Johns Hopkins University engineers have constructed a hydrodynamics tank 14 feet deep and 25 feet in diameter for testing computer control systems to serve as the brains for deep sea robotic exploration vehicles.

Researchers are using the tank to test the JHU Remotely Operated Vehicle, a small underwater robot developed at the university in Baltimore. The robot's navigation and control systems, also developed at Johns Hopkins, have recently been adapted and enhanced for use in the much larger Jason II vehicle, a new deep-sea oceanographic research
robot operated by the Woods Hole Oceanographic Institution.

The JHU Remotely Operated Vehicle has thrusters to guide its movement and sensors to provide information on its position. Windows on a test tank let researchers observe its performance.

Tethered deep-sea robots are important tools for exploring the deepest part of the ocean, which may lie as far as 11,000 meters below the surface. Human divers can descend safely only about 100 meters. Cables feed power and instructions to the submersibles and receive images and other data.

Navigating and controlling a robotic vehicle from a great distance is particularly difficult, according to Louis Whitcomb, an associate professor in the Johns Hopkins Department of Mechanical Engineering and director of the Dynamical Systems and Control Laboratory.

To determine the submersible's position, researchers have developed a computer system that integrates signals from a dozen on-board sensors to compute the submersible's position and velocity. An operator on the surface uses this information to move the undersea robot in three dimensions.

The control system developed by Whitcomb and his students enables the operator to tell a computer exactly where the submersible should be located; the software then moves the vehicle to that point. Researchers are fine-tuning this system by sending commands over the submersible's tether line to six electric thrusters mounted on its surface.

The U.S. Army National Automotive Center is testing a hybrid hydraulic drive system that it believes can account for significant fuel savings and provide its trucks with a little more power.

A U.S. Army 6x6 FMTV (Family of Medium Tactical Vehicles) equipped with a seven-speed transmission and six-cylinder Caterpillar engine was outfitted with a prototype regenerative drive system from Permo-Drive Technologies of Ballina, New South Wales, Australia. The medium-duty tactical vehicle underwent three weeks of intensive testing.

During these tests, the FMTV dem- onstrated a 27 percent improvement in fuel economy and a 36 percent jump in rapid-acceleration or "dash" capability, according to Paul Chandler, vice president of North American operations for Permo-Drive.

The Permo-Drive Regenerative Drive System uses two hydraulic fluid storage tanks to transfer to a vehicle's driveline energy normally lost as heat during the braking process.

The hybrid hydraulic drive system stores energy normally lost as heat during the braking process in a high-pressure oil tank called an accumulator. The energy is captured as pressurized fluid that can later be released into a vehicle's driveline to reduce fuel consumption or provide additional horsepower on demand, according to Chandler.

The regenerative drive system, or RDS, includes two hydraulic fluid storage devicesÑa high-pressure accumulator tank and a low-pressure reservoir. As braking takes place, energy is captured through the flow of oil from the low-pressure tank to the high-pressure accumulator. A central processor controls the release of pressurized fluid during acceleration.

The RDS weighs approximately 330 pounds. When fully charged, it's able to generate the power equivalent to a 340-horsepower engine with 995 foot-pounds of torque. A prototype will be ready for fleet testing in the fourth quarter of this year, with production planned for 2005, according to Chandler.

The Army has shown continuing interest in the system. "In our modeling and simulation work to date, hybrid-hydraulic systems have shown the potential to provide significant fuel-economy savings for future generations of trucks," said Dennis J. Wend, executive director of the U.S. Army National Automotive Center. Wend pointed out that the Army operates a fleet of nearly 250,000 vehicles that is being transformed into a "lighter, more mobile, and more fuel-efficient fleet."

The National Automotive Center is the Department of Defense and U.S. Army wing focused on collaborative ground vehicle research and development. The center's mission is to link industry, academia, and government agencies in the development and exchange of automotive technologies.

A manufacturer in New Jersey decided to replace the polytetrafluoroethylene bushings on its spherical disc valves with something stronger that resisted deformation better. The PTFE bushings tended to deform under temperatures above 400°F, causing the shutoff disc and shaft to lose their precise setting and resulting in leakage across the seat and disc, said Jim Lenihan, the president of the company, GemcoValve Co. in Middlesex, N.J.

GemcoValve replaced the PTFE for the bushings in its model P21 spherical disk valves with polyetheretherketone, supplied by Victrex USA Inc. of Greenville, S.C.

GemcoValve's P21 spherical disc valve uses a PEEK bushing that resists deformation.

The P21 valves are used in the pharmaceutical and food industries to handle powder bulk solids. Often these solids are in the form of a "wet cake," which has a doughy consistency and moisture content of 30 to 40 percent. Spherical disc valves used in the pharmaceutical industry are often used in feeding large reactors with capacities up to 10,000 liters, or about 2,600 gallons. The raw materials fed into the reactor can be very abrasive and processing often takes 10 to 12 hours, during which the materials and equipment are under high pressure and temperatures.

The bushings on the P21 valve have an eccentric design, so that the seat disc clearance can be adjusted while maintaining an ANSI Class IV shutoff rating for tightness and sealability. Lenihan said that the PEEK was strong and rigid enough to allow the adjustment without deforming. The material is also FDA and USDA compliant, and resists exposure to corrosive environments, solvents, acids, and other volatiles.

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