Integrating occlusion monitoring into human tracking for robot speed and separation monitoring

Collaborative robots are used in close proximity to humans to perform a variety of tasks, while more traditional industrial robots are required to be stopped whenever a human enters their work-volumes. Instead of relying on physical barriers or merely detecting when someone enters the area, the collaborative system must monitor the position of every person who enters the work space in time for the robot to react. The TC 184/SC 2/WG 3 Industrial Safety group within the International Organization for Standard(ISO) is developing the standards to help ensure collaborative robots operate safely. Collaborative robots require sophisticated sensing technologies that must handle dynamic interactions between the robot and the human. One potential safety risk is the occlusion of a safety sensor's field of view due to placement of objects or the movement of people in front of a safety sensor. In this situation the robot could shut down as soon as even a single sensor was partially occluded. Unfortunately this could greatly diminish the extent to which the robot could work collaboratively. In this paper we examine how a human tracking system using multiple laser line scanners [3]was adapted to work with a robot Speed and Separation Monitoring (SSM) safety system and further modified to include occlusion monitoring.