Pneumatic-actuated valves play an important role in many applications, including cryogenic propellant loading for space operations. Model-based prognostics emphasizes the importance of a model that describes the nominal and faulty behavior of a system, and how faulty behavior progresses in time, causing the end of useful life of the system. The prognostics demonstration rig (PDR) is an apparatus that will be used to showcase how remaining life prediction would work in the context of cryogenic refueling operations.

We describe the construction of a testbed consisting of two different types of pneumatic valves that allows the injection of faulty behavior and controllable fault progression. One valve type opens discretely, and is controlled through a solenoid valve; the other valve type opens continuously, and is controlled through a current-pressure transducer. Controllable leaks of pneumatic gas in the testbed are introduced through proportional valves, allowing the testing and validation of prognostics algorithms for pneumatic valves.

The cryo test-bed will allow the integration of the demonstration rig through ports in the pneumatics. Sensor data collected from the different transducer will be made available for the prognostic algorithms. A system-level prognostics approach is used that takes into account the interaction of the controlling solenoid valve and current-pressure transducer in the behavior of the pneumatic valves. Testbed experiments demonstrate and validate the approach.