This paper deals with the challenge of knowledge reuse and its adaptability to each activity context in the working environment. The scientific work focuses on the context idea as defined by the ubiquitous computing paradigm. The purpose of this approach consists of conceptual models design allowing knowledge structuration according to multiple completeness scales. The proposed approach allows the management of contextual information in a knowledge-based system. A prototype has been implemented to demonstrate the industrial feasibility and the contextual task assistance tool is called “Digital Factory Assistant”. The Assistant is dedicated to production line workers and can also be applied in design context.