A measurement strategy and an error-compensation model for the on-machine laser measurement of large-scale free-form surfaces

2013 ◽  
Vol 25 (1) ◽  
pp. 015204 ◽  
Author(s):  
Bin Li ◽  
Feng Li ◽  
Hongqi Liu ◽  
Hui Cai ◽  
Xinyong Mao ◽  
...  
Keyword(s):  
Error Compensation ◽  
Large Scale ◽  
Free Form ◽  
Laser Measurement ◽  
Scale Free ◽  
Compensation Model ◽  
Measurement Strategy ◽  
Free Form Surfaces

PB-Spline Hybrid Surface Fitting Technique

2009 ◽  
Author(s):  
Antonio Carminelli ◽  
Giuseppe Catania
Keyword(s):  
Large Scale ◽  
Free Form ◽  
Rectangular Array ◽  
B Spline ◽  
Large Scale Data ◽  
Spline Surface ◽  
Spline Basis ◽  
Data Points ◽  
Free Form Surfaces ◽  
Scale Data

This work considers the fitting of data points organized in a rectangular array to parametric spline surfaces. Point Based (PB) splines, a generalization of tensor product splines, are adopted. The basic idea of this paper is to fit large scale data with a tensorial B-spline surface and to refine the surface until a specified tolerance is met. Since some isolated domains exceeding tolerance may result, detail features on these domains are modeled by a tensorial B-spline basis with a finer resolution, superimposed by employing the PB-spline approach. The present method leads to an efficient model of free form surfaces, since both large scale data and local geometrical details can be efficiently fitted. Two application examples are presented. The first one concerns the fitting of a set of data points sampled from an interior car trim with a central geometrical detail. The second one refers to the modification of the tensorial B-spline surface representation of a mould in order to create a local adjustment. Considerations regarding strengths and limits of the approach then follow.

Software Dedicated to Determining a Strategy of Coordinate Measurements

2019 ◽  
Vol 957 ◽  
pp. 179-186
Author(s):  
Marek Magdziak ◽  
Dominika Ziaja
Keyword(s):  
Free Form ◽  
Coordinate Measuring Machines ◽  
Machining Processes ◽  
Matlab Software ◽  
Measurement Strategy ◽  
Coordinate Measurements ◽  
Free Form Surfaces ◽  
Cam Software

The paper presents the developed software dedicated to determining a measurement strategy of contact coordinate measurements conducted by using coordinate measuring machines. The created software enables to calculate locations of the scanning lines along free-form surfaces of measured workpieces. The presented program was developed by using the MATLAB software. The created program was tested based on the selected examples of curvilinear surfaces. Measurement points were located in the parts of surfaces characterized by the biggest form deviations resulting from machining processes. The calculated deviations were the results of simulations performed by using selected CAM software. The presented software increases the efficiency of measurement processes.

LARGE-SCALE FREE-FORM TIMBER GRID SHELL:

2020 ◽  
pp. 210-217
Author(s):  
HANNO STEHLING ◽  
FABIAN SCHEURER ◽  
SYLVAIN USAI
Keyword(s):  
Large Scale ◽  
Free Form ◽  
Scale Free ◽  
Grid Shell

The influence of a number of points on results of measurements of a turbine blade

2017 ◽  
Vol 89 (6) ◽  
pp. 953-959 ◽  
Author(s):  
Marek Magdziak
Keyword(s):  
Turbine Blades ◽  
Measuring System ◽  
Free Form ◽  
Experimental Investigations ◽  
Content Type ◽  
Measurement Strategy ◽  
Accuracy Of Measurements ◽  
Uncertainty Of Measurements ◽  
Measuring Machine ◽  
Free Form Surfaces

Purpose The purpose of this paper was to determine the influence of a number of measured points on results of measurements of turbine blades, which are the parts of aircraft engines. The selection of a number of points is the part of a measurement strategy in the coordinate measuring technique and determines the accuracy of measurements. Design/methodology/approach Numerical and experimental investigations were conducted. The measurements were simulated using different numbers of measured points. The simulated measurements were performed for the selected dispersion of measured points. The dispersion reflected the inaccuracy of a manufacturing process of the considered product and the uncertainty of measurements of curvilinear surfaces. To verify the accuracy of the numerical studies, experimental research was conducted. The real measurements were conducted using the selected coordinate measuring machine. Findings The gained results following the simulations can be very useful when selecting the appropriate number of measured points. The chosen number of points may be used during real measurements of turbine blades conducted on coordinate measuring machines. The results of numerical research indicate that there should be used the average radii of leading and trailing edges to increase the accuracy of measurements. The results of real coordinate measurements confirmed the results of simulation studies. Originality/value The main novelty of the paper is the presented methodology for determining the influence of measured points on results of measurements. The presented methodology helps the user of a coordinate measuring system select the appropriate measurement strategy of free-form surfaces applied in the aerospace industry.

Data Registration Method Based on Three Dimensional Target

2011 ◽  
Vol 103 ◽  
pp. 87-91
Author(s):  
Xiao Ping Lou ◽  
Nai Guang Lv ◽  
Peng Sun ◽  
Yi Min Lin
Keyword(s):  
Large Scale ◽  
Vision System ◽  
Three Dimensional ◽  
Optimization Methods ◽  
Free Form ◽  
Registration Method ◽  
Scale Free ◽  
Optical Scanning ◽  
Data Registration ◽  
Processing Steps

Data registration method using special three dimensional target to track the structured light measurement system is discussed. Optical scanning device, tracking target and stereo vision system are integrated together to fulfill profile inspection of large-scale free-form surface objects without extra mark points. System architecture and processing steps are introduced and layout optimization methods of three dimensional target are illustrated. Experimental results are showed to evaluate the validity of the registration method and suggests are given to improve the accuracy of the system.

scholarly journals Automatic Error Compensation for Free-Form Surfaces by Using On-Machine Measurement Data

2019 ◽  
Vol 9 (15) ◽  
pp. 3073 ◽  
Author(s):  
Wei-chen Lee ◽  
Yu-tzu Lee ◽  
Ching-Chih Wei
Keyword(s):  
Error Compensation ◽  
Tool Path ◽  
Substantial Reduction ◽  
Measurement Data ◽  
Compensation Method ◽  
Numerical Control ◽  
Free Form ◽  
Machining Errors ◽  
Free Form Surfaces ◽  
Finishing Machining

Currently, most computer numerical control (CNC) controllers lack the function needed to compensate machining errors for free-form surfaces. The objective of this research was to enhance the accuracy and precision of the machined free-form surfaces of a workpiece using the mirror compensation method with the on-measurement data. By mirroring the points measured after semi-finishing, a new free-form surface for finishing machining can be automatically reconstructed. The surface can then be used to generate the cutting tool path to reduce the errors during finishing machining. In this research, three different types of surfaces were used for evaluating the proposed method. The results show that the proposed method reduced the standard deviations of the three surface geometries by 61%, 61%, and 32%, respectively. We also evaluated the tool radius modification method commonly used in the industry for error compensation and found that there is no substantial reduction on standard deviation. Therefore, the effectiveness of the error compensation method proposed in this research is evident.

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