Introducing our 2014 Robot "Gunny"

Drive Train:
6-wheel belt drive using VexPro 3-CIM dual-speed transmission geared for 4.5/14.5 fps

Scoring Mechanism:
Catapult charged by modifed "Choo-choo" cam

Pickup Mechanism:
Powered wheels mounted on articulating arms.

Machine Vision:
Rasberry Pi and Custom Network Protocol.

Why this drive train?

We simulated the game with students acting as robots and it seemed both strength and speed were required from the drive train. We had good luck with the 2-CIM VexPro transmissions running 6-wheels using chain last year. So we did much the same as 2013 but with 3-CIMs and belts. Like our drive trains the past few years, the design is modular. We can pull out either side and replace it in 10 minutes or less.

Why a catapult?

Initial testing implied a possible wide range of compression in the game balls. We thought a catapult would best handle the compression variability. In 2008 FIRST Team 1296 was privilged to join Winnovation and win the Colorado Regional. At kickoff every mentor remembered Aren Hill's "choo choo" design, we never considered anything else. We built a custom sprocket with a hub that was actually a ratchet so a pawl kept the cam from back-driving. The design charged in 1.5 seconds or so, plenty fast enough to truss then shoot. Though we planned to have two shooting angles and two shooting forces (thus four different shots) we ended up with a single shot. Shooting from the fender seemed to be the only reliable spot given the crazy defense. Our drive train was so strong few opponents could stop Gunny from getting to the fender and remaining stable enough to shoot reliably.

Pickup choices...

We built a few powered pickups a few years ago and leaned towards a similar design after prototyping three different designs. The articulation allowed us to use the pickup to hold the ball while Gunny is in motion. The geometry is a little tricky but it worked out. Many refinements were inspired by the Ri3D competitions.

Our special software sauce!

Our software is custom C++ using tasks for every major function. The tasks interact using VxWorks© message queues. It makes the code that implements each function modular, less prone to error and temporal problems and easy to integrate into both autonomous and teleoperated modes of operation. Gunny's autonomous behaviors are implemented using a plain text script that we FTP to the robot as needed. We don't have to recomplie to change autonomous behaviors.

A new machine vision approach

This year we tried a Rasberry Pi, OpenCV libraries and custom code to do the "hot or not" detection. We were late getting it done but it kinda worked.

Season Summary

Gunny was pretty reliable AFTER we suffered through beefing up the cam sprocket and cam arms. We had troubles with field glitches in autonomous but fixed it during the Oklahoma Regional. And we must have replaced 20 belts (our fault, the pulleys were unecessarily small)! We made it to the quarter-finals in Dallas, the quarter-finals in Oklahoma (by losing a tied match - arghhh), won RoboReboot and made the semi-finals at TRR. The students, teachers and mentors of FIRST Team 1296 got in more practice and play than ever before and we had a ball!

Gunny has a cousin!

In a few previous years we built partially functional second robots. For the first time we built a complete duplicate robot this year. The students named it "Incognito" (because the bumpers were blank).