A Time-Optimal Energy Planner for Safe Human-Robot Collaboration

The human-robot collaboration scenarios are characterized by the presence of human operators and robots that work in close contact with each other. As a consequence, the safety regulations have been updated in order to provide guidelines on how to asses safety in these new scenarios. In particular, Power and Force Limiting (PFL) collaborative mode describes how the energy should be regulated during the collaboration. Based on these guidelines, we propose a new optimal trajectory planner which, by exploiting the variability of the robot's inertia as a function of its configuration, is able to return trajectories that can be travelled at greater speed and in less time, while guaranteeing the safety limits according to the standard. The proposed planner was validated first in simulation, comparing completion times with other state-of-the-art planning algorithms, and then experimentally, demonstrating the performance of the planned trajectories during physical interaction with the environment. Both validations confirm the effectiveness of the proposed planner, which returns shorter completion times while ensuring safe interaction.