A good adjustable control system is a system that can adapt its behaviors according to the user's state over time. While most researches in Human-Robot Cooperation focus on making the robotic system more efficient and effective in task accomplishment, we argue that very few works tried to model the human operator. In this paper, we discuss several aspects related to the human operator that we consider important for an efficient Human-Robot Cooperation. Furthermore, we present a tentative architecture of an adjustable control system, where these aspects are emphasized.