ECE 477 Design Review
Team 6  Spring 2011
Left to right: Kirk Iler, Brian Bentz, Stephen Wolf, Fuhe Xu
Outline
•
•
•
•
•
•
•
•
•
•
Project overview
Project-specific success criteria
Block diagram
Component selection rationale
Packaging design
Schematic and theory of operation
PCB layout
Software design/development status
Project completion timeline
Questions / discussion
Project Overview
Defender is a basic defense system designed to
identify and neutralize hostile targets. It combines
a number of modules to create a turret-mounted
defense system.
Modules:
•Coilgun
•Motor system
•Image processing
•Ethernet connectivity
Project-Specific Success Criteria
• 1. An ability to fire a projectile using magnetic
force
• 2. An ability to aim the projectile by controlling of
the azimuth and elevation angles of the barrel
• 3. An ability to charge a capacitor bank to a
variable voltage, up to 400V
• 4. An ability to gather images and perform target
recognition and tracking
• 5. An ability for a user to enter commands and
display the status of the turret through an external
interface
Block Diagram
Component Selection Rationale
• Camera
– Canon VC-C50i with PTZ
• Atom Board
• Capacitors
– 3900μF
– 400V max electrolytics(x4). U32L
Microcontroller
•
PIC24FJ64GB002
– 16bit
– 64KB flash/8k RAM
– 16MIPS
– 3.3V
– 44 TQFP
– 5 Timers
– 1 USB OTG
– 2 I 2C
– 15 remappable pins
Firing Controls - IGBT
• Criteria:
– Voltage
– Amperage
– Heat dissipation, Failure mode
– Price
• Part chosen:
– APT200GN60JDQ4
• 600V, 283/600A
• 640W, .25°C/W
• $42.60
• No sink
Motor
42BYG023-R
•
•
•
•
•
Step angle:
Rated voltage:
Current per phase:
Holding torque:
Mass:
1.8°±5%
12V
0.4A
2kg/cm
0.2kg
Stepper Motor Controllers
• DRV8821 from Texas Instruments
• Controls 2 stepper motors up to 1.5A each
•
8-40V stepper motors
• Microstepping modes
• Edge triggered digital stepping via PWM from
Micro
Packaging Constraints
• Portability – Defender should be easily moved and
installed.
• Weight – lightweight to allow for small motors
• EMI resistant – To protect circuitry from strong fields
present in coil gun.
• Firing range – Target over a broad area.
• Keypad – Interface must be easily accessible.
Packaging Layout
• Four major physical components:
– Base: Divided metal box containing control circuitry,
high voltage capacitors, and power supply.
– Rotator: Uses stepper motors to aim the Coil Gun;
Mounted on top of Base.
– Coil Gun: Mounted on top of Rotator.
– Camera: Mounted on top of Base.
Schematic/Theory of Operation
Subsections:
High voltage
Control microcontroller
Capacitor bank
Atom processor
Motors
Power Supplies
• 3.3 V low drop out linear
regulator
• Provides power to the control
microcontroller
• Supplied by rectifier from high
voltage system
• Switching 12 V power
supply (4 Amps)
• Supplies power to the Atom
and the motors
• Supplied by second
transformer on Power PCB
Motor Microcontroller
•
•
•
•
•
•
Controls 2 direct drive stepper motors with two coils each
10 heat sink grounds to copper heat sink
Dedicated I2C port expander
Commands include reset, direction, decay mode, step mode
1/8th microsteps
Sense resistors and voltage reference limit current to 400 mA
Control Microcontroller
• Receives commands from Atom
• Communicates information to
and from circuitry
• I2C communication bus (400 kHz)
• USB connection to atom
• Bypass capacitors
• Reset circuit
Other Components
Keypad Encoder
• Sends an interrupt
directly to the
microcontroller to signal
available information
• Microcontroller collects
information over I2C
• The photogates will
function by creating a
logic high when an
object passes through.
• These will be directly
interfaced to general
purpose I/O pins.
Atom processor
• Performs image processing and system command
• Communicates with control microcontroller over USB
• Communicates with user interface over Ethernet.
Power PCB Schematic
High Voltage Power
• Changed to
TRIAC circuit
to switch
power.
• Measure DC
voltage using
ADC.
Rectifiers and I2C
• 12V transformer and bridge
rectifier connects to
Communication Control PCB.
• 3.3V bridge rectifier.
ADC, LED switch, Coil
Protection Diodes
• Capacitor bleed
circuit connects to
capacitor bank.
• ADC measures
current through a
voltage divider.
• Protection diodes
anti-parallel to coil.
Power PCB Layout
Communication PCB Layout
Software Design/Development Status
• Computer
– Single Executable:
• GUI - implemented
• Java.swing components
• Ethernet - testing
• Wrapped in to GUI components
• Jnetpcap library
Software Design/GUI Prototype
Software Design/Development Status
• Microcontroller
• USB interface- not yet begun
• Communicates with atom board
• I2C bus to interface to:
• Motor microcontroller
• Charging controls
Software Design/Development Status
• Atom Board
– Single Executable:
• Ethernet libraries- testing
• Winpcap library
• USB libraries- not yet begun
• PIC family libraries
Camera status
• Microsoft Visual Studio 2008 configured
• OpenCV image recognition libraries and
camera motor libraries installed
• Drivers installed for S-Video frame grabber
and motor USB to serial cables
• Image capture functioning on computer
intended for compiling
• Minor configurations still needed on Atom,
which will be running the executables
Project Completion Timeline
• 3/11
• 3/21
• 3/28
•
•
•
•
4/10
4/11
4/18
4/27
PCB submission
Atom board Ethernet communication
Image processing recognizing stationary targets
Start populating PCBs and testing
Start programming microcontroller
Begin physical packaging
Completed packaging and testing
Start system integration
Documentation and paperwork
PSSC Demos
Questions / Discussion