Continuing on from the reveals that we’ve been making all season, we’re revealing two of our robots for the Vex Robotics World Championships here. Each robot description is written by a different person, so the style might change a little bit. Feel free to ask questions below! Also come see our pit at worlds - we have kiwi chocolate!
http://dl.dropbox.com/u/35471757/quetzalcheese.jpg
Quetzalcoatlus
For one of our teams, we wanted our interaction robot to put all the objects from the interaction zone into our isolation zone. Quetzal was the design that we came up with to do this. It uses a 18 inch wide top sucker to pull up to ~10 objects into the robot, then has a rotating, misaligned 4-bar to lift all of them over the wall. This lift is used because it is very efficient, because none of the objects are lifted very far. Even though it only has two 393’s on the lift, it can lift about 9 pounds over its back.
In addition to this, it has two wings that pneumatically unfold, in order to have more capacity. When unfolded, the robot has a width of about ~26 inches.
Drive: 6x 269, 2x393, geared at 2:1 for speed on each side, on 2.75” wheels.
Arm: 2x393 at 1:7. Only needs elastic when lifting very large loads.
Intake: 2x296, 1:2 for torque
Wings: One pneumatic piston each side, allowing individual control.
Sensors: Quetzal has by far the least sensors of any of our college bots, using two shaft encoders, three potentiometers, and three bumpers.
Double Cheese
Double Cheese gets its name from the wedges on the front of its chassis. These allow it to drive through an isolation zone that is cluttered with lots of objects by forcing those objects upwards.
Double Cheese with Nathan Allen (Nallen01, Clean Sweep World Champion driver with 2919 and writer of AURA’s android Gateway scoring app)
Double Cheese uses an H-drive. Forward motors are four 393s (torque configuration) geared 2:1 for speed on 2.75” wheels. Strafe motors are two 269s geared 1.5:1 for speed on 2.75” wheels. These ratios are equivalent to 1.4:1 and 1:1 on 4” wheels.
The lift is a 6-bar designed to be able to score on all the 30” goals (both sides of the fence) on a college field, meaning it needs to be slightly taller than a high school 6-bar. To help achieve this, the long bar of the 6-bar offset by bolting it to the shoulder gear away from the centre. The 6-bar is also built slightly off parallel so that the ramp is at a lower angle near the bottom of its range and at a steeper angle near the top of its range.
The lift is driven by four 269 motors on a 1:7 reduction (torque) with rubber band assistance. Two 269 motors drive 30-tooth sprockets as side rollers, with a 30” ramp for a six-object capacity.
Other features include pneumatic drop-down intake rollers for descoring, and rubber band netting to prevent objects becoming stuck on the robot where they would prevent the lift from lowering.
More photos of all four of our robots at Gateway 2012 College Robots | Flickr
