Manufacturing of the motor mount of the uBox, an Intelligent Pillbox
by
Jessica Le6n
SUBMITTED TO THE DEPARTMENT OF MECHANICAL ENGINEERING
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
BACHELOR OF SCIENCE IN MECHANICAL ENGINEERING
AT THE
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
JUNE 2008
@2008 Jessica Le6n All rights reserved
The author hereby grants to MIT permission to reproduce and to
distribute publicly paper and electronic copies of this thesis document in whole or in part in any
medium now known or hereafter created
A uthor ..........................................
...............
DepartmeAnt of Mechanical Engineering
/
Certified by .......................
.......................
May 9 t" 2008
........ ...............
Amy Smith
Department of Mechanical lngineering Senior Lecturer
Thesis Supervisor
Certified by..
John H. Lienhard V
Professor of Mechanical Engineering
Chairman, Undergraduate Thesis Committee
MASSCHUSTTSINSIrUT
MASSACHUSETTS INSTITUTE]
OF TECHNOLOGY
AUG 14 2008
AiRCHVES
-
LIBRARIES
Manufacturing rigs and glues for motor assembly of the uBox, an intelligent pillbox
By
Jessica Leon
Submitted to the Department of Mechanical Engineering
on May 9 h 2008 in partial fulfillment of the
requirements for the Degree of Bachelors of Science in
Mechanical Engineering
ABSTRACT
The uBox has been developed to be a solution to the medication adherence problems for a
multitude of applications. The box offers a way to collect and formulate patient and volunteer
adherence data for use in the field while offering a critical locking feature for the pills inside the
box. The uBox is currently transitioning to production on the order of hundreds. A rig was
designed to reduce error in the assembly of the locking mechanism. This includes a device to
mount the motor accurately and repeatably which is critical to the function of the uBox. In
addition, the strengths of different glues for the mounting of the motor were analyzed and
optimal glue was determined.
Thesis Supervisor: Amy Smith
Title: Senior Lecturer
Table of Contents
1 Introduction ........................................................................................
.................................................
1.1 The Tuberculosis Problem ......................................................................... .............................
6
8
1.2 Innovators in H ealth Solution: uBox ................................................................ ............................. 9
1.3 The current Design and Possible improvem ents ..................................... .................................. 11
2 M otor Placem ent C urrent D esign ...................................................................................................
14
2.1 M etal Jig ............................................................................................................................................ 15
2.1.1 M etal Jig D esign
............................................
16
2.2 Clam p M echanism .............................................................................................................................
2.2.1 Clam p D esign
16
..............................................
16
2.3 G lue ................................................................................................................................................... 18
2.3.1 Forces on Motor ......................................................................................................................... 19
2.3.2 Research ..................................................................................................................................... 20
2.3.3 Testing M ethod .....................................................................................
................................ 20
2.3.3 Results ................................................................................................................................................... 22
3 Future W ork .............
4 Conclusion .......................
..........................................................................................................
.........................................................
5 References .................................................................................................................................
...
23
.............
24
. . 25
Figures
Figure 1: The uBox, a smart pillbox that collect patient adherence information through internal
data collection ...................................................
9
Figure 2: Exploded View of Pillbox showing the mechanical components that come together .. 11
Figure 3: The motor and worm gear interface. When mounted at an angle, jamming occurs...... 12
Figure 4: Motor and electronics integration into the uBox for locking mechanism. In the physical
uBox the motor is glued to the round electronics board which is shown floating above in this
figure .
.....................................................................
13
Figure 5: Forces on the motor when driving the rack forwards and backwards for the locking
mechanism of the intelligent pillbox. [1] ........................................................ ....................... 14
Figure 6: Top and side views of the electronics board that interfaces with the motor. The notable
features are the electronic components that protrude from the board and must be accounted for
when making a motor mount jig. ......................................................................... ................... 14
Figure 7: Jig for mounting the motor onto the electronics board of the uBox.......................... 15
Figure 8: Jig with appropriate cutouts for the electronic components .................................... 15
Figure 9: Jig showing the spring pins used as an alignment mechanism with the electronics board
and the interface between the two ................................................................................................. 16
Figure 10: Clamping mechanism - the portion that holds the electronics board in place while
gluing. ......................................................
17
Figure 11: Clamp mechanism for holding the motors down with 6 boards and jigs loaded ........ 17
Figure 12: Clamping mechanism as it closes, putting pressure on the motor as the glue dries. This
ensures proper adhesion. ............................................................................................................... 18
Figure 13: Clamping Shear forces on the motor as the rack gear is moved. ............................ 19
Figure 14: Forces on the worm gear when the worm gear is driving. The gears used in the uBox
are similar thus experience similar forces .........................................................................
20
Figure 15: Tensile force on the glue is perpendicular to the glued surfaces while shear force is
the force parallel to the glued surfaces. Glue is generally stronger in the shear direction. .......... 20
Figure 16: Tensile testing of the glue which holds the motor onto the electronics board. ........... 21
Figure 17: The testing rig for shear stress on the glue interface between the motor and electronics
board for the uBox. ................... .............................................................................................. 21
Figure 18: The distribution of adhesives scaled based on strength and work time. The optimal
glues reside in the optimal work time zone and are high strength .....................................
. 23
Tables
Table 1: Adhesive properties of glues that are available for the motor mount of the uBox. The properties
listed are important to the strength and durability of the adhesive joint. The highlighted areas are those
that werer measured in the laboratory. ....................................................... ........................................... 22
1 Introduction
Tuberculosis(TB) is an airborne disease that has become a worldwide problem. Despite the fact
that it is a treatable, curable disease, it is estimated that 1.5 million people died from TB in 2006.
If treated early and fully, patients become non-infectious and cured. If not treated, a TB infected
person infects 10-15 people each year due to its infectious nature. The primary problem with TB
treatment is adhering to the extensive and time consuming drug regimen which last for months
and causes severe side effects.
Through the World Health Organization, the heart of stopping TB is a program called
DOTS(Directly Observed Treatment, Short-course) which focuses on maintaining a constant
flow of drugs with personal monitoring. Patients following the DOTS program are visited by a
volunteer who brings their medication and validates that the patient took the pills. Running these
DOTS programs in geographically dispersed developing rural communities is a difficult
logistical challenge. It is important to know the patient's adherence record(whether or not they
tool their pills) and patient-volunteer interactions, however this is difficult in areas with low
literacy and depends on the motivation of the DOTS volunteer. Furthermore, data is gathered
manually, making it error-prone and costly to collect and distribute.
A solution to this problem is the uBox: a cheap, rugged pillbox that is left with the patient and
which electronically records times of dosages and DOT worker visits. This little pillbox locks 2
weeks worth of pills inside and unlocks when it is time to take the pills. This locking prevents
overdose and ensures that the patient receives the pills at the right time. Its internal electronics
detect when a pill is dispensed and when a volunteer with the patient(inserts a dongle into the
box). Then the data is then stored in the box's internal memory. Collecting and formulating this
data offers timely and targeted intervention to adherence problems, thus improving the overall
adherence and promoting better patient care. It also offers opportunity for a rigorous evaluation
of new incentive schemes and other program innovations. The uBox requires virtually no
training and does not rely on infrastructure or user literacy. A prototype uBox is currently in the
assembly and testing phase. It will cost about $2 per patient per trial (one-tenth the cost of the
leading market solution). We are working closely with the Prajnopaya Foundation and their TB
clinic in Bihar, India, where we will be conducting a 200 patient trial in the fall of 2008
This increase in manufacturing volume reveals a need to improve the manufacturing process. To
make this pillbox robust and reliable, critical features must be modified and improved. One such
aspect of the uBox is the locking feature. The current locking assembly is inefficient and offers
huge possibilities for error in jamming. To improve the assembly of the locking mechanism, the
motor must be accurately placed and clamped down while the adhesive dries.
1.1 The Tuberculosis Problem
Each year, 8-10 million people are estimated to contract tuberculosis (TB) and 1.5 million die
from the deadly disease and the problem is growing each year by 0.6 percent. In most cases TB
can be completely cured with a combination of antibiotics, and most governments offer these
drugs free to financially needy citizens. Therefore, the main challenge is drug adherence:
ensuring that patients follow a tight regimen of drugs throughout a 6-8 month treatment period.
The reasons that patients do not take their TB medication are complex and many; the treatment is
long, the drugs may have intense side effects, health worker interactions may not be frequent
enough, and many other personal reasons.
A successful and much-replicated approach to TB treatment is the DOTS strategy, in which a
health worker supervises every dose to ensure adherence. The regimen includes a standard short
course of drugs which lasts 6 months for new patients and 8 for those who have restarted
treatment. A DOTS worker delivers the drugs to the patient's home and supervises as the patient
takes their medication. This method is promoted worldwide by the World Health Organization.
Regular worker interaction is critical in ensuring compliance and cannot be substituted by
technology, however the DOTS program can be augmented by having reliable, up to date
knowledge of what is happening in the field. Even with motivated workers, information is
gathered manually, limiting its scope, making it error-prone and hard to efficiently collect and
distribute. Some workers travel for miles to get to their patients and lack the literacy to take
down important patient information.
1.2 Innovators in Health Solution: uBox
A reliable, robust means of measuring performance allows program directors to evaluate
treatment program innovations and to incentivize the best DOTS workers. Intimate knowledge of
the communities and personal interaction are indispensible, however these aspects can be
augmented with a way to systematically monitor progress and achieve consistently high drug
adherence rates. The uBox initiative gathers reliable patient, volunteer and operational data using
universally applicable, low-cost and easy-to-use techniques. The box stores information on when
a pill was dispensed and when the health worker interacted with the patient. This data, along with
data collected from other
The Innovators in Health (IIH) mission is to gather and process real-time patient and operational
information to dramatically improve healthcare delivery and judge its efficacy. The IIH has
developed the uBox seen in Figure 1 along with many other devices to track drug adherence,
patient and health worker interaction, and patient health.
Figure I: The uBox, a smart pillbox that collect patient adherence information through internal data
collection
The uBox is a palm-sized, intelligent pill dispenser, which reminds patients to take their
medication, records when a patient has taken a dose, and locks itself to prevent double-dosing.
This allows reliably tracking medication. The pillbox senses when patients take doses and logs
that information in the internal memory. In addition, DOTS worker interaction is monitored
through a key that interfaces with the uBox.
The data is taken off of the box through the key hole and can be loaded onto a cell phone or
PDA. The information is then analyzed through the software that has been developed especially
for the uBox. This software organizes the data for easy analysis based on gender, region, DOTS
worker, and many other factors.
IIH has been working with the Prajnopaya foundation in the area of Bihar India. This region was
selected because of the dense and poor population, and high level of TB incidence. Trials of 200
uBoxes are being planned for Fall of 2008. This offers a large need for the manufacturing of the
uBox to improve because the uBox will be with workers in the field with little technical help
from IIH. This requires that the components are assembled accurately and with high quality.
1.3 The current design and possible improvements
The ubox is composed of a circular base that holds the electronics, a pill holding compartment
that rotates around the base and ratchets with the base as seen in Figure 2, a cover, a door for pill
compartment and a top cover that locks everything in place.
Top cover with key-hole
interface and led lights
Gripper for
easy turning
Main cover to
hold inpills
Rotating pill
compartments -
Bottom base that houses
the rack and aligns the
electronics board
Motor and gear mechanism that
interfaces with holes inthe rotating
pill compartment to lock the pillbox
Figure 2: Exploded View of Pillbox showing the mechanical components that come together
Locking and releasing is achieved through interfacing between the base and pill compartment.
As seen in Figure 2, the motor is housed in the base of the pillbox and drives a rack. This rack
locks the uBox when it slides into an indent in the rotating pill compartment.
The current design of the uBox involves many injection molded parts, electrical components and
mechanical gears that form the working pillbox. Previously, the uBox was manufactured on a
very small scale and several manufacturing problems arose: the motor mount was not
accurate,
and the glue failed during tests.
The motor was previously mounted by hand and was very difficult to align. The motor
must be
placed accurately in the degrees of freedom, namely the x, y, and theta directions to prevent
jamming. Placement by hand proved to be nearly impossible and resulted in unnecessary forces
on the motor when the gears jammed. These build up of forces may have contributed to the glue
failure.
x
t4y
Worm Gear
Worm Gear
Rack Gear
Correct Placement
Rack Gear
Incorrect Placement - results in
Jamming motors and increased forces
Figure 3: The motor and wiorm gear interface. WN'hen mounted at an angle, jamming occurs.
The glue that was used was a five minute epoxy. This glue failed after running in the pillbox
during testing. Better glue is needed to ensure that the motor stays attached to the electronics
board and to maintina the functionality of the locking mechanism.
2 Motor Placement Current Design
The locking feature is critical to the success of the pillbox in both developing world and US
markets. Our community partner in Bihar India has confirmed the need for locking as have
others in Russia and the US.
The locking mechanism is compact and fits within the inside compartment of the uBox. This
offers little opportunity for mechanical joining techniques and the motor's small size limits
mechanical joining possibilities. Therefore, chemical adhesives were chosen to attach the motor
to the electronics board as seen in Figure 4. The motor glues to the electronics board then
interfaces with the gears through a press fit. The resulting worm gear and pinion combination
drives the locking of the device.
Electronics that are aligned
into the base via the
/alignment holes.
Motor, worm gear and rack. The motor is
glued to the bottom of the electronics board
and the rack is housed inthe base
Figure 4: Motor and electronics integration into the uBox for locking mechanism. In the physical uBox the
motor is glued to the round electronics board which is shown floating above in this figure.
The motor must be placed in a very specific orientation to avoid jamming. The best way to
achieve this is to use a jig that aligns itself with the board and holds the motor in place while
gluing. To ensure that the glue dries evenly between the motor and the board, it is important to
put pressure on the motors as they dry.
The motor experiences forces when locking and unlocking the uBox. The forces acting on the
motor put pressure on the adhesive joint and has led to failure in some previous prototypes. This
can be eliminated by determining a stronger adhesive for the uBox and treating the surfaces
properly before gluing.
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Figure 5: Forces on the motor when driving the rack forwards and backwards for the locking mechanism of
the intelligent pillbox. II
2.1 Metal Jig
The motor must be oriented in the x, y and theta directions for proper function of the box. The
most critical direction is the theta direction because it is most likely to cause a jamming in the
gears. Therefore the jig must interface with the board to ensure alignment. This design must be
intuitive to use and repeatable because of the high volume of boards that will be assembled.
The boards come from the contract manufacturer with electrical components soldered on. The jig
must not interfere with the pre-existing electronics on the board. It should accommodate the
structures while providing enough support for the jig and motor to sit flat on the board.
Alignment Tab
Electronic components
Mounting
holes
A1
Top View
Side View
Figure 6: Top and side views of the electronics board that interfaces with the motor. The notable features are
the
electronic components that protrude from the board and must be accounted for when making a motor mount
jig.
2.1.1 Metal Jig Design
The jig, as shown in Figure 6, provides support for the motor while gluing and drying by
aligning the motor in the proper place and avoiding contact with the glue itself. It was successful
in mounting the motor accurately and repeatedly. The reasoning for the design is discussed
below.
Glue channel
--
Motor channel
Cutouts for
electronics
.
Alignment pegs
Motor alignment
angle
Figure 7: ,Jig for mounting the motor onto the electronics board of the uBox
Cut-outs shown in Figure 7 were machined to avoid damaging the electrical components and
ensure that the jig sits flush with the board itself. This allows the jig to be secured tightly for
better motor placement.
Figure 8: Jig with appropriate cutouts for the electronic components
15
The jig was machined on a CNC milling machine to achieve better accuracy in making the parts.
CNC machining offers repeatability and helps eliminate variability in the parts. This ensures that
the jigs are all the same so that the motors are mounted in a repeatable manner as well.
Alignment between the electronics board and the jig was achieved be using the mounting holes
in the electronics board. The jig was machined with matching holes. Spring pins of the proper
diameter (5/64 in) were pressed into the jig holes and acted as pegs which fit into the holes on
the board, effectively aligning the two.
Glue channel
Mount sits flush
with electronics
board
Alignment pegs
made from spring
pins
Figure 9: Jig showing the spring pins used as an alignment mechanism with the electronics board and the interface
between the two
The motor channel was given a tolerance of .005in to account for possible variation in the motors
while maintaining a tight enough fit to keep the angle correct. A glue channel was placed around
the motor channel to avoid contact between the glue and the jig. Rounded inside edges were
designed for easier machining and cleaning of the jig.
2.2 Clamp Mechanism
The clamping mechanism's function is to put pressure on the motor while the glue dries and to
hold the board in place so it is easier to insert the metal jig. The clamp houses six assemblies and
keeps the components organized. The pressure on the motors will ensure that the glue dries
evenly.
2.2.1 Clamp Design
The clamp holds the board in place using the alignment tab as seen in Figure 9. This helps to
align the electronics board before placing the jig in the clamp device. It makes the jig placement
easier for a more intuitive manufacturing process.
After aligning the electronics board
Alignment tab fit
into cutout to
align the board in
the clamp
Figure 10: Clamping mechanism - the portion that holds the electronics board in place while gluing.
The jig is then placed onto the board(2). The spring pin posts fit through holes in the clamp base
for precise alignment within the clamp structure.
Figure 11: Clamp mechanism for holding the motors down with 6 boards and jigs loaded
The top cover is then rotated down onto the motors and clamped down(3).
Top cover that
clamps down
Rubber that
compresses motor
while drying
Metal Jig
Electronics board
Figure 12: Clamping mechanism as it closes, putting pressure on the motor as the glue dries. This ensures proper adhesion.
Pressure is put on the motors for better glue adhesion, rubber nubs are used as the pressure points
because they will deform to allow for variability in boards and motors.
2.3 Glue
Because the motor is glued onto the electronics board, an optimal adhesive is needed to ensure
that the motor stays secure during the life of the pillbox. The adhesive will be used at medium
volumes for manufacturing, thus need to have certain characteristics for easy handling and
application. The characteristics that are important in this analysis are the: materials the glue
adheres to, handling time, set time, cure time, mixing requirements, set temperature, and tensile
strength.
The glue must have the correct chemical composition to adhere to the fibreglass board and the
steel body of the motor. If the glue is not properly chosen in this regard, failure could result by
the motor detaching from the board.
The handling time is the amount of time that the glue will be workable before becoming tacky
and difficult to handle. This is very important to the manufacturing of the uBoxes because the
assemblers must be able to work with the adhesive for long enough to coat several motors at
once. If the adhesive has a very short handling time, fewer motors can be glued at once, causing
the manufacturing process to slow down.
The set time is the amount of time that it takes for the glue to harden enough to work with the
motor/board combinations. It is when the glue has hardened but has not reached full strength.
This characteristic is important because the motors will have to sit in the motor mount and clamp
until the adhesive has finished setting. This means with a shorter set time, the amount of time the
motors have to sit in the clamp goes down, and assemblies can be made faster. This also
decreases the number ofjigs and clamps that are needed.
The cure time is the time it takes for the adhesive to reach full strength. In the case of the uBox,
it is the time it takes before the box can be assembled after gluing. Shortening this time will
shorten the gap between gluing and assembling the internal parts of the locking mechanism.
Mixing requirements refers to the need for the adhesive to be mixed or activated. Some
adhesives require a chemical reaction to occur before applying to the intended surfaces. Epoxies,
for example have two components that are mixed before applying. This adds another step to the
gluing process and is not desirable, however it may be necessary for stronger adhesives.
Set temperature is the temperature that the adhesive will be effective after reaching full strength.
The environment that the uBox will be in varies based on location but can reach over 130
degrees Fahrenheit. It is important to ensure that the adhesive can survive in the environment.
The tensile and shear strength of the adhesive refers to the strength of the adhesive normal to the
surfaces in the tensile case, and parallel to the adhesive surfaces in the shear case. The forces felt
by the motor are mainly in the shear as seen by Figure 13, therefore it is the most important
direction to analyze.
2.3.1 Forces on the motor
Glue
Reactive Forces
Efrom
Rack
Worm Gear
Rack Gear
S
Movement
Orom Motor
Figure 13: Clamping Shear forces on the motor as the rack gear is moved.
The forces on the motor are caused by the interface between the worm gear and the rack. As the
motor turns, the worm gear pushes on the rack, moving it in the horizontal plane, therefore
putting stress on the horizontal plane of the worm gear and motor.
2.3.2 Research
Several glues were analyzed for the characteristics described above. After obtaining these glues,
they were tested in tensile and shear loading. The motor experiences forces seen in Figure 14.
r-OW
Figure 14: Forces on the worm gear when the worm gear is driving. The gears used in the uBox are similar
thus experience
similar forces.
The tensile force is the upwards force on the glue and it refers to the force perpendicular to the
surface that is glued. The shear force is perpendicular to the surface glued, therefore in this case
it is pushing the motor forward. These forces can be seen in Figure 15.
Glue
L
Motor surface
Tensile force:
perpendicular to
glued surface
Figure 15: Tensile force on the glue is perpendicular to the glued surfaces while shear force is the
force parallel to the glued
surfaces. Glue is generally stronger in the shear direction.
2.3.3 Testing Method
The motors were glued onto a fibreglass board using the rig and clamp mechanism after
being
scored and washed. The motors were tested in the tensile direction by connecting
a force sensor
to the shaft and applying upwards force perpendicular to the adhered surfaces
as shown in Figure
11.
Force Sensor
-.
Electronics board with
motor glued on
FIigure 16: Tensile testing of the glue which holds the motor onto the electronics board.
The motor was stressed in the tensile direction by using a rig setup that converted tensile,
pulling force to compression force on the back of the motor to simulate the motor being pulled
by the rack during movement as seen in Figure 12.
Force o
Figure 17: The testing rig for shear stress on the glue interface between the motor and electronics board
for the uBox.
2.3.4 Results
Table I: Adhesive properties of glues that are available for the motor mount of the uBox. The properties listed are
important to the strength and durability of the adhesive joint. The tensile and shear strengths were measured in the
laboratory and are shown in the light grey columns. The dark grey rows represent the best adhesives based on strength.
Time
Name
2 Ton epoxy
work (min)
30
locktite
Amazing goop Auto
set (min)
Temp
cure (hr)
Tensile (kN/m^2)
Shear (kN/m^2)
Min (F)
Max (F)
200
Mix?
120
8
241
785
-60
M/A
1N
1on
724
_-
nAA
V
5
5
24
481
835
-22
175
Y
N/A
20
72
266
962
-65
300
Y
10
24
72
570
1038
-40
150
N
5 miniti lnnvXv
Urethane 50
Streneth
Y
The light grey columns represent the results of the strength testing in the tensile and shear
directions. The most critical direction of the applied force is the shear direction because that is
the direction that the motor will experience the most since it is constrained in the tensile
direction. The force meter that was used has a force range up to 11 kg and the best adhesives
were stronger than that force. The Plastic Welder Epoxy, Urethane 85, and Super Glue were all
very high in shear force. In order to pick the best adhesive, it is important to look at the other
factors that affect ease of use and strength through time.
The Work time is very important in manufacturing. The super glue is at a disadvantage because
the work time is so short so the glue hardens before the motor and board can be properly set. The
assemblers are likely to not have enough time to place all of the motors before the glue dries.
The Plastic Welder Epoxy and Urethane 85 are both better because they have about a 5 minute
work time which is in the optimal work time zone shown in Figure 18.
Optimal Work Time
Zone
LSuper Glue
2 Ton Epoxy
Amazin
onnn
Locktite
Strength
Urethane 50
5 min Epoxy
Work Time
Figure 18: The distribution of adhesives scaled based on strength and work time. The optimal glues reside in the optimal
work time zone and are high strength.
Temperature and set time are both important to determining the best glue because the uBox will
be present in harsh conditions. Bihar, India experiences high temperatures up to 115 F, and all of
the adhesives would survive in this temperature. Set time is also important because it determines
how long the motors must be in the clamp before they can be removed to reach full strength. The
motors only need to be compressed in the clamp while the glue cures, once the glue has set and
has hardened, the alignment and pressure is no longer needed and another set of motors can use
the clamp. Since the Plastic Welder Epoxy, Urethane 85, and Super Glue all have a low set time,
they are all viable options.
One important factor in determining the best glue is smell. The Plastic Welder Epoxy has a very
pungent odor that is nearly unbearable, therefore the resulting winner is the Urethane 85 because
of its high strength, work time, and set time.
3 Future work
The motor mounting mechanism was approved by critical IIH engineering staff, however
requires additional testing. The jig succeeds in aligning with the electronics boards and hold the
motor in place while gluing. What is needed is a way to test the location of the motor placement
and its effect on the gear interfaces as well as the chosen glue. The optimal way to test the motor
placement and glue strength is to rapidly iterate locking and unlocking uBoxes. The effectiveness
of the jig and clamping mechanism can be determined by comparing motors assembled with the
jig against those assembled by hand.
Proposed method:
-Assemble full uBoxes from motors mounted with and without the jig/clamp mechanism
-Run a program that locks and unlocks uBoxes in quick succession
-Check ubox after 20 lock/unlock cycles to determine when failure occurred
-Compare results between motors mounted with and without jig and clamp
This test will determine the effectiveness of using the alignment mechanisms and determine
where improvements can be made to the jig design.
4 Conclusion
The jig and clamp mechanisms will greatly improve the ease of manufacturing the uBox for
medium scale production. The clamp mechanism allows 6 motors to be glued and clamped at
once, effectively speeding up the gluing process. The clamp also organizes the motor mount
components. The jig easily attaches to the electronics boards and aligns the motor without much
effort from the assembler. This decreases the manufacturing time because the assembler no
longer needs to constantly adjust the motor placement. The jig also increases the reliability and
life span of the uBox. The motor is aligned therefore jamming is avoided and reduces the forces
that pull apart the glue. Glue failure is also avoided because optimal glue has been found. The jig
and clamp mechanisms allow faster, more efficient, and more accurate manufacturing for the
uBox. This will allow the box to be more reliable in the field and have a positive impact on the
global tuberculosis problem.
5 References
[1] Hamrock, Bernard J. FundamentalsofMachine Elements. McGraw Hill 2004
[2] World Health Organization. Tuberculosis Factsheet 2008. WHO April 2008