Objective Statement:

The objective of this phase of the project is to design a mechanism that will rotate the lifter, claw, and payload. This mechanism is needed in order to move the payload from our drop zone to another team's drop zone.

Design Constraints

Explicit Constraints:

• Must be gear driven by a third servo

• Servo arm must rotate at least 150 degrees during the pickup/drop off stages

• 10 inch diameter circle for base with 1/8th inch hole drilled in the center

• Circular base and drop zones are made of .75" MDF board

• Circular base and drop zones must be arranged in a polygon pattern

Implicit Constraints:

• The mechanism must rotate 140 degrees because there is a total of 9 groups

• Gears should mesh properly together and with the servo

• Must create some structure that holds servo and allows it to interface with the gear

Team Imposed Constraints:

• Use the least amount of gears possible to rotate the mechanism

• Select a gear ratio that can easily rotate the tower

Design Considerations:

The process for deciding the sizes of the gears involved multiple trials of the guess and check method. While planning the initial design, we knew the gear train would need two gears at least, a small one connected to the servo and a larger one connected to the base of the tower. We knew a smaller gear would have to be connected to the servo because the servo would turn between 150 and 180 degrees while the tower would only need to turn 140 degrees. More than two seemed unnecessary because there is a small change in the angle difference and could over complicate and over crowd the small base. We tested multiple sizes, changing the sizes in small amounts and testing ratios until there was a ratio that worked. Creating the most amount of torque possible through this gear mechanism was not a large concern because Karl Dyer explained that it does not require much torque to rotate the robot. Because of this information we chose a gear ratio that causes the servo to rotate about halfway between the required range of 150-180 degrees.

Model