Dan Högberg

Ergonomics analysis in a virtual environment

Simulation can support the design of an ergonomic workplace by enabling early assessment of ergonomic conditions in a virtual environment. An important feature is the possibility to study alternative solutions or the effect of improvements from an ergonomics perspective. To be able to conduct an efficient and reliable evaluation in a virtual environment, an objective analysis method is essential. Such an analysis method should be integrated in the simulation software, and support a companys everyday ergonomics work process. In order to gain from existing ergonomics knowledge within a company, the possibility to implement such wisdom in the current simulation software becomes important. This paper presents an implementation work done with the purpose of integrating an established ergonomics work process into a virtual environment. It describes the benefits of an ergonomics work process where simulation and evaluation at early stages of a design process are key factors. The paper will also describe the integration process, i.e., the technical issues as well as the change in work methods.

Industrial customisation of digital human modelling tools

Computer aided visualisation and simulation enables earlyevaluation of important design parameters of future products and productionsystems. Typically, humans affect the system performance, and in order toachieve the expected system efficiency ergonomics needs to be considered inthe design process in addition to the more technical or logistical matters.Hence, there is a call for ergonomics to be a natural part of the product andproduction development process, also at virtual stages. Three examples of thedevelopment of Digital Human Modelling-(DHM)-based company-specific

Description of boundary case methodology for anthropometric diversity consideration

This paper describes and evaluates the boundary case methodology for the simultaneous consideration of variance for a number of selected anthropometric variables. The methodology includes the calculation of key dimension values for extreme but likely anthropometric measurement combinations. This data can be applied when utilising digital human modelling (DHM) tools for proactive design work and entered as input data when representative manikins are defined. The mathematical procedure is clearly described and exemplified to demonstrate how to use the methodology in design work. The outcome of the method is illustrated and compared using several different cases where the number of measurements is varied and where principal component analysis (PCA) is used to reduce the number of dimensions in one case. The paper demonstrates that the proposed boundary case method is advantageous compared to approaches based on the use of univariate percentile data in design.

Creating and shaping the DHM tool IMMA for ergonomic product and production design

The history, status and outlook of the research and development actions associated with the creation of the digital human modelling tool intelligently moving manikins (IMMA) are described. The underlying fundamental concepts are described and research and development results so far are illustrated or referred to. Two case studies illustrating use of IMMA on industry-based problems are described. The paper also covers reflections on conceptions for prospective DHM tool developments from a general perspective, relating to areas of ergonomics and design methodology, as well as describing some of the plans for further developments and applications of the IMMA tool. These may be of assistance when identifying challenges for future research and development of DHM tools that are used in product and production design processes in industry.

Using a formal high-level language and an automated manikin to automatically generate assembly instructions

This paper presents an approach to automatically generate predetermined motion time system (PMTS) based assembly instruction lists from simulations within digital human modelling (DHM) software. A formal high-level instruction language is used to instruct an automated manikin to perform assembly operations. The manikin, the language and the assembled objects are composed into a discrete model. In a post-computational step, the model is used to construct PMTS instruction lists by mapping the manikin motions, assembled objects and the language instructions onto a set of PMTS keywords. The described approach is implemented in the DHM software IMMA and tested on industrial cases of manual assembly in the automotive industry.

IMMA – intelligently moving manikins in automotive applications

INTRODUCTION Digital human modelling (DHM) has been introduced in the product and production development process to provide the possibility of early analysis and verification of human-product and human-production system interaction. Digital human modelling is relatively widely used within automotive industry (Paul et al., 2012). Digital human modelling can be used to analyse both human postures and motions. Several techniques have been explored for the generation of manikin motions. Neural networks, a structure that should imitate the human brain, and fuzzy logics, a logic that should imitate human reasoning, have been tested in combination (Hanson et al., 1999). Currently no commercial digital human modelling tool on the market uses this combination to generate motions. In Siemens’ ergonomics simulation and visualisation tools two approaches are currently used: a task-based simulation approach with inverse kinematics (Raschke et al., 2005), and an approach that modifies root motions gathered from real humans using motion capture systems (Park et al., 2008). Motion captured recorded motions are also used in EMA where base motions from a reference database, similar to base tasks in predetermined motion time systems, is put together into new unique motion combinations (Fritzsche et al., 2011). Even though these approaches are available, most commonly the manikin is manually manipulated joint by joint, which gives drawbacks such as that manual adjustment is time consuming and posture and motion results may vary, both within and between tool users (Lämkull et al., 2008). From an industrial point of view such variation within the process is not a sustainable way of working. Frequently the validity of the manually generated manikin postures and motions is questioned. Therefore, researchers and industry use motion capture systems in combination with ergonomics simulation and visualisation tools. Motion capture systems require typically a laboratory like environment and physical prototypes. Hence, in using such a set-up, several of the advantages with virtual design and manufacturing disappear or are reduced. Therefore there is a call for valid motion generators in digital human modelling tools in order to support proactive ergonomics (Chaffin, 2005).

Simulation of Human-Vehicle Interaction in Vehicle Design at Saab Automobile: Present and Future

Developers, reviewers and users of human simulation tools claim that the use of these tools may reduce development time and development cost. However, before these benefits will be fully visible, there are some barriers to overcome. The aims of this case study are to identify which departments at Saab Automobile use some sort of human simulation tool today, and to identify the information flow and procedure when the tool is used. Four departments crash safety, packaging, production planning and vehicle ergonomics were identified as direct users of human simulation tools. The tools used were finite element with crash dummy representation, SAE human model, Safework and Ramsis. Communications between human simulation tool users are limited. Communications are done through the project management. The crash safety and packaging departments have formal descriptions of the human simulation process, whereas production planning and vehicle ergonomics have no formal process descriptions. To gain from the benefits of human simulation tools, Saab Automobile needs to adapt them to the organization and the organization to the tools. Integration of a working methodology is essential for effective and efficient use in the other human simulation departments where this is currently lacking. (Less)

The effect of information mobility on production quality

This article investigates the use of a hand-held unit as an information source in manual assembly. Having a mobile information system, such as a Personal Digital Assistant (PDA), that can be brought at all times, as opposed to a stationary one, such as a computer terminal, is hypothesised to increase the information range and thus improves assembly performance. The increased information range is argued to be due to assembly workers employing a cost–benefit strategy, where the cost of gathering information is compared with the assumed benefit of it. This article reports empirical data comparing the use of a mobile information carrier with a traditional stationary computer, and results show that the use of a PDA significantly improves quality, whereas productivity does not significantly improve quality.

Using experimental design to define boundary manikins

When evaluating human-machine interaction it is central to consider anthropometric diversity to ensure intended accommodation levels. A well-known method is the use of boundary cases where manikins with extreme but likely measurement combinations are derived by mathematical treatment of anthropometric data. The supposition by that method is that the use of these manikins will facilitate accommodation of the expected part of the total, less extreme, population. In literature sources there are differences in how many and in what way these manikins should be defined. A similar field to the boundary case method is the use of experimental design in where relationships between affecting factors of a process is studied by a systematic approach. This paper examines the possibilities to adopt methodology used in experimental design to define a group of manikins. Different experimental designs were adopted to be used together with a confidence region and its axes. The result from the study shows that it is possible to adapt the methodology of experimental design when creating groups of manikins. The size of these groups of manikins depends heavily on the number of key measurements but also on the type of chosen experimental design.

Applying cognitive science to digital human modelling for user centred design

To build software which, at the press of a button, can tell you what cognition-related hazards there are within an environment or a task, is probably well into the future if it is possible at all. However, incorporating existing tools such as task analysis tools, interface design guidelines and information about general cognitive limitations in humans, could allow for greater evaluative options for cognitive ergonomics. The paper discusses previous approaches to the subject and suggests adding design and evaluative guiding in digital human modelling that will help a user with little or no knowledge of cognitive science to design and evaluate a human-product interaction scenario.