Comparação entre algoritmos de mínimos quadrados e de zona mínima para desvios de circularidade

AUTOR(ES)
DATA DE PUBLICAÇÃO

1996

RESUMO

The precisely assessment of out-of-roundness is an important issue in metrology. There are always errors associated with these measurements, caused by different sources. The computer aided measuring machines have an additional source of error, the algorithm itself. This subject was only recently in flux. The main objective in this work is to determine the behavior of minimum zone center (MZC), conceptually the most correct, in comparison with least square center (ESC), used in practice. In order to analyze the differences between the algorithms answers, computer simulations were used. Both algorithms were developed in C language, and a third program generated thousands of sets similar to that obtained through CMMs. The algorithm of Voronoi diagrams, MZC type, was developed. The choice s reasons were the optimization assurance, low complexity and implementation facility. The out-of- roundness values, numbers of points of the set and the radius of the workpiece were varied to simulate industry environment. The results showed that the Voronoi algorithm gets a pair of concentric circles with separation equal or less then the LSC one. The difference between the results could be about 30% or greater, depending on the points distribution. The behavior of the maximum errors between results depends on the number of points and the value interval of out-of-roundness. for some CMMs used in industry, the uncertainty of the machine is greater then the maximum error caused by algorithm s choice. This is true for various number of points and out-of-roundness. In these cases the LSC is allowed. Also when only LSC is available, the maximum expected error could be minimized increasing the number of points. For dedicated machines and CMMs more accurate, the algorithm is an important source of error. The MZC algorithms are always necessary in these cases. through the results one could presume that the development of other minimum zone algorithms, such as cilindricity and sphericity, will be very important for metrology in future.

ASSUNTO(S)

maquinas de medição por coordenada tolerancia (engenharia) algoritmos normalização medição minimos quadrados

ACESSO AO ARTIGO

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