A flexible fixtureless assembly of T-joint frame structures

This paper presents a new flexible fixtureless assembly (FFA) approach for building T-joint structures automatically. The method is based on a Fixturing Assistive Gripper (FAG) mounted on a robot arm for forming T-joint sections. It eliminates possible uncertainties in terms of positioning and size errors during fit-up process. The method is verified by a robotic assembly workcell which includes dual robots and a simple machine vision unit. The basic algorithms for image processing, task planning, dual robot cooperative motion and path planning are developed for assembling a simple structure which predominantly formed by T-joint sections. Experiments show that the workcell can effectively eliminate the alignment error and successfully complete T-joint assembly task without the complicated sensing system typically required in the existing approaches.