Humanoid robot
A humanoid robot is a robot with its body shape built to resemble
that of the human body. A humanoid design might be for
functional purposes, such as interacting with human tools and environments, for
experimental purposes, such as the study of bipedal locomotion, or for other
purposes. In general, humanoid robots have a torso, a head, two arms, and two
legs, though some forms of humanoid robots may model only part of the body, for
example, from the waist up. Some humanoid robots may also have heads designed
to replicate human facial features such as eyes and mouths. Androids are
humanoid robots built to aesthetically resemble humans.
Contents
·
7 Notes
was created to be a personal
assistant. It is self-guiding and has limited speech recognition and synthesis.
It can also carry things.
Humanoid robots are used as a
research tool in several scientific areas.
Researchers need to understand the
human body structure and behavior (biomechanics) to build and study humanoid
robots. On the other side, the attempt to the simulation of the human body
leads to a better understanding of it.
Human cognition is a field of study
which is focused on how humans learn from sensory information in order to
acquire perceptual and motor skills. This knowledge is used to develop
computational models of human behavior and it has been improving over time.
It has been suggested that very
advanced robotics will facilitate the enhancement of ordinary humans. See transhumanism.
Although the initial aim of humanoid
research was to build better orthosis and prosthesis for
human beings, knowledge has been transferred between both disciplines. A few
examples are: powered leg prosthesis for neuromuscularly impaired, ankle-foot
orthosis, biological realistic leg prosthesis and forearm prosthesis.
Besides the research, humanoid robots
are being developed to perform human tasks like personal assistance, where they
should be able to assist the sick and elderly, and dirty or dangerous jobs.
Regular jobs like being a receptionist or a worker of an automotive
manufacturing line are also suitable for humanoids. In essence, since they can
use tools and operate equipment and vehicles designed for the human form,
humanoids could theoretically perform any task a human being can, so long as
they have the proper software. However, the complexity of doing so
is deceptively great.
They are becoming increasingly
popular for providing entertainment too. For example, Ursula, a female robot,
sings, play music, dances, and speaks to her audiences at Universal Studios.
Several Disney attractions employ the use of animatrons, robots that look,
move, and speak much like human beings, in some of their theme park shows.
These animatrons look so realistic that it can be hard to decipher from a
distance whether or not they are actually human. Although they have a realistic
look, they have no cognition or physical autonomy. Various humanoid robots and
their possible applications in daily life are featured in an independent
documentary film called Plug & Pray, which was released in
2010.
Humanoid robots, especially with artificial
intelligence algorithms, could be useful for future
dangerous and/or distant space exploration missions, without having the need to turn back
around again and return to Earth once the mission is completed.
Sensors
A sensor is a
device that measures some attribute of the world. Being one of the three
primitives of robotics (besides planning and control), sensing plays an
important role in robotic paradigms.
Sensors can be classified according
to the physical process with which they work or according to the type of
measurement information that they give as output. In this case, the second
approach was used.
Proprioceptive sensors
Proprioceptive sensors sense the position, the
orientation and the speed of the humanoid's body and joints.
In human beings the otoliths and
semi-circular canals (in the inner ear) are used to maintain balance and
orientation. In addition humans use their own proprioceptive sensors (e.g.
touch, muscle extension, limb position) to help with their orientation._
Humanoid robots use accelerometers to measure the acceleration, from
which velocity can be calculated by integration; tilt sensors to
measure inclination; force sensors placed in robot's hands and feet to measure
contact force with environment; position sensors, that indicate the actual
position of the robot (from which the velocity can be calculated by derivation)
or even speed sensors.
Exteroceptive sensors
An artificial hand holding a lightbulb
Arrays of tactels can
be used to provide data on what has been touched. The Shadow Hand uses
an array of 34 tactels arranged beneath itspolyurethane skin
on each finger tip.[3] Tactile sensors also provide information about forces and
torques transferred between the robot and other objects.
Vision refers
to processing data from any modality which uses the electromagnetic spectrum to
produce an image. In humanoid robots it is used to recognize objects and
determine their properties. Vision sensors work most similarly to the eyes of
human beings. Most humanoid robots use CCD cameras as vision sensors.
Sound sensors allow humanoid robots
to hear speech and environmental sounds, and perform as the ears of the human
being. Microphonesare usually used for this task.
Actuators
Actuators are
the motors responsible for motion in the robot.
Humanoid robots are constructed in
such a way that they mimic the human body, so they use actuators that perform
like muscles and joints,
though with a different structure. To achieve the same effect as human motion,
humanoid robots use mainly rotary actuators. They can be either electric, pneumatic, hydraulic, piezoelectric or ultrasonic.
Hydraulic and electric actuators have
a very rigid behavior and can only be made to act in a compliant manner through
the use of relatively complex feedback control strategies. While electric
coreless motor actuators are better suited for high speed and low load
applications, hydraulic ones operate well at low speed and high load
applications.
Piezoelectric actuators generate a
small movement with a high force capability when voltage is applied. They can
be used for ultra-precise positioning and for generating and handling high
forces or pressures in static or dynamic situations.
Ultrasonic actuators are designed to
produce movements in a micrometer order at ultrasonic frequencies (over
20 kHz). They are useful for controlling vibration, positioning applications
and quick switching.
Pneumatic actuators operate on the
basis of gas compressibility. As they are inflated, they
expand along the axis, and as they deflate, they contract. If one end is fixed,
the other will move in a linear trajectory. These actuators are intended for
low speed and low/medium load applications. Between pneumatic actuators there
are: cylinders, bellows, pneumatic engines, pneumatic stepper
motors and pneumatic
artificial muscles.
Planning and control
In planning and control, the
essential difference between humanoids and other kinds of robots (like industrial ones)
is that the movement of the robot has to be human-like, using legged
locomotion, especially biped gait.
The ideal planning for humanoid movements during normal walking should result
in minimum energy consumption, like it does in the human body. For this reason,
studies on dynamics and control of
these kinds of structures become more and more important.
To maintain dynamic balance during
the walk,
a robot needs information about contact force and its current and desired
motion. The solution to this problem relies on a major concept, the Zero Moment Point (ZMP).
Another characteristic of humanoid
robots is that they move, gather information (using sensors) on the "real
world" and interact with it. They don’t stay still like factory
manipulators and other robots that work in highly structured environments. To
allow humanoids to move in complex environments, planning and control must
focus on self-collision detection, path planning and obstacle avoidance.
Humanoids don't yet have some
features of the human body. They include structures with variable flexibility,
which provide safety (to the robot itself and to the people), and redundancy of
movements, i.e. more degrees of
freedom and therefore
wide task availability. Although these characteristics are desirable to
humanoid robots, they will bring more complexity and new problems to planning
and control.
No comments:
Post a Comment