Combining safety and speed in collaborative assembly systems – An approach to time optimal trajectories for collaborative robots

Abstract Human-robot interaction is a key enabling technology of Industry 4.0 and the prospected pervasiveness of robotics in industrial environments will be not possible without enabling them to safety interact with humans. Such a fact imposes a relevant constraints because the limits imposed by the actual technical deliverables entail strong requirements in the operational velocity of robots when sharing their workspace with humans. In this paper, we address the theoretical limits of velocity under the light of current state-of-the-art trajectory planning and normative requirements. The main goal is to find a methodology to plan safe trajectories without neglecting cognitive ergonomics and production efficiency aspects. We start by considering the set of trajectories which are optimal with respect to a cognitive criteria and give a suitable parametrization to it. Then we are able to formulate the safety requirements in terms of constraints in an optimization problem. Finally, experimental results are provided. This allow the identification of the preferable sets of possible motions which satisfy the operator psychological wellbeing and the assembly process performance by complying the safety requirements in terms of mechanical risk prevention.