pic: Simple hook delivery system

This is the simple hook delivery system we built to allow our robot to scale the tower for Stronghold. The grappling hook is launched through a guiding hole in a piece of plastic (delrin, UHMW plastic, wood? whatever has low friction). The orange shaft is a piece of construction site fiberglass pole that you can get from home depot. A small piece of latex or rubber bands is used to propel it upward like a crossbow, and a pneumatic cylinder holds it in place.

We built our scaling mechanism over the course of friday and saturday morning at AZ North after the pit team ran out of stuff to work on. All of the materials can likely be found throughout the pits at a typical regional (at least, they were at our regional, that’s why we built it like this!)

Total weight of the components pictured is under 2 lbs.

Y’all are absolutely crazy. I love it. I caught some of the live stream; let me know if you have any prettier video available.

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I should have put a video link in the description… Here’s footage of the scaling from the side of the field during semis 1-2 at Las Vegas: https://www.youtube.com/watch?v=ojyvzLD55qM

It’s a mini-bot! :eek:

This is awesome! Did it ever miss the bar in matches/practicing on a bar? If it did, did it fall back onto the robot or break the extension length rule? Thanks!

Built at an event? That’s absolutely insane. How does the clamp stay open/shut (more worried about the shut part). Do you have any close up pictures of the system, particularly the rubber bands or latex you were talking about? And then how are you winching up? Is it a PTO or separate gearbox?

I know 118 did it already, but honestly, this one is so much cooler. Amazing work.

What is terrifying about this is that it could be cheesecaked on almost all stronhold robots. I bet cheesecaked scalers like this are going to be a familiar sight come Champs.

Amazing mechanism! Especially for something done over the course of a competition! Is that a shaft collar being used to attach the fiberglass on to the hook? Also, I’m not a hundred percent sure about this but, one of our mentors said that fiberglass was not legal for use, as it shatters if it breaks and can cause splinters if not handled correctly.

There are quite a few teams that haven’t utilised pneumatics this year, a Servo-motor actuation system could be used as a replacement for pneumatics

heh…if fiberglass were illegal, then a whole bunch of 842’s past robots would be illegal! since they had fiberglass chassis


I’m sad I don’t get to see it live in action. I guess we need to win so we can go to Champs so I can see it work!

I’m confused. How does your hook stay open till it clamps on? I know how the 118 style one works, but this one seems fundamentally different.

We had a few missed shots (some due to not being able to align correctly, since our bumpers can interfere with alliance partner bumpers when we’re all on the batter, and some due to week shots because we didn’t load it properly). The climbing rope tends to yank the grappler straight back at the robot, and it doesn’t stray far from our frame perimeter. As far as I know we never received a penalty for exceeding the 15" on a missed shot during the Vegas regional.

The best picture I have of the latex is in the image in the first post. On the grappler itself, the latex is looped in a way that keeps the grappler open, but as soon as it hits the pole the claws snap over center and the latex clamps them together.

Our gearbox was a toughbox nano with a 1/2" ratcheting wrench zip tied to the side: http://i.imgur.com/YwcDhV6.jpg

The 1/2" output shaft acts as the spool for the rope.

Great minds must think alike! We built a second one during the Vegas regional for cheese caking purposes and bagged it with the robot. :slight_smile:

The large shaft collar acts as a clamp to hold the 1/2" hex shaft onto the fiberglass rod. Generally fiberglass material has not been ruled as dangerous by inspectors, especially rods like the ones we used. Teams have been using them for years.

Open is easy, You can look at it and tell it’s an over-center mechanism. The back piece of latex tube would clearly hold it open under tension. I’m more curious about what moves the two halves far enough forward to break-over and snap shut. Is it just inertia when the middle hits the bar?


Even if it doesn’t hit a bar, the inertia of the two hooks makes them go over center when the grappler reaches the end of the rope.

Very cool.

What happens when it misses does it ever have the potential to go outside 15"?

How do you aim it?

How did you use the rubber band like a crossbow if it was inside of the pneumatic cylinder. Also could you fit under the low bar with it?

What I believe they did was use that red stick thing to push back an elastic band (probably surgical tubing), and then used the pneumatic cylinder to hold back the elastic band and keep it there until it was quickly released by actuating the cylinder.

I strongly suspect you haven’t tried to add a hanging mechanism to a robot that wasn’t designed for one within a 6 hour window before! It’s quite difficult. Getting the hook onto the bar is the easy part. Dropping in a winch, ensuring that winch either pulls from the robot’s CG or from multiple points on the robot, keeping the robot level on its way up, and programming make this a nontrivial task. I’m sure it’ll be done once or twice, but this won’t be commonplace, particularly for short robots.

The other reason this won’t be seen that often is that your second pick this year actually is really valuable and needs to play the game well, whereas in 2015 you could pick a robot that was a lot worse at playing the game in exchange for a robot that is easy to cheesecake.

The winch, I think, is the easy part: http://www.gearwrench.com/MagentoShare/media/catalog/product/cache/4/image/1200x1200/9df78eab33525d08d6e5fb8d27136e95/G/W/GW_85201_A_FRNT_MAIN.jpg

I agree that the longest part of the cheesecaking process would be locating it on the robot to align with the CG, though.

We’ll already have a motor/winch attached to the cheesecake version at champs. We had a BAG motor with a 90:1 reduction attached to the spare mechanism we made at Vegas and the entire thing (hook+launcher+winch) weighed in at 3.5 lbs. The BAG motor takes about 6-8 seconds to winch up and scale.

Not shown in the original picture is an eye bolt that goes through the end of the launching tube. If the rope for climbing is run through that fixed location near the top of the robot, there aren’t issues with CG.

I honestly don’t think it takes more than half an hour to install a mechanism like this on a robot and get it to work. It’s tough to do at a regional level since all three teams begin playing back to back elimination matches immediately, but at championships you have a bit more time and a 4th robot.