Abstract
The reduction of physical barriers between humans and robots has been accelerated in recent years by advancements in industrial robotics and sensor technologies. To ensure safety in human-robot interaction (HRI), various collaborative operations can be implemented according to recent standards and deliverables. This paper presents a review of recent research and progress on HRI, related to the available collaborative operations with emphasis on human safety. The current state of research and technology regarding speed and separation monitoring, power and force limiting as well as the combination of both collaborative operations is analysed in detail.