Online Cable Tester and Rerouter
- Monday, 01 October 2012
This technology enables proactive detection of impending cable failures, allowing for function rerouting.
Hardware and algorithms have been developed to transfer electrical power and data connectivity safely, efficiently, and automatically from an identified damaged/defective wire in a cable to an alternate wire path. The combination of online cable testing capabilities, along with intelligent signal rerouting algorithms, allows the user to overcome the inherent difficulty of maintaining system integrity and configuration control, while autonomously rerouting signals and functions without introducing new failure modes. The incorporation of this capability will increase the reliability of systems by ensuring system availability during operations.The operation of the innovation is based on the injection of a low-level and short-duration signal into a wire under test. The cable router master unit consists of a pulse generator, a multiplexer, a switch matrix, and a detector circuit. The pulse generator provides a step pulse that is applied to the multiplexer. The multiplexer, in turn, routes the test pulse to one of many wires. The signal then propagates through the selected wire until it reaches the cable route slave circuit. The slave circuit monitors the wire, and once it receives the signal, it routes it back to the master unit through a communication wire. The detector circuit in the master unit then determines the presence of the signal to indicate that a good connection is in place. The absence of the test pulse becomes an indication of a faulty connection. A plurality of communication wires is used, so that the individual state of health is not a determining factor for the analysis of the health of the wire(s) under test.
The master unit sequentially scans all the wires selected as “active” or “spares.” The current implementation of the online rerouter system can monitor up to eight wires. However, the circuit can be expanded to monitor a larger number of wires. The wires can be independently assigned to be “active” or to be “spares.” Once an active wire has been labeled as failed, the master and the slave units communicate with each other, and immediately route the signals that were flowing through the failed wire to one of the spare wires. This allows for the system to maintain integrity with a disruption shorter than one second in the current implementation.
The small amplitude of the test pulse injected into the wires requires multiple successive measurements to assess the integrity of the wire. The test pulse level has to be maintained at a low level in order not to interfere with signals being carried in the wire under test. This allows for discrimination between a large, non-correlated signal and a small, synchronous test pulse without interfering with the operation of the wire.
This work was done by Mark Lewis of Kennedy Space Center and Pedro Medelius of ASRC Aerospace Corporation. For more information, contact the Kennedy Space Center Innovative Partnerships Office at 321-867-5033. KSC-13440