R.F.N.T.
(Radio Frequency Navigational Tracker)
Capstone Fall 2004
Josh Bingaman
Ryan Hitchler
John Maitin
Fabien Nervais
Matt Sharp
Main Objectives
 Create a vehicle that will remotely track a
high frequency RF transmitter, which may or
may not be stationary.
 Detect the signal strength of the target in
order to determine which direction to go.
 The practical application is a golf caddy that
will follow a golfer when requested.
Possible Project Extensions
 Add proximity sensors in order to
circumnavigate obstacles.
 Cell phone used to control vehicle.
 GPS navigation.
 Signal Acquisition Improvement
 Additional RF controlled functions.
Basic Layout
Antenna
Unit
Base of
vehicle
Processor
(Inside
Base)
Hardware Block Diagram
Processor/ Main
Board
RS/232
RSSI
Digital
Compass
GPIO
Antenna Unit
Motor
Motor
Control
GPIO?
Motor
(Left)
Motor
(Right)
Digital
Compass
RS/232
Base of Vehicle
Software Implementation
 One basic algorithm, two variations

Initial design
Antenna stops spinning
 Unit stops to turn


Desired design
Antenna continuously spins
 Unit turns dynamically

Algorithm For Operation (Initial)
Algorithm For Operation (Desired)
Mechanical & Control Systems
Potential Concerns / Unknowns
 Rotating Antenna &
Motor Mount
 Antenna Construction
& Actuator Torque
 Ground Wheel Control
 Sensor Resolution
 Terrain
 Tower Height Control
Addressing Anticipated
Difficulties
 Rotating Antenna & Mounting Motor
 Wheel vs. chain
 How to attach, depends on dimensions
 Antenna Weight / Shape & Actuator Torque
 dependant upon antenna implementation
 wind resistance, etc…
 Ground Wheel Control
 motor specs unknown, researching new motors
 possible substitutes – how to mount??
Difficulties Part Deux
 Sensor Resolution
 Compass
 magnetic distortion maybe present
 hard-iron calibration should be performed
 Data acquisition issues
 Frames of reference
 Terrain too rough
 considering additional functionality, safe mode / shutdown
 vehicle durability
 Tower Height Control
 motor specs unknown, may not be necessary
 Automate signal query
Power Specifications
 12V car Battery, AA/AAA Battery, Dry Cell
 Two 12V wheel motors
 One 5V antenna motor
 Base and antenna Circuitry
 Low-powered transmitter
Transmitter
 Low power transmitter

ideally a remote (key-fob)
Overview of Power Concerns
 Power transformation on navigational unit
 Power noise due to rotation
 Power cable routing to rotating mount
Power Concerns Addressed
 Power transformation on navigational unit

Voltage regulators
 Noise due to antenna rotation

Decoupling caps
 Power cable routing to rotating mount

Rotating contact plates
Rotating Mount
• Transmitters
• Grooved Plates
• Software
Antenna
 Rotating Mount
 Shielded
Unidirectional Antenna
 Digital Compass
mounted with Antenna
 Synchronization of
Compass and Antenna
Transmitter/Receiver
•916 MHz RF
•16 Bits Transferable
•RSSI (Relative Signal Strength Indicator)
Schedule
Thank You
Questions
?