Browsing by Author "Sonnenberg, Manuel"

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    Development of a rating system by means of extended economic appraisal using the digital twin for the design of cyber-physical production systems
    (Stellenbosch : Stellenbosch University, 2022-11) Sonnenberg, Manuel; Hummel, Vera; Von Leipzig, Konrad; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering.
    ENGLISH ABSTRACT: This study seeks to develop a rating system for the comparison of alternative production configurations, which incorporates criteria that are difficult to quantify. The increasing demand for individualization down to batch size 1, coupled with rising price pressure, ambitions to ensure good working conditions, and desire to meet sustainability goals, is forcing manufacturers to optimize their production systems comprehensively. Decisions on production order planning are currently based predominantly on quantifiable aspects, such as available resources and the corresponding financial means, while criteria that are difficult to quantify, such as the adaptability of the production system and the well-being of the employees, are regularly disregarded. This research thesis presents a comprehensive approach of a holistic rating system for the design of cyber-physical production systems (CPPS). The rating system combines a production scenario configurator with a simulation of occupation planning and an economic appraisal extended by the work system value. The aim of the research is to provide a procedure for the short-cycle determination of the most suitable smart production system for small batches, considering assessment dimensions that are expected to have long-term economic, ecological, and social value, and relevance. To achieve this, the simulation is expanded and rating formulas are applied that concentrate the information content while facilitating decision-making. Following the design science research methodology, this study covers both a quantitative and qualitative literature analysis of selected publications to derive a set of work system value criteria relevant to CPPS, and identifies indicators to operationalise them. This is followed by the abductive design of a digital twin-based configuration and rating tool, which is deductively validated with collected data from Werk150, the learning factory of the ESB Business School on the campus of Reutlingen University. The configuration element of the system suggests different possible production scenarios. These result from a variation in the form of production organisation, which entails a change in the division of labour and activity sequencing, as well as the allocation of available devices and agents. In order to make a comparison between the configured scenarios, an extended economic appraisal (EEA) is applied to each; it fuses a partial cost calculation to a work system value. The partial cost calculation is tailored to the aspects that differ between the production variants, material costs, and employee costs. The work system value, which extends the economic appraisal consists of weighted criteria: physical and mental stress; ecology; competence fit; delivery reliability; capacity utilisation; error potential; various flexibility corridors; all of which enable the utility comparison of alternative production scenarios. Information needed to anticipate the partial costs of production scenarios is provided by a time discrete simulation, which considers the properties of the different scenarios. The work system value also takes information from the simulation, but adds to it data collected from experiments.