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The
Mars Exploration Rovers act as robot geologists
while they are on the surface of Mars.
The mars exploration rover body is called
the warm electronics box, or "WEB" for short,
which is temperature-controlled.
The Pancam Mast Assembly of the Mar exploration
rover acts as a periscope for the science instrument
that is housed inside the rover body for thermal
reasons and to provide height and a better point
of view for the high-resolution color stereo
pair of CCD camera.
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The rover arm (also called the instrument
deployment device, or IDD) holds and maneuvers
the instruments that help scientists get up-close
and personal with Martian rocks and soil.
Much like a human arm, the robotic arm has
flexibility through three joints: the rover's
shoulder, elbow, and wrist. The arm enables
a tool belt of scientists´ instruments to extend,
bend, and angle precisely against a rock to
work as a human geologist would: grinding away
layers, taking microscopic images, and analyzing
the elemental composition of the rocks and soil.
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The Mars Exploration Rover has six wheels,
each with its own individual motor.
The main source of power for each rover comes
from a multi-panel solar array. The power system
for the Mars Exploration Rover includes also
two rechargeable batteries that provide energy
for the rover when the sun is not shining, especially
at night.
The rover has both a low-gain and high-gain
antenna that serve as both its "voice" and its
"ears".
The low-gain antenna sends and receives information
in every direction; that is, it is "omni-directional."
The antenna transmits radio waves at a low rate
to the Deep Space Network (DSN) antennas on
Earth. The high-gain antenna can send a "beam"
of information in a specific direction and it
is steerable, so the antenna can move to point
itself directly to any antenna on Earth. The
benefit of having a steerable antenna is that
the entire rover doesn´t necessarily have to
change positions to talk to Earth.
Not only can the rovers send messages directly
to Earth, but they can uplink information to
other spacecraft orbiting Mars.
The benefits of using the orbiting spacecraft
are that the orbiters are closer to the rovers
than the Deep Space Network antennas on Earth
and the orbiters have Earth in their field of
view for much longer time periods than the rovers
on the ground.
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The
Ranger space robot system includes four manipulators: two 7-DOF
arms for bilateral dexterous manipulation; a 7-DOF manipulator for
grappling at the local worksite; and a 6-DOF arm for positioning
a pair of stereo video cameras giving primary feedback to the remote
operator. A second stereo camera pair mounted on the vehicle centerline
will provide a stable visual reference for free-flight maneuvering,
and ultimately feed a vision system for autonomous vehicle docking.
It is controlled from a ground station at the University of Maryland.
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Ranger Neutral Buoyancy Vehicle (NBV), a neutral buoyancy
version of the system. It incorporated advances in neutral
buoyancy simulation technology, such as active buoyancy
compensators and automatic control of the center of gravity
for fine rotational buoyancy.
With a potential space shuttle launch opportunity, it
also evolved into the
Ranger Telerobotic Shuttle Experiment. The robot was
to be attached to a Spacelab pallet within the cargo bay
of the space shuttle orbiter.
The main application of the Ranger space robot is in
the area of near space assembly & Maintenance. It is
used for satellite inspection, maintenance, refueling, and
orbit adjustment. It is also proficient in operating robotic
tasks under the neutral buoyancy condition. For example,
robotic compatible orbital replacement unit change-out,
complete end-to-end connect and disconnect of electrical
connector, adaptive control for freefalling operation and
station keeping, two-arm coordinated motion, coordinated
multi-location control, and night operations.
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Robonaut is a humanoid robot designed by the Robot Systems Technology
Branch at NASA's Johnson Space Center in a collaborative effort
with DARPA.
The Robonaut project seeks to develop and demonstrate a robotic
system that can function as an Extravehicular Activity (EVA, or
spacewalks) astronaut equivalent.
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Telepresence Control System
To achieve this goal, NASA designs the
telepresence control system to allow a human
operator to control the actions of a remotely
operated robonaut robot. The Robonaut's
telepresence system includes Helmet Mounted
Displays (HMD), force and tactile feedback
gloves and posture trackers. Telepresence
uses virtual reality display technology
to visually immerse the operator in the
robot's workspace. This way the teleoperator
feels as if he or she is in the place of
the robot. Visual feedback is provided by
a stereo display helmet and includes live
video from Robonaut's head cameras. The
HMD provides a view into the robot's environment,
facilitating intuitive operation and natural
interaction with the work site.
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Dexterous Hand
Another critical component of the robonaut
robot is its dexterous hand. Each Robonaut
Hand has a total of fourteen degrees of
freedom. It consists of a forearm which
houses the motors and drive electronics,
a two degree of freedom wrist, and a five
finger, twelve degree of freedom hand.
The hand itself is broken down into two
sections: a dexterous work set which is
used for manipulation, and a grasping set
which allows the hand to maintain a stable
grasp while manipulating or actuating a
given object. This is an essential feature
for tool use. The dexterous set consists
of two 3 degree of freedom fingers (pointer
and index) and a 3 degree of freedom opposable
thumb. The grasping set consists of two,
1 degree of freedom fingers (ring and pinkie)
and a palm degree of freedom. All of the
fingers are shock mounted into the palm.
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