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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
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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
Summary • Concept • Behaviors • Implementation • Communication protocol • Conclusions • Suggestions for future study
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
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
DOCK SHELVES Summary Purpose♦ Transfer products safely on and off shelf space
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
Low Priority Remote control RF data link High Priority Fork RF Timer overflow Interrupts
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
IR Detector • Sony television remote (code #202)
Remote Button “3” Initial Sample Mask Reverse First Signal Subsequentsamples
RF Transceivers • Laipac TRF-2.4G • 1Mbps • Hardware CRC • Dual channel, full duplex • Two operating modes: Direct Mode and Shockburst
Stop and Wait ARQ • Error detection • Positive acknowledgment • Retransmission after timeout • Negative acknowledgement and retransmission
Header Error Control • Purpose: lost or damaged frames
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