A robot arm basically has a rocket equation problem. Each motor closer to the root must support the weight of all the ones above it. An advantage of cable robots is that the motors don’t have to be on the moving part. In a CDPR you can place all... the main motors on the wall, and they can all be the same part with the same torque. You don’t even have to place one in each corner. In theory you could have a cable robot in every room in your house and put all the motors in the basement with the lines passing through PTFE tubes in the walls. In Stringman, each anchor has a pair of motors, one direct, and one indirect, routed though a ceramic fishing eyelet in another corner. Consolidating the motors into fewer components drives the cost down, but two camera angles still gives a good view of the room. The spool motors are Damiao direct drive actuators (DM-H6215). And unlike an arm, they’re all sharing the load, so they can be one of the smaller models, and having no reducer keeps the noise to a minimum. If you want a cable robot in every room in your house by the way, I’m your guy.show more

I’ve been dreaming about something like this for years

Would you like to try building one?

@macjshiggins Yes..

If you have a set of m3 bolts you can assemble most of the gripper without motors to see how it works. You can also just print Anchor/Anchor - cover top.stl in white to get an idea of how it would look on your wall. I have one hardware kit left, after that I'll have more when motors arrive from damiao in late june. I'd be happy to help with the build process, you can dm me or ask on discord

Cable-driven robots are still one of the most underrated architectures in robotics. The scalability potential is huge.

Yes but which animal's reproductive organ is it shaped like?

I need this for my church I run the sound at we can never can get audio on prayer requests would be hilarious to have an NFL sky cam in a 150+/- member Baptist church🤣

Well the patent on the sky cam did expire and maybe there is a market for the scale you're talking about. You'd want to have a nice gimballed camera on the end platform and like skycam you'd probably just power it from a battery. In stringman I deliver power along one of the cables but I think the resistance and the weight become a problem at a gymnasium or sanctuary scale. Probably $5000 for the cdpr system and another $5000 for the gimbal camera.

I love it, but what is the killer app? Picking up trash? It's only going to work in the middle of the room. If you stacked two of them, you might be able to control a short arm through enough degrees with sufficient strength to open/close some very cooperative drawers, maybe.

Yep, picking up trash, laundry, and toys. I'm not trying to make it do everything. Just a few things well. Put things in a basket so you can walk through the room (kids are pretty messy)

@atthatmatt Would be cool if it could auto-clean a whole city square overnight e.g. after a festival. Nice concept!

@atthatmatt That's a very interesting idea. You only need a couple of utility poles or buildings to hang it from. I thought about an outdoor installation at a larger scale. Are you looking at the much more camera resolution is needed but there are some interesting applications.

And what about biological limbs? The muscles that move your fingers sit mostly in your forearm, not your fingers—fingers are almost entirely bone, tendon, and ligament, driven remotely by tendons (cables) running over the wrist. This cable robot is copying the evolved solution.

DUDE IVE SCRIBBLED THIS EXACT TYPE OF HOME ROBOT SOLUTION OUT BEFORE OMG AND YOUAR E DOING IT

i love the concept except how do you solve for ceiling fans? im not gonna give up ceiling fans for this.

Mount it at the height of the ceiling fan or lower. So far this hasn't been a problem in any of the rooms I have with ceiling fans. But I think if you had a really low fan it might be.

probably wouldnt be a problem in newer built homes, unfortunately my house doesnt have very high ceilings so thats not an option for people in my situation. very cool idea tho

Cats are gonna love hunting the floating arm

This is awesome Nathaniel! Can't wait till I get mine!!

Couple ideas: 1. Add a feather toy for cats 2. Hook for your roomba to let it do landings and the second story of your home. Maybe even let your roomba do table tops and counters

Payload limit on this one is 4 kg and the knots are designed to fail before the mounts pull out of the wall. If a certain amount of tension is reached somehow without the knots failing the motors switch to a damped mode. So if somehow you become entangled in the wire, just pull hard.

In serial robot arms every joint closer to the base must carry the mass and inertia of everything above it, which creates a steep scaling penalty in torque, stiffness, and cost. Cable-driven parallel robots break this by moving actuation off the arm, so only lightweight cables move while motors stay fixed in the environment, drastically reducing moving inertia and improving speed and efficiency. But the trade-off is not free you replace mechanical scaling problems with control complexity, because stability now depends on precise multi-cable tension management and real-time system geometry instead of rigid links.

This is awesome! A little similar to why humans have tendons.

scrolling and saw a cable robot and crown molding in the same image, fantastic

Innovative. Though you’ve seen that movie “Cube”, right? The bit at the start where the guy gets sliced into pieces. I’m getting echoes of that with these wires whizzing around at head height.

Yes, and I'm not totally sure how best to address that concern. I hope you'll believe me when I say it's not a big deal (you've walked in front of fishermen at the shore before right?) But the fear is real and many people are put off by it. All I know how to say is that you get used to it easily and I'm hoping to offer a level of convenience that makes the wires worth the trouble.

Look up how the man behind leaded gasoline died.

It dont have to, people just elect to. Depending on the job, shafts and u-joints could be used in many cases and would reduce motor shock on arm impacts.

Can this be stable enough for a gimballed camera? I was gonna try streaming electronics stuff a few years ago and i wanted an overhead camera that i could freely reposition, to show a wider angle of what's on my desk.

wow thats a really clever iddea!!! super cool, insta follow

Very cool! I might try to build one.

Please see here for the build guides 3d prints are in the download section and I'm happy to help out during the build process if you do end up giving it a try.

This is cool. A thought if I may. What if you had a second set of motors that controlled the z axis and kept the x y axes taught at ceiling height. If I've understood the mechanics correctly, that would let the head get right up to the walls on all 4 sides of the room.

That was the layout of the first prototype roughly. I wanted the lateral lines to stay high, always above head level if possible. But several factors led to me swapping the vertical "winch" element with a 50cm plastic tube. first, the closer to the ceiling the box gets, the more errors in calibration and timing matter, making it difficult to precisely position it the higher it gets. Second, in this robot I supply power to the gripper from one of the support lines. That line had to wind around a small diameter spool in the gripper with a smaller slip ring and I became concerned about wire fatigue there. Fourth, I wanted a wrist DOF. the rigid tube gave me that but also making the rigid tube move up and down would have added complexity, noise, and weight. finally, I just lived with the wires for a while and realized that having them low sometimes when the robot was operating wasn't a big deal. I generally operate the bot when nobody is in the room and then park it up out of reach on a hook. The 50 cm vertical tube solved a bunch of these problems, while also still letting it get right next to furniture. Also the exact length needed to be known for accurate swing cancellation, and with the previous version I kept having to zero the winch line to find out how long it was at boot.

Similar story for future nanorobotics. Just there one wants's to avoid the volume of the motors inside the much smaller robotic stage rather than the mass of the motors that gets negligible because friction dictates slow speeds anyway & gemstone materials are stiffer than steel.

issues is one per room, kids seem to like accumulating stuff in interleading doorways

now just hang a flag off it when you leave for the day. 🤣 really cool.

how does it handle collision detection?

Not handled yet.

I like using the blocky square for location!

Great post dude!

I want this as a more realistic / useful version of the jarvis controlled robot arms in iron man. Like I want this in my shop. I want it to be controlled by a VLM and be like my shop buddy. realtime voice + vlm on a harness would be SICK AF. how do I do this.

I think that this is probably possible. Other people have asked me about this or just outright said they're going to do it. I think the right approach is to have a VLA or DIT that finds and picks up objects, and accepts a prompt from a higher level orchestration layer that decides what to do. Join in, get one! Try some shit

How would you then fold clothes out of a laundry 🧺 basket and put them away? Hang an hand/wrist/lower-arm mounted to an elbow on the pulley-bot? Could you have two? Moving the basket 🧺 from room to room would require ground-transport bots and the pulley-bots in other rooms. Pulley-bots mean planning your whole bot ecosystem differently. It’s a different way of thinking about how to do tasks & solve processes.👍

I think that folding is just outside of the scope of this robot. It kind of looks like self-contained folding tables with bi-manual arm setups are going to become a thing, so maybe stringman will just be able to bring clothes to the folding table robot. Still probably cheaper in total than a humanoid.

How long was it until someone ran into a cord?

About 20 times less often than someone stepping on a toy

Potentially dumb question, do you typically run these when the room is empty?

cables, like tendons?

I've seen this for loading forage wagons with silage at German farms. They use a scoop crane mounted on an iron rail.

Very nice. Store drop and place limbs for ground tasks. In a larger conveyer belt you could estimate a few working beds. Less movement to established work zones. Most tasks becoming less difficult with 2 limbs.

ISO 8373 An automatically controlled, reprogrammable, multipurpose manipulator, programmable in three or more axes, which can be either fixed in place or mobile, for use in industrial automation applications.