TECHNOLOGY

—by Richard Mandel

Robo-flytrap. To survive without human help, a robot needs to be able to generate its own energy. To this end, Chris Melhuish and his team of robotics experts at the University of the West of England in Bristol are developing a robot that catches flies and digests them in a special reactor cell that generates electricity. Called EcoBot II, the robot is part of a drive to make “release and forget” devices that can be sent into dangerous or inhospitable areas to carry out remote industrial or military monitoring of, say, temperature or toxic gas concentrations. Sensors feed a data logger that periodically radios the results back to a base station. The robot’s energy source is the polysaccharide sugar called chitin, a major component of a fly’s exoskeleton. EcoBot II digests the flies in an array of eight microbial fuel cells (MFCs), which employ bacteria from sewage to break down the sugars. In the process, the bacteria release electrons that are harnessed to create an electric current. The MFCs are the first in the world to employ the gas (O₂) diffusion cathode, which in terms of autonomy is extremely important. In the MFC cathode, O₂ from free air acts as the oxidising agent to take up the electrons and protons to produce H₂O. This process closes the circuit and keeps the system balanced. In tests, EcoBot II traveled for five days on just eight fat flies — one in each MFC. Previous efforts to use carnivorous MFCs to drive a robot included an abortive UWE effort: the Slugbot. This unit was designed to hunt slugs on farms by using imaging systems to spot and grab the pests, and then deliver them to a digester to produce methane for a fuel cell. The electricity generated would have been used to charge the Slugbot when it arrived at a docking station. However, the methane-based system took too long to produce power, and the team recognized a different configuration was necessary. (Another earlier project that used MFCs was developed by the University of Florida, and appeared of Technology Spotlight page of our September 2000 issue. The difference in this system is that the U of F ’bot needed to be fed sugar cubes, while EcoBot II works on unrefined fuel.) In its present form, EcoBot II still has to be manually fed fistfuls of dead bluebottles, but the ultimate aim of the UWE team is to make the droid predatory, using sewage as bait.

University of the West of England,
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In-situ FEA. Countless steel and aluminum equipment structures carry or bear heavy loads in construction, transportation, and other applications. The unknown variability of these loads during use pose significant risks, and as a result the structures tend to be over-designed, expensive, and wasteful of resources. From MicroStrain Inc., Williston, VT, comes an announcement of a project to provide wireless sensor information in real-time on the condition of equipment and structures. The three-year development program, called Structural Health Integrated Electronic Life Determination, or SHIELD system, will consist of wireless sensors attached to different parts of a structure to collect data continuously on actual use, fatigue damage, cracks and other parameters, and hardware and software to analyze these data. Low-cost, low-power sensors will be developed based on micro-electromechanical systems. Hardware will be developed for high-speed damage calculations, and software will be written to determine accurately the loads of dynamic systems. Neural networks will supplement real-time dynamic structural analysis. If successfully developed and deployed, the new technology will improve safety and reduce losses by predicting potential catastrophic failures, enhance productivity through optimized structural design and operation, and reduce maintenance and repair costs through monitoring of damage accumulation. In addition to the initial applications in mining and construction equipment, the SHIELD system could be used to monitor trucks, bridges, buildings, aircraft, railways, and ships. To improve risk and failure management and structural efficiency, a concurrent joint venture led by Caterpillar was set up to develop and demonstrate prototype sensor and analysis technologies, to determine in real time the condition and remaining functional life of large pieces of equipment and/or structures. Other project participants are Motorola Inc. (Schaumburg, IL) and Native American Technologies (Golden, CO). The University of Illinois at Urbana-Champaign (Urbana, IL) and Drexel University (Philadelphia, PA) will serve as consultants on damage analysis calculations and structural health monitoring, respectively. MicroStrain will contribute expertise and new ideas for next generation wireless strain sensor networks.

MicroStrain Inc.,
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Adhesive mixing. TAH Industries, Robbinsville, NJ, has developed a cartridge platform that eliminates the need for special tools to dispense two-component adhesives. Fitting a standard, single-component caulking gun, the Universal Cartridge stores one component of the adhesive in front of the other, extruding both through the cartridge outlet and into a static mixer simultaneously without sacrificing cartridge capacity and convenience. When the inner cartridge is pushed forward against a stationary rear piston, the rear component is extruded through the center tube and out through the cartridge outlet. As the inner cartridge slides past the rear piston, the front piston is pushed forward, causing the forward component to be extruded concurrently through the cartridge outlet. The cartridge presently is offered in 1:1 and 1:2 mix ratios, with 1:4 and 1:10 under development, and the outlet accepts industry standard static mixers.

TAH Industries,
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