Synthesis and implementation of procedural controllers for event-driven operations

Hybrid modeling and dynamic simulation of automated batch plants

A proposal is presented for the hybrid modeling and dynamic simulation of automated batch processing plants with dominant discrete-event behavior. The proposal encompasses current techniques for modeling continuous-time/discrete-event processes, synthesizing discrete-event controllers as well as the use of industrial standards for batch control. The result is a hierarchical-modular model of a plant in which process and control tasks are clearly differentiated. Implementation rules are established for a specific dynamic simulator capable of handling hybrid systems. The approach is demonstrated by building and verifying a complete model for an automated milk pasteurization plant. Results show that handling problems of realistic complexity is feasible using state-of-the-art technology.

Improving the development of event-driven control systems in the batch processing industry. A case study

This paper presents the results of an academia-industry collaborative project whose main objective was to test novel techniques for the development of event-driven control systems in the batch processing (e.g., pharmaceutical, fine chemicals, food) industries. Proposed techniques build upon industrial standards and focus on (i) formal synthesis of phase control logic and its automatic translation into procedural code, and (ii) verification of the complete discrete-event control system via dynamic simulation. In order to test the techniques in an engineering environment, a complete discrete-event control system was produced for a benchmark batch process plant based on a standard development method employed by one of the industrial partners. The control system includes functional process specification, control architecture, distributed control system (DCS) proprietary programming code for procedural control at equipment, unit, and process cell levels, and human-machine interfaces: A technical assessment of the development method and the obtained control system was then carried out. Improvements were suggested using the proposed techniques in the specification, code generation and, verification steps. The project assessed the impact of these techniques from both an engineering and economic point of view. Results suggest that the introduction of computer aided engineering (CAE) practices based on the benchmarked techniques and a structured approach could effect a 75% reduction of errors produced in the development process. This translates into estimated overall savings of 7% for green-field projects. Figures were compared with other partners' experience. It is expected that the work load on a given project will shift, increasing the load on process engineers during the specification stage and decreasing the load on the software engineers during the code writing.