Safety Evaluation in Human-Robot Collaboration Through Risk Assessment Matrix and Observational Measurements

Abstract

Manufacturing assembly activities are competing to be one of the most intriguing and promising applications in collaborative settings, accounting for about half of the typical workload in the real manufacturing process. Collaborative robots, or cobots, allow to enhance productivity and wellbeing in those manufacturing repetitive and tedious tasks. Hence, human robot-collaboration, named also HRC, activities have been recognized as one of the pivotal solutions to increase efficiency. However, safety considerations must be considered in the design of collaborative workplaces, where humans work alongside robots, as hazards arise. This paper highlights the design and implementation of a risk assessment matrix deployed for the implementation assessment of a cobot in a collaborative workplace. Two scenarios are defined in the modular assembly workstation set up in a laboratory environment: standard scenario-where participants accomplished an assembly task without any intervention-and collaborative scenario-where participants accomplished the same task working alongside the cobot. The cobot deployed for the collaborative activity is the industrial Melfa Assista Mitsubishi cobot, equipped with safety sensors and designed for collaborative tasks. Moreover, the choice of the gripper, the VGC10 Vacuum Gripper was crucial in the design of the collaborative task, considering safety aspects though. Finally, authors analyzed the productivity index through observational measurement and the quality of the task through questionnaires asked at the end of the tests to participants to further evaluate the level of efficiency of the task with the robot. Results showed a consinstent and significant increase of productivity in the collaborative scenario, highlighted by the statistical T-test analysis.