How Important are Rings?

How would you get the platform to balance without having a robot on it though? I haven’t gotten my hands on the field elements yet but in the videos I’ve seen it looks like the platform tips very easily. Wouldn’t dropping a 3-4 pound goal on top of the platform cause it to tip, leading all the other goals to slide a bit in that direction too? I say “drop” because of the 2" walls on the side of the platform which make it difficult to simply place the goals up there. Again I don’t have the field, just speculating, but I feel like at least by having a robot up on the platform you can actively shift around weight in order to get it to balance. Otherwise I think you’re gonna have a hard time perfectly placing all the goals so that they counterbalance each other.

the platforms are actually quite forgiving,

you can put the goals quite far to one side and the platform stays balanced.

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It would be really nice if Vex posted something like @Golf ’s field tour. That way we could all see the individual parts of the field. Either that or a match played. Maybe next year…

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Don’t know why I remembered it being a lot wobblier than that. But even so, if you start by putting one goal to the right of the center of the platform in a way that it stays balanced (like in the video), then you can put a goal to the left of that (and it will stay balanced), but as soon as you try to put another goal to the side of either of those first 2 goals, the platform will tip since the third goal would be even farther from the platforms pivots than the first 2.
Then again there are ways to work around this, like if one bot can lift up the platform while the other bot puts a 4th goal on the opposite end to rebalance it. And this is only an issue if you’re able to get 2 neutral goals in the first place. With an odd number of mobile goals you could just start from the very center of the platform and then go adding one mogo at a time on each side, and it would probably stay balanced.

TLDR: I still have no idea what the meta will be and am just posting my thought process at this point

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True, but it is not only about the total available power - the number of degrees of freedom (i.e. how many independent actions you can perform) is also very important.

Yes, for a design where there is only one place/action that needs constant speed and power, motors are the way to go, but not for the designs that may need four independent claws - it would be very wasteful to dedicate whole motor to open and close each.

Motors cost 1/8th of your total available power, but incremental cost of adding an extra pneumatic cylinder is much lower and totally makes sense, if you only need to actuate it once or twice in a match.

Yes, there might be a way to trigger a passive claw lock, and if the ability to open and close it at will is strategically important, you can even try to make some sort of fancy power takeoff with ratchets or differentials and bring that power to the end of the rotating claw with complex geartrain, or some clever ropes and pulleys…

However, based on what I’ve seen in previous seasons, the reliability record of such complex systems is not that great.

And, also, controlling pneumatic cylinders from software is so much easier than trying to implement bump resistant mechanical AND-gate with levers.

There may be a handful of teams that can pull off this kind of mechanical wizardry, but I just cannot imagine any serious team, that made it to the dome, entrusting their fate to a Rube Goldberg machine look-alike vs something that has a working track record.

That is a very strong argument. But, if the winning strategy calls for the multiple degrees of freedom to handle multiple objects and functions, then it doesn’t matter if your robot is lightest and fastest, if it cannot fulfill the rest of the functions required to win the game (and relying on random partner to do them is iffy).

However, if you already have pneumatics, it may make sense to start with 8 motor drivetrain and shift some motors into the secondary functions after the initial sprint or as necessary, rather than dedicating motors to those functions or using ratchets and differentials (which add extra weight as well).

It is, probably, more like $400-500, because it looks like you will need 4-6 cylinders (or more) to handle variety of necessary actions in this game.

Once again, this all depends on the number and type of independent actions that are required for the winning strategy. And, as of right now, the best publicly known strategy calls for multiple small, infrequently performed, actions - which heavily favors pneumatics even if there was a one motor penalty for each air tank used.

Maybe, later in the season, somebody comes up with a better strategy. But right now it looks like the future champion robots will need to start with 6-8 motor drivetrain, potentially shift some motors out, have independent locks on multiple mogos (4), be able to lift them, and then be able to collect and score rings as well. (Rings are important, as OP says :slight_smile: )

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Not as important as you think. If this were the case, we would have seen more teams using pneumatics in the past when the rule was 8 motors + no pneumatics or 6 motors + pneumatics. There’s definitely a minimum number of degrees of freedom and I’m not sure where that number is, but power is still king.

Especially if you consider that in the past, had you decided to go 6 motors + pneumatics the extra DoF you’d gain would have diminishing returns. Since every actuation releases pressure from the system each time you actuate you have less and less force until you eventually don’t have enough force to move your mechanism.

I think you’re exaggerating what these locks would look like a little. There are lots of examples of semi-passive locks out there. Is this something any team could make? No. Is it something that only a handful of teams will be able to do? No.

Every year I’m completely blown away by the passive/semi-passive mechanisms teams come up with to make their robots fit in the sizing box, give their robot an extra actuation, etc… VRC teams are actually extremely creative in this regard, I would argue, more so than teams in other competitions.

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I think the concern is that free pneumatics (yes yes, it’s not infinite free power, but it is still a very useful and powerful system that can now be used with no penalty other than ones inherent in the system) will replace these ingenious and very limited passive actuations.

while passive mechanisms are still going to be viable and are a great way to get extra power and actuations out of a limited robot, pneumatics are undeniably a more powerful and versitile way of achieving actuations than some sort of purely passive mechanism.

Is that neccesarily a bad thing? I don’t know. But I do know that it is more expensive, which is my main issue with the free pneumatics change. It’s pretty clear what the gdc’s stance on the matter is, but for what it’s worth I’d much rather be given a choice between pneumatics and one extra motor than to choose between the superior but expensive pneumatics, or the alternative of no additional power. Which isn’t that big an issue for me personally, but I think that pneumatics simply won’t be in the budget for so many teams, and because of that they are inherently going to be more limited in terms of robot power than other teams.

Also I just thinkl balanced choices are a great way to foster thoughtful design decisions, every team could be able to come up with their choice based on their engineering process and their org’s limitations, instead of just going with the obvious “yes, more power” or perhaps “we don’t have pneumatics, and we aren’t going to buy them, I guess we’re not using them”.

And yes, pneumatics are not an all-powerful tool that will make or break a team’s season. They aren’t good at providing large-power or frequent actuations because of the limited air, but all the low-frequency actuations you can do with them will certainly make a difference in a team’s competitive ability, especially with a game like tipping point with so many possibilities for actuating robot mechanisms.

the idea of sacreficing 2 motors for pneumatics in the past few years has been laughable, not only because you’d lose a ton of available power, but because the past few games has not really had many uses for pneumatics that would be work giving up any motors for. Change up was so simple that a 4 motor robot could play it, there was no need for anything pneumatically powered at all. And tower takeover might have benefited from pneumatic actuations, perhaps with cube locks or other clever mechanisms, but it was also a very power-demanding game, and teams couldn’t afford to lose 2 motors of power.

The reason you can’t compare the tradeoff of previous years to this year is because yes, power is king. But we’ve just been given both full power from motors, and the versatility and actuations from pneumatics with no tradeoffs, and I think the effects of removing any sort of tradeoff will be largely negative, especially among teams that would rather not use pneumatics (either because of price or preference)

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But there are tradeoffs, but they’re not in the form the community is used to.

Let’s go back to FRC for a second:

  • In FRC there is no motor penalty for using pneumatics.
  • In FRC the tradeoff is having to design pneumatics into your robot, the weight of the various components, and the cost (which is far more expensive than cost in VRC because of various components FRC requires that VRC does not).
  • In FRC, there is no limit to the amount of air you can store, the number or size of cylinders you can use, and you have an on-board compressor to make sure you have enough air for an entire match. All of these should make pneumatics more attractive to teams.

However, there’s been a growing trend over the last 5-7 years where teams are choosing to NOT use pneumatics. Why?

  • Pneumatics are heavy and overall teams have been trending toward smaller and lighter robots. There’s only so much weight you can remove from a pneumatics system. At the end of the day, if you’re using pneumatics in FRC, you’re dedicating at least 5-10 lbs of your weight budget to it.
  • For many teams pneumatics are problematic. It’s very difficult to build a pneumatics system that does not leak air. These air leaks can be catastrophic if you’re relying on pneumatics for a mission critical part of your robot. You leave your pit full of air, you walk to your match, there’s a delay (maybe two) and next thing you know you’re down 10-20% of your air. Yes, you can recharge during a match, but this means you’re running an extra motor which means there’s less power from the battery available for your other motors.

@technik3k mentioned how a team with dome aspirations wouldn’t bet their season on a Rube Goldberg mechanism. Imagine betting your season on a hose not being cut straight, or a bad teflon tape job on a fitting, or a hose that got pulled out during a match.

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While in first the extra weight might be an issue, it is less of an issue in VRC. FRC has a weight limit, and VRC does not.

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While 10+ years ago, most top-tier FRC teams were pushing the weight and size limits, that’s completely reversed itself.

Now, the major design trend among the top performing teams in FRC for the past several years has been to aim to be as far below the weight and size limits as possible, to increase their acceleration times and overall mobility.

The only major hit on weight and complexity that FRC teams are taking now is implementing full swerve drives.

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This is true but frc has unlimited motors. So the more consistent power of motors for everything is used but in vrc the limit of 8 motors leaves teams restricted in how much power they have so pneumatics will be found on almost every high level robot for mogo lifts, claws, 2 speed transmissions.

Instead of releasing the max psi you can every time you instead use a pressure regulator and only do 50 psi so actuations are consistent.

But vex already required good funding to be the best of the best anyways so the pneumatics aren’t really a pay wall. All it adds is an extra layer of complexity which should make more interesting mechanisms.

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FRC has a 16 motor limit because of the pdp

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Oh, interesting. Maybe vrc could end up like frc in not using pneumatics but we will see at the end of the season.

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They don’t have unlimited motors. And in FRC not every motor is equal (even if they physically are). There are several factors:

  • The number of slots on the Power Distribution Panel (16x, if you’re running nothing else through the PDP)
  • The size of the circuit breaker behind the motor (the PDP only has 8x 40A slots and the rest can be as high as 30A). This means that if you used all the same motor, a motor on a 30A breaker has a lower ceiling than a motor on a 40A breaker.
  • The amount of power the battery can output. Motors in FRC have gotten more and more power hungry, while the battery has effectively been the same for nearly 30 years. If you ran 16x motors on an FRC robot at the same time, you will start to hit the limits of what the battery is capable of producing. Also keep in mind that the FRC control system will brownout once Vbat dips under 6VDC.

There’s a lot of technical reasons why teams would want to run pneumatics, but they’re still trending away from it.

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This is one of the most silly things I’ve read since vexlover72 was on the forum (may he Rest In Peace)

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image

X drive problems with traction wheel - #6 by 2775Josh
https://www.vexforum.com/t/x-drive-problems-with-traction-wheel-2/alt/85098/201

In our teams opinion, we believe as long as you have a dominant MOGO robot, you should be in the clear.
What we have is a wheel base that connects to a passive intake which sucks the rings into a sort of bin. As long as you get the robot on the platform at the end with 3 mobile goals, it would be competitive in a match. Take it with a grain of salt, but we think it will be a very good combo.
These are the current schematics:
6m Drive
pneumatic lift
1 motor conveyor
1 motor tipper.
If anyone has any input I’d love to hear it, especially on our idea of hoarding ring.

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I don’t think hoarding rings will be competitive, for a few reasons.

  1. Good luck making it effective. There are 72 rings
  2. RIngs can take up more space than you’d think, making it hard to hold enough to be effective
  3. You’re better off scoring them.
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That makes sense, I think I agree with your sentiment.

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I would agree that ring hoarding doesn’t seem very viable at the moment.

72 rings is a lot and in the time it’d take you to collect all the rings on the field your opponent is likely to have grabbed all that they need. Not to mention that they have a good number of match loads that are safe from your hoarding.

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