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					LUNAR


SECON
Senior Design II
Final Presentation
April 18th, 2008
The Team



Dr. Bryan   Ted Copeland    Bryan Reese     Theresa      Jeffrey Lorens
 Jones                                    Weisenberger




            Andrew Tigert   Khanh Bui     Ryan Sparks     Chris Daily
Approach
   Divided into 2 teams
   Team 1
     Block detection
     Navigation commands
     Environmental Sensing

   Team 2
     Block pick-up
     Block storage
     Locomotion
Presentation Outline
   Competition Overview
   Practical Constraints
   Sensors
   Locomotion
   Power
   Block Retrieval
   Onboard Communications
   Packaging
   Competition
Competition: Summary
                   Lunar mineral harvesting
                    robot
                   Color-coded blocks with
                    RFID tags
                   Collect maximum of four
                    blocks and bring them back
                    to home base
                   Final rounds head-to-head
    Competition: Court
• Red/Blue/White          Home Bases

Blocks                      Paint
X   Black Blocks
                               X


•Symmetrical Block
Placement                               6 ft
•IR Beacons (2.5kHz         Sand
and 4 kHz) on Home
Bases
•Note: Grid will not be
on the field during
competition
                           Pea Gravel

                             6 ft
Competition Approach
Presentation Outline
   Competition Overview
   Practical Constraints
   Block Detection
   Locomotion
   Power
   Block Retrieval
   Onboard Communications
   Packaging
   Competition
  Practical Constraints

Type                Name            Description
Manufacturability   Modularity      The robot must be designed as a
                                    set of subsystems that can be
                                    replaced independent of other
                                    subsystems.


Sustainability      Dependability   The robot must be sturdy enough to
                                    withstand repeated use.
Modularity

   Components are easily
    interchangeable
     Pick-up mechanism
     Batteries

     Servos

   Sensors attached to PCB
    with headers for easy
    replacement               Removable pick-up mechanism
Dependability
   Must be able to endure a 6-minute round
   Must not require any major repairs in between
    rounds
   Convert potential major problems into easily
    repairable minor problems
Dependability
   Material and construction choices
     Base

     Gripper   assembly
   Bumper
     IRSensor Placement
     Camera
Presentation Outline
   Competition Overview
   Practical Constraints
   Block Detection
   Locomotion
   Power
   Block Retrieval
   Onboard Communications
   Packaging
   Competition
Block Detection

   IR distance sensor used to identify presence of a
    block
   Subsystems:
     IRsensor
     PIC A/D converter

   3 IR distance sensors
    2  front
     1 right
Block Detection
   Check IR value when Robot was at back wall.
     Wall   Value
   When IR value > Wall Value + 30, block detected.
     Check   Color
   After block is picked up, reset Wall Value
CMUCam Color Detection
   Determines desirability of block
   Communicates Via Serial to Team1’s PIC
   Side mounted
Color Detection
   Light added to illuminate
    blocks.



     Without Light        With Light
Color Detection
   CMUCam commands
     VW, Virtual Window
     GM, Get Mean

   Block Color Detection Constraint
     Red Blocks Distinguishable ~95%
     Other colors not Distinguishable
Presentation Outline
   Competition Overview
   Practical Constraints
   Block Detection
   Locomotion
   Power
   Block Retrieval
   Onboard Communications
   Packaging
   Competition
Environmental Sensing

   Force-sensing resistors
     Stripscan be cut to width of robot
     Monitors entire span of robot’s side

   More wall contact in driving approach decreases
    error margin
Tracks


   Allows robot to maneuver over entire course
   The robot will not become stuck on pea gravel
   Coated tracks with spray-on rubber to improve traction
Drive Servos
   Speed Constraint
     Robot   is capable of maintaining 6 inches per second
   Vex Continuous Serves
     9V Servos
     Square Drive Shaft

     High Torque
Weights
   The robot was back-heavy
     Lossof traction on rocks
     Caused large amounts of drift



 Added   weights to the front
     2 one-pound bronze bars

     Centered the robot’s weight
Encoders
   U.S. Digital Rotary Encoders
     Size

     Shafttype
     Accuracy
Encoders
   Provide motor feedback and speed control
     Allows robot to drive up to 12 feet
     Error at 12 feet: 1-2 inches

   Secondary block detection
     Measures   distance to block to determine a miss
Gyroscope

               Measures turn angles
                  45º and 90º

               Collision/drift correction
               Timeouts
                  Prevent getting stuck
Presentation Outline
   Competition Overview
   Practical Constraints
   Block Detection
   Locomotion
   Power
   Block Retrieval
   Onboard Communications
   Packaging
   Competition
Power
   Constraint: operation for 7 minutes
   Worst case current draw is 4A
     Continuous servos: ~1.4A stall
     Pick-up Servos: ~1.6A peak

     Remaining electronics: 1A

   Li-Po Battery
     2150 mAh
     14.8V

     Lasts over 30 minutes at 4A
    Buck Converters

   ~90% efficiency
   Can supply constant 3A
   Initially 2 Converters used
     5V for the electronics
     6V for Pick-up servos

   9V added for Drive servos
Low Voltage Cutoff

                    Comparator circuit
                     designed to disable
                     converters when critical
                     voltage (3V per cell) is
                     reached
                    Circuit performs as
                     expected
Presentation Outline
   Competition Overview
   Practical Constraints
   Block Detection
   Locomotion
   Power
   Block Retrieval
   Onboard Communications
   Packaging
   Competition
Block Pick-up and Storage
Gripper
             Constraint requires block
              pick-up:
                At any angle

                On all three terrains

                Without sliding blocks
                 more than 4 inches
             Teflon for smooth travel
             Soft foam for better grip
Rotation

              180° servo allows precise turning
              Gears increase range to over 180°
              Ball bearings provide smooth
               rotation
Block Storage
                   Storage Constraint: 1
                   Storage Capability: 4
                     Three blocks are held in
                      the tray
                     Gripper holds the last
                      block
                     Recessed area holds side
                      blocks in place
                   Block Storage Sensor
                   FSR in left gripper
    Block Pick-Up & Storage Software
   Pulse-Code Modulation (PCM)
     20ms period
     Operates 7 servos

   Manual timing
   Physical block detection
     Rear block switch in gripper
     Force-sensing resistor

     Block switch in storage tray
    Block Pick-Up & Storage Software
   Disengage
     Ensuresblock scores
     Grips block to center

     Reverses away from block

     Reengages and picks up
      block
Presentation Outline
   Competition Overview
   Practical Constraints
   Block Detection
   Locomotion
   Power
   Block Retrieval
   Onboard Communications
   Packaging
   Competition
    LCD

   Used for debugging
   Connected to Team 2’s PIC
   Team 1 sends information for display
     Starts with a ‘t’
     Ends with a ‘\n’

     Top line of the LCD

   Team 2 displays data on the bottom
PIC-PIC Communication

   Serial Communication
    2  serial ports
     Circular buffer

   Command Processing
                checks
     Instruction

     Process command

     Send back ACK
       ACK2 for block confirmation
       ACK for turns
Presentation Outline
   Competition Overview
   Practical Constraints
   Block Detection
   Locomotion
   Power
   Block Retrieval
   Onboard Communications
   Packaging
   Competition
PCB v.1
   Initial PCB design &
    population
   PICs functional tests
   Required changes
    for next revision
PCB v.1 issues
   The PICs were too close to each other
   A few of the footprints were wrong
   Some connections were missing
PCB revisions
   Move LCD off-board
   Spread the PICs apart
   Add 9V buck converter
   Pull unused pins out to
    headers
   Add copper fill
    PCB v.2
potentiometer
                4.5V regulator



                gyroscope

  Battery
 monitoring
  circuit



                   buck
                 converter
Robot Size
   Prototype was too large      Final Version fits within 10”x10”x11”
    12”x12”x14”                   size constraint
Wire Cleanup and PCB Protection

   Wires were grouped and moved out of
    the way
   A cover was made to protect the top of
    the PCB
Bill of Materials
                              Item                        Quantity       Cost
Li-Po battery, charging equipment, & protection circuit              1   $149.66
CMUCam3                                                              1   $239.00
Servos                                                               7    173.93
Gears for Pickup Rotation                                            2     13.36
MLX90609 Gyro and breakout board                                     1    $59.95
DC-DC Converters                                                     3    $45.98
Optical Encoders                                                     2    $45.88
Tracks                                                               1    $34.98
LCD                                                                  1    $50.10
Pickup Hardware                                                      1    $66.38
24 Inch Force Sensing Resistor (FSR) Strip                           4    $72.00
80cm Sharp IR Sensors                                                3    $30.00
PCB and components                                                   1    $70.89
Total Cost




    $1,051.93
Presentation Outline
   Competition Overview
   Practical Constraints
   Block Detection
   Locomotion
   Power
   Block Retrieval
   Onboard Communications
   Packaging
   Competition
Day Before Competition
   41 registered teams
     Not   many operational teams
   Rule changes
    2  preliminary rounds
     Penalty for sliding blocks

   Final testing
     Sensor   calibration
Competition
   32 teams participated
   MSU scored a total of 200 out of possible 220
    points in preliminary rounds
   Only two teams scored more than 100pts
   MSU was the first seed in bracket
   Eighth seed in bracket scored 65pts
Special Thanks
   Dr. Bryan Jones
   Dr. Bob Reese
   MSU ECE Department
   IEEE Region 3, Mississippi Branch
Questions?
Resources
   [1] IEEE. (2007, Sept. 4). “2008 SoutheastCon
    Hardware Competition Rules,” IEEE Region 3
    Huntsville Section Web Site. [Online]. Available:
    http://ewh.ieee.org/reg/3/secon/08/documents/H
    ardware_Competition_Rules_v16.pdf

				
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