PRODUCTION ERGONOMICS EVALUATION - NEEDS, PROCEDURES AND DIGITAL HUMAN MODELING TOOLS

Licentiate thesis, 2009

In production systems, human operators may be at risk for developing work-related musculoskeletal disorders (MSDs), resulting in pain, inability to work and high costs. An increasingly capable tool for identifying MSD risks early in the production design process are Digital Human Models (DHMs), although their built-in analysis tools are in great need of development regarding how they address time-related aspects of load exposure. Time-related exposure phenomena provoking MSDs are e.g. repetitive work patterns, lack of variation, fatigue effects, work enlargement effects, and distributions of activity/rest. The aim of this thesis is therefore two-fold; to explore pragmatic industrial needs regarding ergonomics evaluation and compare this to the State-of-the-art of scientific evaluation methods that address time-related aspects. The first approach, a case study in an automotive setting, revealed that switching from one evaluation method to another in a factory may be for pragmatic contextual reasons rather than based on educated selection. It was also shown that companies who do this may unintentionally risk producing evaluation results that are not equal regarding criteria levels or degree of analysis detail, rendering results difficult to use for some actors in the process. The second approach, a literature review, categorizes several time-related ergonomics terms and has proposed a ‘process-flow’ framework for the terms, based on an input-throughput-output concept. This framework can give DHM tool developers an overview of which time-related aspects interact and which combinations are suited to different analysis goals. Lastly, the thesis reflects on actor roles and time perspectives.