In Defense of Wallbots - Rebuttal to VortexCast's Treatment of Wallbots

Hi everybody,

Many of you may have watched VortexCast last night as they discussed a number of topics relevant to Tower Takeover. In my opinion, the stream as a whole was fantastic - for anyone who missed it, I highly recommend that you take the time to watch it once the archived version is released.

However, I and several others found the wallbot segment of the stream to be less comprehensive and more one-sided than VortexCast’s usual standard. As a member of the NorCal RI3D wallbot team, I admit that I am obviously biased towards liking wallbots. Still, I think it fair to say that there are valid counterarguments against much of the reasoning that last night’s VortexCast panel used to condemn wallbots.

In the interest of providing a more balanced treatment of this subject, we have compiled a document below that we hope serves as an informal rebuttal to the some of the anti-wallbot arguments during VortexCast wallbot segment. Of course, the panel also made a number of pro-wallbot remarks that we see no need to counter, and so those arguments have not been included below.

If you were interested by the wallbot discussion last evening, then I think you will find this document very interesting as well.

In no way do I claim that this document is a “slam dunk” that ends the conversation on wallbots or proves that wallbots are the best strategy. Instead, it provides evidence supporting the other side of the coin of what you may have heard so far.

I look forward to receiving and responding to your feedback.


I actually really appreciate the effort taken to create a professional discussion about what we talked about last night. Thinking back over it now, I dont think that the topic was discussed enough in full so I just want to share some of my thoughts on wallbots now. The biggest issue I have with the wallbot is that it can be 100% outplayed in auto. If you think about it, its a 2v1 in auto and i think its fair to assume that the team without the wallbot is going to win auto (because of the auton line). That being said, once driver control is started. I dont think it really matters if theres a wallbot blocking off a goal zone because at that point, the team without the wallbot can effectively prevent the other robot from scoring anything. Now for this all to work, the team without the wallbot has to have a strategy and a plan that will work during auto and cant get scared and stuck up on trying to move the wallbot if they are already ahead in points. As for vexu the same goes except that theres significantly more time to score in auto where the wallbot will be doing nothing until tele op starts.


The counter defense acting from the expanding x drive (screenbot) and the speedy pushbot are severely downplayed. With those acting as assists, if your partner can’t outscore what the other alliance pulled off in 15 seconds, there’s other problems.


I feel as if wallbots will be so much more effective this year than pretty much any other year in vex. Unlike most other events such as tp, the only way to score points is to put cubes in the two goal zones. Nothing else gets you points, unlike tp where there were flags, poles, and caps, and balls.
As a result, defense would be way easier to do making wallbots more viable than they’ve ever been


While a lot of the wall bots I’ve seen haven’t been able to score, they are feats of engineering and great partners for any tilter that can score a bunch, even without tower capabilities. I approve of wallbots, and while I’m not building a wallbot, I am planning on having a defense against the defense. My secret weapon, if you will. (Not expecting to see a bunch of wallbots in Kentucky though.)


As Qaiz mentioned, I really appreciate the kind words you stated toward our cast and I’m happy our hard work seemed to produce a solid cast in your opinion. With that said, I was somewhat surprised to see this post, as I believe it somewhat misquotes us and makes it seem as our conversation on wall bots was very one sided. Rather, we gave credit to wall bots and all agreed that the strategy was viable if done correctly during the cast. My goal for every cast is to get a lineup of people that people would love to hear from and be able to listen to their opinions on specific topics. In addition, I try to always get a group of guests that all took a different approach to their robots during the year to provide different type of conversation. For example, last year, we had at least one person on the cast that had a flywheel, puncher, and catapult robot at all times, which produced solid debates and conversation in general. Anyways, I love a good ol’ controversial bot design so I’m going to give my in depth opinion on wall bots.

To start off, I applaud your entire ri3d team in NorCal, as you guys produced an outstanding bot within a limited amount of time that was certainly outside of the box. In addition, due to your wall bot being the only one released currently, all arguments stated will be in regards to your specific wall bot, and not wall bots in general for this year.

During the segment, I stated that the alliance without the wall bot should be able to win auton easily and ride the point advantage throughout driver control. You stated in your doc that “if the wall bot’s partner cannot overcome a mere 6-10 point advantage in the entire 1:45 period, we would have lost the match anyways”. Now I also stated during another segment of the cast that each team should be building their robots in anticipation for worlds, and always have that in the front of their mind when strategizing. So let’s assume that this scenario is at worlds, with worlds caliber bots. For the sake of the argument, we will assume each teams autonomous runs. Let’s say the robot on the bottom of the field on each alliance (that starts closer to the smaller scoring zone) does the 25461Z autonomous run, where they score 8 cubes in the small zone in auton. Also, we will say that the robot on the top side of the field on the non-wall bot alliance does a 7 cube auton in the larger zone (which is completely doable at worlds). This brings the score after autonomous to 21-8 due to the 7 cube advantage + the 6 point autonomous bonus. In driver control, you stated that the large wall takes ~5 seconds to deploy. This is more than enough time for the bot that just scored the 8 stack in the smaller zone for the non-wall bot alliance to push or intake the group of 4 cubes that would be in the middle of their side of the field into the larger zone, as well as their partner to intake the 2 purple cubes they were just awarded for the autonomous bonus and take them to the large zone as well. This is another 6 cubes bringing the match score to 27-8. This now makes it so the wall bots partner has to score 19 cubes in their large zone just to TIE the match. A lot of bots won’t even have the ability to due 10 cubes making it impossible without tower play (we won’t account tower play into the argument, as it complicates the theoretical situation too much). In addition to this, the 1 bot that can actually score on the wall bots alliance will still be enduring heavy defense the whole match, making it very hard to score their 19 cube goal to just tie the match. Now, I know you stated that you also have two defense bots, that can help create space for their partner to score and keep the other alliance away from them basically making it a “1v0”. This is not correct for a multitude of reasons. Your 100 rpm 3.25" holonomic drive is very slow and cannot keep up with a bot with a normal amount of speed on their chassis. Even if they do, I doubt that a holonomic 4m drive will have ANY pushing power against a 200 rpm tank drive with either traction or mecanum wheels on their chassis. In addition, even if the wall bot DOES manage to abuse the two bots on the non-wall bot alliance, there will technically be 5 robots on the field, and 4 of those 5 will be trying to play defense on another bot. This makes for a VERY chaotic field and makes it highly unlikely that the wall bots partner can gain enough rhythm or momentum to score 19+ cubes in two stacks, giving the match win to the non-wall bot alliance.

Now this is my initial strategy against this NorCal specific bot that I believe would be able to crack their “seal-proof” strategy, but there are also a few more points that nerf the wall bots strategy, or could create some problems for the wall bot:

  1. If a bot simply got in the way of the large scissor wall while it was expanding, it could either prevent the scissor wall from extending any more, or make it drop in a spot that is not optimal for the wall bot alliance. Now I know you would say, “well our other defense bot could simply push the bot blocking the scissor wall from extending out of the way!”. This would not work due to the bot not allowing the scissor wall to extend having part of their bot still in their protected zone, making it so no contact from the other alliance is permitted.
  2. The flip out wall for the smaller zone looks fairly “dinky” in my opinion. It looks like it could genuinely be picked up by a vertical stacker with a claw and moved out of the way. Now if you say, “well we could just play defense on the bot trying to move the small wall”, I would state that it is basically impossible for the whole 1:45, as the small walls location being nested in a corner allows a team on the non wall bot alliance to access the wall easily even if being pushed into the corner. This opens a strategy for the non wall bot alliance to score their one stack in the large zone during auton, but have their partner hold onto their stack of 8 instead of scoring it in the small zone in auton. Then, at the beginning of driver, they score that stack into the large zone as well and then the alliance works to stack one more stack, move the small wall out of the wall, then score it in that zone. This strategy is more flawed in my opinion, but can still work.

Either way, I stated on the cast that I believed the wall bot can beat anyone, but also lose to anyone. I still agree with this and think that there are a few ways your design could be improved. If the wall bot could score cubes after deploying the walls, I believe they will become a lot more powerful and the strategy would be harder to beat. But for now, I don’t see the point values adding up for me to be able to endorse wall bots.


I would like to note a scenario about zone camping. Because the tethered bots can move with the walls and deploy at will, they have the ability to negate a lot of counter maneuvers. Say both bots camp both zones - no scoring occurs. Now one leaves to collect cubes, one robot can now deploy one wall. Now the other robot has to move if the collecting robot wants to score. At this point, the second wall can be deployed or the bot that has deployed already can lock down the collecting robot defensively. The wallbot was designed in the separate, controlled deploy to force 1v0 situations.

Also, about the expanding x-drive, we did test tray style robots against it, and we found that the expanding quality of it is extremely effective for defense despite the x-drive’s speed. Being able to setup screens while a robot is collecting allows this accordion drive to shut said robot away from even nearing a zone, especially since the zone area is a small, easily screenable area(essentially setting up a moving wall between a robot and it’s goal).


For your first point, most tray bots already have their stack done for the small zone in auton. So one robot on the non wall bot alliance could zone camp the large zone while their alliance partner picks up cubes to put into the large zone.

For your second point, my point on a chaotic field is still applicable. There will still be 5 robots essentially grouped together on one side of the field when the non wall bot alliance is trying to play defense on the wall bots partner. This will lead to too much chaos for the wall bots partner to get into a rhythm to be able to intake AND score 19 cubes within driver control as long as the non wall bot alliance plays it correctly.

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Well, only if they play it correctly.
The adaptiveness of this design also makes the wallbot unpredictable. The only truly effective way to beat a wallbot like this is with dedicated countermeasures.
It’s just that countermeasures can easily null the wallbot. But that’s still a win for team norCal so I’ll give that to them :unamused:

I think that well designed and thought out wall bots will be an important aspect of this season however what if after scoring for autonomous, the opposing alliance was to stay in front of their score zone. I you pushed their robot further back there would be a risk of forcing them to hit their stack of cubes and you would be disqualified. it also gives the opposing team an easier time pushing you walls out of place and negating their effect. Although this strategy would require planning and on the fly coding i could result in the effect of your robots being negated which would end up as a 2v1 against you. I feel that wall bot strategy could be effective however its a little too instance specific for me. I appreciate the reveal as I feel that it will help teams prepare to counter wall bots.