Robots > 2005-2006 > FRC - MegaMaid

2006 FRC Robot - Megamaid

Tasks: 

Sucks up Poof balls and shoots them into low goals.

Features:
  • Fiberglass framework
  • Two wheel drive with three-speed DeWalt transmissions
  • Intake system driven by two small CIM motors
  • Pneumatically actuated gate (off board compressor)
Autonomous: 

Spins up rollers and quickly shoots 8 to 10 balls in the low goal from the starting position.

Record:

Phoenix Regional- 

  • Record: 5-6-0 
  • Rank: 16
  • Quarterfinalists

Davis Sacramento Regional-

  • Record: 14-4-0 
  • Rank: 4 
  • Winners!

Championships-

  • Record: 3-4-0 
  • Rank: 58  
Awards:
  •  Highest Seeded Rookie (Davis Sacramento Regional)
  • Rookie Inspiration Award
  • Davis Sacramento Regional Winner

Media:

 

 

STORY OF THE MEGAMAID

The Megamaid was constructed for the 2006 FIRST game, Aim High.  This game required robots to shoot poof balls into any of three goals to get points; two low goals worth one point each and one central high goal worth three points per ball.  There were bonus points given to whichever team scored the most in autonomous mode, as well as an end game bonus for any robot that managed to scale the team’s ramp.

Concept

Given that this was our first time competing in the FIRST robotics competition, our team lacked the technical experience that most of the veteran teams had.  For this reason, we decided to play it safe and design a robot that would score only in the low goals.  After considering different methods for accomplishing this task, we settled on a four-wheeled robot that would suck up and expel the balls from the front.  In addition to this, we planned on making the robot roll it’s poof balls out at a fairly fast pace.  This would allow us to score in the low goal from a distance by bowling our balls across the field.

Initial design

At first, we thought that having a simple conveyor belt on the front of our robot would meet our requirements.  However, after some prototyping we realized that conveyor belts were more difficult to implement than we thought.  Not only did the belt like to walk off of the rollers, it also could not shoot the balls out at the speed we desired.  To work around this, the team decided to go with an alternative design; a serpentine sort of intake using four large PVC rollers and driven by two CIM motors.  Once we had filled our hopper with balls, we would reverse the rollers and open a pneumatically actuated gate to roll out all of the balls.  This design proved to be much easier to deal with, and so we got to work on constructing our robot.

Construction

Even though this was our first year, we decided to use some pretty cool construction methods to build our robot.  The greatest feature of our robot was our frame material, which consisted of pultruded fiberglass from Creative Pultrusions.  This was recommended to us by Falcon Robotics, team 842, from Carl Hayden High School.  This fiberglass material was lightweight, incredibly strong, and didn’t conduct electricity.  It was fairly easy to work with as well, although protective masks and goggles were required.

Our drivetrain was also pretty advanced for this being our first robot.  Rather than using the kit transmissions, we decided to construct several three-speed gearboxes out of DeWalt transmissions (big thanks to this whitepaper).  Four of these transmissions, powered by the small CIM motors, would drive each of the four wheels.  Our wheel choice was initially four 8” diameter, 2” wide traction wheels from IFI Robotics, but after an initial test of the drivetrain showed that we had trouble turning, we decided to place omniwheels on the back instead of the traction wheels.

Unfortunately, when we neared finishing construction of our robot we were shocked to see that it was already more than 25 pounds overweight!  With only three days left until it was time to ship, we worked fast to remove all of the weight we could.  Using the mighty Rotex Punch and a jigsaw, we put holes in everything that could afford them.  Much to our disappointment, this wasn’t enough and we also had to remove one of the drive motors from each side to make weight.  However, we finally managed to get the bot under weight, and with just half an hour to spare to drive it around before shipping.

Lessons Learned

The only real problem that our robot had during competition was its drivetrain.  Not only were we underpowered on the field, but we had too many breakdowns to count.  The DeWalt transmissions couldn’t stand up to the abuse we put them through, and we ended up breaking at least one in each of the competitions we went to.  After that experience, our team has decided never to use these things in a drivetrain ever again.

There was another fault in our drivetrain that made it pretty undesirable for competition use.  Because it was only two-wheel drive, it was very difficult to control.  In addition to this, the lack of suspension on our robot meant that we would lose traction if we were not on perfectly flat ground.  Unfortunately, our robot was also out of square to begin with, so we almost never had good traction while driving around!  As a final kicker, since we only had two drive wheels, a failure in any part of the system on either side would result in a stranded robot.  Several times we had the tread fall off our wheel, or a chain fall off, or a transmission break…  Moral of the story: don’t use a drivetrain like this for a FIRST robot!
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