[Chilli]

I believe Defensive Robots will shut down nearly every top team I've seen, including Oly Cow, Masquerade, and i^2 robotics. Although you guys might have seen robots playing defense on you, the introduction of the super heavy exclusively defense robot will be a whole different story.

So, at West superregionals at least, and perhaps in other places, there will be at least one defensive robot. I feel that, if you score balls, and especially if you are a high scoring team, it's likely that you will be shut down by a team like the one that shut us down, the Enterprisers.

Just for some reference, our robot scored in a match 485 points by ourselves, as well as 535 with a partner. In our field test, allied with another robot, we scored 737 points. This was in addition to us not dragging the 2 goals back to the ramp as well as us deciding to practice on the opposing team's center goal instead of going back up the ramp. We ended up as 2nd alliance captain, winning our first series 580-~100 and 400-~200. However, as said earlier, a defensive robot, Enterprisers, shut us down effectively.

Specs: 40 pound robot, with 8 andymark stealth wheels, 4-6 motors on their drive train(don't remember exactly). However, it's likely that they'll add up to 8 motors on their drive train for supers/worlds. They do have a cup where they can place one large ball, but we never saw them succeed in scoring. Generally, they score 0 points in the match, other than coming off/on the ramp.

This is their strategy. Often, during autonomous, they'll drive into our goal, or alternately, pin us. This prevents us from scoring in the rolling goal, and puts them in perfect position for their teleop strategy.

During teleop, they use several defensive strategies.

1: They have a button that pins for 4.8 seconds and then backs out. This allows them to avoid penalties for pinning. After backing out for a bit, they ram us again, making it very difficult to maneuver. It is extremely difficult to push against them, as they are 40 pounds, have immense traction with 8 wheels, and have lots of power with 4-6 motors. This does not invalidate any rules and was not called for any penalties.

2: They block us from getting to the rolling goals. If they sit in the space between the 60, the ramp, and the center structure, they have the perfect position to block us. It isn't considered "blocking access" to the center goals as if they couldn't move, you could move around them. However, in practice, this is very difficult unless they mess up. If you shift up, they shift up, and if you shift down, they shift down. With the walls and the center structure in the way, this would be nearly impossible to get back if you executed completely perfectly.

3: If you manage to grab onto the goal, they start pushing you around. They did only follow the 90 cm robot around, but 90 cm gives a lot more points than 60 cm. Perhaps our robot, with only 2 stealth wheels and weighing only 22 pounds was especially susceptible to us, but they pushed us around like they were playing battlebots. This allows them to pin us against the wall, where they can resume strat number 1. Alternately, they've also pushed us onto the kickstand where we were stuck. Even if they can't do any of those, it makes it very difficult to pick up balls. As stated before, it's very hard to resist being pushed against this team. 8 stealth wheels gives great traction, 4-6 motors gives lots of power, and 40 pounds makes it hard for them to be pushed.

4: If they mess up and you manage to grab 5 large balls and go for a dump, they back up and ram you as you're dumping balls. Our lift was not stable enough at 90 cm to dump consistently, but I've seen their strategy also work against continuous robots.

During endgame: During endgame, they have one primary goal. Prevent teams from scoring in the 120 cm goal. To do this, they tend to skirt in the area around the center goal, nudging the other team here and there. If they can, they try to get in between you and the center goal. Otherwise, if you manage to get in position, they back up and ram you. For us, this would often push us out of position, and made it difficult to line up properly. In addition, due to the force their 40 pound robot can apply, our lift would wobble a lot.

I will note that they tipped over a robot going for 120 cm in the finals. Although they got a major penalty for this, 50 points < 162 points. Also, that other robot couldn't do anything for the rest of the match. It ended up being a net positive for them.


ABOUT PENALTIES:
In the matches that we saw, they did not get penalties for any of their actions(except for tipping over a team). They have learned their rules extremely well, and through a combination of good driving and programming(ie: their 4.8 second pin preset)

Any team that hopes to go far should think long and hard about how they would deal with a robot like this. Here are some questions you should try and answer. If you can't think of a solution, defensive robots may be a problem.

1. How will you break past the pinning cycle? As you can see in the rules, this is not prohibited at all. G10: A Robot cannot Pin or Trap another Robot for more than five seconds. As you will be able to move in the 1-2 seconds they back up, this strategy was considered legal.

2. How will you get to the 90 cm goal? You likely will not be able to push them out of the way, and it's very difficult to get near it if they play well. One thing we tried was grabbing the 60 cm and letting our lower scoring partner grab the 90. Although the enterprisers focused on the 90 cm robot, leaving us free to fill the 60, we were not able to get nearly as many points. Still, we lost, something like 340-354(due to a major penalty they forced us into committing).

3. Can you dump in the 90 while getting rammed? I'm guessing that many teams will have trouble doing this. Most lifts are not extremely stable, and the enterprisers crashing into you causes a lot of force.

4. If you can dump in the 90, can you dump in the 120 while getting rammed?

How to build a robot like Enterprisers: ~12 hours required.

I made this list so that teams can see how to build a defensive robot.

Ingredients list:
8 Neverest Motors
8 Andymark Stealth Wheels
Stuff that makes you weigh a lot.



As the Enterprisers never did use their lever for scoring, I'll forgo that part.

1. Create a super heavy chassis. I'm not quite sure how heavy you should be, but the Enterprisers were 40 pounds. Feel free to add weights to your robot to make yourselves heavier.

2. Attach your 8 motors and 8 wheels. I'm not sure what would be the best configuration of motors/gears/chains, but feel free to choose your own option.

3. ???

4. Eliminate robots that can score.

5. Make sure to read the rulebook carefully. Make sure you pin for 4-4.9 seconds, never 5.

Congratulations, you now have a very capable defensive robot. Follow the strats outlined above, and you should be ready to shut down almost every high scoring team!

To the other high scoring teams. Hopefully you guys can deal with them better than we could. Some solutions are: Adding ramps to the sides of your robot so that they're flipped upward when they ram into you, driving up the ramp so that they can't follow you.

Credit to Enterprisers for finding this strategy. I suspect it'll work against many teams.