Advanced PID Control Algorithms Built into the REX Control System

REX is an industrial control system which has been developed by the authors of this paper and by several their colleagues during the last decade. Control algorithms of REX are contained in a large function block library (block set). Controller blocks, including various PID controllers, cover a significant part of the library. This paper briefly explains main ideas of REX and it focuses on description of two advanced PID controller function blocks with built-in auto-tuning facilities. Both of these controllers use active identification experiment for the process identification, first of them uses a pulse experiment, second of them uses a relay experiment. After finishing of the identification experiment, the designed controller parameters are immediately computed in both cases. These controllers and some additional function blocks are presented in several examples demonstrating various control structures.