint, and, thus, are well suited for low-end industrial regulators. Both simulation examples and laboratory tests are reported.