Critical Design Review


1
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
2
Outline

• 2006 Game Review
• Design Concept Review
• Mechanical
• Controls

3
The Game
Game Animation
4
Design Concept Review

• Established an ordered list for gameplay
• Score balls
• Collect/Contain Balls
• Score on platform
• Defense-specific
• Push Balls

5
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-the-fly from our side of the field
• Many offensive and defensive autonomous options

6
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
• Four 3 rubber caster wheels
• Powered from main wheels
• Pneumatically raised and lowered
• Provide speeds up to 16 ft/s

7
Mechanical Ball Collection

• Two 2 PVC rollers in front of rigid back panel
• 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

8
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

9
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

10
Mechanical Ball Launching

• 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

11
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

12
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

13
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

14
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

15
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

16
Timeline Milestones

• 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

17
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_at_WPI 7 (Worcester MA)
• June 23th 24th 2005

18
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!!)