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 Student Spotlight continued
at the university for initial prototyping. For this first-generation, he enlisted the help of his son to create a simple integrated circuit to control the valve operation and timing cycling between inspiration and expiration phases (Figure 1).
With its promising results, the first-generation device gave the team confidence to continue design. Though effective for testing the initial concept, the integrated circuit was cumbersome to adjust, and the engineers needed to be able to modify the inspiration to expiration (I/E) ratio. To speed development
efforts and enable rapid testing and adjustment, the developers introduced a programmable Arduino prototype board to replace the integrated circuit.
This second-generation configuration gave the team the tools it needed to greatly refine the mechanical,
Figure 1: For early-generation CPAP-based ventilator designs, the team prototyped with basic and readily available parts.
Student Spotlight | Issue 44
electrical, and controls components of the system, but it still lacked the reliability necessary to function in a life-critical capacity.
At this point in development, Dr. Burch enlisted the expertise of his friend Jim Chapman, an industry controls engineer. Chapman quickly specified the use of the AutomationDirect CLICK programmable logic controller (PLC) to replace the prototype
board (Figure 2). This commercially available PLC would make it easy to program and modify the configuration, while delivering the reliability and robustness demanded by the application. This third-generation device formed the basic automation architecture for RE-INVENT.
With the further addition of an AutomationDirect C-More human-machine interface (HMI), users could better interact with the automation, so making adjust- ments to settings like the I/E ratio during testing became even simpler.
Development up to this point transpired of a mat- ter of days, literally over a weekend. Such results rep- resented a turbo-charged pace compared to the
rate at which most machines—let alone medical devices—are developed.
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Editor's Note
New Product Focus
- Expaded communications and analog I/O capabilities for the
- Control cabinet cable entry systems
- DURApulse® GS20 Series high performance AC drives
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- Enclosure Thermoelectric Coolers
Tech Thread
Improvies, Adapt, Overcome
Business Notes
Cover Story
The Best Automation HMIs Keep Things Simple
What's New
User Solutions
- Water Utility Successfully Standardizes Automation Practices
- Automating the Hendrick's Gin Grand Garnisher
Student Spotlight
CPAPs RE-INVENT ed into Ventilators Using PLCs & HMIs
Break Room
        Figure 2: The readily available and economical AutomationDirect CLICK PLC made it easy to develop the ventilator, and delivered the reliability needed for such an application.
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