Transcript presentation

ECE 445 Group 20
4/23/2012
Kevin Dluzen
Jonathan Hall
Diyang Qiu
Motivation
Current golf ball retrieval systems are…
Manually driven
Costly
Gas powered
Our robot is…
Autonomous
Cheap
Solar powered
Features
 Locates golf balls in front of robot and directs 2
front mounted motors to nearest ball
 Picks up golf balls while moving and stores them
in container
 On board power management system allows for
PV charging while operating
 Detection system for number of balls collected
and manual emergency disable switch
Major Modules
1. Mechanics
 Pick up wheel
 Robot structure
2. Control
 Vision processing
 Sensors
3. Motors
 Motor/ H-bridge design
4. Power
 Solar power
 Power management
Electrical System Overview
1. Mechanics module
Evolution of mechanical design
1. Mechanics module
Final Mechanical Design
18” x 16” footprint, 20” tall
2 front motors, 2 free castor wheels
Sprocket driven pick up wheel
1. Mechanics module
Pick up mechanism
1. Golf ball pushed through thin film into 14”D wheel
2. Rides up the wheel via 6 pairs of L-shaped brackets
3. Pushed out through thin film
4. Rolls down incline and into container while triggering push button
Pickup wheel in action
2. Control module
Vision processing components
Camera (Fire-i digital camera)
 640 x 480 RGB resolution
 30 fps
Compact Vision system (NI CVS-1456)
 2 TTL inputs/ 10 TTL outputs
 3 IEEE 1394 input ports
 Configurable FPGA for I/O control
 Runs via LabVIEW code
2. Control module
Vision Processing Steps
1. Threshold image based on gray scale value of
each pixel
2. Complete circles, filter out big/small blobs,
identify circles
2. Control module
Ball positions to outputs
LabVIEW code:
1) Identify nearest ball based on y coordinates of balls
2) Identify state based on x position of nearest ball
3) Halt state triggered with disable switch or ball counter
State:
1- Halt
2- Straight
3- Turn right
4- Turn Left
Left PWM
0%
70%
40%
70%
Right PWM
0%
70%
70%
40%
2. Control module
Vision system in action
2. Control module
Golf ball counter
 Push button mounted above container
 CVS counts number of low to high changes
 Disables motors when maximum ball count reached
 Count resets via disable switch
3. Motor Module
H-Bridges and Motors
o 2 front mounted 12V DC parallel
shaft gear motors
o Direct shaft drive system
o Pick up mechanism driven by chain
drive
o Axial driven pick up mechanism
3. Motor Module
H-Bridges and Motors
H Bridge Design:
oDC Motor Control Using
PWM
oConcerns about flyback
voltage
oConcerns about heating
(operational frequency)
oHigh side N-type Mosfet
bootstrapping
oHIP4081 Mosfet Driver
CONTROL SIGNALS
AHI
FORWARD
BACKWARD
DISABLE
BHI
ALI
BLI
DISABLE
PWM
0
0
1
0
0
PWM
1
0
0
X
X
X
X
1
3. Motor Module
Progression of H-Bridge
Construction
o H-bridge Construction from prototype to PCB
o PCB creation and Eagle CAD software
o Included surface mount components for final
design
3. Motor Module
TOP
PCB DESIGN
BOTH
BOTTOM
3. Motor Module
H-Bridge Testing
o Heating to less than 40deg C above
ambient
o Must operate with 3-12 V logic PWM
o Must output proper functions for
motor control as defined by Control
table
4. Power module
Power management components
Solar Panel

12 Volt 5 Watt Trickle Charger

Charge Controller
Lead-Acid rechargeable Battery

12 Volt

5Ah
4. Power module
Power management components
Battery Management Circuit
o SPDT dual relay
o BJT (NPN, β=100)
o Arduino UNO
o Voltage regulator (Vin=12V, Vout =5V)
o Current Sensor (Low current sensor)
4. Power module
Testing circuit
BJT circuit
Regulator circuit
4. Power module
Arduino Features
Power source

The battery powering the system

5 Volts from the voltage regulator
Senses system voltage

Implement switching operation when voltage lower than 10.5
Sense the solar panel power condition

Current sensor converts current signal to voltage signal

Voltage sensed by Arduino
4. Power module
Power Management Circuit
4. Power module
Switching results for different battery situation
Relay operation steps
B2 LOW
B1 HIGH
Relay 4
on
Relay 3
on
Relay 1
on
Relay 2
on
Relay 4
off
B2 HIGH
B1 LOW
Relay 4
on
Relay 2
off
Relay 1
off
Relay 3
off
Relay 4
off
B1 LOW
B1 LOW
Shut down the system and wait for battery to be
charged by the solar panel
Summary
Summary
The Green Retriever is…
Autonomous
Cheap
Solar powered
Additional Features
 Can be charged while operating
 Counts number of balls collected
 Can turn on a dime
Recommendations
 More sophisticated search algorithms
 Use data from PV panel for maximum power point
tracking
 More powerful motors for higher collection speeds
 Multiple pick up wheels
Acknowledgments
 Alex Suchko (Amazing TA)
 Greg Bennett (Machine Shop)
 Skot Wiedmann (Parts Shop)