In past years defensive robots haven’t been greatly successful. In a recent tournament I attended to watch though, I found that it could be different this year. In the semifinals, the four alliance had a robot slightly above average and two robots that were not very strong. They played against the number one alliance who had two great robots. The four alliance noticed that they would not be able to beat the one alliance in a pure offensive match, so they had their teammates block the number one alliance from the zones. Whenever they would try to score mobile goals, they would get pushed away. Meanwhile, the just above average robot worked on scoring as many points possible. The number four alliance ended up easily taking the series, even though neither of their robots were nearly as good. I am wondering what everyone thinks about defensive robots this year and if you think that they would potentially be a great pick for your third team.
I think early season this can be a solid strategy. I am not sure how good it will be long term as team figure out how to defeat the defensive strategy. One way that comes to mind it to have a large stack of cones on a mobile goal and try to push past the defensive team. If the stack is tall enough, the cones will fall and the defensive team will have a DQ. In the elimination rounds, the alliance gets the DQ and the offensive alliance gets the win.
Another way is to push the defensive robot all the way into the 10 point zone. That makes it eligible for a DQ as well.
You bring up a good point, but the rules say that if a robot makes a move attempting to get a DQ on the other robot, they will be DQed themselves.
Doesn’t it say in the rules that teams cannot block access to portions of the area
It just says that two robots can’t work in tandem to block a specific area.
But what they are really trying to do is get through. If you are blocking them from getting through, and they push you in a way that makes what you are doing illegal, the defensive robot is getting DQed 100% of the time.
The other consideration is that a robot may not touch a robot which is touching their own starting bar. A 36-inch-wide robot cannot block two opposing robots from getting to this starting bar and touching it. After they are touching the starting bar, it’s game over; they have free reign, and any contact with them will result in a DQ.
<G13> Intentional strategies causing an opponent to violate a rule are not permitted, and will not
result in an infraction on the opposing alliance.
This rule seems to imply that if a robot seems to “push you in a way that makes what you are doing illegal,” that would fall under “causing an opponent to violate a rule,” and the robot that was pushed would not be penalized. I would go so far as to say that if a defending robot was pushed into the starting bar (and held there), that would constitute pinning and a five second count would be initiated.
And just to clarify your second point, any contact with a robot touching its own starting bar will not result in a disqualification unless the contact is deemed match affecting. Though, as a defensive robot proponent myself, I’d be happy to give an opposing robot free reign over their own five point zone.
I think that strategies involving a mix of both offense and defense will be prominent throughout the season, given that defense can be as easy as stacking cones in front of an opponent’s mobile goal, forcing them to drive around or go for a different objective.
Your interpretation is not correct.
This situation has been answered.
https://vexforum.com/t/answered-blocking-opponents-from-entering-zones/41463/1
Basically, if the defensive robot is trying to stop the offensive robot from scoring into its own zone, and got pushed to the starting bar, the defensive robot will or might be DQ.
If the offensive robot, with no intention to score, but pushed the defensive robot to the starting bar, then the offensive robot will be at fault.
Trust me… when come to high stake matches, you dont even want to be in a situation that requires the referee to decide if it is match affecting or not.
Now, I am not against defensive robot, in fact, one of my teams had a wallbot during Singvex, but I still think there is no point having a pure defensive robot this season.
For this season, I just can’t see how a purely defensive robot can guarantee a win (during Worlds eliminations rounds).
Not sure if I have understood you - are you referring to stacking cones on the mobile goals in front of an opponent’s mobile goal?
If yes - then it might cause a mild inconvenience for the opposing alliance, but it won’t be a deal-breaker.
If you are referring to just putting the cones on top of another cone in front of the opponent’s mobile goal, then by definition, the cones are not stacked.
I wish you luck pushing a purpose built, well driven, very heavy blocking robot with grip wheels and lots of drive motors onto the starting bar. I think this is a strategy that could add interest to matches, as long as it is not too crippling for the other alliance.
The zones blocking strategy can most likely be combated by teamwork from the other alliance, for example one robot playing dedicated defense on the blocking robot’s partner while the other robot just scores cones. The outcome comes down to the relative strengths of the other three robots in the match and how well they can execute their plan.
Hi Meng. Can any robot guarantee a win during Worlds elimination rounds?
Think you misunderstood me quite completely.
A pure defensive robot is a type of what we call - specialised robot.
Specialised robot normally will not do well in qualifications.
And specialised robot normally apply “chokehold “ strategy.
Chokehold as in… when it is paired with an at least decent alliance, the strategy is so effective that the opponents can do nothing about it.
Eg.
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Green Egg in Round Up. Ok… it is no exactly a specialised robot, but it couldn’t hang and couldn’t even score at the highest goal… but one thing that it could do so well was that it threw mobile bases underneath the ladder so effectively that there was practically nothing you can do to stop them from doing it.
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2W during Gateway… the Mother of all wallbot. Watch their worlds finals… there was practically nothing the opponents can do to overcome their strategy.
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and even the most recent Starstruck… if 8000 series and 185 worked (mechanically) 100% of the time… there was not much the opponents can do.
So now… let’s do a bit of game analysis (or meta gaming) of having a pure defensive robot for ITZ.
Let’s assume that this robot main task is to stop the opponents from scoring into the zones (eg. 8059J).
Think by worlds elimination, all the robots should be able to at least grab a mobile goal back into the zones during auton… the defensive robot can at best stop one opponent from taking a mobile goal back… which means the opponents will have at least one mobile goal in the zones at the end of auton.
At driver control period - the defensive robot move into position right outside the opponents’ zones.
And now the dilemma - how do you want to orientates the wheels? Parallel with the starting bar so that it can move along the bar fast enough to block? Then the robot will be exposed or vulnerable to be pushed to the bar.
Perpendicular to the starting bar? So that it can make use of the pushing power? Then the robot will not be quick enough to move sideway to block.
How abt adding a pneumatic brake and at the same time having the wheels parallel to the bar? So that it can move sideway fast and also at the same time withstand the push? The problem is that this year there is a 36” limit rule… there is no way the robot can open wide enough to cover the entire frontage of the starting bar. This means the opponents can rush in from both sides of the zone at the same time. The defensive robot can only stop one at one time.
And of course, not forgetting by placing the defensive robot to guard, it is 1v2 out at the open field. The opponents can easily get their weaker robot to block the attacking robot and they still have one more robot going around to score.
And there are too many DQ-able moments when the defensive robot is trying to block the opponents… touching the starting bar is one… and accidental descoring when the offensive robot is trying to get past the defense is another.
But of course, please do your own analysis. All of us will arrive at different conclusions 
Just curious - have you built or driven a wallbot before?
At worlds, cones will be much more important than mobile goals. This means blocking the zone will only prevent a small proportion of points being scored, rather than most of the alliances points as it is now.
That’s not necessary. 36 inch wide robots can’t cover both sides of the bar, so if two robots try, one can get through, and then it’s all over (you can’t touch them after they touch their starting bar).
Why is cones more important at worlds?
Early in the season, the ~50 points from mobile goals is a very large proportion of an alliance’s score. In our most recent tournament the highest scores were ~100, so about 50% of our score was mobile goals. We stacked about 25 cones a match. This means that playing serious defense against the zones will cut scores by about 50% at this time in the year, which makes it worth giving up a robot.
At worlds, nearly every cone will be scored. This means that scores will be routinely >150, which means the ~50 points from mobile goals is now <1/3 of the alliance’s score. This means sacrificing one robot for defense will only cut your opponent’s score by, at best 50 points, but your partner will only get about 75 points by themselves. You still lose.
And this assumes that you can block all 50 of those points, which as you mentioned with autonomous is not going to happen. When teams played defense against us, they cost our alliance <20 points, and that was often with both our opponents both blocking zones and knocking us around to prevent cone pickup.
Finally, when the GDC adds a bunch of cones and mobile goals, there won’t be any room in the 10 or 20 zones to put mobile goals.
I believe that he is saying that there will be more cones stacked at worlds simply because the bots will have the ability. They will eventually run out of mobile bases to stack on so they go higher.
What I noticed this weekend, while a robot cannot block the whole scoring area, the defense robot can position themselves in such a way the the stationary goal denies easy maneuvering.
If the offensive robot wants to get around the defensive bot they have to go around their stationary goal costing them them valuable time and giving the defensive robot more time to block.
Its a cheesey strategy and was causing serious animosity between teams.
That doesn’t make the cones more important than mobile goals.
4 mobile goals give you 50 points… which is equivalent to stacking 25 cones.
Yes… you can’t ignore the cones, in fact you need to be very good with the cones. But the mobile goals are your baseline (= You can’t win without the mobile goals).
Another way to look at it is - try not to score your mobile goals into the zones, but just stack your cones… I am not so optimistic about the chances of winning.
The key to defense is to pick and choose what defensive plays you use. You don’t want to go pure defense, but short but deadly plays like knocking over mobile goals or shoving a cone in front of your opponent is good strategy. Use a mix of the most effective offensive and defensive strategies.
Keep in mind that knocking over mobile goals with Stacked cones is illegal, even unintentionally. Cone hoarding (not exactly what you’re referencing) is also illegal
Which is why you always want to have a good offensive bot in case the refs call you on something. Personally, I think the best thing for this year is an internal stacker that plays offense with the front of the bot and plays defense with the back of the bot.