T ighter performance specifi cations from worldwide competition and ever increasing constraints from environmental and safety considerations give the practical driving force for the development of advanced control technology (Findeisen and Allgöwer, 2001). Large amounts of industrial practice and academic research have made model predictive control (MPC) the de facto standard algorithm for advanced control in the process industry (Nikolaou, 2001). MPC is a general and mathematically feasible scheme to integrate our knowledge about a target, process into controller design and operation, which allows fl exible and effi cient exploitation of our understanding of a target, and thus optimal performance of a system under various constraints. Three key factors responsible for the great success of MPC are the incorporation of a process model, an algorithm considering plant behaviour over a future horizon in time, and explicit treatment of constraints (Qin and Badgwell, 1999), with the model being foremost and fundamental.For an accurate and reliable prediction of a model, suffi cient information input is the most important factor, though algorithms in the model are equally important regarding the use of the input information. It is well known that combined feedforward plus feedback control can signifi cantly improve performance over simple feedback control whenever a major disturbance exists. It can be measured before it affects the process output, and methods for designing linear feedforward/feedback control systems are well documented in standard textbooks such as that of Stephanopoulos (1984). Such methods are also suitable for nonlinear systems where the effect of measured disturbances (DVs) can be separated from that of manipulated variables (MVs). However, for systems where DVs and MVs are closely coupled together, a unifi ed model correlating both kinds of variables is necessary and should be inverted online. At this time, MPC is a ready solution. Just as pointed out by Economou et al. (1986), MPC has the capability to combine the advantages of open-loop (feedforward) and feedback control. A future horizon in time considered in the MPC algorithm means that the effects of measured and unmeasured disturbances can be predicted and eliminated (Qin and Badgwell, 1999). Developing a valid model for process dynamics is often the major work in the implementation of an advanced control. More than 75% of the expenditure in an advanced control project normally goes to modelling. Artifi cial neural networks (ANNs) as a process model for control purpose are superior to other conventional modelling methods for reasons of complexity, accuracy, fl exibility, generality, execution speed and cost (Bhat and McAvoy, 1990;MacMurray and Himmelblau, 1995; Hussain, 1995). They have been widely studied in various modelbased control strategies. Various types of neural networks have been studied in the literature of process control, and the multilayered feedfor-
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