International Journal of Computer Applications (0975 – 8887)
Volume 71– No.21, June 2013
Automatic E-Baby Cradle Swing based on Baby Cry
Misha Goyal
Dilip Kumar
ACSD, CDAC
Mohali, Punjab INDIA
ACSD, CDAC
Mohali, Punjab INDIA
ABSTRACT
There is a need to develop a new low cost indigenous
electronic cradle because the existing cradles are imported and
costly. This paper presents the design and implementation of a
new indigenous low cost E-Baby Cradle that swings
automatically when baby cries, for this it has a cry analyzing
system which detects the baby cry voice and accordingly the
cradle swings till the baby stops crying. The speed of the
cradle can be controlled as per the user need. The system has
inbuilt alarm that indicates two conditions – first when the
mattress is wet, which is an important parameter to keep the
baby in hygienic condition, second when baby does not stop
crying with in a stipulated time, which intimated that baby
needs attention. This system helps parents and nurses to take
care of babies without physical attention.
General Terms
E-Baby cradle, low cost, indigenous.
Keywords
Automatic Baby Cradles, Wet Sensor, Cry Analyzing System.
1. INTRODUCTION
Parents in the present world are busy in their professional life,
so they do not get sufficient time to take care of their babies.
It may be expensive for the household to afford a nanny.
Today’s woman has to manage home along with their office
work simultaneously. After long working hours, they have to
take care of the home along with the baby. They may not get
enough time to swing the cradle manually and sooth the baby.
Moreover, in today’s life style, it is very difficult even for the
housewives to sit nearby their infants and sooth them
whenever they cry.
Hospitals have neonatal and maternity units. Nurses in these
units have to take care of baby and sooth them whenever they
cry.
The system is designed to help parents and nurses in infants
care. The design aims at following points:
1.
Cradle starts swinging automatically when baby cry
and swings till the baby stops crying.
2.
Sounds an alarm when mattress gets wet.
3.
Sounds an alarm if baby cries for more than a
stipulated time indicating that baby needs attention.
2. RELATED WORK
Steven Bang designed automatic baby rocker having a noise
sensor to detect baby cry. Noise sensor consists of Electret
MIC with a pre amplifier (2n3904 transistor). Signal from
noise sensor is fed to microcontroller Arduino ATmega 328,
which is used to control the DC motor. Few colorful lights
made up of LED are used to entertain the baby while being
rocked. Mabuchi RE-260RA DC motor with Tamiya 6 speed
gear box is used to create the rocking motion of the crib with
gear ratio of 505.9:1 [1].
Yang Hu proposed an algorithm for adjusting the bassinet
swaying extent by the sensor signals. The bassinet is made up
of an adaptive swaying device and other sensors network.
While baby is crying, the sensors network can judge the
reason according to detecting parameters, giving the different
signals to control circuit. At the same time, the bassinet starts
to sway slightly. The swaying rhythm can be adjusted
according to parameters from baby status. They used three
pressure sensor located in the bassinet bottom, one at the
centre and others at left and right of the bottom [2].
Marie R. Harper invented a crib adapted to be rocked
automaticaly. Once the crib is manualy tilted in one direction
and released, this permits the inertia to actuate the locking and
actuating arms to operate under the biasing force of spring in
conjuction with the gear. Thus spring loaded motor begin to
operate and the lever arm is oscillated in back and forth
movement. This provides the same effect as would be
achieved by the mother rocking the crib containing the baby.
Oscillation of crib is stoped when the slightest resistance is
incurred [3].
Gim Wong presented an Electronic device that can be
attached to conventional pivotally mounted type crib. Which
is actuated by baby cry voice picked up by the microphone
giving short throw type rocking action to crib. Very similar to
a person rocking the crib by pushing and pulling on the foot or
headboard . There is a sensitivity control so that baby voice
only actuate the rocking action and a timer to controlle the
duration of rocking action [4].
Chau-Kai-Hsieh proposed a baby cry recognizer which
includes an amplifier circuit for amplifying a received sound
signal. In response to the amplified sound signal, a pulse
generator circuit generates a pulse signal having zero
crossings which are aligned with zero crossings of the
amplified sound signal. The pulse signal, in turn, is inputted to
a signal recognition circuit. The signal recognition circuit
outputs a signal indicating that a baby’s cry was detected [5].
Anritha Ebenezer gives an aproach to design a baby cradle
consisting of cry analyzing system which detects baby cry.
According to sound intensity cradle swings. It has six rocks
per minute. It has wet sensor to indicates baby wets, whenever
baby wets resistance would change thus sending a signal.
Other sensors include temperature sensor to display baby
temperature, respiratory sensor that sends a signal in apnea
condition. GSM modem via RS232 is used to send msg to
parents in case baby does not stop crying with in a particular
instant of time [6].
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International Journal of Computer Applications (0975 – 8887)
Volume 71– No.21, June 2013
3. BASIC PRINCIPLE
Wet Sensor
Alarm
Principle behind cradle swing stays in comparing the baby cry
generated sound level in dB 𝑥 with a preset value 𝑦 and it
swings if 𝑥 is greater than 𝑦.
Signal
conditioning
The amplified signal is generated from the voice input. This
amplified signal is then converted into a digital signal from
which sound level 𝑥 is calculated.
𝑣𝑖𝑛
𝑠𝑜𝑢𝑛𝑑 𝑙𝑒𝑣𝑒𝑙 𝑥 = 20 log
𝑑𝐵
𝑣0
µc
Driver
Circuit
Motor
Baby
Bassinet
MIC
Where,
Fig 2: Block diagram of E-Baby Cradle
Vin = Voltage (ADC count) when baby is crying.
V0 = Average reference voltage (ADC count) when baby is
not crying.
The preset value 𝑦 is set initially as part of configuration of
the system. It is the least value among the samples of baby cry
sound levels and it can be modified in future as and when
necessary.
4. ALGORITHM
Start
Incoming signal value is (x)
When baby cries in the cradle, microphone detects it and
converts the sound signal into electrical signal. The electrical
signal is then fed into amplifier. Condenser microphone is
used to detect the baby cry. This has two plates and one of
these plates is made of very light material that acts as a
diaphragm. The diaphragm vibrates when struck by sound
waves, changing the distance between the two plates and
therefore changing the capacitance and producing electrical
signal.
Op-amp is used as amplifier for signal conditioning circuit.
The electrical signal from MIC is provided as input to the
circuit. The output from MIC is get amplified by op-amp so
that it can be used by microcontroller.
No
value (y)
5.1 MIC
5.2 Signal Conditioning
Take samples of sound level
from baby cry
Input least value
from these samples
as preset signal
The main designing blocks of system are as follows:-
Is
mattress
wet?
Yes
Alarm
No
5.3 Wet Sensor
It is a moisture sensor having two leads in mesh form. One
lead is connected to microcontroller through pull up resistor
and other is connected to ground. When baby wets the
mattresses the two leads become short and signal is send to
microcontroller. This microcontroller in turn sends the signal
to the alarm. This system helps in keeping the baby in a
hygienic environment.
5.4 Microcontroller
PIC16F73 is used to receive the amplified signal and to
convert this amplified signal to digital signal. Microcontroller
controls the driver circuit that starts a motor and sways the
baby bassinet according to the input signal.
Is
x>y?
Yes
5.5 Alarm
Swing
cradle
Alarm will be generated on two conditions:
Yes
1.
When mattress is wet, indicating parents that
mattress and baby clothes need to be changed.
2.
When baby cries for a specific time. For example,
baby cries and baby bassinet swings for 2 min alarm will be
generated. This indicates parents that baby needs attention.
Is swing
time
(t)>2 min
& x>y?
5.6 Driver Circuit
Motor driver circuit supplies essential power to drive the
motor. This isolates the PIC and ICs from electrical problems.
No
5.7 Motor
Stop
Fig 1: Flowchart
5. BLOCK DIAGRAM
Fig 2 shows the basic block diagram build around PIC16F73.
Heavy duty sewing AC motor of 8500 RPM, 220 volts is used
to sway the baby bassinet. It is connected to PIC through a
driver circuit. Also, motors tend to be electrically noisy
(spikes) and can pass power back into the control lines when
its direction or speed is changed. This EMF is created by
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International Journal of Computer Applications (0975 – 8887)
Volume 71– No.21, June 2013
motor brushes. The driver circuit protects PIC from back
EMF.
5.8 Baby Bassinet
Baby bassinet is the infant bed. This is connected to a motor
which sways the baby bassinet based on the power it receives
from the driver circuit.
6. DESIGN OF CRADLE
Design of E-Baby Cradle is a challenge in itself. The system
is designed so that baby feels comfortable and gets a good
sleep. It can be used for babies aged between 3 months to 2
years. Mechanical design is such that it provides smooth and
gentle rhythmic motion just like parents manually swings the
cradle. Also, when cradle stops swinging it does not give jerks
to baby.
As shown in Fig 3 and Fig 4, baby bassinet is made of wood
with dimensions: length 90cm, height 25cm and breadth
49cm. Bassinet is mounted on mechanical system which
consists of base frame, motor, connecting rod, roller and a
belt. Motor has a small drive roller with diameter 2cm. The
motor drives larger drive roller with diameter 40cm which
reduces rpm and gets desired torque. The larger wheel is
connected to base of bassinet with connecting rod. The
mechanical system has low wear and tear and requires less
maintenance.
Fig 4: Top view of cradle design from an angle
Fig 5 shows the electronic board connected to cradle which
consist of transformer, microcontroller and peripheral devices
including LCD, op-amp, wet sensor, relay and switches. A
transformer steps down 220V AC to 15V AC. Further
LM7805 steps down 15V DC to 5V DC which inputs to
microcontroller and other peripherals.
Fig 5: Electronic board connected with cradle
Fig 3: Top view of cradle design
Fig 6 shows the circuit diagram. Two OP-07 op-amps amplify
MIC output, which is connected to RA0 pin of
microcontroller. Two switches are coupled to RC0 and RC1
pins of microcontroller to set the preset value. A 16 x 1 LCD
is connected to PORT B that shows the sound level of baby
cry voice and also shows preset value set by user.
Wet sensor is connected to RC2 pin and motor is connected to
RC7 pin through driver ULN2803 and relay. Buzzer is
connected to RC5 pin through ULN2803.
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International Journal of Computer Applications (0975 – 8887)
Volume 71– No.21, June 2013
Fig 6: Circuit diagram
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International Journal of Computer Applications (0975 – 8887)
Volume 71– No.21, June 2013
7. TEST RESULTS
8. RESULTS
We show test results of a real example in the section. The
developed prototype is shown in Fig 7.
Here one baby boy of 7 months old and another baby girl of 6
months old are considered for the analyses of their cry voices.
Three samples of each of the baby cry voice are taken at
different instant of time. The voices are recorded in .amr
format and then the sound level generated from these voice
signals is analyzed. From analysis it is identified that each
baby’s cry voice sound level varies. Thus accordingly the
system is to be configured first time by setting the preset
value. This system is so user friendly that user can preset the
value himself. Table below shows the different sound levels.
Here absolute values are taken.
Table 1: Sound levels
Sample 1
Baby Boy
(dB)
23
Baby Girl
(dB)
33
Sample 2
21
30
Sample 3
25
36
Samples
Fig 7: E-Baby Cradle
Here three samples of sound levels of baby cry voice sound
level are taken i.e. 24dB, 27dB and 21dB. Least value 21dB
among the three sound levels is set as preset value. Now in
Fig 8, baby is quiet. Even when the baby is quiet there is an
input due to environmental noise ranging 0dB-5dB which is
less than the preset value 21dB and therefore cradle does not
start swinging.
9. CONCLUSION
Looking after babies is hard problem worldwide. Babies are
society future. This system emphasizes the importance of
child care. The above designed system is economical and user
friendly and very useful for working parents and nurses. They
can manage their work efficiently.
This system can be enhanced with more features like baby
rotating toy with music and camera. Parents can monitor their
baby live via 3G.
With the development of technology day to day work has
been eased for parents along with baby care. Otherwise,
mother’s lap would be best cradle for baby.
10. ACKNOWLEDGMENTS
This work is supported by CDAC (Center for Development of
Advanced Computing) Mohali, India. I am thankful to Mr. J S
Bhatia and Dr. Dilip Kumar for their support and guidance.
Fig 8: Baby is quiet
When baby starts crying as is Fig 9, an input due to baby cry
voice and environmental noise is detected in range 25dB35dB which is greater than the preset value 21dB and
therefore cradle starts swinging. When baby stops crying,
cradle stops swinging slowly so that baby totally goes to
sleep.
11. REFERENCES
[1] Steven Bang; Richard Lam; Natallia LoCicero; , “Rock
Me Baby: The Automatic Baby Rocker” Project for, San
Jose State University, Department of Mechanical and
Aerospace Engineering, May 17, 2011.
[2] Yang Hu; Weihua Gui; , “Adaptive Sway Control for
Baby Bassinet Based on Artificial Metabolic Algorithm”
School of Information Science and Engineering, Central
South University, China.
[3] Marie R. Harper; La Mirada; Maxine R. Blea; ,
“Automatically rocking baby cradle”, US 3769641, Date
of Patent: Nov. 6,1973.
[4] Gim Wong, “Automatic baby crib rocker” US 3952343,
Date of Patent: Apr. 27,1976.
[5] Chau-Kai-Hsieh; Chiung Lin; Taiwan; , “Baby Cry
Recognizer” US 5668780, Date of Patent Sep. 16,1997.
Fig 9: Baby crying
IJCATM : www.ijcaonline.org
[6] Anritha Ebenezer; Anupreethi. S; , “Automatic Cradle
Movement for Infant Care” Undergraduate Academic
Research Journal (UARJ), ISSN : 2278 – 1129, Vol.-1,
Issue-1, 2012.
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