STUDY OF VISUAL SERVOING FOR VIRTUAL MICROASSEMBLY BASED ON SOLID MODEL

Xi Wenming  Yao Bin  Wang Lei

(Department of Mechanical Engineering, Xiamen University, Xiamen 361005)

Zhu Jianying

(College of Mechanical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016)

Abstract: The major obstacles encountered in microassembly are that the to-be-assembled objects are very small in size and thus strict precision on assembly is required. Usually a microscope is used as a visual sensor to control the assembling movement. Under high magnitude of resolution and amplification, the viewing field and focal depth are too small and too short to allow the objects and tools become focused within the same focal plane at the same time, resulting in the blurred images, therefore the microscope fails to accomplishes the expected task. The focus theory of microscope is exploited fully to obtain the three dimension information of object and tool to constitute a solid model, the microassembly is carried out in virtual environment, object and tool in reality environments serve to check the correspondence between virtual microassembly and the changes in reality. When there are no changes in the objects and tool, virtual environment is kept stable, upon the changes in the objects and tool, virtual environment become reconstituted. Our results on experimentation and simulation show that virtual microassembly approach helps to avoid the defocus problem under the microscope and also to make the operation feasible and easier.

Key words: Solid model  Virtual microassembly  Visual servoing  Focus  Visual jacobian mapping

CLC No: TP24

国家自然科学基金(50275078)资助项目. Received 20040426, received in revised form 20040925