A Plc Based Mimo Pid Controller for Multivariable Industrial Processes

Abstract. Industrial processes are in general multi-input multi-output (MIMO) systems. Despite of that and because of the lack of good fine-tuning algorithms for MIMO controllers, they are usually treated as single-input single-output (SISO) ones for the purposes of control design and implementation. In that cases, the tuning procedure is frequently carried out taken one loop at a time and the results are usually not as good as would be expected. This work presents a MIMO PID structure that leads to a fine-tuning technique that can be carried out in real time. The MIMO PID new structure has been implemented in a low cost PLC. The controller was tested in a 2x2 MIMO benchmark plant with outstanding results. This paper presents details of the controller structure, the fine-tuning procedure and finally experimental results of the controller performance.