Extendable Arm

Why:

I designed this arm to be able to extend from the regulation qualifying height of the robot to the full extension of the hooks in the design challenge for the previous year.
I used a pully system in order to make the arm faster then a typical lead screw similar to the one we used the year prior.

How:

First, I found a perfect combination of angle and arm length.

I created different sets of stages all separated by bearings to allow them to roll off of each other.
Then, I calculated the RPM needed of the motor by finding the length of the rope that would be pulled in and divided that by the circumference of the spool.
The RPM of the Mini CIM motor at 75% free speed was roughly 10 times the speed required and so I applied a 10-1 gear ratio for the Mini CIM Motor.

NOTE- the CAD is not exactly representative of the gear box to be physically used and the hex shaft size required. The hex shaft needs to be longer and the gearbox needs an encoder.

Bearings in Between Stages

Gearbox

Motor + Gearbox

Final Extension of Arm

Top View of Middle Stage

Upward View of Design

Result:

My extendable arm design was able to reach full extension of 118 inches in less then a minute.

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