DISCOVERY ARTICLES
ROBOTIC TAILS:
HIGH-TECH TAILS MAY
PROVIDE BIO-INSPIRED
SOLUTION TO
ROBOT STABILITY
In the Robotics and Mechatronics
Lab of Pinhas Ben-Tzvi, associate
professor of mechanical engineering,
the tail has become a captivating
solution for the problem of bipedal
and quadrupedal robot stabilizing and
maneuvering.
“If you’ve seen robotic quadrupeds,
they are very big and very expensive,
with articulated legs incorporating
multiple degrees of freedom,” said
Ben-Tzvi. “The machines use the
leg’s multiple degrees of freedom to
maneuver and stabilize so if they are
pushed from the side, the legs adjust
like a human to keep it from falling.”
The problem is that with legs so
complex, they are large and very
expensive, requiring additional joints
and motors, as well as complex control
algorithms and increased computational
load. With the addition of a robotic tail,
Ben-Tzvi believes the legs can get much
simpler, and the robot lighter, easier to
design, and less expensive.
“We can make legs with a single
degree of freedom, and one motor per
leg that will allow the entire mechanism
to run forward, but really fast,”
explained Ben-Tzvi. “The legs take care
of the locomotion, and the tail takes
care of stabilization and maneuvering.
By decoupling the purposes, we can
scale back the complicated legs to
make the system much simpler, lighter,
more agile, and less expensive.”
The tail works by exerting forces and
moments on the robot in six degrees
of freedom: forces along the x, y,
and z directions and moments about
those directions. Ben-Tzvi and his
students are mapping the forces and
moments generated by the tail motion
in an effort to provide stability and
maneuvering. The tails are flexible,
self-contained and made of the
mechanisms that provide the structural
backbone of the tail. Actuators and
sensors in the tail joints measure
position, velocity, and acceleration.
7