Day 2

A few concept sketches for our robot above. Starting at the top and working clockwise: 

The drive system: We decided on a differential drive system, which means one motor spins the right wheel, the other spins the left, and a caster wheel on the front. This design is simple, sturdy, and allows the robot to pivot in place, hopefully giving us greater mobility. 

A mockup for a crane, later scrapped. The idea was to have a servo at the back which operates the crane arm, and one at the front which somehow moves the claw. We decided the added weight of a servo on the end would be too much, and this idea was scrapped.

A sketch of a hydraulic crane system, using hydraulic cables and 2 syringes operated by servo motors. We eventually discarded this too, in favor of a servo motor at the front of the robot (back of the crane arm), near the other servo, which operates a pulley connected to a claw. This will press against a flat surface attached to the crane arm, and allow us to grab the pipe. 

A very rough sketch of the pulley system:

We have yet to decide how long the arm will be or how high off the base of the robot it will extend. We know that Base Height + Length * Sin(θ) has to be 12-13" to allow us to place it on the hook

The distance the arm extends horizontally will be equal to: Length * Cos(θ)

Finally, we decided to attach a scoop to the back of the robot to move the pieces into the goal. This is illustrated in the bottom right panel of the first picture.

I'll post equations for calculating how much torque needs to come from the servos to lift the heaviest goal objects later. Hopefully tomorrow we'll get the specs for the servos.