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Defensive Robots/Strategies?
Considering the shuttling and the importance of cycle times in this year's game, how effective would defensive strategies/robots be?
Would it be a better idea to defend against gear or ball scoring robots? What design elements/components would increase a robot's defensive capability? Would a hybrid gear + defensive robot be viable? What would defense this game look like? |
Re: Defensive Robots/Strategies?
I think that to be an effective defense bot all that you really have to do is go to the opposing alliance's launch pad and clog up some of the narrower passages between the drive station and the airship. Then there is also of course the ability to severely lengthen your opponent's cycle time just by being in the way and forcing them to adjust their path in the neutral zone. Make sure that you check up on the rules before pursuing any aggressive defensive strategies.
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They will either A)need to go around the air ship to not deal with you or B)try to get by you If A: Go diagonally towards their desired path they will either: 1) Redirect and play chicken, 2) Run into you and now you have a pushing match heading towards your safe zone so they are risking a penalty 3) You pin them for a legal pin If B: Don't let them by turning it into a pushing match or pinning them legally Either they get by you or you spend the entire match shutting them down if it is the latter congratulations, you did your job and will be on someones pick list for effective defense if not. Once they get into the area to score the gear that is not a safe zone, be as disruptive as possible and you will either slow them down or make them drop the gear. Either they score the gear or they don't. If the latter once again congratulations, you did your job and will be on someones pick list for defense if not repeat the steps listed above. If someone is making you waste this much time the whole match than there is no way you are cycling fast enough to engage the rotors by themselves. |
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The mandatory feature required of all teams attempting to play shutdown defense near the opponent's airship will be a way to solve the visibility challenges presented by the airships.
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Say Robots A, B, and C are on an alliance. Robots A and B can score a total of five gears. Robot C can place up to three gears and play defense. If A and B place their five gears (plus the free gear), the alliance engages two rotors (80 points). If A, B, and C place their maximum eight gears, the alliance engages three rotors (120 points). However, if A and B place their five gears and C places one gear then plays defense, the alliance still engages three rotors (still 120 points) plus they gain whatever havoc C wreaks on their opponents. |
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1) Vertical Defense- Use your robot to block potential fuel shots by choosing to build using the volume option with a focus on height (30 in. by 32 in. by 36 in. tall (~76 cm by 81 cm by 91 cm tall)). This option is difficult to pursue for 2 reasons:
2) Horizontal Defense- Use your robot to effectively pin opponents by selecting the volume option with a focus on width (36 in. by 40 in. by 24 in. tall (~91 cm by 101 cm by 60 cm tall)).
G11.There’s a 5-count on pins. ROBOTS may not pin an opponent’s ROBOT for more than five (5)
G08. Don’t tear others down to lift yourself up. Strategies aimed at the destruction or inhibition of G09. Stay out of other ROBOTS. Initiating deliberate or damaging contact with an opponent ROBOTIn terms of contact, both vertical and horizontal builds should be equally effective, but the width of the horizontal should be more effective for pinning. In regards to height, the distance from the ground to the top of the high efficiency is roughly 27 in. The maximum height for a vertical bot is 36 in. and for a horizontal bot is 24 in. The horizontal bot should semi-effectively block shots into the low efficiency goal, so this is something to consider when picking a strategy. In summary, your most viable option is probably to pursue interfering with ball-shooting robots. They are easier to throw off, as many teams seem to be implementing safeguards against gears falling off. |
Re: Defensive Robots/Strategies?
We reviewed some core defensive strategies in our video update of weeks 1 & 2, so we recommend your team checks this out to see how other teams are implementing some of these strategies!
https://youtu.be/PJhMr0CW83s |
Re: Defensive Robots/Strategies?
The field this year has some semblance to Ultimate Ascent's field, with large field objects creating chokepoints. The chokepoints this year are the two corridors where robots can exit their key.
Optimally played defense will make it extremely difficult for boiler-scoring robots to leave the key after their cycle, as IMO, playing defense on intaking robots is more important than defense on scoring robots, as accuracy matters less than volume of fuel fired. A blue robot shifting between these two positions can significantly disrupt an opponent's cycle time, and even has the potential to entirely lock them out of acquiring new gears or fuel to cycle. http://imgur.com/a/NA1uK |
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I hope we see a shooter than can put up 40 pts in auton. They'll seed high and should be able to pick a good auton gearbot and another gearbot. That's enough points coming out of auton to win with a pure defense teleop strategy. In a gearbot vs gearbot race, the first alliance to 4 rotors will have to decide to go full defense or shoot. If they get to 4 rotors with a 4 gear lead, it probably makes sense to go full defense. Or put up a point of fuel just to cover the case of a rotor tie before switching to full defense. An auton fuel dump into the low boiler by a gearbot will be valuable for the same reason. If an alliance feels they can win in the climb, it may pay to be very defensive as well because climbs can dominate low point games. Strong defense and good clock management will be very hard to play against though it requires more coordination than alliances can normally execute. It will be fun to watch these matches and see where the meta goes! Best advice this year (as it is most years) is don't skimp on your drivetrain. Speed and reliability are critical to both offense and defense. |
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The more experience your drivers have, the better they will be at all aspects of the game, especially defense. There's something to be said for keeping your design simple and finishing early so that you're drivers (and programmers) get more time with the robot. And the thing about practicing defense is you don't even need a full robot to begin practicing; all you need is a functioning drive train. Unless you can pull off a more complex drivetrain such as swerve or octocanum, I'd stick with tank drive (as in 6 traction wheels, not treads). This is a very contentious topic, but most people, myself included, would highly advise against using a mecanum drive or an H drive, as the (slightly) increased mobility is outweighed by the fact that they will get pushed around easily by other robots. And if you have well-trained drivers, you should be totally fine with the mobility of a tank drive. As for the transmission, I like shifting gearboxes. You can have a very low speed which is great for pushing other robots, and you can have a high speed which is good for traversing the field quickly. Quote:
If you're talking about strategy, it could work. If you're confident your alliance can get 3 rotors activated but highly doubtful your alliance could get up to 4, one good use of your time instead of cycling useless gears would be to play defense. A hybrid fuel + defensive strategy for your robot might be even better though. To pickup a gear requires that you fetch it from a specific location on the field, whereas fuel can be found everywhere. This means that you can both intake fuel and play defense at the same time. |
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I am very excited to see how D will play out this year. Can't wait. ;)
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Remember that this field is mirrored rather than rotationally-symmetric. This means that the pinch points your defensive bot exploits also force your partners to go even further to place their gears. Sure, we could start getting into "but we'd go here, and you'd go there, but what if this and that.....". Yet there still remains a fundamental issue with playing zone defense that has no easy answer.
Just be sure your bot can deal with 120-150lbs of another robot crashing into you because you decided to get in their way while their robot was in 'ludicrous mode' ;). |
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"There is no FIRST® Robotics Competition specific definition of pin, so a general definition applies; “to prevent or stop something from moving.” As a result, contact is not required for pinning to occur. For example, a ROBOT parked right behind an opponent that is between dividers could be considered pinning because the dividers and the parked ROBOT prevent the opponent from moving." So would contacting a robot for a period of longer that a 5 count be allowed assuming both robots were moving? Such as in the case of continued bumping or pushing? |
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But imagine this scenario: Robot A is moving towards some point on the field to score points. Robot B wants to play defense on them, and so Robot B drives headlong into Robot A to prevent them from scoring. Both robots are in an open area, pushing head to head and neither are moving for over 5 seconds. This is typically not considered a pin. While neither robot is moving, Robot A could, at any time, throw it in reverse and try an alternate route. Robot B is preventing Robot A from getting to their destination via the most direct path. They are not preventing them from moving at all. Now imagine this: Robot A has just scored, has one end against a wall or some other obstacle, and wants to drive back tot he other end of the field to reload whatever scoring piece. Robot B wants to play defense. Robot B does this by driving headlong into Robot A, driving it into the wall. Neither robot is moving for over 5 seconds. This would typically be considered a pin. Robot B is preventing Robot A from moving whatsoever and would be in violation of G11. While that doesn't directly answer your question, you should be able to draw the correct conclusion form that. |
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Our team saw the defensive strategy in this game as being similar to Aerial Assist. Both had fairly open fields, and pinning for longer than usual was allowed. What worked very well for us was going across the field at full speed on a 6-CIM drive and hitting opposing robots, then shoving them. It is unclear as to whether this is allowed this year, but a hit to a corner would definitely throw off a team's aim. A hit while placing a gear on the peg could also interfere, as could blocking chokepoints. What I'm trying to say is that we think that harassing opposing robots is better than constantly trying to defend. One idea we also had, which is of questionable legality, is to ram the opposing alliance's airship while a pilot is lifting a gear. If this is allowed, and depending on the construction of the airships, this could cause a pilot to drop a gear.
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I think that this really isn't the best possible defensive strategy. Your better bet would be to go after the robot while its trying to place the gear. Even if their gear just drops into a slot that the drivers pick up from, which is by far the simplest option that there is, then you can still hamper the teams ability to proper place the gear on the peg. |
Re: Defensive Robots/Strategies?
This kind of thread is among my favorite. So much good information, point and counter-point, and I most often defer to the teams with the most experience in planning and executing this aspect of the game.
This year however has two very striking differences, and only one mentioned here so far. The fact that this years field is mirrored, meaning that instead of counter current flow, most team's modeled and practiced cycle times will likely mostly occupy the same space, leading to offense basically having a built in defense - or the stronger bully wins. This also means that defensive skirmishes have to be well designed and executed or you are interfering with the cycle time of both you and your opposing alliance. Couple that with more than one skirmish and you could shut down the whole field, especially in elims with 4 total gear runners. The second difference is the possibility for hundreds of game pieces littering the field. Not all robot-robot interaction is going to be the classical, and by now predictable, bumper-to-bumper, my drive train is better than your drive train pushing around...there's going to be balls (and maybe gears) stuck between bots in what may be a completely untested fashion. Remember the old trick, now outlawed, of putting solid noodles on bottom and hollow on top in order to jack up an opponents bot to get the upper hand. I predict many robots will be getting jacked up on fuel, and I'm not talking about Red Bull. This years game is sure to be a crowd pleaser, and I further predict as the competition weeks progress, when offensive strategies progress so too will defensive strategies and we may not see the steep curve in high scores that we did last, especially considering the diminishing returns of gear running. |
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What about a team who builds a very small drivetrain then just defends shots.
Ex. A team chooses the 36x40x24 volume and builds a 29x18x24 chassis. They can now extend approx 15 inch from their frame. They could extend a 15 inch shield or sorts to hover over top the opponent shooter. Like team 1405's robot in stronghold. |
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One thing that might happen is robots is fuel getting stuck in gear mechanisms, specifically passive ones, incapacitating them for that match. In theory, intentionally doing so is almost definitely illegal via G08.
"Don’t tear others down to lift yourself up. Strategies aimed at the destruction or inhibition of ROBOTS via attachment, damage, tipping, entanglements, or deliberately putting a GEAR on an opponent’s ROBOT are not allowed." Violation: FOUL and YELLOW CARD. If harm or incapacitation occurs as a result of the strategy, RED CARD. There are some hypothetical scenarios where this could be a problem however. If robot A pushes robot B into a hopper, causing one of the 50 balls to get stuck in, and incapacitate one of the mechanisms on robot B, what happens? How do you judge intent of an otherwise acceptable defensive action? The strategies "aimed at" wording makes it seem like intent would need to be present to draw a foul, but wouldn't it therefore be a result of strategy and always draw a red card? Obviously it is the head refs discretion, but is there any direction you think these rulings would normally go? |
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