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Micro-visual
Servoing for Micro-assembly
CHEN Guoliang1 HUANG Xinhan2
WANG Min2
(1. School of Mechantronic Engineering, Wuhan University of Technology, Wuhan 430070;
2. Department of Control Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074)
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Abstract: The pose adjustment of manipulator led and controlled by micro-vision is deduced for the problem how to make three points on its end-effector move for three set points in three-dimensional space respectively. A move planning is designed to avoid the collision and intervention of parts and to hold the end-effector in the visual field of the microscope, which stipulates one point moving along a line to its goal position and the other two points moving to their respective goal positions by rotating on the first point. According to this planning, a method based on the distance and angle between lines is proposed to estimate the image feature deviation, and the image Jacobian and kinematic model of manipulator based on the image feature are defined and built. An optimal control algorithm for the system with image delay is derived by the minimization of a cost function that allows weights to be placed on the error of the image features and the control signal. A micro-visual servoing control structure is designed to improve the positional accuracy, which includes a proportional controller and an optimal controller. The switch between the two controllers is selected by an error switch. Using a six-degree micromanipulator, experiments for adjusting line pose and tracking a moving target are performed to validate these researches. The results demonstrate that these researches are feasible and correct, and the location error is less than 2 pixels, which can satisfy the needs of the micro assembly.
Key words: Micro-visual servoing Micro-assembly Image Jacobian Optimal control
CLC No:
TP242.2
国家高技术研究发展计划资助项目(863计划，2006AA844120).
Received
20070308,
received
in
revised
form
20070915
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