Frisbee Shooters

Prototyping is an important area of growth. So, our first project in the 2021 Robotics Engineering course was to build a prototype frisbee shooter.

Spectrum Protopipe

We are using Spectrum Protopipe, designed by team 3847 Spectrum. This system uses 3D printed brackets and 1/2" PVC to quickly build and test ideas. It's inexpensive and versatile.

Our Protopipe Pieces (pipe connectors, motor brackets, etc.)

Group 1: Monday/Wednesday

2/3/2021

Group 1, Version 1

• Demonstrated proof of concept. It worked!

• Need to use stronger wheels (higher durometer) because the green wheels were visibly expanding at high speeds. This could lead to delamination and is unsafe.

• The frisbee only flew about 5-10 feet at these speeds before we became nervous about the wheels becoming unsafe.

2/10/2021

Group 1, Version 2

• Used motor brackets that had two supports to make the motors more rigid.

• Used one blue wheel (moderately stiff) and one black wheel (most stiff).

• Rigid setup was important.

• We think the green wheels would be better because they have more grip & make more contact with the frisbee. However, they are unsafe because they expand significantly at high speeds, and risk flying apart. So we decided to use stiff wheels (for safety) and increase compression of the frisbee by moving them closer.

2/24/2021

• Increased compression of frisbee.

• Experimented with wheel spacing. Wheels should be close together.

• Rigidity of entire mechanism is very important.

• All of the above adjustments led to improved results.

3/8/2021

• The Frisbee hit the target!

• Tested different wheels. We had the most success with a Banebots 4" Blue Compliant Wheel with 50A Durometer.

• MiniCIM motors at maximum speed (~6200 RPM). This wheel is rated for 2000 RPM. This presents a safety risk. We need to ensure safety by enclosing this mechanism.

• The wheels need to be at least a little soft to get a good grip on the frisbee during launch, but not too soft or you run the risk of delamination.

• Results from different wheels:

  • Banebots 4-7/8" Wheel (non-compliant) 60A Durometer: Too stiff, not enough grip on the frisbee.

  • AndyMark 4" Green Compliant Wheel 35A Durometer: Too soft, worried about safety (nervous about delamination of the wheel at high speeds).

  • AndyMark 4" Blue Compliant Wheel 50A Durometer: Good stiffness, decent backup, but the Banebots version of this wheel works better due to the geometry of the wheel.

  • AndyMark 6" White HiGrip Wheel 80A Durometer: This is the same wheel used on the KitBot chassis. Worst wheel that we tested because it had the least amount of grip on the frisbee. Even when we increased compression, it still did not grip it well enough for a decent launch.

Group 2: Tuesday/Thursday

Early prototype of Group 2

The group decided this layout would not work because the frisbee would not be given any spin. It would just be "chucked" without rotating. In order for the frisbee to fly, it would need to be launched while spinning.

Updated layout

2/25/2021

• Successful launch, proof of concept!

• Experimented with varying wheel speeds (2nd wheel faster than 1st wheel). More experimentation needed to determine if this is better than having both wheels at full speed.

• Used 3M high grip tape on the outside of the wheels to try and increase the friction between the wheel and the frisbee.

• Adjusted compression of the frisbee.