Each player uses a pair of two-axis control sticks and a foot pedal to operate a cable-driven tentacle with a gripper on the end. These are two stage tentacles, meaning that the top and bottom halves are independently controlled. The tentacles consist of a series of laminated foam discs clued onto bicycle cable sleeves. The cables are open in the section they control, and operate in a push-pull arrangement. The spring-loaded grippers are operated by the foot pedals, with a single cable running down the center of the tentacle.
The game looks quite fun and challenging, and we can imagine it being even more entertaining with teams of two or three people operating each tentacle. Add a bit of alcohol to adult players, and it might become downright hilarious, although the mechanisms would need to be beefed up a bit to survive that level of punishment.
I was always a sucker for art classes in my early days. There was something special about getting personal instruction while having those raw materials in your hands at the same time. Maybe it was the patient voice of the teacher or the taste of the crayons that finally got to my head. Either way, I started thinking: “I want to do this; I want to teach this stuff.”
Last year at Hackaday Superconference I got my chance. Hardware workshops with real hardware were so rare; I just had to bring one to the table! What follows is my tale of joys and woes bringing together a crew to take their first few steps into the world of cable-driven animatronics. If you’re thinking about getting your feet wet with teaching your own hardware workshop, read on. I’ve packed this story with as much of my own learnings as I could to set you on a path to success.
Welcome back to the final chapter in our journey exploring two-stage tentacle mechanisms. This is where we arm you with the tools and techniques to get one of these cretins alive-and-kicking in your livingroom. In this last installment, I’ll guide us through the steps of building our very own tentacle and controller identical to one we’ve been discussing in the last few weeks. As promised, this post comes with a few bonuses:
Depending on your situation, some design files may be more important than others. If you just want to get parts made, odds are good that you can simply cut the pre-offset DXFs from the right plate thicknesses and get rolling. Of course, if you need to tune the files for a laser with a slightly different beam diameter, I’ve included the original DXFs for good measure. For the heavy-hitters, I’ve also included the original files if there’s something about this design that just deserves a tweak or two. Have at it! (And, of course, let us know how you improve it!)
Ok, now that we’ve got the parts on-hand in a pile of pieces,let’s walk through the last-mile tweaks to making this puppet work: assembly and tuning. At this point, we’ve got a collection of parts, some laser-cut, some off the shelf. Now it’s time to string them together.
A few weeks back, we got a taste for two-stage tentacle mechanisms. It’s a look at how to make a seemily complicated mechanism a lot less mysterious. This week, we’ll take a close look at one (of many) methods for puppeteering these beasts by hand. Best of all, it’s a method you can assemble at home!
Without a control scheme, our homebrew tentacle can only “squirm around” about as much as an overcooked noodle. It’s pretty useless without some sort of control mechanism to keep all the cables in check at proper tension. Since the tentacle’s motion is driven by nothing more than four cable pairs, it’s not too difficult to start imagining a few hobby servos and pulleys doing the job. To get us started, though, I’ve opted for hand controllers just like the puppeteers of the film industry.
Enter Manual Control
Hand controllers? Of all the possibilities offered by electronics, why select such an electronics-devoid caveman approach? Fear not. Hand controllers offer us a unique set of opportunities that aren’t easy to achieve with most alternatives.
What’s not to love about animatronics? Just peel back any puppet’s silicone skin to uncover a cluster of mechatronic wizardry that gives it a life on the big screen. I’ve been hunting online for a good intro to these beasts, but I’ve only turned up one detailed resource–albeit a pretty good one–from the Stan Winston Tutorials series. Only 30 seconds into the intro video, I could feel those tentacles waking up my lowest and most gutteral urge to create physical things. Like it or not, I was hooked; I just had to build one… or a few. This is how you built a very real animatronic tentacle.
If you’re getting started in this realm, I’ll be honest: the Stan Winston Tutorial is actually a great place to start. In about two hours, instructor Richard Landon covers the mindset, the set of go-to components, and the techniques for fabricating a tentacle mechanism with a set of garage tools–not to mention giving us tons of real-film examples along the way .
We also get a sneak peek into how we might build more complicated devices from the same basic techniques. I’d like to pick up exactly where he left off: 4-way two-stage tentacles. And, of course, if you’ve picked up on just how much I like a certain laser-cuttable plastic at this point, I’m going to put a modern twist on Landon’s design. These design tweaks should enable you to build your own tentacle and controller with nothing more but a few off-the-shelf parts, some Delrin, and a laser cutter… Ok, fine, a couple 3D printed parts managed to creep their way in too.
In a good-ol’ engineers-for-engineers fashion, I’m doing something a little different for this post: I’m finishing off this series with a set of assembly videos, a BOM, and the original CAD files to make that beast on the front page come to life. As for why, I figured: why not? Even though these mechanisms have lived in the robotics community and film industry for years, they’re still lacking the treatment of a solid, open design. This is my first shot at closing that gap. Get yourself a cup of coffee. I’m about to give you every bleeding detail on the-how-and-why behind these beasts.