Converting maintenance actions into standard symbols for Augmented Reality applications in Industry 4.0

The evolution of technical documentation in the age of Industry 4.0 is going towards the use of visual manuals, in particular exploiting Augmented Reality (AR) technology. Traditional manuals are rich of text instructions that in AR applications are not advisable. In fact text occludes the real scene behind and it is an issue for the translation. For this reason, we propose to create and adopt a controlled and exhaustive vocabulary of graphical symbols, to be used in AR to represent maintenance instructions. In particular, in this work we identified the most frequent maintenance actions used in manuals, and converted them into graphical symbols. Then, we made an elicitation of the symbols designed and created different candidate vocabularies of symbols basing on the criteria found in literature of guessability and homogeneity. Moreover, the vocabularies had to respect two constraints: conflict set and reversibility. Finally, we identified the best of symbols and integrated this one in a real AR application for remote maintenance.