Improving the control performance of networked control systems using a new fuzzy PID

Abstract

This paper demonstrates the practical design and implementation of two common network-based control approaches using Foundation Fieldbus and Industrial Ethernet. The presented approaches utilize a Smar Foundation Fieldbus controller (DFI-302) for function block implementation and a remote Siemens programmable logic controller (S7-315-2DP) for networked control system implementation. A proper network platform has been designed to link these two controllers to a real pilot plant via Industrial Ethernet and Foundation Fieldbus. This paper investigates the effect of network data transmission delay on the resulting control performances. Then, a new fuzzy PID control strategy is proposed to improve the control performance due to transmission delay degradation effect. The supporting philosophy behind these three functional zones is to decompose the desired control objectives in terms of rising time, settling time and steady-state error measures maintained by an appropriate PID-type controller in each zone.