Automatic identification of available grasping and fixturing surfaces in assembly resources planning

This paper describes a model enabling the identification of possible grasping and fixturing surfaces of the subassemblies involved at each step in an assembly sequence. Identification of such surfaces is challenging as it represents a dynamic process. That is, at one step of the assembly sequence, identified surfaces on some parts or subassemblies are different from those identified on the same parts or subassemblies at previous (or next) steps. Still, this kind of information is crucial in the design of efficient assembly resources, such as grippers and fixtures, used in the assembly line or cell. The model uses as input the product disassembly sequences, containing such information as the parts or subassemblies involved at each step and the disassembly directions at each step. To identify potential surfaces, reasoning is performed on a modified CAD model of the product. That is, the approach introduces new information in the CAD model, namely; elementary contact surfaces (FEc), void surfaces (FP), contact surfaces (FC) and free surfaces (FD). This classification approach helps filtering the surfaces on a geometric and technological basis, enabling the resource designer to focus only on the interesting ones for gripper or fixture design