Engineering News : Page 3 of 10

us The Terminator and Robocop, but it's our nation's universities that give us the silicon-wafer ant and robotuna. Not as glamorous as their film counterparts, these research robots are providing more than entertainment, though-they're supplying a glimpse of the future of locomotion.

The fish. For example, at M.I.T in Cambridge, MA, students are looking to Mother Nature for a better mini-submarine design. Their project began more than three years ago with one goal in mind: develop a better propulsion system for autonomous underwater vehicles, or AUVs.

These robotic submarines can map the ocean floor or find underwater pollution sources. But, "you simply can't put enough batteries on-board for long-term missions like exploring the mid-Atlantic ridge for a couple of months," states ocean-engineering graduate student David Barrett.

Realizing the fish has 160 million years of evolution behind it, researchers used the bluefin tuna as a model. The result was Charlie the Testing Tank Tuna.

About four feet long, this "fish-bot" actually "swishes" its tail to propel itself down M.I.T.'s research tank. The current prototype is attached to a structure that houses all its electronics and guides it down the tank.

While the ultimate goal is a fully autonomous robot, researchers are focusing their efforts on getting the tunafish robot to swim efficiently in a straight line.

The CAT. Meanwhile, at Rensselaer Polytechnic Institute, graduate student Adam Divelbiss is more concerned with wheels than fins.

For his doctoral thesis, Divelbiss sought a mathematical solution to a class of problems where movement is constrained by velocity or acceleration. Parallel parking proved to be an excellent example, he says.

Working with associate professor John T. Wen, Divelbiss designed a quarter-size test vehicle. Called the CATmobile, after the Center for Advanced Technology (CAT), the vehicle pulls two trailers. Divelbiss then wrote a computer program that automatically maneuvers the vehicle into a tight parking space.

The student-professor team equipped the vehicle with sensors to measure steering and jackknife angles, and to predict vehicle position. The feedback system makes real-time corrections, and holds the vehicle to the desired path.

With a few adjustments, the computer system could be used as an on-board assistant to help truck drivers with difficult maneuvers or control a robotic convoy in an automated factory, says Wen.

And the ant. Within Room 717 of Boston University's Research Center, there is a robot being designed that anyone could overlook. Measuring only 3 aem thick, this silicon microrobot, when complete, would be capable of walking in a tripod gait.

The six-legged "ant," which is too small to use motors for leg actuation, moves via a piezo-electric actuator. Most recent developments in its design have been completed by Masters-degree graduate Jayanthy Goli.

So far, piezoelectric ZnO sandwiched between two gold layers for electrodes has been the tested actuator material of choice. Legs were then connected to the actuator, creating a tilting motion when an alternating voltage source is applied.

The micromachine, when complete, could be used in "poison gas detection, DNA sequencing, and even espionage," says Smits.

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