Automatic precision assembly system for trans-scale miniature parts

Abstract

An automated precision assembly system for the part with a trans-scale structure is developed in the paper. Based on the analysis of assembly task, the system uses a modular architecture, including computer control and human-machine interaction module, 3-DOF (Degree of Freedom) operation manipulator module, 1-DOF operation workstation module, 4-DOF visual measurement and screw assembly module, 1-DOF charging module and operation tool library module. According to the characteristics of the trans-scale part and assembly accuracy, the visual measurement module of this system is based on the Look and Move mode control strategy. To solve the problem of blind spot detection, the manipulator module is based on impedance control strategy to control the force of part assembly and the screw assembly module adopts the torque/time control method to realize the consistency of the pre-tightening force of the screw assembly. The results of assembly experiment for a miniature device show that the error of the coaxial degree is less than 13 μm and the parallelism degree is less than 10 μm. The assembly accuracy meets assembly requirements of miniature devices.