View Full Version : Stopping a Triple Balance
In the week 2 Autodesk Oregon regional only one alliance triple balanced and, even though they were the 8th alliance, ended up winning the regional. As the weeks tick by I suspect triple balancing will become the path to victory for many alliances.
Teams with a long orientation robot, like ours, would seem to be at a disadvantage here. They are more stable on the bridges in the qualification matches and double balance nicely but unless you are lucky enough to pick a couple of abnormally short robots for your alliance you aren't likely to be doing much triple balancing.
I haven't watched all the week three regionals but has a method emerged to legally slow down or stop a triple balance by an opposing alliance? Can anyone point to videos of matches where that worked out?
As a defensive player and a feeder robot, a team can just park on the wall right behind the opposing alliances bridge. Keep enough distance to eliminate a chance of a foul from transitive contact, but make it a tight squeeze so navigating to the bridge is tough. Doesn't stop it, but it does require a lot more time to pull off even a double balance with this in place.
Tommy F.
17-03-2012, 21:08
In reality, the alliance is playing defense on themselves. I can't even count how many times I've seen while watching the webcasts this week a robot tip over while trying to triple balance with their alliance. You really don't have too many options to stop a balance because of [G25].
FIRST[/I]"]
[G25]
Robots may not contact or otherwise interfere with the opposing Alliance Bridge.
Violation: Technical-Foul. If the act of Balancing is interfered with, also a Red Card and the Bridge will be counted as Balanced with the maximum number of Robots possible for that Match.
I suppose one could sit in front of the bridge on the opposing side of the field where you're not in their alley, but then you could be pushed into the bridge, which may cause a foul.
You might also be able to get balls under the opposing alliance's bridge to try and stop them from being able to get on. This should at least slow them down somewhat.
You might also be able to get balls under the opposing alliance's bridge to try and stop them from being able to get on. This should at least slow them down somewhat.
[G14]
Strategies that use Basketballs to either aid or inhibit Balancing of any Bridge are not allowed.
Violation: Technical-Foul, and counting or discounting the affected Bridge as Balanced, as appropriate.
Tommy F.
17-03-2012, 21:23
[G14]
Strategies that use Basketballs to either aid or inhibit Balancing of any Bridge are not allowed.
Violation: Technical-Foul, and counting or discounting the affected Bridge as Balanced, as appropriate.
Aha, I knew there was a rule I overlooked. Nevermind then. :)
I suppose you could trap a robot in the corner. Push them into the corner opposite your alley. Essentially box them out by angling between the corner of the fender and the wall near the opponents bridge. It effectively traps a robot in the corner assuming they don't have a drive train capable of pushing your robot out of the way sideways.
Its a 1 for 1 trade in terms of available robots on the field so your alliance would still have to out score the 2 bot balance. Ideally you could trap a good hoop scorer using the same strategy.
NOTE: I'm not positive but I believe as long as this is a 1v1 defense it would not violate [G-23]. Its still risky as you are close to the key and the bridge at times, and requires some reasonably advanced drives skill to prevent not being "juked" out enough that the opponents robot could catch a corner of your robot and spin you in place and escape.
Thad House
17-03-2012, 21:29
I saw 488 defend the triple balance in week 1. what they did is get inbetween the bridge and the robots trying to get up. it worked well, and actually stopped the triple that match.
MagiChau
17-03-2012, 21:29
Today 2054 attempted to block 910 from reaching the bridge to finish off our triple balance since 910 was trying to play defense on the other side while 1918 and us, 85 were freely allowed to go on our bridge due to 141 and 3546 already double balancing leaving 2054 to shoot 3 pointers in. 910 however managed to break free and finish off the balance barely in time (like 1 second on the clock.)
The team in the lead has a possible advantage with not needing a triple balance to win the match so they could dedicate a robot purely to defense on the bridge timing approximately before when the other alliance will attempt. Trying to time the defense is a lot more risky but frees up a robot to do something else besides block a bridge.
My 2 cents on bridge balancing.
Andrew Lawrence
17-03-2012, 21:31
I'd take a good look at the robots attempting the balance. If they haven't done it before, or aren't very successful/have a high CG, there's one great trick that will always work: Leaving them alone.
Most teams who get the triple balance do so because they practice it, or have a real good mechanism. Most teams don't get it on their first try if they don't have a mechanism for doing so.
All you need to do is sit back and watch the carnage.
Though IMO, if you can't mirror with a triple balance, you shouldn't try and disrupt their balance. The risk os too heavy, and the extra bot can be doing something good for your team (like scoring).
princessnatalie
17-03-2012, 21:49
We tried to stop the 3-bridge balance ala 488 in Alamo. They did it pretty successfully, and we just couldn't pull it off.
If you know the opposing alliance will try to triple balance since they've done so before in earlier elimination matches then, as we learned the hard way, you need to have a plan. It's very hard to make up that extra 20 points with baskets during teleop assuming both alliances have reasonable hybrid scoring.
deadman666
17-03-2012, 22:02
My team, 3487, just compeated in the bmr here in Indiana, and I was wondering if it was leagal for another robot on the blue alliance to run into our robot on purpose? I ask this because this happened to us in the simi-finals and they pentilized us and caused an electrical blow out on our robot. ::rtm::
My team, 3487, just compeated in the bmr here in Indiana, and I was wondering if it was leagal for another robot on the blue alliance to run into our robot on purpose? I ask this because this happened to us in the simi-finals and they pentilized us and caused an electrical blow out on our robot. ::rtm::I would recommend that you check the rulebook (as well as a dictionary), but in general, running into another robot is allowed.
deadman666
17-03-2012, 22:09
I would recommend that you check the rulebook (as well as a dictionary), but in general, running into another robot is allowed.
not my fault for having the worst spelling on the planet, but thank you.
:mad:
My team, 3487, just compeated in the bmr here in Indiana, and I was wondering if it was leagal for another robot on the blue alliance to run into our robot on purpose? I ask this because this happened to us in the simi-finals and they pentilized us and caused an electrical blow out on our robot
That's quite off topic and there aren't enough details in your post to respond in your case. That being said there are many places in the rules this year where one robot could cause another to get a foul by pushing them into the opposing alliance's key, alley, or bridge.
Assuming the opposing alliance is trying to load onto the ramp on their side of the field, opposite the alley, has any team tried just parking a few feet away as was mentioned earlier? Certainly the opposing alliance may try to push you into the bridge causing you to get a technical foul. My question is have they been issuing red cards for interfering with the bridge if you just sat there after the push? It would be a question to bring up in the driver's meeting.
Assuming the opposing alliance is trying to load onto the ramp on their side of the field, opposite the alley, has any team tried just parking a few feet away as was mentioned earlier? Certainly the opposing alliance may try to push you into the bridge causing you to get a technical foul. My question is have they been issuing red cards for interfering with the bridge if you just sat there after the push? It would be a question to bring up in the driver's meeting.Actually, being pushed into the bridge is not a foul unless you contact an opposing robot - see [G44]. I saw a robot try this in the finals of... Sacramento, I think? It helped a little bit, but the other alliance was ultimately able to double balance.
deadman666
17-03-2012, 22:39
I am aware but still tring to figure this site out. What happened was our robot was on the opposite side of the field close to the top of the key, but not in it. we lost connection for maybe three seconds and we were hit during that time. when we got conection back and we imedatly knew that something was wrong because we were crawling. Then we were hit again and we were done.
Originally Posted by Dale
Assuming the opposing alliance is trying to load onto the ramp on their side of the field, opposite the alley, has any team tried just parking a few feet away as was mentioned earlier? Certainly the opposing alliance may try to push you into the bridge causing you to get a technical foul. My question is have they been issuing red cards for interfering with the bridge if you just sat there after the push? It would be a question to bring up in the driver's meeting.Actually, being pushed into the bridge is not a foul unless you contact an opposing robot - see [G44]. I saw a robot try this in the finals of... Sacramento, I think? It helped a little bit, but the other alliance was ultimately able to double balance.
This is interesting
[G25] GAME
Robots may not contact or otherwise interfere with the opposing Alliance Bridge.
Violation: Technical-Foul. If the act of Balancing is interfered with, also a Red Card and the Bridge will be counted as Balanced with the maximum number of Robots possible for that Match.
[G28] GAME
Robots may not touch an opponent Robot in contact with its Key, Alley, or Bridge.
Violation: Foul; Technical-Foul for purposeful, consequential contact.
This rule applied at all times, no matter who initiates the contact, see [G44].
[G44] GAME
Generally, a rule violation by an Alliance that was directly caused by actions of the opposing Alliance will not be penalized. Rule [G28] is an exception to this rule.
[G29] GAME
An Alliance may not pin an opponent Robot that is in contact with a Court border, Fender, Barrier or Bridge for more than 5 seconds. A Robot will be considered pinned until the Robots have separated by at least 6 feet. The pinning Robot(s) must then wait for at least 3 seconds before attempting to pin the same Robot again. Pinning is transitory through other objects.
Violation: Technical-Foul
If the pinned Robot chases the pinning Robot upon retreat, the pinning Robot will not be penalized per [G44], and the pin will be considered complete.
Pinning a Robot against Basketballs that are being pushed against the Court border is an example of pinning being considered transitory.
Now, this is tricky. G44 only states that [G28] is an exception to the rule, which only involves touching the robots in contact with the bridge, not the bridge itself. [G44] does not state that [G25] an exception. That means that [G44] still applies to [G25], in that if an opposing robot causes you to touch the bridge and no robots on it, you are fine. Also, this is further clarified in the bottom part of [G29]. If a opposing robot causes you to be 'pinned' on the bridge as well, you still wont be penalized for touching bridge.
Also, to address the question of "My question is have they been issuing red cards for interfering with the bridge if you just sat there after the push?", That is addressed in [G29]. You must chase when the robot ceases to 'pin' you, so you cannot just sit there, you must actively try to move away from your contact with the bridge. Otherwise, by the rules, you will be penalized.
Now, there is another rule we have to look at
[G45] GAME
Strategies exploiting Rule [G44] are not in the spirit of the FRC and are not allowed.
Violation: Technical-Foul and Red Card
Are we really exploiting the rule? All we are doing is trying to play defense on a robot, not letting him get to the bridge. If we get pushed into the bridge, it wasnt our fault. All we were trying to do was keep them from getting to the bridge, keeping wary to not touch it by our own power.
So...Is that exploiting? I dont really know what to think!
Dale --
At Waterford District, Semifinals Match 1 (http://www.youtube.com/watch?v=uJc_ZcLiV3Y), defense was attempted, but ultimately was not successful. A blue alliance robot was parked near the red bridge to prevent the red alliance triple balance. However, all 3 red alliance robots crossed the bump and rode onto their alliance bridge from the blue side.
469 had to gingerly cross the blue key area, making sure not to contact the robot there. Once past, they were able to tip their bridge and begin the climb.
Granted, with 67's Utili-arm, the time to complete a triple balance is greatly reduced.
RyanCahoon
17-03-2012, 23:23
Teams with a long orientation robot, like ours, would seem to be at a disadvantage here. [...] unless you are lucky enough to pick a couple of abnormally short robots for your alliance you aren't likely to be doing much triple balancing.?
I agree about being at a disadvantage, but as another way of approaching the overall problem, I've seen several alliances triple balance with a couple of long robots by turning the robots once on the bridge and pushing them sideways. Requires an (preferrably wide-based) alliance partner with a good pushing drivetrain, of course.
Grim Tuesday
17-03-2012, 23:26
If all three teams can get into the protected alley, they're home free. This does, however, require two of them to have bumper traversing ability, and one of them to have bridge traversing ability. Probably good things to look for if you're going for a bridge alliance.
If all three teams can get into the protected alley, they're home free. This does, however, require two of them to have bumper traversing ability, and one of them to have bridge traversing ability. Probably good things to look for if you're going for a bridge alliance.
Couldnt they just use the coopertition bridge to cross if they couldnt cross the barrier?
Couldn't they just use the coopertition bridge to cross if they couldnt cross the barrier?
Sure but then they'd have to get past the opposing alliances key which, if defended, could cause them to incur penalties. It would certainly slow them down ... it's not foolproof.
nahstobor
18-03-2012, 00:18
Yes, you can block teams from getting on the ramp, but if all three robots can cross the barrier, their alley is a safe zone to triple balance
I just say triple balance yourself, and hope your shooters are better than theirs.
I saw 488 defend the triple balance in week 1. what they did is get inbetween the bridge and the robots trying to get up. it worked well, and actually stopped the triple that match.
Credit for that strategy belongs with 2468, however. They did the same against that alliance in the quarter-final and it was fairly effective. The missing piece, in their case, was that they didn't have a scoring machine as powerful as 118 to drive up their score while they played defense like we did.
In the vein of "the best defense is a better offense", you defend a triple balance by putting up your own triple -- more quickly.
The downside of defending a scenario where a bot already is poised at a floored bridge end and getting shoved into him for a red card is pretty much a "one move win" for the shoving alliance. It can't be worth it.
When I posted earlier I realized that I didn't say that we implemented parking in front of the bridge while playing defense. We have 4 wheels planted at all times, so moving us sideways is nearly impossible. We parked about 4 feet from the bridge and made it so the other team would have to come in and turn or come from the other side of the field through their alley. The problem with our strategy is that it only worked once. As soon as the opposing alliance saw the plan, they just crossed the bump and went in through their alley. But that first time, it sure did slow them down.
bhsrobotics1671
18-03-2012, 14:37
You could park in front of the bridge then have your battery fall out or become disabled, therefore not give up any penalties but still block the ramp. Happened to us :(
You could park in front of the bridge then have your battery fall out or become disabled, therefore not give up any penalties but still block the ramp. Happened to us :(
I find it hard to imagine there isn't a rule that would allow the refs to give you a red card for doing that intentionally.
bhsrobotics1671
18-03-2012, 14:45
I find it hard to imagine there isn't a rule that would allow the refs to give you a red card for doing that intentionally.
The ruling on the field was that they went and parked a foot or so away from the bridge. As we tried to approach the bridge, we nudged them into the bridge. The field crew was all in agreement that sometime between them sitting there, us nudging them, and before they made contact with the bridge that they lost their battery and were therefore "disabled". Since they were disabled, they could not get any penalties. It seemed to just be really bad luck on our end.
Yankeefan181
18-03-2012, 14:47
I saw 488 defend the triple balance in week 1. what they did is get inbetween the bridge and the robots trying to get up. it worked well, and actually stopped the triple that match.
I saw this match too, they were extremely effective at pushing the third robot into the fender and keeping them away from the bridge. Here's video
http://www.thebluealliance.com/match/2012stx_sf1m2
The strategy is to keep the third robot away from the bridge, while avoiding penalties. It sounds difficult, but it can be done, as seen here. Kudos to 488 and their alliance partners for putting together a smart strategy like that in week 1.
Hmm. At hatboro the heas ref told us that even if your robot becomes disabled, you are still eligible to have penalties on you.
Man, the guy in that match video is REALLY enthusiastic!
bhsrobotics1671
18-03-2012, 15:02
Hmm. At hatboro the heas ref told us that even if your robot becomes disabled, you are still eligible to have penalties on you.
I have not found a rule to disagree with your statement. Could someone please point me to the rule that says if your robot is disabled then you cannot get any penalties?
GaryVoshol
18-03-2012, 17:30
Beside committing fouls, a dead robot can also score points.
Nate Laverdure
18-03-2012, 17:44
I have not found a rule to disagree with your statement. Could someone please point me to the rule that says if your robot is disabled then you cannot get any penalties?
This rule was last seen in 2010.
<G27> Disabled ROBOTS and PENALTIES – If a ROBOT becomes unsafe (e.g. the ROBOT begins to smoke, the battery falls out, etc.), it may be disabled by pressing the E-Stop Button in the corresponding Player Station, per Rule <S03>. ROBOTS that are disabled in this manner cannot incur further PENALTIES nor can they earn additional points.
I saw this match too, they were extremely effective at pushing the third robot into the fender and keeping them away from the bridge. Here's video
http://www.thebluealliance.com/match/2012stx_sf1m2
The strategy is to keep the third robot away from the bridge, while avoiding penalties. It sounds difficult, but it can be done, as seen here. Kudos to 488 and their alliance partners for putting together a smart strategy like that in week 1.
This is essentially what I was saying earlier. At about the 1:45 mark you can see 488 push 922 into the corner like i was talking about. The difference is I believe with skillful driving you can essentially trap them there by forcing their driver to use less space to maneuver around you.
I have not yet come up with a way to stop a triple balance. However there might be other ways to work around this strategy.
Lets say in autonomous mode both teams get nearly the same amount of points. Once teleop starts, i noticed that if you ball starve the other alliance by having one robot continuously shooting balls into their zone while the other one or two robots score repeatedly. This works very well because this forces the other alliance that can triple balance to have a much lower score. This means you will be by far ahead going into the balancing stage. This makes up for the 20 points between their triple balance and your double balance.
Just my thoughts.
So we dont believe there is a way to really defend if all robots are going onto the bridge from the side of the field on their alley?
George Nishimura
18-03-2012, 19:22
You have to block them from getting to the alley.
Coach Norm
18-03-2012, 19:32
Credit for that strategy belongs with 2468, however. They did the same against that alliance in the quarter-final and it was fairly effective. The missing piece, in their case, was that they didn't have a scoring machine as powerful as 118 to drive up their score while they played defense like we did.
Thanks Madison for the kudos for our attempt to block the triple balance.
Our plan was to have 2969 go do the blocking of the bridge while we,2468 played defense on 148 and allowed 245 to stay at home and score. 2969 was having difficulty moving so we went to block the bridge. We stayed as long as I thought we could and still have time to bet on the bridge to balance with 245 but we ran out of time. Our original plan was to begin the balance at 45 seconds left. If we had gotten the balance, we would have won the match. you can see the match here.
I still believe it is a viable strategy to prevent the triple balance. We had even discussed blocking the barrier so that the opposing alliance had to use the coopertition bridge or go the long way around thus taking extra time to get there.
http://www.thebluealliance.com/match/2012stx_qf2m3
I must say, this is my rookie year and all this strategy stuff, especially defense, is really interesting. It seems bridge defending is a very effective strategy if you can be careful, and be in the right place at the right time.
While they were balancing, it seems a foul was called on the red alliance. Can someone tell me what that was for?
EDIT: Oh, I guess that was just the announcer making a mistake.
I must say, this is my rookie year and all this strategy stuff is really interesting
I found this year to be one of the more difficult years for scouting, because of the (somewhat) heightened difficulty with shooting, and the importance balancing with the bridges. In addition, the cooperation bridge was an freakin' huge wrench thrown into a lot of teams' plans.
Last year and 2010 was pretty easy in terms of functions required, as you only needed two defining actions in order to win the regional (For 2010, it was kicking and raising yourself up on the towers, while 2011 was being able to put tubes on the wall and having a fast minibot.)
If you want to be able to defense OR balance, you need high traction.
I found this year to be one of the more difficult years for scouting, because of the (somewhat) heightened difficulty with shooting, and the importance balancing with the bridges. In addition, the cooperation bridge was an freakin' huge wrench thrown into a lot of teams' plans.
Last year and 2010 was pretty easy in terms of functions required, as you only needed two defining actions in order to win the regional (For 2010, it was kicking and raising yourself up on the towers, while 2011 was being able to put tubes on the wall and having a fast minibot.)
If you want to be able to defense OR balance, you need high traction.
Well our team is using pneumatic tires, so this might work for us! This is cool...
ThirteenOfTwo
18-03-2012, 23:29
If you want to be able to balance, you need high traction.
Oh? All of the effective balancing alliances that I've seen have consisted of two or three teams--one or two that lower the bridge and get on, and one that pushes them up to balance. Only this last robot needs to have high traction...
kjmccarx
19-03-2012, 00:51
Sure, the strategy with having one team push up another robot or two works great. But only if two or more of the robots have short drive bases.
Our team has a robot that has high traction wheels. Our bot can make it up the bridge, and push people up with no problem - but we are a long robot. Because we're long we can't triple balance with ease. In the quarter finals in at the Autodesk Oregon regional we were beat by the only alliance that could triple balance. In such a situation it would have been necessary to have two of our alliance partners balance, while one of us defends the opposing alliance from getting the triple balance.
Has anyone seen a strategy that could prevent even ONE of the robots from getting on the bridge to turn a 3x balance into a 2x balance? This would make the final outcome of the match come down to the number of baskets - rather than only the team that can make a 3x balance.
ThirteenOfTwo
19-03-2012, 03:28
Has anyone seen a strategy that could prevent even ONE of the robots from getting on the bridge to turn a 3x balance into a 2x balance? This would make the final outcome of the match come down to the number of baskets - rather than only the team that can make a 3x balance. Well, you could do what 118's alliance did and ram the third robot across the field, but that rarely works out perfectly. If you played your cards right, you could make sure that you don't have to face a triple balancing alliance, or you could make one yourself.
I love Rebound Rumble if only because it penalizes teams who choose to use the most common drive train configuration in FRC.
Oh? All of the effective balancing alliances that I've seen have consisted of two or three teams--one or two that lower the bridge and get on, and one that pushes them up to balance.
You are correct.
Only this last robot needs to have high traction...
Not quite.
I'm assuming that you are talking about double/triple balancing (if it was singular, then yes, the robot does not necessarily need high traction). From what I've seen in balancing, it usually comes down to the robots on either end. If you're pushing up two robots with something like mecanum, then what will you do when the bridge tips over to the other side? Back up slowly and risk tipping over the robot on the other end of the bridge (which I've seen was extremely likely) and lose the triple balance?
ThirteenOfTwo
19-03-2012, 17:49
Not quite.
I'm assuming that you are talking about double/triple balancing (if it was singular, then yes, the robot does not necessarily need high traction). From what I've seen in balancing, it usually comes down to the robots on either end. If you're pushing up two robots with something like mecanum, then what will you do when the bridge tips over to the other side? Back up slowly and risk tipping over the robot on the other end of the bridge (which I've seen was extremely likely) and lose the triple balance?
Many of the more effective triple balancers have robots with special attachments to help them balance. A mecanum, for instance, might have a "stinger" to stop the bridge from tilting too far in the other direction. Depending on the angle of the bridge I could definitely see a low-traction drive like a mecanum having the force to slowly push a higher-traction robot.
You're correct, though, that lower traction certainly would make balancing harder. Does anyone have video of a high-traction and low-traction combo trying to balance?
pfreivald
19-03-2012, 19:08
You're correct, though, that lower traction certainly would make balancing harder. Does anyone have video of a high-traction and low-traction combo trying to balance?
http://www.thebluealliance.com/match/2012roc_qm46 is 578 and us making the double balance look easy. (See the 2:00 minute mark). We look like mecanum, but we've got our traction wheels deployed for the bridge-work -- 578 is KoS so they're not exactly low traction, but they're geared fast with 8" wheels.
I saw some team talking about ramming the opposing alliance's bridge, WHEN BALANCED, in order to throw it off.
Essentialls, incur the small penalty put prevent the opponent from gaining 40 pts.
Not in the spirit of gracious professionalism at all, but is it legal?
I saw some team talking about ramming the opposing alliance's bridge, WHEN BALANCED, in order to throw it off.
Essentialls, incur the small penalty put prevent the opponent from gaining 40 pts.
Not in the spirit of gracious professionalism at all, but is it legal?
This is a foul you don't want to take. Don't even think about it!
[G25]
Robots may not contact or otherwise interfere with the opposing Alliance Bridge.
Violation: Technical-Foul. If the act of Balancing is interfered with, also a Red Card and the Bridge will be counted as Balanced with the maximum number of Robots possible for that Match.
gyroscopeRaptor
19-03-2012, 19:43
I saw some team talking about ramming the opposing alliance's bridge, WHEN BALANCED, in order to throw it off.
Essentialls, incur the small penalty put prevent the opponent from gaining 40 pts.
Not in the spirit of gracious professionalism at all, but is it legal?
This was done at Alamo inadvertently, but led to the largest score penalty in FIRST: 49 points.
[G25]
Robots may not contact or otherwise interfere with the opposing Alliance Bridge.
Violation: Technical-Foul. If the act of Balancing is interfered with, also a Red Card and the Bridge will be counted as Balanced with the maximum number of Robots possible for that Match.
It would actually count for the maximum number of robots balanced, and give the technical-foul as well. Essentially once the alliance sees the red card they can all drive off the bridge and go back to scoring because they're guaranteed the maximum number of robots balanced even if they aren't even touching the bridge anymore.
You're correct, though, that lower traction certainly would make balancing harder. Does anyone have video of a high-traction and low-traction combo trying to balance?
Many of our balances were with lower traction robots -- including those with mecanum wheels.
We ask that our partners put light pressure on our robot at all times. They won't push us and we can regulate their movement with our robot. It makes balancing very easy.
Many of the more effective triple balancers have robots with special attachments to help them balance. A mecanum, for instance, might have a "stinger" to stop the bridge from tilting too far in the other direction. Depending on the angle of the bridge I could definitely see a low-traction drive like a mecanum having the force to slowly push a higher-traction robot.
You're correct, though, that lower traction certainly would make balancing harder. Does anyone have video of a high-traction and low-traction combo trying to balance?
As Madison stated before, the action of mecanum robots are actually in reality the high traction robots moving back while the mecanum drives towards the high traction robots. Theoretically, mecanums can't push high traction robots, especially upward (The only exception to this rule I know of is 357 with their Jester Drive:p ).
I wouldn't pick mecanums unless you have two other high traction robots. I've seen instances where the mecanums can't even go up on the bridge.
Zoughtbaj
19-03-2012, 22:01
As Madison stated before, the action of mecanum robots are actually in reality the high traction robots moving back while the mecanum drives towards the high traction robots. Theoretically, mecanums can't push high traction robots, especially upward (The only exception to this rule I know of is 357 with their Jester Drive:p ).
I wouldn't pick mecanums unless you have two other high traction robots. I've seen instances where the mecanums can't even go up on the bridge.
Likewise. At the Oregon Regional, just about every Mecanum I saw not only could not easily balance on the bridge, but had trouble even getting over the bridge. Interestingly, it would seem that CG would have a lot to do with that, but after what I saw, all the tipping and violence in the balancing process would simply cause the Mecanum wheels to slip. Traction wheels are definitely nescessary for a tripple balance, as well as small robots in your team. We are actually working on finding out how CG will effect the balancing process to see if we can integrate that into our scouting.
On a side note, one of our Alumni has deemed all of the bridges as "Catapults" and CP as "Catapult Points" :D
I wouldn't pick mecanums unless you have two other high traction robots. I've seen instances where the mecanums can't even go up on the bridge.
UNLESS your mecanum-drive robot has (1) "super-creep" (low geared, high torque - I think that's what they call it, I'm not a mechanical type) mode where it just crawls right up there, alone OR pushing another bot, and (2) "e-brake" gyro-based software which enables it to hold its position on the bridge using micro-adjustments (that's in lay terms and I might not be getting it right, but it's the general idea).
Our drivers can balance (and then turn 90 degrees to take up less bridge space), or double-balance (with our chassis-bot, 'cause that's all we have for a 2nd, but it weighs about 1/2 what our practice bot weighs, so that's another challenge - the chassis-bot has to hang off the end for the weight distribution to work out), pretty quickly. Haven't tried a triple only because we don't have 3 robots, but we can't wait to try it on that practice field in a couple of days.
Oh, man, I wish I had some video for y'all. Can't wait for this weekend.
UNLESS your mecanum-drive robot has (1) "super-creep" (low geared, high torque - I think that's what they call it, I'm not a mechanical type) mode where it just crawls right up there, alone OR pushing another bot, and (2) "e-brake" gyro-based software which enables it to hold its position on the bridge using micro-adjustments (that's in lay terms and I might not be getting it right, but it's the general idea).
I dont believe torque is the problem with mecanum wheels. The problem is that mecanum wheels just arnt designed to go up a ramp. I believe that when going up, the rollers on mecanum wheels (those that are the whole reason the function to strafe) just act like casters and you slide down the bridge. This is what we saw in very early testing anyway. In a way, this can be looked at as having "very low traction" on the bridge.
Anyone else see the same thing?
Well, all I know is that our (mecanum) wheels have absolutely no trouble going up the bridge (which is built as best as we could to spec, with the proper surface covering). Or stopping on the bridge while it is fully tilted. I guess I will leave it to the techies (I'm just the rulesmeister) to explain why (except I don't think any of them are on here).
And of course I'll eat my words if it doesn't work that way on the competition bridge. I love words, they're so tasty, I eat them all the time. (now what smiley would you put here? wink? embarrassed? ???)
pfreivald
21-03-2012, 07:05
Well, all I know is that our (mecanum) wheels have absolutely no trouble going up the bridge (which is built as best as we could to spec, with the proper surface covering). Or stopping on the bridge while it is fully tilted. I guess I will leave it to the techies (I'm just the rulesmeister) to explain why (except I don't think any of them are on here).
And of course I'll eat my words if it doesn't work that way on the competition bridge. I love words, they're so tasty, I eat them all the time. (now what smiley would you put here? wink? embarrassed? ???)
We can drive up the bridge and balance with just our mecanum wheels, too -- though balancing is even easier and more consistent with the traction wheels down. Where the traction wheels shine over the mecanum wheels is not moving nearly as much when bumped by a clumsy or over-exhuberant balancing partner.
Likewise. At the Oregon Regional, just about every Mecanum I saw not only could not easily balance on the bridge, but had trouble even getting over the bridge. Interestingly, it would seem that CG would have a lot to do with that, but after what I saw, all the tipping and violence in the balancing process would simply cause the Mecanum wheels to slip. Traction wheels are definitely nescessary for a tripple balance.
We have mecanums and were very good at balancing in the Boston regional -- the robot never slid, nor did it take us more than 10 seconds to double balance (http://www.youtube.com/watch?v=6wPRk2PcL6Y#t=1m25s). We also did a triple balance with 246 and 3958 on the practice field without traction problems.
EDIT:
I think part of the issue is that some teams have their mecanums geared way, way too high for easy bridge-climbing or balancing... Though from what I've seen this isn't just a mecanum problem.
We're using 1:16 worm drive and gearing was a non-issue.
pfreivald
25-03-2012, 12:54
I think part of the issue is that some teams have their mecanums geared way, way too high for easy bridge-climbing or balancing... Though from what I've seen this isn't just a mecanum problem.
I think part of the issue is that some teams have their mecanums geared way, way too high for easy bridge-climbing or balancing... Though from what I've seen this isn't just a mecanum problem.I have to agree. I've had many a team tell me simply, "we can't climb the bridge; see, we have mecanums". They don't seem to realize that this is largely meaningless without specifying gearing, but I'd believe some of their ignorance may be spreading to some other teams.
I have to agree. I've had many a team tell me simply, "we can't climb the bridge; see, we have mecanums". They don't seem to realize that this is largely meaningless without specifying gearing, but I'd believe some of their ignorance may be spreading to some other teams.
Again, mecanums are not unable to climb the bridges as demonstrated here (http://www.youtube.com/watch?v=tHQuOS7yu6U) and here (http://www.youtube.com/watch?v=U8VbrtNoKj0) (with lower weight and gearing). I'm not sure why people think that mecanums can't do this.
PAR_WIG1350
25-03-2012, 22:33
Again, mecanums are not unable to climb the bridges as demonstrated here (http://www.youtube.com/watch?v=tHQuOS7yu6U) and here (http://www.youtube.com/watch?v=U8VbrtNoKj0) (with lower weight and gearing). I'm not sure why people think that mecanums can't do this.
Because they weren't here for the 45 degrees carpet in 2010?
stingray27
25-03-2012, 22:41
Just throwing this out there that 3572 did an excellent job playing defense and stopping 2054 from balancing in the semifinals of Niles FiM tournament. Great job guys! Thanks to 2834 as well for your shooting. Might want to get the topic back on to stopping triple balancing though.
Well, we did actually have a LITTLE more trouble on the competition bridge, but it wasn't due to the mecanums. It was because our CG was too high. Midway through the competition we adjusted our weight distribution, and after that, we not only climbed the bridge, but balanced it successfully (alone and with a partner) several times.
The only sad thing was that we had a great strategy for achieving a triple balance with another very narrow bot (we tested it on the practice field, the two of us could actually climb the bridge side by side!) and any third bot, but neither of us were captains, and we got picked by the 6th alliance, and then the 7th picked them, splitting us up. So we never got to do it - and there was no triple balance at the Hawaii regional :( .
But overall it was a fantastic competition (the field system problems aside, that's another issue and we know they're working on it), our first elimination victory (we went down 2-1, but at least we won one! Last time we made it to quarters we lost 2-0), and it was great to see our bot dunking balls consistently in hybrid, picking them up, scoring, and balancing. Really rewarding to see all that hard work pay off.
So for us, next year starts tomorrow.
Hawiian Cadder
26-03-2012, 04:27
In the elimination round at Denver we successfully defended against a triple balance team, in the second match we were unsuccessful because they prevented us from crossing the field until the end of the match. I think that an alliance geared towards a triple balance should take a hard look at playing anti defense until 2 robots are on the bridge by preventing defenders from crossing the field or interfereing. Once we figured out that they would block the cooperation bridge and switched to our alliance bridge for crossing, they were unable to complete the triple balance.
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