Transcript UEzMOW - University of Evansville

UEzMOW
University Of Evansville
Team:
Mark Randall Systems Design (Team Captain)
Zachariah Fuch High Level Control s
Addisu Taddes Low Level Controls
Low Level Control
Overview
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Hall Effect sensor based encoders are used to
calculate speed of motors
Each motor is connected to an H-driver which
utilizes pulse width modulation
Digital PID (Proportional, Intergral, Derivative)
controller is used to make the lawn mower move
straight.
Low Level Control
Block Diagram
Low Level Control
Results
Axis Rotation
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Converts global GPS longitude and latitude data
into localized x and y coordinates.
Waypoint Generation
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MATLAB program generates a series of
waypoints that cover the entire field.
Waypoint Navigation
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Determines if the robot needs to travel in the x
or y direction.
Tracks the appropriate coordinate and adjusts
motors velocities accordingly.
Determine if the next waypoint has been
reached and increment the appropriate index.
Power System
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2 X 12 V DC Lead Acid Batteries (24 V DC)
17 Ah
 4 hour fast charge 20 hour slow charge
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2 X 5 volt Power supplies
Stepped down from main 24 V supply
 Isolated/Unisolated
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GPS
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Trimble BD950
2cm Accuracy
Standalone, Differential, and Real Time
Kinematic (RTK)
20Hz Sample Rate
Bluetooth Radio Modem (9600 bps Full Duplex)
Obstacle Detection
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Maxbotix LV-EZ1
6-255”
Pulse width (147us/inch), analog voltage, or
serial digital output
System Design
System Design
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2 X 8 bit Micro Controllers
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Main Processor AT89c51ed2 (Atmel)
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6 X 8bit I/O Ports
8 bit data buss
1 Uart
ISP
Pre Processor
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AT89c51rd2
4 X 8bit I/O Ports
8 bit data buss
1 Uart
ISP
Hand Shaking
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Inter Processor Communication
2 way Communication
 2 X 8 bit Tristate Latches
 Interrupt Structure (Data ready/Received)
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Mechanical System
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Five 24 volt DC motors
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2 X drive motors
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Geared 60 to 1
3 X mowing blades
21” cutting width
 5800 RPM
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2 X 10.5” knobby tires
 Dim. 35” l X 26” w X 26” h
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Mechanical System
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Noise Level 85-90 db
Battery life 2-3 hours- 5400 sq ft
Results
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GPS System with < 1” Resolution
Mechanical system fulfilling all Contest
Requirement
Robot that can locate and avoid obstacles
Functional manual and remote kill switches
Robot capable of successfully navigating L
shaped field.