Dynamic Projection of Human Motion for Safe and Efficient Human-Robot Collaboration

In the modern manufacturing process, novel technologies enable the collaboration between humans and robots, which increases productivity while keeping flexibility. However, these technologies also lead to new challenges, e.g., maximization of Human-Robot Collaboration (HRC) performance while ensuring safety for the human being in fenceless robot applications. In this paper, an approach of the dynamic human motion projection is proposed for typical assembly tasks. The human upper body is simplified as a five-degree-of-freedom (5DOF) rigid-body model. A control-oriented projection model is proposed, and its parameters are estimated from the test data of human capability. Combined with a human-state estimator and a collision estimator, the "worst-case" collision motion is projected in the HRC scenario. The dynamic projection method is feasible online. Finally, the estimated collision time is adopted to increase the robot’s speed limit, which validates the improvement of HRC’s efficiency.