A resource-oriented tolerance representation scheme for the planning of robotic machine tending operations in automated manufacturing systems

Abstract

In this paper, we define a representation for tolerances associated with robotic machine tending operations. The intent of the representation and analysis presented in the paper is to assess whether a robotic material handler is capable of holding the accuracies required for loading and unloading a machine. This representation and analysis, therefore, provides the basis of a process planning system for robotic operations. This representation is critical for flexible and automated manufacturing because it enables automatic planning of unload and load operations from and to machining centers that are required for discrete part manufacturing. Planners can use this representation along with the specified tolerance criteria to conservatively assess if a given robot resource is capable of using a specific gripper to unload or load a given part from a given fixture on a machining center. For a new part, this assessment allows an automatic material handling operations planner to determine if reconfiguration or procurement of resources is required for the material handing of the new part or if simple reprogramming of the robot and machine resources is sufficient. Also, this representation helps providing flexibility to the manufacturing system control software in the case of the addition of a new machine to the manufacturing system. In this case, the new resource data would be input into the resource model, and the decision on the machine tending operations (loading or unloading) would be carried out in the same manner. This representation was tested successfully using an automatic operations planner at The Pennsylvania State University’s Factory for Advanced Manufacturing Education (FAME) lab.