Implementation of Model Predictive Controllers in Programmable Logic Controllers using IEC 61131-3 standard

Abstract

This work presents a tool for implementing Model Predictive Controllers (MPC) in Programmable Logic Controllers (PLC). This tool is a Matlab library that automatically generates the controller’s code using IEC 61131-3 standards so that it can be directly imported into the PLC’s programming platform as an FBD block, which is designed to work using the cyclic mode of the PLC and has a limited maximum execution time. A hand-tailored optimization algorithm based on a fast gradient method named FISTA has been developed in order to reduce the necessary memory and computational resources. A complete architecture has been designed surrounding the MPC which provides the overall controller with a series of additional capabilities. The properties of the controller have been validated via a test-bed using a Modicom M340 PLC to control a quadruple-tank system. In addition, tests have been conducted in order to study the memory requirements.