In the effort to lighten engine control systems, future engine control functions may be distributed throughout a network to different smart nodes, which may contain a sensor, an actuator, and signal conditioning. In addition to weight savings from lightening the central engine controller, significant weight savings might be achieved by decreasing the number of wires and the length of wiring in engine instrument/control wiring harnesses. Wireless smart nodes are one approach that could be developed, but the nodes would have to be constructed with currently available high-temperature electronics, which are limited in available components. In addition to requiring complex components, wireless nodes must be provided with power through at least two conductors (power and ground).
Although energy harvesting may enable complete wireless sensing and actuation, state-of-the-art energy harvesting will not support the power budget required. One method that will decrease wiring weight and complexity, while taking advantage of the necessary power lines, is communication over the power lines. One type of distributed engine control involves smart nodes that can condition signals from the sensors and generate actuating signals for the actuators, effectively closing the loop internally while still communicating with a central controller. On-node sensor signal conditioning and actuation results in less bus bandwidth for the node, and less processing for the central controller. Many obstacles must be overcome to reach the goal of distributed engine control, including the insufficient availability of high-temperature electronic components and the complex parameters of the available components.
The flight electronics laboratory team in the NASA Glenn Research Center’s Optical Instrumentation and NDE Branch is researching different approaches for enabling high-temperature smart nodes. One approach is to use commercially available high-temperature components and a capacitive coupling communication technique to transmit data on the power bus. This technique is being developed for a demonstration in Glenn’s distributed engine control testbed.
The top figure demonstrates serial data being passed over a 10-V power line via a capacitive coupling technique and commercially available industrial temperature components. The bottom figure shows an analogous demonstration of the same technique using high-temperature electronic components, rated to 225 °C, or to 260 °C for short periods. This demonstration was done at room temperature using high-temperature semiconductors but with military temperature-range resistors and capacitors. The data are serial at1.2 kbaud, transmitted with an 18.5-kHz carrier. This technique is scalable to higher baud rates representative of A, B, C, and D band communications. Because this is a bit-recessive technique, it could be used to implement a Controller Area Network (CAN) bus-based communication protocol.
Industrial temperature circuit (at room temperature).
High-temperature circuit (at room temperature).
The major advantage of this technique over commercially available power line transceiver systems is that it can be realized immediately for high-temperature and radiation-rich environments. Plans call for this communication technique to continue to be developed and tested at high temperatures and to be incorporated into an engine simulator testbed.
Find out more about the research of Glenn’s Optical Instrumentation & NDE Branch: http://www.grc.nasa.gov/WWW/OptInstr/
Glenn contacts:
Michael J. Krasowski, 216-433-3729, Michael.J.Krasowski@nasa.gov
Norman F. Prokop, 216-433-6718, Norman.F.Prokop@nasa.gov
Larry C. Greer, 216-433-8770, Lawrence.C.Greer@nasa.gov
Authors:
Michael J. Krasowski, Norman F. Prokop, Lawrence C. Greer, and Danny C. Spina
Headquarters program office:
Aeronautics Research Mission Directorate
Programs/projects:
Fundamental Aeronautics Subsonic Fixed Wing
Last updated: October 16, 2007
Responsible NASA Official:
Gynelle.C.Steele@nasa.gov
216-433-8258
Point of contact for NASA Glenn's Research & Technology reports:
Cynthia.L.Dreibelbis@nasa.gov
216-433-2912
SGT, Inc.
Web page curator:
Nancy.L.Obryan@nasa.gov
216-433-5793
Wyle Information Systems, LLC
