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Point cloud data extraction is an important process in scan-tracking measurement. In this paper, a new method of on-line three-dimensional point cloud data extraction for scan-tracking measurement is proposed for reducing extremely dense sampled data while maintaining data accuracy during the real-time scan-tracking measuring process. It is inspired from sketch paintings: First outlining the broad contour of the curve and then revising local details till the interpolated curve satisfies the required accuracy. This method adopts bi-Akima spline interpolation for connecting acquired points in NC machining or for point data fitting in reverse engineering. It can reduce efficiently the amount of point data with a smaller data reduction ratio and a smoother machined/fitted surface than conventional three-dimensional chordal method. [ABSTRACT FROM AUTHOR]

Abstract: This paper is concerned with the optimal design of motion control for scan tracking measurement using Cerebellar Model Articulation Controller (CMAC) neural networks in order to improve the measuring efficiency while maintaining the measurement accuracy, and to achieve friction compensation. Aiming at the effect of geometric shape and material friction of the model surface on the precision and efficiency of scan tracking measurement, technologies of model surface geometric and friction feature identification and quantification are researched. A novel optimal motion controller for scan tracking measurement is designed and realized, which automatically predicts the surface features (including geometric feature and friction feature) and adjusts the scan tracking velocity in advance. The approach to friction quantification and compensation in measuring process is given specifically. Finally, through Matlab simulation experiments, the realizability and application effect of the studied optimal motion control method for scan tracking measurement are verified, and the measuring efficiency is increased by 123.33%. Simulation results show that the proposed motion controller is an effective way to enhance the measurement efficiency remarkably compared with the traditional control strategy. [Copyright &y& Elsevier]