The latest Aqua robot with rubber treaded
legs for walking. Here, a human operator
tethers the robot with a cable for remote
communications and manuevers. The
researchers have just completed
development of a set of six all-purpose legs
[not shown] for land and sea so they don’t
have to change the robot’s legs to go into
the water from the shore.
models, the older models are still useful
and can sometimes be upgraded. “We try
to back port new technologies into older
models when possible, but that is not
always possible,” says Dudek.
Speaking of new technologies, the
greatest advancement is the new smaller,
sleeker body design which allows the
robot to operate more quickly. Researchers
can also pack it into a single pelican case
for easy stowage on planes for flight to
remote water destinations.
The computers are also faster and
higher performance, as are the cameras.
The Kroy has two computers inside and
uses three cameras which study the
environment and help with navigation.
Two of the cameras face forward, the
other one is in the back.
The robot’s software — RoboDevel —
runs on a real-time operating system
called QNX. This software generates the
different gaits or strides the robot needs
to employ on land and under water. It
also operates the servo software.
The robot’s many gaits include one
for very fast strides that are unfortunately
not energy efficient, and others are for
turning, moving laterally, and so on.
The robot’s legs store spring energy
when they bend under a load and this
energy is released as the legs push
forward. This is a critical part of the
robot’s locomotion strategy. When the
robot weighs down on the legs, the
compression of the spring stores energy
that is released, aiding forward
“The swimming and walking functions
are implemented as RHexLib modules. A visual processing
module for Aqua is being developed with VXL as the vision
library,” according to Dudek.
The robot actually runs two operating systems. One of
the computers runs Linux and one runs QNX (which is
similar to Linux). The computer running QNX moves the
legs and tracks their motion. When the robot transitions
from water to shore, it is crucial that the timing is accurate
when changing gaits. The Linux operating system manages
diver-following and long-term planning by the robot.
Through the application of visual servoing, the Aqua
robot can adjust its course based on what it sees. “It can
SERVO 07.2010 11