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ME72 Design Competition | Caltech MCE | Fall 2019 - Winter 2020
35th Annual ME72 Competition Winner
Collaborated with Alexei Garcia, James Douglas Walker, Mitch Watson, and Ari Rosner
Competition Guidelines
Competition Guidelines
The competition guidelines state that teams must design, build, and field three amphibious, remote-controlled robotic vehicles and battle against their opponent for control of shooting towers and a rotating center island within a 42-ft x 51-ft rectangular section of Millikan Pond. Robots must successfully navigate both land and water environments, obtain balls from dispensers, and shoot or deposit them into goals to score points.
My Role
My Role
My team of 5 undergraduates won the 2020 competition. I played a major role in designing and building two of the team's three amphibious robots: the Archimedes Screw Robot. Major design features of this robot that I contributed to include the ball handling mechanism, the Archimedes screw drive, and system integration and electronics. Leading up to competition day, I refined several mechanical issues, debugged multiple circuit issues, spent hours practicing with the robot in the competition pond. On competition day, I helped debug a drivetrain issue we had on one of the robots and was a driver for a robot that scored most of the team's points.
Ball Handling Mechanism
Ball Handling Mechanism
The ball handling mechanism was initially designed to be a conveyor belt elevator (pictured), but it was too top-heavy to maintain ballast while floating in water. This prototype was constructed with milled acrylic supports, 3D printed parts in PLA, and a 3D printed timing belt made of TPU.
With the help of another teammate, I designed and fabricated a flywheel shooter in less than 2 weeks. This final design has adjustable middle guide rails to calibrate release height and angle of the ball. The flywheel is driven by a DC motor and the structure is made of laser-cut acrylic and threaded rods. An optional deflection plate extension may be added to score into lower tower levels. The video below demonstrates the shooter's capabilities.
IMG_1897.mp4* Note: Video has sound. Video Credit: Ari Rosner.
Archimedes Screws and Base
Archimedes Screws and Base
The Archimedes screw was designed to optimize surface area and structural integrity. Its large outer diameter and small inner diameter allow for the screws to rotate and displace water with a large surface area, allowing for higher flow rates. The screws were 3D printed and chain driven by DC motors. This design had several advantages including maximized maneuverability and stability in water (can do a 360º point turn) and overall speed. The base was also comprised of Tetrix, which had precut holes that allowed for modular mechanism attachment and ease of fabrication once cut to its proper size.
Electronics
Electronics
I also programmed and constructed circuits for both robots. Each robot was powered with a 12V LiPo battery; power was distributed with a power distribution board (PDB). The 2 DC motors for the screws and the DC motor for the flywheel were controlled by Roboclaw DC motor controllers connected to an Arduino. A servomotor lever arm was used to regulate ball release from the main bucket. I wrote and tested Arduino code to control all these components through a PlayStation remote controller, including a built-in speed incrementer for the flywheel. I also waterproofed the electronic components by drilling into and waterproofing a plastic box.
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