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Adaptive sampling method based on machining error model and Hammersley sequence

A technology of adaptive sampling and processing error, applied in simulators, program control, instruments, etc., to avoid aliasing

Inactive Publication Date: 2018-05-04
TIANJIN UNIV
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  • Claims
  • Application Information

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Problems solved by technology

These methods have indeed improved the effectiveness and accuracy of detection, but the existing methods still have room for improvement

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  • Adaptive sampling method based on machining error model and Hammersley sequence
  • Adaptive sampling method based on machining error model and Hammersley sequence
  • Adaptive sampling method based on machining error model and Hammersley sequence

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Embodiment Construction

[0044] The present invention will be further described below in conjunction with the accompanying drawings.

[0045] About the Hammersley sequence

[0046] Generally, there are two ways to carry out inspection work: random sampling or regular sampling. However, random sampling results are uncertain. To avoid this, it is obvious that multiple measurements are required, which takes a lot of time. On the other hand, the problem with regular sampling is the aliasing phenomenon in the sampling process.

[0047] In the field of processing and measurement, using a three-coordinate measuring machine tool to inspect a free-form surface workpiece is a process of discretizing a continuous surface. Figure 1a with Figure 1b Schematic showing the aliasing phenomenon caused by regular sampling. The figure shows the results of the simplified theoretical profile of the surface and the regular sampling of the image isoparametric sampling applied thereto. obviously Figure 1a with Figur...

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Abstract

The present invention discloses an adaptive sampling method based on a machining error model and a Hammersley sequence. According to the method, the Hammersley sequence can be mapped to a discrete surface created based on a machining error model to determine the location of a sampling point. The method includes the steps of establishing a machining error model (MEM) of a curved surface according to a CAD model of the detected curved surface; determining the sampling quantity and generating a Hammersley sequence; adaptively discretizing the detected curve surface according to the MEM to obtainan adaptive discrete model of the detected curved surface; mapping the Hammersley sequence to the discrete surface created according to the MEM, and obtaining an adaptive sampling method based on themachining error model and the Hammersley sequence to guide the distribution of sampling points. According to the method, on the one hand, the MEM of the present invention can ensure that the samplingcan be closer to the distribution of processing errors. On the other hand, the two-dimensional Hammersley sequence can effectively avoid the occurrence of aliasing and can better capture an area having larger deviations on the machined surface.

Description

technical field [0001] The invention relates to the field of machining error measurement, in particular to an adaptive sampling method based on a machining error model and a Hammersley sequence. Background technique [0002] Free-form surfaces are widely used in engineering, and the complex geometric features of free-form surfaces pose great challenges to machine tools and detection methods. In the detection of free-form surfaces, the sampling process includes two parts: setting the number of sampling points and selecting the layout strategy of sampling points. However, the distribution of sample points is a major factor in determining the number of sample points in many cases. Therefore, this patent mainly studies the sampling point layout strategy. [0003] Research has shown a strong correlation between sampling strategies and the ability to detect large deviations [1]. That is, in addition to the inspection pattern, the sampling strategy also affects the accuracy of t...

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Application Information

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IPC IPC(8): G05B19/401
Inventor 何改云桑一村庞凯瑞孙静静刘晨辉
Owner TIANJIN UNIV