End of Week 2 Strategy, Design and Build Update
Strategy
Hi folks, I hope that you’ve been having a positive build season thus far. This past week has continued to evolve our team’s understanding of the game, how we think it is likely to be played, and what role we see ourselves having in that game.
Commonalities with games from the past are always fun to discover, and many others have pointed out that the end-game climb is similar to 2013, that the center-field goal looks a little like that of 2017, and that the mechanisms required to play have a lot in common with 2020/21 and 2016. In terms of game play (autonomous, offensive scoring, defensive play, and scoring positions) I think that the game with the most touchpoints is 2014. Limited numbers of scoring objects that are team specific, but that can be interacted with by opponents, is likely to mean increased effectiveness of defensive play. Starvation strategy and keep-away will both be effective from low-level qualifiers to highest-level eliminations. The near-lack of protected space to take guaranteed shots from, and the apparent bounciness of balls in the high goal, are going to make the low goal and close-in high goal shots very effective. Blooping the balls in to either the high or low with bumpers touching the Fender very much reminds me of the use of the low-goal cube as a hard stop in the 2014 game. At all levels of play, one of the quickest and most effective things that a team could do was to slam into the wall of the cube and shoot either high or low.
I very much think that will happen in this game too, and I urge teams to worry less about (and spend less time on) creating long-range firing cannons, and more on dialing in one or two Fender shots that are more difficult to defend, and are less likely to bounce out.
With that in mind, our team is very focused on creating a ball shooter that can do just that: score from the Fender, in both the high and low. To help alleviate the possibility that backspin from a hooded flywheel will cause balls to bounce out, we are adding a top wheel to our hood. It’s possible that once we are good at the Fender shots we will try shots from a distance, but frankly that may not be feasible or even necessary. I’d rather take a guaranteed score than a risky one in this game, especially since there is a Ranking Point tied to the number of balls scored.
Design
The “S” curved ball path in continuing to evolve and will be the way the robot is built. It reduces the number of motors required to create a path, smooths out the transitions, gives us a clearer shot at the high goal from the Fender, and makes it slightly more difficult to defend a shot by blocking. We also feel strongly that intake/output on opposite ends is important for autonomous scoring as well as quickly snagging and scoring loose balls in teleop. Because climbing is a major focus of our strategy, we want to have a CoM that allows a quick movement from Mid to High and High to Traverse with as little swing as possible, and this arrangement helps with that as well.
A detail we added to this robot that isn’t super obvious is that we made our bumper rails across the sides double-wide this year, and are building them out of 1/8" thick 2x1. this gives a very solid second platform for attaching not only our bumpers, but our climber and intake 4-bar.
To answer the question above from nhos, the intake will be deployed only once, as it is on two 15-pound gas springs. The bushing is (we think) fine, since it will never see any kind of RPM and will only be moving in and out a few times. I believe the gap between the pivot mounts will be filled with polycarbonate tube standoffs, but I’m sure Thunderhex would work just as well. Thanks for the question!
One thing that we are carrying over from our design in 2020 is the extensive use of polycarbonate panels and long “columns” of polycarbonate tube that uses these extensively to create rigid 3 dimensional structures that are lightweight and easy to disassemble. I don’t think I’ve seen many other robots built this way. It worked great for us a couple years ago, I guess we will see how it works for this game! It should make it easy to create a ball path that is lightweight without tons of time spent on the router to create lightening patterns, as cool as those things are.
We are also experimenting with 3D printed (TPU) wheel treads for our aluminum 4" wheels. One of the more annoying things about running aluminum wheels is the constant drilling and screwing (or riveting) of nitrile tread. We don’t know if this will work out, but we are creating a few different tread patterns that we are stretching over the wheels with flathead screwdrivers, like bicycle tires and tire irons. This pattern ended up being too slick to use on carpet, but we are designing and printing others.
Build
My earlier complaints about the lack of phone-based customer service at Carbide3D turned out to be moot, as their email responses were fast, and got a new control panel into my hands within a day. A 20 minute swap of parts resulted in a fully functional CNC router, and by the end of yesterday nearly all the gussets for the drive base had been cut. We look forward to assembling them to the rails that the machinist team cut and milled on Wednesday, hopefully resulting in a complete drive base before the end of Saturday. It remains to be seen if we will take the extra day or two to have our powder coat sponsor paint the frame flake magenta, to go with our theme for the year.
Thanks again for staying with us. It’s been a very rewarding season so far, and a privilege to share it with y’all.
Mr. N