The client required very detailed appliance testing in order to compare the performance of their products to their competitors’ and to make strategic decisions for new models. Their offerings included a broad range of appliances, and each required dozens of different tests in order to span each product’s entire range of features. Some tests required continuous data collection that could be weeks long. The client was familiar with DMC’s deep knowledge of electrical and mechanical engineering, as well as our expertise in custom software and hardware design. DMC worked closely with the client during a dedicated specification phase to ensure that all of their needs and requests for the system were accurately captured, including such details as transducer types, software interface preferences, future expandability, and user experience.
During the build phase, DMC worked with a trusted industry partner to complete design, electrical and mechanical drawings, construction, and testing. Together, we built and tested each test-stand completely so that the client was free from the technical responsibilities of wiring, plumbing, power, and safety issues. The result was a set of fully completed turnkey test-stands that could be shipped directly to the client’s new laboratory.
The goal during software design was to present the user with a simple user interface that could initiate common tests very quickly, but also permitted completely flexible and customizable data-acquisition when desired. For example, the user can start the software and initiate a commonly-run power-consumption test within seconds. Or, the user can choose individual data-acquisition devices and run a fully custom test without requiring any other technical details about the transducers being used.
While most appliances are only active for brief periods, refrigerators demand much more rigorous testing. The refrigerator test-stand therefore employed a rugged data-acquisition solution that could reliably acquire data, in the presence of the accompanying PC or not, for over a week. This was achieved with a real-time computer, NI’s CompactRIO 9114, which collected data and sent it to the test-stand PC. To promote usability and familiarity, the PC software exposed the same user interface for refrigerators as for other appliances. If the PC crashed or became disconnected, the cRIO would cache data locally until the PC became available. This recovery procedure prevents an expensive loss of time due to an unexpected PC issue during a very long test.
The entire project was built with extensibility in mind. Adding more tests only requires software changes if a specific calculation is required for a test. In general, new tests can be added by simply specifying the desired transducers and user input data. The test-stands initially supported several transducer types to make many different measurements: voltage, current, power, humidity, temperature, water flow & pressure, gas flow & pressure, and more. More transducer types can be added easily using NI’s Measurement and Automation Explorer.
After each test, all data is saved to an on-site Windows server. The test data is summarized and logged to the server’s SQL database. A secondary application written by DMC allows users to search the database for tests matching certain criteria. It can then load the data for display and analysis. Separate software packages for data acquisition and data analysis, combined with a central server, permits the user to conduct analyses outside the lab or even outside the facility.
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