2 Roller, Pneumatic Activated, Bird Wheel

Github
Intake.java BallManager.java

Before brainstorming and designing possible intakes, a few goals were established:

1. Consistency: all balls ingressed (regardless of ball position, wear, or inflation) should take a similar path and end up in the same place.
2. Vector balls towards the center of the robot for easy indexing (if possible without sacrificing item 1 or item 6)
3. Simplicity and easy in-house machinability
4. Packages well with existing mechanisms, particularly the tower
5. Either be floppy or rigid enough to handle strong impacts and retain function
6. Intake balls at a rapid drivebase speed

Initially, many concepts were brainstormed, but majority fell into one of two categories:

1. An “over-the-bumper intake (OTB)” in which cargo passes over the bumper into frame perimeter
2. A “cutout intake” in which there is a cutout in the bumpers for cargo to pass through

Based on our design constraints (especially items 1 and 6), we concluded that a decision between these two concepts could not be made without testing in accurate conditions. Thus, we decided to design and develop prototypes for both of these concepts in parallel and compare results.

The first roller included compliant wheels, and the second roller featured 2 inch mecanum wheels that vectored the ball towards the center. Chain and sprockets were used as power transmission from the first to second roller. To replicate accurate intaking conditions, we mounted the prototype onto a drivebase with bumpers. While testing, a few conclusions were made:

1. Cargo sometimes spun or slipped against the bumpers
2. Very consistent
3. Intaked the ball quickly
4. Required constant maintenance and perfect compressions to remain consistent
5. Rougher bumper fabric ensured cargo wouldn’t slip

Our initial cutout intake prototype featured a bumper cutout, two arms made from aluminum tubing, and only one roller with mecanum wheels. We were not satisfied with the gripping ability, speed, or consistency of the intake, so we added another roller at the same height but with compliant wheels.

After similarly mounting the intake to a drivebase with modified bumpers, a few conclusions were made:

1. Very consistent
2. Shot the ball back very fast
3. Easy to machine and required almost no tuning
4. Vectored balls to the center

Based on our prototype testing and our initial design goals, we decided to continue with the cutout intake because of its simplicity, robustness, and lower overall retracted profile.

The final design consists of two rollers, the first with 2-inch compliant wheels, and the second with 2 inch mecanums and a center 4-inch compliant wheel. The rollers are powered by two BAG motors with a 3:1 gearbox and power is transmitted with pulleys and belts inside and outside the arms. The intake is retracted and extended using two pneumatic cylinders and pivots on two 1×1 uprights.