Trevor M. Young (Ed.)\*, "**Innovation in Aeronautics,"** Woodhead
Publishing Limited, UK.

# 

\*Trevor M. Young, Department of Mechanical and Aeronautical
Engineering, University of Limerick, Ireland.

**Chapter 4**: *Biologically inspired technologies for aerospace*

Yoseph Bar-Cohen,

Jet Propulsion Laboratories (JPL)/California Institute of Technology,
Pasadena, CA, USA

[4.1 Introduction 2](#introduction)

[4.2 Biologically inspired or independent human innovation
6](#biologically-inspired-or-independent-human-innovation)

[4.3 Nature as a source of innovation in aerospace
9](#nature-as-a-source-of-innovation-in-aerospace)

[4.4 Biologically inspired mechanisms and systems
14](#biologically-inspired-mechanisms-and-systems)

[4.5 Robotics as beneficiary of biomimetic technologies
20](#robotics-as-beneficiary-of-biomimetic-technologies)

[4.6 Summary -- the challenges and potential development
22](#summary-the-challenges-and-potential-development)

[4.7 Acknowledgement 24](#acknowledgement)

[4.8 References 24](#__RefHeading___Toc216434313)

**ABSTRACT**

Thru evolution over billions of years, nature addressed its challenges
by trial and error and came up with inventions that work well and last.
For its experiments nature employs principles of physics, mechanical
engineering materials science, chemistry,, and many other fields of
science and engineering. Nature inventions inspired human achievements
in developing effective methods, materials, processes, structures,
tools, mechanisms, algorithms, and systems. The field of technology that
is based on inspiration of nature is known as Biomimetics and it offers
enormous potential for many exciting future capabilities. There are
numerous examples of biomimetic successes including making simple
copies, as the use of fins for swimming. Others examples involved
greater mimicking complexity including the mastery of flying that became
possible only after the principles of aerodynamics were better
understood. Some commercial implementations of biomimetics, including
robotic toys, are increasingly appearing and behaving like living
creatures. More substantial benefits of biomimetics include the
development of prosthetics that closely mimic real limbs and
sensory-enhancing microchips are used to interface them with the human
brain to assist in hearing, seeing, and controlling instruments. The
focus of this Chapter is on the aerospace related innovation that was
inspired by nature and it covers various examples, the potentials and
the challenges.

**Keywords:** Aerospace, Robotics, Biomimetics, EAP, Biologically
inspired technology.

# 4.1 Introduction

Nature is a self-maintained experimental laboratory that is addressing
its changing challenges through the trial and error process of
evolution. In performing its experiments every field of science and
engineering nature is involved with testing principles of physics,
chemistry, mechanical engineering, materials science, mobility, control,
sensors, and many others. Also, the process involves scaling from nano
and macro, as in the case of bacteria and virus, to the macro and mega,
including our life scale and the whales. The extinction of the dinosaurs
may suggest that mega-scale land living animals are unsustainable form
of life as opposed to mega-size sea creatures such as the whales.
Observing and studying the capabilities of living creatures suggest
numerous possibilities that can be adapted to solve and support human
needs. Nature has always served as a model for mimicking and inspiration
to humans in the efforts to improve the way we live. The subject of
copying, imitating, and learning from biology is also known as
Biomimetics and it represents the studies, imitation and inspiration of
nature\'s methods, designs and processes \[Bar-Cohen, 2005; Benyus,
1998; Schmitt, 2003; Vincent 2001; Vogel 2003\]. Some of the
capabilities were copied from nature while for others it served as an
inspiring model. Flying was inspired by insects and birds using human
developed capabilities, whereas the design and function of fins, which
divers use, was copied from the legs of water creatures like the seal,
goose and frog. Scientific approaches are helping humans understand
nature's capabilities and the associated principles resulting in the
development of effective tools, algorithms, approaches and other
capabilities to benefit mankind. The ultimate goal of biomimetics may be
the development of life-like robots that appear and function like
humans. Efforts are currently underway to develop such robots and
impressive capabilities have already been reported where humanlike
robots can conduct conversation with limited vocabulary, respond to body
and facial expressions as well as avoid obstacles while walking and
others \[Bar-Cohen and Hanson, 2009\]. The focus of this chapter is on
the biologically inspired innovation in aerospace.

In general, nature's materials and processes are far superior to
man-made ones. The body of biological creatures is a laboratory that is
processing chemicals acquired from the surrounding and produces energy,
construction materials, multifunctional structures and waste \[Mann,
1995; Nemat-Nasser et al. 2005\]. Some of the capabilities of nature's
materials include self replication, reconfigurability, self-healing, and
balancing the content of various chemicals including the pH of its
fluids as well as its temperature and pressure. Recognizing the
advantages of these materials, for thousands of years, humans have used
them as sources of food, clothing, comfort, construction and many other
applications. These materials include fur, leather, honey, wax, milk and
silk \[Carlson et al. 2005\]. The need to make these materials in any
desired quantity led to developing approaches of enhancing their
production from the related creatures as well as producing imitations.
Many man-made materials are processed by heating and pressurizing, and
this is in contrast to nature which uses ambient conditions. Materials,
such as bone, collagen or silk are made inside the organism's body using
nature friendly processes with minimal waste and the resulting strong
materials are biodegradable and recyclable by nature.

Besides the multifunctional structures that makes up biological
creatures they also have the capability to produce structures using
materials that they make or pick up from the surrounding. The skeleton
of animals' body is quite marvelous -- it is able to support enormous
physical actions even though it is not a rigid structure. Also, the
produced structures (such as the nest and cocoon's shell and underground
tunnels that gophers and rats build) are quite robust and support the
structure's required function over the duration that it is needed. Often
the size of a structure can be significantly larger than the species
that builds it, as is the case of the spider's web. An example of a
creature that has a highly impressive engineering skill is the beaver,
which constructs dams as its habitat on water streams. The honeycomb is
also an inspiring structure and it provides the bees a highly efficient
packing configuration \[Gordon, 1976\]. Using the same configuration,
the honeycomb is used to create aircraft structures benefiting from the
low weight and high strength that is obtained. Even plants offer
inspiration, where mimicking the adherence of seeds to animals\' fur led
to the invention of the Velcro and to numerous applications including
clothing and electric-wires strapping.

The development of biomimetic systems and devices is supported by a
growing number of biologically inspired technologies including
artificial intelligence that mimic the control of biological systems
\[Amaral et al., 2004; Hecht-Nielsen, 2005; Serruya et al., 2002\]. The
invention of the wheel made the most profound impact on humans' life
allowing traversing enormous distances and performing various tasks that
otherwise would have been impossible to perform within the life time of
a single person. While the wheel enabled enormous capabilities it has
significant limitations when used for mobility in complex terrains that
have obstacles. Obviously, legged creatures can operate in many such
conditions and far superior ways than an automobile. Legged-robots are
increasingly becoming an objective for the developers of robotic
machines and these include even humanlike ones \[Bar-Cohen and Breazeal,
2003; Bar-Cohen and Hanson, 2009\]. Generally, the mobility of legged
mechanisms currently is being done via motors. While motors have
numerous advantages, since they require gear they are relatively heavy,
structurally complex and have many potential points of failure. Advances
in electroactive polymers (EAP), also known as artificial muscles, are
expected to enable new possibilities for legged robotics with the
potential of turning science fiction ideas into engineering applications
\[Bar-Cohen, 2004\].

As a model for inspiration, it is important to remember that Nature
solutions are driven by survivability of the fittest and these solutions
are not necessarily optimal for the technical performance. Effectively,
all organisms need to do is to survive long enough to reproduce. Living
systems archive the evolved and accumulated information by coding it
into the species' genes and passing the information from generation to
generation through self replication.

There are great benefits to better understand how nature marvels work
and how to adapt them in human made mechanisms. These include such
capabilities as:

-   The dragonfly flight performance in air flying backwards, as well as
    stopping and starting flight in air using their relatively small
    body \[Huang and Sun, 2007\].

-   The toughness of spider silk and its ability to produce the silk at
    room temperatures and pressure conditions \[Trotter, 2000\].

-   The navigation capability of the Monarch butterfly migration of
    great distances and reaching targeted locations at which as an
    individual it has never been before. This information is coded in
    their genes of its quite small body size \[Sauman et al., 2005\].

-   The strength of seashells that is quite enormous even though it is
    made of calcium carbonate that effectively is a soft material also
    known as chalk \[Yang, 1995\].

-   Our ability to identify people whom we have not seen for many years
    and that have chanced appearance enormously.

The above list is only a small number of examples and covering them all
can be an enormous task and the challenge to adapt them can even be much
more complex. This Chapter examines various examples that are relevant
to aerospace.

# 4.2 Biologically inspired or independent human innovation

Nature and its biological systems have been on Earth many billions of
years before humans reached the level of intelligence that was enough to
start making their own tools. In the effort of humans to become domestic
and minimize the dependence on luck and their harvesting of the
surrounding resources, they started seeking to improve the way they
live. Observing nature was part of their daily life and it inspired them
with ideas of how to acquire and handle food, how to protect themselves
and their resources as well as many other things that were essential to
their way of life.

One may wonder how inspiring on humans' innovation have been the various
creatures that lived in their neighborhoods. The presence of spiders in
humans' habitats should have had some inspiring role on making such
things as wires, ropes, nets, sieves, screens and woven fabrics. One
cannot avoid seeing the similarity of a spider web and the fishing net
or the screen in screen-doors or even the kitchen sieve as shown in
Figure 1. Beside the sieve that may have been inspired by seeing
creatures that are widely present in human habitats, another application
to food handling is the tong and it has been probably inspired by the
beak of birds as shown in Figure 2.

Figure 1: The spider web has been probably the inspiring design for
numerous human made tools. From top left to right: spider web, net, and
screen door. Bottom: kitchen sieve.

Figure 2: The tong may have been likely inspired by the beak of birds
and the way they grab food.

From another angle on the subject of biomimetics one may wonder if all
the inventions and tools that are commonly used by humans were inspired
by nature or, maybe, it was just a coincident that the solution ended
having similar features. An example may include the honeycomb that looks
very much the same in the nature and the technology versions. In the
case of the bees, the honeybee serves as a highly efficient packing
container for their off-springs and food storage when their eggs hatch.
On the other hand, the honeybee in aircraft structures provides a highly
efficient space filler of various parts that are lightweight and have
great strength. Also, it is interesting to notice that many of the
mammals are 4 legged creatures and most of our furniture, such as chairs
and tables, are supported by 4 legs (see an illustration of this point
in Figure 3**)**. It is hard to believe that all the human made
solutions were pure inventions of individuals who ignored what they have
seen in nature and came up with them on their own.

Roboticists are well aware that making robots operate with legs
significantly increases their capability and mobility in complex
terrains. In recent years, there are increasing efforts to create legged
robots for various applications including space and military and
examples are shown in Figure 4 and Figure 5.

Figure 3: One may wonder if the 4-legs of most animals have been an
inspiring model for the furniture like chairs and tables.

Figure 4: Military application of legged robotics.

Figure 5: Examples of legged robots that were developed at JPL for space
application. Future robots may climb mountains and perform lifelike
functions. Courtesy of JPL/Caltech/NASA.

# 4.3 Nature as a source of innovation in aerospace

The field of aerospace as we know it today was inspired by the insects
and birds ability to fly using human developed technology (Figure 6).
The enormously huge number of flying capable species suggests that
nature has extensively "experimented" with aerodynamics and has been
quite successful. Birds are able to maneuver in flight with quite
amazing capabilities as well as while flying carry prey that can be
quite large and heavy compared to their body. They can even catch preys
while flying including, for example, a running rabbit or swimming fish
and they are able to predict their path intersection with the hunted
creature. This capability to hunt while the hunter and the hunted
creatures are both moving fast (running, flying, or swimming) is
increasingly the capability of military weapons allowing tanks to
destroy a moving vehicle while they are both moving fast. Also, missiles
are used to hit enemy fighter aircraft or other missiles by tracking the
moving target and either adjust the direction in flight or aim at the
moment of launch.

Figure 6: Inspired by nature and aerodynamic principles lead to the
flying capabilities of aircraft as the supersonic passenger plane, the
Concord, which is shown on the right. Photographed by the author at the
Boeing Aerospace Museum, Seattle, WA.

Another form of biologically inspired flight is under consideration for
potential future NASA mission at the Ohio Aerospace Institute (Figure
7). This study is taking into consideration that flying on Mars is much
more difficult than on Earth due to the low air pressure and therefore
it is necessary to operate within a very low Reynolds number regime. In
addition to this restriction one needs to take into account the
practical size limitations of a vehicle that can be deployed from Earth.
An entomopter vehicle was recently proposed that uses biomimetic
configuration
\[<http://www.niac.usra.edu/files/studies/abstracts/448Colozza.pdf>\]
and circulation control techniques to achieve substantially higher lift.
The concept is based on the use of a micro-scale vortex at the wing's
leading edge as determined in 1994 by Charles Ellington of the
University of Cambridge \[Scott, 1999\]. Taking advantage of the lower
gravity on Mars one may be able to develop an insect inspired flying
machine at a size of a meter. For power the wing will be covered with
flexible solar cells throughout the structure (see bottom left of Figure
7). Under a DARPA sponsored study researchers at the Georgia Tech
Research Institute have preliminary confirmed that this concept may be
feasible for operation on Mars possibly allowing the vehicle to take
off, fly slowly or hover, and land.

Figure 7: A flying mechanism that emulates the bird was proposed for
planetary exploration missions. Courtesy of Anthony Colozza, Ohio
Aerospace Institute.

Wagging the tail is leading form of propulsion in water and many of sea
creatures are able to develop significant speeds of swimming. Inspired
by this propulsion method and using balloon design, with helium for
operation in air, researchers at EMPA, Switzerland, Duebendorf,
Switzerland, in collaboration with the Institute of Mechanical Systems
of ETH, Zürich, Switzerland, are currently developing such a flying
vehicle \[Michel et al., 2007\]. The project objective is to use
electroactive polymers emulating muscles to produce a lighter-than-air
vehicles. In the first phase, a blimp was developed that has its fins
bent by EAP based actuators to the left and right allowing steering the
blimp. The goal is to develop a novel bionic propelled blimp that is
operated like a fish with tail wagging capability. For this purpose,
fluid dynamics, structural mechanics, and flight performance are
explored with systematic experimental studies. The commercial
application of this technology is the development of larger blimps for
use in transportation, observation and reconnaissance, as well as
stratospheric platforms.

Figure 8: Photographic view of the EAP activated blimp (the black strips
are dielectric elastomer EAP). Photographed by the author at the SPIE's
2008 EAPAD Conference.

Figure 9: A graphic view of the envisioned EAP activated blimp that is
propelled like a fish. Courtesy of Silvain Michel, EMPA - Materials
Science & Technology, Duebendorf, Switzerland.

The dragonfly is an incredible flying insect that can maneuver in air at
relatively high speeds. Its capability has been under studies for many
years in an effort to adapt or inspire aeronautic innovation and
solution to existing problems \[Huang and Sun, 2007\]. The dragonfly
adjusts the effects of high G on its body during its flight and rapidly
maneuvers using liquid-filled sacs that surround its cardiac system.
This method has inspired the Swiss company, Life Support Systems, to
develop an anti-G suit that allows pilots to fly at high mach speeds
with significantly lower effects on their ability to stay coherent. The
developed liquid-filled suit is called \"Libelle,\" which means in
German dragonfly
\[[http://www.lssag.ch/website%2003%2014.html](http://www.lssag.ch/website 03 14.html)\].
Tests of the Libelle suit have shown promise as far as the advantages
over the pneumatic (compressed air) anti-G suits and they are being
tested at various air forces. 

Plants use many method of dispersing their seeds including being blown
in the wind and being shaped with aerodynamic configuration to enable
the largest traveled distance. Thus, the plant species reduce the danger
of crowding of the specific type of plant in the same local area that
may cause competing over the same resources as well as being subjected
to the same environmental risks that possible endanger the survival.
There are various aerodynamic configurations of seeds and an example is
shown in Figure 10 where the seed of the tree Tipuana tipu (about 6.5-cm
long) has a wing that propels it in the wind. It is also interesting to
mention the tropical Asian climbing gourd Alsomitra macrocarpa that is a
tree with a relatively large seed having a 13-cm wingspan. The flight of
the latter seed resembles a boomerang and it is capable of gliding in
wide circles through the rain forest. One may see quite a similarity of
these seeds and helicopter blades and it is most likely have been an
inspiring design for many aerodynamic parts of aircraft and other human
made flying machines.

Another aerospace related area that is benefiting from biomimetics is
the design and development of potential alternatives for planetary
landing of rovers and landers on planets with atmospheres (such as Mars
and Venus). Adapting such designs may offer better alternative for the
use of a parachute on Mars and possibly a better ability to steer the
landing hardware at selected sites. Some of the issues that are being
studied include the determination of the appropriate vehicle size, mass
distribution and platform shape to assure stable autorotation and
scalability from operation on Earth to performance on Mars.

Figure 10: Seeds of the Tipuana tipu, which has aerodynamic shape for
dispersion by the wind.

The tumbleweed is another plant that offered an inspiring design for
planetary mobility that is powered by wind \[Wilson et al., 2006\].
Generally, winds are blown throughout Mars and they provide an
attractive source of mobilizing a rover by mimicking tumbleweed. As
shown in Figure 11, the tumbleweed has inspired a futuristic lander that
could one day be used as a vehicle for mobility on Mars for traversing
great distances with minimal use of power. At NASA Langley, using
three-dimensional dynamic modeling and simulations \[Shouthard et at.,
2007\] has shown that dispersion and exploration of Mars with Tumbleweed
rovers is feasible. A likely mission scenario involves an organized
search for geologically interesting features using a group of rovers
with heterogeneous sensor packages. A tumbleweed rover can potentially
travel longer distances and gain access to areas such as valleys and
chasms that previously were inaccessible. Varying the location of the
mass imbalance is one of the methods currently under consideration for
controlling the motion of wind-blown tumbleweed like rover.

Figure 11: The tumbleweed (left) offered an inspiration for a futuristic
design of a Mars rover (right). The right hand figure is used under a
courtesy of NASA.
[**http://smart-machines.blogspot.com/2007/04/nasas-tumbleweed-inspired-rovers-for.html**](http://smart-machines.blogspot.com/2007/04/nasas-tumbleweed-inspired-rovers-for.html)

# 4.4 Biologically inspired mechanisms and systems

Making aerospace structures can benefit greatly if they could be made of
materials that have nature's characteristics of self-healing, self
replication, reconfigurability, chemical balance, durability and
multi-functionality. The advantages of biological and botanical
materials were well recognized by humans and were used for many
applications \[Carlson et al. 2005\]. Learning how to process
biologically inspired materials can make our choices greater and improve
our ability to create recyclable materials that can better protect the
environment. Mimicking nature materials will also benefit humans in many
other ways including the development of more life-like prosthetics,
where increasingly artificial parts such as hips, teeth, structural
support of bones and others are being produced. There are also many
mechanisms that were biologically inspired including:

[Ground penetration as a gopher and a crab]{.underline} -- Since 1997,
the author, members of his Group at JPL, and engineers from Cybersonics,
Inc., have been involved with research and development of sampling
techniques for future in-situ exploration of planets in the Universe.
The developed techniques are mostly driven by piezoelectric actuators
and the Ultrasonic/Sonic Driller/Corer (USDC) in particular \[Bao et
al., 2003; Bar-Cohen et al., 2005a; Bar-Cohen et al., 2005b\]. The
general configuration of the USDC allows it to penetrate sub-surfaces to
a depth that is no longer than the length of the bit since the other
parts are larger in diameter. In order to reach greater depth with less
restrictions of the depth, two models of deep drills were conceived that
were inspired by the gopher and sand-crab \[Bar-Cohen et al., 2005b\]. A
piezoelectric actuator induces vibrations that impacts the medium that
is in contact and the mechanism that consists of a bit with a diameter
which is the same or larger than the actuator. The device that emulates
the biological gopher is lowered into the produced borehole, cores the
medium, breaks and holds the core, and finally the core is extracted
onto the surface. This Ultrasonic/Sonic device can be lowered and raised
from the ground surface via cable as shown in Figure 12. This device was
called the Ultrasonic/Sonic Gopher and it was designed analogously to
the biological gopher that digs into the ground. It removes the loose
soil out of the underground tunnel that it forms, bringing it to the
surface and resumes the process to reach great depths. The
Ultrasonic/Sonic Gopher was developed to the level of a prototype and
demonstrated at Mount Hood and in Antarctica to perform its intended
function. Further, the Ultrasonic/Sonic Crab design emulates the sand
crab, which shakes its body to penetrate sand on beaches. This device
uses mechanical vibrations on the front surface of the end-effector to
penetrate media that consist of loose soil, sand, or particulates. The
Ultrasonic/Sonic Crab was not produced yet however its implementation is
not expected to pose major technical challenges.

[Pumping mechanisms]{.underline}: Nature uses many pumping mechanisms
that have inspired human made mechanisms. The most common pumps are
peristaltic pumping, where liquids are squeezed in the required
direction. The lungs pump air in tidal process using the diaphragm that
allows us to breath. Pumping via valves and chambers that change volume
is found in human and animal hearts, where the chambers expand and
contract to allow the flow of the blood. Just like in mechanical pumps,
the flow of the blood is critically dependent on the action of the
valves in the heart.

Figure 12: Biologically inspired ground penetrators: Left - the
Ultrasonic/Sonic Crab; and Right -- the Ultrasonic/Sonic Gopher.

[Artificial muscles:]{.underline} Muscles, which are both compliant and
linear in behavior \[Full and Meijer, 2004\], are the actuators of
biological systems allowing all our physical movements. Emulating the
characteristics of muscles is important allowing for making robots that
function with lifelike performance. The actuators that are closest to
emulate natural muscles are the electroactive polymers (EAP), which have
emerged in recent years and gained the name "artificial muscles"
\[Bar-Cohen., 2004\]. There are many types of EAP materials known today
and most of them have emerged in the 1990s. Unfortunately, they are
still not generating sufficient forces to perform significant tasks such
as lifting heavy objects.  In order to help advancing the field rapidly,
the author initiated and organized in March 1999 the first annual
international EAP Actuators and Devices (EAPAD) Conference \[Bar-Cohen,
1999\].  This conference is held annually by the technical society SPIE
as part of its Smart Structures and Materials Symposium. At the opening
of the 1^st^ Conference, he posed a challenge to the worldwide
scientists and engineers to develop a robotic arm that is actuated by
artificial muscles to win an [armwrestling match against a human
opponent](http://ndeaa.jpl.nasa.gov/nasa-nde/lommas/eap/EAP-armwrestling.htm).
The icon of the challenge can be seen in Figure 13 illustrating the
wrestling of human with robotic arm driven by artificial muscles.

Figure 13: The icon of the armwrestling challenge for artificial muscles
match against human.

On March 7, 2005, the author organized the first arm-wrestling match
with human (17-year old high school female student) as part of the
EAP-in-Action Session of the SPIE\'s EAPAD Conference. In this contest,
three EAP actuated robotic arms participated and the girl won against
all three (see Figure 14). Following this match in the 2^nd^ contest,
rather than wrestling with a human opponent, the contest consisted of
measuring the arms performance and comparing the results.  A measuring
fixture was used to gauge the speed and pulling force.  To establish a
baseline for comparison, the capability of the above student was
measured first and then three participating robotic arms were tested. 
This 2nd Artificial Muscles Armwrestling Contest was held on Feb. 27,
2006, and the results have shown two orders of magnitude lower
performance of the arms compared to the student. In a future conference,
once advances in developing EAP actuated arms lead to sufficiently high
force, a professional wrestler will be invited for another human/machine
wrestling match.

Figure 14: The robotic arm driven by artificial muscles, made by
Virginia Tech students, is being prepared for the 2005 match against the
human opponent.

[Inchworm motors]{.underline}: Another form of actuation that was
biologically inspired is the movement of the biologic inchworm, which is
a caterpillar of a group of moths called *Geomeridae*. Emulating the
mobility mechanism of this larva or caterpillar led to the development
of high precision motors and linear actuators that are known as
inchworms. The forces that are generated by the commercial types of
inchworms can reach over 30-Newtons with zero-backlash and high
stability. As opposed to biological muscles, the piezoelectric actuated
inchworms are involved with zero-power dissipation when holding
position. Inchworm mechanisms have many configurations with the basic
principle of using two brakes and an extender. These motors perform
cyclic steps where the first brake clamps onto the shaft and the
extender pushes the second brake forward. Clamping the second break and
stretching the extender allows making the first step that is then
repeated as many times as needed. Inchworm motors were used already in
the Telesat (NASA mission) in the mid-1980s allowing for high precision
articulation in the range of nanometers.

[Bio-Sensors]{.underline}: It is well recognized that sensors are a
critical part of any system allowing it to monitor its functions and
respond to the operation conditions as needed. Sensors emulate the
senses in biological creatures, which provide inputs to the central
nervous system about the environment around and within their body and
the muscles are commanded to action after analysis of the received
information \[Hughes, 1999\]. Biological sensory systems are extremely
sensitive and limited only by quantum effects \[Bialek, 1987; Bar-Cohen,
2005\]. Sensors are widely used and it is not possible to imagine
effective operation of any system without them. Pressure, temperature,
optical and acoustical sensors are widely in use and continuously being
improved in terms of their sensing capability while reducing their size
and consumed power. The eye is emulated by the camera, the whiskers of
rodents are emulated with collision avoidance sensor, and acoustic
detectors imitate the sonar in bats. Similar to the ability of our body
to monitor the temperature and keep it within healthy acceptable limits,
our homes, offices, and other enclosed areas have environment control
that allow us to operate at comfortable temperature levels. One of the
recent studies related to applications in aerospace include the
development of an artificial fly unmanned aircraft system with combined
hearing and vision for navigation to inaccessible locations. This is an
on-going research at the University of Maryland that is funded by the US
Air Force Office of Scientific Research (AFOSR)
\[<http://www.af.mil/news/story.asp?id=123125017>\]. In this study, the
capability of a pair of mechanically-coupled ears that are separated by
only 500 microns is being investigated while seeking to incorporate
advances in microelectronics and other system-on-a-chip capabilities.
This study is focused on the understanding, modeling and emulation of
the ability of flies to combine hearing and vision at micro-scale levels
as means of rapid flying and response.

[Artificial Intelligence (AI)]{.underline}: Controlling the operation of
systems in automatic way can be limited if a simple software with known
answers to any of the possibilities is used. Increasingly, systems are
being made "smart' using artificial intelligence where the control
algorithms are emulating nature \[Musallam et al., 2004; Mussa-Ivaldi,
2000\]. The field of AI is providing important tools for making
automatic and robotic mechanisms with capabilities such as knowledge
capture, representation and reasoning, reasoning under uncertainty,
planning, vision, face and feature tracking, language processing,
mapping and navigation, natural language processing, and machine
learning \[Bar-Cohen and Breazeal, 2003; Kurzweil, 1999; Luger, 2001\].
Generally, AI is a branch of computer science that studies the
computational requirements for such tasks as perception, reasoning, and
learning, to allow the development of systems that perform these
capabilities \[Russell and Norvig, 2003\]. Through improvement of the
understanding of human cognition \[Hecht-Nielsen, 2005\] scientists are
able to understand the requirements for intelligence in general, and
develop artifacts such as intelligent devices, autonomous agents, and
systems that cooperate with humans to enhance their abilities. AI
researchers are using models that are inspired by the computational
capability of the brain and explaining them in terms of higher-level
psychological constructs such as plans and goals.

# 4.5 Robotics as beneficiary of biomimetic technologies

Creating robots that mimic the shape and performance of biological
creatures has always been a highly desirable engineering objective
\[Bar-Cohen and Breazeal, 2003; Bar-Cohen and Hanson, 2009\]. The term
robot refers to a biomimetic machine with humanlike features and
functions that consists of electro-mechanical mechanisms. Also, it
suggests a machine that is capable of manipulating objects and sensing
its environment as well as equipped with a certain degree of
intelligence. Searching the Internet for the word robot brings numerous
links related to research and development projects that are involved
with robots. Manipulator arms that are fixed to a single position and
perform such tasks as painting and assembly are part of many production
lines including the manufacturing of cars. Rovers that have locomotion
with wheels or legs are already being made autonomous and are able to
perform quite sophisticated tasks. These include the Mars Rovers that
have operating since 2003 on Mars in terrains that are unknown and they
are capable of avoiding obstacles while conducting various tasks in
support of the exploration of this planet.

The entertainment and toy industries have been greatly benefited from
advancement in this technology. Toys that emulate the appearance and
movement of such creatures as frogs, fish, dogs and even babies are now
part of many stores. The higher end robots and toys are becoming
increasingly sophisticated, allowing them to walk and even converse with
humans as well as appear converse with human using a limited vocabulary
at the level of hundreds of words. Some of the robots can be operated
autonomously or can be remotely reprogrammed to change the
characteristic behavior. An example of a robot that expresses and reacts
to human expressions facially and verbally is the Kismet that was
developed at MIT \[Bar-Cohen and Breazeal, 2003; Breazeal, 2004\]. As
this technology evolves it is becoming more likely that in the future,
humanlike robots may be part of our daily life operating at our homes
and offices and doing work that currently is done by humans. Beside the
benefits of this technology there is a need for awareness of the
potential risks that these robots may pose due to errors or even
malicious intents.

Industry is increasingly benefited from advancement in robotics and
automation that are biologically inspired \[Bar-Cohen, 2000; Bar-Cohen
and Breazeal, 2003\]. Crawlers with the equivalence of legs as well as
various manipulation devices are increasingly being used to perform a
variety of nondestructive evaluation (NDE) tasks. At JPL, a
multifunctional automated crawling system (MACS) was developed to allow
rapid scanning of aircraft structures in field conditions (Figure 15).
The MACS consists of two legs for the mobility on structures with one of
the legs designed also to rotate. This crawler performs scanning by
"walking" on aircraft fuselages while adhering to the surface via
suction cups and is capable walk upside down on such structures. The
mobility on structures is critically dependent on the capability of the
legs to have controlled adherence and alternative forms that were
reported include the use of magnetic wheels and electrostatic field.
Using magnetic wheels, the author and his coinvestigator \[Bar-Cohen and
Joffe, 1997\] conceived a rover that can operate on ships and submarines
using magnetic wheels. Another legged robot is the JPL's STAR that has 4
legs and can perform multiple functions (Figure 5), including grabbing
objects as well as climbing rocks with the aid of the ultrasonic/sonic
anchor on each of the legs \[Bar-Cohen, 1999; Bar-Cohen and Sherrit,
2003; and Badescu et al. 2004\]. This anchor provides the ability to
"hang-on" rocks via mechanism that requires a relatively low axial force
to drill into the rocks as well as extract the bit in a reverse action.
The JPL's legged robots are developed for potential operation in future
planetary mission, where a Lemur class robot will be able to
autonomously negotiate its way through unknown terrain that is filled
with obstacles (Figure 16).

Figure 15: MACS crawling on a wall using suction cups on two simulated
legs.

Figure 16: JPL's Lemur, 6-legged robots, in a staged operation (Courtesy
of Brett Kennedy, JPL/NASA)

# 4.6 Summary -- the challenges and potential development

The evolution of nature over billions of years led to highly effective
and reasonably power efficient biological mechanisms, which are
appropriate for the intended tasks and that last \[Petr, 1996\]. The
ongoing evolution eliminates failed solutions and often leads to the
extinction of specific species that do not sustain the changing
conditions. As it evolves, nature archived its solutions in the genes of
creatures that make up the terrestrial life around us. Imitating
nature's mechanisms offers enormous potentials for the improvement of
our life and the tools we use. With the capability of our today's
science and technology we are significantly more capable of employing,
extracting, copying and adapting nature's inventions.

Nature offers a model for us as humans in our efforts to address our
needs as well as a source for inspiring many human-made devices,
processes and mechanisms. By studying nature from the angle of seeking
ideas for biologically inspired technologies many applications can
result including stronger fiber, multifunctional materials, improved
drugs, superior robots, and many others. Preventing the loss of Nature's
solutions that managed to survive at least till we understand them well
is an important aspect of biomimetics where we need to assure that
species are not extinct since they may harbor inventions that we have
not appreciated yet. We can learn manufacturing techniques from animals
and plants such as the use of sunlight and simple production of
compounds with no prolusion, biodegradable fibers, ceramics, plastics,
and various chemicals. One can envision the emergence of extremely
strong fibers that are woven as the spider does, and ceramics that are
shatterproof emulating the pearl or possibly seashells. Besides
providing models, nature can serve as a guide to determine the
appropriateness of our innovations in terms of durability, performance,
and compatibility.

The inspiration of nature on aerospace is expected to continue growing
and to enable technology improvements with impacts on every aspect of
our lives. Miniature flying devices that are as small as a fly or less
with speeds and performance of the dragon fly are still a challenge to
mimic. However, some of the inspired future capabilities may be
considered science-fiction in today's terms, but as we improve our
understanding of nature and develop better capabilities this may become
a reality that is closer than we think.

# 4.7 Acknowledgement

Some of the research reported in this Chapter was conducted at the Jet
Propulsion Laboratory (JPL), California Institute of Technology, under a
contract with National Aeronautics and Space Administration (NASA).

**Copyright 2008 California Institute of Technology. Government
sponsorship acknowledged**

**This comment will be removed once a Copyright Transfer form is
submitted to the publisher.**

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