Assessment and Future Directions of Nonlinear Model Predictive ...

Experiences with Nonlinear MPC in Polymer Manufacturing 397The engineering interface is much richer, allowing all the operator interactions,as well as allowing changes to controller tuning. Both operator and engineeringinterfaces are required to have role-based security to avoid unauthorized personnelmaking changes that affect the plant.9 BenefitsDemonstrated project results show:1. Capacity Increase: 2 − 10%2. Off-spec reduction during transition: 25 − 50%3. Off-spec reduction during steady state operation: 50 − 100%The direct quantitative benefits are significant and are typically in the region of$400, 000 to $1, 000, 000 per line per year. Qualitative benefits include:1. Minimizing product transition times2. Minimizing variability in quality3. Maximizing production capacity4. Reducing raw material consumptions5. Reducing downtime and maintenance cost6. Reducing safety stocks and slow-moving inventory10 ConclusionsThis paper has examined some of the technological and practical issues faced inimplementing nonlinear control on industrial continuous polymer manufacturingprocesses. Descriptions of modelling technology and controller technology havebeen given with emphasis on practical solutions. The importance of suitablemodels has been emphasized, and it is surely a fruitful area of research for theacademic community to find more and better ways to impose process and fundamentalknowledge onto simple control-suitable models structures – to bridgethe gap between complex continuous-time rigorous models and simple discretetimemodels with well-understood gain characteristics. In addition, it would bevery useful to develop control theoretic results on stability, observability, controllability,problem convexity, etc. within the context of these reduced scopemodels.References[1] Eric C. Kerrigan and Jon M. Maciejowski, “Designing model predictive controllerswith prioritised constraints and objectives.”, Proceeding of the IEEE Conferenceon CACSD, Glasgow, pages 309-315, (2002).[2] W.C. Li and L.T. Biegler, “Multistep, Newton-type control strategies for constrainednonlinear processes.”, Chemical Engineering Research Design, pages 562-577, (1989).