Transcript Yagi VS Omni directional antennas

Easy on the Tini
Cell phone detector
Bill Barker
Carey Davis
Ben Irwin
Travis Majors
Description and Goals
To create a robot that detects RF signals
(cell phone signals) then moves toward the
strongest signal.
Notifies cell phone user about use in that
area.
Outline of Approach
Create a robot with two servo motors
Fashion RF detecting antenna(s) on the
robot chassis
Mount IR sensors to aid robot movement
Use display, lighting, sounds, etc. to deter
cell phone use
Design a microcontroller to interface the
systems
Hardware Implementation
Home Base
RF Beacon
RF Signal
Detection
IR Object
Detection
Microcontroller
Motor
Controller
Motor
Feedback
Servo
Motors
Data/ Programming
interface
Signal
Disruption
Implementation of Subsystems
The Robot
Metal platform from
previous project
Two 9FGHD Ferrite
Series ServoDisc
Motors
Robot Movement
Autonomous
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Object Detection
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Infra-Red
Home Base Detection
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RF
Programmable Search Pattern
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Signal Detection Sweep
Identify and approach appropriate signal
Scenario #1
Signal Found
Scenario#2
No Signal Found
Signal Found
Object Detected
No Signal Found
IR Object Detection
Sharp GP2D12
Analog output voltage
Vcc-.3V to .6V based on
distance from object
0cm to 80cm
The Motor
9FGHD Ferrite Series
ServoDisc Motor
Input voltage -12V to
+12V
Capable of 1.5 N-m
continuous torque
Motor Drivers
Microcontroller delivers signal voltage to
drivers using PWM
Driver performs DC/DC conversion to step
up input signal voltage to -12V to +12V
output motor voltage
Motor Encoders
Encoders such as the
HEDS-5500 mounted
on each motor
Signal Detection
Robot Signal Detection
Overview: This part of the robot will detect signals
within the GSM frequency-band that will then be
translated into data that will control the robots
movement in pursuit of a detected strong signal. This
will be done by the following devices:
Tuned directional antennas
 RF signal intensity meter
 Voltage processing component
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Tuned Directional Antennas
This component will give directional ordination to the
robot to pursue the signal.
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A Yagi antenna will be used to hone in on the signal.
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Antennas Specifications:
GSM: Uplink 890-915MHz and Downlink 935-960Mhz
PCS band: 1.7-1.99 GHz
Directional Capability
Yagi VS Omni directional antennas
RF Signal Intensity Meter
This simplified circuit will take the antenna’s RF
signal as an input and will output a voltage that is
proportional to the signal’s intensity.
Voltage Processing Component
Feed measured voltage into the micro-controller’s
A/D converter.
Have the microcontroller only sample at what is
realistic to match the motor’s encoder data.
Store both RF intensity and robot direction data
for a full revolution in on-board RAM.
Find peak voltage within data and have robot
return to this recorded direction.
Microcontroller
Prototype Board for MSP430-F1611
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Multiple A/D converters
Expanded RAM to 10K bytes for greater storage capacity
PWM capabilities for motor control
Good tools and easy debugging
Cost effective solution of our application
Power Distribution
Power Distribution and
Peripherals
Voltage Variations

Driver motors, Lights,
Speakers, Sensors,
Circuitry, Display
screen
Voltage regulators or
converters
Recharging at “home”
Power Distribution and
Peripherals-Battery
2 BP7-12 12 V 7Ah
Batteries to power the
robot
5.94” x 2.56” x 3.98”
6 lbs.
Disruption Handling
Disruption Handling
Robot Modes

Hospital Mode
Robot looks for over any amount of time, suggesting
a data transmission
 Turn off your cell phone!
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Silent Mode
Robot looks for signal lasting for awhile, suggesting
a call vs. a text message
 Quiet your phone!
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Disruption Handling
Disruption of Call
LCD screen for message
 Lights, sounds
 Physically disrupt the call?

Home Base
Home Base
Robot will be able to autonomously return
to a given “home base” for a variety of
reasons:
Battery charge level
 Set time period
 Called back by us
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Home Base
Recharge Station
RF “Beacon”
Data Sync
Home Base –RF “Beacon”
To call the robot home a signal within the
robots detection bandwidth will be emitted.
Constant frequency within range of detection
device
 Higher power to override cell phone signals.
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Same intelligence used to follow cell phone
signals will be used find the home base.
Home Base-Programming
Home Base will be used to reprogram
different parameters of the robot such as:
Search Pattern
 Search Time
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Risks/Contingencies
Risk/Contingency #1
Risk: It might be impossible to legally
physically disrupt the cell phone signal.
Contingency: Robot will ask user to turn off
phone via basic display/sounds.
Risk/Contingency #2
Risk: Difficulty to differentiate between cell
phone signals and other RF signals.
Contingency: Setup closed environment
with little outside interference and use a
strong set signal to test tracking ability.
Risk/Contingency #3
Risk: Complexity of artificial intelligence
and automation.

Object avoidance while tracking signal.
Contingency: Test in empty room to
simplify coding.
Risk/Contingency #4
Risk: In areas that RF transmissions are not
allowed, our home beacon will not suffice.
Contingency: Program return path or
remember path traveled in order to return
home.
Scheduling, Costs, and Labor
Prelim Schedule
Milestones
Milestone 1:Robot moves towards test
signal
Milestone 2:Programmable search
parameters, IR object detection integration,
home base construction complete
Expo:Robot and home base fully functional
Cost Estimations
Thank you!
??Questions??