Date: Apr 15, 2009 Author: Joe Singleton Source: MDA (
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by Joe Singleton/jsingleton@nttc.edu
Sensors developed to monitor the structural integrity of materials used in missile defense systems soon may prevent automotive fatalities by providing early warning of highway bridge collapses.
The sensors, developed by Analatom, Inc. (Sunnyvale, CA), and made of the same metal to which they are applied, enable transportation departments to assess specific environmental data such as metal structural corrosion on bridges. The sensors send data wirelessly to portable data units that use artificial intelligence (AI) to analyze the data to predict impending structural failures.
The technology was funded by MDA through a 2006 SBIR Phase II contract to develop a wireless interface between sensor networks and portable computers for materials management and monitoring.
Analatom sensors are linear polarization resistors—devices that corrode at the same rate as the structure on which they are placed. The postage-stamp-sized sensors include two micromachined electrodes connected to a battery- or solar-powered central data node that processes the sensors' output, stores data, and communicates data wirelessly. These electrodes are made of the same material as the metallic surface to be monitored, and they are fitted onto a thin polyimide film carrier that is applied to the structure. Using the same metallic stock of the object being monitored allows the sensor to note where corrosion specifically is occurring. This approach differs from competitive sensors that use pre-programmed algorithms to monitor general environmental factors. Analatom's method relies on actual changes detected in the structure of a bridge, for example brittleness and corrosion caused by atmospheric conditions or moisture—rather than relying on algorithmic guesses.
Analatom generally manufactures its sensors using a photolithography technique. The photolithographic machining allows for a variety of product shapes so the sensors can fit deep into tight structures such as bridge cables and lap joints. Once the sensor is placed on a metallic surface for monitoring, the unobtrusive device can be camouflaged with paint.
The micromachined electrode sensors and a central data node are manually attached to a monitored object, such as a bridge. The sensors collect information regarding environmental conditions and corrosion, which is then processed by the central data node, also located on the structure. An engineer inspecting a bridge would use an Analatom-manufactured portable maintenance support tool (PMST)—a handheld electronic device similar in size to a personal data assistant—to view processed data transmitted wirelessly from the central data node and then assess structural integrity. The rate at which the information is processed by the nodes and sent wirelessly to the PMSTs is determined by the user, but programmed by Analatom. Once the PMST acquires the data from the sensor nodes, the support tool uses AI protocols to predict impending failures in time for proper action. These AI protocols actually can reprogram the in-place sensors, based on their data output, to upgrade their predictive capabilities. Graphical representations of such AI structural health monitoring data are displayed on the PMST's screen. These graphical representations include color-coded status lights to indicate the levels of corrosion of the object being monitored. PMST sensor data is downloadable to PC workstations where additional prognostic algorithms can help better predict structural health.
PMSTs also can work with any off-the-shelf sensor to analyze a wide variety of data, including corrosion, strain loading, impact, cracking, shock, humidity, and temperature. A PMST processes data in real time, even if it is nonlinear, inexact, or incomplete. No other sensor analyzer can handle such a wide range of input sources and offer real-time processing, according to Analatom company officials.
Analatom is currently selling its sensor technology as a commercial product. Corrosion sensors and PMSTs are built to order. By mid-2009, new production efficiencies are expected to decrease the delivery time of products from one to two months to about one week.
The company hopes to sell its technology to any industry that needs real-time, structural health monitoring, including local, state, and federal transportation departments, bridge designers and erectors, helicopter, ship, and wind turbine manufacturers, trucking and freight companies, and operators of public water systems and natural gas lines.
