AGV / ASRS

1
AGV / ASRS

• April 12th, 2005
• Student Names Trevor Skipp and Albert Chung
• Instructor A. A Arroyo
• University of Florida
• Department of Electrical and Computer Engineering
• EEL 5666 Intelligent Machine Design Laboratory

2
Summary

• Concept
• Behaviors
• Implementation
• Communication protocol
• Conclusions
• Suggestions for future study

3
Inspiration
Current Standard Desired Attributes
Poor warehouse utilization Dynamic storage
Warehousing is a middle-man business Lower labor and insurance overhead
Safety drawbacks Reduce the risk of personal injury
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DesignersApproach

• Divide tasks among two automated vehicles
• AGV (Automated Guided Vehicle)
• Inexpensive, small, fast, and nimble
• ASRS (Automated Storage and Retrieval System)
• Expensive, tall, slow, and bulky

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Behaviors
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Design Specifications

• Operate in a 4x8 model warehouse
• Navigation
• Obstacle detection
• Queue
• Communication
• Mechanical fork lift

7
Model Warehouse

• Shipping and receiving docks
• Transition dock
• Storage shelves

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Navigation

• Follow a high contrast line
• Cartesian coordinate system
• Knowledge of current location, destination, and
  direction

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Queue

• FIFO job processing
• Incoming pallets are marked with an age
• Outgoing pallets are delivered oldest first
• Application to food and other products that can
  expire

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Communication

• User input
• Notify that a pallet is entering the warehouse
• Request a pallet to be shipped out
• Data link between vehicles
• Assign tasks
• Determine transition dock
• Notify when a task is completed

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Simulation
DOCKS
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Purpose ? Transfer products safely on and off
shelf space
Summary
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Implementation
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Required Modules

• Fork Lift
• Power
• Motor Driver
• L.C.D.
• Sensors
• RF Transceiver

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Fork Lift (ASRS)

• Capable of lifting pallets onto a 3 tier shelf
• Screw type powered by a 200 RPM motor
• Expensive

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Fork Lift (AGV)

• One height
• Tilt type powered by a servo
• Cheap

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Interrupts

• Low Priority
• Remote control
• RF data link

• High Priority
• Fork
• RF Timer overflow

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Power

• Required voltage levels
• 3.3V Logic
• 5V Motor driver, LCD, servo
• 12V Gear head motors

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Backbone Sensors

• Line follower Optek OPB745 Reflective Object
  Sensors
• Obstacle detection Sharp GPD2D12 infrared range
  finders
• Obstacle collision Bump sensors

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Line Follower Module
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IR Detector

• Sony television remote (code 202)

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Decoding Technique
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Remote Button 3
1 0 0 0 0 1 1 0 0 0 0 0 1 1
Initial Sample
1 0 0 0 0 1 1 0 0 0 0 0 1 1
Mask
0 0 0 1 1
Reverse
0 0 0 1 1
First Signal
Subsequent samples
1 1 1 0 0
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Results
Remote Button Algorithm Result
7 0x07
8 0x08
9 0x09
CH UP 0x11
CH DWN 0x12
VOL UP 0x14
VOL DWN 0x15
Remote Button Algorithm Result
0 0x0A
1 0x01
2 0x02
3 0x03
4 0x04
5 0x05
6 0x06
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RF Transceivers

• Laipac TRF-2.4G
• 1Mbps
• Hardware CRC
• Dual channel, full duplex
• Two operating modes Direct Mode and Shockburst

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Communication Protocol
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Stop and Wait ARQ

• Error detection
• Positive acknowledgment
• Retransmission after timeout
• Negative acknowledgement and retransmission

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Header Error Control

• Purpose lost or damaged frames

Frame Check I/O Dock
1 bit 3 bits 1 bit 3 bits
----------Header------------ -----------Data-------------
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Alternating Frame Numbers
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Special Considerations

• Dynamic resynchronization
• Stations have different timeout lengths
• Lost connection
• Duplicate transmissions

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Example

• ASRS
• Places a command from the remote control onto the
  queue
• Sends command to the AGV through RF
• Sets timer and waits for an ACK
• AGV
• ACKs packet
• Echoes packet back after the job is completed
• Sets timer and waits for an ACK
• ASRS
• ACKs packet
• Updates queue

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Conclusions

• Navigation
• Communication
• Remote control
• RF protocol
• Experience
• Debugging
• Design software Eagle AutoCAD

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Suggestions for Future Study

• Sliding Window ARQ
• Larger warehouse with more shelves
• Swarm Approach Multiple AGVs for every ASRS
• Conveyor Belt robot