A component-based approach to design and construction of change capable manufacturing cell control systems
Business goals of manufacturing systems are typically in a state of constant change and greater rates of change are predicted in the future. Whereas contemporary approaches to the design and construction of these systems often results in inflexible enterprises that cannot readily be tuned to changing business goals. This study has specified and prototyped the use of a new model-driven approach to the design and (re)configuration of"change capable" manufacturing cells. Manufacturing cells represent a typical domain of manufacturing systems in which the existence of inflexible links between tasks and resources can result in sub-optimal performance and an inability to cope with change. The approach is based on a) the use of a semi-generic model of manufacturing cells, that structures and targets the use of CIMOSA modelling constructs (as implemented by the SEWOSA tool) towards producing a requirements specification and conceptual design in the form of a graphical and computer executable model of a particular manufacturing cell, and b) the complementary use of new computer executable modelling constructs and tools, that structure and support the detailed design and runtime operation of a particular cell in the form of an explicit, model-based configuration of cell resources and software components that realise the control processes required in a particular cell. Part of the semi-generic model comprises descriptions of common tasks found in a given domain of manufacturing cells. That part of the model has been captured and formalised by using CIMOSA modelling constructs. A new development of this modelling structure allows pre- modelled tasks to be selected, detailed and organised and suitable resources and reusable control system components (or building blocks) assigned to groups of tasks. Thereby this new approached to designing and building manufacturing cells can facilitate rapid and effective design and reconfiguration of manufacturing cell control systems. General information requirements found during the modelling and real world application of target cells, have also been formally defined and are met by using a suitable modelling structure and specially developed tools. Furthermore, the research has shown how modelled sets of software component building blocks can be specified and implemented as modular, reusable elements of manufacturing cell control systems. New modelling structures have been conceived and fonnalised and examples of their use evaluated under laboratory conditions. The research has also deployed and developed pre-existing enterprise modelling concepts and integration tools, including CIMOSA, STEP, EXPRESS, CIMBIOSYS infrastructure services and component-based software design concepts. This has enable the creation of a prototype tool-set that demonstrates how the concepts can be beneficially applied. The main contributions made by this research are that: a) It proposes and develops an approach to the design of manufacturing cell systems that successfully bridges a previous gap between top-down modelling concepts, methods and tools (that typically support formal modelling of system requirements, tasks and resources) and bottom-up detailed design and build techniques that lead to the operation, control and monitoring of real cells, b) It provides a modelling and implementation structure that 'integrates' the use of a classical enterprise modelling approach (namely CIMOSA), design primarily to support the designers of manufacturing systems, to the emerging component-based design and build concepts, that are becoming popular with software and system vendors.