Analyze the Correlation and Perform Correlation Compensation

When deploying the Mech-Metrics project, you need to analyze the correlation between the measurement data from the Mech-Mind inline measurement system and the CMM. Based on this analysis, compensation values are calculated to correct deviations in the Mech-Mind inline measurement system, aligning its measurements more closely with the CMM to improve its accuracy.

Correlation refers to the degree of consistency between the measurement results of two different measurement devices when measuring the same dimension of the same part.
Error compensation is a technique or method used to correct measurement or operational errors caused by uncertainties, inaccuracies, or deviations by adjusting or calibrating the output of a system or device. The purpose of error compensation is to improve the accuracy of the system or device, ensuring its output is closer to the true or target value.
Correlation analysis and compensation refer to analyzing the relationship between the measurement results of two different measuring devices, followed by compensating the results of one device to improve the reliability of the device.

Select Measurement Records

In this step, you can select the desired measurement records for subsequent data association.

Measurement records refer to the measurement data stored in the historical data of the software.

In the top ribbon of the software Configuration interface, select Analysis and Compensation Correlation Compensation.
On the Select measurement records tab of the Correlation Analysis and Compensation dialog box, select the part features to be included in the analysis and compensation.
Select the time range based on actual needs and click Check selected data.
On the Tables tab of the pop-up Historical Data dialog box, select the check box next to Quick selection. Then, all measurement records in the tab will be selected.
Check the Result column of each measurement record. NG indicates that the measurement record is unqualified. Invalid indicates that the measurement record is invalid. Deselect all measurement records marked as NG and Invalid, click Apply, and then click Next.

Import third-party CMM measurement reports

This step imports third-party CMM measurement reports for calculating correlation compensation values.

On the Import third-party CMM measurement reports tab of the Correlation Analysis and Compensation dialog box, click Obtain report template to download the report template and then modify the format of the your CMM measurement report to based on the template.
Click Import, select one or more report files of the same format, and then click Open to import the files.
If the import fails, troubleshoot the issue based on the displayed error message.
After the files are imported, you can click a file in the Select CMM reports section and then view the file content in the View file content section. Click Next.

Associate measurement records with CMM reports

This step associates the measurement records in the software with the imported third-party reports.

On the Associate measurement records with CMM reports tab of the Correlation Analysis and Compensation dialog box, click Associate.

To improve the accuracy of correlation analysis and compensation, you can associate measurement records with parts and third-party measurement reports with the parts. In this case, the compensation values are derived from the average of the data in the measurement records and the average of the data in the third-party measurement reports.
You can also choose not to associate them and directly click Next. In this case, the compensation values are derived from the average of all data.

In the Associate data section, associate measurement records with parts and measurement reports with the parts. To perform the association, double-click the Part alias column of a task ID or report to enter drop-down mode. In drop-down mode, select an alias for each task ID and report.

How to create an alias?

To create an alias, double-click in the Part alias column of a task ID or report to enter drop-down mode. In drop-down mode, select New.
In the New Part Alias dialog box, enter a name and click OK.

After you select a corresponding alias for each task ID and report, click Next.
If the number of part aliases associated with the reports does not match the number of part aliases associated with the task IDs, the Next button cannot be clicked.

Analyze correlation and calculate compensation

This step analyzes correlation and calculate the correlation compensation values for each measurement item.

On the Analyze correlation and calculate compensation tab of the Correlation Analysis and Compensation dialog box, click Export MSA to export the MSA report.

Measurement Systems Analysis, short for MSA, is a set of experiments and analyses used to evaluate the capability, performance, and measurement uncertainty of a measurement system. The MSA report is a report provided by Mech-Metrics to evaluate the reliability of the inline measurement system.

If you are not satisfied with the data in the MSA report, you can choose not to perform correlation compensation. At this point, no further action is required. If you are satisfied with the data in the report, you can proceed with the following steps.

On the Analyze correlation and calculate compensation tab of the Correlation Analysis and Compensation dialog box, click Calculate.
The calculation result will be displayed in the View result section. You can check the result. If you are satisfied with the result, click Apply. After you click Apply, the compensation values will take effect in the subsequent measurements.

In addition to correlation compensation, Mech-Metrics allows you to perform manual compensation. The steps for manual compensation are as follows:

In the Resource Tree section on the left side of the current part, click on a measurement item (a feature, geometric measurement, or GD&T measurement). Then, in the parameter panel area of the measurement item on the right side, click to the left of Compensation to expand the Compensation section.
In the Compensation section, enter the compensation value. For example, if the deviation value of a specific measurement sub-item of this measurement item is -5 (this deviation value can be found in the annotation of the measurement item), you can enter 5 as the compensation value. If an annotation has not been created for the measurement item, create one for the measurement item. The creation steps have been introduced earlier and will not be repeated here. For more information, see Create an Annotation for the Feature.
After you enter the compensation value, check the current deviation in the annotation. If the current deviation value is displayed as 0, it indicates that the manual compensation was successful.