On the improvement of the combination of Power and Force Limiting and Speed and Separation Monitoring for an effective Human Robot Collaboration

In industrial human-robot collaborative tasks it is of paramount importance to guarantee safety, productivity and fluency. To this scope, beyond the two collaborative modalities introduced by the ISO/TS 15066 (Speed and Separation Monitoring - SSM and Power and Force Limiting - PFL), a modality that combines SSM and PFL to further enhance productivity of a collaborative task has been proposed in literature. However, such method, while guaranteeing an improvement with respect to the two modalities foreseen by the ISO/TS 15066, relies on some conservative assumptions that limit its potentialities. In this work, a method to overcome these limitations is presented and its effectiveness is validated through numerical simulations. Results show that the novelty introduced in this paper leads to an improvement in terms of productivity, fluency of the operation and in usage of the robot, without affecting the safety of the collaborative tasks.