LabVIEW and PXI tools verify electrical assemblies

Freightliner, a leading North American manufacturer of heavy trucks, selected NI LabVIEW software and NI PXI-based hardware to replace a VME-based proprietary system for verifying electrical assembly on its new line of heavy-duty trucks. Using NI tools, Freightliner engineers integrated electrical test, machine vision and physical measurements into a system that not only ensures high-quality vehicles but also instructs operators on the correct assembly process.

John Rokus, Manufacturing Manager of Test and Technology at Freightliner LLC, says: "We set out to design a high-performance test system that would give us the flexibility of a completely off-the-shelf solution and provide both the open architecture and power for expanding the application in the future. This system delivers on both requirements and the successful development is reflective of the valuable relationships Freightliner enjoys with both external and internal resources."

Freightliner chose Wineman Technology Inc, a specialist machine designer and a leading National Instruments Alliance Partner, to create the test systems to meet its requirements. Wineman Technology has a strong history of meeting customer needs using PXI-based systems. The platform's ability to deliver on flexibility and performance, as well as be more cost-effective than the previous system, made it a natural choice for this application. Along with electrical and physical measurements, the new system includes a machine vision system for inspecting fuse box assembly. This features industry-standard cameras that were built into a custom fixture and coupled with software written in LabVIEW.

Integration with plant information system

The software communicates with the plant information system to acquire a build order specific to each truck. The software then graphically prompts the operator to place the fuses and relays in their proper positions in the fuse box or switch activation module (SAM). Once finished, the operator prompts the system to take a digital picture of the populated assembly and compares it with the computer-generated image of the build order to produce a pass or fail rating. In the event of a failure, the software locks the part in place and notifies the operator which fuse or relay has been placed incorrectly, and graphically identifies the part and its correct placement.

Darryn La Zar, Vice President of Sales and Marketing at Wineman Technology, explains: "Using machine vision to verify the assembly of the fuse box goes beyond the industry standard of validating serial fuse continuity. For instance, this can detect if a 30A fuse is in a 5A slot, which was not possible before."

Once the tests are completed, a Cumulative Offline Report provides an interactive resource for technicians to view results of all previous test systems for any given truck. A 'to do' list is generated in the event that any test failures could not be repaired in station. In addition, if there are any special truck options that require additional setup or validation, this system compiles those requirements so that a technician can be sure to address them prior to releasing the vehicle.

The new test systems Wineman Technology is building for the plant include all-new cockpit and cab testers that are capable of reading multiple signal types across 512 discrete wires that users can connect directly to the assemblies. By integrating LabVIEW software and PXI hardware with proprietary PROVEtech software from Mercedes-Benz Technology, the three-way partnership between Freightliner, Wineman and Mercedes-Benz produced a system capable of guiding the operator through each step of the process required to validate all electrical signals that could have been assembled incorrectly or damaged during the assembly process.

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