Manual tasks real-time ergonomic evaluation for collaborative robotics

In manufacturing, ergonomic and productivity benefits may result from combining the sensing and dexterity of the human workers with the strength of collaborative robots (cobots). Anyway, manual tasks requiring repetitive motion or working with robots can cause musculoskeletal disorders especially of the hands. In such a context, this paper proposes a novel solution that includes both a full body inertial system and a dedicated solution for hand tracking. This allows implementing the standard methods for assessing ergonomic indexes and to introduce new advanced task analyses based on gesture evaluation. The benefits reached by the integrated system for body and hand tracking can be exploited in the virtual prototyping of collaborative workstation in the manufacturing domain. Different software packages have been considered to model and simulate the collaboration between the operator and the cobot. In particular, Unity and ROS are used to develop the virtual scene and control the cobot behavior and the HTC Vive Head Mounted Display (HMD) to interact with the virtual environment. Physical ergonomics is evaluated by using both a full body suit (XSENS) and ensorized gloves (MANUS). The solution has been applied to the simulation of a virtual production line where the operator collaborates with a six-axis cobot (NIRYO ONE). Test tasks require the operator to move and manage different objects and tools by simulating different types of grasping. Real-time feedback about ergonomics, in terms of posture evaluation and alerts in case of critical condition, is shown to the operator as well as the automatic generation of reports for the post-process evaluation of the entire process. The results show how the use of these tools can be effective in the ergonomic evaluation of a collaborative robotic workstation which requires manual tasks.