Design and Prototype/Build claw mechanism

[mckartha]

@WJiarong and @Ethancrumrine worked on a prototype claw/grabber/manipulator in the first few build weeks

They ended up:

• laser cutting some wooden arms from birch - eventually these will probably be plexiglass or milled aluminum
• cnc milling a 2"x2" square aluminum tube to pocket it and make space for bearings
• selecting a small pneumatic cylinder to actuate the arms in/out
• selecting a small Neo brushless motor to spin end-effector wheels to help grabbing cones and squares
• selecting/finding a set of bearings and chain to connect the motor and wheels
• assembling the claw/grabber so it could be tested with cones and cubes

In the end, pneumatic testing (maybe at twice expected pressure) broke the birch arms

[mckartha]