KANBrief 3/13
Modern computer-aided tools provide numerous ways of improving ergonomics and therefore workplace safety and health. An example are digital human models (DHMs), which are becoming increasingly important for the planning of good work equipment and work systems. The aim for the future will be to increase the usability of these tools and to extend the scope of their application.
Virtual planning enables the effects of decisions to be determined immediately during the process of work equipment design and the preparation of work processes. For this purpose, the work equipment and work systems are initially only modelled in the computer. The objective is to simulate interaction between human beings and technology with sufficient precision. A range of digital human models exist on the market that for example model processes of movement three-dimensionally and determine and evaluate physical stresses. The designer is able to set various parameters according to the user group, and thus to arrive at conclusions regarding reachability, fields of vision, etc. This in turn enables design faults to be avoided at an early stage, before the simple mentation phase.
At present, the primary area of application of these software systems is the automotive industry. In this area, DHMs are used both for product design (such as the passenger compartment of cars, simulation of entry and exit) and during process planning and the development of solutions for assembly of the vehicles (e.g. reach ability analyses).
From the standard to the human model
Anthropometric data serve as an important foundation for numerous aspects of design, for example for the specification of safety distances. Such data can be found for example in the DIN 33402, "Ergonomics – Human body dimensions" and EN ISO 7250, "Basic human body measurements for technological design" series of standards. Since these standards do not however contain all data required for the various areas of application of human models, they cannot always be directly applied in full. Major software manufacturers therefore frequently use commercial data, which are more comprehensive and up to date and which lend themselves more readily to integration into 3D software applications.
Principle specifications for human models have been developed in the EN ISO 15536 series of standards, "Ergonomics – Computer manikins and body templates". EN ISO 15537 "Principles for selecting and using test persons for testing anthropometric aspects of industrial products and designs" contains principles for selecting and using collectives for evaluating work equipment and work systems by means of anthropometric data.
Standardization of human models and data interchange
Further tasks lie ahead. A Delphi study (Systematic, multi stage consultation process with feedback that is conducive to optimum estimation of future events, trends, technical developments and the like) conducted by the Federal Institute for Occupational Safety and Health (BAuA) particularly identified the following needs directly related to standardization (cf. Wischniewski, S.: Digitale Ergonomie 2025 – Ergebnisse einer Delphi Studie der BAuA. See proceedings (in German), "Digitale Ergonomie", BAuA 2013, pp. 30-46):
• Development of a data interchange format for human models (anthropometric and bio mechanical parameters, movement data, etc.), in order to facilitate the transfer of research results into commercial software systems and the exchange of simulation results within the research community. EN ISO 15535, "General requirements for establishing anthropometric databases", which already defines a format for the handling of anthropometric data, may serve as a starting point for this purpose.
• Development of a standardized human model (for example by specification of the nomenclature and number of the minimum joints required, and of their degrees of freedom and orientation), for example by further development and substantiation of the EN ISO 15536 series of standards.
An important role in the ongoing development of DHM is played by the "Human Simulation and Virtual Environments" Technical Committee of the International Ergonomics Association (IEA). Since 2011, experts have used this committee to discuss new developments, and to analyse what results should be incorporated into standards.
Digital human models are already able to contribute to the design of safe and healthy work. Owing to their complexity, their use is currently restricted primarily to experts in computer-aided ergonomics. In future, it will be desirable for these systems to be made available to a wider user group (such as engineers), for example by improved usability of the software.
Dr. Sascha Wischniewski
wischniewski.sascha@baua.bund.de