Download ppt

ECE 477 Design Review
Group 7  Spring 2005
Outline
•
•
•
•
•
•
•
•
•
•
Project overview
Project-specific success criteria
Block diagram
Component selection rationale
Packaging design
Schematic and theory of operation
Preliminary PCB layout
Software design/development status
Project completion timeline
Questions / discussion
Project Overview
An autonomous vehicle designed to look for
moving heat-emitting targets and engage them
while patrolling a limited area and avoiding
ground obstacles.
+
=
Project-Specific Success Criteria
• An ability to detect a heat-emitting target
• An ability to determine and display the number
of engagements and battery level
• An ability to fire the weapon
• An ability to turn weapon to face target
• An ability to avoid collisions with inanimate
objects
Block Diagram
AirSoft gun
(1)
Passive IR
sensors
(4)
LCD screen/Shift
Register
(1)
Ultrasonic sensor
(1)
Freescale
HC(S)12
(1)
H-Bridge for Drive
Motors
(1)
Servo motor
(1)
Component Selection Rationale
•
•
•
•
•
•
•
Microcontroller
Ultrasonic Sensors
Passive Infrared Sensors (PIR)
Robot Base
Liquid Crystal Display (LCD)
Servo Motor
Paintball Gun
Component Selection Rationale
• Micro-controller: Motorola M68MOD912C32
- Pre-made DIP Module
- Contains requisite I/O
- Instruction Set/Capability Familiarity
Component Selection Rationale
• Ultrasonic Sensors: Devantech SRF04
- Ease of use
- Small size
- Low cost
Component Selection Rationale
• Passive Infrared Sensors: Kitsrus K30
- Easy to interface.
- Good range ( Approx. 120 degree spread )
- Low cost
Component Selection Rationale
• Robot Base: Rogue Robotics RT-ATR
- Easy to control ( 2 geared motors )
- Flexible/Expandable design
- Multiple levels
- Came with H-bridge
Component Selection Rationale
• Liquid Crystal Display: Optrex DMC20261A
- Free
- 20 Chars x 2 Lines
- Backlit
- Heavy-duty
Component Selection Rationale
• Servo Motor: JR NES-537
- Easy to interface/operate compared to stepper motor
- High torque rating ( 45 oz-in )
- Very small/lightweight
- Low cost
- 120 degree range
Component Selection Rationale
• Paintball Gun: KTC 210910
- Fully Automatic
- Electronic Trigger
- Small ( 9” after cut down )
- Light weight ( less than 1 lb )
- Easily interfaced
Packaging Design – Front View
Packaging Design – Side View
Schematic/Theory of Operation
•
•
•
•
•
•
•
•
Voltage regulators
LCD interface
PIR interface
Ultrasonic sensor interface
Servo interface
H-Bridge and drive motors interface
Gun trigger interface
Battery level indicator
Schematic/Theory of Operation –
Voltage Regulators
• Power supply for microcontroller module and
other digital components:
– Linear Tech LT1376-5 switching regulator
– Step down from 14.4 V input to 5 V
regulated output
– Can supply up to 1.25 A current
– Up to 88% efficiency, typically around 86%
Schematic/Theory of Operation –
Voltage Regulators
• 10 mH Inductor because the current draw could be
more than 0.6 A
Schematic/Theory of Operation –
Voltage Regulators
• Power supply for motors:
– Linear Tech LT1374-5 switching regulator
– Step down from 14.4 V input to 5 V
regulated output
– Can supply up to 4.25 A current
– Up to 90% efficiency, typically around 88%
Schematic/Theory of Operation –
Voltage Regulators
• 10 mH Inductor because the current draw could be
more than 3.5 A
Schematic/Theory of Operation –
LCD interface
• Utilizes the SPI capability of the MCU
• A shift register, 74HC164, will be used to register
data to be displayed on the LCD
• Pin PM5 will be used to supply SCK to the shift
register
• Pin PM4 will be used to supply SDO to the shift
register
• Pin PM3 will be used to supply RS to the LCD
module
• Pin PM2 will be used to supply Enable to the LCD
module
• A 7x2 header will be used to connect LCD to the PCB
Schematic/Theory of Operation –
LCD interface
Schematic/Theory of Operation PIR interface
• Four PIR (passive IR) sensors to detect heat
emitting moving objects
• AN0 to AN3 will be used to receive the inputs
from the sensors
• 9 V pulse when a heat emitting moving target
is detected
• A voltage divider is used to reduce the
voltage input to the MCU to 5 V
• Resistors with the values of 1 kW and 1.2 kW
will be used as the voltage divider
Schematic/Theory of Operation PIR interface
Vout = (Rbelow/(Rup+Rbelow)) * Vin
5 = (Rbelow /(Rup+Rbelow)) * 9
Rbelow
/(Rup+Rbelow) = 5/9
1.2 kW / (1kW + 1.2 kW)  5/9
Schematic/Theory of Operation Ultrasonic interface
• PT7 will output trigger pulse to
the sensor
• PT6 will receive the input pulse
from the ultrasonic sensor
• Distance is determined by how
long the input pulse is held
high
Schematic/Theory of Operation Servo interface
• Pin PT4 will be used to
output pulses regulated
by the built-in PWM to
the servo to rotate the
gun turret
• Wiring setup image
courtesy of Parallax,
Inc.
Schematic/Theory of Operation H-bridge and motors interface
• PT0 to PT3, will be used as
output pins to the H-bridge to
drive the direction of the robot
and PWM will be used to control
the speed of the motors
• Drive motors will be connected
and powered through the Hbridge
• The power supply to the drive
motors will be regulated by the
LT 1374-5 converter
• The H-bridge’s power will be
regulated by the LT 1376-5
converter
• H-bridge image courtesy of
Rogue Robotics
Schematic/Theory of Operation Gun trigger interface
• PM0 will be used as
trigger
• The gun will be optically
isolated from the MCU
• 4N28 opto-isolator will be
used
Schematic/Theory of Operation Battery level indicator
• AN4 will be used to receive an analog voltage
reading from the power supply to indicate the
current level of the battery
• 10-bit analog input and the analog to digital (A/D)
converter will convert the input voltage to a digital
value that can be used to compute the current
battery level
• Will be displayed on the LCD
• A voltage divider is used to reduce the voltage input
to the MCU to maximum 5 V
• Resistors with the values of 2.2 kW and 1.2 kW will be
used as the voltage divider
Schematic/Theory of Operation PIR interface
Vout = (Rbelow/(Rup+Rbelow)) * Vin
5 = (Rbelow /(Rup+Rbelow)) * 14.4
Rbelow
/(Rup+Rbelow) = 5/14.4
1.2 kW / (2.2 kW + 1.2 kW) 
5/14.4
Preliminary PCB Layout
Start
Reset Gun
Clear LCD
Display
Battery Level
Software Design
Pause for
10 Seconds
Display
Engagements
Set
Engagement
Flag
Fire
Weapon
Stop Turret
Yes
Poll PIR Sensors
Which PIR
Sensor?
Target
Detected?
Yes Turn Motors
OFF
No
1
2
3
Turn Turret
Left
Turn Turret
Right
Spin Grover
180o
Poll Ultrasonic
Sensor
Turret Sensor
Triggered?
No
Turn
Maxed?
No
Yes
No
Stop/Reset Turret
Yes
Turn 90o
Right
Turn Motors
OFF
Obstruction
Detected?
Spin Grover 90o
in Same Direction
Turn Motors
ON FWD
Yes
No
Engagement
Flag Set?
Increment
Engagement
Count on LCD
Clear
Engagement
Flag
Project Completion Timeline
Week
8
9
Project Completion
- Finish PCB layout and fit parts to printout
- Receive final O.K. from Chuck
SPRING BREAK (Gambling in VEGAS!)
10
- Start mounting parts to PCB
- Continue with software prototyping
11
- Start interfacing software with hardware
12
- Finish up on packaging with gun turret and servo motor mount
13
- Finish software interfacing
- Begin working on user manual
14
- Finish user manual
- Work on demonstration video and final presentation
15
- Final Presentation
Questions?