Lab 2 – Don’t Forget Me: Product Description
Brandon Fields
CS411
Janet Brunelle
April 9, 2008
Lab 2 – Don’t Forget Me
Table of Contents
1
Introduction ................................................................................................................. 1
1.1
Purpose................................................................................................................ 2
1.2
Scope ................................................................................................................... 4
1.3
Definitions, Acronyms, and Abbreviations ........................................................ 5
1.4
References ........................................................................................................... 8
1.5
Overview ............................................................................................................. 8
2 General Description .................................................................................................... 9
2.1
Prototype Architecture Description .................................................................... 9
2.2
Prototype Functional Description ..................................................................... 12
2.3
External Interfaces ............................................................................................ 17
2.3.1
Hardware Interfaces .................................................................................. 17
2.3.2
Software Interfaces ................................................................................... 18
2.3.3
User Interfaces .......................................................................................... 20
2.3.4
Communication Protocols and Interfaces ................................................. 21
3 SPECIFIC REQUIREMENTS.................................................................................. 21
3.1
Functional Requirements .................................................................................. 21
3.1.1
DFM System Activation Process .............................................................. 21
3.1.1.1 Sensor Overview ................................................................................... 22
3.1.1.2 Life Detection Sensors .......................................................................... 22
3.1.1.3 Environmental Sensor ........................................................................... 23
3.1.2
Life Detection Procedures......................................................................... 23
3.1.3
Environment Evaluation Procedures......................................................... 24
3.1.4
Transmitter and Receiver Functions ......................................................... 24
3.1.5
Alarm System............................................................................................ 25
3.1.6
Reset Procedures ....................................................................................... 26
3.1.7
LabVIEW Setup ........................................................................................ 26
3.1.8
Simulation Procedures .............................................................................. 27
3.2
Performance Requirements ............................................................................... 27
3.2.1
DFM System Activation ........................................................................... 27
3.2.2
Life Detection ........................................................................................... 28
3.2.2.1 Sensor Performance .............................................................................. 28
3.2.2.2 Procedure Performance ......................................................................... 29
3.2.3
Environmental ........................................................................................... 29
3.2.3.1 Sensor Performance .............................................................................. 29
3.2.3.2 Procedure Performance ......................................................................... 30
3.2.4
Transmitter and Receiver Functions ......................................................... 30
3.3
Assumptions and Constraints ............................................................................ 31
3.3.1
Assumptions.............................................................................................. 32
3.3.2
Constraints ................................................................................................ 33
3.3.3
Dependencies ............................................................................................ 35
3.4
Non-Functional Requirements .......................................................................... 35
3.4.1
Security ..................................................................................................... 35
3.4.2
Maintainability .......................................................................................... 36
3.4.3
Reliability.................................................................................................. 36
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4
APPENDIX ............................................................................................................... 37
List of Figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Major Functional Component Diagram ............................................................. 2
Prototype Major Functional Component Diagram........................................... 10
DFM Algorithm Flowchart ............................................................................. 13
DFM Activation Flowchart ............................................................................. 15
DFM Life Detection Algorithm ...................................................................... 16
Environmenal Sensor ...................................................................................... 17
Life Detection Sensors .................................................................................... 18
Alarm VI Front Panel display ......................................................................... 19
Alarm VI Block Diagram ................................................................................ 20
List of Tables
Table 1. Sensor priorities .................................................................................................... 3
Table 2. Feature comparison between full product and prototype.................................... 12
Table 3. Effects of Assumptions, Dependencies, and Constraints on Requirements ....... 32
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1 Introduction
Last year, at least 43 children died in cars while their parent or caregiver was
away, and each year the number of related deaths increases (KAC, 2007). Unfortunately,
it does not take long for a car to become dangerously hot and endanger the life of a child
inside. Currently, passenger vehicles do not have the capability to determine when the
conditions of its interior pose a danger to its occupants, nor do vehicles have the ability to
register that a child has been left inside.
The goal of the Don't Forget Me (DFM) system is to eliminate such instances of
intentional or unintentional child endangerment. By installing a series of sensors along
with software that determine if a vehicle is occupied, the system can immediately take
corrective action. A heartbeat sensing system is one of the primary components; the data
it collects is analyzed for a verifiable pattern. Secondly, pressure sensors installed
beneath the seats determine if anyone is occupying the vehicle. Once again, the outputs
of the sensors are checked by the accompanying software to ensure it is a person and not
an obstruction that is detected. A microphone is implemented to monitor for loud noises
which will help determine if the vehicle is occupied. Temperature, motion, and CO2 are
also constantly monitored inside the car. Since the temperature can rise to fatal levels in
minutes, a high temperature reading initiates an aggressive check of the vehicle for
people in danger.
When inputs from all the sensors collectively indicate that the vehicle is occupied,
the vehicle’s alarm system is initiated. Also, the driver’s key fob attachment will begin
to vibrate to indicate that the alarm system has been activated. This device is
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autonomous and does not require the activation of the car's operator. It seeks to eliminate
instances when one can let even important issues pass their attention (Fields, 2008).
1.1 Purpose
The DFM safety system is unique because it utilizes an assortment of sensors to
detect life in a manner that has never before been implemented. While two or more
sensors may be sufficient to detect life, more would be necessary to reach a high degree
of certainty. Each sensor allows the software to incorporate a system of checks and
balances to prevent false alarms or decisions made from insufficient data. Likewise, the
system will not be rendered useless when one sensor inevitably malfunctions, given the
lifespan of any component in a vehicle over an extended period of time.
Figure 1. Major Functional Component Diagram
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Overall, the greatest strength of the DFM system is the software developed to
integrate each hardware component into one homogenous system, as depicted in the
Figure 1. Under the assumption that no two types of sensors have the same accuracy,
neither will they have the same priority. While a motion sensor is effective at detecting
movement, it would not have the same accuracy as a heartbeat sensor meant to analyze a
heart’s rhythm; therefore, it is prudent to grant a positive reading from the heartbeat
sensor higher priority than the result from a motion sensor. A CO2 sensor is even less
indicative of life given that the car is not airtight and the sensor may have a low level of
precision. As a result, the DFM system must take each of the sensors’ results into a
priority based system where each sensor is capable of generating a positive result for life
detection independently of the others.
Life Detection Sensors
Priority Value
Pulse Sensor
4
Motion Sensor
3
CO2 Sensor
3
Pressure Sensor
2
Microphone
1
Table 1. Sensor priorities
Table 1 indicates the specific priorities for the DFM system. In order for life to
be detected with a high level of certainty, the sum of the values must be greater than five.
The specific values were designated based on the combination of sensors that would be
needed to give a positive reading for the alarm to be initiated. For example, the pulse
sensor and any of the three beneath it in the table will cause the alarm to go off.
Likewise, the CO2 and the pressure sensor would not be high enough in priority to initiate
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the alarm, but if the microphone was also getting a positive reading, the system would
acknowledge the presence of life.
The process of prioritizing the sensors’ results allows the DFM system to
correctly indicate the presence of life even if some of the sensors are generating false
results. In the same manner that shareholders have proportional control of a company,
each sensor will have a degree of influence over the system, which is determined by its
accuracy. The software will take into account the different values of influence and
certainty generated by sensor data and make an educated decision whether to act (Fields,
2008).
1.2 Scope
The objectives of the prototype are to show that the DFM system can in fact
determine if a human life is present, if the environment has become hazardous, and if the
driver is close enough to provide assistance. The sensors can test if a human is present by
providing data to the LabVIEW (Laboratory Virtual Instrumentation Engineering
Workbench) software where each sensor can independently evaluate conditions inside of
the vehicle. If the certainty is high over the majority of the sensors, a life will be
assumed present. Life detection can be tested by setting off each sensor alone or in
different combinations to determine if the algorithm is effective and appropriate alarms
are activated.
Next, the environment is deemed hazardous if the temperature is rising or falling
at a rate that would become harmful. Not only is the current temperature taken into
account, but also the past temperatures. This way, the DFM system can set off the alarm
even if danger is still minutes away. The system would be very ineffective if it sounds an
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alarm only when the environment is deadly, or even if the driver is too far gone to
ameliorate the situation.
Lastly, the prototype shows that a driver’s distance from the car is being
monitored by the DFM system. If the driver goes further than 20ft from the car, the
alarm will sound regardless of the temperature in the car. Likewise, despite the driver’s
distance from the car, the alarm will sound if the temperature or other conditions reached
a fatal level. What is most important is any person or child left in the car when the alarm
sounds is removed before the system is reset, which is why the reset is positioned in the
rear center of the vehicle (Fields, 2008).
1.3 Definitions, Acronyms, and Abbreviations
This section provides definitions and further explanations for terms used in the
document. If a term uses an acronym, it is spelled out in this section. This section is
meant to assist the reader in understanding the terminology used in this document.
Accelerometer: A device that measures the force on a sensor, primarily vibrations.
Variations in the accelerometers readings could be analyzed and 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.
Algorithm: A series of finite instructions that are given a particular order.
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CO2: Carbon Dioxide, chemical combination for air that is exhaled. The change in the
air composition from low to high levels of carbon dioxide may indicate human
respiration. These sensors can be infrared gas sensors or chemical gas sensors.
CPU: Central Processing Unit, the device inside of a computer that executes machine
code (runs programs).
DAQ: National Instruments USB-6008 or USB-6009 Data Acquisition Device, a device
that is used to send data to a computer using an external interface, usually
connected to proprietary hardware.
DFM: Don’t Forget Me, a system designed to prevent harm to humans and animals by
detecting life and high temperatures in a vehicle.
GUI: Stands for Graphical User Interface. A display on a computer that uses graphics to
display content and can allow user manipulation.
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).
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: Laboratory Virtual Instrumentation Engineering Workbench, platform and
development environment for a visual programming language created by National
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Instruments. A graphical programming tool allowing for the display and
acquisition of data from a great deal of devices including external hardware.
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. This sensor could use radio
frequency or changes in light to detect motion.
Pressure sensor: Sensor for detecting change in pressure.
Proprietary Hardware: A device that is designed for specific purpose and lacks generic
qualities that would allow it to be used outside of its original implementation.
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
electromagnetic field is created that then is able to propagate through space. Many
wireless technologies are based on RF field propagation.
Respiration: Breathing in order to bring oxygen to the bloodstream and remove carbon
dioxide. The act of respiration reduces the amount of oxygen and increases the
amount of carbon dioxide enriched.
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.
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Thermistor (Temperature sensor): A thermally sensitive resistor that produces a
difference in electrical resistance when a change in temperature occurs.
Universal Serial 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.
Virtual instrument (VI): Is an object that represents an instrument which contains the
behaviors for which the instrument produces. A VI can be designed using
Labview software that utilizes G code. By programming the input and output
criteria as well as the logic of a LabVIEW file a virtual instrument can be created.
1.4 References
Fields, Brandon. (2008). Lab 1 – DFM Product Description. Norfolk, VA: Author.
Kids and Cars. (n.d.). Kids and Cars. Retrieved January 28, 2007, from Kids and Cars
Web site: http://www.kidsandcars.org/.
Oximity. (2002). Principles of Pulse Oximetry Technology. Retrieved January 21, 2007,
from Internet World Stats Web site:
http://www.oximetry.org/pulseox/principles.htm.
1.5 Overview
This product specification provides details concerning the hardware and software
design, external interfaces, and the capabilities and features of the DFM system
prototype. The following information describes the implementation of the prototype as
well as aspects of its design and considerations made during testing and demonstration.
Material covered in this document primarily pertains to the prototype of the DFM system.
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2 General Description
The DFM system is innovative in its use of simple sensors and the integration of
microcontroller technology in order to add a greater level of safety to modern
automobiles. The greatest strength of the DFM system is the algorithm that prioritizes
each of the sensors in order to determine the likelihood of life and danger. The system
intelligently decides when to act and when danger is not present. Most importantly it
seldom requires any direct interaction with the driver.
2.1 Prototype Architecture Description
The physical architecture of the prototype is focused around the LabVIEW
simulation software. LabVIEW makes it possible to interact with an array of sensors by
wiring them into the data acquisition device (DAQ). Once properly wired, the LabVIEW
software can be used interact with the ports on the DAQ. The LabVIEW software and the
laptop take the place of the CPU. Using LabVIEW removes the difficult task of creating
the physical implementation of the DFM system from their constituent components alone.
Likewise, the algorithm can be programmed and tested without wasting time and money
programming into a microcontroller.
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Figure 2. Prototype Major Functional Component Diagram
Figure 2 illustrates the major functional components of the DFM system
prototype and the interaction of its components. Table 1 elaborates on the reductions that
will take place in order to complete the prototype. Unlike the real-world implementation
of the DFM system, there will be no microcontroller for the system to be installed on;
rather, all of the software will be run through LabVIEW. While the microcontroller
would allow the DFM system to run without a dedicated computer, it would not be
flexible enough to create a very low scale prototype. Likewise, using a microcontroller
rather than simulation software would make it more difficult to test each component in
the DFM system.
(This space intentionally left blank.)
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Features
Heartbeat Sensing
Real World Project
Prototype
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.
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 attach
the device. Likewise, the presence
of a pulse will be the only criteria,
not rhythm.
CO2 Sensor
The sensor will measure the level of CO2 No CO2 sensor will be used for the
in the vehicle. A steady increase will
prototype; rather, the sensor will be
indicate there is no ventilation and
simulated in LabVIEW.
human or animal is present.
Temperature Sensor The temperature sensor will read in very A temperature sensor will read the
precise values to determine the rate of
current temperature of the room
temperature change to determine when a and indicate when the level
threat may become imminent.
becomes too dangerous for a
human.
Motion Sensor
The software will analyze the values read The motion sensor will read in
from the motion sensor over time to
several values over a short time
determine if the readings may be
period. If motion is detected over
influenced by a person. An instance of that time period, then the software
motion without life would be the
will assert that a person is present.
movement of the vehicle’s air
conditioning vents.
Pressure Sensor
Like the motion sensor the values given The sensor will be placed under a
to the software will be used to determine cushion for the volunteer to sit on.
if there is not a pattern that could indicate By sitting he or she will activate
life. Determining a pattern would
the pressure sensor, which would
mitigate false alarms due to devices that simulate a child sitting in a rear or
could trigger the sensor, such as a child’s safety seat.
mechanical toy.
Microcontroller/CPU A microcontroller will be used to
Labview simulation software will
implement the software created by the
be run in order to implement all the
DFM development team. The controller logic necessary to run the DFM
will interface with all the hardware and system. Rather than have the
run the analysis algorithms to evaluate sensors wired into a
the state of possible passengers.
microcontroller, they will interface
with the underlying software using
an input/output device known as a
DAQ.
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Features
Real World Project
Reset Switch
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. The switch will time out if the
system still indicates danger and when
the car is restarted.
Radio Frequency
A receiver will be placed in the car with
Reciever/Generator the generator as a key fob. When the
(Key Fob)
generator goes out of range (20ft.), the
car’s alarm will sound.
Alarm
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.
Microphone
A simple microphone will be integrated
into the DFM system at the middle rear
section of the vehicle behind the seat.
The microphone will merely check the
intensity of noise in the vehicle. In the
event that the noise is above a predefined
decibel level, the microphone will
indicate life.
Prototype
A switch will be added to the set of
hardware, but the logical
implementation will not be as
elaborate.
The same implementation will take
place, but the generator will not be
in the form of a key fob.
A small speaker will be used to
generate noise and indicate the
alarm. A car alarm will not be
necessary to demonstrate.
The computer's microphone will be
used in LabVIEW to determine if
the decibel level has reached a
predefined level.
Table 2. Feature comparison between full product and prototype
2.2 Prototype Functional Description
The prototype will be implemented with the USB-6008 Data Acquisition (DAQ)
device and the LabVIEW software. The DAQ will make it possible to attach several
sensors to a laptop and pass their input values to an application. The LabVIEW software
will take the values from the sensors and allow them be integrated in a visual
programming interface. As a result, logic can be built around the different values the
sensors return.
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Figure 3. DFM Algorithm Flowchart
The logic that the DFM system will use has been illustrated in Figure 3. The
sections that have dotted lines around them have been elaborated on in separate
flowcharts. The DFM system will always run, but will not be active while the car is
turned on. The decision to make the DFM system work only while the car is off is for
safety. If the alarm system were to come on while someone is driving for any reason, the
system could in fact endanger one’s life. Each hour, the DFM system will undergo the
activation process one time as depicted in Figure 4. The system will then check to see if
the car is off before going any further.
When the car is turned off, the first thing the system does is check for the reset
preempt. The alarm will go off if an occupant is present and the key fob is not detected,
but the temperature is still safe. It will also go off if an occupant is detected and the
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temperature is unsafe regardless of the preempt status. If someone wants to leave a
person in the vehicle who is capable of leaving, and the temperature is not dangerous,
they may do so without the alarm system activating if they press the reset switch before
the alarm goes off. When the temperature is safe, the reset switch is used to prevent the
alarm from activating and is referred to as a “preempt.”
After the preempt status is checked the system checks the temperature in the
vehicle. If the temperature is greater than 90 degrees Fahrenheit, or less than 30 degrees
Fahrenheit, the temperature status will be indicated as dangerous. Next, the Life
Detection Algorithm depicted in Figure 5 runs to determine if there is an occupant in the
vehicle. In the event that the temperature is dangerous and someone is in the vehicle, the
alarm system will immediately be activated.
In the event that the temperature is not dangerous but life is detected, the DFM
system will check if the key fob is in range. The range of the key fob is 20ft and should
be attached to the driver’s keys. If the key fob is not detected and an occupant is present,
the DFM system will check the preempt set value. If the preempt is not set, the alarm
system will be activated and will not stop until someone presses the reset switch. The
reset switch will then restart the system and deactivate the alarm.
(This space intentionally left blank.)
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Figure 4. DFM Activation Flowchart
Figure 4 elaborates on the activation process. The activation process is necessary
to continually test each of the sensors in the DFM system so the driver will be aware that
the system is not fully active and requires maintenance. The activation process starts
with each of the sensors sending a small amount of data to be tested. If the data is within
a reasonable range for that particular sensor and the data packet arrived in less than one
second, the sensor is validated. If any of the sensors fail validation the error value is
returned and an error light will be lit for the driver to see. The DFM system will still try
to run if the error is isolated to one of the sensors, but will not run if the error is more
severe.
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Figure 5. DFM Life Detection Algorithm
Figure 5. elaborates on the process the DFM system uses to determine if life is
present in the vehicle. Each sensor has a range of values that when returned indicate that
life has been detected by that particular sensor. After the sensor returns, a value the value
is checked to determine if that sensor detected life. If the sensor indicates that it detected
life, a value based on the priority of the sensor is added to a detection variable. If the
variable’s value is greater than five then the algorithm has determined that life is present.
(This space intentionally left blank.)
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2.3 External Interfaces
The external interfaces section describes the different ways one may interact with
the DFM system.
2.3.1 Hardware Interfaces
The development team will use each of the sensors to supply data to the
LabVIEW software with the DAQ USB-6008. A switch will be used to disable or
preempt the alarm, and a Bluetooth device will work as a key fob to indicate the driver’s
location. There will be minimal interaction with the sensors since the fully implemented
version is not meant to interface with vehicle occupants.
Figure 6. Environmenal Sensor
The environmental sensor, which is the temperature sensor depicted in Figure 6,
will be manipulated so that the system detects extreme hot and cold readings. The
environmental sensor will sit inside the vehicle in order to read the temperatures a human
might experience. The particular sensor is designed for high precision readings and is
known as a thermistor.
(This space intentionally left blank.)
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Figure 7. Life Detection Sensors
The motion sensor, pressure sensor, CO2 sensor, and microphone will all gather data
without human interaction. These sensors are collectively referred to as the Life
Detection Sensors as depicted in Figure 7. The only hardware that should ever directly
be interacted with is the key fob and reset switch.
2.3.2 Software Interfaces
The development team interfaces with the DFM system’s software through
LabVIEW. In LabVIEW, a VI (virtual instrument) is created to represent each piece of
hardware in the system. The virtual instrument allows the development team to define
the inputs, outputs, and underlying logic behind each sensor. The virtual instruments are
then integrated into the DFM system in the same manner the hardware will be installed in
the final product. The “Front Panel” is the visual interface with the virtual instrument.
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Figure 8. Alarm VI Front Panel display
For example, in Figure 8 the Alarm VI is shown. The alarm takes the sound file,
and the two switches state “Activate Alarm”, and “Stop Loop”, as input values, and
outputs sound to the computer speakers. The underlying logic for the alarm is displayed
in Figure 9, which is referred to as a “Block Diagram.” The block diagram is also
composed of VIs; this makes it a simple program since all one needs to know is the type
of input values the VI expects, the operation the VI performs, and the type of outputs the
VI will return. The entire DFM system will be programmed with this method, with each
of the sensor’s values streaming in as VI inputs.
(Space intentionally left blank.)
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Figure 9. Alarm VI Block Diagram
2.3.3 User Interfaces
The DFM system interfaces with the user exclusively through LabVIEW or the
reset switch. Through LabVIEW, which can be controlled through the keyboard of a PC,
one will be able to activate and deactivate the DFM system. At the point of activation, the
DFM system will conduct a sequence of tests to ensure that all sensors are giving valid
data. Following the activation, the life detection sequence will run until the system is
deactivated through LabVIEW or until the alarm goes off. A user may preempt the alarm
or deactivate the alarm by pressing the reset switch. In the event of an error, a message
will be displayed to the user.
(This space intentionally left blank.)
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2.3.4 Communication Protocols and Interfaces
No specific protocol will be used in the DFM system. The driver will have access
to a key fob that will transmit a radio frequency to the DFM system remotely. When the
signal no longer reaches the vehicle, the DFM system will know that the driver is out of
range.
3
SPECIFIC REQUIREMENTS
The following information provides specific information about the prototype.
Functional requirements, performance requirements, assumptions and constraints, and
non functional requirements will all be covered in this section. It is broke down into
subcategories for more precise details.
3.1 Functional Requirements
The functional requirements describe the capabilities of the DFM system
prototype. They describe what the product must do in order to meet the previously
discussed goals and objectives of the project. All graphical requirements are to be
completed using the LabVIEW application. The following requirements will ensure that
the prototype effectively completes all performance goals required to successfully
represent the completed product.
3.1.1 DFM System Activation Process
The system activation process runs each time the vehicle is shut off. It checks
each of the sensors and prepares the DFM system to run the main algorithm. Once the
system is activated, the main algorithm [Figure 3] will begin facilitating life detection.
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The procedures included in the subsections below must occur for the DFM system to be
activated.
3.1.1.1 Sensor Overview
Data is received from each of the sensors, which may use to evaluate its
performance. Each of the sensors is capable of operating independently from one
another. All of the sensors used in the prototype will comply with the following
requirements.
1.) Each sensor must read in data independently.
2.) Each sensor will display this data to the screen in an easy-to-read view.
3.1.1.2 Life Detection Sensors
The Life Detection Sensors [Figure 7] are the sensors responsible for the
detection of an occupant inside the vehicle. These sensors work together, as defined in
the Life Detection Algorithm [Figure 5]. The sensors will meet the following functional
requirements.
1.) The Life Detection Sensors will return their assigned priority values or a value of
zero. If a sensor returns a value of zero, then it means no life is detected by this sensor;
however, if a sensor returns its assigned priority value, then it means life is detected by
each sensor.
2.) The pulse sensor will determine pulse rhythm in the finger. It will not produce
pulse rhythmic data when it is attached to non-living things.
3.) The motion sensor will return a positive value when an object has a displacement
of one inch.
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4.) The pressure sensor will increase the output value when pressure is applied;
otherwise, the reading should be at its initial stage.
5.) The microphone will determine any sounds in the environment; otherwise, the
reading should be at its initial stage.
6.) The simulated CO2 sensor will determine life using its predefined value.
3.1.1.3 Environmental Sensor
The Environmental Sensors [Figure 6] are responsible for determining the status
of the surrounding environment. These sensors will detect if an occupant could be in
danger. The sensors will meet the following functional requirements.
1.) The temperature detector must detect the surrounding temperature within the
accuracy of .5 °F.
2.) If the temperature sensor records a temperature of less than 30 °F or more than 90
°F, then the algorithm activates the DFM alarm system.
3.1.2 Life Detection Procedures
This process polls each of the sensors for positive values concerning life
detection. If a value returned indicates life then an accumulator has a specified value
added to it [Table 1]. The life detection procedures will meet the following functional
requirements.
1.) The DFM system will check each of the sensors for the values that indicate life
[Figure 5].
2.) If the sensor has a value or change in data that indicates life, then the detection
value associated with that sensor should be added to the accumulation variable.
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Lab 2 – Don’t Forget Me
3.) If the accumulation variable has a value greater than five, then the life detection
process indicates a positive result.
4.) If the result of the life detection process is negative, then the process will run
again with entirely new data.
3.1.3 Environment Evaluation Procedures
The environmental evaluation procedures will evaluate if the conditions are
unsafe based upon the environmental sensors. The values determined by the
environmental sensor will be generated by a thermistor, also known as a temperature
sensor. The procedures will meet the following functional requirements.
1.) The temperature sensor will detect the temperature from inside of the vehicle.
2.) If the Life Detection Sensors detect life and the Environmental Sensors determine
unsafe conditions, then the DFM alarm system will be activated.
3.1.4 Transmitter and Receiver Functions
The receiver and transmitter will determine the driver's distance from the vehicle.
Once the driver is too far away the DFM system will assume that the child was forgotten
and in serious danger. Functionality involving the transmitter will be implemented with a
Bluetooth enabled device, while the receiver will be a Bluetooth adaptor connected to the
laptop. The transmitter and receiver will meet the following functional requirements.
1.) The transmitter will keep sending a signal to the receiver.
2.) The receiver will detect the transmitter within its perimeter range.
3.) The receiver will light up when the transmitter is detected.
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3.1.5 Alarm System
The alarm will be implemented with a sound file played over the speakers of
laptop the DFM system prototype is using. An alarm allows the DFM system to get the
attention of the driver or bystanders near the vehicle. By effectively alerting the public,
the alarm system will facilitate early action and communicate the overall severity of the
situation to people nearby. The alarm system will meet the following functional
requirements.
1.) The DFM activation process has been completed and indicates the system is
working.
2.) The state of the ignition is off.
3.) The reset switch is checked to determine if one has selected to preempt the alarm.
4.) The Environmental Sensor indicates an unsafe temperature value before the alarm
system can be activated.
5.) The life detection procedure runs. If the value received is greater than five, then
an occupant has been verified.
6.) The temperature must be extreme and an occupant must be detected before the
alarm system will activate.
7.) If the temperature is not extreme, the receiver must be out of range and an
occupant must be detected for the alarm system to activate.
8.) The alarm system is deactivated and the system is reset, if the reset switch is
pressed.
9.) The system continues to check for extreme temperatures and occupants until the
alarm system is activated or the car is turned on.
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3.1.6 Reset Procedures
The following details the procedures for resetting both the system and the alarm.
The reset falls under two categories reset and preemptive reset. The reset restarts the
system and allows the driver or emergency personnel to resolve the situation. Preemptive
reset is used when no immediate environmental danger is present, but the alarm may still
go off. The reset procedures will meet the following functional requirements.
1.) If the reset is pressed while occupancy is detected and temperature is high, the
system must not reset.
2.) If the reset is pressed and temperature is not high but an occupant is detected and
the transmitter is out of range, the system resets the algorithm and the alarm.
3.) The alarm must turn off when reset.
4.) If the reset is pressed with no current alarm sounding, the system is preemptively
reset. The alarm will not sound as long as the temperature is not dangerously high.
5.) When the car is simulated to turn on, the system is turned off. The system resets
the algorithm and the alarm.
3.1.7 LabVIEW Setup
The following details the procedures for setting up the LabVIEW software on a
compatible computer. The LabVIEW application software is required in the prototype.
The LabVIEW Setup will meet the following functional requirements.
1.) LabVIEW must be installed on a computer with a compatible operating system
(Linux or Windows), with an available USB port.
2.) LabVIEW must be fully updated.
3.) Drivers for the DAQ must be installed.
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Lab 2 – Don’t Forget Me
4.) DAQ must be plugged into the USB port on the computer.
5.) Appropriate prototype sensors must be plugged into the DAQ.
6.) The Prototype VI file must be running.
3.1.8 Simulation Procedures
The simulation procedures are requirements for the simulation of data instead of
using the sensor’s input. Simulated sensors are necessary to fulfill the purpose of a real
sensor in the prototype without adding unnecessary complexity or cost to the system.
The simulation procedures will meet the following functional requirements.
1.) Data files must be proper format.
2.) Simulated values must be in appropriate range.
3.) LabVIEW must correctly wire into data files.
3.2 Performance Requirements
The following performance requirements describe how well the aforementioned
procedures work in quantifiable terms. All graphical requirements are to be completed
using the LabVIEW application. The following performance requirements directly relate
the procedures explained in the previous section.
3.2.1 DFM System Activation
The activation process tests each of the components in the DFM system to ensure
that errors are found before the system is relied on to save lives. As the system is
activated, the system will test if it is working properly. The system activation will meet
the following performance requirements.
1.) Each sensor will send a signal to LabVIEW.
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2.) Each sensor’s value will be greater than or equal to its rated minimum value.
3.) Each sensor’s value will be less than or equal t its rated maximum value.
4.) Each sensor will return a value within 10 seconds.
5.) The entire activation will take no more than 60 seconds.
3.2.2 Life Detection
The process of life detection uses the array of sensors to determine their combined
outputs that could indicate life. Each sensor contributes to the accuracy of the system.
Therefore, each sensor much be tested to ensure that it does not provide false data to the
Life Detection Algorithm. The life detection procedures will meet the following
performance requirements.
3.2.2.1 Sensor Performance
Each of the sensors used in the DFM system have very different types of data.
The data that it gives as output is specifically related to the medium the sensor is
evaluating. Sensor performance will be evaluated on the following criteria.
1.) The pressure sensor will be capable of determining pressure of at least one PSI.
2.) The motion sensor will be capable of determining vibration of more than 40dB.
3.) The pulse oximeter will be capable of determining finger pulse of 60-150bpm
(beats per minute).
4.) The microphone will be capable of determining sound of more than 10 dB.
(This space intentionally left blank.)
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3.2.2.2 Procedure Performance
Each of the sensors used in the DFM system have very different types of data.
The data that is sent by each sensor is directly correlated to its specific function. Sensor
performance will be evaluated on the following criteria.
1.) Each sensor’s value will be greater than or equal to its rated minimum value.
2.) Each sensor’s value will be less than or equal to its rated maximum value.
3.) Each sensor will return a value in less than one second.
4.) The entire procedure will take no more than nine seconds.
5.) Transmitter will send signal to receiver if occupancy is detected.
3.2.3 Environmental
This section describes the DFM system’s sole environmental sensor, the
temperature sensor. The sensor performance subsection describes the performance of the
temperature device alone. The temperature sensor is attached to the DAQ device
connected to the laptop through USB port. The next subsection, which is the procedure
performance, describes the performance of the temperature sensor in related to the life
detection algorithm of the DFM system.
3.2.3.1 Sensor Performance
This section describes the performance of the DFM system’s environmental
sensor. The temperature sensor is the sole environmental sensor of the DFM system. The
temperature sensor device will meet the following performance requirements.
1.) The temperature sensor is capable of reaching between the temperatures of 30 °F
and 90 °F, inclusive.
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2.) The DFM system will update the current temperature reading within less than 10
seconds.
3.) The temperature sensor’s value will be greater than or equal to its rated minimum
value.
4.) The temperature sensor’s value will be less than or equal to its rated maximum
value.
3.2.3.2 Procedure Performance
This section describes the procedure of the DFM system’s environmental
sensor. The temperature reading is essential, as it is part of the Life Detection Algorithm.
The procedure for temperature reading will meet the following performance
requirements.
1.) Must return a true value to the life detection algorithm if temperature reading is
30 °F or below or 90 °F or above.
2.) Must return a false value to the life detection algorithm if temperature reading is
above 30 °F and below 90 °F.
3.) Must keep sending the current reading to the life detection algorithm within less
than 10 seconds.
3.2.4 Transmitter and Receiver Functions
This section covers the performance of the DFM system’s transmitter and
receiver. The DFM system will use two Bluetooth communication devices for sending
and receiving signals. The light indicator on the DFM system’s GUI will light up
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steadily when the transmitter is within the range of the receiver. The transmitter and
receiver will meet the following performance requirements.
1.) The transmitter must be capable of sending a signal once every 10 seconds.
2.) The receiver must be capable of detecting the transmitter within 20 feet. Light
indicator will be off when transmitter is beyond 20 feet.
3.) The receiver updates reading every 20 seconds or less.
3.3 Assumptions and Constraints
Given the limitations of the prototype, the following assertions must be made to
ensure that the prototype has the functionality necessary to accurately emulate the fully
implemented version. Table 3 is a list of assumptions, constraints, and dependencies for
the prototype. Each element in the list was added to facilitate a successful demonstration
of the prototype.
Condition
Type
Effect On Requirements
30° F is the “cool” temperature at
which point alarm goes off.
Assumption
Cooling device must be present at
demonstration to lower temperature.
90° F is the “hot” temperature at
which point alarm goes off.
Assumption
Heating device must be present at
demonstration to raise temperature.
Detection of pressure indicates
detection of occupant.
Assumption
Prototype distinguishes between pressure
and no pressure; not between different
pressures.
Occupant has no remarkable
medical conditions.
Assumption
Medical conditions may affect input from
pulse oximeter.
Occupant is appropriately dressed
for the weather.
Assumption
Varied clothing affects effectiveness of the
system.
Reset switch is not used
accidentally or maliciously.
Assumption
Accidental or malicious use of the reset
switch defeats the purpose of the system.
CO2 sensor is not incorporated
into prototype.
Constraint
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Input from CO2 sensor is simulated by the
software.
Lab 2 – Don’t Forget Me
Condition
Type
Effect On Requirements
Heartbeat is detected by pulse
oximeter.
Constraint
Pulse oximeter must be attached to
occupant’s finger.
Prediction of extreme temperatures
is not supported.
Constraint
Alarm is only activated if an extreme
temperature is detected.
All sensors function properly at
time of demonstration.
Dependency
Prototype cannot be demonstrated without
input from the sensors.
PC or laptop with LabVIEW
installed is available at time of
demonstration.
Dependency
Prototype cannot be demonstrated without
the LabVIEW software.
Table 3. Effects of Assumptions, Dependencies, and Constraints on Requirements
3.3.1 Assumptions
Since the DFM system uses several sensors to evaluate the environment in the
vehicle, the sensors must be able to detect an environment that would be similar to the
environment of a potentially dangerous vehicle. The first two assumptions are that a
device will be present at the demonstration that will force the temperature sensor to read
values above 90° F and below 30° F. Since the room temperature cannot be changed so
dramatically in a short period of time, a device will be needed to facilitate the change in
temperature. Next, the pressure sensor, unlike the one implemented in the commercial
version, will not be responsible for detecting the variations in pressure from one moment
to the next. Instead, the pressure sensor will test whether or not there is force against it
and indicate that it detects a person accordingly.
The following two assumptions deal with the occupant and their possible health
and behavioral deviations from a typical passenger of the same age. Given that special
calibrations may be needed for occupants with health problems, it is assumed that the
occupant has no remarkable medical conditions. Any special calibrations for passengers
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Lab 2 – Don’t Forget Me
with health concerns will not be dealt with in the prototype. Secondly, since one’s
clothing could exacerbate the situation by prematurely over-heating or over-cooling him
them, it is assumed that the occupant is appropriately dressed for the weather. The
assumptions involving health and clothing are needed so the system does not need to be
changed in the event that the occupant is in danger before the extreme temperatures are
reached.
Lastly, while the reset switch is designed to prevent any accidental or intentional
harm, it is assumed that it will not be used maliciously. Given that the alarm cannot be
shut off while life is detected and the temperature is high or low, it is unlikely one could
manipulate the reset switch to cause harm to an occupant. Since the switch is to be used
with the understanding that the occupant is capable of leaving the vehicle at any time
before the temperature becomes extreme, the driver can use it to leave an occupant in the
car momentarily. Although the alarm will still go off when the environment becomes
dangerous, it may still result in the occupant being in the vehicle too long. This scenario
indicates that the driver understands their actions and manipulates the system to separate
their self from the vehicle before the alarm is set. The last assumption is that the driver
will not attempt to circumvent the safety features of the vehicle in order to deliberately
harm an occupant of the vehicle.
3.3.2 Constraints
In order to develop the DFM system prototype in a timely manner, some of the
features to be implemented in the final version had to be reduced. First, the CO2 sensor,
unlike the other sensors used in the prototype, will not be physically implemented.
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Lab 2 – Don’t Forget Me
Instead, reading from the sensor will be from a table of previously generated values. By
generating the values rather than implementing the actual sensor, the prototype can be
constructed with less effort and cost. Likewise, all of the other sensors will have their
output data stored in a table to ensure that the DFM system prototype will be functional
despite any hardware malfunctions.
Secondly, the pulse oximeter differs greatly from the accelerometer in that it
measures the pulse analytically rather than directly. An accelerometer can be
implemented so that it can detect the vibrations of ones heartbeat and analyze the
vibrations to determine a pattern. The pulse oximeter does not actually measure one’s
pulse; instead, it measures the intensity of the infrared light after it passes through a
human’s finger. The reason infrared light is measured is because the intensity varies with
the amount of oxygen in the medium it is traveling through. In other words, infrared light
travels through oxygen rich blood better than oxygen deficient blood. As the heart beats,
it supplies the body with oxygen rich blood and changes the way infrared light passes
through one’s finger. The variations in the oxygen levels of a person’s blood are directly
correlated with their heart beats. The infrared light can be used to measure a heart beat.
By using the pulse oximeter instead of an accelerometer, the prototype is constrained by
the fact that the occupant must attach the pulse oximeter to their finger, which would be
very inconvenient in the final product.
Lastly, the final product will be able to determine when the car’s temperature will
become dangerous by analyzing the change in temperature over time. The prototype is
not capable of determining the temperature change; rather, it assesses the temperature’s
current value alone. While the final product will be able to preemptively set off the alarm
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Lab 2 – Don’t Forget Me
if it detects that the car will become dangerous in a matter of minutes, the prototype will
set off the alarm only when danger is eminent.
3.3.3 Dependencies
The two dependencies for the prototype are both based on the method in which it
is being implemented. First, the hardware will function properly at the time of
demonstration. It may be possible to conduct the demonstration using only virtual
sensors; however, the prototype would lose all credibility if its most innovative aspect,
the array of sensors, did not even function. In order to have a successful demonstration,
it is imperative that all sensors it is designed to run with are fully functional.
Secondly, the software that is being used to write the logic for the DFM system
and integrate the sensors will not only be installed but working for the demonstration.
Given that every aspect of the prototype interacts through the LabVIEW software and the
data acquisition device, it is of the highest level of importance that its software can run
throughout the demonstration.
3.4 Non-Functional Requirements
The non-functional requirements are the aspects of the prototype that are outside
the core innovative functionality of the system. They are security, maintainability, and
reliability. Each of these aspects are important to the success of the product.
3.4.1 Security
The security of the DFM system and the vehicle are issues of little concern. In
the event that the integrity of the product is compromised, no harm can come to the user
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Lab 2 – Don’t Forget Me
financially or physically. The DFM system does not store any information about the
passengers of the vehicle or any long-term records.
The DFM system has no control over the vehicle other than the horn and therefore
cannot be manipulated to achieve entry into the vehicle. Any attempt to break into the
vehicle while the DFM system is activated would likely result in the alarm being
activated unless the individual also had the key fob device on their person. Under no
circumstances does the DFM system compromise the security of the owner’s car or
personal information.
3.4.2 Maintainability
In the event that the activation sequence indicates that one or more aspects of the
DFM system are not fully functional, a warning light will be lit on the driver’s warning
panel. The DFM system will continue to run without the specific component until it can
be examined by a professional. If it is determined that the DFM system is impaired to the
point where it cannot function in a successful manner, the system will be completely
disabled to prevent false alarms. Since the automobile manufacturer has liberty over the
specific implementation of the system, it is their responsibility to integrate the system
into their set of diagnostic tools. The DFM system will provide the necessary outputs to
be integrated into the diagnostic kit the manufacturer designs.
3.4.3 Reliability
The DFM system must run continuously when the vehicle is not on to ensure that
no life is present inside at any time. Likewise, the DFM system must go through the
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Lab 2 – Don’t Forget Me
activation sequence every hour to ensure that all sensors are performing accurately.
Since the system is autonomous, there will be few instances when the driver must
actually interact with the system. It is the responsibility of the system to work without
the driver’s effort and to consistently check that the data it is analyzing is accurate.
4
APPENDIX
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 DFM System:
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
Linear Thermistor Air Temperature
Pulse Oximeter
Part #
136654
218827
177092
OL-706
http://www.fitness-equipment.com/acatalog/
Online_Catalog_Pulse_Monitor__Ear_Clip_
for_Pulse_Monitor_1034.html
P-703A
779320USB-6008 Kit (LabVIEW and DAQ)
22
Company
Qty Price Ea Total
Jameco.com
2
$7.95
$15.90
Jameco.com
2
$8.99
$19.98
Jameco.com
2 $24.95
$49.90
Omega.com
1 $61.00
$68.00
FitnessEquipment
2
$19.99
$39.98
NI.com
2
$159.00
$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
1
Price Ea
Total
$37.00
The following University resources are required to support the prototype development
and demonstration:
1
Laptop/ Second computer
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$37.00
Lab 2 – Don’t Forget Me
1.1 It will be used to display the interaction of hardware element and
the algorithm processes during the live prototype demonstration.
1.2 Windows XP with connection to the internet
1.3 Quantity: 1
1.4 Date required: March 1, 2008
1.5 Deliver to: Don’t Forget Me Inc.
2
LabVIEW installed on the Laptop
2.1 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.
2.2 LabVIEW must have the drivers installed for the DAQ used in the
prototype, a USB-6008.
2.3 Quantity 1
2.4 Date required: March 1, 2008
2.5 Deliver to: Don’t Forget Me Inc.
38