agv / asrs
DESCRIPTION
AGV / ASRS. April 12 th , 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. Summary. Concept Behaviors Implementation Communication protocol - PowerPoint PPT PresentationTRANSCRIPT
AGV / ASRSApril 12th, 2005
Student Names: Trevor Skipp and Albert ChungInstructor: A. A Arroyo
University of FloridaDepartment of Electrical and Computer EngineeringEEL 5666: Intelligent Machine Design Laboratory
Summary
• Concept
• Behaviors
• Implementation
• Communication protocol
• Conclusions
• Suggestions for future study
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
Designers’Approach
• 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
Behaviors
Design Specifications
• Operate in a 4’x8’ model warehouse
• Navigation
• Obstacle detection
• Queue
• Communication
• Mechanical fork lift
Model Warehouse
• Shipping and receiving docks
• Transition dock• Storage shelves
Navigation
• Follow a high contrast line
• Cartesian coordinate system
• Knowledge of current location, destination, and direction
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
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
IN OUT
Simulation
DOCKS
PurposePurpose♦♦ Transfer products Transfer products
safely safely on and off shelf on and off shelf
spacespace
SummarySummary
DOCK SHELVES
Implementation
Required Modules
• Fork Lift
• Power
• Motor Driver
• L.C.D.
• Sensors
• RF Transceiver
Fork Lift (ASRS)
• Capable of lifting pallets onto a 3 tier shelf
• Screw type powered by a 200 RPM motor
• Expensive
Fork Lift (AGV)
• One height• Tilt type powered by a
servo• Cheap
Interrupts
Low Priority
1. Remote control
2. RF data link
High Priority• Fork• RF Timer overflow
Power
• Required voltage levels:– 3.3V: Logic
– 5V: Motor driver, LCD, servo
– 12V: Gear head motors
Backbone Sensors
• Line follower: Optek OPB745 Reflective Object Sensors
• Obstacle detection: Sharp GPD2D12 infrared range finders
• Obstacle collision: Bump sensors
Line Follower Module
IR Detector
• Sony television remote (code #202)
Decoding Technique
Remote Button “3”
1 0 0 0 0 1 1 0 0 0 0 0 1 1
1 0 0 0 0 1 1 0 0 0 0 0 1 1
0 0 0 1 1
0 0 0 1 1
1 1 1 0 0
Initial Sample
Mask
Reverse
First Signal
Subsequent samples
ResultsRemote Button
Algorithm Result
0 0x0A
1 0x01
2 0x02
3 0x03
4 0x04
5 0x05
6 0x06
Remote Button
Algorithm Result
7 0x07
8 0x08
9 0x09
CH UP 0x11
CH DWN 0x12
VOL UP 0x14
VOL DWN 0x15
RF Transceivers
• Laipac TRF-2.4G– 1Mbps– Hardware CRC– Dual channel, full duplex– Two operating modes: Direct Mode and
Shockburst
Communication Protocol
Stop and Wait ARQ
• Error detection
• Positive acknowledgment
• Retransmission after timeout
• Negative acknowledgement and retransmission
Header Error Control
• Purpose: lost or damaged frames
|----------Header------------| |-----------Data-------------|
Frame # Check # I/O Dock #
1 bit 3 bits 1 bit 3 bits
Alternating Frame Numbers
Special Considerations
• Dynamic resynchronization
• Stations have different timeout lengths
• Lost connection
• Duplicate transmissions
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
Conclusions
• Navigation
• Communication– Remote control– RF protocol
• Experience– Debugging– Design software: Eagle & AutoCAD
Suggestions for Future Study
• Sliding Window ARQ
• Larger warehouse with more shelves
• Swarm Approach: Multiple AGVs for every ASRS
• “Conveyor Belt” robot