A Digital Twin-based Workspace Monitoring System for Safe Human-Robot Collaboration

Human-Robot Collaboration (HRC) requires rigorous safety standards to ensure the safety of the operator. To this end, one promising approach is to install safety-rated sensors in the workcell while considering collaboration methods such as the Safety-rated Monitored Stop (SMS) and Speed and Separation Monitoring (SSM). This paper proposes a Digital Twin (DT)-based workspace monitoring system to implement the approach for safe HRC with both industrial robots (IRs) and collaborative robots (cobots). In the DT framework, the pose of the operator is provided by laser scanners and a body-tracking camera, and the sensor data are processed to calculate the distance between the operator and the hazardous area in order to control the speed of the robots. We carry out experiments to demonstrate the speed scaling function of robots, and the results show that robots can dynamically adapt their movements according to the distance to guarantee a safe environment.