Automatic Measurement And Assembly For Miniature Parts Based On Machine Vision

Because of advantages of small volume, low energy consumption and reliable performance, precise and miniature electromechanical products are widely used in the field of industry, military, biology. Involving different materials, processing and connection technology, this kind of products are not always manufactured for one time, but always are combined by miniature parts. Assembly is an important link in the manufacturing of this kind of products.The size of miniature parts is always between sub-millimeter and several millimeters, whose range is wide, the parts were also required to have a high assembly precision. At present, the precise assembly operation of miniature parts was mainly finished by experienced workers, this leaded to some problems, such as low produce efficiency, poor product uniformity, manual assembly needed high skills for workers .As the demand of the yield and product performance increased, it is hard for manual assembly to adapt to the development, the research on precise assembly automation was badly needed.Precise assembly for miniature parts based on machine vision has advantage of flexibility, it can realize automation of measurement and assembly in the assembly process for miniature parts, it is also an effective way for solving problems such as low efficiency of manual assembly, poor quality stability and improving qualified rate of products.The structure of assembly system based on machine vision for miniature parts was researched, the system was divided into four main function modules of precision measurement, assembly operation, worktable of feeding and human-computer interaction, among them, the module of precision measurement was consist of micro-vision system and high-precision motion platform, solving the contradictions with large span of part size and narrowness field of CCD camera when measuring accuracy and resolution were high required. On the base of the analysis of control strategy, software architecture was researched, the method of "Task Message" was used to control the task of measurement and assembly. the function of manual intervention was increased in the necessary assembly link in order to overcome the adverse effection of microminiaturization for parts.As an example, the assembly system for miniature shaft and hole parts was introduced, experiments showed that the structure, control strategy and software architecture that were used in the assembly system realized the required function, met the requirement of automatic measurement and precise assembly for miniature parts.