Engineering and Robotics » 2019 - FRC Deep Space

2019 - FRC Deep Space

To celebrate the 50th anniversary of the moon landing, FIRST partnered with NASA for a space theme all three robotics levels (FLL, FTC, and FRC). The FRC game "Deep Space" required the manipulation of two completely different objects at three different heights each and en endgame climb onto one of three different platforms: 3-inch, 6-inch, and 19-inch.
To attack this problem, our team created Buzz. We began with a rock-solid drive base design based on lessons learned over the past three years. We used 2"x3"x.123" 6061 aluminum square tubing for the weight-bearing sides. The drive was a 3-CIM EVO shifting gearbox from AndyMark directly driving the center wheels. The center traction wheel had a .050" drop over the two outer omni wheels. Those outer two wheels were belt-driven using 9mm HTD belts and 30-tooth pulleys. The belts and pulleys were kept protected inside the tubing. The center bearing holes were milled to exact size, and the outer shaft holes were slotted to allow for belt placement and tensioning. The outer bearings were captured in bearing blocks that bolted together. To lighten weight, we used a CNC router (X-Carve) to perforate the non-essential areas (determined via CAD simulation) in our signature honeycomb pattern. The drive train had zero failures all season, and was capable of providing robust defense.
The main focus the team selected was to place hatch panels with cargo placement as a secondary objective. To accomplish this, the students designed a rotating arm system with four arms: two weight bearing, and two to maintain parallelism. The upper arms were also perforated with a honeycomb pattern, this time with our newly converted CNC mill. The time was less than a tenth of the time needed for the router to complete the same task. The lower arms were driven by two CIM motors driving 2-stage VEX Planetary gearboxes. After testing 81:1 and 100:1 ratios, we settled on 90:1 output. That drove a chain drive that had a 12:28 sprocket ratio. This was plenty to drive the hatch/cargo mechanism at the end of the arm.
The hatch panels were collected with a simple mechanism: thin polycarbonate sheet with hook tape to catch the loop tape attached to the panels. The panels were "ejected" by three short-stroke pneumatic cylinders. A center cylinder was later added to improve the ease of collecting the panels by hooking their center hole. The final result was a robot easily capable of placing four to six panels during the game time. The cargo intake use a rolling shaft with compliant wheels. However, the mechanism proved to be less effective than the hatch panel mechanism, so it was abandoned to improve the functioning of the arms.
A climb mechanism was attempted late in the season, but there was not enough time to fully develop it. The complications it caused during game play lead us to remove it entirely.
Overall, the season was a success. Our very young and inexperienced team advanced to the finals at the Plano District Event and to the semifinals at the Dallas District Event. We were one win shy of qualifying for the Texas State Championships. These students will ALL be returning next year, and are already excited to get started on the season!