Critical Design Review
WPI / Mass Academy
FIRST Team 190: Gompei and the HERD
Friday, February 17, 2006
Presented By:
Ken Stafford, Team Advisor
Chris Werner, Director of Operations
Outline
• 2006 Game Review
• Design Concept Review
• Mechanical
• Controls
The Game
Game Animation
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Design Concept Review
• Established an ordered list for gameplay:
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Score balls
Collect/Contain Balls
Score on platform
Defense-specific
Push Balls
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Final Design
• Six-wheel drive with two speeds
• Ability to get balls from the floor and human
player
• Controlled delivery to shooter device
• Ability to shoot balls into center goal on-thefly from our side of the field
• Many offensive and defensive autonomous
options
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Mechanical – Driveline/Chassis
• Driven by 4 CIM Motors through a two stage
reduction
• Six 5” rubber caster wheels
– Provide both traction and shortened wheel base
– Speeds up to 9 ft/s
• Ludicrous Speed Drive
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Four 3” rubber caster wheels
Powered from main wheels
Pneumatically raised and lowered
Provide speeds up to 16 ft/s
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Mechanical – Ball Collection
• Two 2” PVC rollers in front of rigid back panel
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Powered by mini-bike motor
19” long to provide large contact area
Hole pattern to assist in gripping of balls
Spins at 3000/1500 rpm
Provides 20% “squish” of ball
• Center deflector
– Effectively creates two “ball paths”
– Diverts balls upon entering robot
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Mechanical – Ball Sorting/Storage
• Five by four “revolver”
– Allows for quick and easy ball sorting and access
– Effectively stored in “single file”
– Approximately 25 ball capacity
• How it works
– Balls filled into two front openings
– Balls gravity-feed from opposite end
– Pneumatic “flapper” allows for
72-degree indexed rotation to occur
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Mechanical – Ball Launching
• Ball pitcher on turret to allow for 360 degree
shooting (1½ total turns)
– Driven by globe motor to CNCed Lexan sprocket
• Ability to score from 6 to 21 feet using same
release angle
– Fixed deflector angle allows wide shooting range
due to ‘flat’ trajectory
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Mechanical – Ball Launching
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Balls given backspin to “roll up” deflector
Contain pitcher mechanism at bottom
Pneumatic cylinder to lift ball into pitcher
Two 4” rubber wheels in series
– Driven by two Fisher Price motors
– First wheel at 4000 RPM;
second wheel at 7000 RPM
– Provides 20% “squish”
– Imparts exit velocity of ~10m/s
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Controls
• Controls challenges:
– Continuously keep the turret/pitcher aimed at the
center goal even while the robot is moving
– Operate all the other robot mechanisms to ease the
human operator workload
– Multiple autonomous strategies including scoring
on the center target during initial 10 sec period
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Controls – Navigation
• Distance Measurement
– CMU Camera
• Computes distance to target using color tracking and
calculating based on y-axis
• Computes horizontal offset using x-axis position
– Gear Tooth Counters
• Provide velocity information
for shoot-while-driving
• Robot Orientation
– Solid-state gyro provides heading information
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Controls – Additional Sensors
• Optical sensors
– Balls in “ready to fire” position
– Full/empty slots in revolver
• Wheel encoder
– Monitor the speed of the pitching motors to allow
for proportional integral adjustments
• Roller-follower
– Limit switch to indicate position/index of revolver
• Flapper sensor
– Detects when flapper is fully closed before revolving
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Controls – Autonomous
• Very similar to driver-operated periods
– Vision camera tracks light and determines when to
shoot
• Ability to select delays and different paths to
drive for unpredictability and compatibility
with alliance partners
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Controls – Operator Interface
• Driver controls both driveline and ball
collector
• Operator station to control ball launching
– Switch to indicate offensive/defensive periods
– Ability to fine tune the shooting vector
– Fully automated or fully manual shooting modes
• Sensor feedback to operator
– Indicator lights to show target
acquisition
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Timeline Milestones
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Jan. 7th – Kickoff
Jan. 11th – Strategy decision
Jan. 15th – Overall configuration
Jan. 27th – Preliminary Design Review
Jan. 30th – Chassis built
Feb. 5th – Driver try-outs
Feb. 7th – Mechanical subsystems built
Feb. 11th – Systems integrated
Feb. 17th – Critical Design Review
Feb. 21nd – Ship robot
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Competition Schedule
• Granite State Regional (Manchester, NH)
– March 2nd – 4th, 2006
• Florida Regional (Orlando, FL)
– March 10th – 12th, 2006
• Championship Event (Atlanta, GA)
– April 27th – 29th, 2006
• BattleCry@WPI 7 (Worcester, MA)
– June 23th – 24th, 2005
Team 190: Gompei and the HERD
http://users.wpi.edu/~first/
Questions?
• For more information visit our website at
http://www.wpi.edu/~first/
•Everyone is welcome to stop by and visit
us in the lab (Higgins 005) or at any
competition (just ask for details!!)