2020 - The Chanimal
FIRST Infinite Recharge
In 2020, COVID-19 prevented the Swampscott Currents from competing. However, 4311 was able to successfully design and build a robot, The Chanimal. The Chanimal was designed to participate in Infinite Recharge, the 2020 FRC game. In Infinite Recharge, robots gathered yellow dodgeballs - either from the ground or from openings in the driver station wall - and could shoot them into a high goal or place them into a low goal. Additional points were earned for climbing and balancing on a rotating bar, and for spinning a colorful wheel.
Robot overview
A CAD of The Chanimal may be found here.
Deciding that scoring in the high goal would be a necessary for success, the Swampscott Currents built a robot that could intake balls from the ground and shoot. To gather balls from the floor, the robot had a cutout in the front of its bumpers and a hex bar roller that drew balls in. This intake delivered the balls to a conveyor system, which used rollers to move balls toward the shooter. Once the balls arrived at the shooter, they were ejected from the robot using a single spinning flywheel. The Chanimal also had a climbing system which consisted of an elevator, a hook, and a winch. To climb, the elevator first ascended, dropping off the hook on the climbing bar. Then, two winch motors reeled in the seat belt connected to the hook, drawing the robot upward.
Strengths:
The Chanimal's flywheel shooter could shoot from up to 40 feet, allowing the robot to fire almost anywhere on the field.
The Chanimal was quite heavy, and used a powerful four-Falcon drivetrain, which would have allowed it to successfully push other robots.
The robot could climb quickly, which would have allowed it to continue scoring until the very end of the match.
Weaknesses:
The Chanimal's shooter had very little mass, and was easily slowed down by balls moving through it. The robot should have had high-inertia flywheels in order to maintain constant torque over time.
The Chanimal had a high center of gravity, making it more likely to tip over.
The conveyor's polyurethane belting frequently slipped and loosened, causing balls to jam and get stuck, making the conveyor somewhat unreliable. Belting, such as that utilized on the drivetrain, should have been employed instead.
The robot's elevator had string cables, which frequently snapped. The elevator should have been built with high-tension cable, to prevent snapping. In addition, the robot's elevator relied on gravity for downward movement, making it prone to occasional jamming.
The electronics board was rushed and not well-planned, leading to messy wiring that was hard to maintain.
Intake and conveyor subsystem
The Chanimal had a simple intake, consisting of a cutout in the bumpers and robot frame. Above the frame cutout, a hex bar attached to a motor was placed, which rotated to draw balls into the conveyor. The conveyor was made of PVC rollers connected an aluminum superstructure. Each PVC roller was made of two different sizes of pipe, cut and glued together to make grooves. Each groove held a yellow polyurethane tube, which would pull balls upward when the PVC rollers rotated. The top PVC roller was motorized, and tension from the polyurethane cables drew the other rollers along. This would pull balls toward the shooter subsystem.
Shooter subsystem
The Chanimal's shooter was made of a single, hooded flywheel driven by a Falcon 500. The hood was made of flexible polycarbonate, supported by two pressed-board walls. A metal structure was attached to the pressed board for stability, and the flywheel axle spanned across it. For shooting, two 6" stealth wheels were utilized, along with two 4" compliant wheels. The shooter had an angle of approximately 25 degrees, which allowed it to shoot from a variety of locations on the field.
Climbing subsystem
The robot's climbing subsystem had a winch, an elevator, and a hook at the top of the elevator. The elevator moved the hook up and down, allowing the robot to place it on the climbing bar. Once the hook was placed, the winche motors would wind up the seat belt attached to the hook, dragging the robot up. The elevator was made of one metal tube nested inside another. The inner metal tube had a string connected to its bottom, which threaded up to the top of the elevator shaft. When the string was pulled upward, the inner metal tube would lift up. A motor was utilized to wind up the string, allowing the elevator shaft to move linearly up and down. The hook sat on a peg at the top of the elevator, and would come loose once it hooked on the bar. After that, the elevator would retract, and the robot would begin to climb. The hook was connected to the winch motors by seat belt. To climb, the winch motors wound up the seat belt, moving the robot upward. To prevent the robot's weight from dragging the winch backward, a ratchet was utilized that only allowed the winch to turn in one direction.
