| Summary: | 碩士 === 國立清華大學 === 動力機械工程學系 === 93 === The objective of this thesis is to develop a high-precision multi-axis laser scanning system for small workpieces, including a 4-axis laser scanning machine, a control system and data processing software. The workpiece can be moved by a rotary axis and linear stages according to designed paths. Therefore, the machine can digitizes the 3D profile of a workpiece by a single point laser head. The whole measuring precision is in μm scale which is higher than the existing products on the market. In addition, this thesis proposes a new data simplification algorithm and a new data registration procedure. The data simplification algorithm can remove inappropriate or unnecessary points by the direction of the concaves. For data registration, this paper proposes a new method named “Data Registration Based on Explicit Coordinate Transformation”. The method calculates the axial of the rotation axis and the offset between the reference coordinate and the workpiece coordinate by a standard ball in advance. Therefore, the actual positions of the measured points in workpiece coordinate can be calculated by the rotary angle and the Homogeneous Transformation Matrix (HTM). In other words, the measured points can be transformed to the same coordinate and the data registration can be made. The method can avoid a large amount of calculation and local optimal problem of the Iterative Closest Point (ICP) algorithm. Besides, the method not only can be used in the machine we developed in this thesis but also can apply to any machine tools with rotary axis to set up accurate transformation parameters, improving the precision of the machine by a wide margin.
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