With
renewed interest in moon exploration -- in particular the remote
possibility that deposits of helium-3, believed to be in greater
concentration on the moon, could one day power nuclear fusion power
plants on Earth -- robots might be the ideal solution, especially to
keep the costs down.
And a design from
the German Research Center for Artificial Intelligence (also known as
DFKI) in Bremen, Germany, has landed on the chimpanzee as its model for
unmanned lunar missions.
Quadruped stability
DFKI hopes its design -- called the iStruct Demonstrator and
nicknamed "Charlie"- will capitalize on the inherent stability of the
ape's quadrupedal stance without losing the chimp's versatility in
climbing, grasping and moving over all types of terrain.
"We chose the ape because it allows us to study several locomotion modes," DFKI researcher Daniel Kuhn told CNN.
"For
example, they have quite good quadrupedal walking abilities but they
can also perform stand- up motion and walk on two legs -- their ability
to do this is greater than other animals. This change in posture and
walking form interested us," he said.
Four-legged
locomotion, Kuhn explained, might be stable -- but for speed and
agility on flat ground, bipedal walking has the edge.
The chimp's greatest asset is that it can choose which form of movement best fits the situation.
"They
can choose: if the environment won't let you move in a stable fashion
on two legs they can choose four. When the environment improves, two
legs allows you to get a better view over the field."
Founded by the German space agency DLR, the project has also built Lunar craters in a lab to test the prototype.
"In general, we are very happy with the results," he said. "The robot can walk up and down slopes of up to 20 degrees.
"Currently,
we are studying how to transfer from the four-legged to the two-legged
motion pattern, which is very interesting. This system gives us hints as
to how much deviation there is between the four-legged and the
two-legged walking and how humans evolved to walk on two legs."
Lower body torque
Previously,
most multi-legged robots have been equipped with single-point contact
feet for the sake of simplicity in design and control.
However
the robotic chimpanzee focuses on a sophisticated lomwer limb system
that combines the torque and twist of the chimpanzee's lower body.
And, like a real chimp, the robot's feet and hands have multiple sensors and multiple points of contact.
The
sensors include a pressure sensor array of 43 individual force sensing
resistor (FSR) sensors. It also has six additional FSR-sensors used for
collision detection.
The robot is also
equipped with a distance sensor in the heel to anticipate the heel
strike and two temperature sensors to compensate for the difference in
temperature produced by its own electronics.
Robot with backbone
Its biggest advantage, however, comes from the fact that like a real chimpanzees, it has a spine.
"We
have an actuated spine -- one of the first ever built -- and for us it
was very interesting how the spine influences the motion of the legs,"
Kuhn said. "We need much less activation for the knee -- the knee can be
much lower if we use the spine and it needs less force to move the
robot.
"It's strong enough to walk around and carry its own weight -- and it can carry 20 to 25 kg of additional weight."
Because
of the embedded electronics in the spine, the overall structure can be
used as a 6-axis force-torque sensor, allowing it a range of movement
that replicates human and animal mobility.
Daunting specs
For those designing lunar robots, the list of specifications can be daunting.
Not
only must a robot be able to see, drill, grind, collect and even sieve,
it needs to get around a hostile environment in extreme temperatures
and in a vacuum.
Robots also must offer
the greatest strength and versatility for the least payload and have
the ability to fix problems if something goes wrong.
With
the moon 380,000 kilometers away, there's little margin for error and
Kuhn says it may take three or four generations before the lunar chimp
is completely space proof.
"You have
to use different technologies - you can't use the same electronics that
you use on Earth; they have to be space qualified and space proof.
"What
we are doing is working on integrating more redundancy into the robot.
If something goes wrong then we can rely on different actuators."
Space and other animals
The
chimpanzee is not the only animal that is being studied by DFKI as a
potential model for a lunar robot. Also on the drawing board are plans
for a lunar mantis and a lunar scorpion.
Also at the prototype stage, the advantage of this type of locomotion, Kuhn says, has great potential.
"What
you have is an animal that can stand on four legs, giving it stability,
but can use its front two legs to manipulate objects," he said.
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