Autotuning in Cascaded Systems Based on a Single Relay Experiment

This manuscript deals with the automatic tuning of cascade control systems, that are frequently encountered in process control. A tuning method is presented, the main goal of which is to be simple to operate, and introduce a moderate process upset. The method combines an ad hoc relay-based identification procedure based on a single test, a specific choice of the controller blocks’ structure, and a set of tuning rules based on a particular use of the well known IMC principle. Simulations are reported to illustrate the effectiveness of the proposal within its applicability limits, that are characterised as rigorously as possible, and may be widened by some of the envisaged extensions.