"NI tools made it easy for us to create a test program that gave us real-time test results that were easy to analyze." – Anuchit Narkglom, Sensornic.CO.,LTD

The Challenge:
Integrating resonant vibration and image processing nondestructive testing in a single measurement cabinet by combining fast Fourier transform (FFT) testing and machine vision.

The Solution:
Using NI hardware and NI LabVIEW software for nondestructive testing with reliability measurements.

Application Software Requirement

Our application had the following software requirements:

• FFT measuring functions
• FAIL stop, test jump, test hold functions
• Test data and test results output functions
• FAIL map display function
• Database back up
• Image processing function
• Continuous FAIL stop function
• Password protection function
• Test data auto backup function
• Switch test (A/B) data function
• Network connectivity

We developed an automated test system to improve test process quality and productivity. NI tools made it easy for us to create a test program that gave us real-time test results that were easy to analyze. We used the NI Developer Suite with the Sound and Vibration Option to create the FFT application that detects uncompleted assembly parts. For image processing, we used the Image Acquisition and Machine Vision Option for NI Developer Suite to visually inspect for connector misalignment.

We used NI PXI hardware including the 8-slot NI PXI-1042 chassis with the NI PXI-4472B dynamic signal acquisition module and the NI PXIe-8234 dual gigabit Ethernet interface.

We also used an NI vision module and the PXI-6515 digital I/O interface to control the automation equipment.

FFT Method

We use the knocking vibration from a hammer to collect the amplitude peak and compare it with vibrations from each sensor: A, B, C, and D. If the results are within specified limits, the FFT judges it as 'ok.’

Error of Vibration Knocking

After knocking, FFT sets T1 at the peak amplitude of hammering. T1 refers to T1-T2 in the vibration sensors graph. Then FFT collects the highest amplitude value to compare with the standard graph.

Machine Vision Method

We used the following machine vision method:

1. Create a green rectangle around an inspection area of main image
2. Input score in 'Set Score’ and then click 'Add Template’
3. The image shows at 'Template-Sticker' and 'Template Name' has a template that we add
4. Click 'Check Template’ to inspection, score shows in 'Get Score’
5. If you have many templates to inspect, you can click the 'Check All' button to check all templates
6. To delete templates, select the template name and then click the 'Delete Template' button

Database Backup

This system can back up test data to external hard drive and find history data more easily. We use an SQL link with LabVIEW.

Conclusion

We used NI PXI hardware and powerful LabVIEW software to create a high-performance test system that tests two functions at the same time using resonant vibration and image processing nondestructive testing. We use the system to continuously test and achieve cycle time and it is easy to change the product model under test.

The automatic setup test equipment parameter improved the product quality. We can analyze the results in real time and have a data base to verify test data such as reject products. All test data history is backed up by external hard drive and is kept for 10 years following an automotive customer requirement.