Adaptive Sampling of Digitizing for the Unknown Free-form Surface Based on Front Path Detecting

In order to realize high-efficiency and high-accuracy digital measurement unknown free-form surfaces in reverse engineering, an adaptive sampling method based on front path detecting is presented. The method is characterized by integration of one touch probe(TP) and two point laser probes(PLPs). The two PLPs are located on both sides of the TP. A coordinate transformation model is built to transform these three probes’ measurement results into a reference coordinate system. In the process of line-by-line sampling, at the measuring direction, the PLPs are used to detect the measuring path information in front of the TP, the data acquired by the PLPs is processed and fitted into B-splines instantaneously, and then the TP measuring path planning can be generated according to the curvature feature of the fitted B-splines. The obtained path detecting information is subsequently used to automatically guide the TP to achieve adaptive sampling. While at the cross-section intake direction, "cross-section angle" analysis algorithm is used to subdivide the cross-sections adaptively. Simulation and experiment results indicate that the sampling points generated by the TP are laid out rationally according to the curvature of the surfaces, and demonstrate that the sampling efficiency and accuracy can be improved significantly, and effective sampling data can be offered for reverse engineering.