Assembly Task Allocation for Human–Robot Collaboration Considering Stability and Assembly Complexity

This paper proposed a task allocation method for human-robot collaborative assembly from a graphical instruction manual based on the assembly complexity while considering the stability of each sub-assembly task. Without using the CAD model of each part to construct the liaison graph, we generate the liaison graph of a product from the 2D graphical instruction manual. To realize a successful assembly task, we especially focus on the support relation of parts considering the stability during the construction of each connection. We check the stability of each sub-assembly task and then decide the timing to add support to maintain stability and the agent to execute this support motion. In addition, to complete an assembly task with additional support motions by a human operator and a robot, other implicit motions need to be considered, such as the direction change of the subassembly and the tool change motion, which is necessary to execute the planned task sequences. The dynamic liaison complexity for each sub-assembly is computed separately for the human operator and the robot to assign different sub-assembly tasks to appropriate operators. The allocation result is sent to a human-centered HRC interface to realize the communication between human operators and robots during the assembly task. Four chairs from different manufacturers are used to evaluate the effectiveness of the proposed allocation method. Finally, a human operator and a dual-arm robot collaborate to accomplish two chair assembly tasks.