Method for evaluating roundness and sphericity errors based on self-adaption iteration neighbourhood search

Abstract

The invention relates to a method for evaluating roundness and sphericity errors based on self-adaption iteration neighbourhood search, which comprises the steps of: with an initial searching region as a starting point, dividing the initial searching region through a plurality of concentric circles, spheres and a plurality of radius lines passing through the circles and the sphere center; with an intersection point of all lines as a candidate reference circle center or a sphere center for evaluating the errors, finding a reference position with minimum error through calculation; with the reference position as a position of a new searching region, determining the size of a searching neighbourhood with a corresponding error value as a radius, dividing the new searching region and evaluating all dividing points; and repeating the iteration process until an optimal solution occurs, wherein because the reference position is gradually close to the optimal position with the iteration, the searching region, i.e. the radius, is self-adaptively adjusted, because the searching initial condition, the searching region shaped, the iteration and the like are simply determined, the principle is easy to understand and calculated, and the searching interval and the step length in the searching process are self-adaptively reduced with the iteration, so that the optimal solution can be ensured to be found.

Description

technical field [0001] The invention belongs to a method for evaluating errors of coordinate measuring machine (CMM) data, in particular to a method for evaluating roundness and sphericity errors based on self-adaptive iterative neighborhood search. Background technique [0002] Shape error is an important content in the quality assessment of geometric products, and has always been widely concerned. Roundness is a basic tolerance item, which is defined as "the minimum distance between two concentric circles containing all measurement points", which is the roundness error under the minimum condition, while sphericity is not clearly defined in the standard. It is very important in practice, such as for high-precision bearing balls, so it is essential to carry out research on its theory and methods. The evaluation methods for these two items mainly include data processing algorithms for proprietary instruments, such as roundness meters, the so-called evaluation methods; there ...

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Problems solved by technology

However, the disadvantage is that the principle is more complicated and requires deeper mathematical knowledge, so it is not suitable for promotion and use.

[0006] 2008 literature [1 Huang Fugui, Zheng Yujun. Roundness error evaluation method based on area search [J], Journal of Metrology, 2008, 29(2): 117-119] Aiming at the nonlinear problem of roundness error solution, an area-based The evaluation method of search, the principle of the method is simple and easy to implement, but there are still shortcomings: the fixed search step size limits the chance of obtaining the best solution, and the appropriate step size is not easy to determine; the search objective function does not satisfy the minimum area condition

Also published in 2008 [2 Lei Xianqing, Chang Weihang, Xue Yujun, Li Yan, Li Jishun. Grid search algorithm for roundness error [J], Journal of Instrumentation, 2008, 29(1): 2324-2329] also A method similar to literature [1] is proposed, called the grid search method. This literature has the idea of ​​updating the search step size, but its search starts from the least square solution is not concise enough, the shape of the search area is square, and there is an anisotropy to the reference Situations where search opportunities are unequal

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