A probabilistic approach to workspace sharing for human–robot cooperation in assembly tasks

Recently, human–robot cooperation (HRC) research activities have focused on the development of new methodologies for the generation of safe robot trajectories. However, the applicability of such methodologies in a real context is limited due to the inherent uncertainty of robot trajectory execution time (i.e. the robot can avoid the worker by modifying its velocity along the path). This paper proposes an approach to estimate a confidence interval on robot trajectory execution time for scenarios in which human–robot space sharing is required. First, human arm movements are studied for a given set of assembly collaborative tasks: worker occupancy volumes and occupancy volume probabilities are derived. Then, a finite number of alternative robot trajectories, crossing human occupancy volumes with different occupancy probabilities, are generated. It is therefore possible to estimate a probability for the robot to reduce its velocity, and a confidence interval on the robot execution time. The application on a real assembly case is discussed.