The Diagnostics and Prognostics (DnP) group maintains a laboratory to support the research of the prognostic techniques. Specifically, we are using the lab to understand some of the basic faults of the components to better model the damage they are incurring. We are also using the lab to age components and to generate data sets to test and ultimately support validation of the prognostic techniques.
The equipment directly available to the Diagnostics and Prognostics (DnP) group encompasses a 0.7m3 environmental chamber that allows the control of temperature (-60oC to 170oC), altitude (sea level to 30,000m), and humidity. Also available is a shaker that can accommodate small test articles (<1 kg) such as small wiring harnesses and computer boards. Several programmable loads, waveform generators, power supplies, oscilloscopes, data acquisition cards allow the automated aging of components and automated data collection. Electrochemical impedance spectroscopy equipment allows the probing of battery cells. A scanning electron microscope will be used in conjunction with sectioning equipment to perform forensic analysis of semiconductor devices.
Part of the Electronics Lab
Aging platforms have been designed or are underway to age batteries, MOSFETs and actuators.
Insightful View of the Environmental Chamber
Several demo stations allow the demonstration of the technology developed. These include:
Electro-Mechanical Actuator Test Stand
Electro-mechanical actuator (EMA) test stand has been designed and built in collaboration with Impact Technologies. It will be used in experiments studying diagnostic and prognostic methods for ball-screw jams, spalling, abnormal wear, backlash, as well as electronics and power failures. Dynamic load for the test actuator is provided by a powerful Moog 886 load EMA that can produce up to 5 metric tons of opposing force. The control system of the stand will allow custom load profiles and long-term, endurance testing. Instrumentation includes a load cell, accelerometers, high-precision position sensors, and temperature sensors. The data acquisition system allows recording of data samples with frequency of up to 64 kHz. The flexible design of the stand accommodates test actuators of various sizes and configurations.
The test stand has become operational in September 2008.
This test bed is meant to provide a realistic development environment for future experiments in electro-mechanical actuator prognostics on manned and unmanned aircraft (such as NASA DFRC F-18 and NASA LaRC AirStar UAVs). It has been constructed from a wing section of a surplus Boeing 727 airliner. The section contains segments of the aileron, the aileron trim tab, and the leading edge flap. The original hydraulic aileron actuator has been removed and replaced with a Moog 883-023 electro-mechanical actuator and T200 controller. The leading edge flap and aileron trim segments will be utilized for future experiments.
The next steps in development of this test bed include:
Boeing 727 Aileron Wing Section Test Bed
The Advanced Diagnostic and Prognostic Testbed (ADAPT) is an electrical power system testbed developed at the NASA Ames Research Center. ADAPT provides: (i) a standard testbed for evaluating diagnostic algorithms and software; (ii) a capability for controlled insertion of faults, giving repeatable failure scenarios; and (iii) a mechanism for maturing and transitioning diagnostic technologies onto manned and unmanned vehicles.
The EPS functions of ADAPT are as follows: For power generation, ADAPT currently uses utility power. For power storage, ADAPT contains 2 sets of 24 VDC 100 Amp-hr sealed lead acid batteries and 1 24 VDC 50 Amp-hr battery. Each battery set comprises two 12 VDC batteries connected in series. Power distribution is aided by electromechanical relays and two load banks with six AC and two DC outputs; there are also several circuit breakers. At the present time, ADAPT loads include pumps, fans, and light bulbs. There are sensors of several types, specifically for measuring voltage, current, relay position, temperature, light, and liquid flow. Control and monitoring of ADAPT takes place through programmable automation controllers from National Instruments. With the sensors included, ADAPT contains a few hundred components and is representative of EPSs used in aerospace.
Goebel, Kai, Ph.D.
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