Baby Swing Electronics

Baby Swing Electronics
EE 492: Final Report
Group: Dec13-02
Group Members:
Adviser: Dr.Bigelow
Ahmed Alharmoodi
Client: Dr.Bigelow
Rashed Alfalasi
Mathew Seymour
Yezhou Fang
Table of Contents
1
Abstract
2
Problem Statement
3
General Solution
4
System Block Diagram
5
Design Standards
6
System Constraints
7
6.1
System technical constraints
6.2
System non-technical constraints
System Description & Components
7.1
7.2
Motion
7.1a
Electromagnet
7.1b
Push-pull Solenoid
7.1c
Brushless DC motor
System Control
Microcontroller
7.3
7.4
8
Final Design
PCB
9
Testing
Music
7.3a
SD card
7.3b
iPod dock
7.3c
Volume amplification and control
Power Circuit
Appendix
Appendix A: Project Plan
Summary
Problem Statement
General Solution
Intended Users
Operating Environment
Project Management
Work Breakdown Structure
Risks
Costs
Project Deliverables
Appendix B: System User Guide
Improvements & Suggestions
Warnings
Physical User Interface
Appendix C: Definitions
1
Abstract
We live in a time and environment in which creativity and reliability significantly
characterize our new technologies and innovations. Our senior design team has chosen the task
of redesigning the electronics of a baby swing, transforming it into a more reliable and creative
product. Reliable, whereby the product will last longer and be more practical in comparison to
other baby swings, creative by using new technologies that are more efficient and do the job
better. The whole redesigning process should cost less than $15.
The senior design team consisted of 2 Electrical Engineers, 1 Computer Engineer, and 1
Software Engineer. The Electrical Engineers were responsible for designing the system’s
required circuits, and testing. On the other hand, the computer and software engineer’s took
care of controlling the whole electronic system and getting the components interactive.
In the following document, the project team will outline the overall design of the
custom information status board. This document will walk you through every detail of the
product until reaching the final design.
2
Problem Statement
This project focused on redesigning the electronics of a baby swing. The problem with
the previous swing was that the motor was non-functional. Our group was assigned to replace
the motor with another component that is more reliable and adding more features to the
existing design.
The new design should be as follows; be able to download music from a memory stick so
that any song can be played as the baby swings. Be able to swing at a constant speed regardless
of the baby’s weight and remain rigid by changing to different speeds. Be able to operate
continuously for 15 hours a day 7 days a week for 2 years. Finally; the last requirement was to
be able to sell the swing for less than $15.
So we began by dividing the project into four main parts. The four parts were as follows;
power circuit, microcontroller, motion, and music. The power circuit powers up the whole
electronic system and insures each component gets the current it needs. The power system
was designed to supply 6V and 2A via an adapter to the whole system. Secondly is the
microcontroller, which was the center point to all other parts of the electronic system. It
controls the swing’s motion, music, and carousel. Thirdly; the brushed DC motor was replaced
with a brushless DC motor simply because it lasts longer and does the job much better. Finally;
in regards to music, we installed an iPod dock that plays any music the user wants.
3
General Solution
We divided our group tasks into two sections. One section will be taking care of the
programming part of the project. This section will be mainly programming the microcontroller
to do all sort of tasks such as controlling the motor’s speed and motion, and managing the
music. The other part of the group, which are all electrical engineers, will be responsible for the
motor and installing it in the swing, and designing circuits such as power circuit, volume
amplification circuit, voltage inverting circuit and other electrical related components.
In regards for fixing the baby swing, the only thing that needed to be fixed was the
brushed motor. The solution to this problem is to replace the motor with a better and a more
efficient solution, a brushless dc motor. Instead of letting the motor pull back and forth to get
the swing up to both sides, we will program it in a way that makes it pull the swing on one side
and then releases it. Once it pulls it, it then releases it for a certain number of periods and then
pulls it again, and again releases it and so forth and so on. This means that less power will be
used to get the swing moving while avoiding the potential danger of the motor overheating. In
addition, one does not need to worry about anything wearing out or not working as in the
brushed motor. In regards to the music, the iPod dock will be used to read the sound signals
and send it to the speakers.
4
System Block Diagram
Figure 1-System Block Diagram
5
Design Standards
Infant swings are stationary products with a frame and powered mechanism that
enables an infant to swing in a seated position. An infant swing is intended for use with infants
from birth until a child is able to sit up “unassisted”. The standards that will be required for the
design of this device are those that are currently being used in industry. The industry standards
specific to infant baby swings are those being produced by The U.S. Consumer Product Safety
Commission (CPSC). The CPSC focuses on safety standard to improve the safety of infant swings
to prevent injuries and deaths to children.
The U.S. Consumer Product Safety Commission safety standards that were related to
our designing process were as follows:




A stability test that prevents the swing from tipping
over
electrically-powered swings to be designed to
prevent battery leakage and overheating
dynamic and static load requirements to ensure that
the infant swing can handle specified loads without
breaking
recommend that the maximum amount of time for a
child in a baby swing in a single session is 30 minutes
In addition to the CPSC safety standards, this device complies with Part 15 of the FCC
Rules. In which the electronic system that we designed is subjected to the following two
conditions: (1) this device may not cause harmful interference (radio communications) and (2)
this device must accept any interference received, including interference that may cause
undesired operation. These limits are designed to ensure reasonable protection against harmful
interference in a residential installation.
6
System Constraints
The constraints defining the design of this product include both technical and non-technical,
and both are of great importance to the overall success of the project.
6.1
System technical constraints:

baby swing should be able to deliver enough torque to withstand a maximum
weight of 25 lbs

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

6.2
System non-technical constraints:



7
Be able to operate continuously for 15 hours a day 7 days a week for 2 years
Input power 10-15W
System input voltage at 6V exactly, no more nor less
Electronic system must be designed with all current standards
Be able to download music from memory stick so that any song can be played as
the baby swings
No overheating of any of the electrical components
Be able to charge external music device (iPod)
To ensure safety, maximum speed of the system of 1.5m/min and maximum
angle of swing of 20˚
System should be implemented on PCB
The whole electronic design should cost less than $15
Swing is reliable and safe
The system should allow the user to select the swing’s speed and the music
Easy to use
System Description & Components
Coming up with the final design was not that easy. A lot of components have been
replaced where we thought that they met the system design, but they didn’t. The first part that
we started researching on was in regards to motion. Getting the swing moving was our first
concern because that was the problem with the previous swing, and it is the most common
fault in baby swings. After the whole motion issue got solved, next thing that came on mind
was control. How would we be able to control every component of the system? The previous
design had no microcontroller; passive components have been used extensively, transmitter’s,
receivers and other circuital parts all for the sake of control. Microcontroller have made the job
much more efficient. After getting done with the ‘control’ part of the project, music came next
in line. The previous swing had the user restricted to pre-installed music in the board. The
group decided to use an iPod dock and a SD card reader gives the user to use any music he or
she wants. Also the music had volume issues, which we took care of, more will be explained in
the music part below. The last part in the design was the power circuit. The power circuit design
powers up the whole electronic system and insures each component gets the current it needs.
7.1
Motion
As said, getting the swing moving was the group’s first concern.
Getting the swing to move was not the only requirement, there were
also other things that we had to keep on mind while the swing was in
motion. We had to be sure that the swing was moving not too fast and
not too slow. So what we decided to do is to set the swing’s “free fall”
speed as the reference speed. From the reference speed we adjusted
other different speeds, both faster and slower. We also had to be sure
that the device responsible for moving the swing was not overheating
and does the job smoothly. Also while designing the whole system, we
had to keep track on cost. Many options have been disregarded due to
the cost.
The previous DC motor was a brushed motor (figure 2). It didn’t
work because the brushes wear out. The brush act as a bridge whereby
it connects the power source to the motor and without it, the motor
wouldn’t work. So we first started with the electromagnet, afterwards
the push-pull solenoid, and finally settling with the brushless dc motor.
Figure 2-previous DC motor
7.1a Electromagnet
So the first option that we had our mind was to use
an electromagnet. It is the most efficient and reliable way
to move an object from position a to b. Simply rap a
conductor coil ‘N’ times around an iron core (very good
permeability) and you’ll get a magnetic field with a strength
of:
Placing an iron core in the solenoid would also increase it
Figure 3- Solenoid
strength significantly.
The only issue that might arise with the electromagnet is it’s radio-frequency
interference. The disturbance may interrupt, obstruct, or otherwise degrade or limit the
effective performance of the circuit. These effects can range from a simple degradation of data
to a total loss of data. So we decided if the electromagnet testing works (get the swing moving),
we will use “EM shielding”. Shielding is typically applied to isolate electrical devices from the
'outside world' by blocking radio frequency electromagnetic radiation (also known as RF
shielding).
So continuing on, the calculations that we did is that we work backwards to choose the
right specs for the electromagnet. We first calculated the torque exerted by the gear box, which
had a worm gear configuration. The gear box increased the motor torque by a gear ratio of
50:1. After find the torque, we tried solving for the physical dimensions of the electromagnet;
the number of turns and the length (by relating magnetic field and torque as seen in the
equation below).
T= torque
We finally concluded using an electromagnet with a voltage rating of 12V. The electromagnet
was oriented (as seen in figure on the right) in a way to attract a piece of metal. The metal was
mounted on a circular frame. Once induced by current,
the electromagnetic generates a magnetic field. The
more current the larger the field, and the faster the
swing moves. But the test did NOT work unfortunately.
The field drops so fast that it barely moves the swing. We
tried putting it at its maximum rating, but that just ended
up heating up the electromagnet. Thus; the
electromagnet was disregarded and we moved on to the
next step, which was the “push-pull solenoid”.
Figure 4-Electromagnet testing
Figure 5-electromagnet specs
7.1b Push-Pull Solenoid
One might ask, why are we still insisting on using
solenoids? The answer is because one does not have to
worry of anything wearing out. So the next design that
came into mind is to use the push-pull solenoid.
In a push-pull solenoid, the magnetic field can
either be a push or pull type of field. Since the coil is
wound around a plastic spool, the plunger or actuator fits
inside of the spool. Attached to the plunger is a
mechanical lever that can increase the movement of the
"in" or "out" action of the electric solenoid.
Figure 6- push-pull solenoid
What the group had on mind is to make the solenoid give periodic pushes to the swing.
The more current you supply, the harder it pushes and the faster the baby swing. This
component did not work for a couple of reasons. The first reason is because it did not have
enough force to push the swing with and without load. It appears that this kind of solenoid is
used in applications such as in car door locks. The second reason, is because it was overheating.
So we concluded that the best component that would work with the swing is to go with what it
had, a DC motor, except it should be brushless.
7.1c Brushless DC motor
The task of finding a brushless dc motor with similar
specs as the previous motor was difficult. It was difficult
because BLDC motors are expensive. Once we found the
motor we need (RC motor), we also had to look for a speed
controller. This will enable the microcontroller to control the
motor’s speed. Everything worked perfectly with the motor. It
could move the swing smoothly at the speed the user wants
and could handle a load up to 30lbs (5lbs extra than needed).
No overheating issues were present. In addition, we did not
Figure7- brushless dc motor design
need to worry about anything malfunctioning. The project required that the swing is able to
operate for 2 years, and the only thing in the whole electronic system that determines this
‘time interval’ is the motor. So if the motor has no issue in things wearing out, then the swing
can swing as long as it wants. The only problem that arose with this motor was that it is a little
noisy, since it is an RC motor. Other than that, it does the job great.
Figure 8- brushless dc motor used in the project
7.2
Control
Microcontroller: Arduino UNO

16 MHz CPU

PWM, Digital, Analog pins

More libraries and Community support
Microcontroller’s function

Controls the swing’s speed

Reads user input and changes output accordingly
Figure 9- Arduino UNO
Electric Speed Controller (ESC):

Electronically generated 3 phase electric power
Figure 10-Electric Speed Controller
7.3
Music
The music system in the project just needed to be upgraded. The old baby swing had
pre-installed music, and thus offered limited the user with few songs. What the group decided
to do is to add an iPod dock and a SD card reader. The iPod dock would enable the user to play
any music he or she wants. On the other hand, the SD card would have pre-installed music
download stored into it. Thus, if someone does not have any iPod, music is also available on the
swing. In addition, we designed a new volume control and amplification circuit, and used the
same speakers that were there.
7.3a SD card
The SD card that was used was connected to a
microcontroller. The microcontroller powered up the SD
card (red light means ON as seen in figure 8) and managed
the music (choosing between music).
7.3b iPod
Figure 11-SD card
To begin with, an iPod dock charging circuit has been developed as seen in the figures
below. This charging circuit is applicable for the 4th generation of iPod and lower.
Figure 12-iPod charging circuit
Figure 13-iPod pin breakout
As seen in figure 11, the iPod charging circuit requires a 5V input which will be achieved by the
power circuit.
7.3c Volume Amplification & Control
Figure 14-Volume amplify circuit & control
As seen in figure 14 above, the audio output from the iPod gets amplified by a TI OPA551 op
amp in an inverting configuration, and fed to the speaker. The other part of the circuit, which is
the “voltage inverter”, just inverts the 6V coming from the source to supply the negative
saturation voltage (-Vcc) of the op amp.
Figure 15- audio input & output
7.4
Power Circuits
The power circuit powers up the whole electronic system and insures each component gets the
current it needs. The power system was designed to supply 6V and 2A via an adapter to the
whole system.
Figure 16-Power Circuit Diagram
Designing the Circuits:

Keep the power loss to minimum

Voltages need to be brought down in order to meet each component’s voltage
requirement (circuits 1,3 and 4)

Replace voltage dividers with linear voltage regulators (eliminates excessive resistors)

Linear voltage regulators are also known for their efficiency, if designed right
Power loss in a voltage regulator

Ploss = (Vin-Vout)*Iout
Solution

Keep Vin-Vout to minimum

Use “low” VDROP voltage regulators
In addition

capacitors were used in the circuits for transient performance and to reduce voltage
deviation
Circuits:
Figure 17
Figure 18
Figure 19
8
Final Design
After a full year of designing this swing we have settled on a final design. The final
design that we have created is outlined in this section. Each part of this section that follows is a
complete description of all of the new components of our system; components ranging from
the user experience to the electronics that make up our system.
8.1
User Interface
Figure 20
Because we had to completely redesign all of the electronics of this swing we
also had to redesign the user interface to fit our needs as well as the new button placements
that we created. All in all we have a total of three buttons, two switches, a volume control
knob, an iPod dock, and a speed display via a 7-Segment Display.
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8.2
Speed Control: In order for the user to control how fast the swing moves there will be
two buttons on the interface. The buttons that we will have for this are a speed-up
button and a speed-down button. When the user wants the swing to move slower, s/he
will push the speed-down button, and vice versa when they want the swing to move
faster.
Music: To control the music there will be a music button. This button will turn the music
on and off and will also cycle through the pre-programmed tracks. To turn the music
on/off the user will hold the button down for two seconds, and to cycle through the
songs all the user will have to do is push it and then let it go right away.
Carousel Switch: This switch will control the carousel above the baby’s head. There will
be an on and off position.
Power Switch: This switch will control the power for the entire swing.
Volume Control: To control the volume of the swing the user will have a knob to turn,
counter-clockwise to turn the volume down, and clockwise to turn it up.
7-Segment Display: Indicates what speed the swing is moving at.
iPod dock: Dock to connect the iPod to the system.
Micro-Controller
To control our system we decided to go with an Arduino. This was not our original
choice, our original choice being the Texas Instruments Launchpad, however when we started
to test all of our circuits and audio signals we realized that the Launchpad didn’t have enough
pins to control our entire system. Not only did the Launchpad have less pins than the Arduino
but it also had less programming libraries. This last fact proved detrimental to our system,
making it harder and more time consuming to program. As a result we chose the Arduino to
control all aspects of our system. It will control the audio signal, register user input and act
accordingly, control signals to the motor, as well as the 7-Segment Display to indicate what
speed the swing is moving at.
8.3
Motion
After extensive testing with various motors, solid electromagnets, and electromagnetic
solenoids we decided to use a motor to control the motion for our system. We chose a motor
to control the swings motion because it proved to be the most reliable of all of our testing.
When testing the solid electromagnet we discovered that the magnet didn’t have enough
attractive force to get the swing to move at all. When trying to test the electromagnetic
solenoid, we discovered that we received a faulty product because it didn’t meet the
manufacturer’s specifications, provided next to zero force, and had extensive over heating
issues. As a result we chose to use a more reliable, more powerful motor.
Figure 21-Motor and Speed Controller
output signals
8.4
Printed Circuit Board (PCB)
After designing all of our circuits (power circuit, audio circuits, etc.) we had to place
them on a PCB that fit inside of our swing. This PCB will contain all of the buttons used for the
system controls, all of our circuits, the power switch for the system as well as the power switch
for the carousel, the SD card adapter, the 7-Segment Display and will also have a connecting
‘dock’ for the Arduino. The overall outline of the PCB is depicted in the image below.
Figure 22-PCB
8.5
Audio
During the initial design phases we had a number of options when it came to audio.
Initially the user was going to be able to insert a USB with audio files on it, and these files would
be directly downloaded to the swing. However upon trying this method we decided on another
option. The design that we finalized for the audio has two parts; the iPod, as originally planned,
and a pre-programmed SD card with audio files on it.
8.5a iPod Connection
A unique feature that we added to this baby swing was the ability for the user to
connect their iPod as long as they have one of the following models:



iPhone 3G, 3GS, 4
iPodTouch 2,3,4th
iPod Classic 6th
When the user decides that they want to connect their iPod the Arduino will recognize its audio
signal and use it as the default audio signal to be output to the speaker. While the iPod is
connected it will not only be able to play music for the baby it will charge at the same time,
leaving the user with a fully charged iPod when they are done.
8.5b SD Card (Pre-programmed)
The second audio option for the swing we designed is pre-programmed music via an SD
card. The music that will be pre-programmed on the SD card will be a small variety of your usual
baby lullabies. When the iPod is not connected the Arduino will read the music files off of the
SD card and output them to the speaker. With this option the user will be able to cycle through
the pre-programmed lullabies, or have no music playing at all.
9
Testing the Final System
When testing the system that we designed we first had to power and test the PCB using
the same adapter that we would be using in for final product. Once we had the power
connected we turned the power switch on and tested each individual part of the PCB to make
sure all parts were receiving the correct voltages, and to also make sure that we didn’t have any
shorts in our system. Once we made sure that all of the different circuits had the proper
voltages and were working correctly on the PCB we began connecting the various components
of our system to the board to see if they worked properly.
First we tested the carousel to ensure that it operated correctly and at the desired
speed. After determining that the carousel worked properly we then connected the iPod. Once
we tested the iPod and made sure it charged, and was able to output audio to the speaker, we
then connected the Arduino to ensure that it was powered like we designed it. After connecting
and testing the Arduino we then tested each of the controlling buttons to make sure that they
passed voltage to the Arduino to let the system know the user was inputting ‘data’. After
making sure all of the buttons were working properly we made sure that the PCB could power
the motor effectively. Last but not least we connected the 7-Segment Display to the PCB and
tested it using the different speeds of the motor. Through the use of these simple tests we
were able to discern that our final product indeed worked as it was designed.
Appendix
Appendix A: Project Plan
1 Executive Summary
We live in a time and environment in which creativity and reliability significantly
characterize our new technologies and innovations. Our senior design team has chosen the task
of redesigning the electronics of a baby swing, transforming it into a more reliable and creative
product. Reliable, whereby the product will last longer and be more practical in comparison to
other baby swings, creative by using new technologies that are more efficient and do the job
better. The whole redesigning process should cost less than $15.
The senior design team consisted of 2 Electrical Engineers, 1 Computer Engineer, and 1
Software Engineer. The Electrical Engineers were responsible for designing the system’s
required circuits, and testing. On the other hand, the computer and software engineer’s took
care of controlling the whole electronic system and getting the components interactive.
In the following document, the project team will outline the overall design of the
custom information status board. This document will walk you through every detail of the
product until reaching the final design.
2 Problem Statement
This project focused on redesigning the electronics of a baby swing. The problem with
the previous swing was that the motor was non-functional. Our group was assigned to replace
the motor with another component that is more reliable and adding more features to the
existing design.
The new design should be as follows; be able to download music from a memory stick so
that any song can be played as the baby swings. Be able to swing at a constant speed regardless
of the baby’s weight and remain rigid by changing to different speeds. Be able to operate
continuously for 15 hours a day 7 days a week for 2 years. Finally; the last requirement was to
be able to sell the swing for less than $15.
So we began by dividing the project into four main parts. The four parts were as follows;
power circuit, microcontroller, motion, and music. The power circuit powers up the whole
electronic system and insures each component gets the current it needs. The power system
was designed to supply 6V and 2A via an adapter to the whole system. Secondly is the
microcontroller, which was the center point to all other parts of the electronic system. It
controls the swing’s motion, music, and carousel. Thirdly; the brushed DC motor was replaced
with a brushless DC motor simply because it lasts longer and does the job much better. Finally;
in regards to music, we installed an iPod dock that plays any music the user wants.
3 General Solutions
We divided our group tasks into two sections. One section will be taking care of the
programming part of the project. This section will be mainly programming the microcontroller
to do all sort of tasks such as controlling the motor’s speed and motion, and managing the
music. The other part of the group, which are all electrical engineers, will be responsible for the
motor and installing it in the swing, and designing circuits such as power circuit, volume
amplification circuit, voltage inverting circuit and other electrical related components.
In regards for fixing the baby swing, the only thing that needed to be fixed was the
brushed motor. The solution to this problem is to replace the motor with a better and a more
efficient solution, a brushless dc motor. Instead of letting the motor pull back and forth to get
the swing up to both sides, we will program it in a way that makes it pull the swing on one side
and then releases it. Once it pulls it, it then releases it for a certain number of periods and then
pulls it again, and again releases it and so forth and so on. This means that less power will be
used to get the swing moving while avoiding the potential danger of the motor overheating. In
addition, one does not need to worry about anything wearing out or not working as in the
brushed motor. In regards to the music, the iPod dock will be used to read the sound signals
and send it to the speakers.
4 INTENDED USERS/INTENTDED USES
Intended Users: Our product intended users are parents with young children from newborns to
the age of two. This product will be put to use for young children. It is intended to relax and
comfort them with music and a steady continuous motion.
5 SYSTEM BLOCK DIAGRAM
6 SYSTEM DESCRIPTION
6.1 Operating Environment
This baby swing will not be designed to work in every environment imaginable. Because
the swing is meant for babies, it will be designed to be operated primarily indoors where
the environment can be easily monitored and quite possibly outside when the weather
permits. (i.e. sunny and little wind).
6.2 User Interface Description
The user interface for this baby swing will be relatively simple. There will be a variety of
buttons to control various functions of the swing. These buttons will include, but are not
limited to: music selection, music volume control, and swing speed. The swing will also
have a USB/IPod input in order to play any song the user desires.
6.3 Functional Requirements
FR 01 - The input power (10-20) W
FR 02 - The system input voltage (5-12) V DCV
FR 03 - The motor should be able to deliver a torque for up to 30pounds.
FR 04 - The new system shall be able to maintain full operation for 15 hours/ day for two
years.
FR 05 - The maximum speed of the system is 1.5 m/min and the maximum angle of
rotation 200
FR 06 - The PCB board (microcontroller) controls the motor, music, and the power input
of the system
FR 07 - The system should allow the user to select the swing’s speed of and the music.
6.4 Non-functional Requirements
*
The system should be easy to locate in the house under reliable temperature
environment
*
The child should be safe and secured
*
The system should not cause any risk to the specified load of the baby
6.5 Constraints
The baby swing has the following constraints:



The system should have a PC Board that is designed to have software
uploaded
The project must be completed by the end of a two semester time period
Unit should be manufactured as cheap as possible ($15 or less)
6.6 Technologies
Microcontroller Board: Texas Instruments Launchpad
Step Motor: NEMA 23, 3.84V
Solenoid: 12V DC 45N Electromagnet Solenoid 10mm Stroke
Music: An iPod dock is used to obtain the sound signal and transmit it to the swing’s
speakers.
7 DELIVERABLES / EXPECTED END PRODUCT
For this project our final expected product will be a working, reliable, safe and economicallyfriendly baby swing. A motor will be directly connected to the swing through a gearbox, and will
push the swing only when the speed is slower than the desired speed. A speed sensor will gather
the current speed of the swing and return it to the microcontroller. A microcontroller will control
the power of the motor based on the speed of swing. In order for the system to be economicallyfriendly, the motor will only work less than 10 seconds a minute. For safety, the swing will have
a feature that allows it to remain rigid against outside forces. The product is also equipped with
an IPod player and stereo speakers.
8 RESOURCES
Internet
ECpE Lab Resources (Hardware and Software)
ECpE Faculty
Senior Design Funds
9 Economic Model
The targeted market for this baby swing is all the new parents across the United States. There are
approximately 4 million babies born each year in the United States and no matter what race or
gender they are, they always need a baby swing. The trouble is how to decide which baby swing
is right for their specific baby. As a result of this we have to design the swing so parents will
want to choose our swing over any others currently on the market. There are many ways to do
this but perhaps the best way to accomplish this is to appeal to the protectiveness of new parents.
To do this we made perhaps the most important feature of our baby swing the fact that it will be
extremely safe for the baby. We recently spoke with several new parents about this project and
they showed very strong interest in the design features that we are adding; these parents even
went so far as to say that if our product were to go on the market they would very likely throw
away their current baby swing and buy ours without hesitation.
10 Project Management
10.1 Work Breakdown Structure
Rashed Alfalasi - Team Leader
-
Microcontroller programing
iPod dock
Motor control
PC board design
Yezhou Fang
-
Pre-stored Songs
Microcontroller programing
iPod dock
Matthew Seymour
-
PC board design
Design the motor/ electromagnet, and calculate the requirement for them.
Volume amplification circuit
Ahmed Alharmoodi - Motor + Electrical Design
-
Design the motor/ electromagnet, and calculate the requirement for them.
Designed Power Circuits
Volume amplification circuit
Ayoub Ali – Motor + Power
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Power Supply
Find a capable motor / electromagnet in the market
10.2 Statement of Work
1. Problem Definition
1.1 Objective
1.1.1 Define the goal, requirements, vision, and any constraints of the project
1.2 Approach
1.2.1 Meet client and the adviser to understand their vision and any constraints
1.2.2 Consider working environment freedoms and limitations
1.2.3 Consider desirable user features
1.2.4 How to improve the product?
1.3 Expected Results
1.3.1 Know the problems with the old design and find solutions
1.4 Subtasks
a. Problem Definition Completion
c. Research how to control a motor, and the right motor
2. Technology Consideration and Selection
2.1 Objective
2.1.1 Find available technologies for this project and select an inexpensive
reliable choice
2.2 Approach
2.2.1 Research options for stepper or brushless motors that meet our calculations
and requirements.
2.2.2 Consider the processing and software implementation demands of the
technology
2.2.3 Find sophisticated and usable implementations of the most ideal
technologies
2.2.4 Look for possible ways to implement the project
2.3 Expected Results
2.3.1 Selection of an inexpensive Microcontroller board, which can control the
motor and the music
2.3.2 Find a stepper or brushless motor
2.4 Subtasks
a. Identify possible technologies
b. Technology research and selection
c. Research motor designing
3. Product Design
3.1 Objective
3.1.1 Create an initial complete design of all components connected together
3.2 Approach
3.2.1 Confirm design needs of project with clients and advisor
3.2.2 Identify components of block diagram
3.2.3 Identify and/or define interfaces of hardware
3.2.4 Define software for the Microcontroller
3.2.5 Generate complete initial Design Document
3.3 Expected Results
3.3.1 Complete design such that all aspects of the block diagram may be fully
implemented into a functioning product
3.4 Subtasks
a. Identification of Design Requirements
b. Design Process
c. Documentation of Design
4. Production Implementation, Redesign, and Repeated Testing
4.1 Objective
4.1.1 Generate everything defined in Part 3 such that a working prototype may be
tested.
4.2 Approach
4.2.1 Create functioning version of each component according to the Design
Document
4.2.2 Test to confirm current specifications are met
4.2.3 Identify improvements that can be added to increase reliability and
4.2.4 Define feasible implementation of improvements
4.2.5 Include improvements into Design Document
4.2.6 Repeat 1-4 while there is time remaining before final testing occur.
4.3 Expected Results
4.3.1 A fully implemented design that meets the requirements
4.4 Subtasks
4.4.1 Plan for generating components
4.4.2 Generate components
4.4.3 Confirm specifications are met
4.4.4 Continued Improvement
5. Product Testing and Validation
5.1 Objective
5.1.1 Extended testing period while the product evolves. Test to ensure the
highest quality and closest match to all requirements as possible
5.2 Approach
5.2.1 Define comprehensive test plans for the Baby Swing
5.2.2 Develop tests cases
5.2.3 Test execution
5.2.4 Test evaluation
5.2.5 Revise and repeat test cases and execution as product evolves
5.2.6 Documentation of testing
5.3 Expected Results
5.3.1 A refined, reliable product that meets or exceeds all requirements.
5.4 Subtasks
5.4.1 Create test plan and test cases
5.4.2 Test execution and evaluation
5.4.3 Continue and evolve testing while development evolves
5.4.4 Create testing documentation
10.3 Risks / Risk Mitigation
The current considerations of risk areas are:
 Motor failure
 Child might fall from the swing
 Losing a team member
 Requirement for more part, which increases the total cost.
 Not having reliable parts
 Finding last minute design flaws
10.4 Costs
Items
Cost
Bulk Cost
Motor
$15.95
$2.00 (5,000+)
PCB
$50.00
$3.92 (15,000+)
PCB parts
$36.03
$2.47 (100,000+)
Arduino
$15.00
$7.87 (100+)
iPod Dock
$14.99
$0.3 (10,000+)
Total
$16.56
10.5 Project Schedule
Weeks
Research parts
Order parts
Project plan
Motor/Magnet
research
iPod Dock
Motor/Magnet
testing
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Appendix B: System User Guide
Improvements & Suggestions
Due to the constraints, we only have a few months to do this project, and our product
should be product less than $15.
Keep constant speed:
Currently, we control the speed of the motor to keep the swing working at a constant
speed. An alternative way to do that is adding a speed censor as a input to the microcontroller, turn off the motor when the speed is over the setting speed, and turn on the
motor when the speed is less than the setting speed.
Silence motor:
The major problem of current design is we use a motor which is used for toy cars and
toy helicopters. Although it provide enough power for swing, it make noisy. We still look
for a better motor which provide huge power and also silence.
Micro-controllers:
Currently, we using Arduino as our Microcontroller. It provide lots of libraries and have a
good community, which provide us a quick way to look up the issues we met and solve
it very quick.it’s really good for work as a project, but it doesn’t very good for mass
production. the problem is it’s too expensive. While there are lots of microcontrollers on
the market which have the same specs as Arduino does. In the further we are going to
replace the Ardunio with a cheap microcrontoller.
Music:
Due the budget and limitation of plastic desgin by the orginal swing. The current desgin we
have for the music is only mono sound. The sound from iPod is either left or right. As long
as it does not interrupt the baby and also the speaker does not provide a professional
sound, we think its fine for it and we only implement the curcuit for one speaker. But the
curcuit can be extand to the stereo sound, which have both left and right.
Warnings
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Maxmim weight is 20lbs. Do NOT overload, which may cause serious issues.
Keep it indoor usage only. The product is not waterproof.
Trun off the baby swing if it does not swing as exptected.
Do NOT put your baby on the swing if you don’t know how to operate the baby
swing.
the power is only accept 100-130V. The product may cause serious issues if you
plug it in those countries which use 220V.
Physical User Interface

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iPod Dock
Power Controls
Carousel Controls
Music Controls
Volume Controls
Motion Controls
Speed Read Out (1-3)
Appendix C: Definitions
Microcontroller - A microcontroller is a small computer on a single integrated circuit containing
a processor core, memory, and programmable input/output peripherals.
Voltage - an electromotive force or potential difference expressed in volts.
SD card - Secure Digital is a non-volatile memory card format for use in portable devices, such
as mobile phones, digital cameras, GPS navigation devices, and tablet computers.
Voltage regulator - a transformer whose voltage ratio of transformation can be adjusted.
iPod - a portable electronic device for playing and storing digital audio and video files.
Arduino - Arduino is a single-board microcontroller to make using electronics in
multidisciplinary projects more accessible.
Mono Sound - Monaural or monophonic sound reproduction is single-channel. Typically there is
only one microphone, one loudspeaker, or channels are fed from a common signal path.
Stereo Sound - Stereophonic sound or, more commonly, stereo, is a method of sound
reproduction that creates an illusion of directionality and audible perspective.
Speed sensors - machines used to detect the speed of an object, usually a transport vehicle.