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TECHNICAL SEMINAR REPORT ON

SELF-REPLICATING ROBOTS

SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF BACHELOR OF TECHNOLOGY

IN

ELECTRONICS AND COMMUNICATION ENGINEERING

BY

GUTTULA. KRISHNA CHAITANYA 07M21A0424

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERINGLORDS INSTITUTE OF ENGINEERING AND TECHNOLOGY

(Approved by AICTE – New Delhi AND Affiliated to JNTU-Hyderabad)

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LORDS INSTITUTE OF ENGINEERING AND TECHNOLOGY (Approved by AICTE – New Delhi AND Affiliated to JNTU-Hyderabad)

Sy. No.32, Himayatsagar, HyderabadDEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

CERTIFICATE

In partial fulfillment f or the award of degree of bachelor of technology in ELECTRONICS AND COMMUNICATION ENGINEERING of JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY,HYDERABAD during the year 2007-2011. The TECHNICAL SEMINAR ON “SELF REPLICATING ROBOTS” has been approved as it satisfies the academic requirements in respect of technical seminar prescribed for bachelor of technology.

Asst. Prof. T. SRINIVAS RAO Prof. V. BHAGYA RAJU

(INTERNAL GUIDE) (HEAD OF THE DEPARTMENT)

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ACKNOWLEDGEMENT

I am obliged and grateful to our principal Mr. MASOD and head of the

department Mr. Prof. V.BHAGYA RAJ and Mr. T.SRINIVAS RAO, internal

guide for giving me guidance in completing this technical seminar successfully.

Finally I acknowledge with the gratitude the unflagging

support and patience of our PARENTS for their guidance and

encouragement during this dissertation work.

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ABSTRACT

Self reproduction is ultimate form of self repair. Self replication is generally

considered to be a machine that can build itself, and that they can build another

copy and so on. The self reproducing machines demonstrated here are essentially

modular robots, consisting of multiple identical actuated modules with

electromagnets to selectively weaken and strengthen connections.

The cubes are powered at the base and transfer data and power through their

faces. The control of machine is distributed among the modules executes a motion

schedule governed by time and contact events. The sides also have electromagnets

that enable them to selectively attach and detach from each other.

The modular robot can thus reconfigure itself. And in each block is a small

computer chip which is programmed with step-by-step instructions about what to

do. It is a small step towards developing robots that can repair and replicate

themselves in space or hazardous environments

INDEX

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INTRODUCTION 06

BACKGROUND AND HISTORY 07

CLASSIFICATIONS OF SELF REPLICATING ROBOT 08

CONSTRUCTION OF SR-ROBOT 11

DESIGN CONSIDERATIONS 13

SOFTWARE AND HARDWARE 14

WORKING PRINCIPAL 16

ADVANTAGES 23

DISADVANTAGES 24

APPLICATIONS 25

CONCLUSION 27

FUTURE SCOPE 29

BIBILOGRAPHY 30

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INTRODUCTION :

In this paper we review several prototypes of self-replicating robotic systems

that have been developed . In contrast to self-reconfiguration ,Self-replication is

the process of assembling a functional robot from passive components. The robot

that is assembled (the replica) is an exact copy of the robot doing the assembling.

Such systems have the potential to revolutionize the exploitation of resources in

outer space

Self-replication is an essential feature in the definition of living things. At

the core of biological self-replication lies the fact that nucleic acids (in particular

DNAs)can produce copies of themselves when the required chemical building

blocks and catalysts are present. This self-replication at the molecular level gives

rise to reproduction in the natural world on length scales ranging the ten orders of

magnitude . Not all of the machinery involved inbiological self-replication is fully

understood, and remains a subject of intensive

interest. Self-replication in non-biological contexts has been investigated as well,

butto a much lesser degree. These efforts have resulted in the field of “Artificial

Life”

This field is concerned with the sets of rules that, when in place, lead to

patterns that self-replicate. Such patterns are typically only geometric entities that

exist inside a computer. But they do provide an existence proof for non-biological

self-replication.

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BACKGROUND AND HISTORY :

The concept of artificial self-replicating systems was originated by John von

Neumann in the 1950's in his theory of automata. His theoretical concepts built on

those of Alan Turing's “universal computer” put forth in the 1930s. The main

difference was that instead of being able to read and write data, a self-replicating

system reads instructions and converts these into assembly commands that result in

the assembly of replicas of the original machine.

The vast majority of work in this area is in the form of non-physical self-

replicating automata (e.g., computer viruses, the ``game of life'' computer program,

etc.). The only physically realized concepts that have been explored related to true

self-replication certain to self-assembling systems. These interesting systems are

collections of passive elements that self-assemble under external agitation or

naturally occurring physical forces. There is no directed intention of a system to

deterministically assemble a copy of itself from passive components in these

physical systems, and the structures that are assembled are themselves passive.

Notable concept papers on self-replicating system for space applications were

put forth in the late 1970's and early 1980's. They proposed self-replicating

Factories that would weigh 100 tons each, but gave no concrete architecture,

system or prototype to demonstrate the feasibility of the concept. In contrast, we

discuss four self-replicating prototypes that have been developed at JHU by

the authors students in a course taught during the Spring of 2002.

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CLASSIFICATIONS OF SELF-REPLICATING ROBOTS

In this section self-replicating robots are categorized into two primary divisions

according to their behavior. The two divisions are denoted as ``directly

replicating’’and ``indirectly replicating,’’ respectively. The detailed principles of

these two divisions are described below. Figure 1 illustrates a diagram of how we

categorizeself-replicating robots.

Basically, a robot capable of producing an exact replica of itself in one

generation is what we call “directly replicating”. A robot capable of producing one

or more intermediate robots that are in turn capable of producing replicas of the

original are called “indirectly replicating”.

DIRECTLY REPLICATING ROBOTS

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We classify self-replicating robots in this division into four groups according to the

characteristics of their self-replication processes. The following are explanations of

each self-replicating robot group.

1 Fixture-Based Group

The self-replicating robots in this group depend on external fixtures in order to

complete the self-replication process. Some subsystems may require high precision

in positioning for assembling parts. Passive fixtures are able to assist in this

because of the shape constraints that they impose. In some other cases, to unit

push-pull fixtures are helpful as well. Regardless of the particular details, fixtures

serve as a substrate or catalyst to assist in the self-replication process, but are

themselves not actuated.

2 Operating-Subsystem-in-Process Group

In this group one or several subsystems of the replica can operate before the replica

itself is fully assembled. These subsystems are able to assist the original

selfreplicating

robot during the assembly of the replica. This assistance can come in

many forms. For instance, functioning subsystems can help in aligning,

manipulating, or transporting parts.

3 Single-Robot-Without-Fixture Group

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In this group only one robot is used to finish the self-replication process. Thus, the

robot in this group depends only on the available environment. Usually, the

complexity of the subsystems or the number of subsystems in the replica is very

lowfor this group. This is because without fixtures or multiply cooperating robots,

it isdifficult to position large numbers of subsystems with high precision.

4 Multi-Robot-Without-Fixture Group

In this group more than one robot works together in the self-replication process

without the assistance of fixtures. A major advantage is the reduction of the time

required for self replication. A disadvantage is that there may be interference

problems among robots.

There are several possible ways that a self-replicating robot can be categorized

in two or three groups mentioned above. The combination of two or three different

concepts can be incorporated in a potential design, such as a combining

operatingsubsystems-in-process with fixture-based robots. More categories are

likely to bedeveloped in the subsequent stages of our research in the area of self-

replicating robots.

2 INDIRECTLY REPLICATING ROBOTS

The primary characteristic of the robots in this division is that the original robot or

group of robots work together to build a robot-producing factory or some type of

intermediate robot which is able to produce replicas of the original robot.

However, the original robots lack the ability to directly assemble copies of

themselves.

CONSTRUCTION:

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A self replicating robot which has been developed recently contains a series of modular cubes called "molecubes" each containing identical machinery and the complete computer program for replication.

• Their robots are made up of a series of modular cubes -- called "molecubes" -- each containing identical machinery and the complete computer program for replication. The cubes have electromagnets on their faces that allow them to selectively attach to and detach from one another, and a complete robot consists of several cubes linked together. Each cube is divided in half along a long diagonal, which allows a robot composed of many cubes to bend, reconfigure and manipulate other cubes. For example, a

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tower of cubes can bend itself over at a right angle to pick up another cube.

• To begin replication, the stack of cubes bends over and sets its top cube on the table. Then it bends to one side or another to pick up a new cube and deposit it on top of the first. By repeating the process, one robot made up of a stack of cubes can create another just like itself. Since one robot cannot reach across another robot of the same height, the robot being built assists in completing its own construction.

• Although these experimental robots work only in the limited laboratory environment, Lipson suggests that the idea of making self-replicating robots out of self-contained modules could be used to build working robots that could self-repair by replacing defective modules. For example, robots sent to explore Mars could carry a supply of spare modules to use for repairing or rebuilding as needed, allowing for more flexible, versatile and robust missions. Self-replication and repair also could be crucial for robots working in environments where a human with a screwdriver couldn't survive.

• The cubes have electromagnets on their faces that allow them to selectively attach to and detach from one another, and a complete robot consists of several cubes linked together.

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DESIGN CONSIDERATION

The design phase of the replicators is very broad. A comprehensive study to date has identified 137 design dimensions grouped into a dozen separate categories, including:

(1) Replication Control,

(2) Replication Information,

(3) Replication Substrate,

(4) Replicator Structure,

(5) Passive Parts,

(6) Active Subunits,

(7) Replicator Energetic,

(8) Replicator Kinematics,

(9) Replication Process,

(10) Replicator Performance,

(11) Product Structure, and

(12) Resolvability.

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SOFTWARE AND HARDWARE

SOFTWARE

A quine is a computer program which produces a copy of its own source code as

its only output. The standard terms for these programs in the computability theory

and computer science literature are self-replicating programs, self-reproducing

programs, and self-copying programs.

A quine is a fixed point of an execution environment, when the execution

environment is viewed as a function. Quines are possible in any programming

language that has the ability to output any computable string, as a direct

consequence of Kleene's recursion theorem. For amusement, programmers

sometimes attempt to develop the shortest possible quine in any given

programming language.

The name "quine" is coined by Douglas Hofstadter in his popular science book

Gödel, Escher, Bach: An Eternal Golden Braid in the honor of philosopher Willard

Van Orman Quine (1908–2000), who made an extensive study of indirect self-

reference, and in particular for the following paradox-producing expression, known

as Quine's paradox:

"Yields falsehood when preceded by its quotation" yields falsehood when preceded

by its quotation.

The name has become popular between amateur enthusiasts and programming

hobbyists although it is not adopted by computer scientists.

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A quine takes no input. Allowing input would permit the source code to be fed to

the program via the keyboard, opening the source file of the program, and similar

mechanisms.

In some languages, an empty source file is a fixed point of the language, producing

no output. Such an empty program, submitted as "the world's smallest self

reproducing program", once won the "worst abuse of the rules" prize in the

Obfuscated C contest.

HARDWARE

The physical implementation of these algorithms has been done onthe Crystal

Robot. This robot use a novel actuation mechanism,scaling, which gives more

robust motion than the previous rotation based actuation systems.

A Crystal robot consisting of nine modules. The Crystal Robot has some of the

motive properties of muscles and can be closely packed in 3D space by attaching

units to each other. Each module is actuated by expansion and contraction.

By expanding and contracting the neighbors in a connected structure, an individual

module can be moved in general ways relative to the entire structure. Crystal atoms

never rotate relative to each other; their relative movement is actuated by sliding

via expansion/ contraction. This basic operation leads to new algorithms

for global self-reconfiguration planning. Each module has on-board

processing, sensing, communication, and power. We have implemented distributed

rule-based locomotion and self-replication on a 12 module Crystal robot.

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WORKING PRINCIPAL

Replication starts with, the stack of cubes bending over and sets its top

cube .Then it bends to one side or another to pick up a new cube and deposit

it on top of the first by repeating the process, one robot made up of a stack

of cubes can create another just like itself. Since one robot cannot reach

across another robot of the same height, the robot being built assists in

completing its own construction.

All robot modules begin in anundifferentiated state and divide into two

groups: left-facing andright-facing The module differentiation is done by

propagating of an integer variable called a signal through the system. As the

modules finish dividing (which they can detect by comparing signals in a

local neighborhood), they begin to locomote using the a distributed

locomotion approach based on local rules. Merge is similar.

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The prototype consisting of six subsystems:

Robot consists of six subsystems:

Module1(batteries,touch sensor and contact sensors),

Module2(state machine and contact sensors),

Module3(left motor and motor driver circuit),

Module4(right motor and barcode reader),

Module5(relay circuit) And

Module6(tracker sensor).

The state machine has six states and the robot has three distinctive behaviors for

each state: forward line-tracking, reversing and left turning while the timer is on.

These are decided by outputs from two different kinds of sensors, barcode reader

and contact sensors. The environment is built as shown in Fig.1. The

environmental structures are divided into two categories: (1)passive structures

and (2)active structures. The active structures store the information about

subsystems, therefore, the environment tells the robot where subsystems are and

what they are. On the other hand, passive structures affect the trajectories of the

robot but do not have further information.

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The Partially Structured Environment

Module 1 with the circuit diagram of the relay circuit and a metal detector, and a

part of a passive endeffector (a bar). Blue dots indicate the input terminals and red

dots denote the output terminals. Left Right

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(a) Before assembly (b)After assembly

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Module 2 with the circuit diagram of the line tracker sensors. Two pairs of IR

LED and photo diodes are used for line-tracking mechanism and a part of passive

end effectoris installed in M2.

Module 3 with the motor driving circuit diagram.ML is the left motor inside M3

and TS is a touch sensor installed in M5. Output ports described as Right motor are

connected to motors in M4.

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Module 4 includes a right wheel, a motor, and a bar code reader. The circuit

diagram of the bar code reader is shown. Every module shares the same power

source from M5.

Module 5 with the circuit diagram of 5-V power source and a LEGO touch sensor.

M5 contains four AA size batteries and three contact sensors installed at the

bottom. TS is the touch sensor attached on the frame.

Module 6 with the circuit diagram of the state machine. Three contact sensors

(same as in M5) are installed at the bottom, but omitted in the figure.

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The Partially Structured Environment

Structured environments can be divided into three categories:

a completely structured environment, a partially structured

environment, and an unstructured environment. We define a

completely structured environment to be one in which every

environmental structure is fixed at a precise location and no

change or permutation is allowed in these locations. A partially

structured environment is like a structured environment, but

with structures whose locations can be permuted and perturbed

by a small random error in pose. Thus, in a partially

structured environment, the robot can still perform selfreplication

when the location of one or more environmental structure is

switched with that of another structure.

An unstructured environment is an environment without any

structure resulting from initial human intervention.Our prototype

works in a partially structured environment.The environmental

structures include outer track, inner track, cross ways, six bar

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codes, six contact codes, backside wall, and metal line at the

station

ADVANTAGES:

Quality:

Robots have the capacity to dramatically improve product quality.

Applications are performed with precision and high repeatability

every time. This level of consistency can be hard to achieve any other

way.

Production:

With robots, throughput speeds increase, which directly impacts

production. Because robots have the ability to work at a constant

speed without pausing for breaks, sleep, vacations, they have the

potential to produce more than a human worker.

Safety:

Robots increase workplace safety. Workers are moved to supervisory

roles, so they no longer have to perform dangerous applications in

hazardous settings.

Savings:

Greater worker safety leads to financial savings. There are fewer

healthcare and insurance concerns for employers. Robots also offer

untiring performance which saves valuable time. Their movements are

always exact, so less material is wasted.

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DISADVANTAGES:

Expense:

The initial investment of robots is significant, especially when

business owners are limiting their purchases to new robotic

equipment. The cost of automation should be calculated in light of a

business' greater financial budget. Regular maintenance needs can

have a financial toll as well.

ROI:

Incorporating industrial robots does not guarantee results. Without

planning, companies can have difficulty achieving their goals.

Expertise:

Employees will require training in programming and interacting with

the new robotic equipment. This normally takestime and financial

output.

Safety:

Robots may protect workers from some hazards, but in the meantime,

their very presence can create other safety problems. These new

dangers must be taken into consideration.

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APPLICATIONS:

Self-replicating machines can have a wide range of applications as they simply

take labour effort out of an activity. Certain tasks such as terraforming a planet are

considered incredibly expensive and time-consuming. With self-replicating

machines, you only need to set the system up once and then forget about it for

many years. The system will take care of its own health.

It can be used for other space applications such as space travel, space

colonization, space exploration and space mining.

They are ideal as assembly machines. Some applications are

o Self-maintained fully autonomous factories

o Robot replicators used for cleaning and clearing up certain materials

from an environment

o Nano robots

Most of the research has occurred in a few areas:

Biology studies natural replication and replicators, and their interaction.

These can be an important guide to avoid design difficulties in self-

replicating machinery.

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Mimetic studies ideas and how they propagate in human culture. Memes

require only small amounts of material, and therefore have theoretical

similarities to viruses.

Nanotechnology or more precisely, Molecular engineering is concerned with

making machinery with nanometer-scale parts. Without self-replication,

capital and assembly costs of molecular machines become impossibly large.

Space resources- NASA has sponsored a number of design studies to

develop self-replicating mechanisms to mine space resources. Most of these

use computer-controlled machinery that copies itself.

Computer security: Many computer security problems are caused by self-

reproducing computer programs that infect computers.

Once it is possible to have self-replicators, the manufactured devices can be

improved by means of evolution. Some designs can have mutation before getting

replicated. Some designs can also be combined with cross-over to produce

something with characteristics of parent machines in a similar process to biological

evolution. Those machines that don’t perform well in the environment for the

particular task they were assigned to can be negatively scored. The lower their

scores, the lower their chances of producing offspring. Evolutionary replicators

eliminate the need for humans to put effort into improving the design of the

machines.

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CONCLUSION

Self-reproduction is the ultimate form of self-repair. We see that robotic

systems are becoming more complex, and in some cases like space exploration,

they need to sustain operation for long periods of time without human

assistance.

If you send a robot to Mars, for example, and it breaks, there is little you can

do. But if instead of sending a fixed robot you send a robot with a supply of

modules, then that robot may be able to self-repair and even make more and

possibly different robots if the mission needs change unexpectedly.

Revising and extending von Neumann’s early model of self replication

automata, we presented a simple framework for robotic replication consisting of

three sets of components. In addition, we characterized a system as being in one

of four categories: a PSRS, an ARS, a passive self-replicating system, or an

ASRS. The prototype presented in this article was viewed as an active self-

replicating system in that there is no external control or machinery other than

that by the initial functional robot. The replication process is composed of

assembling six subsystems in a partially structured environment, which holds

important information about the subsystems. A measure of the degree of

replication,Ds, as defined and applied to the prototype and other robotic

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replicating systems. Although the prototype presented in this article showed the

highest value ofDs among the systems being considered, it is still possible to

have a higher Ds by reducing the subsystem complexity and increasing the

number of parts, or having a uniform complexity distribution throughout

subsystems. Biological replication is a tremendously complicated process

That we are attempting to mimic in engineering systems. The current trend in

robotic self-replication is based on modular systems. To achieve sufficient

functionality of the robot and for a replication process to be meaningful, the

number of modules should be large and the module complexity should remain

as low as possible. The same degree of replication achieved in biological

systems may not be achievable by robotic systems. The main difference

between robotic systems and living organisms is that robots are invented and

used to satisfy human needs by performing specific tasks. In contrast, biological

organisms have no innate purpose other than survival and reproduction, and the

machinery to achieve these goals has been perfected over billions of years. One

of the goals we want to achieve in robotic replication is minimizing human

intervention and maximizing the functionality of the robot itself to perform

given tasks while also being able to reproduce.

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FUTURE SCOPE:

As the use of industrial automation has expanded over time, some factories have

begun to approach a semblance of self-sufficiency that is suggestive of self-

replicating machines. However, such factories are unlikely to achieve "full closure"

until the cost and flexibility of automated machinery comes close to that of human

labor and the manufacture of spare parts and other components locally becomes

more economical than transporting them from elsewhere. As Samuel Butler has

pointed out in Erewhon replication of partially closed universal machine tool

factories is already possible. Since safety is a primary goal of all legislative

consideration of regulation of such development, future development efforts may

be limited to systems which lack either control, matter, or energy closure. Fully-

capable machine replicators are most useful for developing resources in dangerous

environments which are not easily reached by existing transportation systems (such

as outer space).

An artificial replicator can be considered to be a form of artificial life. Depending

on its design, it might be subject to evolution over an extended period of time.

However, with robust error correction, and the possibility of external intervention,

the common science fiction scenario of robotic life run amok will remain

extremely unlikely for the foreseeable future.

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REFERENCES

[1] J.V. Neumann, A.W. Burks, ”Theory of Self-Reproducing Automata,”University of Illinois Press, 1962.

[2] M. Sipper, ”Fifty years of research on self-replication:An overview,”Artificial Life, 4(3), 1998, pp.237-257.

[3] L.S. Penrose,”Self-reproducing machines,” Scientific American, Vol.200,No.6, 1959, pp.105-114.

[4] S. Murata, H. Kurokawa and S. Kokaji, ”Self-assembling machine,” Proc.of the IEEE Intl. Conf. on Robotics and Automation, San Diego, CA,1994, pp.441-448.

[5] Z. Bulter, S. Murata and D. Rus, ”Distributed replication algorithm forself-reconfiguring modular robots,” Proc. of 6th Intl. Sym. on DistributedAutanomous Robotic Systems (DARS ’02), Fukuda, Japan, June 2002,pp.25-27.

[6] M. Yim, D. Duff, and K. Rufas, ”PolyBot: A modular reconfigurablerobot,” IEEE Intl. conf. on Robotics and Automation, vol.1, 2000, pp.514-520.

[7] www.arrickrobotics.com/robots.html

[8] www.robocommunity.com

[9] www.therobotlab.com

[10] www.roboticstrends.com/links_resources

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