1471A Toss Up Wallbot Reveal "Apophis" AKA The Quadropus

This is the reveal for the wallbot we brought to Worlds. As far as we know, this is the largest robot in VEX history. Sadly we do not have any footage of it, but you can check out the livestream archives from worlds if you’d like to see. Our final match was Q195 in the Engineering division. Pictures are here: https://www.flickr.com/photos/123583170@N08/sets/72157644089099400/

This robot was built in about two months. We worked on it in the background while we competed with our offensive bot to get qualified for worlds. The goal of the wallbot was to block the opponents from the cylinders, but given the way the robot came out a lot had to be done to make that actually help our team.

At the start of the autonomous period, the two long linear expansions expand from 18" to a length of about 12 feet in the space of about one second. Yes, ONE second. This was an extremely fast expansion requiring four pistons to release and nearly 200 rubber bands by the end of worlds to actually expand fully. Those 200 rubber bands needed to be replaced before every single match, because they wore out with just a single expansion. Additionally, standard #32 rubber bands did not stretch to 17.5" without breaking, so we had to pre-stretch every single one of the 2000 rubber bands we used at worlds.

Additionally, our “minibot” drives off the top into the goal zone and our “microbot” drives into the middle zone at the start of auto as well.

We did not want to make the entire robot move forward so that our partner could pass through from the hanging zone to the goal zone because we knew the robot would be very unreliable that way, so we had to improvise. We built an entire side roller robot capable of playing buckies and big balls with 8 motors. It was only 10.5" tall and could still reach the cylinders. This was connected through the C channel “umbilical cord” seen in the photos. The goal was for the partner to pass us objects over the main “wall” base, then we would score them with the “minibot.”

We felt that we needed to protect our partner from the opponents so that they would not get defensed, though we did reconsider this during worlds. However, as you can see the robot shoots two linear “spears” out at the start of the match. The one on the hanging zone side is shorter, and there is a double piston assembly on the front/bottom that pushes it out and into the wall to make the geometry work out on the field.

What an average onlooker might not realize is that when this robot plays red and blue, the hanging zone expansion and goal zone expansion would have to switch places. Thus, even though only the hanging zone side needs to “pop” out to the side while expanding, and even though the hanging zone expansion needs to be shorter but also more powerful to get over the bump, the two linear slide racks on this robot are actually exactly the same.

A system of mechanical stops that could be switched between matches was created such that we could choose which spear would be for the hanging zone and which would “pop” out to the side while expanding. Other things that had to be switched for sides include the ENTIRE umbilical cord for the minibot as well as the direction of the chute the partners pass the balls over. The color switch usually took about 20 minutes between matches.

The “microbot” was created because we knew we really only needed 8 motors for the minibot and we wanted to try to make a difference with the last 2 of our 10. We built a small, agile robot with those two motors and deployed it into the middle zone with another umbilical cord behind it. Its goal was to do just about anything, wreak as much havoc as possible, etc. We never really expected it to be a game changer, but we figured anything this little guy could buy us would definitely be worth it, so we built it. Problem was, since the Cortex was on the minibot, this microbot was separated from the brain by about 30 feet of wire. Turns out, if you try to run a motor about 30 feet away from the Cortex, it doesn’t work very well. We solved this problem by installing the power expander inside the tiny microbot, meaning the only thing that had to go 30 feet was the signal. The power for the motors only had to travel from the power expander to the motors. This solution worked very well. The microbot was definitely silly and we appreciated that.

We had some issues at the beginning of the event. The expansions did not always deploy all the way right at the start, and a couple of teams managed to drive over our expansions which was one of the last things we worried would happen. Obviously this was not ideal, but we worked hard to get it fixed. The expansions got tuned up relatively quickly. We added more rubber bands and got the pneumatic pins that released them working better. We completely de-greased and re-greased our entire slide racks each night.

We got it fixed by Saturday morning and added in some hardware that actually made it impossible for anyone to drive over the walls in our last two matches but it was too late to show what our robot could do. We had several matches near the end where our robot deployed perfectly, scored autonomous points, and blocked the goal zone off.

The hanging zone wall was there to keep the opponents from 2v1 defending our partner. That being said, by alliance selection we had decided that we would be willing to leave that wall in and allow a strong alliance partner to have free reign of the field because we believed they would probably be capable of holding their own against the opponents.

We were not picked, probably because we had some bad matches near the beginning and hadn’t shown a strong enough case for our robot’s strength. This was a rushed 6 week build with no cad and several hiccups building the 26 sections of the linear slides. We fabricated nearly 200 brackets out of steel plate on a vise with two bends in each finding the perfect design for the front and back stops for our slides and the rubber band holders. We also went through about 2,000 rubber bands at worlds- every one of which had been prestretched ahead of time to be able to stretch to the 18" length of our slides without snapping. We used an entire tube of grease redoing our slides each night before the next day and spent over $500 on linear slides building this robot.

This robot was a massive engineering challenge, but we wanted to see if we could do it. I am very proud of the team and of this robot and I’m glad we chose to build something unique.

We may not have won that many matches, but I think the robot excited a lot of people and drew crowds to our booth almost constantly throughout worlds. People came to see our matches just because we built three robots in one and they wanted to see it. It was a great experience, definitely a lot more fun than the scoring robot we built last year. We won the engineering division Create Award and made Karthik appear speechless at our match, and that’s enough to satisfy us for this trip to worlds. :slight_smile:

We will be in college next year, but this was our third year building a wallbot and it won’t be our last. We built a scoring wallbot for gateway, a 12 foot double trough blocker that opened in 8 seconds for sack attack, and then this ridiculous robot that took about a second to open and expand thirteen feet. I have no idea how we will raise the bar for ourselves again :stuck_out_tongue:

Thanks for all the compliments we received on our robot at worlds :slight_smile:

Any questions or comments would be much appreciated.

Pics :stuck_out_tongue: https://www.flickr.com/photos/123583170@N08/sets/72157644089099400/


Easily my favourite robot in Anaheim. Thanks for reminding us of what teams can accomplish if they aren’t afraid to think outside the box. This design was refreshing to see, both for its creativity and effectiveness.


Wow. That means so much coming from the man who wrote the book… Literally. Thanks a lot Karthik :slight_smile:

We really did spend almost that entire match watching your reaction instead of, well, you know, playing the match . . . Not really, but that was awesome :smiley:

I was only watching his face as well :slight_smile:

Our team competed in Arizona throughout the season with a scoring bot that resembled most of the robots I saw at the World Championship. Sure, it was great to win every tournament along with several other awards, but the fact that most teams in the entire world had the same basic design was a bit boring. I felt like the game of this season turned into “who can build the best side roller bot”, which grew trivial after a while. When we initially came up with this design, we knew it would be hard to carry out, but we did it anyway.

Building Apophis and bringing it to the World Championship was the best decision our team made all season. So many teams came to our booth to see and talk about our robot. After seeing the amazement and the admiration from so many different people, I personally was completely satisfied. I am so happy that our team, 1471A, was able to bring a new idea to the game. Winning every single match at the Championships could not have made me happier than sharing our contraption with people who love robotics as much as we do.

When I saw Karthik’s jaw drop at the beginning of our match, I knew we had done something completely different and original. Nothing else could have provided me that level of gratification. I cannot wait to start a college team next year and come back to the World Championship. Not only to compete with new crazy robots, but to see other teams try new ideas just as we did. :slight_smile:



Wow! That"s crazy!

I would have liked to see the Lynfield (and ex Lynfield) teams win at worlds, but missing this robot here is what makes me sad that I did not attend. I had no idea until seeing this reveal that the minibot (not microbot) was part of your robot. I had only noticed the microbot on the stream. Very well done. You’ve achieved something exceedingly impressive.

Very impressive. I know how tough it is to build a wallbot this complicated, and I can’t pull it off myself. Just having it fit inside 18" is enough of a challenge, plus you have to make it expand ultra fast, and you guys decided to build an attached scoring robot on top of all of that. Hats off.

Do you have a picture of how it looks when you start the match or before it deploys?

I should have something Noah. I’ll look when I get home in about two hours :slight_smile:

Here is the most complete picture I have of it closed. It provides a unique view of the double piston “pop out” bar that is connected between the two linear expansions. The linear expansions are axled in the back and free to rotate about 15 degrees each. We controlled which one would pop out by bolting down the one we didn’t want to pop out, so the double-piston bar in the front would push the popping out one off of the not popping out one. Note the absence of the microbot and much of the wiring and tubing, and that the piston powered releases for the linear expansions are an old version that was replaced with this one:

Album: Building Apophis

This album contains many pictures of the build process. You can see a lot of different versions of some parts. We did not have any formal design going in because we are terrible at CAD. We just knew “about” where we wanted everything to be and most of how it would work. Wallbot building can be very difficult so there are several versions of the front latches to be seen, as well as the microbot, the umbilical cords, the linear slide racks, etc :slight_smile:


Such an annoying robot to play against! We scored a grand total of 30 points against you… sigh…

Seriously though, this robot is incredible. Such a great bot and really amazing to see it work well! I hope I see you guys next year.


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I was looking at the standings where they were also displaying the webcasts for all the divisions. You guys happened to be playing and I was told earlier that you guys had a wallbot, but I was confused because all I saw was a normal scoring robot with the 1471A plate on it. When the camera zoomed out though, I couldn’t believe what I was seeing.

I have seen all three reveals for the three wallbots that you guys have built and they are some of my favourite robots. Good thing 1492X’s traction wheel spared us from having to play against you guys in Gateway :wink:

I’m curious about your release? Based on the pictures you basically had two cylinders that were mounted to a linear slide, and when the pistons extended 2" that would pull the linear slide out of it’s partner?

Most people won’t realize this but that is the most difficult part of a robot like this IMO because the cylinders have to overcome a lot of stored energy and friction to release.


And then we went and got ourselves DQed after the match against you :stuck_out_tongue: that was literally the first good robot we ever built, so I’m not surprised that we got over zealous and didn’t have good strategy. I liked that wallbot a lot though :slight_smile:

The top of the piston moves up, pulling that 3 hole wide piece of c channel that’s attached to the slide up. That part is what keeps the expansions from releasing until it pulls up out of the way. It was definitely a difficult thing to get right as we are dealing with a LOT of force. The parts bent a lot if we weren’t careful and it ended up requiring a rubber band assist to help the pistons pull up. However, the slide racks themselves were truly the most difficult part of this robot :stuck_out_tongue:

to bad it couldn’t hang :wink: just kidding. I just find it so unrealistic and impossible to create wall bots. i always imagine offensive strategies and such. but this is outstanding. I cant wait to see what you’ll come up with next!

Yeah, I mean by the end of worlds it only weighed 50 pounds. We should have added more weight. Then it could hang. :3

Wow!!! An absolutely amazing robot!

After seeing this, I have reconsidered the Skyrise idea I had, and I think I am going to consider a defensive design…

Just wondering, why did you use the elastics instead of latex tubing? I have found that latex tubing can be stretched a lot, and doesn’t wear out as quickly.

Thanks! That was part of the goal. I hope to see some more defense bots this year. Just know what you’re in for, this ain’t easy :stuck_out_tongue:

The problem with the latex tubing was that when stretched to this length, it either snapped, was super thin and about to snap, or untied itself. It was also extremely difficult to change and didn’t have as much power or adjustability as the rubber bands. We moved to rubber bands and were very happy.