Cost modelling for feedback control adjustment

摘要

Process control is a management problem in the performance analysis of a continuous production process. Statistical process monitoring and feedback control recently have been of interest to process control practitioners. It is imperative for the process control practitioner to know the costs of sampling and adjusting a process in order to minimize the manufacturing cost without compromising the objectives of process control. This view is kept as a basis when proposing a cost modelling methodology using some of the sampling and cost modelling principles available in literature. The sampling (adjustment) intervals are obtained by direct simulation of a feedback control algorithm in the proposed methodology. The algorithm is developed by the application of statistical and automatic process control techniques. The suggested method to develop the cost model and the associated cost functions uses adjustment intervals and is less complex. The cost function for feedback control adjustment is based on a second-order transfer function process model and a first-order noise model. The cost model and a corresponding control regulation scheme have applications in basis-weight control on a paper machine and in a batch-polymerization process that produces polymer resins in two groups of batch reactors that run in parallel and share common raw materials.