Transcript Autonomously Controlled Front Loader

Autonomously Controlled
Front Loader
By: Steve Koopman
and Jerred Peterson
Advisor: Dr. Schertz
Presentation Outline
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Project Introduction
Hardware Design
Software Design
Final Progress
Future Work
Conclusion
Questions
Presentation Outline
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Project Introduction
Hardware Design
Software Design
Final Progress
Future Work
Conclusion
Questions
Project Introduction
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Project Motivation
Work towards a fully automated system, such as
a gravel yard
 Investigate small-scale operation of
autonomous vehicle
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Can model several interacting robots cheaply,
without risk of damage
 Allows work to be done towards full-scale operation
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Starting point for additional small autonomous
vehicles
Project Introduction
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Specific Project Goals
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Modify toy vehicle to do simple tasks
Load a bucket with material
 Dump material into truck
 Repeat until the truck is full
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Vehicle operates autonomously
 Low cost vehicle design
 Flexible design for future expansion
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Project Introduction
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Project Goals for Tasks
Rotate vehicle until loading bin located
 Line up with bin, drive to it
 Lower bucket and load material
 Raise bucket and leave bin
 Rotate until truck located, line up with the truck
 Drive to truck, dump material into it
 Repeat process until truck full
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Project Introduction
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System Block
Diagram
Repositions
Bucket and Arm
Moves and
Rotates Vehicle
Real World Environment
Ultrasonic
Sensor
Infrared Detector
Compass
Object Distance
Target Detection
Heading Information
Microprocessor
Arm and
Bucket Position
Arm/Bucket
Control Circuitry
Track Control
Circuitry
Arm/Bucket
Motors
Track Motors
Arm/Bucket
Position Sensors
Infrared
Encoders
Distance
Traveled
Measurements
Presentation Outline
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Project Introduction
Hardware Design
Software Design
Final Progress
Future Work
Conclusion
Questions
Hardware Design
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Design Steps
Vehicle Choice
 Sensor Choice
 Circuitry Design
 Circuit Board Construction
 Microcontroller Interfacing
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Hardware Design
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Vehicle Choice
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Hobby Kit Vehicle (Tamiya hobby
kit)
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Bobcat RC Vehicle (Bobcat T190)
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2 drive motors, arm raise motor
Easier to expand
Weak lifting capacity
2 drive motors, arm raise motor,
bucket dump motor
Internal limit switches
Harder to modify
Continued with Bobcat Vehicle
Hardware Design
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Sensor Choice
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SRF05 Ultrasonic Sensor for
Distance Measurement
Can operate down to ~1 inch
 Used in previous projects
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PNZ109L-ND Infrared (IR)
Transistor for Object Detector
Detects IR LED at ~5 feet away
 Little issue with stray IR interference
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Hardware Design
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Sensor Choice
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Vector V2x Compass for Heading Information
~1 degree resolution
 Serial output
 10 Hz update rate
 Continuous sample mode
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Hardware Design
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Sensor Choice
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HOA0149-1 IR reflector/emitter
for Rotary Encoder
Small size
 Good signal result
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Rotary Encoder Wheel Pattern
8 pulses per revolution
 Mounted directly to drive wheel
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Hardware Design
Hardware Design
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Circuit Design
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Motor Circuitry
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Quadruple Half H-bridge
L293 chips
 High Current output
for motors
 About 3W power
dissipation on chip
Logic circuitry
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Easier microcontroller
interface
Protects bucket and
arm motor
Hardware Design
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Circuit Design
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Infrared Sensors
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Infrared transistor
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Op-amps increase
transistor distance
Schmitt-trigger to
reduce noise
Infrared Encoder
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Bias circuitry for
normal operation
Schmitt-trigger to
reduce noise
Hardware Design
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Circuit Board Construction
Perforation board used for flexibility
 2 circuit boards
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Compass board to hold digital compass
 Main circuit board for rest of circuitry
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Surface mount sockets hold Integrated Circuits
(IC’s)
 Wire-wrap and Soldering used for circuit
construction
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Hardware Design
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Circuit Board Construction
Terminal Strip used for power connection
 Single and Double Pin Headers for external
connections
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Single pin headers connect to motors and sensors
 Double pin header connects to microcontroller and
compass board to main circuit board
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Hardware Design
Circuit Board Construction
Circuit Board
Layouts
Main Circuit Board
IR Rec
Opamp
IR Encod
IR Encod
SchmittTrigger
And Chip
H-Bridge
mtr
mtr
2.5"
Not Chip
m sens
3V to 5V Buffer
Component
m sens
2.5"
3V to 5V Buffer
Component
mtr
And Chip
3V to 5V Buffer
Main Board
Connection
H-Bridge
mtr
Opamp
Compass Circuit Board
Compass
(Must be on separate
board, to mount level to
ground)
Ultrasonic
3V to 5V Buffer
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50 Pin Micro Header
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5v Reg
Compass
Connection
+ Batt -
4"
3.7"
Presentation Outline
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Project Introduction
Hardware Design
Software Design
Final Progress
Future Work
Conclusion
Questions
Software Design
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Software Block Diagram
Microcontroller Features
Software Setup
Low Level Task Breakdown
Software Design
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Software Block
Diagram
Software Design
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Microcontroller:
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8051F340 Development Kit
Similar Operation as EMAC board
 Features:
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48 million instructions per second (MIPS)
Four independent timers (T0 through T3)
Five Programmable Counter Arrays (PCA0 through PCA4)
One Serial Peripheral Interface (SPI0)
Two external Interrupts (EX0 and EX1)
Etc.
Software Design
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Software Setup:
Handle sensor reading in
interrupts
 Write low level functions for basic
operations
 Make functions to do complicated
tasks
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i.e. locate IR beacon, load bucket,
dump bucket
Software Design
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Low Level Tasks:
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Distance Measurement
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Ultrasonic sensor
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Can operate up to 20 Hz
 Small counting loop in Timer 2
 Also used as 50 ms timing source
Needs 10 us on pulse to start
 Small delay loop in Timer 2
Measure time return signal is high
 PCA2 interrupt triggered on edge transition
 Handles microsecond to cm conversion
 Sets new distance measurement flag
Software Design
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Low Level Tasks:
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Rotary Encoders
Uses EX0 and EX1 for interrupts
 Encoder period calculated based off Timer 2
 Velocity Controller
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Variable period update rates
Simple proportional controller used
Proportional-Integral (PI) controller did not work
 Low resolution encoder
 Possible initial condition problems
 Oscillations noticed with small gain
Software Design
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Low Level Tasks:
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Infrared Beacon
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External Reset Button:
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Manually read in software
Use PCA3 as interrupt
Interrupt triggers software reset
Compass
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Function to control enable/disable of compass
SPI0 handles data reception
Code reconstructs information, sets new compass reading flag
Software Design
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Low Level Tasks:
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Variable Track Drive Speed:
Function calls set motor directions
and duty cycles
 PCA’s generate Pulse Width
Modulated (PWM) signals
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Set PCA timer for 1 kHz frequency
 Best frequency found for drive
motors
 Used for 1 ms timing source
Use PCA0 and PCA1 for PWM generation
Software Design
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Low Level Tasks:
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Arm and Bucket control:
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Rotate vehicle to heading
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Function sets motors to move correct
direction
Reads corresponding sensor until pressed
Rotate fastest direction to reach the desired
heading
Turn slightly when near desired heading
until facing the right way
Remaining tasks:
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Make routines using these basic
functions plus sensor information
Presentation Outline
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Project Introduction
Hardware Design
Software Design
Final Progress
Future Work
Conclusion
Questions
Final Progress
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Sensors testing completed
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All sensors interface to microcontroller
Sensors work as desired
Exceptions:
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Ultrasonic and IR transistor when blocked by bucket
Compass when arm is near fully raised
Motor drive electronics work
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Microcontroller successfully controls speed and
direction
Heat sink added to drive circuitry to prevent
overheating
Final Progress
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Vehicle operates mostly autonomously
Can navigate between truck and load
 Loads bucket and dumps properly usually
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Small bug in location routine that causes long delay
when IR beacon too far away
 Lining up with truck is difficult due to IR beacon
spread
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Vehicle repeats task until stopped
Final Progress
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Small project difficulties
IR beacons not easy to differentiate at long
ranges
 IR beacon gives wide detection angle, and not
easy to track
 Compass/software sometimes gives wrong
orientation
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Causes alignment with bin and truck to be off
 Unknown reason for this problem
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Vehicle operation becomes somewhat random
with low batteries
Presentation Outline
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Project Introduction
Hardware Design
Software Design
Final Progress
Future Work
Conclusion
Questions
Future Work
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Add camera and computer interface
Image processing system next step in system
 Necessary for full scale operation
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Create additional autonomous vehicles
Allow cooperative interactions between
vehicles
 Could do tasks like operate truck, fill bin, etc.
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Future Work
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Replace/Upgrade Infrared Transistors
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Work on Compass/Microcontroller interface
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Difficulty tracking infrared beacons
Infrared beacon period varies with distance
Determine why compass gives wrong direction readings
Replace compass with newer model if necessary
Better Battery and Charger
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Improve operation time of vehicle
Increase linear range of drive motors
Decrease chance of overcharging battery
Future Work
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Improve Rotary Encoder Resolution
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Model Track motor and Gear Train
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Allows better velocity controller routine
Minor hardware changes
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Better measurement of linear/rotational
velocity
Active low drive signals, change ultrasonic and
IR beacon, make secure board mount in vehicle,
etc.
Create testing station with interface
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Battery-free operation, receive debug
Presentation Outline
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Project Introduction
Hardware Design
Software Design
Final Progress
Future Work
Conclusion
Questions
Conclusions
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Small scale autonomous robot works
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Bucket can be loaded without special sensors
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Need changes to system if full scale implementation
desired
Detect full bucket by period of rotary encoders
increasing past threshold
Detect nearing wall by consecutive equal distance
readings
More work to be done with project
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Full scale implementation would need image processing
More robots needed for automating an entire system
Conclusions
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Vehicle Testing Area
Conclusions
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Vehicle Operation
Conclusions
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Special Thanks To:
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Nick Schmidt for help with hardware construction and
modification
Dr. Donald Schertz for project advising, and help with
microcontroller problems
Dr. Malinowski for help with using microcontroller
Chris Mattus for ordering parts, and printing poster
board
The rest of the EE faculty for feedback about our project
Presentation Outline
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Project Introduction
Hardware Design
Software Design
Final Progress
Future Work
Conclusion
Questions
Questions
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Any Questions???
Backup Material
50 Pin Header
3.3 to 5V buffer connections
“Motor” connector
“sensor” connector