University of Delaware
Office of Public Relations
UpDate - Vol. 16, No. 16, Jan. 9, 1997
Executive robots? Programming may help machines 'think' in space

     Flobot the Robot can already hover on a cushion of air,
manipulating objects with magnetic grippers to simulate hands-off
satellite repairs in space, and the machine may soon learn to
perform such tasks optimally, up to 10 times faster, thanks to a
new algorithm described in the December 1996 issue of the
"Journal of Dynamic Systems, Measurement, and Control."
     Methodical, slow-moving robots- in space, or on the
ground-may become relatively `smart' decision-makers if they're
equipped with optimization algorithms that use "transformations,"
a mathematical device akin to a mental short-cut, says Sunil K.
Agrawal, director of the Mechanical Systems Laboratory at the UD.
     "When a robot tries to grip a satellite in space, it tends
to rotate unpredictably because it is floating freely in a
weightless environment," according to Agrawal, one of 30
promising young researchers to receive a $500,000 Presidential
Faculty Fellow Award from President Bill Clinton in 1994.
"Predicting how a robot will behave in space-and programming it
to perform satellite repairs quickly-is a real challenge."
     That's why Agrawal's research team created Flobot, a
wireless 170-pound robot capable of grabbing a moving object
while hovering over a table. As jets of air are released from a
tank on the robot, it moves over the table and starts searching
for a targeted object. Using an overhead vision system, a master
computer in Agrawal's laboratory tracks the robot and directs its
movements via radio signals, explains graduate student Mahu
Annapragada. Two long arms, each equipped with four motors, latch
onto an uncooperative mock satellite when it moves within range
of the robot's grasp.
     In the past, Agrawal explained, researchers have tried to
simulate the behavior of free-floating space robots by launching
machines into orbit, or by dropping test capsules into a deep
hole in the earth, to mimic weightless conditions. But space-
based experiments are costly, he noted, and test capsules fall so
rapidly inside tunnels that researchers may have a tough time
generating accurate measurements.
     By comparison, Agrawal said, "Flobot is a low-cost
alternative for practicing the tasks involved in repairing a
satellite in space."
     Highly sophisticated robots are now capable of making high-
speed maneuvers while traveling from Point A to Point B, Agrawal
said. To achieve "real-time" control, he added, a robot must
constantly process and update mathematical inputs based on its
current position, taking into account the speed of its movements.
Unfortunately, he said, controlling and optimizing robotic
movements using a classic mathematical tool known as "Lagrange
multipliers" is an extremely computer-intensive task.
     But Agrawal said his new technique of dynamic optimization
using transformations could result in a 10-fold reduction in
calculation time.
     Along with Flobot, Agrawal and his team of six graduate
students are working on robots capable of performing dangerous or
complicated tasks on earth. For example, a Spine Robot, designed
to move like a human spine, could be perfected to serve as a
probe, or perhaps to perform repair-and-retrieval tasks inside
small holes in buildings and tunnels in the ground. Because Spine
Robot's "vertebrae" segments are driven by many independent
motors, Agrawal said, the machine is flexible enough to navigate
narrow, curving spaces.
     Snake Robot, a close cousin of Spine Robot, may prove ideal
for zipping around obstacles on a factory floor, or for entering
potentially hazardous environments. "When we were successful in
developing Spine Robot," Agrawal said, "we added wheels to each
of these individual vertebrae segments to create a Snake Robot.
Compared to some existing robots now being used in factories, we
think Snake Robot may be more adept at carrying objects back and
forth through a cluttered industrial environment, or for
dangerous inspection tasks-say, inside a nuclear reactor."
     A Hopping Robot is now in the preliminary design stage. If
the robot can be programmed to respond to impulses from the
ground, Agrawal said, "we might be able to invent an incredibly
fast running machine."
                                        -Ginger Pinholster