Difference between revisions of "DEWBOT VIII Shooter"

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1640's Shooter requirements for Rebound Rumble are:
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[[image:DB8_MM_120519_csm-26.jpg|350px|right|thumb|Ball leaving shooter at [[DEWBOT VIII Monty Madness|Monty Madness]]]]1640's Shooter requirements for Rebound Rumble are:
 
:* This is a shooter; not a dumper
 
:* This is a shooter; not a dumper
 +
:* Primarily targeting the top basket
 
:* High scoring reliability (>67%) from Key or closer
 
:* High scoring reliability (>67%) from Key or closer
 
:* Ability to feed balls to alliance scoring field from the outbounder station
 
:* Ability to feed balls to alliance scoring field from the outbounder station
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:* Automatic rangefinding & aiming
 
:* Automatic rangefinding & aiming
 
:* Maintain low CoM for bridge balancing & preventing bridge tips
 
:* Maintain low CoM for bridge balancing & preventing bridge tips
 +
 +
The Shooter system comprises:
 +
:# A fixed-geometry overshot wheeled shooter
 +
:# A tachometer to determine and thereby enable control of shooter wheel speed
 +
:# A camera for aiming
 +
:# A [[DEWBOT_VIII_Drive_Train#Drive_Modes | Drive Mode]] specifically for aiming the robot
 +
:# A narrow-beam sonor to determine range to back-board
 +
 +
==Key Technical Challenges & Statements==
 +
:* A high shooter elevation (trajectory) will be needed to score in the top basket
 +
:* High trajectory shooters shooting from the Key cannot be easily blocked (regardless of shooter height)
 +
:*
 +
 +
==Concepts==
 +
:* Wheeled shooter was the only serious concept examined (well, there was some catapult testing early)
 +
:* An overshot wheeled shooter offers the desired backspin
 +
:* To manage mass & cost, it was decided early that a decision to use pivot drive (which was subsequently made) would also become a decision to fix the shooter azimuth relative to the chassis.  If we use pivot drive, we will aim the robot; we will not use a turret to aim the shooter.
 +
:* The camera should be utilized to adjust azimuth (relative to field).  Automatic aiming preferred if (and only if) this could be demonstrated to result in higher scoring than Driver-aimed/Camera-assisted shooting.
 +
:* A narrow-cone sonar was specified to determine distance to backboard
 +
:* The shooter wheels must be speed-controlled
 +
:* The sonar or alternately the operator to supply the set-point for the shooter wheel speed
 +
 +
==Prototypes==
 +
Prototyping was limited and the final shooter closely resembled the prototype.
 +
<gallery widths=250 heights=250 perrow=3>
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Image:DB8_120111_csm-6.jpg|Assembling prototype
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Image:DB8_120111_csm-7.jpg|Testing undershot wheel configuration
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Image:DB8_120111_csm-9.jpg|Testing overshot wheel configuration
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Image:DB8_120112_csm-3.jpg|Prototype mounted on drill press platform
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Image:DB8_120114_csm-18.jpg|Testing prototype on [[DEWBOT VI]] chassis
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Image:DB8_120128_csm-12.jpg|Testing the integrated [[DEWBOT VIII Ball Collection and Storage|Lift]]/Shooter assembly prototype
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</gallery>
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 +
==Design Details==
 +
Power: Fisher Price -9015 motor with BaneBots P60 4:1 reduction gearbox directly driving a pair of 8" kitbot wheels<br>
 +
:3900 unloaded rpm (max)<br>
 +
Shooting Angle: 55° from horizontal (fixed)<br>
 +
Tachometer: Nippon-Denso E6DF motor with custom circuit<br>
 +
:Motor Gearbox, shooter wheels and tachometer are all on a common ½" 7075 Al shaft
 +
 +
==Control==
 +
 +
==Issues & Developments==
  
 
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[[Category:Robot]][[Category:DEWBOT VIII]]
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[[Category:Robot]][[Category:DEWBOT VIII]][[Category:Photo Galleries]]

Latest revision as of 00:40, 22 August 2012

Ball leaving shooter at Monty Madness
1640's Shooter requirements for Rebound Rumble are:
  • This is a shooter; not a dumper
  • Primarily targeting the top basket
  • High scoring reliability (>67%) from Key or closer
  • Ability to feed balls to alliance scoring field from the outbounder station
  • Backspin to drop into basket and provide dead landing upon feeding
  • Fast recycle; one shot per second (minimum)
  • Automatic rangefinding & aiming
  • Maintain low CoM for bridge balancing & preventing bridge tips

The Shooter system comprises:

  1. A fixed-geometry overshot wheeled shooter
  2. A tachometer to determine and thereby enable control of shooter wheel speed
  3. A camera for aiming
  4. A Drive Mode specifically for aiming the robot
  5. A narrow-beam sonor to determine range to back-board

Key Technical Challenges & Statements

  • A high shooter elevation (trajectory) will be needed to score in the top basket
  • High trajectory shooters shooting from the Key cannot be easily blocked (regardless of shooter height)

Concepts

  • Wheeled shooter was the only serious concept examined (well, there was some catapult testing early)
  • An overshot wheeled shooter offers the desired backspin
  • To manage mass & cost, it was decided early that a decision to use pivot drive (which was subsequently made) would also become a decision to fix the shooter azimuth relative to the chassis. If we use pivot drive, we will aim the robot; we will not use a turret to aim the shooter.
  • The camera should be utilized to adjust azimuth (relative to field). Automatic aiming preferred if (and only if) this could be demonstrated to result in higher scoring than Driver-aimed/Camera-assisted shooting.
  • A narrow-cone sonar was specified to determine distance to backboard
  • The shooter wheels must be speed-controlled
  • The sonar or alternately the operator to supply the set-point for the shooter wheel speed

Prototypes

Prototyping was limited and the final shooter closely resembled the prototype.

  • Assembling prototype

  • Testing undershot wheel configuration

  • Testing overshot wheel configuration

  • Prototype mounted on drill press platform

  • Testing prototype on DEWBOT VI chassis

  • Testing the integrated Lift/Shooter assembly prototype

Design Details

Power: Fisher Price -9015 motor with BaneBots P60 4:1 reduction gearbox directly driving a pair of 8" kitbot wheels

3900 unloaded rpm (max)

Shooting Angle: 55° from horizontal (fixed)
Tachometer: Nippon-Denso E6DF motor with custom circuit

Motor Gearbox, shooter wheels and tachometer are all on a common ½" 7075 Al shaft

Control

Issues & Developments

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