Team Twelve/Final Paper
Contents |
Neither Last nor Least
Overall Strategy
At first the team was ready to score balls in the pyramid. One interesting thing to note: balls thrown over the perimeter of the field does not count as negative points. It would be unfortunate, however. In the end, throwing the balls over any wall would have been advantageous.
Mechanical design and sensors
Ball Possession: Essential Components
Last year, the rubber band roller, though not common amongst the teams, showed quick and easy success. We made a completely functional one for our Peggy (pegbot), and won Mock 1 by being excellent at collecting balls. We used a kit motor with a crude but quick motor mount to secure the roller to Peggy's wooden walls.
RUBBER BAND ROLLER - We decided to move ahead with CAD'ing the wheels for laser cutting out of acrylic. The staff had a helpful SLDWRKS file that we altered slightly (made the ridges deeper to be able to use thicker rubber bands). To keep pressure on the wheels to oppose the force of the rubber bands, we used a keyed rod to go through the centerholes, and attached shaft collars to the rubber band wheels that contained set screws. Quick note of advice. You'll have to secure things to poles. We ended up keying the rod to make one side flat and then attaching parts with set screws. This is pretty easy to make at Edgerton.
RAMP - We also had a ramp along the bottom layer of our robot, to direct balls into the mouth of the helix. That is, the ramp had pieces of cardboard that acted as walls. It started at the bottom of the rubber band roller and angled upwards in a semicircle arc until the maximum height that balls could go up. It then slanted downwards slowly to give the ball some momentum to end up in the perfect pick-up spot for the helix.
ROBOT DESIGN - All of our robot prototypes had very low robot bases, only .25" off the ground or so. This way, we did not need the ramp to collect balls (note: not bring them to the hopper, just collect them), and this way we won Seating. At some point, Hermes ate 6 balls and kept them in "herm" stomach. Goes to show: crude ball collection, paired with dependable code, can get you an easy win before the final competition.
Upwards Transport in the Robot: the Archimedes Screw
We understood that we need an internal upwards-carrying mechanism in the robot to score. The lowest scoring point was 6", so we needed a mechanism to move a ball up at least that high.
1st IDEA: PULLEY + CONVEYOR BELT - At first, we wanted to make some simple conveyor belt with sturdy metal parts which could figuratively "scrape" along the bottom of the ramp and draw up balls. We were quickly dissuaded by the staff, who told us that the winning design from last year was an Archimedes Screw
Final design: Archimedes Screw. We used a lot of different wires for making the screw, but we eventually settled on Steel welding rod (given to us by kind people at Central Machine Shop. Roxana is good at making friends.) We tried different widths of aluminum welding rod but it was too malleable.
Robot Motion: Trying out Gears, Not using them
We had a pretty simple yet sweet gear setup on our second acrylic prototype. Thanks to Mark and a beautiful lathe machine, we made a brass shaft to insert into the walls to let the middle gear spin freely. Gear count: a small bevel blue-threaded on a kit motor coupler, at 90 degrees with a freely spinning bevel on the wall, sort of randomly placed. This was in line with a white gear (provided) adapted with a set screw fit onto a .25" keyed shaft that also attached to the blue rubber wheels provided.
In the end, we dropped the gears because of stripping bevels, and the tiny bevel slowly falling off the motor shaft coupler. We remade our lower walls to accommodate large motors for high torque for the wheels. This caused "running into walls with happy abandon" to become a dangerous occurrence. Some advice: don't use gears unless you know how to.
We also had a caster I randomly found in Pappalardo lab scrounging for cotter pins, and it was a very good size for the back of the robot, however keeping it tilted forward slightly. We figured the center of mass of the robot was the 12V battery and the laptop battery, which would be placed somewhere along the back of the robot anyway, so we used it in the back.
Sensors: On How many, Placement, and Redoing the EE way too many times
Upward Motion
We had a conveyor/pulley belt idea at first. Here are some sketches:[[File:]]
However, after our with-the-staff meeting, we decided to use the Archimedes screw as our ball-lifting mechanism. Attach CADs?
Software design - H,D
Overall performance - all
Conclusions/suggestions for future teams - all! we can separate this by person
Roxana: -Organize your electronics FROM THE START. This is compulsory. Weak connections caused our robot to not really be able to run our very first match (Right motor wires were not in motor controller all the way).
-Try to make stuff/prototypes early. Anything. Make Anything Early.
-MAYBE HAVE A MECHE ON YOUR TEAM?? Although I can't say it went badly. If you've never done this stuff before, keep it all really simple. It was awesome. Even if you think you might fail at stuff, keep going. Ask for help.
-Huge thanks to all the Maslab Staff (IHOP ANYONE???), Mark B. (and the rest of Edgerton staff), Ron W. (of CSAIL), and Richard B. (and the rest of the CMS) for all the super mega awesome help. Each of you should get to choose between Donuts and Chocolate.
-Super Mega Foxy Awesome Hot Teams: Thanks to HexnetLLC (team 1) ([1]) for laser cutting our stuff the first two times and being generally wonderfully supportive and helpful. Thanks to Janky Woebot (team 7) ([2]) for keeping us oddly reassured and relaxed (whenever I soldered something, Melody was always laughing with you guys ^_^). Your robot's helix moved so fast...almost as fast as my heart fell for it. And no less thanks to all the other teams for being friendly all through this "competition".
Melody: - Split up the work at the beginning! Like, 2 builders, 2 programmers. Also, make a schedule and try to keep to it, so that you accomplish a bit of something every day. - Get Edgerton access. For almost 3 weeks, we only had one person on our team who had Edgerton access, which made things super duper slow, on the building side. But there were no other training sessions. I ended up just talking to Mark (Edgerton manager) and he let me work there, even though I wasn't officially trained. - Find someone with lasercutting access. It'll be useful when your acrylic pieces break... - Try to finish a CAD model of your robot as early as possible. - Also, if you don't know what to do, just ask the TAs. For us, especially at the beginning, we felt super lost and were a bit intimidated by them. But they're super helpful and really nice people, and we got to know some of them pretty well. - FINALIZE YOUR STRATEGY. Our team somehow didn't decide that we only wanted to score over the wall / lower level of pyramid until the very, very end, which made building very stressful. Know what you want to do. Also, even if you don't have mechanical ability, don't be afraid to aim high (literally, in our case). You'll figure things out! Also, mechEs on other teams are especially nice and helpful when you have questions.
