PHASE 4

Rotating Mechanism

our goals

For the last phase, our objective is to create a rotation functionality for our mechanism. Using gears and another servo, we hope to produce a low rotational speed in order to keep everything tight/secure.

We will focus on finishing everything in a timely manner in order to communicate with adjacent groups. This will ensure our angles of rotation will not cause collisions during the group demonstration.

constraints

The constraints for Phase 4 are as follows:

The rotary table must be gear-driven by the third servo, and the servo must travel through at least 150° of rotation during the pickup/drop-off sequence.
Each team will receive a 10” diameter circle of 0.75” thick MDF and two drop zone boards (also 0.75” thick MDF). The circle has a 1/8” diameter hole in the center, added during the manufacturing process, that your rotary table can pivot on should you choose to use it. This piece serves as the ground and you may modify as needed drilling additional holes to anchor gears, servos, etc.
The MDF circles and drop-off boards are designed to be arranged in a polygon pattern, with the number of sides depending upon the number of groups in the class. A sample arrangement for five groups is shown the top right of Figure 3 but the interior angle must be modified based on your section.
Each mechanism must rotate 180*(N-2)/N degrees, where N is the number of groups in the class.

Design considerations

We adhered to the following during the design of the rotating mechanism:

Make the gear position adjustable for easy calibration and modification
Find a safe location for sensors so the main mechanism does not interfere with its normal function
Have a gear ratio that does not create a high amount of acceleration.

Gear train calculations

Output gear must rotate 135°
Input gear can rotate a maximum of 180°
Gear ratio of 25:32
Input gear must rotate 172.8° to achieve an output of 135°
- 135/(25/32) = 172.8°

Labeled & dimensioned 2D plan

3d rendering

final assembly

reflections on design

The final design satisfied the goals we outlined. The offset position of the sensor did increase the overall footprint of the base, however, it did not act as an obstruction to its functionality. In fact, being able to adjust its position proved to be helpful during the group demonstration, as some mechanisms did not release the test payload at a perfect parallel angle.

The final version of the mechanism could detect the payload, rotate without interfering with other mechanisms, and it was able to securely transport the payload. It could lift almost all of the other payloads, and was compatible with almost every other groups' mechanisms. Overall, we are satisfied with the simplicity, compactness, and effectiveness of the design we created.

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