Offensive/Defensive

[krisloz]

In FTC, I heard some people ask me if our robot was offensive or defensive, and I thought, shouldn't all robots aim to be offensive (score points)? This was in the regionals so the stakes were up.

What would be Pros of having a defensive robot and how far would you get in building one? Can you get into worlds with a defensive robot? Maybe if people are crunched up in time and resources, a defensive robot is the way to go, but how effective is it too? A lot of questions, sorry, but this is something I may be interested in doing later on.

I hope I'm posting in the right section, offensive/defensive robots never seemed like a strategy until that question came up.

[Gray Adams]

A strong defensive bot could easily be a 3rd pick at championship. In this years game, a good defensive bot should be able to pick up balls super easily, launch them across the field with little regard for aim, win any pushing match as well as out race any robot, and cross the bump with ease. A strong offensive robot doesn't necessarily need to cross the bump that well, doesn't need to be able to push exceptionally well, but it should be quick, good at picking up balls, and very good at making baskets.

So there are different things to focus on assuming you don't have the resources to build the perfect robot that does everything. A good defense robot could hold fender shooters to 0 points and prevent a double balance, easily enough to win matches.

I wouldn't write off purpose built defense robots with trained drivers (although I don't really give too much thought to the robots that have some kind of large sheet of material to obstruct vision and shots).

[Paul T.]

defensive strategies can be good if executed correctly, if the opposing alliance has no scoring elements how are they going to score? but the downside to this is having good alliance partners. if your alliance partner can't score more than the robots your trying to play defense on you cant win. FIRST has done a good job giving you enough scoring opportunities and places to make defense really hard but how will the other alliance score if you have all the crates and balls? i would make a wall that pushes everything to my side of the field and then right a bin throw a ball in it and raise it really high. that way i starve my opponents of scoring chances and assure myself a ton of points

[krisloz]

It's just really hard for me to visualize a defensive robot helping an alliance out.

So it doesn't outscore the opponent, but prevents them from scoring altogether? Would it need to have a way to score points by itself? It seems like such a vulnerable robot if it's relying on those tactics.

[BrendanB]

Defensive robots have their place on most alliances. Team 179 Children of the Swamp played some extreme defense in 2007 and were finalists on Einstein. Most robots play defense like 179 and just push, push, push but some use other strategies. A few this year made their robot as big as they could and tried to block robots shooting from the key. Previous years included robots that kept game pieces away.

We design our robots to have a minor in defense meaning that if our offense fails we can still play effective defense. 6wd traction wheels with AM supershifters give us a good edge when competition comes around and we have no trouble pushing people around and pair well with our offensive strategies because we can normally out maneuver a defender.

You are right every robot should aim to be offensive but in an equal way every robot should have a last ditch play aka defense.

[Borobo]

this year, we built a primarily offensive fenderbot with custom gearboxes geared for 16 and 6 feet per second nominally for fast ball pickup and resisting defensive play respectively. in the Denver regional, we ended up initially playing pure offense, but once we got to the semifinals and finals it turned out to be more effective to play pure defense against triple balances and high scoring teams (399 and 2996) while letting our less defensively useful but higher scoring alliance partners (1245 and 1158) focus on scoring baskets. In this case our defensive play, which was for the most part very effective consisted entirely of ramming in low gear, which we almost never used for actually scoring or preventing defense

[Walter Deitzler]

In 2011, 3397's D-Bot went to Championships after being the #2 choice of the #1 alliance. During the finals at the World Champs, I recall 973 playing defense to prevent to other alliance from scoring. Can it help you and get you far. My experience says yes.

[krisloz]

Wow, that was awesome, but FTC has a really small game space, or is it just that this year there was too many game elements? But I can see how being defensive is helpful, though I'm not too sure it would be in FTC with the limited space and everything.

[Jaxom]

Originally Posted by krisloz

It's just really hard for me to visualize a defensive robot helping an alliance out.

So it doesn't outscore the opponent, but prevents them from scoring altogether? Would it need to have a way to score points by itself? It seems like such a vulnerable robot if it's relying on those tactics.

Defensive robots can absolutely be an incredibly useful part of an alliance. Some years' rules lend themselves more to defense than others, but this year's sure do. With a very limited number of balls available and having to rely on your opponents' scoring to get balls back (at least in part), you only have so many balls that can be scored. Having 3 prolific scorers doesn't work; supply can't keep up with the demand.

In St. Louis, 1986 & 1985 could score well enough to keep up with most alliances. We chose 4356 as the 24th pick (a steal, imo) because they had a solid bot, were fast, and could tip the ramp & balance. True, they weren't designed as a defensive bot, but the fact that they didn't have enough build season time to finish their shooter didn't keep them from being useful. They did a great job banging up the other alliance -- it's tough to be a fender shooter when someone rams you as you're lining up a shot. And of course they balanced well & contributed to lots of double balances. We picked them for their bot's skills, and for their drive smarts, and they delivered. We wouldn't have won without them.

This year's penalties around the key & lane did limit defense, but not enough to stop it. 931 in St. Louis designed themselves as a defensive & balancing bot; they did it very well. They showed very smart driving; I did see them get a couple of penalties but they also drew a few. And they very clearly disrupted scoring on many occasions during the tournament.

[krisloz]

I felt that this year's game made it hard for a defensive robot, in FTC. I saw what you do at FRC and it just looks like you have so much space to bump and push with a defensive robot.

In FTC: Bowled Over, I don't think a defensive robot would be a good idea. There were just too many game elements on the ground to work with, plus they were all just too messy. Racquetballs get stuck really fast and you don't just push them, unless you build your robot specifically like that.

[Anupam Goli]

Originally Posted by krisloz

I felt that this year's game made it hard for a defensive robot, in FTC. I saw what you do at FRC and it just looks like you have so much space to bump and push with a defensive robot.

In FTC: Bowled Over, I don't think a defensive robot would be a good idea. There were just too many game elements on the ground to work with, plus they were all just too messy. Racquetballs get stuck really fast and you don't just push them, unless you build your robot specifically like that.

I wouldn't be too sure of that, I was FTA at the Georgia State FTC Championships, and I saw some interesting strategies. The first seeded alliance chose two bots that could stack crates HIGH. They had to get ladders out to measure them.
Alliances 1, 2, and 4 went for offensive powers. Alliance 3's captain (1002) went for a pure defensive alliance. Alliance 3 consisted of 1002, whose main offense consisted of bowling ball autonomous and blocking the other bowling ball from scoring in autonomus, and magnetballs; 4911 for their defense, and 5096 to put a crate in their robot and play defense. This alliance made it to the finals and forced a 3rd match in the finals, and all the alliance did was play defense and score magnet balls. They were able to successfully stop the other alliances from stacking high and that's how the advanced onto the finals, but it was only because of NXT issues that this alliance didn't win. Defense, when done correctly, is powerful.

[jfporter]

I hate to correct you but the 2 teams that could lift the crates high were on 2 different alliances. The 3rd match in the finals would not have happened if someone had not moved some cables on our robot. Don't know who did but they were moved so our bot was completly immobile for the first match. But in answer to your question, if you have a consistent offensive robot and keep opposing alliances defensive stratagies in mind, I would go offensive. Btw, We won the South Carolina championship tournament.
We are going to World as the holder of 2 individual states (Ga & SC) alliance and individual scoring records

[AlexH]

i drove a D bot last year for 1391 and we made it the the finals at philly.

the basic idea behind D is to disrupt the flow of the game and keep the opposing alliances bots from scoring. same thing applies to non robot sports like hockey, football, or soccer.


a good D bot has three things

1. high torque, high traction drivetrain, and a strong frame that can take serious abuse
2. the ability to disrupt the game
3. a driver who isn't afraid to hit and push other robots

[Jaxom]

Originally Posted by AlexH

a good D bot has three things

1. high torque, high traction drivetrain, and a strong frame that can take serious abuse
2. the ability to disrupt the game
3. a driver who isn't afraid to hit and push other robots

And in this game, you need 4) A driver & drive team observant enough and smart enough to avoid penalty areas. Or maybe that's 3.1? We've seen teams with only the first 3; it's not always pretty.

No one expects the Spanish Inquisition.

[Hawiian Cadder]

Originally Posted by Jaxom

And in this game, you need 4) A driver & drive team observant enough and smart enough to avoid penalty areas. Or maybe that's 3.1? We've seen teams with only the first 3; it's not always pretty.

No one expects the Spanish Inquisition.

When we played defense at Colorado we earned a lot of points by pushing other robots into our lane. Getting pushed into the middle of the field and the key shouldn't be an issue with the right drive train.