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 Conclusions Suggestions for future study

Inspiration Current StandardDesired Attributes Poor warehouse utilization Dynamic storage Warehousing is a “middle-man” business Lower labor and insurance overhead Safety drawbacksReduce 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

Purpose ♦Transfer products safely on and off shelf space Summary DOCKSHELVES

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” Initial Sample Mask Reverse First Signal Subsequent samples

Results Remote Button Algorithm Result 00x0A 10x01 20x02 30x03 40x04 50x05 60x06 Remote Button Algorithm Result 70x07 80x08 90x09 CH UP0x11 CH DWN0x12 VOL UP0x14 VOL DWN0x15

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/ODock # 1 bit3 bits1 bit3 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