Towards safety level definition based on the HRN approach for industrial robots in collaborative activities

Abstract

Since the first industrial revolution, factories seek to increase their profits by improving their performance and reducing costs in their products. With each new industrial revolution, new ideas on how to reduce costs appear. Currently, in industry 4.0, the fourth industrial revolution, advanced robotics emerges as one of the principal pillars and with-it collaborative robotics. Collaborative robotics is the branch of robotics that has the security systems needed to perform joint activities with humans. However, the quantification of safety level varies depending on the location and more granularly from company to company. This work aims to assign levels of safety that allow a robot to perform a collaborative activity. To propose such values, the work was started with a bibliographical review focused on defining the robots that would be approached, reviewing the ISO (International Organization for Standardization) related to machinery safety and defining the term of collaboration. Then, the method of calculation of the safety indicator was evaluated, in the case covered was the Hazard Rating Number (HRN), and then defined the intervals that will be assigned to the robots that will perform collaborative activities. To validate the defined HRN intervals, a survey was developed and distributed for engineers from automation sector of an automotive company trained in safety, in this survey, categories of robots were placed for the engineers to assign HRN values to them. After the survey, the results were grouped and analyzed analytically. As a result, the proposed HRN intervals were validated because they fit the safety-level stipulated required for a robot to perform collaborative activity. Also, it was concluded that a robot can perform a collaborative activities even if it has not been acquired for this purpose, it is enough that it meets the safety requirements proposed in the work.