Development And Validation Of A New Methodology For Human-Centered Workstation Design

Nowadays, modern factories are paying a growing attention to human-centered workplaces, tailored to the needs of workers, as a recurring theme of Industry 4.0 [1]. This approach, which makes the worker at the center of the factory system according to a Human-Centered view [2], is based on a careful ergonomic analysis of the workstations, taking into account the cycle time required for the tasks completion and related recovery times. From the combination of factory ergonomics and time-method analysis, a new methodology has been defined to support the design of human-centered workplaces, called “ERGO-MTM-UAS”. This new methodology therefore aims to reduce the risks to the health of the worker’s musculoskeletal system (usually linked to repetitive tasks) associating a specific methodology of work time measurement (MTM-UAS) with an ergonomics assessment and risk factors evaluation checklist (EAWS). The analysis consists of three main steps: • • Assignment of a basic work time through the MTM-UAS methodology; • • Calculation of the recovery time considering the risk factor through the EAWS checklist; • • Definition of the total work time summing the basic time and recovery time. The industrial case study has been developed in collaboration with CNH Industrial, focusing on the assembly of ATS (After Treatment System) on the hood support of a large size tractor. The final aim was to validate the new methodology by applying to a real case study, comparing to the ideal case study without recovery time. To achieve this goal, a calculation sheet has been developed in Visual Basic code. In the first part, it allows to calculate the estimated time to complete a specific task, subdividing it in sub-tasks. In the second part, it allows to evaluate risks factors with the EAWS score and calculate the recovery time needed at the end of the entire task. In addition, the user could choice to insert postures data by the direct observation of workers but also from JACK Siemens postures data files. Fig.1 shows the results of the analysis on the case study: the estimated time to complete the selected task is about 12 minutes and 46,7 seconds by applying the MTM-UAS method, while the EAWS method suggests a recovery time of 2 min and 16 sec. The total time to achieve the task has been found to be 14 min and 34 sec, very close to the estimated time by recovery time. The results of this analysis confirmed the applicability of the new methodology, underlining the vital importance of adopting a careful ergonomic feasibility study to properly design complex and long-term assembly processes. The main advantage of the proposed method is the possibility to introduce an ergonomic assessment before the process creation, to be applied at the early stage of the design process, to assure reducing the workers’ musculoskeletal disorders and costs for workstation redesign. REFERENCES [1] Gregori, F., Papetti, A., Pandolfi, M., Peruzzini, M. and Germani, M., 2017. “Digital manufacturing system: a framework to improve social sustainability of a production site”. The 50th CIRP Conference on Manufacturing System, 2017 on Sustinable Manufacturing, Vol. 63 of Procedia CIRP, pp. 436 – 442. [2] May, G., Taish, M., Bettoni, A., Maghazei, O., Matarrazzo, A., Stahl, B., 2015. “A new Human-centric Factory Model”. 12th Global Conference on Sustinable Manufacturing, Vol. 26 of Procedia CIRP, pp. 103-108.