Information process flow analysis (IPFA) for reengineering manufacturing systems

Abstract

Automated manufacturing lines, aircraft, unclear power plants, and similar real-time intelligent or embedded systems contain three control elements: (1) embedded computers, (2) humans-in-the-loop, and (3) certain machines, i.e., mechanically, electrically, or electronically operated devices. Embedded system control elements are interconnected through accurate, precisely-timed, closed-loop information systems to provide high quality products and/or services from their parent systems, and in some cases to ensure human safety. Highly-reliable controlling computers and associated software embedded in time- and safety-critical systems that compensate for possible human and/or machine error are especially difficult to design and develop, or “forward engineer”. Reengineering embedded control elements in old systems is even more troublesome, especially when they require re-manufacturing, e.g., nuclear power plant refueling, aircraft avionics system upgrading, or manufacturing plant retooling. This paper describes how industrial engineers can assist in reengineering worn out, error prone, or obsolescent real-time manufacturing systems (embedded systems) by helping computer systems and communication engineers ensure that critical information control loops, both feed forward and feed back, are complete and efficient. Two conceptual models, the Embedded Computer System (ECS) physical model and the Object Transformation Process Model (OTPM) are used to guide a modified process flow analysis (PFA) of existing large-scale, complex embedded systems that takes into account process-supporting information. This modified PFA is called an Information Process Flow Analysis (IPFA).