Medical Device Test System
How S5 Solutions designed an ATE with modular hardware and software to increase dependability
The client had a line of medical equipment with a strong sales history. With their market going strong and a new model about to be introduced, they were looking for a path to update their production test system.
A medical device manufacturer client had an old test system. Wear and age had taken a toll. It required increased maintenance and attention to keep it running dependably.
The software was suffering from a similar problem. Although software doesn't wear out like hardware does, things change around it. It saved reports in an old format that did not comply with the new company standard. It was also still running on Windows XP, which IT would no longer allow to connect to the network, making even getting the test reports a hassle.
The system had served it's purpose for many years. It was in need of an update.
S5 engineers worked with the client's team to design the new solution. The product engineers who designed the UUT helped us understand the nuances of their design. The UUT is a device which itself acts as a calibration standard, so there were very tight requirements for accuracy.
Each UUT require complex calibration due to the nature of the device. The tight limits for calibration meant very controlled signal pathways for switching loads and measurement channels for the ATE.
One of the most challenging aspects of the design was maintaining low impedance paths for the test measurements. One of the UUTs functions is to be able to detect very small current leaks. Testing that functionality involved switching very small resistive loads in a way that minimized any effects of our switching circuitry. Other functions of the UUT require testing under high current and high voltage conditions. So the system needed to be able to handle all of those extremes.
We divided the system by functional test type and linked them via a series of busses each purposes. Since the switching requirements were so tight, we created custom switching boards rather than using a COTS switching matrix. This allowed us to mix and match the unique combination of signals the UUT requires. Each switching board has relays appropriate for the signals it uses (e.g. low impedance, high current, high voltage, etc.). These boards create a modular measurement system, each with specialized abilities.
The resulting design is reliable and easy to maintain. The flat panel layout of the modular boards allows for easy diagnostic, maintenance, and replacement.
We used the S5 Solutions ALOHA system as the framework for the software modules. Many of the modules are hardware abstractions of the measurement subsystems. They were design to be easy to change, since support for the next generation machine is next on the list. A HAL driver change will be able to support the new UUT hardware with minimal software change.
NI TestStand ties the system together, directing the ALOHA Agents, making measurements, and logging the results to the corporate reporting system. That means it can tie into the rest of the business systems for automatic creation of required FDA documentation for each of the UUTs.