Key Features:

  • 2009 Kit Bot
  • Integrated motor mounts
  • Integrated bumper mounts
  • Integrated wheel mounts
  • Welded

Specs:

  • 2009 Kit Bot frame provided by FIRST
  • Two CIMs
  • Two AndyMark, GEM500 Planetary Gear Boxes
  • Driven with #25 Chain
  • 13.5:1 reduction through single gear box
  • Maximum velocity on regolith floor: 7 fps
  • 34 tooth sprockets used to drive wheels
  • Four Rover Wheels as provided by FIRST

After we decided on a robot strategy, we looked at what drive we needed to accomplish the game. The team had designed a prototype chassis in the fall of 2008 to use as a platform for the testing of polychain belt and #35 chain. We were planning on using a similar design for the 2009 game, but the extreme differences of Lunacy, namely the lack of traction we could gain from the Rover Wheels and the Regolith, forced us to look at alternatives.

What we decided on is a rectangular chassis, made of the 2009 Kit Bot aluminum C channel, and driven with a wide (37") side forward orientation. This decision was based off of three principle goals: first was the speed in which the chassis could be assembled. With little adaption needed to fabricate the components, we were able to have our drive up and running in only a few nights. In past years it took us sometimes a full week-and-a-half to have our final drive up and running. The ability to have a robot to practice with in the first week helped the team with understanding how a robot will react with this exceptionally complex playing field. Second was that the Kit frame sits much flatter than any chassis we could have made in house. Our team takes a lot of pride in our ability to weld. We have two exceptional mentors as well as a student, whom did most of the welding this year, on our team. Yet, after using the prototype drive from the fall for the first couple of nights after kick off, we noticed that it wasn't sitting perfectly flat. The physics involved in this year's game mandate that a robot must have the minimum number of contacts on the ground and that each of these wheels must have the weight evenly distributed. It was much more practical to use the Kit Bot frame then to spend many a night trying to get a custom chassis be just as effective. Third, the pre-milled holes are very efficient because they allowed us to complete the chassis very quickly, as well as correctly. Above all we wanted to have a drive train up and running as quickly as possible, and the Kit frame was the best option that we had to achieve that goal.

We now had a chassis, but we needed a drive. Most people don't treat them as synonymous. We, on the other hand, strived to make them one system and took time to decide on how to integrate the drive into the chassis. What we came up with makes for an exceptionally strong and elegant design. We have motor mounts made out of 1/8" wall aluminum that provide us with a rigid, constant, and easy connection for our GEM500 gear boxes. Bumpers, a problem for us in the past, were not mere afterthoughts, but specifically designed by using fabricated angled parts. The frame was welded into place for rigidity and weight reduction (2-3 lbs of nuts and bolts). The drive chain is powered by two AndyMark GEM500 planetary gearboxes, which give us a 13.5/1 reduction solely through the gearbox. These are both placed toward the rear of the chassis. The two back rover wheels are direct drive from these gearboxes which then connect with #25 chain to the front two rover wheels. These wheels each have a 34 tooth sprocket in which the chain sits. Using data such as wheel height (6"), reduction (13.5/1), and some motor specs we were able to calculate our max fps at 7.2 on the regolith floor.

All in all, this chassis and drive train was built from the ground up using past experience to achieve the perfect system that we needed to be competitive. It is not complex or fancy, but we get from point A to B better other bots that might have a more intricate system.