17-11-2012, 02:42 PM
Biologically Inspired Intelligent Robotics Using Artificial Muscles
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Abstract
Humans throughout history have always sought to mimic the appearance, mobility, functionality,
intelligent operation, and thinking process of biological creatures. This effort have led in recent
years to advancements in artificial muscles, artificial intelligence, artificial vision and many
other biologically inspired fields. Artificial muscles, which are the moniker for electroactive
polymers (EAP), are one of the newest among these technologies. To reach the level of making
EAP materials actuators of choice for engineers there are many aspect of the field that need to be
brought to established levels towards making robust devices. These aspect are the infrastructure
for the field of EAP and they range fi-om comprehensive understanding the mechanism from the
chemical and electro-mechanical levels thm effective fabrication and processing the materials as
actuators. In 1999, the author posed a challenge to the worldwide research and engineering
community to develop a robotic arm that is actuated by artificial muscles to win an arm wrestling
match against a human opponent. The presented paper will cover the current state-of-the-art and
challenges to making biomimetic robots using artificial muscles
INTRODUCTION
Robotics has been an evolution of the field of automation where there was a desire to emulate
biologically inspired Characteristics of manipulation and mobility. In recent years, significant
advances have been made in robotics, artificial intelligence and others fields allowing to make
sophisticate biologically inspired robots [Bar-Cohen and Breazeal, 20031. Using these
advances, scientists and engineers are increasingly reverse engineering many animals'
performance characteristics. Biologically inspired robotics is a subset of the interdisciplinary
field of biomimetics. Technology progress resulted in machines that can recognize facial
expressions, understand speech, and perform mobility very similar to living creatures including
walking, hopping, and swimming. Further, advances in polymer sciences led to the emergence
of artificial muscles using Electroactive Polymer (EAP) materials that show functional
characteristics remarkably similar to biological muscles.
Making creatures that behave like the biological model is a standard procedure for the
animatronics industry that is quite well graphically animates the appearance and behavior of such
creatures. However, engineering such biomimetic intelligent creatures as realistic robots is still a
challenge due to the need to physical and technological constraints. Making simple tasks such as
hopping and landing safely without risking damage to the mechanism, or making body and facial
expression of joy and excitement, which are very easy tasks for human and animals to do, are
extremely complex to engineer.
BIOLOGY AND NATURE AS INSPIRING MODELS
Evolution over millions of years in nature led to the introduction of highly effective and power
efficient biological mechanisms. Imitating these mechanisms offers enormous potentials for the
improvement of our life and the tools we use. Humans have always made efforts to imitated
nature but the improvement in technology it is becoming easier to make such adaptation.
The introduction of the wheel has been one of the most important invention that human made
allowing to traverse great distances and perform tasks that would have been otherwise
impossible within the life time of a single human being. While wheel locomotion mechanisms
allow reaching great distances and speeds, wheeled vehicles are subjected to great limitations
with regards to traversing complex terrain with obstacles. Obviously, legged creatures can
perform numerous functions that are far beyond the capability of an automobile. Producing
legged robots is increasingly becoming an objective for robotic developers and considerations of
using such robots for space applications are currently underway. Making miniature devices that
can fly like a dragonfly; adhere to walls like gecko; adapt the texture, patterns, and shape of the
surrounding as the octopus (it can reconfigure its body to pass thru very narrow tubing); process
complex 3D images in real time; recycle mobility power for highly efficient operation and
locomotion; self-replicate; self-grow using surrounding resources; chemically generate and store
energy; and many other capabilities are some of the areas that biology offers as a model for
science and engineering inspiration. While many aspects of biology are still beyond our
understanding and capability, significant progress has been made. Adapting mechanism of
nature may be more effective to make by mimicking the functional capability rather than fully
copying the mechanisms. The airplane is one such an example where human made attempts over
to fly like birds over many centuries. There is no doubt that human has significantly surpassed
biology in flying way higher, faster and perform function that are far beyond any creature
capability.
ARTIFICIAL MUSCLES
Muscles are the key to the mobility and manipulation capability of biological creatures and when
creating biomimetic it is essential to create actuators that emulate muscles. The potential to
make such actuators is increasingly becoming feasible with the emergence of the electroactive
polymers (EM), which are also known as artificial muscles [Bar-Cohen, 20011. These materials
have functional similarities to biological muscles, including resilience, damage tolerance, and
large actuation strains. Moreover, these materials can be used to make mechanical devices with
no traditional components like gears, and bearings, which are responsible to their high costs,
weight and premature failures. The large displacement that can be obtained with EAP using low
mass, low power and, in some of these materials also low voltage, makes them attractive
actuators. The capability of E M S to emulate muscles offers robotic capabilities that have been
in the realm of science fiction when relying on existing actuators.
BIOMIMETIC ROBOTS USING EAP
Mimicking nature would significantly expand the functionality of robots allowing performance
of tasks that are currently impossible. As technology evolves, great number of biologically
inspired robots actuated by EAP materials emulating biological creatures is expected to emerge.
The challenges to making such robots can be seen graphically in Figure 2 where human-like and
dog-like robots are shown to hop and express joy. Both tasks are easy for humans and dogs to do
but are extremely complex to perform by existing robots.