System and method for characterizing surfaces using size data

Patent metadata

Field	Value
Publication number	US-2016202036-A1
Application number	US-201414903212-A
Country	US
Kind code	A1
Filing date	Jul 7, 2014
Priority date	Jul 9, 2013
Publication date	Jul 14, 2016
Grant date	—

Abstract

A system and method for characterizing surfaces includes using a measuring device to take size measurements of a manufactured product. The raw measurement data is transformed from a time-based domain to a frequency-based domain using a mathematical algorithm. The transformed size measurement data is then compared to predetermined limits within comparable frequency bands to characterize the surface of the manufactured product.

First claim

What is claimed is:

1 . A method for characterizing surfaces comprising:
taking size measurements of a feature of a manufactured product over time; using the size measurements to yield size measurement data in a time-based domain; transforming the time-based domain size measurement data to frequency-based domain size measurement data; and comparing at least some of the frequency-based domain size measurement data to a predetermined limit to characterize the surface of the feature.

2 . The method of claim 1 , further comprising comparing at least some of the size measurement data to a limit.

3 . The method of claim 1 , wherein comparing at least some of the frequency-based domain size measurement data to a predetermined limit is performed using only the frequency-based domain size measurement data within a predetermined wavelength band.

4 . The method of claim 3 , wherein comparing at least some of the frequency-based domain size measurement data to a predetermined limit is performed using only the frequency-based domain size measurement data of maximum amplitude within the predetermined wavelength band.

5 . The method of claim 3 , wherein comparing at least some of the frequency-based domain size measurement data to a predetermined limit is performed using a sum of all of the frequency-based domain size measurement data within the predetermined wavelength band.

6 . The method of claim 1 , wherein the predetermined limit is defined by a process including:
(a) taking size measurements of a feature having an acceptable surface finish of a manufactured product over time to yield a data set of size measurement data in a time-based domain; (b) removing from the data set size measurement data corresponding to wavelengths over a predetermined length; (c) calculating a peak-to-valley value for the size measurement data in the data set; (d) transforming the time-based domain size measurement data in the data set to frequency-based domain size measurement data to yield a frequency-based domain data set; repeating (a)-(d) for features of additional manufactured products to yield a plurality of frequency-based domain data sets; and defining the predetermined limit based on the frequency-based domain data sets.

7 . The method of claim 6 , wherein defining the predetermined limit based on the frequency-based domain data sets includes:
determining the size measurement of maximum amplitude within each of the frequency-based domain data sets to yield a maximum amplitude data set; calculating mean and standard deviation for the maximum amplitude data set; and defining the predetermined limit as a predetermined number of the standard deviations away from the mean.

8 . The method of claim 6 , wherein defining the predetermined limit based on the frequency-based domain data sets includes:
determining a sum of the size measurements for each of the frequency-based domain data sets to yield a sum-of-sizes data set; calculating mean and standard deviation for the sum-of-sizes data set; and defining the predetermined limit as a predetermined number of the standard deviations away from the mean.

9 . A method for characterizing surfaces comprising:
measuring a diameter of a feature of a manufactured product over time; using the diameter measurements to yield a first data set consisting of time-based domain diameter measurement data; transforming the time-based domain diameter measurement data to frequency-based domain diameter measurement data to yield a second data set consisting of frequency-based domain diameter measurement data; and comparing a subset of data from the second data set to a predetermined limit to characterize the surface of the feature.

10 . The method of claim 9 , wherein the subset of data from the second data set includes only the frequency-based domain diameter measurement data within a predetermined wavelength band.

11 . The method of claim 9 , wherein the subset of data from the second data set includes only the frequency-based domain diameter measurement data of maximum amplitude within a predetermined wavelength band.

12 . The method of claim 9 , wherein the subset of data from the second data set includes only a sum of all the frequency-based domain diameter measurement data within a predetermined wavelength band.

13 . The method of claim 9 , further comprising performing a learning mode process on features of respective manufactured products having an acceptable surface finish to define the predetermined limit.

14 . The method of claim 13 , wherein the learning mode process includes:
(a) taking diameter measurements of a feature having an acceptable surface finish of a manufactured product over time to yield a data set of diameter measurement data in a time-based domain; (b) removing from the data set diameter measurement data corresponding to wavelengths over a predetermined length; (c) calculating a peak-to-valley value for the diameter measurement data in the data set; (d) transforming the time-based domain diameter measurement data in the data set to frequency-based domain diameter measurement data to yield a frequency-based domain data set repeating (a)-(d) for features of additional manufactured products to yield a plurality of frequency-based domain data sets ; and defining the predetermined limit based on the frequency-based domain data sets.

15 . The method of claim 14 , wherein defining the predetermined limit based on the frequency-based domain data sets includes:
determining the diameter measurement data of maximum amplitude within each of the frequency-based domain data sets to yield a maximum amplitude data set; calculating mean and standard deviation for the maximum amplitude data set; and defining the predetermined limit as a predetermined number of the standard deviations away from the mean.

16 . The method of claim 14 , wherein defining the predetermined limit based on the frequency-based domain data sets includes:
determining a sum of the diameter measurement data for each of the frequency-based domain data sets to yield a sum-of-diameter measurement data set; calculating mean and standard deviation for the sum-of-diameter measurement data set; and defining the predetermined limit as a predetermined number of the standard deviations away from the mean.

17 . A system for characterizing surfaces, comprising:
a control system having at least one controller and configured to receive information related to size measurements of a feature of a manufactured product taken over time to yield size measurement data in a time-based domain, transform the time-based domain size measurement data to frequency-based domain size measurement data, and compare at least some of the frequency-based domain size measurement data to a predetermined limit to characterize the surface of the feature.

18 . The system of claim 17 , wherein the control system is further configured to use only the frequency-based domain size measurement data within a predetermined wavelength band to compare to the predetermined limit.

19 . The system of claim 18 , wherein the control system is further configured to use only the frequency-based domain size measurement data of maximum amplitude within the predetermined wavelength band to compare to the predetermined limit.

20 . The system of claim 18 , wherein the control system is further configured to use only a sum of all the frequency-based domain size measurement data within the predetermined wavelength band t

Assignees

• Ford Global Tech Llc

Inventors

• Jalluri Chandra Sekhar
• Hamidieh Youssef A

Classifications

• G01B7/125

  of objects while moving · CPC title

• G01B5/08

  for measuring diameters {(G01B5/0035 takes precedence; measuring radius of curvature G01B5/213)} · CPC title

• G01B7/12 Primary

  for measuring diameters · CPC title

• G01B5/003 Primary

  Measuring of motor parts · CPC title