2. literature review for wheel chair

8/16/2019 2. Literature Review for wheel chair

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Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.

After receiving our project brief it was clear that the group needed to assess

whether the access to niversity College !ondon"s #C!$ premise was a problem for

wheel chair users. %t was clear that accessibility for wheel chair users was a problem.

&roup one set out to tackle the challenge of building a robot that would scale the

portico steps at the front of C!. #'igure 2.($ %n doing so it was necessary to design a

robot not only capable of climbing stairs) but one where the design would be easily

implemented to other devices such as a wheel chair. *he second step in the project

was to review the available stair climbing robotic designs.

2.1 THE LITERATURE REVIEW

2.1.1 Continuing the trend of the WORM [2.1]

*his project was geared around e+tending a previous fourth year origami

project under ,r. 'ry"s supervision. *he student who based his project on yet a

previous origami self-folding robot #also supervised by ,r. 'ry and conducted by

Figure 2.1. A google sketch up model of the UCL portico steps. (author:

unknown) (Search: UCL in google sketch up)


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third year students at C!$ set out to design and build a stair climbing robot which

folds out on each step at a time.

*he robot #nicknamed the /R0: andering /rigami Robotic 0achine$ was

controlled by eight servos and its motion resembled a progressive forward rolling set

of modules. 1ach module has the ability to rotate about its connection point. *his

allows it to rotate above and over the proceeding module. *his is illustrated in 'igure

2.2 a$.

Figure 2.2 a) The WOR i! actio! as it asce!ds the first step. (author: A. Morel)


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0orel is one of the few people who have attempted to use this modular design

to tackle the stair situation. A team in Switerland had attempted the same thing with

their robot 3 4et another 0odular Robot #4a0oR$. *he 5enormous6 advantage to

using modules according to 0orel is that it enables the creator to more accurately

replicate natural behaviour through robotic movement 3 5like snake-robots) several

legged-robots and any arbitrary structure6. 72.28

*he modules ascend stairs by first rolling towards the first step. *he /R0

has an advantage of being able to proceed in any linear direction. *he last lower

module is then able to rotate over the one preceding it) and the system of modules on

top rise above the front top module. At this point the modules are above the step

height) and the new front top most module is able to rotate mount the first step.

*he new front top most module is now able to rotate forward and also land on

the step. At the same time the system of wheels behind rotate upwards in order to hold

a rigid rectangular structure. #*he front module now is resting on the second step

rising.$ At this stage the /R0 is on the first step 3 *9 on 'igure 2.2 b$.

Figure 2.2 ") The WORs asce!t from the first step. (author: A. Morel)


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Rotating the new front top module forward the /R0 can begin the ascent of

the ne+t step and so on. *he descent is not e+plored in 0orel"s report) but the reversed

motion of the modules could easily be used to transport the /R0 down the steps.

At first) group one members were very eager to pursue the /R0 design. %t

was suggested by the 0Sci student that the original eight servos could be increased to

twelve. Although this was a good starting point) the group felt that the /R0 design

led itself to the motion and efficiency of caterpillar tracks. 'urthermore) it was hard to

see how any collection of lone modules could support the weight of a wheel chair and

user. *he group was also unsure it the /R0 could effectively tackle spiral stairs.

Conclusion: e decided to e+plore other possibilities.

2.2 Stir !"i#$ing ro$ot%

2.2.1 The To&Chir [2.']

Created by a team in 'rance the *opChair is an electric wheel chair with an

incorporated stair climbing mechanism. *he chair has four wheels used for flat

terrain) and for all normal purposes it performs the function of a normal motorised

wheel chair.


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hen the chair approaches some steps) the owner can switch to 5step mode6.

*his directs the power to the tracks. #*he chair must approach the steps backwards$

*he front wheels then retract placing the rubber tracks on the ground. *he owner

continues to drive backwards and as the chair approaches the first step the rear wheels

are raised into the wheelchair placing the track onto the first step. *his happens

automatically as the chair is fitted with %nfra-red detectors. *hrough the controls the

owner can begin the ascent.

/nce the chair detects the top step) the rear wheels and then the front wheels

are moved back down.

%n descending the steps the owner approaches the steps forwards and positions

the chair on the first step. e switches to 5step mode6 again. As before the front

wheels are moved up and the owner drives forward. hen the chair detects that the

centre of gravity has surpassed the first step nosing) the motion stops and the rear

wheels are retracted. As the chair detects the bottom of the steps) it moves down the

rear wheels. ;y choosing the 5road switch6 the front wheels reappear and the owner can drive away as normal.

Figure 2.#. The TopChair i! actio!. (http://pagesperso-orange.fr/topchair/DSC!"#.$%&)


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#*he following website illustrates the motion of the *opChair in more detail:

http:


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workers) to building surveyors to high school students who want to have a fun time at

their 5prom6 parties. 72.?8

*his is a credit to its design. %t is capable of tackling most terrains) rotating

9@= degrees at almost a ero radius) reaching the jar on the top shelf of a cupboard)

and most importantly climbing up and down stairs.

%n doing so the i;ot user re>uires the assistant of a trained person. *he ascent

occurs in three basic stages:

(. *he user approaches the step backwards. *hey then have to perform

several transitional functions on their electronic controller.

2. /nce ready) the user is then re>uired to grip the railing #so it is to your

disadvantage to be located towards the middle of the steps$ and gently

pull themselves forward. /nce the stair starts to move) the user must

then re-centre their gravity forwards to 5slow down6 the robot.

9. Repeat until you are at the top of the stairs.

*he descent occurs in the same way) with the user leaning backwards.

*he chair is able to climb stairs because of its four rotating wheels

#5clusters6$. 1ach set of clusters rotates about and above the a+es of the ne+t.

As each cluster lands on the ne+t step) the robot can leap frog up the flight of

stairs. *his motion is lengthy and re>uires great strength and balance from the user.

2.2.' The STAIRMA* [2.+]

*he S*A%R0A is designed by a &erman company called !ehner

!ifttechnik. *he company specialise in mobility for wheelchair users. *his device

unlike the others - attaches to regular wheel chairs and enables them to climb up and

down stairs. %t is an effective design.


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!ike the *opChair) motorised caterpillar tracks are used to transport the

wheelchair and user up and down stairs. *he tracks need to be fitted before the user

can tackle any stairs) and the tracks can be brought down or raised 3 allowing the user

to move to the stairs from the point of installation.

*he user approaches the stairs backwards and lowers the S*A%R0A. *he

wheelchair is then raised. *he advantage here over the *opChair) is that the tracks do

not need to be mounted directly onto the first step. *his is because the S*A%R0A is

designed with a tilted tracked front. *his means that the mechanism can approach the

first step) and through the caterpillar track grip on and pull the rest of its body forward

and upwards. *he tracks then continue up the stairs.

*he motion up the stairs is controlled by the user through a control at the front

of the mechanism #or behind the user as they are climbing up the stairs$. Although the

user and wheelchair enter the mechanism at an angle) during the ascent) the

wheelchair seat is returned to a horiontal position.

*he motion down the stairs is similar to the *opChair. *he tracks comfortably

take the user and wheelchair down the stair case. *his is partly due to the length of the

Figure 2.&. The 'TA(RA. A prouct of the Lehner Lifttechnik copan which specialisesin oilit for wheelchair users.( http://www.con0ar-etal.co/iages/staira1.0pg )

http://www.conjar-metal.com/images/stairmax.jpghttp://www.conjar-metal.com/images/stairmax.jpg


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mechanism. %t is over two hypotenuses of the steps. *his ensures that the journey up

and down the stairs is smooth and continuous.

2.2.) The %,M- [2.]

5A safe and effective stand alone climbing system which mounts to all

commercially available wheelchairs. S-0a+ isB. compact6. 72.8

%t may not be the bulkiest looking mechanism) but it is operationally practical.

*he s-0a+ has an effective load capacity of (@=kg. Spiral stair cases are not a

problem for this robot which producers #AA* 3 the stair climbing people$ call the

5ideal partner for life6.

AA* specialise in transport for people with physical disabilities. *his is

mainly focused at overcoming obstacles that wheelchair users may otherwise struggle

to tackle) such as stairs) but also includes motorising regular wheelchairs.

*he device appears at first to be a simple system) balanced on two rotating

wheels and two connected handles) e+tended to an assistant"s waist level with two

rods. /nce the system approaches a step however the cool stuff can beginD

*he system uses single climbing step technology to project the wheelchair and

user over the step. %t does this in three stages. 'irstly the device is attached to the

commercial wheelchair. *he assistant is then re>uired to approach the step backwards.

*hen) through electronic controls #included in the handle of the system$ the assistant

can release a robotic limb) which travels behind the set of wheels and lifts the

wheelchair above and over step onto the second step #e+tending and folding

mechanism$. 'inally) the limb retracts back into the device and the assistant can

proceed to the third step. *his process is repeated until the wheelchair is at the top of

the stairs.

%n descending the stairs) the assistant must approach the steps forwards) this

time with the centre of the set of wheels slightly beyond the nosing top step. *he


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e+tending limb will then land on the ne+t top step. A controlled descent can now occur

as the device lowers the wheelchair and folder up underneath it. *he assistant then

proceeds to the end of this step and the process repeats itself until the wheelchair is at

the bottom of the stairs.

Clever and original) even with such a simple designE its main selling point is 3

it"s compact and easy to use. *he s-ma+ does make the user dependent on others and it

may re>uire some strength. Also) it may take a bit of getting used to. %t is not >uite

clear at first how one should operate the system.

*he folding mechanism is very impressive) but perhaps not >uite the design

the group was hoping to investigate.

A %u##r/ of %tir !"i#$ing 0hee"!hir%

Stair

Climbing

heel Chair

Advantages !imitations Conclusion

*opChair

• 0odern.

•Re>uires noassistance.

• !ong lasting

performance.

• Already

attached to

wheelchair.

• Fery simple

and easy to

use.

•

Seat is kepthoriontalD

• Restricted to

a 99/

height• 1+pensive

• eavy

• 0ay be

difficult to

transport

• *oo

complicated

to replicate

• 0ay not be

suitableindoors or on

spiral stairs

*his is a good wheelchair) but in terms

of this project 3 it is too complicatedand e+pensive to be replicated. Also)

too much time is spent retracting and

returning the rear and front wheels.

#Got suitable for emergency

evacuation$

*he chair controls do not allow the

chair to manoeuvre spiral stairs and

this will be something the group hopes

to improve. *he design is simple

however) and the tracks are definitelyan element we will include to our own

design.

iBot

• 1asy to

transport.

• %nuires stair

rails and

moderate

strength or

assistance.

• 0ight

struggle with

spiral stairs.

• Complicated.

*his is a complicated design as

apposed to the *opChair. %t appears to

be stable) but the fact that the seat is

not horiontal means that most owners

tend to look uneasy on the seat.

#According to you-tube

demonstrations$

*he chair is not fool proof. %t re>uires both a stair railing and some strength

http://images.google.co.uk/imgres?imgurl=http://alumweb.mit.edu/upload/NZ/ibot_11676.jpg&imgrefurl=http://alumweb.mit.edu/clubs/nj/BrowseWeb.do%3Bjsessionid%3D363C8B6927AE0F0BC37188A40C114E34%3FwebSiteId%3DSI000519%26webPageId%3DP008%26eventId%3D1494&usg=__FTu6c-O5huJ6yk2Z4mZqqnJ4vGY=&h=400&w=299&sz=13&hl=en&start=6&um=1&tbnid=m0WT1PXGoCJcdM:&tbnh=124&tbnw=93&prev=/images%3Fq%3Dibot%26hl%3Den%26sa%3DN%26um%3D1


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intrusive. • 1+pensive

and heavy.

• Seat is tilted

during stair

operation.

• Restricted to

slope angle:

not stated) but

probably

higher than a

combination

of the two

wheel

diameters.

to force the motion up the steps or an

assistant #and some faith$.

%t is hard to see how this particular

design would be useful to our

objective.

S*A%R0A

• 1asy to

transport.• %ndoor use.

• Hractical.

• Got as

laborious to

manage as the

competition.

• Simple) easy

to use.

• Re>uires no

assistance or strength.

• Stable.

• 0otorised 3

nearly

effortless.

• Secure.

• Seat is

upright when

climbing

stairs.

• ,oes not need

to be mounted

onto the first

step.

• Got a part of

thewheelchair.

• 0ight not be

practical in an

emergency.

• 0a+imum

load capacity:

(9= Ig.

• 0ight

struggle with

spiral stairs.

• Corner stairs

need to be

very wide to

accommodate

the

wheelchair.

• /nly

applicable to

manually

driven

wheelchairs.

*he simplicity and strength of this

design makes it a useful device for &roup one to consider. %t is within the

scope of our project and group one

could aim to construct a similar

mechanism. *he mechanism) which

could be implemented to e+isting

wheelchairs #electric and manually

driven$) would re>uire a powerful

motor and a light frame.

*he frame would however need to

sustain the weight of a wheelchair anduser.

*he group can take a lot away from

this design. Spiral staircases will be

one of many elements we would hope

to incorporate. ;y avoiding any fancy

electronics group one can match the

practicality of the S*A%R0A.

Simple to build) use and understand.

#As apposed to the i;ot which comeswith a full manual and online

tutorials.$


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S 0A

• Could handle

spiral stair

casesuires

assistance and

patience.

• /nly

applicable to

manuallydriven

wheelchairs.

• Got suitable

for emergency

evacuations.

*he S 0a+ is simple) and stable) and

compact) and easy to use 3 but not

completely effective in overcoming the

step obstacle. 'or one) you would

re>uire an assistant at every staircase)

and it would help if you didn"t haveany where urgent to be.

/ne of the main selling points of the

i;ot


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circular support the robot can reach the highest step without risk of toppling over or

sliding backwards.

*he stair;/* is well constructed and its clever design can be attributed to its

creator and owner &unter endel #2==L$ who owns the rights to the robot design. *he

robot tackles steps in the following way:

*he system approaches the step and sensors detect the stairs. *he wheel then

rests drives to the first step and the brakes are applied. *he 5linear guide6 travels

forward beyond the first step and the brakes are released. *he wheel climbs up the

first step using the guide as a support. #%t travels up the guide$ hen the wheels are on

the first step) the brakes are applied again and the guide is drawn up into the wheel

pulling up the 5omniwheels6 as it does. *he wheel then proceeds to the ne+t step and

the process repeats itself until the wheels) guide and omniwheels are on the top step.

*he robot can then drive away.

/n taking the descent) the robot sensors detect the stairs once again. *he robot

then rotates (= degrees in order to tackle the stairs backwards. *he guide is first

lowered with the omniwheels onto the ne+t highest step #whilst the robot wheels are

stationary$. *he wheels then roll towards the step and roll down the guide onto the

second step. *his is basically the same process as before #when climbing up the

stairs$) but in a reverse order.

Again this method is repeated. /nce the wheels clear the last step) the robot

rotates back to its original position 3 with the wheels pointing in the direction of

travel #and away from the steps$ and rolls away.

Although it is a futuristic concept) % do not feel that this design is ideal for our

project. e do not re>uire any form of sensors and the group is against using wheels

to scale the portico steps. 'urthermore) it is hard to see how this design would support

a wheelchair and its user.

Conclusion: Got practical for our purposes. Could not be implemented to

wheelchairs easily and may be too e+pensive to build.


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2.2.+ The &eTri, Whee" 0hee"ed ro$ot [2.11]

*his design was an early favourite. %t was practical and effective as proven by

the fact that it is used in the movement of heavy goods items. *he rectangular shaped

robot has four sets of tri-wheels on each of its corners. *he robot"s driving motor and

servo motors are placed in the middle of the structure to ensure the robot"s stability

specially when climbing up stairs. 1ach tri-wheel has the ability to rotate around its

centre a+is. *his way the wheel is able to grip and mount the step sending the second

wheel forward over the step. *he third wheel then rotates over the second wheel

driving the robot forward. *his process is repeated for each step.

hen climbing down stairs) the robot seems to merely roll down.

,espite its simplicity and ease of operation this robot carries a flaw. %ts ability

to scale any set of stairs is limited to the sie of its wheels and wheel rotary system.

Figure 2.*. The peTri+ Wheel ,heeled ro"ot . ( http://www.outue.co/watch2

345*6o!67"89Afeature4relate )

http://www.youtube.com/watch?v=XzKo6KE2H5A&feature=relatedhttp://www.youtube.com/watch?v=XzKo6KE2H5A&feature=relatedhttp://www.youtube.com/watch?v=XzKo6KE2H5A&feature=relatedhttp://www.youtube.com/watch?v=XzKo6KE2H5A&feature=related


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*he robot has to be practically custom made for the stairs in >uestion and this is a

clear disadvantage.

Conclusion: A great idea) but with limited use. nfortunately even the portico

steps vary greatly in sie) so this design is not efficient enough for this project.

2.2. The three "egged ro$ot [2.12]

A group of final year university students in %ndia looks closely at human

mechanisms before constructing this ne+t robot. Although the robot failed to meet its

objectives it is nevertheless an interesting model to study. *he three legged robot

differs from other stair climbers as it uses legs to ascend and descend steps #as the

name suggests$. *he system relies heavily of a comple+ system of 5/n6 and 5/ff6

switches.

Synchronised motors work to move the back two legs simultaneously whilst

moving the front leg moves independently of the other two. At each command the

motor will hold the front leg in a set position whilst the other motor rotates the back

Figure 2.-. The three legged ro"ot. An inno3ati3e esign fro a tea of stuents in ;nia.

( http://www.con0ar-etal.co/iages/staira1.0pg )

;ack legs

http://www.conjar-metal.com/images/stairmax.jpghttp://www.conjar-metal.com/images/stairmax.jpg


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legs above and onto the ne+t step. *he motor then sets the two back wheels #now in

front$ in position and the motor controlling the front wheel is supposed to 5instantly6

move the front limb forward. *his leap frog system 3 identical to how humans would

ascend stairs 3 repeats.

*he movement down stairs would perhaps be the same with the robot now

facing the bottom of the steps. *his would work as the limbs do e+tend.

Conclusion: *he design is basic and its operation is fairly simple 3 one foot

over the other two 3 but the robot failed to climb any stairs and because of the team"s

decision to use 5robotic legs6 it renders the robot useless to our objective.

2.2.4 The Tn5 [2.1']

0odern tanks are some of the most durable machines in the world. *hey can

tackle some seriously inclined slopes with rough) uneven or soft surfaces. 1ven under

the most e+treme conditions) the tank is a favourite and acts as the first line of defence

for soldiers at the front line.

*anks come in all shapes and sies) but their use of tracks is common to all

types. A system of wheels is attached to either side of the tank with a metallic track

running over them. *his track is driven by two rear sprockets) which latch onto

periodic grooves in the tracks and rotate the track over the wheels. *his rotation

causes a friction with the wheels and the surface below 3 the tank begins to move

forward. ;y reversing the motion the tank moves backwards.


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*he added bonus here is that both tracks can move independently of the ne+t.

*his means that the tank can either turn slowly 3 one track side running slower than

the other 3 to either side) or rotate 9@= degrees 3 one track side reversed) one side

forward 3 with a small turning radius.

Several adoptions of this basic model have been created. /f them) some have

a non rigid structure with a front


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Figure 1./. A! adopted 0ersio! of the traditio!al ta!k desig!.


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Conclusion: *he simple design and rigid structure of this mechanism has been

used by many to tackle the stair problem. *he element of the tank which has been

adopted #even above for the stair climbing wheelchairs$ has been the tracks. *his is

within the scope of our project) but in order to succeed with this design we must be

sure to find the perfect track system.

2.2.3 The Shri#& [2.1)]

;uildable out of !ego) plastic) metal or anything you can find lying around the

shrimp is probably the most diverse of all the robots. %t has a simple design) whichmakes stair climbing an art.

*he shrimp tackles the step in the following way:

(. *he robot is designed to be able to scale steps without needing to be

5aware6 that it is doing so) and its wheels move forwards at all times.

2. *he front wheel scales the front step whilst the back wheel stabilises

the robot. %t can do this because the front arm is connected to the rest

of the structure through a pivot that can support the wheel up to an

angle of M= degrees from its original position.

9. /nce the front wheel is over the step) it begins to move forward) at this

point it effectively lifts the middle system of wheels up the stairs a pair

at a time #as illustrated above$ helped by any other wheels which are

also in contact with a surface.

*he middle system of wheels is connected through a fle+ible frame which can

fold and e+tend the front set of wheels whilst keeping the back set on the ground.

%GC!,1H%C*R1 Nhttp:


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*he shrimp is commercially available. *here are also various designs available

online for construction out of both !ego and 0eccanno.

Conclusion: *his mechanism could not easily be implemented to any wheel

chair as the robot constantly shifts its centre of gravity throughout the climb. *he

group also felt that there was little they could add themselves to the model) as both the

design and instructions for assembly were already fully comprehensive. %n search of a

more challenging project) this idea was rejected.

2.' The 6e%ign (!5ground

*he original group one tank design #'igure 2.(2.$ was modelled around

working tanks. A rhombus rigid structure would be bolted into shape with a driven top

back wheel and a caterpillar drive. %deas for caterpillar tracks ranged from bike chains

with a driving gear covered on the outside with carpet underlay to e+panding tough

foam. *he tank would be durable and since it was a borrowed design the group was

sure it would work. *he problem arose however when the decision had to be made

about choosing the correct motor.


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*his side view above shows the side profile of the robot with the front and rear

bars angled at L? degrees.

*he robust tank #now nicknamed: 5*he Rhino6$ would be too heavy for

any normal drill motor #as previously planned$. %n order to ensure the success of the

robot) the group had to purchase several geared motors. A series of gears can slow

down the motor revs) which stops the robot from skidding and increases the pulling

capabilities of the motor #its tor>ue$.

%n approaching the first step) it was decided that the rhino should have a

rhombus shape with L? degree rising front sides. *his way the caterpillar tracks

connected to the sides of the frame can latch onto the step and pull the system

forward. *o ensure that the robot continues climbing up the stairs it was initially

decided that the robot must be over three stair treads long) but eventually due to the

Motion of

robotMotion

of track

W

Motion

of track

Figure 2.12.. The rhi!os skeleto! frame. 'he sprocket an the front

wheel are ri3en as inicate the arrows (w). 'his ri3es the rest

of the track an the front an ack wheels. 'his sketch is not to scale

an illustrates a @ iensional sie 3iew of the root.(author:

aah Shai)

W

Skies


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varying sie of the portico steps) the robot was built to be over two average stair

hypotenuses.

*he rhino tracks would be driven by a set of rear motorised sprockets and

supported on each side by skies. #*his replaces the centre wheels in a regular tank$

*he rhino design was fully accepted by the group and ,r. 'ry had provided us

with eight wheels and some aluminium cornered bars. *he aluminium would make up

the skeleton of the rhino and si+ of the eight wheels #each with a @=mm diameter$

would be positioned on the robot as shown in 'igure 2.(9. *he decision was here

made to ignore the idea of a motorised sprocket. %nstead the bottom four wheels

would be driven by four motors #an effective four wheel drive$ and the tracks would

be placed first over the bottom two wheels on each side and a second turn would be

placed over the front two wheels and the inclined #non-driven$ wheels.

Adopting the rhino in this way meant that we could minimise the weight of the

robot. *he robot needed to be light and adaptable.

2. literature review for wheel chair

Documents