GERALD
GERALD is our first team-built robot, created for the VEX In the Zone game. It consists of a drivetrain, a mobile tray, an arm, and a claw. It's main purpose is to transport cones and mobile goals, which it does with the claw and mobile tray.
Drivetrain
The drivetrain of GERALD contains 4 omni wheels and 2 motors on each side. The mobile tray is also mounted on to the inside of the drivetrain. Though we started with 3 omni wheels on each side, we later added another to prevent GERALD from getting stuck on zone bars. We also originally included chains connecting the powered wheels to the front, but we removed them to allow for the mobile tray.
Mobile Tray
The mobile tray is a key function of our robot. It allows GERALD to obtain and transport mobile goals easily and securely.
This mechanism consists of L-channels, sprockets, and chains. The mobile tray is attached to sprockets and chains in a way that allows each tray side to simultaneously revolve. GERALD can then drive "into" a mobile goal, lower the L-channels to fit underneath, and scoop up the goal by rotating the sprockets.
Originally, we wanted to use a parallelogram design, but it took too much space and had issues moving simultaneously. Without moving simultaneously, it wouldn't be able to slide under the edge of the mobile goal.
Arm
GERALD's arm elevates the claw, allowing it to reach high areas. We chose an aluminum 6-bar design due to its stability and reduced weight. The arm also has rubber bands that help hold itself in an upright position.
For power, the arm is connected to 2 towers, each containing 2 motors. We used a 1:5 gear ratio to increase torque without a large gear stack.
Mobile Tray
GERALD's claw can pick up cones and score them on goals. It was originally made to also carry mobile goals, but due to weight problems, we decided to implement the tray instead.
Our claw has several metal teeth inside it to firmly grip the cone. Like the arm, the rubber bands are attached, though these bands help keep the claw shut.