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Originally Posted by Ogre
Don't just leave a teaser like that, spill the beans! What's missing?
I'm gonna guess something to handle the big ball.
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Good guess. The robot has a motorized (Globe) 2X ball gripper system that can be retracted back against the sides of the arm at match start and then rotated into various positions. We can potentially grab the bonus ball during autonomous with these grippers, and we can close them all the way and insert them between the goal bars to expedite big ball "descoring" when necessary.
The arm can be tilted down to horizontal if necessary. We can drive around just fine with the arm tilted up, but I can think of several situations where we'd like to drive around with it down. Appendages with rolling or sliding tips are mounted to the arm to support it while it's in the horizontal position.
A simple addition to the hook area enables the arm to pull the moveable goal when lowered to the horizontal position.
The lift system has three separate stages. The first stage is the carrier for the final two stages and is coupled to the drive base via the tilt system shafts. The second stage extends and retracts and is chain driven by two Fisher-Price motors coupled to the drill transmissions. The gripper system mounts to the top of this stage. The third and final stage is our double hook system, which extends and retracts via a chain loop connected to the Globe motor. The FP's do all the work to lift the bot up while hanging. The antibackdrive pins in the transmissions seem to do a good job of keeping the robot suspended once power is removed. The double hook connects to the main hook arm with a big honkin bolt. When the robot starts to hang, the hook separates a short distance from the main arm, and the entire robot is free to pivot using the bolt as a swivel point. This should help prevent any damage from robots banging on us while we are hanging.
The frame is welded 1" aluminum tubing. We have no active ball herding system, but an "inverted cowcatcher" designed into the frame allows us to effectively herd one or two balls at a time. This V-shaped area also aids in guiding the moveable goal when pushing it.
The transmission is last year's Technokat inspired system minus the shifting stage (no pneumatics this year for us - first time since 2000). A drill motor and a CIM motor are coupled together on each side of the robot to give us a balanced mix of speed and torque. We used Brecoflex pulleys and V-groove belt for our tread system. We found that our robot could extricate itself from a wide array of interesting situations on and around the platform.
And yes, those black tubes are indeed lightweight plastic golf club separators - they keep our coiled cords for the hook and gripper power and signal lines nice and tidy.
Aha I just noticed you're from my team.
--Petey - Petey [more] 
01-03-2004, 22:52
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