Automatic identification of the assembly base component for robotic manufacturing

Abstract

The base component of an assembly is the part placed on the worktable, and typically the part from which the assembly sequence starts. Automatically determining a base component suitable for robotic assembly is challenging since both assembly requirements and part handling requirements must be considered. However, automatically determining the base component is an important preliminary stage for automatic assembly sequence planning, which can considerably increase process efficiency. Prior work on automatic base component identification concentrated on the assembly requirements without specific regard to the requirements of robotic assembly. The current work integrates assembly requirements with robotic handling requirements. A two-stage algorithm for identifying a base component suitable for robotic assembly is presented. A geometric stage that addresses assembly requirements and is based on the geometric parameters of the parts extracted from a CAD model. A caging stage that addresses robotic assembly requirements assessing whether the parts can be caged by a standard vice. The algorithm was implemented with SolidWorks API and tested with ten assemblies with 2-8 parts each. The selections made by the algorithm were compared to selections made by process experts. The agreement between the experts and the algorithm was 77% and 90% for the geometric and caging stages respectively. The high agreement in the caging stage selection validates the suitability of the algorithm as a preliminary stage for automatic robotic assembly sequence determination.