ASME B89.4.10 pdf download

ASME B89.4.10 pdf download.Methods for Performance Evaluation of Coordinate Measuring System Software.
A critical issue in industrial coordinate metrology is the measurement of a work piece to assure compliance with its dimensional requirements. When using a computerized coordinate measuring system (CMS). the usual practice is to correlate computer-calculated outputs with the dimensional requirements of the workpiece. This correlation is performed by various computer routines that process dimensional coordinate data sets consisting of measurement samples of the obêect being evaluated,
The purpose of this Standard is to provide guidelines for evaluating the quality of solutions generated by CMS software and to define minimal documentation requirements for software providers. Additionally, this Standard gives default definitions for collections of data sets that span a variety of real•world measuring scenarios. These data sets are dependent on the fitting algorithm being tested. This Standard Is concerned with testing the behavior of algorithm Implementation, not the testing of algonthms themselves. Thus, the software is treated as a black box; only the input and output are observed and evaluated. It is nor the Intent of this Standard to endorse or rate any computational method or system.
Software performance evaluation Is useful because IL
(a) allows objective validation of software
(b) reduces the possibiLity of error in software application
(c) defines a method of comparing CMS software
This Standard covers the following areas: input data, feature construction, soitware documentation, performance
characterization, and test methodologies.
1.1 AssumptIons (21
The assumptions inherent in this Standard are as follows:
(a) Measurement uncertainty in coordinate samples is not addressed.
(b) Methods to input predetermined samples to the computational system are available.
(c) Personnel have adequate experience and training to implement the evaluation and understand the implications of the results.
1.2 AppLicatIon
This Standard Is one component required for the evaluation of CMSs. Other relevant documents can he found in Nunmandatory Appendix E.
1.3 References
The following is a list of standards referenced in this Standard. Unless otherwise noted, the most recent edition shall apply.
ASMF Y14.5, Dimensioning and Tolerancing
ASME Y14,5.1, Mathematical Definition of Dimensioning and Tolerancing Principles
Publisher: The American Society of Mechanical Engineers (ASME), Two Park Avenue. New York, NY 10016-5990 (wwW.asme.org)
See Nonmandatory Appendix E for additional, informative references.
2 DEFINITIONS
algorithm: a well-defined procedure for solving a particular problem. e.g.. sorting algorithms.
8-1 GENERAL INFORMATION
This Appendix presents an example of acceptable documentation. The example is not necessarily acceptable mrasure• ment practice.
DISCLAIMER: The sole purpose of thIs example Is to demonstrate adequate documentation practice and should not be construed as explicitly or impikitly endorsing or requiring any single method of calculation. Input, output, illustration. etc. A hypothetical brand CMM, XCMM with a native language XMML l used In the following example.
In this example, 15 poInts have been measured on a surface and assigned toa set called PLANE1 and are tobe evaluated against a tolerance of 0.010 mm.
8-2 PROCEDURE NAME
The procedure name Is flatness.
8-3 BRIEF DESCRIPTION
This procedure calculates the flatness of a plane.
8-4 STANDARDS COMPLIANCE
Calculations of flatness comply with the Following standards: Standard XXX and Standard YYY.
8-5 EXPLANATION OF PROCEDURE
To calculate the flatness ota geometric plane, using data points that are a sample of the surface, which approximates the plane, and then evaluate it against a tolerance value.
8-5.1 Intent
A least-squares plane Is calculated from the measured points assigned to the set PLAN El. The distances between the least-squares plane and the two extreme points on each side of this plane is calculated, e.g.. 0.0011 on one side and 0.0022 on the other. These distances are added with the result being the calculated flatness value, e.g.. 0.0033. This calculated difference is compared to the tolerance (0.0 10 — 0.0033).
8-5.2 Underlying PrincIples
To find an ideal plane, the sum of the squares of the normal distances from each point to the plane is a minimum. Once this plane Is determined, the farthest point on each side of the plane is resolved. The distance between these two points Is calculated, normal to the plane, and identified as the flatness.
8-5.3 ILLustrated ExampLe
See Figure 8-5.3-1.
8-5.4 LimItations and Precautions
Flatness procedure can be accessed in the following ways:
(a) pressing the = symbol on the keypad and typing In the name PLANE1. AL the prompt, enter the tolerance value of 0.010.