Optimal design of hybrid controllers for hybrid process systems

Abstract

The design of controllers for processing systems has mostly concentrated on the purely continuous and purely discrete cases. However, most chemical processes exhibit hybrid characteristics. This work presents a model-based approach to the controller synthesis problem for hybrid processing systems. A parameterised representation for hybrid controllers is presented that generalises the purely discrete and purely continuous cases. A discrete/continuous mathematical model of the process and the control system is constructed. Then, the mathematical formulations of the control system design and performance verification problems are introduced. The former can be used to design a controller that behaves optimally with respect to a given finite set of disturbance scenarios. The latter, given a controller, determines worst-case disturbance inputs that render the system infeasible or suboptimal. The two problems are finally combined into a two-stage, iterative design algorithm. A simple example is used to illustrate the potential of the proposed approach.