The arm of the robot was designed to hold a camera, but originally, its aims were much different. In the beginning, we thought of a multitude of ideas. These ranged from the arm to a bubble blower to a projector, some more possible (not to mention silly) than others.
Eventually, 2 ideas emerged, ready to be made: a laser pointer, to be the same as a finger pointing at things, and an arm, to hold things. The laser pointer was done very quickly, so work started on the arm by drawing and modeling how the arm would work. Eventually, a design kind of like a human arm was chosen, with one motor at the “shoulder”, one motor at the “elbow”, and two flat “bones” to swivel.
This didn’t work. Placing a motor at the elbow would break the arm with its weight with our current design. The solution was to make a linkage: two wires that went from the servo to the arm, letting us have the same torque but place the weight at the more stable shoulder. Here there was another problem: the wires would run into each other. After a bit more thought, the wires were moved up and down, to make them not hit each other. This design was also scrapped because the wires would eventually bend to the point where they were coming into contact with each other again. Two things were needed: higher gauge wire, and a different system.
If the arm couldn’t handle the weight of a motor, it definitely wouldn’t be able to handle the weight of picking up things, so instead, the arm would hold a camera, facing downwards. This would let the user of the robot look at things on top of a table, to get a closer look at things the robot itself wouldn’t be able to reach.
To solve this, new pieces were laser cut, and holes were cut in them to reduce the weight. The two wires that were interfering were replaced with one, to help with weight with almost no strength reduction, and it connected to a motor, to control the elbow joint from afar. This design worked, but still wasn’t strong enough to the camera.
To solve this, a plate was made. This plate would go around the motor, and would be attached to a metal bearing to help hold more weight. This allowed the shoulder to swivel while holding weight. A few decorative plastic panels were added, and then the arm was done.