The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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System Usability of Complex Technical Systems
Teppo Tossavainen
Dissertation for the degree of Doctor of Technology to be presented with due permission for public examination and debate at Spektri in the Luna Auditorium at the Helsinki University of Technology (Espoo, Finland) on the 10th of May, 2002, at 12 o'clock noon.
Dissertation in PDF format (ISBN 951-22-5896-X) [2407 KB]
Dissertation is also available in print (ISBN 951-666-597-7)
Abstract
The system-wide usability of complex technical systems and particularly the complexity approach is not very visible in usability literature. The reason might be that the usability theories were originally created for computer systems, and ever since this user interface oriented approach has been used regardless of the industry. In this research, the system usability of complex technical systems is comprehensively studied in the case of a cellular network (GSM) by utilising complex system theory, biology, control theory and usability.
In the theoretical framework, we study complex technical systems by viewing literature of complexity research and biology, as well as apply the theories to technological evolution. We study how complexity has been defined and how to reduce user-observable complexity. Following this, we introduce the concept of fitness landscapes and the NK model in engineering in order to study technical coevolution in multiple system cases. Fitness landscape is a useful model, as the product development can be considered as constant hill climbing in a dynamic, ever-changing landscape, where the moves are made by selecting different feature combinations for the product from a vast solution space. By examining technical coevolution in dynamic fitness landscapes, we also see how error and complexity catastrophes arise when the complexity of the product exceeds a certain limit.
The empirical research concentrates on cellular telephone networks by studying the system usability of the networks from the operator's point of view. The empirical results are combined with the theoretical aspects to create new insight for system usability of complex hi-tech products. The construction explains how hi-tech companies live in coevolution with each other and external forces, in this way moulding each other's adaptive landscapes. We also give a definition for system usability with the aid of the effort the users must exert when deploying the system. By using this definition, the system usability of different technical systems could be measured and compared. Finally, we give some guidelines for improving system usability when designing complex technical systems. Good understanding of the described phenomena together with system usability expertise improves the chances of a hi-tech company in developing complex technical systems.
Keywords: usability, system usability, complex technical systems, cellular telephone networks, wireless networks, technical fitness landscapes, technical coevolution
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© 2002 Helsinki University of Technology
Last update 2011-05-26