Preguntas específicas.

The system developed in this study can be regarded as an interactive guideline for human simulation analyses, since it presents the methodology of using human simulation tools and guides the user through the process as well as documenting the simulation results in a database. This corresponds to the need identified by Green (2000) for a structured human simulation process and the system assists the tool user to follow an appropriate process without necessarily recognising it, as discussed by Rouse and Boff (1998).

University users tended to be more positive than industry users, and the industry users tended to be more positive than the managers. However, some of the university users had been involved in researching these kinds of issues themselves, which could explain their more positive attitude to the formalised process.

The acceptance rating of the human simulation support system is lower than the ratings for all other usability characteristics. This could be explained by the subjects' comments on rather extensive documentation, and also that some found it difficult to fill in the requested information. The use of the formalised process is likely to reduce differences in results, both within and between tool users, as well as document the employed process and deliver well-founded and consistent results.

Today, human simulation tool users tend to have a vague picture of the tasks that the driver or assembler performs (as discussed in Section 4.2). In many cases the tool users have neither performed the tasks they simulate nor seen them being performed. It is recommended that human simulation tool users should gain their own experience and understanding of the tasks they are simulating. This could be arranged by such activities as simulation engineering days at assembly plants or days for test-driving concept cars, which would prepare the tool users for theoretical task analyses. Furthermore, for effective use, understanding of a human simulation tool's capabilities and limitations are important. The system developed may not enhance tool users' understanding; therefore prior knowledge of the tool is essential. However, the use of the system may establish and increase confidence in human simulation tools within the company group and be one way of changing the negative attitudes towards ergonomics which, according to the study by Helander (1999), frequently is considered to be simply a matter of common sense.

A formal process description can also support new tool users when performing analyses and in speeding up the learning process. Competence and awareness of tool limitations may increase with a formal process, leading to a reduced number of misuses. Furthermore, with a formal process it may be possible to let non-experts, e.g. 'ordinary' designers, perform simple standard analyses, i.e. a move towards making human simulation tools become 'designers tools' (in line with Hypothesis 2), and to let the tool experts act as supervisors and/or consultants. An increase in the number of users is likely to spread awareness and knowledge about ergonomics and usability. The information documented in a database could support professionals as well as beginners and maintain the knowledge as a common resource instead of as an individual one. This is important, e.g. since the automotive industry frequently applies job rotation to promote career advancement, either inside or outside the organisation.

Today, human simulation tools are used by a few users working in isolated departments within a company, with a limited dialogue between departments. The previous case study (Section 4.2) showed that this particularly was the case between product and production development departments. However, there are great similarities between the issues analysed with human simulation tools. By bringing the people working with human simulation together in the organisation, a critical mass can be achieved; something that was also requested in the evaluation of the system. A forum could be established as a channel for sharing tools, experience and knowledge, which is likely to increase the aggregate human simulation competence in the organisation. At a

higher level, this is likely to improve product quality and reduce product development time. The formal process may be a common interest that is needed to start a forum where human simulation tool users can discuss findings, problems and possibilities. The system could also facilitate exchanges of experiences and information between users within the company as well as between companies in the company group. The use of a common human simulation process and cooperation between company group members may lead to efficient cooperative human simulation work. European tool users can analyse a request sent late in the afternoon from the US and vice versa. Such a process may facilitate fast replies and reduce work peaks for human simulation tool users, thus facilitating a smooth and efficient vehicle design process.

Development and use of a database that keeps track of previous and ongoing

analyses facilitates the tracing and reuse of analyses. With experienced and educated tool users and a complete human simulation system, consisting of a process, a tool and a database, it may be possible to reduce the number of physical prototypes required in the development process, something which is very attractive from time and cost

perspectives, particularly in vehicle development companies.

4.4. Summary

The aim of the chapter was to analyse how computer aided ergonomics may support integration of ergonomics in design processes.

Since human simulation tools enable ergonomics evaluation of a design during virtual stages, ergonomics can be considered in a way that is similar to the way that other product requirements are assessed and it is possible to reduce the ergonomics

deficiencies when the product is eventually physically realised.

Since CAD is a widespread tool for today's designers it is sensible to see CAD as a means for supporting user aspects consideration, i.e. in making the CAD system the vehicle for ergonomics input. By aiding designers to see the entire human-product interaction, human simulation tools, ideally integrated in a CAD system, can be a common tool as well as acting as a communicator of ergonomics issues within design teams, thereby supporting integrated work. By offering human simulation tools as part of the designers' package of CAD tools it becomes 'their' tool and it signals the importance of integrating ergonomics, and as being a 'normal' issue to consider when designing products. This approach involves risks of misuse though, and it puts pressure on human simulation tool developers to adapt the tools to designers' requirements.

The developed support system for human simulation can act as an interactive guideline for human simulation analyses, both for requesting, performing and interpreting

simulations. Since the system presents the methodology of using human simulation tools and guides the user through the process, as well as documenting the simulation results in a database, it becomes easier for the tool user to follow an approved process as well as take advantage of experiences of previous simulations, even though not familiar with all methodological details behind the system and the proposed process. As a result, the support system backs up Hypothesis 2 since it encourages the outlook of 'normal' designers utilising human simulation tools. By supporting communication among members in a product development team and acting as a vehicle for discussing findings, problems and possibilities about ergonomics and human simulation, the support system also backs up Hypothesis 1.

As discussed, it is important that the manikins used in human simulation represent the targeted product users. Since humans show large variations in body size and proportions, this area is not as straightforward as one may assume. The next chapter focuses on how to handle this complexity in product design by the use of manikin families in human simulation tools.