Elevators will probably dominate and here’s why


I’ve seen this mentioned on several threads, but I haven’t seen a specific thread for it. Essentially, teams with elevators will most likely dominate. Why? Well there’s a couple reasons. First off, teams that can’t place cargo or hatches higher than the first level are limited in the fact that they don’t have height. Although they will probably have a speed and cycle time advantage, they are severely limited. Elevators aren’t limited by height. Obviously there will be good teams that build low robots and good teams that build elevators, but the elevators will most likely prevail simply because they’re more versatile. Another thing is defense. There will be robots that play defense, plain and simple. Low robots will struggle against defensive bots because they won’t be able to maneuver above them. Some elevators will have the capability to extend and place above defensive bots. In addition, if an elevator were to double as a lift to get another robot to tier 3, they’re extremely valuable. Not all of these ideas are my opinion, as I’ve seen this across CD, but I’d like to hear what others think about this


Why are elevators better than arms?

You made an argument for robots that can place on the high goals versus those limited to the low goals. That doesn’t tell anyone while elevators are the best solution for this.


Elevators are harder to build than arms. But they can be faster and more compact


I’m not saying elevators are the best solution, I’m just summarizing what I’ve seen on different threads since kickoff. Arms are perfectly viable. I’m interested in seeing all designs that teams are able to come up with


So if arms are perfectly viable and meet all the criteria you laid out in the OP, why will elevators dominate?


They might, they might not. In the past, especially with last year’s game, elevators have been proven to be more effective. Arms can be effective, but the reliability of elevators has shown in the past. I know a lot of people reference the pink arm, which yes I agree was extremely effective, however that was a while back and the game has evolved a lot. In my experience, and from what I’ve seen on CD, elevators tend to be a more viable solution to the game


Have you considered that the reason elevators were more effective than arms in recent years is because the rules in the manual effectively outlawed arms during that time?


How so?


Nothing about your logic makes any sense at all. Let’s consider two designs based on Ri3D bots, because that’s on my mind: the Low bot similar to Snow Problem, and the High bot similar to Capital. I’m not worried about climbs so we’ll ignore that. The Low bot can potentially score 12 (8 cargo ship + 2 rocket * 2) of the 20 available scoring positions. The High bot can score in all 20. With infinite time in both design and match play, it’s obvious that the high bot would dominate.

But those are both limited. Let’s focus on match play, because there’s nothing wrong with overbuilding during the season.

There are 12 low scoring positions. Each of these takes a hatch cover and a piece of cargo (ignoring null panels and pre-scored cargo because it makes the math a bit easier) for 24 cycles required for your low robot to become useless. If you have 3 low robots on an alliance, they each need consistent cycles faster than 16.875 seconds to become useless (faster if you want to climb.) I have no doubt we’ll see this at high levels of play, but that’s a very fast average cycle time to average. Although it seems at face value that you lose the ability to score 40% of the game elements, the harder 40% is exactly as valuable as the easy 60% ignoring ranking points.

Low robots will struggle against defensive bots because they won’t be able to maneuver above them. Some elevators will have the capability to extend and place above defensive bots.

Good luck with that. A square-ish robot is about 30 inches, plus bumpers makes it impossible to place over it. And no way are you getting into that exact right position either. Shooters maybe. But those struggle against defense as well.

Not to mention all of the arguments about your more incoherent points or that a low bot will be much faster to design and build (and thus more reliable and with more practice), and will probably have faster average cycle times.

Edit: I forgot to add the closing part of my spiel

In no way is a high bot a bad idea, especially if you want to focus on getting the rocket RP. And yes, more teams will likely build high bots, because they’re paralyzed by the thought of depending on their alliance partners for getting that RP or getting the harder 40% of the points. For a lot of teams, where getting that 4.0 GPA RP in almost every match is a realistic goal, a high scoring bot is a rational and reasonable choice. Carefully consider whether you are part of this subset before committing to a design.


Most every recent “arm game,” such as last year, has made arms a more difficult and mechanically complex solution than an elevator though unnecessarily restrictive expansion limiting rules.

These are thankfully much more relaxed this year, and a single jointed arm is a much more attractive geometry than it has been for quite a while.


The combination of height needed to score and maximum extension outside of the frame perimeter made single-joint arms difficult or impossible to implement in previous years, and multi-jointed arms are often more difficult to construct and control than elevators. With the huge 30" extension limit this year, that is no longer the case. Many teams will find arms easier to implement than elevators because of this.

Additionally, control hardware and built in software have come a long way in the past few years, making PID loops easy for teams to implement. Back in 2013 when my team climbed to the top of the pyramid, PID loops were much more difficult. The only off the shelf option was WPILib, and it had some issues… we ended up having to write our own PID controller for the arm. That is not the case anymore, as the PID control can be done reliably entirely in the speed controller.


In 2018, robots were limited to extending 16 inches outside their frame perimeter. To pick up an 11 inch cube. If you wanted an arm, you had to get creative to avoid breaking that rule.
In 2017, robots couldn’t expand outside their starting dimensions at all.
In 2016, robots could only reach 15 inches outside their frame perimeter, and the primary objective didn’t require you to lift things in the air with an arm.
In 2015, the rules were a total free-for-all, but the objective favored mechanisms that stacked objects in a vertical column - e.g. elevators.
In 2014, robots weren’t allowed to elevate higher than 5 feet unless defending, and could only extend 20 inches outside their frame perimeter for a 24 inch ball. Shooters were more favorable.
In 2013, the 54 inch cylinder rule (which was revised a few times) made arms out of the question for many styles of pyramid climber. The main objective of the game involved launching frisbees through the air.
In 2012, the main objective was to shoot basketballs into a basket. A 14-inch extension limit contributed to the trend to not use an arm for delivering those balls.
2011, with an 84" diameter cylinder, was the last game that gave permissive rules which allowed teams to generally try an arm.

You could blame some of these on the game objective, and I’d say others were chosen because FIRST couldn’t think of a better method to disallow a single robot from blockading the field. Either way, it’s been a long time since FIRST had rules that encouraged arm building.


I understand that OP is summarizing arguments they have seen on CD (though I haven’t read the arguments I’ve seen as leaning to “domination”). I still disagree with the premise. Elevators that are well built and well driven will do great; I’d be surprised if less than 30% of historically top teams use an elevator like 1114’s last year. But Pink Arms are pretty likely to rock the high goals as well, and more than a few low bots will be shocking you by captaining alliances and winning events.