光学显微定位系统定位精度分析

Positioning accuracy analysis of optical micropositioning system

为了提高光学显微定位系统对细胞微生物识别定位的精度:一方面,必须改进手眼标定方法;另一方面,需要提高全局图像识别的准确性,因此,提出一种两步法对系统进行手眼标定。首先,通过标定固定靶标来确定系统原点,并得到视觉模块相对于系统原点的转换关系;然后,根据每次拍照的起始点位置、拍照的数量和移动的步长求解出全局图像相对于系统原点的转换关系;最后,为了进一步提高全局转换关系的准确度,提出一种基于傅里叶变换的误差矫正方法,利用傅里叶变换求解出视觉模块在移动过程中的误差,并加入系统进行补偿。实验结果表明,误差补偿之后,系统X轴方向的误差均值从10.23μm降为-0.002μm,Y轴方向的误差均值从6.9μm降为-0.50μm,显微定位系统的平均定位精度达到了99%以上。结果表明,所提方法可很好地用于光学显微定位系统对细胞微生物进行高精度的自动化抓取。

In order to improve the accuracy of identification and localization of cell microorganisms by optical micropositioning system,on the one hand,the hand-eye calibration method should be optimized,on the other hand,the accuracy of global image recognition should be improved.Aiming at those,a two-step method for hand-eye calibration of the system was proposed.Firstly,the origin of the system was determined by calibrating the fixed target,and the transformation relationship of the vision module to the origin of the system was obtained.Then,according to the starting point position of each photograph,the number of photoing and the step size of movement,the transformation relationship of the global image to the origin of the system was solved.Finally,in order to further improve the accuracy of the global transformation relationship,an error correction method based on Fourier transform was used to obtain the error of the visual module in movement,then the error was added into the system for compensation.Experimental results show that after error compensation,the micropositioning system has the error mean value in X-axis direction reduced from 10.23 μm to-0.002 μm,the error mean value in Y-axis direction reduced from 6.9 μm to-0.50 μm,and the average positioning accuracy over 99%.The results show that the proposed method can be applied to the optical micropositioning system for high-precision automated capture of cell microorganisms.