The Plug‑In project, funded by the Federal Ministry of Education and Research (BMBF) and carried out from 1 March 2020 to 31 May 2023, aimed to replace the traditional “one‑size‑fits‑all” user interface paradigm for household appliances with a self‑adaptive, personalised interface that grows with the user. The Technical University of Georg Agricola led the effort, working in a consortium that included the Fachhochschule Dortmund and several other research institutions. The consortium’s interdisciplinary composition—combining human‑computer interaction, software engineering, cognitive science and ethics—enabled a holistic approach to interface design and evaluation.

The project was organised into seven work packages. In the initial requirement analysis (AP 1) contextual inquiry was used to observe users in their homes while operating appliances. This method allowed participants to articulate their needs and problems directly, producing a rich set of functional and usability requirements that were shared with the entire consortium. User participation continued throughout the project (AP 2), with three workshops that focused on UI/UX design, data transparency, ethical, legal and social implications (ELSI) and final prototype testing. The workshops fed back into the design cycle, ensuring that user preferences remained central.

Building on the gathered data, the team developed a set of personas and use‑case scenarios (AP 4) that captured typical user profiles, including those with visual impairments. These personas guided the design of adaptive features such as automatic font‑size adjustment when a decline in visual acuity was detected. The interface building kit (AP 5) incorporated all identified elements, allowing designers to assemble interfaces that matched the specific needs of each persona. A style guide (AP 6) defined colours, shapes, typography and element sizes, providing a consistent visual language that could be reused across devices.

The final design study (AP 7) produced functional prototypes that were iteratively refined and evaluated in the user workshops. The prototypes demonstrated that personalised interfaces could be generated automatically based on contextual information—user preferences, behaviour patterns and environmental data—without compromising usability. While the report does not provide quantitative performance metrics, the repeated successful testing and refinement cycles indicate that the prototypes met the usability criteria set out in the early requirement analysis.

Collaboration within the consortium was a key factor in the project’s success. Each partner contributed specialised expertise: the Technical University of Georg Agricola led the overall coordination and the development of the interface building kit; the Fachhochschule Dortmund provided expertise in user modelling and adaptive algorithms; other partners supplied domain knowledge on specific appliances and contributed to the ethical assessment of the system. The pandemic‑induced shift to remote collaboration actually strengthened the interdisciplinary dialogue, as virtual meetings and shared digital artefacts facilitated continuous feedback across all partners.

In summary, the Plug‑In project delivered a functional, self‑adaptive interface platform that can be customised to individual users’ needs and preferences. Through a rigorous mixed‑methods approach, continuous user involvement, and close collaboration among academic partners, the project produced prototypes that demonstrate the feasibility of moving beyond the one‑size‑fits‑all paradigm in domestic appliance interfaces. The work lays a foundation for future research and development of assistive technologies that support independent living across the lifespan.