Low Profile Switch and Shooter Robots

FIRST General Forum
1

With the aftermath of Bag Day and the FUN’s Premiere Night, I think it’s pretty safe to say that a large quantity of the robots that we’ve seen made public are large scale robots with tall elevators that seem to be a popular design this year (to the point where many visually look the same!). Perhaps we won’t see this design to be as prevalent in the small sample size of a single district event or regional (although week 0 did have quite a few), but as reveal videos stand now elevators seem to be the most popular (although I do love the arm and arm/elevator hybrid designs that have also come out too).

I’m interested in hearing about the teams that opted to go for a different route - the smaller robots that have lower profiles but potentially powerful strategic capabilities. These are the switch and vault specialists, and those robots that shoot the cubes onto the scale.

From off the top of my head from the reveals that I’ve seen: there’s 4613’s adorably small yet mighty shooting robot, the feuding 4607 and 1836, 2609’s Vaultboy, 1902’s Pigxel, 144’s Ladder robot, and 1197.

2

3556, and 4481 will both be in Orlando with 1902 who you mentioned above

some others: 2587, 1787, 4480, 2403, 2976, and,3230,

3

2491 has one of these. If I don’t post a photo/video, check it out on the Great Northern livestream!

/shameless plug

4

I’d add my own team, but they’re on the list.

Just hoping we live up to BanTor I in effectiveness (that would be our 2016 robot).

5

We did go for the shooter and keeping the center of gravity as low as possible since there is that nasty bump on the middle of the field and you dont want to be top heavy while driving over that. Also because there will be no defence/blocking in the null territory. But the main reason they choose this route is to focus on switch and vault, but also have the capability to put one cube in the scale in autonomous/early in the game. We are playing week 1 and 2 events (Palmetto and Orlando) and we think it can be a gamechanger when your opponents aren’t that good in the scale.

We will see how it works out, i’m excited for the upcomming weeks.

6

1466 went with the low shooter design, though we expected elevators to be the more common design. Certainly the speed of getting an early cube up into the scale, low center of gravity, protected null territory, and ability to play scale or switch were major considerations. That, and a cube shooter just sounded like fun. We’d opted out of the shooting aspects of both Stronghold and Steamworks. Our practice robot has shown some promise so far, and I’ve seen more cubes than expected stacked on the scale this way. We compete at a week 1 event (Miami Valley).

7

Our team focused heavily on building within our means this year. We decided that based on our surprisingly low mentor experience and robot budget we would not be able to build a scale robot worthy of playing Saturday at champs. Our goal for the season is making division elims, and we figured there would be a place for a vault/switch robot in division elims.

With our strategic design set our strategy priority list was:
Vault
Switch
Climb (we do have a climber, it’s awesome, and it gets a shot in the video, but so far has only gotten tested on the practice robot, and will hopefully make its way onto Pigxel as the season progresses)

Extrapolating from that our robot priority list was:
Drivetrain
Intake/outtake
Cube movement mechanism (arm, elevator, conveyor, etc.)
Climber

The drive train we wanted to be strong but also fast, so we went with a pretty aggressive gear ratio spread (the entire reveal is low gear, she flies in high gear) and a 6 wheel tank drive with blue nitrile on the center for slightly improved turning (we’re also incredibly extra and do things like pick out our bumper fabric based on our strategy and role). In addition wanted a very low CG, as we knew with likely thousands of elevators this would be very valuable in a third robot who would be running vault, switch, and defense. This drove some of our next decisions.

We stumbled upon the idea of the top/bottom intake early on in build season (literally kickoff night with 2 drills, some hex shaft, and the two green compliance wheels in the KOP) and after ordering more wheels to test it eventually proved itself over the side intake being prototyped in parallel. This was very exciting because it gives us a huge acquisition zone compared to most team and enables our 3 cube switch auto. Next was the cube mover.

We had 2 main ideas for the cube move, an arm and a conveyor. An elevator seemed excessive for the task of lifting it 2 feet. From our simulation tests we had found that not having to turn around saves ~2.5 seconds per vault cycle, so symmetry and pass through transport became a must. This made the conveyor difficult, and we perused it for a few more days before it was eventually cut in favor of the simpler arm. The climber was also integrated into this, as it mounts to the arm to enable control and the drum for the climber is actually the axle around which the arm rotates.

Everything was then designed around the geometry of the arm and intake. We tested several iterations at tons of angles to try and find the best one and got it. We kept the low CG,

All of it has come together quite nicely, and we’re excited to see how competition goes, but it all comes back to wanting to build within our means, and I think we successfully did that. Now just to execute the rest.

A side note on cube shooters. I love them, and I definitely see the value in going low CG, I think they’ll dominate early regionals, but I think a division elims alliance needs at least 1 elevator for when things get dicey on the scale.

8

5806 also went with a low and fast switch and vault robot, that might be able to ahoot the scale…

We have a seperate thread with our reveal video.

9

Hello! I’m from Team 1787 and can elaborate a bit on our shooter.

Just as a background, here’s some footage of it actually shooting (since the video (https://youtu.be/gaA7lLfg85I) is more of a show of the robot.) https://imgur.com/gallery/KAQuT In our testing it shoots around 12’-14’ in an open area at max power which is more than enough for anything we need. We are flexible enough to get the scale in the high position for a whole match if need be, but our focus will be racing around cubes into both switches and even having some (safe!) contact with other robots

Shooter analysis:

[Album] Shooter analysis

The shooter has 5 hard wheels on top being controlled by one mini-CIM on each side, and then the bottom two sets on each side are controlled by another. The bottom most wheel is on a pivoting arm that will grip the cube after the wheels on it have spun up. This has allowed us to find the smallest possible time between ramping up the wheels and shooting at a desired power.

Small side note: we found a pneumatic cylinder with a 3’ stroke in the back room from a previous year’s FIRST choice and decided to use that for our climb “because we can” so that’s what’s on the back of the bot!

10

It looks like from this tweet that 4039 is going to have a low bot as well.

11

4613
610

12

We elected to build a simple pneumatic arm to shoot just into the switch, expecting the vast majority of teams to build scale capable robots, and knowing that our team probably isn’t capable of building an exceptional scalebot.

13

That or we have an octuple cascading lift :smiley:

14

We built a shooter this year for pretty much all the reasons stated above. Ultimately we knew we wouldn’t be the best scale bot in the world so we elected to build a mechanism that would get us by in lost matches scale wise and then become a very effective switch/vault bot once we max out at about 6 cubes on the scale.

15

I can speak to why 4607 chose the design that we did. Basically the initial thought process was Chief Hedgehog has a fear of high CoG elevator robots tipping over, racking their elevators and taking a significant amount of time to get everything working again. Based on what I’ve seen so far, this concern was a valid one.

The alternative ideas that were proposed included a design that took inspiration from our 2016 robot, and everybody quickly got on board with the idea. Here are some of the pros and cons that we came up with for our design:

Pros:

  • Low center of gravity
  • Efficient at the Switches
  • Ability to intake from 1 side and outtake on the other side into the Switch (efficient Death Cycles)
  • Invisible to the opposing alliance while filling the Vault
  • Can still reach the Scale and score in the Scale efficiently
  • Won’t rack up massive penalties by hitting the Scale
  • Can easily drive under the Scale when it’s lowered
  • Low CoG and other factors make it the ideal candidate for collaborating with triple climb specialists of all kinds (especially for approaching side ramp bots from the side with a lowered Scale)

Cons:

  • Probably less efficient at scoring in a losing Scale
  • Can’t outtake on opposite side of intake into the Vault
  • Visibility for our drivers could be a concern when the arm is down
  • Climbing becomes way more difficult without a tall structure to mount to

The decision was pretty clear to us after weighing the pros and cons of the design and combining them with our 2018 goals of winning an early event and playing in the playoffs at half champs. We figured this design would lend itself to being an ideal 3rd robot at champs.

The fact that it’s so efficient at the Vault is really just a factor of having a good intake and a really naturally talented driver. That wasn’t expected when when we were in the design process for Pitchfork.

16

I really like this game for a lot of reasons, its the most interesting strategic game since 2014, and I think could be one of the best games we’ve ever had. Two of the more interesting strategic parts of this game, is the time based scoring and counter scoring game element.

This made me think about this game differently, you have to think that the goal of this game is not to score more cubes than the other alliance, it’s to score them faster and earlier in the game. Building up an early lead is extremely important, if you have a lead on a switch or scale it takes 2 cubes to take back control of that element. Getting control of your switch and scale for the first half of a match makes it very hard for the other alliance to come back and win, games this year will be won early.

Building a good low shooter robot is hard, building one that can score with similar accuracy to an arm/lift bot is hard. However from what I’ve seen a shooting robot can score as fast or faster than most lifts (looking forward to see what 254/973/2056/1114/ect come up with). The tradeoff is there is a level of declining accuracy, as more cubes are scored on the scale, shooting accuracy declines (~7 cubes on the scale). But from what I’ve seen of most lift robots, they also struggle scoring on the scale once it gets filled. The elite lift robots have thought of this, and will be one of the things that separate them from the pack. Watch how 118/148/2471/etc can stack cubes on the scale and reach high to optimize the number of cubes they can score on a scale.

I’m really excited to see how this game plays out at elite levels of competition to see how high the stacks get on the scale, the beauty of this game is that owning the scale earlier in the game and counter attacking against their switch and using power ups can still win you matches if you are outgunned on the scale in the long run.