A Formal Representation System for Modelling Assistive Technology Systems

This chapter describes a formal representation scheme which can be used to model Assistive Technology (AT) Systems. At the heart of any system is a conceptual model of domain of application. Where AT is involved, the conceptual model must embrace all the elements of AT systems which are defined as "consisting of an AT device, a human operator who has a disability and an environment in which the functional activity is to be carried out" (Cook and Hussey, 1995, 2002, 2007). In order to explore the interaction between the components of AT systems in dynamic simulations of AT deployment, there is a need for a suitable representation of the underlying concepts. While the representation scheme presented here is generally applicable, examples and issues to do with representing AT systems for those with motor limitations, in particular are considered. The proposed representation scheme uses Coloured Petri-Nets (CP-Nets) and is based on the WHO International Classification of Functioning (ICF). This chapter looks at how CP-Nets may be used to represent the elements of AT systems as described by Cook and Hussey. These are Person, Activity, AT and Context. Both informal and formal representations using CP-Nets are considered. The ICF is at the heart of the proposed formal representation scheme. Its effectiveness for this purpose is analysed. Enhancements and innovative approaches are offered where there are challenges presented in using the ICF.