Upload
shakil-malik
View
215
Download
0
Embed Size (px)
Citation preview
8/16/2019 2. Literature Review for wheel chair
1/22
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)
8/16/2019 2. Literature Review for wheel chair
2/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
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$.
Figure 2.2 a) The WOR i! actio! as it asce!ds the first step. (author: A. Morel)
8/16/2019 2. Literature Review for wheel chair
3/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
0orel is one of the few people who have attempted to use this modular design
to tackle the stair situation. A team in Switerland had attempted the same thing with
their robot 3 4et another 0odular Robot #4a0oR$. *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$.
Figure 2.2 ") The WORs asce!t from the first step. (author: A. Morel)
8/16/2019 2. Literature Review for wheel chair
4/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
Rotating the new front top module forward the /R0 can begin the ascent of
the ne+t step and so on. *he descent is not e+plored in 0orel"s report) but the reversed
motion of the modules could easily be used to transport the /R0 down the steps.
At first) group one members were very eager to pursue the /R0 design. %t
was suggested by the 0Sci student that the original eight servos could be increased to
twelve. Although this was a good starting point) the group felt that the /R0 design
led itself to the motion and efficiency of caterpillar tracks. 'urthermore) it was hard to
see how any collection of lone modules could support the weight of a wheel chair and
user. *he group was also unsure it the /R0 could effectively tackle spiral stairs.
Conclusion: e decided to e+plore other possibilities.
2.2 Stir !"i#$ing ro$ot%
2.2.1 The To&Chir [2.']
Created by a team in 'rance the *opChair is an electric wheel chair with an
incorporated stair climbing mechanism. *he chair has four wheels used for flat
terrain) and for all normal purposes it performs the function of a normal motorised
wheel chair.
8/16/2019 2. Literature Review for wheel chair
5/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
hen the chair approaches some steps) the owner can switch to 5step mode6.
*his directs the power to the tracks. #*he chair must approach the steps backwards$
*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!"#.$%&)
8/16/2019 2. Literature Review for wheel chair
6/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
#*he following website illustrates the motion of the *opChair in more detail:
http:
8/16/2019 2. Literature Review for wheel chair
7/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
workers) to building surveyors to high school students who want to have a fun time at
their 5prom6 parties. 72.?8
*his is a credit to its design. %t is capable of tackling most terrains) rotating
9@= degrees at almost a ero radius) reaching the jar on the top shelf of a cupboard)
and most importantly climbing up and down stairs.
%n doing so the i;ot user re>uires the assistant of a trained person. *he ascent
occurs in three basic stages:
(. *he user approaches the step backwards. *hey then have to perform
several transitional functions on their electronic controller.
2. /nce ready) the user is then re>uired to grip the railing #so it is to your
disadvantage to be located towards the middle of the steps$ 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$. 1ach set of clusters rotates about and above the a+es of the ne+t.
As each cluster lands on the ne+t step) the robot can leap frog up the flight of
stairs. *his motion is lengthy and re>uires great strength and balance from the user.
2.2.' The STAIRMA* [2.+]
*he S*A%R0A is designed by a &erman company called !ehner
!ifttechnik. *he company specialise in mobility for wheelchair users. *his device
unlike the others - attaches to regular wheel chairs and enables them to climb up and
down stairs. %t is an effective design.
8/16/2019 2. Literature Review for wheel chair
8/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
!ike the *opChair) motorised caterpillar tracks are used to transport the
wheelchair and user up and down stairs. *he tracks need to be fitted before the user
can tackle any stairs) and the tracks can be brought down or raised 3 allowing the user
to move to the stairs from the point of installation.
*he user approaches the stairs backwards and lowers the S*A%R0A. *he
wheelchair is then raised. *he advantage here over the *opChair) is that the tracks do
not need to be mounted directly onto the first step. *his is because the S*A%R0A is
designed with a tilted tracked front. *his means that the mechanism can approach the
first step) and through the caterpillar track grip on and pull the rest of its body forward
and upwards. *he tracks then continue up the stairs.
*he motion up the stairs is controlled by the user through a control at the front
of the mechanism #or behind the user as they are climbing up the stairs$. 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
8/16/2019 2. Literature Review for wheel chair
9/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
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$. 'inally) the limb retracts back into the device and the assistant can
proceed to the third step. *his process is repeated until the wheelchair is at the top of
the stairs.
%n descending the stairs) the assistant must approach the steps forwards) this
time with the centre of the set of wheels slightly beyond the nosing top step. *he
8/16/2019 2. Literature Review for wheel chair
10/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
e+tending limb will then land on the ne+t top step. A controlled descent can now occur
as the device lowers the wheelchair and folder up underneath it. *he assistant then
proceeds to the end of this step and the process repeats itself until the wheelchair is at
the bottom of the stairs.
Clever and original) even with such a simple designE its main selling point is 3
it"s compact and easy to use. *he s-ma+ does make the user dependent on others and it
may re>uire some strength. Also) it may take a bit of getting used to. %t is not >uite
clear at first how one should operate the system.
*he folding mechanism is very impressive) but perhaps not >uite the design
the group was hoping to investigate.
A %u##r/ of %tir !"i#$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
8/16/2019 2. Literature Review for wheel chair
11/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
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.$
8/16/2019 2. Literature Review for wheel chair
12/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
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
8/16/2019 2. Literature Review for wheel chair
13/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
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.
8/16/2019 2. Literature Review for wheel chair
14/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
2.2.+ The &eTri, Whee" 0hee"ed ro$ot [2.11]
*his design was an early favourite. %t was practical and effective as proven by
the fact that it is used in the movement of heavy goods items. *he rectangular shaped
robot has four sets of tri-wheels on each of its corners. *he robot"s driving motor and
servo motors are placed in the middle of the structure to ensure the robot"s stability
specially when climbing up stairs. 1ach tri-wheel has the ability to rotate around its
centre a+is. *his way the wheel is able to grip and mount the step sending the second
wheel forward over the step. *he third wheel then rotates over the second wheel
driving the robot forward. *his process is repeated for each step.
hen climbing down stairs) the robot seems to merely roll down.
,espite its simplicity and ease of operation this robot carries a flaw. %ts ability
to scale any set of stairs is limited to the sie of its wheels and wheel rotary system.
Figure 2.*. The peTri+ Wheel ,heeled ro"ot . ( http://www.outue.co/watch2
345*6o!67"89Afeature4relate )
http://www.youtube.com/watch?v=XzKo6KE2H5A&feature=relatedhttp://www.youtube.com/watch?v=XzKo6KE2H5A&feature=relatedhttp://www.youtube.com/watch?v=XzKo6KE2H5A&feature=relatedhttp://www.youtube.com/watch?v=XzKo6KE2H5A&feature=related
8/16/2019 2. Literature Review for wheel chair
15/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
*he robot has to be practically custom made for the stairs in >uestion and this is a
clear disadvantage.
Conclusion: A great idea) but with limited use. nfortunately even the portico
steps vary greatly in sie) so this design is not efficient enough for this project.
2.2. The three "egged ro$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$. *he system relies heavily of a comple+ system of 5/n6 and 5/ff6
switches.
Synchronised motors work to move the back two legs simultaneously whilst
moving the front leg moves independently of the other two. At each command the
motor will hold the front leg in a set position whilst the other motor rotates the back
Figure 2.-. The three legged ro"ot. An inno3ati3e esign fro a tea of stuents in ;nia.
( http://www.con0ar-etal.co/iages/staira1.0pg )
;ack legs
http://www.conjar-metal.com/images/stairmax.jpghttp://www.conjar-metal.com/images/stairmax.jpg
8/16/2019 2. Literature Review for wheel chair
16/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
legs above and onto the ne+t step. *he motor then sets the two back wheels #now in
front$ 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.
8/16/2019 2. Literature Review for wheel chair
17/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
*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
8/16/2019 2. Literature Review for wheel chair
18/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
Figure 1./. A! adopted 0ersio! of the traditio!al ta!k desig!.
8/16/2019 2. Literature Review for wheel chair
19/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
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:
8/16/2019 2. Literature Review for wheel chair
20/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
*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.
8/16/2019 2. Literature Review for wheel chair
21/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
*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
8/16/2019 2. Literature Review for wheel chair
22/22
Chapter 2 by: Rammah Shami. Contributing authors have been acknowledged.
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.