Lab 1 – DFM Product Specification - 1 -
CS 411W Lab II
Prototype Product Specification
For
Don’t Forget Me
Prepared by: Daniel Holloway, DFM Inc.
Date: 03/05/2008
Lab 1 – DFM Product Specification - 2 -
Table of Contents
1 Introduction ...................................................................................................................... 4
1.1
Purpose.................................................................................................................... 5
1.2
Scope ....................................................................................................................... 8
1.3
Definitions, Acronyms, and Abbreviations ............................................................ 9
1.4 References ................................................................................................................... 11
1.5 Overview ..................................................................................................................... 12
2 General Description .................................................................................................. 12
2.1 Prototype Architecture Description ............................................................................ 12
2.2 Prototype Functional Description ............................................................................... 17
2.2.1 Prototype Functional Objectives ...................................................................... 17
2.3 External Interfaces ...................................................................................................... 18
2.3.1 Hardware Interfaces ......................................................................................... 18
2.3.2 Software Interfaces .......................................................................................... 24
3 Specific Requirements .............................................................................................. 25
3.1 Functional Requirements ............................................................................................ 25
3.1.1
DFM system is activated and goes through self-test ................................ 25
3.1.2
Detecting occupancy ................................................................................. 27
3.1.3
Detecting unsafe conditions ...................................................................... 29
3.1.4
Resetting the DFM system ........................................................................ 29
3.2 Performance Requirements ......................................................................................... 30
3.2.1
Test algorithms.......................................................................................... 31
3.2.2
Occupancy detection ................................................................................. 31
3.2.3
Unsafe conditions detection ...................................................................... 31
3.2.4
Resetting the DFM system ........................................................................ 32
3.3 Assumptions and Constraints ...................................................................................... 33
3.3.1 Assumptions..................................................................................................... 33
3.3.2 Constraints ....................................................................................................... 34
3.3.3 Dependency...................................................................................................... 34
3.4 Non-Functional Requirements .................................................................................... 35
3.4.1 Maintainability ................................................................................................. 35
3.4.2 Reliability......................................................................................................... 35
4 Appendix ........................................................................................................................ 35
4.1 Appendix ..................................................................................................................... 36
List of Figures
Figure 1. Major functional component diagram of the DFM system (Hernan Gonzales
2007 design) ........................................................................................................................ 7
Figure 2. Phase 1 prototype major functional component diagram .................................. 13
Figure 3- NI 6009 DAQ ................................................................................................... 19
Figure 4- Thermistor......................................................................................................... 19
Figure 5- Pulse oximeter clipped on a finger ................................................................... 20
Lab 1 – DFM Product Specification - 3 Figure 6- Microphone ....................................................................................................... 20
Figure 7- Push button ....................................................................................................... 21
Figure 8- Pressure sensor.................................................................................................. 22
Figure 9. Phase 1 prototype motion sensor circuit board ................................................. 22
Figure 10- Laptop ............................................................................................................. 23
Figure 11- National Instruments LabVIEW development environment ......................... 24
Figure 12. Phase 1 prototype test algorithm ..................................................................... 27
Figure 13. Phase 1 prototype major life detection algorithm ........................................... 28
Figure 14- Phase 1 prototype detail detection algorithm.................................................. 30
List of Tables
Table 1. Feature comparison between full product and prototype............................... 15-16
Table 2- Assumptions and Constraints table for the DFM system prototype ................... 33
Lab 1 – DFM Product Specification - 4 -
1 Introduction
A national database, Kid and Cars, tracks deaths and injuries to children left
unattended in motor vehicles. Kid and Cars’ data shows there were 942 injury incidents
involving kids and automobiles in the year 2007. (Kids and Cars, 2007) Also, the data
shows out of the 942 incidents there were 231 fatalities. Furthermore, there were reports
of 9,100 children treated in emergency rooms due to non-traffic incidents. Additionally,
there are several issues contributing to non-traffic incidents involving vehicles and
children. The statistics include children left in a vehicle’s passenger compartment in hot
weather or who lock themselves in the trunk of a vehicle, children strangled by a
vehicle’s power window or sunroof, children killed or injured as a result of a vehicle
backing up, and children killed or injured as a result of vehicle-generated carbon
monoxide. Out of the total number of non-traffic fatalities in the year 2005, 23% were
due to children left alone in vehicles during hot conditions. (Kids and Cars, 2007)
Additionally, 49% of child fatalities due to being backed over by a vehicle will diminish
because of new solutions coming on line that utilize camera technology. The information
regarding child deaths due to vehicle rollover was not available at the time these statistics
came out; therefore, the percentage should decrease for these incidents; however, the
percentage due to hyperthermia will increase.
The Department of Geosciences (DOG) states that it is life threatening when a
human’s body temperature reaches above 104°F. (DOG, 2007) When a human’s body
temperature reaches 106°F, brain death begins. When one’s body temperature reaches
Lab 1 – DFM Product Specification - 5 113°F, death is nearly certain. It does not take long for a vehicle to reach temperatures
damaging or fatal to humans in the summer. When the temperature outside is 80°F, the
temperature inside a parked vehicle can be 99°F within 10 minutes. Subsequently, in 20
minutes the temperature is 109°F, 30 minutes the temperature inside is 114°F, 40
minutes the temperature is 118°F, 50 minutes the temperature is 120°F, and 60 minutes
the temperature is 123°F. Internal vehicle temperatures above 122°F can cause rigidity in
the muscles, followed by death for humans.
Don’t Forget Me (DFM) is a vehicle health and human occupant detection
system to monitor unsafe conditions, and was conceived by the Old Dominion University
(ODU) CS410 Blue Group. DFM is a system for detecting and preventing unsafe
conditions for occupants that are not capable of caring for themselves and are left alone
in a vehicle. What will be provided to the customer is a patent that can be licensed by a
company for each vehicle the DFM is installed in. The DFM system will provide a vast
array of sensors, coupled with advanced algorithms to determine a more accurate
occurrence of human life at risk and provide an alert system (Holloway, 2008).
1.1 Purpose
The purpose of creating a system such as the DFM is to mitigate the deaths and
injuries of occupants left in a vehicle in hot conditions. The DFM system is a vehicle
health system that monitors occupancy, as well as detect environmental conditions that
are harmful to an individual. The DFM system incorporates an array of sensors thus
reducing the chance of false alarms.
Lab 1 – DFM Product Specification - 6 Figure 1 illustrates the major functional components of the DFM system. The
diagram identifies twelve major functional pieces. The first functional component is a
CO2 sensor that detects CO2 in the compartment of the vehicle. The second functional
component is a temperature sensor. The temperature sensor detects the temperature in the
compartment of the vehicle and is used to verify that a safe temperature exists. The third
functional component is a microphone. A microphone is utilized to detect noise in the
compartment. Within the noise detected, a flag is set if the signal reaches a certain
decibel (dB). The fourth functional component is an accelerometer. The accelerometer
detects small vibrations in the compartment of the vehicle and when integrated with
unique software can analyze and determine if the vibration is that of a heartbeat. A fifth
functional component is a motion detector. The motion detector consists of a receiver and
transmitter. The motion detector activates if a movement of more than one centimeter
occurs in the compartment of the vehicle. The sixth functional component is a pressure
sensor. The pressure sensor acts as a transducer and converts pressure into a voltage
signal that is received from event listeners and created using algorithms. The first six
components are the sensors used to determine a safe environment and occupancy within
the compartment of a vehicle. Through the use of complex algorithms the signals are
given a certain weight to determine the state of an alarm. The seventh and eight
components are an RF transmitter and receiver. The transmitter is located in the vehicle
while the receiver is part of a key fob. A signal is constantly sent if the vehicle is turned
off and the reset button has not been set. The ninth component is the reset button in order
to deactivate the key fob for instances where the condition is needed (i.e. pumping gas).
The tenth functional component is a CPU for executing the advanced algorithms in order
Lab 1 – DFM Product Specification - 7 takes the signals from all of the sensors to give them value to determine occupancy and
unsafe conditions. The eleventh and last component is an alarm in order to alert the care
giver that an occupant is still in the vehicle or unsafe conditions exist.
Figure 1. Major functional component diagram of the DFM system (Hernan Gonzales
2007 design)
Lab 1 – DFM Product Specification - 8 -
1.2 Scope
The prototype of the DFM system is designed to demonstrate the feasibility of a
system utilizing a vast array of sensors to detect occupancy and unsafe conditions, while
mitigating false alarms. The first functional objective is to demonstrate the use of various
sensor technologies. The demonstration, via LabVIEW, indicates the sensors are
detecting the environmental conditions that the sensors are designed. First, a temperature
sensor shows the temperature in real time through a virtual instrument representing a
thermometer. Second, a motion sensor shows movement in real time through a virtual
instrument that is represented by a light emitting diode (LED). The LED only turns off
when motion decreases for a predefined period of time. Third, a pressure sensor senses
pressure from an occupant sitting on the seat of the vehicle and sends a signal to the DFM
system. The effect is shown by a LED lighting up in a LabVIEW virtual instrument (VI).
Fourth, a pulse oximeter sensor aids in determining life in a vehicle. The task is achieved
through attaching the pulse oximeter to an individual’s finger to detect the presence of a
pulse (Holloway, 2008).
The second objective is demonstrating the interoperability of the array of different
sensors utilized in this system. This objective is achieved with the assistance from virtual
instruments created using LabVIEW. Also, complex algorithms designed to receive the
signals from the vast array of sensors analyzes the incoming signals to determine if
harmful conditions exist. For example, when the temperature rises above 90 º F, for three
Lab 1 – DFM Product Specification - 9 minutes, and if the temperature falls to 30 degrees Fahrenheit for three minutes the DFM
system sends a signal to sound an alarm (Holloway, 2008).
The third and last objective is to demonstrate that the DFM system provides a more
accurate means of determining if an occupant is left in a vehicle by their caregiver than
other alarm systems. Additionally, the DFM system eliminates false alarms from
occurring that can take up personnel resources and equipment, ultimately costing
taxpayer’s money (Holloway, 2008).
1.3 Definitions, Acronyms, and Abbreviations
Accelerometer- A device that measures the force on a sensor. Variations in the
accelerometers readings could be analyzed and to find a specific pattern such as a heart
beat or motion along a spatial axis.
Accuracy- The sensors ability to determine a correct result. Not to be confused with
precision, the exactness of the sensor’s result. Such as the thermometer reads 75.001
degrees. Which is a precise value with +/- .001, but inaccurate given that the temperature
is actually 90 degrees.
CO2 sensor – A sensor for detecting carbon dioxide gas. These sensors can be infrared
gas sensors or chemical gas sensors.
Data Acquisition System (DAQ) – Data acquisition, device that is used to send data to a
computer using an external interface, usually connected to proprietary hardware.
Decibel (DB) – A Decibel is a logarithmic unit of measurement that expresses the
magnitude of a physical quantity (usually power or intensity).
Lab 1 – DFM Product Specification - 10
DFM- Don’t Forget Me, a system designed to prevent harm to humans and animals by
detecting life and high temperatures in a vehicle.
Heartbeat sensor – A sensor that detects tiny vibrations and determines if they match the
signal of a heartbeat.
Hyperthermia- The state at which the human body is no longer able to cool down
through natural processes. The effort the body takes to reduce heat only causes one’s
temperature to rise due to the advanced state heat exposure.
Interoperability – Interoperability is the ability of diverse systems to work together
(inter-operate).
Infrared (IR) – radiation is electromagnetic radiation of a wavelength longer than that of
visible light, but shorter than that of microwaves.
Key fob- An item attached to a key ring or key chain, used either for decoration or to
assist the owner in the act of authentication.
LabVIEW – Graphical development environment made by National Instruments.
Microcontroller- A microprocessor that is optimized for self-sufficient systems, usually
runs on low power, and does not require a complex set of hardware.
Motion sensor – Sensor for detecting movement or motion.
Pressure sensor – Sensor for detecting change in pressure.
Pulse Oximeter- A medical device that is used to measure oxygen saturation in one’s
bloodstream. The arterial blood vessels expand and contract with each heart beat
changing the oxygen concentration which allows the device to measure pulse rate.
Radio Frequency (RF) – Any frequency within the electromagnetic spectrum associated
with radio wave propagation. When an RF current is supplied to an antenna, an
Lab 1 – DFM Product Specification - 11
electromagnetic field is created that then is able to propagate through space. Many
wireless technologies are based on RF field propagation.
Sensor -- Any device designed to measure conditions or ambient pressures and
temperatures. A sensor is electronic in nature and designed to send a voltage signal to
computer device.
Thermistor (Temperature sensor) – A thermally sensitive resistor that produces a
difference in electrical resistance when a change in temperature occurs.
Universal service bus (USB) – USB is a serial bus standard to interface devices. USB is
intended by design to allow peripherals to be connected using a single standardized
interface socket and utilizing plug and play capabilities.
1.4 References
Department of Geosciences. (2007). Hyperthermia Deaths of Children in Vehicles.
Retrieved
January 21, 2008, from San Francisco State Unv. Web
site: http://ggweather.com/heat/.
Gonzales, Hernan (2007,December). Major Functional Component Diagram. [Figure 1]
Figure created during CS 410 at Old Dominion University.
Holloway, Daniel. (2008). Lab 1 – DFM Product Description. Gloucester, VA: Author.
Kids and Cars. Welcome to the KIDS and CARS Website! Retrieved January 21, 2008,
from Kids and Cars Web site: http://www.kidsandcars.org/.
Labview. Online NI LabVIEW 20 Years of Innovation. Retrieved February 02, 2008, from
National Instruments Web site: http://www.ni.com/labview/.
Lab 1 – DFM Product Specification - 12
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1.5 Overview
The product specification consists of the hardware and software
configuration, capabilities, and features of the DFM system prototype. The information
provided in the remaining sections of this document include a detailed description of the
hardware, software, and external interface architecture of the DFM system prototype; the
key features of the prototype; the parameters that are used to control, manage, or establish
these features; and the performance characteristics of these features in terms of inputs,
outputs, and user interaction.
2
General Description
The prototype of the DFM system demonstrates the innovative design utilizing an
array of sensors and using complex algorithms to diminish the chance of a false alarm in
detecting occupancy and unsafe conditions. The CO2 sensor is simulated in the prototype
by producing a signal to demonstrate the accuracy in determining an occupant. Finally, a
pulse oximeter is used instead of an accelerometer to detect a heartbeat.
2.1 Prototype Architecture Description
Figure 2 illustrates the major functional components of the DFM system
prototype and how the sensors interface with the DAQ. It simplifies the components
shown in Figure 1, but also provides the same innovative functionality.
Lab 1 – DFM Product Specification - 13
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Figure 2. Phase 1 prototype major functional component diagram
In the prototype, there are six signals monitored from six separate components.
The first component is a microphone that picks up noise for which a sound VI will
monitor and set a flag representing noise if a predetermined dB occurs. The second
component is a temperature sensor that steadily senses the temperature inside the
compartment. If the temperature rises above 90 º or falls below 30 º, a temperature VI
monitoring the signal sets a flag representing extreme temperature. The third component
is a pulse oximeter that is monitoring a heart beat. The pulse oximeter consists of a clip
Lab 1 – DFM Product Specification - 14
that is attached to a occupant’s finger. There is also a heartbeat VI that monitors the heart
beat received from the pulse oximeter. If a heart beat is detected, the heartbeat VI sets a
flag representing a heartbeat. A fourth component is the motion sensor. An ultrasonic
transmitter and receiver is sensing any movement more that 1 cm. If there is movement
detected a flag is set representing movement. A fifth component is the pressure sensor. A
pressure sensor is utilized to detect a person in a seated position. If the pressure is above a
certain psi, a pressure VI monitors the signal and sets a flag representing pressure. A
sixth component is a CO2 sensor. The CO2 sensor in the prototype is simulated by
producing a signal when a switch is turned on. The seventh component in the prototype is
a reset switch. The reset switch is used to turn off the key fob so an alarm is not turned on
if the key fob is out of the predefined distance. The eight component of the prototype is
DAQ. The DAQ is used to collect the data produced by the sensors connected to the
channel on the DAQ. The ninth component in the prototype is the IR transmitter and
receiver. The transmitter and receiver are used to simulate the key fob and an IR VI
monitors and detects if the signal is out of range. All of the VIs are created using
LabVIEW, which is preloaded on a personal laptop. Table 1 provides a summary of the
components used in the prototype compared to the commercial DFM system.
Lab 1 – DFM Product Specification - 15
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Features
Motion Sensor
CO2 Sensor
Pressure Sensor
Heartbeat Sensor
Real-World
The software will
analyze the values read
from the motion sensor
over time to determine if
the readings may be
influenced by a person.
An instance of motion
without life would be
the movement of the
vehicle’s air
conditioning vents.
The sensor will measure
the level of CO2 in the
vehicle. A steady
increase will indicate
there is no ventilation
and human or animal is
present.
Like the motion sensor
the values given to the
software will be used to
determine if there is not
a pattern that could
indicate life. This would
mitigate false alarms
due to devices that could
trigger the sensor, such
as a child’s mechanical
toy.
An accelerometer will
be installed that is
capable of sensing a
heartbeat through the
vehicles back seat. The
accelerometer can detect
small fluctuations in
movement, thereby
indicating a heart
rhythm. It will also be
used to monitor health
based on rhythm.
Prototype
The motion sensor will
read in several values
over a short time period.
If motion is detected
over that time period
then the software will
assert that a person is
present.
The CO2 sensor will be
simulated for the
prototype. This will be
accomplished by
creating a signal to test
algorithms.
The sensor will be
placed under a cushion
for the volunteer to
activate. By sitting he or
she will activate the
pressure sensor. This
would simulate a child
sitting in a rear or safety
seat.
A pulse oximeter will be
attached to a volunteer’s
finger. This device will
give the same input
values of the
accelerometer, but will
require the volunteer to
be attached to the device.
Likewise, the presence
of a pulse will be the
only criteria, not rhythm.
Lab 1 – DFM Product Specification - 16
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Features
Temperature Sensor
Microcontroller/CPU
Infrared Receiver and Transmitter
Alarm
Reset Switch
Real-World
The temperature sensor
will read in very precise
values to determine that
rate of temperature
change to determine
when a threat may
become imminent.
A microcontroller will
be used to implement
the software created by
the DFM development
team. The controller will
interface with all the
hardware and run the
analysis algorithms to
evaluate occupancy.
A receiver will be
placed in the car with
the generator as a key
fob. When the generator
goes out of range (20ft.)
the car’s alarm will
sound.
The alarm will be
implemented by
whatever means the car
manufacturer would
like. It is strongly
suggested that the car’s
built in horn or alarm
system be used given
the public’s familiarity
to car alarms and what
they entail.
A switch will be placed
in rear of the vehicle so
that the driver can
manually shut off the
device in case of a false
alarm.
Table 1. Feature comparison between full product and prototype
Prototype
A thermistor will read
the current temperature
of the room and indicate
when the level becomes
too dangerous for a
human.
LabVIEW development
software will be used to
implement all the logic
necessary to run the
DFM system. The
sensors are wired to a
DAQ instead of the
microprocessor.
The same
implementation will take
place, but the generator
will not be in the form of
a key fob. The infrared
used in the prototype is
limited to 8 ft.
A small speaker will be
used to generate noise
and indicate the alarm. A
car alarm will not be
necessary to
demonstrate.
A switch will be added
to the set of hardware,
but the logical
implementation will not
be as elaborate.
Lab 1 – DFM Product Specification - 17
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2.2 Prototype Functional Description
The prototype of the DFM system is designed to demonstrate how the technology
implemented in this device will contain a more accurate means for deciding that there is
an occupant left in a vehicle who needs a caregiver. In this section, the topics covered are
prototype functional objectives, prototype architecture, innovative features and
challenges and risks. The prototype will prove the validity of how the DFM system
incorporates a better solution for detecting occupancy.
2.2.1 Prototype Functional Objectives
The first functional objective is to demonstrate the use of various sensor
technologies. LabVIEW will be used to show that the sensors are detecting the
environmental conditions that they are designed for. First, a temperature sensor will show
the temperature in real time through a virtual instrument that will represent a
thermometer. Second, a motion sensor will show movement in real time through a virtual
instrument that will be represented by a light emitting diode (LED) and will only be
turned off when motion has deceased for a period of time. Third, a pressure sensor will be
utilized and represented by the use of a virtual instrument in the form of a graphical
meter. The sensor will detect small vibrations that will be compared to a predetermined
signal and aid in detecting an occupant in the vehicle. Fourth, a pulse oximeter sensor
will aid to determine life in a vehicle. The task is achieved through attaching the pulse
oximeter to an individual’s finger to detect the presence of a pulse.
Lab 1 – DFM Product Specification - 18
The second objective is to demonstrate the interoperability of the array of different
sensors utilized in this system. In order to achieve this objective, virtual instruments will
be created by using LabVIEW software. Also, algorithms will be written to receive the
signals from a vast array of sensors, and analyze the data to determine if harmful
conditions exist. Using logic, when temperature rises above 90 º F for three minutes or if
the temperature falls to 30 º F for three minutes, the DFM system will send a signal to
sound an alarm.
The third and last objective will be to demonstrate that the DFM system will provide
a more accurate means of determining if an occupant is left in a vehicle by their
caregiver, and will eliminate false alarms from occurring that can take up resources in
personnel and equipment that ultimately cost taxpayer’s money.
2.3 External Interfaces
The external interfaces in this section include hardware and software interfaces. For
hardware interfaces, the DFM prototype utilizes a DAQ, microphone, thermistor,
pressure sensor, IR transmitter and receiver, CO2 sensor, ultra sonic motion sensors,
pulse oximeter, alarm, reset switch and laptop computer. For the software interface,
LabVIEW development software is utilized.
2.3.1 Hardware Interfaces
1. Data Acquisition (NI USB-6009): The National Instruments USB-6009 is a
multifunction data acquisition (DAQ) module that provides reliable data
acquisition with an economical price tag. The DAQ provides plug-and-play USB
connectivity and capable of handling complex measurements. The DAQ has eight
Lab 1 – DFM Product Specification - 19
analog inputs, two analog outputs, and twelve digital input/output channels
(Figure 3).
Figure 3- NI 6009 DAQ
2. Thermistor: A linear thermistor sensor is used for air temperature measurement
(Figure 4). The thermistor has a plastic cage for protection but is open for air
flow. The dimensions for the thermistor are 31.8 mm in length and 13 mm in
diameter. The thermistor has three conductors consisting of one for positive
voltage, another for negitive voltage and the third for reference connection.
Figure 4- Thermistor
3. Pulse oximeter: A pulse oximeter is a medical device that measures the oxygen
saturation of one’s blood (Figure 5). The pulse oximeter measures changes in
blood volume in the skin producing a photoplethvmograph. The pulse oximiter
has a pair of small light emitting diodes (LEDs) facing a photodiode through a
part of one’s body part usually a fingertip. The pulse oximeter consists of a red
LED that has a wavelength of 660 nm. A second LED is infrared that has a
wavelength in the range of 905 to 940 nm. The ratio can be calculated from the
absorption of the red and infrared light.
Lab 1 – DFM Product Specification - 20
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Figure 5- Pulse oximeter clipped on a finger
4. Microphone: The microphone is multi-directional that can be used for a wide
variety of voice applications (Figure 6). The microphone also features noisecanceling technology that ensures clear voice transmission. The microphone has a
7 foot cord and one end stripped to connect to the DAQ. The microphone has a
sensitivity of 40 dB and impedance of 850 ohms.
Figure 6- Microphone
5. Reset button: The reset button is a single pole single throw push button switch
(SPST) that has a contact rating of 2 amps at 14 volts DC (Figure 7). The
dimensions for the reset button is .425 by .660 cm. The reset button provides the
ability to turn off the key fob in order to go outside the range of RF transmission
(ex. to pump gas).
Lab 1 – DFM Product Specification - 21
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Figure 7- Push button
6. Pressure sensor: The pressure sensor is of the MPX10 series that is a silicon
peizoresistive pressure sensor (Figure 8). The pressure sensor provides a very
accurate linear voltage output directly proportional to the applied pressure. The
manufacture is Motorolla Inc. and operates on a voltage between three and
sixVDC. The output range is between 20 and 50 mV. The pressure sensor
provides the capability to help detect an occupant by the pressure in which the
occupant in the seated position applies. There are three types of air pressure
measurement absolute, differential and gauge pressure. Absolute pressure sensors
measure and external pressure relative to a zero pressure reference point.
Differential pressure sensors measure the difference between pressures applied
simultaneously to opposite sides of the diaphragm. A positive pressure applied to
the pressure side generates a negative voltage to the vacuum side. Gauge pressure
sensors are a special type of differential sensor in which the pressure applied to
the pressure side is measured against the atmospheric pressure on the vacuum
side. For the prototype, a differential pressure sensor will be used. The sensor is
one component in a circuit containing resistors, capacitors, transistors, 5 volt
regulator and piece of Tygon tubing connected to the vacuum side where the
pressure will be applied.
Lab 1 – DFM Product Specification - 22
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Figure 8- Pressure sensor
7. Ultra sonic motion sensor: The motion sensor consists of a transmitter and
receiver. The transmitter has a bandwidth of 4 kHz at 112 dB and sound pressure
level of 119 dB at 40 kHz. The receiver has a bandwidth of 3.5 KHz at 71 dB and
a sensitivity of 65 dB at 40 kHz. Both the transmitter and receiver have a
dimension of .47 inches by .62 inches in diameter. The transmitter and receiver
are two of the electrical components soldered on a printed circuit board. The
printed circuit board layout can be seen in the below circuit diagram (Figure 9).
Figure 9. Phase 1 prototype motion sensor circuit board
Lab 1 – DFM Product Specification - 23
Sound waves reflected by moving objects arrive at the receiver in different phases. If
the signals are in phase, they are added to the current signal creating a larger signal. If
the signals are out of phase, they cancel to give a smaller signal. If a moving object
moves as small as 1 cm, the motion causes the receiver to cycle through a high/low
cycle.
8. Laptop computer: The laptop computer will have at least 1 gig of memory and a
Pentium 4 processor (Figure 10). The laptop will also need a USB port for the
DAQ to be attached. The laptop will have LabVIEW preinstalled along with the
driver for the NI 6009 DAQ driver.
Figure 10- Laptop
9. CO2 sensor: The CO2 sensor in the prototype is a simulated signal. The
simulation is activated by an on/off switch that will generate a voltage signal in
order to test the algorithm for determining occupancy.
10. Alarm: The alarm in the prototype is used to sound an alarm when an occupant is
left in the vehicle, unsafe environment conditions exist or both conditions are met.
The following list shows the conditions for the alarm.

The alarm will reset each time the car is started.

The alarm will only go on when life is detected.

The item can be switched off before the alarm goes on.

Alarm will never go off while driving.
Lab 1 – DFM Product Specification - 24

The alarm will continue to sound until it is manually reset.

If the temp is high and life exist, then the alarm cannot be reset.

If the baby is removed there will be an automatic reset.
2.3.2 Software Interfaces
1. LabVIEW 8.2 software: National Instrument LabVIEW is a graphical
development environment that provides the development of scalable test,
measurement, and control applications (Figure 11). LabVIEW provides a G
language which is a graphical programming language. LabVIEW is a solution for
event driven programming, state diagram development, and continuous time
systems. One can gather data from numerous instruments and data acquisition
devices using LabVIEW development tools. LabVIEW also provides a means for
rapid development and deployment. LabVIEW can run on Windows, MAC and
Linux operating systems.
Figure 11- National Instruments LabVIEW development environment
2. Occupancy and harmful condition algorithms:
Algorithms are written to determine occupancy in a vehicle. The signals received from
the CO2 sensor, pulse oximeter, pressure sensor, motion sensor and microphone will be
given weights in determining an occupant. The priority values are set for the accuracy of
Lab 1 – DFM Product Specification - 25
the type of signal. The values are Pulse Sensor 4, Motion Sensor 3, CO2 Sensor 3,
Pressure Sensor 2 and Microphone 1.
3
Specific Requirements
The following section describes the specific functional, performance, and non-
functional requirements of the DFM system prototype. The functional requirements
section discusses what is required in order for the prototype to function properly. The
performance requirements section discusses what performance is optimal for the success
of the prototype demonstration. The non-functional requirements section discusses what
functions are outside the scope of the prototype.
3.1 Functional Requirements
The functional requirements describe the capabilities of the DFM system
prototype. The functional requirements discuss what the product must perform in order
to meet the previously discussed objectives of the project. The functions discussed in this
section include DFM self-test, detection for occupancy, detection for unsafe conditions
and the affect of resetting system.
3.1.1 DFM system is activated and goes through self-test
The DFM system when activated runs through a self-test to verify all components
are working. Test algorithms including temperature, CO2, pressure, pulse oximeter,
motion, alarm and microphone exist to check for hardware failure of the components.
First, the pulse sensor is sent a signal and if it responds, a Boolean value of true is
Lab 1 – DFM Product Specification - 26
returned. Second, a signal is sent to the motion sensor and if a response is received a
Boolean value of true is set. Third, a signal is sent to the temperature sensor and a
Boolean value of true is set if a response is made. Fourth, a signal is sent to the CO2
sensor and a Boolean value is returned simulating a response. Fifth, a signal is sent to the
pressure sensor and a Boolean value of true is set upon receiving a response. Sixth, a
signal is sent to a microphone and if a response is received a Boolean value of true is set.
If any test function causes a non-response event, a Boolean value of false is set. Seventh,
a signal is sent to the alarm to see if the alarm goes off. A Boolean value is set to true if
the alarm goes off. Upon completion of test functions if any Boolean variables are false, a
warning light is turned on. Figure 12 shows the flow of the test algorithms.
Lab 1 – DFM Product Specification - 27
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Figure 12. Phase 1 prototype test algorithm
3.1.2 Detecting occupancy
Detection of occupancy requires the utilization of the CO2 sensor, pulse oximeter
sensor, motion sensor, pressure sensor and microphone. The sensors are part of the detect
occupant function shown in figure 13. The sensors are given weight values in order to
accurately determine occupancy yet not ruling out an occupant if a sensor in the array
does not send a high value. The priority values are pulse sensor equals four, motion
sensor equals three, CO2 sensor equals three, pressure sensor equals two and microphone
Lab 1 – DFM Product Specification - 28
equals one. A return value must be greater than five in order for an occupant to be
determined. The value of greater than five will ensure at least two sensors have detected
an occupant unless the microphone is one of the sensors. The low value for the
microphone is given because noise can be generated outside the vehicle compartment.
Figure 13 show the flow for the major life detection algorithms.
Figure 13. Phase 1 prototype major life detection algorithm
Lab 1 – DFM Product Specification - 29
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3.1.3 Detecting unsafe conditions
Detection of unsafe conditions is acquired through the use of a temperature sensor. The
temperature sensor will detect the temperature from within the compartment of the car.
The assumption is the occupant is dressed for average room temperature similar to 70 º F.
If a value of 90 º F or higher has been detected, a signal representing an unsafe condition
has been met. In the same respect, value of 30 º F or less will also send a signal
representing an unsafe condition has been met. The alarm will go off if any one of these
conditions is met.
3.1.4 Resetting the DFM system
The DFM system can be reset where the key fob will be deactivated so the care giver can
go out of the 20 feet range with out triggering the alarm. The alarm will reset each time
the car is started. The alarm will only go on when life is detected. The item can be
switched off before the alarm goes on. Also, the alarm will never go off while driving. If
the alarm is triggered, the alarm will continue to sound until it is manually reset. If the
temperature is high and occupancy is detected, then the alarm cannot be reset.
Furthermore, if the baby is removed there will be an automatic reset of the system.
Figure 14 shows the detail flow of decision-making for the DFM system.
Lab 1 – DFM Product Specification - 30
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Figure 14- Phase 1 prototype detail detection algorithm
3.2 Performance Requirements
The following performance requirements describe how well the functions of the
DFM system prototype shall be executed in terms that are measurable. These
requirements each correspond to the functional requirements, and provide measurable
goals for validating an occupant or unsafe condition. The test cases verify that the
components are not only working but also working properly.
Lab 1 – DFM Product Specification - 31
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3.2.1 Test algorithms
The test algorithms shall meet the following performance requirements:
1) Test all components to verify hardware is operating
2) The test cycle should take less than 30 seconds to ensure test are complete before
car is driven.
3) If any hardware is not functioning, a light must be displayed.
3.2.2 Occupancy detection
The occupancy detection algorithms shall meet the following performance
requirements:
1. Alarm is triggered upon a value greater than 5 is returned from occupancy
detection algorithms.
2. Alarm is sounded within 2 seconds upon detection.
3.2.3 Unsafe conditions detection
The authentication manager shall meet the following performance requirements:
1. Alarm is triggered upon receiving a detection of a temperature greater than or
equal to 90 º F.
2. Alarm is triggered upon receiving a detection of a temperature lower or equal to
30 º F.
3. The alarm must be sounded instantaneous to detecting an unsafe condition.
Lab 1 – DFM Product Specification - 32
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3.2.4 Resetting the DFM system
The resetting of the DFM system shall meet the following performance
requirements:
1. When the DFM reset button is activated, the key fob is deactivated until
system is restarted.
2. The key fob should instantaneously be deactivated upon reset button
activated.
3. The other components should still be in an activated state.
Lab 1 – DFM Product Specification - 33
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3.3 Assumptions and Constraints
Table 2 contains the full list of assumptions, constraints, and dependencies for the
DFM system prototype. The assumptions and constraints show the events or values that
are assumed in the demonstration of the DFM. The second column shows whether it is an
assumption or constraint. The third column shows the effect from the assumption or
constraint.
Condition
Type
30° F is the “cool” temperature at
which point alarm goes off.
Assumption
90° F is the “hot” temperature at
which point alarm goes off.
Assumption
Detection of pressure indicates
detection of occupant.
Assumption
Occupant has no remarkable
medical conditions.
Occupant is appropriately dressed
for the weather.
Reset switch is not used
accidentally or maliciously.
CO2 sensor is not incorporated
into prototype.
Heartbeat is detected by pulse
oximeter.
Prediction of extreme
temperatures is not supported.
All sensors function properly at
time of demonstration.
PC or laptop with LabVIEW
installed is available at time of
demonstration.
Assumption
Assumption
Assumption
Constraint
Constraint
Constraint
Dependency
Dependency
Effect On Requirements
Cooling device must be present at
demonstration to lower
temperature.
Heating device must be present at
demonstration to raise
temperature.
Prototype distinguishes between
pressure and no pressure; not
between different pressures.
Medical conditions may affect
input from pulse oximeter.
Varied clothing affects
effectiveness of the system.
Accidental or malicious use of
the reset switch defeats the
purpose of the system.
Input from CO2 sensor is
simulated by the software.
Pulse oximeter must be attached
to occupant’s finger.
Alarm is only activated if an
extreme temperature is detected.
Prototype cannot be demonstrated
without input from the sensors.
Prototype cannot be demonstrated
without the LabVIEW software
Table 2- Assumptions and Constraints table for the DFM system prototype
3.3.1 Assumptions
Six assumptions are being made. First, the low temperature threshold is 30 º F in
which the alarm will go off. The second assumption is the high temperature for which
the alarm goes off is 90 º F. The third assumption is the detection of pressure means an
Lab 1 – DFM Product Specification - 34
occupant exist. The fourth assumption is that the occupant does not have a medical
condition in which the normal conditions might not pertain to the individual. The fifth
assumption is that the occupant is dressed for normal conditions. Normal means the
temperature in the compartment is similar to room temperature. The sixth assumption is
that the reset switch is not accidentally turned on. The reset switch could be accidentally
set by an occupant that would mean the key fob will not receive an alarm and the car
alarm will not go off if the key fob has a displacement beyond 20 feet.
3.3.2 Constraints
The constraints are in place because of budget limitations. The first constraint is that
the CO2 sensor is simulated by a generated signal. The generated signal is created when a
switch is turned on in order to demonstrate the precision of determining an occupant.
The second constraint is a heartbeat is detected by a pulse oximeter instead of an
accelerometer. The pulse oximeter is attached to an individual in order to detect a
heartbeat. The third constraint is the value of extreme temperatures is not supported.
3.3.3 Dependency
The first dependency is that all of the sensors function properly at the time of the
demonstration. If any of the sensors fail at the time of the prototype demo, there will be a
perception of the system does not work properly. The second dependency is that a laptop
is available and LabVIEW is installed on the laptop. Two laptops will be available with
LabVIEW install to diminish the risk of the graphical software not working correctly
during the demonstration of the prototype.
Lab 1 – DFM Product Specification - 35
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3.4 Non-Functional Requirements
Non-functional requirements address features of the prototype that are outside of
the main innovative functionality.
3.4.1 Maintainability
The system is setup prior to the demonstration and verification shall be made on
all components. There is an extra part to every component needed for demonstration of
the prototype. All wiring harnesses shall be labeled per wire for fast trouble shooting
upon any failure. Also, all wires shall be enclosed and not exposed. There will be an extra
laptop with LabVIEW installed in case of computer issues.
3.4.2 Reliability
The DFM system prototype must perform 100 % accuracy of detection of an
occupant and determining an unsafe condition is met. The test algorithms, occupancy
algorithms and unsafe condition algorithms are tested and retested to verify 100%
accuracy.
4 Appendix
The appendix contains additional documentation for the DFM system prototype.
The document in the appendix is the resource request document. Other document can be
added as needed. The request document is shown in detain in the following section.
Lab 1 – DFM Product Specification - 36
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4.1 Appendix
Formal Resource Request Document
Team: Don’t Forget Me Inc.
Project Manager: Brandon Fields
The following resources are required to be purchased for the prototype development and
demonstration of the XYZ product:
Hardware Purchase (list all items required for purchase):
Part Description
Sensor, Ultrasonic, 40Khz, Tran
Sensor, Pressure, 0-1.45 PSI
Kit, Infrared Tran and Rec
Linerar Thermistor Air Temperature
Pulse Oximeter
http://www.fitness-equipment.com/acatalog/
Online_Catalog_Pulse_Monitor__Ear_Clip_
for_Pulse_Monitor_1034.html
USB-6009 Kit (LabVIEW and DAQ)
Part #
136654
218827
177092
OL-706
Company
Jameco.com
Jameco.com
Jameco.com
Omega.com
P-703A
779320-22
FitnessEquipment
NI.com
Qty Price Ea
2
$7.95
2
$8.99
2
$24.95
1
$61.00
2
2
$19.99
$159.00
Total
$15.90
$19.98
$49.90
$68.00
$39.98
$331.62
Software Purchase (list all items required for purchase):
Part Description
FRAPS - Real-time video render
software
Part #
Company
N/A
Fraps.com
Qty
Price Ea Total
1
$37.00
The following University resources are required to support the prototype development
and demonstration:
1. Laptop/ Second computer
a. It will be used to display the interaction of hardware element and
the algorithm processes during the live prototype demonstration.
b. Windows XP with connection to the internet
c. Quantity: 1
d. Date required: March 1, 2008
e. Deliver to: Don’t Forget Me Inc.
2. LabVIEW installed on the Laptop
a. LabVIEW is the primary software component used in the project.
Through it the development team will interact with the hardware
and control the system algorithms.
b. LabVIEW must have the drivers installed for the DAQ used in the
prototype, a USB-6009.
c. Quantity 1
d. Date required: March 1, 2008
e. Deliver to: Don’t Forget Me Inc.
$37.00