Robust control and its implementation in PLC for multi-hoist surface treatment lines

This paper presents a robust control approach for a class of production systems, the surface treatment lines. Our research is aimed at implementation techniques of robust control in PLC. A robust control is based on Petri Net modelling; scheduling sequence is described by PN model, equations for on-line control are derived by structural analysis. It helps us to explore the margins of capacity in order to cope with unpredictable perturbation of a sequence, whose interval of cyclic solution is calculated. The equations describing the PN model and the transport cycle of the PN are implemented in PLC by the technique proposed.