An image mosaic technique with non-overlapping regions based on microscopic vision in precision assembly

Abstract

Microscopic vision has been widely applied in precision assembly. To achieve sufficiently high resolution in measurements for precision assembly when the sizes of the parts involved exceed the field of view of the vision system, an image mosaic technique must be used. In this paper, a method for constructing an image mosaic with non-overlapping areas with enhanced efficiency is proposed. First, an image mosaic model for the part is created using a geometric model of the measurement system installed on a X-Y-Z precision stages with high repeatability, and a path for image acquisition is established. Second, images are captured along the same path for a specified calibration plate, and an entire image is formed based on the given model. The measurement results obtained from the specified calibration plate are utilized to identify mosaic errors and apply compensation for the part requiring measurement. Experimental results show that the maximum error is less than 4 μm for a camera with pixel equivalent 2.46 μm, thereby demonstrating the accuracy of the proposed method. This image mosaic technique with non-overlapping regions can simplify image acquisition and reduce the workload involved in constructing an image mosaic.