abstract of snake robotics

8/9/2019 Abstract of Snake Robotics

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K.S.RANGASAMY COLLEGE OF TECHNOLOGY

TIRUCHENGODE 637209

SNAKE ROBOTS

APPLICATIONS AND

DESIGN

DESIGNED BY

TARUN SINGH

K.

MANIKANDAN

FINAL Yr B.E.,

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controlled, to avoid

the problem of

artificial intelligence

and sensing. They

needed to be simple

to drive. For the

applications that we

are interested in, the

main challenge in

designing these

robots deals with

putting actuated

joints in a tight

volume where we

minimize the length

of the stages and

their cross sectional

areas. For the next

design iteration, wewill omit the

extension degree of

freedom in favor of

having a shorter bay

length. Therefore,

the main concept of

our design, as well as

many others, is to

stack two degree-of-

freedom joints on top

of each other,

forming a serpentine

robot.

Key word: snake

robot, confinedspace, degrees of

freedom,

Serpenti

ne robot

Why snake

robots?

Biological

snakes occupy a

wide variety of

ecological niches,

ranging from arid

desert to tropical jungle as well as

swimming in rivers

and oceans.

Abandoning limbs

and developing

elongated spines has

proved an effective

survival strategy,

allowing snakes to

hunt underground in

confined tunnels,

above ground in

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grassy fields and up

in the tree-tops, even

falling in a controlled

glide from one tree

to the next. By

attempting to build

robots that emulate

and perhaps match

the capabilities of

their biological

counterparts, it is

possible that we will

create useful tools

capable of carrying

sensors, taking

samples, and making

physical changes in a

wide variety of

environments. Therobot designs

evolved from one

generation to the

next, incorporating

lessons learned from

previous prototypes.

Require

ments for the

designs included that

they were to be

untethered, which

meant they had to

carry their own

computers and

batteries. They were

to be radio-

controlled, to avoid

the problem of

artificial intelligence

and sensing. They

needed to be simple

to drive. The large

number of segments

had to be controlled

using one or two

joysticks. The long

term goal is to

enable exploration in

dangerous

environments and toaid in search and

rescue. A hoped-for

side effect is to

encourage people to

look at snakes in a

new way,

appreciating what

they have to teach

us about navigating

and traversing the

world.

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Snake robots

have many

applications, but are

hard to control. A

person cannot simply

operate each joint of

a snake individually

because there are

too many. These

robots require a

motion planning

algorithm. Motion

planning for snake

robots is difficult

because the robots

have many internal

degrees of freedom

that have to be

coordinated toachieve purposeful

motion. In motion

planning jargon, this

means the snake

robots exist in large

dimensional

configuration spaces.

Our work will make it

possible for the

robots to operate in

several different

modes from fully

autonomous to

human-guided. The

robot will be able to

optimize its own path

based on a range of

cost functions from

power consumption

to safety or even

stealth.

Mechanism and

Design of snakerobots:

Snake robots

are a new type of

robots, known also as

serpentine robots. As

the name suggests,these robots possess

multiple actuated

joints thus multiple

degrees of freedom.

This gives them

superior ability to

flex, reach, and

approach a huge

volume in its

workspace with

infinite number of

configurations. This

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redundancy in

configurations gives

them the technical

name: hyper

redundant robots.

Here we develop new

snake robot designs.

Ideally, the future

snake design will

consist of three

degree of freedom

stages --- roll, pitch,

and extension.

Sometimes stages

are called bays. For

the applications that

we are interested in,

the main challenge in

designing theserobots deals with

putting actuated

joints in a tight

volume where we

minimize the length

of the stages and

their cross sectional

areas

For the next

design iteration, we

will omit the

extension degree of

freedom in favor of

having a shorter bay

length. Therefore,

the main concept of

our design, as well as

many others, is to

stack two degree-of-freedom joints on top

of each other,

forming a serpentine

robot.

There are three

main schools of

designs for these

kinds of robots:

actuated universal

joint, angular swivel

joints and angular

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bevel joint. The

simplest design that

first comes to mind is

stacking simple

revolute joints as

close as possible to

each other and this

led to the actuated

universal joint

design. However

these kinds of

designs are bulky

and not appropriate

of lots of serpentine

robot applications.

Another kind of bulky

two DOF joints are

pneumatic snakes.

The second design

that evolved was the

angular swivel joints,which is present in

the JPL Serpentine

Robot. These are

much more compact

two DOF joints. The

design is simple:

starting with a

sphere, then slicing

the sphere into two

parts such that the

slice plane is

transverse to the

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south-north pole axis

of the sphere. Now

rotate one half

spheres with respect

to the other

orthogonal to the

sphere at the poles

and coordinating the

motors that rotate

those hemispheres

leads to a two DOF

joint and notice the

motion of the poles.

Putting the snake

bays

APPLICATIONS

Robotics

develops snake-

arm robots for

confined

spaces.

Historically

automation has

focused on tasks in

unconfined spaces.

We are all familiar

with robots on

production lines

where there is plenty

of room in which to

operate.

What is a

confined

space?

Confined spaces

exist by design (e.g.aircraft engine), by

failure (e.g. collapsed

building) or naturally

(e.g. human body).

It is important to

realize that confined

spaces only exist

where there is areason why the

confined space

shouldn't or can't be

converted into an

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level of confined

spaces legislation,

which raises the cost

of manual access,

especially in dirty

and dangerous

environments.

Snake-arm robots

can add value as well

as saving money. For

instance snake-arm

robots may enable

you to design and

build in a different

way - e.g.

automating low

access assembly and

designing for

automatedmaintenance that

avoids disassembly.

Snake-armrobots foraircraftassembly

Compared to

the automotive

industry, the

aerospace industry

has been slow to

introduce industrial

robotics onto its

assembly lines.

Recently, however,

there has been a

general move

towards automation

in order to increase

throughput and

standardise

processes. The slow

introduction of

industrial robots into

the aerospace

industry is largely

due to the need for

high accuracy over

large structures. Forexample, holes have

to be drilled within

large structures with

both high absolute

and relative accuracy

relative to other

holes and features of

the aircraft

assembly.

Airbus has

been researching low

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cost, highly flexible

automation for

several years.

However, tasks

within rib bays and

other low access

areas found

throughout aircraft

structures have

remained practically

inaccessible to

automation.

Manoeuvring an

industrial robot

through a small

opening becomes an

eye of the needle

problem: it becomes

practically impossibleto use a conventional

robot-arm to pass

through an access

hole, for example,

and conduct work

within a wing box.

Operating within a

rib bay requires

some of the

capabilities of

industrial robots, e.g.

the ability to place

tools precisely, but

other capabilities

must be added to

operate within

confined spaces. In

particular it is

necessary to have a

robot arm that does

not have prominent

elbow joints. Snake-

arm robots, having

continuous curvature

along their length,

are ideal for these

applications.

Aerospace

Applications

Robotics isworking with Airbus

UK and KUKA to

develop aerospace

robots to deliver end

effectors packages

capable of

inspection, drilling,sealing and swaging.

A snake-arm robot

can be considered as

an additional tool

that the larger

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industrial robot can

deliver or as an

extension to the

industrial robot. The

image on the right

shows the industrial

robot providing the

linear movement

required for path-

following with the

snake-arm robot

attached as a

forearm at the

industrial robots

wrist.

The snake-arm is

also equipped with a

wrist and interface to

attach different tools

for tasks such as

swaging, sealing and

inspection inside the

rib bay.

Tools and

applications

The purpose of

a snake-arm is to

introduce tools or

sensors into a

confined space. In

order to maximize

the benefit of the

snake-arms path-

following capability,

the diameter of theend effectors

envelope must be

equal to or less than

the diameter of the

snake-arm. The

length of the end

effectors must be

minimized, ideally to

the diameter of the

snake-arm or at least

to less than 1.5x the

diameter. In addition

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to these

considerations,

further restrictions

were placed on the

-arm robots.

Three

interchangeable end

effectors were

designed by Robotics

for the demonstrator:

1 An inspection

tool containing

several

cameras with

ones

2 various

function

3 A swage toolto swage a

rivet and direct

the removed

section into a

collection area

1 A sealant tool

incorporating astandard sized

sealant

cartridge and

nozzle, with

cameras to

allow

automatic

orientation of

the tool piece

to the seam.

A Snake Robot

Search-And-

Rescue

Mission-

scope for

future

applications

This scenario is

purely imaginary and

is presented to help

provide a goal for

future developmentsrather than stating

current capabilities.

Following a major

earthquake the

ground floors having

collapsed remain

standing but

unstable, threatening

to fall at the next

aftershock. Willing

rescuers stand ready

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to climb and dig, but

the question remains

of whether the risk of

injury to them is

worth the chance of

finding someone

buried under the

rubble. Fortunately, a

new generation of

search-and-rescue

snake robots is now

available to answer

that question. Pulling

out a 2-meter long

tube from under the

stretcher in the

paramedic

ambulance, the

operator opens oneend and powers up

the system. Operator

removes a remote

control unit which

has a video screen

built into it, fed by

the camera from the

head of the robot,

with a graphical

overlay allowing a

range of optional

behaviors to be

activated.

There are also

two joysticks and a

variety of other

buttons and knobs

for controllingsubsidiary

parameters of the

system. The would-

be rescuers carry the

tube as close as

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possible to the

wreckage, and slide

the snake robot out

of the end of it. A

thin composite cable

goes from the inside

of the tube to the tail

of the snake,

supplying power and

carrying data in both

directions. The

operator activates

the snake's

locomotion system

and moves it

forwards. It

automatically adapts

to the uneven ground

and rises up oversmall obstacles while

maneuvering around

the larger ones.

Pausing every few

feet to listen for

signs of survivors,

the snake robot's

head relays binaural

stereo sound back to

the operator. Hearing

no cries for help, the

snake is directed

towards a 20-cm

wide gap where one

house has collapsed

and is leaning

against another.

Approaching the

aperture, the snake

transitions to

rectilinear motion,

and uses infrared

distance measuring

devices and flex-

sensor whiskers to

center it between the

walls. As it moves

further inside, the

operator switches to

the infrared-sensitive

camera andilluminates the scene

with high-power

LEDs.

As the snake

progresses, it sweeps

the area up ahead

with a pyroelectric

device to look for

body heat. Its

underbody (ventral)

scales pull the robot

along the ground like

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a small conveyor

belt, even pushing it

through the tangled

heaps of cables left

by the collapsed

building. Then it

reaches a region of

shattered plaster and

broken rubble, which

provides insufficient

grip for forward

locomotion. The

tether is also pulling

on the snake robot's

tail, caught as it is on

previous

obstructions. At the

system's on-screen

suggestion, theoperator switches the

snake robot to

internal power and

detaches the tip of

the tail by remote

control. This now

becomes a base

station

communicating

wirelessly with the

snake robot and

relaying information

back to the operator.

Small scales on

the skin of the snake

robot grip the walls

and allow it to push

forwards by changing

the amplitude of its

coils in one region

while gripping with

another. Once

through this difficult

area the snake

comes to a region of

the original floor of

the house. The snake

swishes its head from

side to side to sweepthe area clean of

rubble. Using a

downward-sensing

ultrasonic device in

the chin of the robot,

the operator

determines that it is

possible to make a

hole leading directly

to the basement of

the building. The

snake robot it

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instructed to detach,

from under its head,

a small shaped-

explosive charge,

which it leaves on

the floorboards and

slithers back slightly

before detonating

the charge and

making a 10-cm hole

in the floor. Curling

its head downwards

through the opening

it pushes forwards by

a meter or so and

then uses its neck to

point its head in a

variety of directions

looking for survivors. There is a peak

detected by the

pyroelectric sensor,

and the snake

freezes, going silent.

The

microphones pick up

the faint sounds of

breathing and the

infrared camera

indicates a blob in

approximately the

direction from where

the sounds

originated. The

operator pinpoints on

a map where the

survivor is most

likely to be found.

The location is shown

in relation to a

reconstructed 3-D

model of the path

taken by the snake

robot, along with the

surfaces it sensed.

Other rescuers are

given the go-ahead

to carefully approach

the building as the

operator talks to thesurvivor over a

loudspeaker carried

by the snake robot,

letting him know that

help is one its way

and trying to

discover the extent

of his injuries.

CONCLUSION

In this paper

the fundamental

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needs and design of

snake robots were

dealt with. Since the

snake like robot has

multiple degrees of

freedom, it can be

used for several

applications. The

applications of snake

robots in aircraft

industry for assembly

and accurate drilling

operations were also

dealt elaborately.

The application

search and rescue

robot for various

hazardous areas has

been discussed indetail. Since the

snake like robots can

also move through

the confined spaces

its applications are

still extended to

nuclear and intricate

places. This paper

will give an overview

of serpentine robot in

various applications

and hazardous

environments

References

www.google.com

www.snake

robots.com

www.findfast.com

www.altavista.com

In

dustrial Robotics

by Robert

GrooverIn

dustrial Robotics

by Deb

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abstract of snake robotics

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