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It had been the team's intention and strategy for DEWBOT XIII to be a high-performance shooter (together with good rear running capabilities and a fast, reliable climb). Alas, we did not accomplish the critical shooting goal. Our shooter was definitely middling. While very consistent in its shooting and capable of shooting consistently at up to 6 balls/s, feed issues limited us to an average 2.5 balls/s. In addition, while shooter elevation and wheel speed are adjustable,we had a limited number of pre-set shooting solutions and limited objective data on which to base such solutions.

The Shooter System comprises several interacting components:

  1. Shooter
  2. Feeder
  3. Ball Pickup
  4. Hopper


The shooter is a basic single-wheel shooter. While simple, this mechanism went through an enormous amount of testing and development, including multiple prototypes, the last few being CNC-produced.

Some key learnings:

  • A flywheel reduces the magnitude of speed reduction while shooting, but not recovery time
  • More power reduces speed recovery time
  • Holes in balls (fuel) interacting randomly with thin shooter rails randomly throw off ball trajectory
  • 6 inch wheels provide more consistency than 4 inch
  • 2 inch wide wheels provide more consistency than 1 inch wide
  • Printed guides expanding the ball contact area from narrow rails to >1/3rd circumference, thereby improving shooting consistency

Key design features:

  • PID controlled wheel speed
  • 3:1 reduction via 1-stage versaplanetary gearbox
  • Up to (3) 775 Pro drive motors
  • Adjustable shooting trajectory 60-85° from horizontal - adjustment via a quarter scale (large) servo. The servo drives a 14T gear (20 DP - 14° contact angle) which drives an 84T half gear on the trajectory hood. A 180° rotation of the servo rotates the trajectory hood by 30°.
  • Trajectory hood rotates co-axially with shooter wheel axle.

As of FRC Championship, we seem to have a shooter capable of shooting ~6 balls/s with good accuracy. We, however, are not able to feed this shooter consistently at this rate. As a result, shooting rate is erratic.


Ball Pickup