Creating an Automated, Highly Accelerated Stress Screening Test Solution for Three Avionics PCBs in Parallel Using LabVIEW, TestStand, and NI PXI

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"The team utilised LabVIEW, TestStand, and other NI products to provide a flexible, maintainable system, fit for purpose presently and into the future."

- Steve Bale, TBG Solutions

The Challenge:
Performing more than 50,000 tests per unit under test in parallel, each having 500 test points encompassing a wide variety of signal types, whilst situated in a highly accelerated stress screening (HASS) chamber.

The Solution:
Using LabVIEW, TestStand, and NI PXI hardware to develop fully automated test equipment that utilises the TestStand batch process model, PXI instrumentation, and switching.

Author(s):
Steve Bale - TBG Solutions

Manufacturing flaws and reliability problems can cause mission-changing and even catastrophic or fatal consequences, as well as significant financial penalties, in the avionics defence industry. To mitigate this, original equipment manufacturers are required to perform HASS testing to ensure ongoing product quality and reliability by exposing latent defects in components and assemblies. HASS testing is a form of product stress test designed to improve reliability by characterising failures and using the information to improve the design or manufacturing process. Temperature and vibration cycling are commonly performed during the HASS testing process.

TBG Solutions needed to develop a solution to test three avionics remote input/output printed circuit boards (PCBs) in parallel. TBG Solutions is a National Instruments Gold Alliance Partner that specialises in providing bespoke automated production test and measurement solutions, system maintenance, customer training, and support for a diverse customer base.

The Test System

The test system performs 50,000 electrical tests, including voltage, resistance, current, capacitance, frequency, phase, and trip, on three parallel units residing in a HASS chamber. The test system generates and executes HASS profiles, and operators can exclude or include specific tests and adjust temperature and vibration levels and ramp rates. The fully-automated parallel testing involves aircraft simulation, a two-part firmware download, highly accurate capacitance measurements, and load trip testing.

The test system utilised a PXI-8106 controller and a PXI-1045 18-slot chassis with three PXI-4065 digital multimeters, a PXI-5105 scope, multifunction DAQ devices, and various switch cards for extremely accurate, flexible, and easy measurements. We used LabVIEW to create an interface driver for each instrument within the system, and used TestStand to seamlessly sequence these drivers and other components together to create flexible test sections that could then be sequenced on the fly. We took advantage of built-in TestStand parallelisation options to test the three units as a batch, starting and ending the testing together.

TBG Solutions and TBG Manufacturing designed and built the complete system using CAD and computer-aided manufacturing,  LabVIEW, and TestStand.

Figure 1. Test Equipment Rack CAD Image

Figure 1 shows a CAD image of the test system, with the PXI device hidden behind a panel accessible from the rear of the two-bay, 19 in. rack.

Figure 2. Test Equipment User Interface

In Figure 2, a custom TestStand user interface (UI) displays an overview of the tests currently being performed for each unit and a tabular view of results and their pass/fail statuses. The UI uses the TestStand API and its callbacks to display operator-required information.

Test System Benefits

The system not only tests three units in parallel, but brings the individual single-unit test time down from three hours to 45 minutes. This means a 12X increase in test throughput, significantly reducing costs for the manufacturer and, ultimately, the consumer.

Using system software tools, operators can change test sequencing and looping and HASS parameters such as vibration level, temperature level, and respective ramp rates. Operators can create a specific test profile to replicate a real-world fault on a particular component. Using system flexibility, operators can perform diagnostics, debug testing, and R&D.

Conclusion

The final system successfully performs more than 50,000 tests per UUT in parallel whilst controlling the HASS chamber.

LabVIEW and TestStand provided such a comprehensive suite of easy-to-use functionality that the developers and designers could focus on the best way to perform tests on the unit rather than building the test executive. The team utilised LabVIEW, TestStand, and other NI products to provide a flexible, maintainable system, fit for purpose presently and into the future. This technology helped develop highly cohesive and loosely coupled tests, increasing test flexibility and software module reusability.

Author Information:
Steve Bale
TBG Solutions
3A Midland Court, Barlborough
Chesterfield S43 4UL
United Kingdom
Tel: 01246 819100
steve.bale@tbg-solutions.com

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