Phase 4

Rotation Mechanism

Phase Overview:

In this phase we will consider different designs for a gear train. Design considerations, specifications, sketches, assumptions and reasoning are all included. The final goal reached in this phase is to successfully rotate the arm mechanism as needed.

Design Constraints

Prior to constructing our gear train and base, we had to consider numerous constraints in order to satisfy the guidelines presented to us:

The rotary table must be gear driven by a third servo motor, which is capable of specific rotation so that the payload can be picked up and dropped off accordingly
Each mechanism must rotate 180*(N-2)/N degrees, where N is the number of groups in the class.
- Because there are 8 groups total in the class, the output gear must be capable of at least 135 degrees of rotation (180*(8-2)/8)

Sketch Design 1

Sketch Design 2

Sketch Design 3

Why we chose Design 1

Satisfied the necessary angle of rotation (135 degrees)
Provided the maximum amount of torque from the gear ratio
Fit within our base-plate assembly that the tower sat on

GLS Model

The image to the left is our initial GLS used to visualize the gear assembly on the base-plate of our tower, the pinion diameters are displayed as necessary.

SolidWorks Rendering

The above to the left is a rendered isometric view of our final product with all of the previous phases integrated into it. The image on the right is the physical build of the claw.

Calculations

Provided on the right are the calculations we performed to determine if our gear assembly would rotate by the required amount, and how much torque output our gear assembly had provided us.

It's worth a note that any gear ratio between 3/4 and 1 would satisfy the rotation requirement, and would provide more output torque on the gear, as the pinion would always be smaller, or;

3/4 < Gear Ratio < 1

Will provide sufficient geometry for the system.

Physical Demonstration & Reflection

The embedded video on the left showcases our claw working, with all phases integrated into a final package. While our design works as intended, there are some notes we can provide about our experience. While the gear ratio provides the most amount of torque, there is no further range of motion possible past 135 degrees, since there are assembly errors, the result is that our claw does not perfectly place the payload in the center of the drop-zone. Tweaking the gear ratio to be much closer to 1 would give us the extra motion we would need to be precise when dropping the payload.

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