A robotic Hi-Lite Bolts/collars assembly system and control strategy

Hi-Lite Bolts are widely used in the mechanical connection of composites in aircraft assembly. In this paper, we present a robot system based on an industrial robot, which can achieve the automatic assembly process of Hi-Lite Bolts to ameliorate the efficiency and improve the quality, as well as the intelligence of composite material assembly. A novel end-effector integrating the six-axis force sensor and direct-drive servo motor is designed to be installed on the end of robot in this system. In order to complete the alignment in small error region of bolt and nut and the twist-off of nut in the assembly process, we analyze the installation characteristics of the Hi-Lite Bolts and study the control algorithm based on force feedback to propose a control strategy for automatic connection of the Hi-Lite Bolts. A series of experiments are conducted at the end of this paper to demonstrate that the robot system is efficient and the control strategy is feasible.