Modern design of human/machine interfaces requires a better understanding of how operators control their interaction with machines. To understand these interactions, cognitive ergonomists seek to construct cognitive models of operators. These models generally depict operator activity as a process of information- collecting, computing, decision-making, and action. While this symbolic approach effectively describes formal reasoning, it becomes ambiguous when con- sidering an activity in which operators are physically involved, such as driving a car. Here, operators’ cognitive process accompanies their actions and can be equally viewed as a cause or as a consequence of their activity. Perception, cognition, and action can hardly be separated, because expectations drive perception, and the feeling of comprehension relies on possibilities of action. Where interaction and perception are so tightly coupled, we take inspiration from psychologists like Piaget, who have proposed to keep perception and action embedded into schemes. We consider schemes and cognitive schemas as the basic elements of our cognitive modelling, and we seek to highlight and model them from “traces of activity” (Georgeon, 2008). To do this, we have implemented knowledge engineering software and a method of cognitive modeling, which derives from “traces of activity”. This software includes graph processing and visualization, symbolic inference, as well as ontology manipulation