hand

42 Articles

Generating Motion Via Nitinol Wires

December 2, 2023 by 13 Comments

Generally, when we’re looking to build something that moves we reach for motors, servos, or steppers — which ultimately are all just variations on the same concept. But there are other methods of locomotion available. As [Jamie Matthews] demonstrates, Nitinol wires can be another way to help get things moving.

Nitinol is a type of metal wire made of nickel and titanium that is also known as “memory wire”, because it can remember its former shape and transition back to it with a temperature change. [Jamie] uses this property to create a simple hand that is actuated by pieces of wire sourced from Amazon. This is actually a neat way to go, as it goes some way to mimicking how our own hands are moved by our tendons.

[Jamie] does a great job of explaining how to get started with Nitinol and how it works in a practical sense. We’ve seen it put to some wacky uses before, too, such as the basis for an airless tire.

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Big 3D Printed Hand Uses Big Servos, Naturally

September 1, 2023 by 15 Comments

[Ivan Miranda] isn’t afraid to dream big, and hopes to soon build a 3D printed giant robot he can ride around on. As the first step towards that goal, he’s built a giant printed hand big enough to hold a basketball.

The hand has fingers with several jointed segments, inspired by those wooden hand models sold as home decor at IKEA. The fingers are controlled via a toothed belt system, with two beefy 11 kg servos responsible for flexing each individual finger joint. A third 25 kg servo flexes the finger as a whole. [Ivan] does a good job of hiding the mechanics and wiring inside the structure of the hand itself, making an attractive robot appendage.

As with many such projects, control is where things get actually difficult. It’s one thing to make a robot hand flex its fingers in and out, and another thing to make it move in a useful, coordinated fashion. Regardless, [Ivan] is able to have the hand grip various objects, in part due to the usefulness of the hand’s opposable thumb. Future plans involve adding positional feedback to improve the finesse of the control system.

Building a good robot hand is no mean feat, and it remains one of the challenges behind building capable humanoid robots. Video after the break.

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Hackaday Links: February 12, 2023

February 12, 2023 by 24 Comments

So, maybe right now isn’t the best time to get into the high-altitude ballooning hobby? At least in the US, which with the downing of another — whatever? — over Alaska, seems to have taken a “Sidewinders first, threat identification later” approach to anything that floats by. The latest incident involved an aircraft of unknown type, described as “the size of a small car” — there’s that units problem again — that was operating over Prudhoe Bay off the northern coast of Alaska. The reason that was given for this one earning a Sidewinder was that it was operating much lower than the balloon from last week, only about 40,000 feet, which is well within the ceiling of commercial aviation. It was also over sea ice at the time of the shootdown, making the chance of bothering anyone besides a polar bear unlikely. We’re not taking any political position on this whole thing, but there certainly are engineering and technical aspects of these shootdowns that are pretty interesting, as well as the aforementioned potential for liability if your HAB goes astray. Nobody ever really benefits from having an international incident on their resume, after all.

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Adding Brakes To Actuated Fingers

November 8, 2021 by 10 Comments

Building exoskeletons for people is a rapidly growing branch of robotics. Whether it’s improving the natural abilities of humans with added strength or helping those with disabilities, the field has plenty of room for new inventions for the augmentation of humans. One of the latest comes to us from a team out of the University of Chicago who recently demonstrated a method of adding brakes to a robotic glove which gives impressive digital control (PDF warning).

The robotic glove is known as DextrEMS but doesn’t actually move the fingers itself. That is handled by a series of electrodes on the forearm which stimulate the finger muscles using Electrical Muscle Stimulation (EMS), hence the name. The problem with EMS for manipulating fingers is that the precision isn’t that great and it tends to cause oscillations. That’s where the glove comes in: each finger includes a series of ratcheting mechanisms that act as brakes which can position the fingers precisely enough to make intelligible signs in sign language or even play a guitar or piano.

For anyone interested in robotics or exoskeletons, the white paper is worth a read. Adding this level of precision to an exoskeleton that manipulates something as small as the fingers opens up a brave new world of robotics, but if you’re looking for something that operates on the scale of an entire human body, take a look at this full-size strength-multiplying exoskeleton that can help you lift superhuman amounts of weight.

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Making A Metal Hand Doorknob

September 24, 2021 by 23 Comments

Regular doorknobs are widely reviled for their bare simplicity, but by and large society has so many other problems that it never really comes up in day to day conversation. Fear not, however, for [Matthew] has created something altogether more special: a doorknob in the shape of his own outstretched hand.

The build was inspired by a similar doorknob at the WNDR museum in Chicago, and its one you can recreate yourself, too. It’s achieved through a multi-stage mold making process. [Matthew]’s first step was to make a flexible mold of his hand using Perfect Mold alginate material to do so.

Once solidified, [Matthew’s] hand was removed and the mold filled with wax. The wax duplicate of [Matthew]’s hand was then used to create an investment plaster mold for casting metal. Vents were added in the end of each fingertip in the mold to allow molten metal to effectively fill the entire cavity.

Once the investment mold was solid and dry, the wax was melted out and it was ready for casting. A propane furnace was used to melt the casting metal and fill the mold using a simple gravity casting method. [Matthew] ended up making two hands, one in aluminium and one in copper. Some cleanup with grinders and a wire wheel, and a replica of [Matthew]’s hand was in his hands!

The finished piece looks great attached to a door knob, and we’re sure it’s quite satisfying shaking hands with your hefty metal self every time you open the door. It bears noting that the same techniques can be used with 3D printing, too! If you pull off your own great home casting project, be sure to drop us a line. Video after the break.

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Leap Motion Controls Hands With No Glove

May 8, 2021 by No comments

It isn’t uncommon to see a robot hand-controlled with a glove to mimic a user’s motion. [All Parts Combined] has a different method. Using a Leap Motion controller, he can record hand motions with no glove and then play them back to the robot hand at will. You can see the project in the video, below.

The project seems straightforward enough, but apparently, the Leap documentation isn’t the best. Since he worked it out, though, you might find the code useful.

An 8266 runs everything, although you could probably get by with less. The Leap provides more data than the hand has servos, so there was a bit of algorithm development.

We picked up a few tips about building flexible fingers using heated vinyl tubing. Never know when that’s going to come in handy — no pun intended. The cardboard construction isn’t going to be pretty, but a glove cover works well. You could probably 3D print something, too.

The Unity app will drive the hand live or can playback one of the five recorded routines. You can see how the record and playback work on the video.

This reminded us of another robot hand project, this one 3D printed. We’ve seen more traditional robot arms moving with a Leap before, too. Continue reading “Leap Motion Controls Hands With No Glove” →

Meticulous Bionic Hand

November 12, 2020 by 12 Comments

[Will Cogley] is slowly but surely crafting a beautiful bionic hand. (Video, embedded below.) The sheer amount of engineering and thought that went into the design is incredible. Those who take their hands for granted often don’t consider the different ways that their digits can move. There is lateral movement, rotation, flexion, and extension. Generally, [Will] tries to design mechanisms with parts that can be 3D printed or sourced easily. This constrains the hand to things like servos, cable actuation, or direct drive.

However, the thumb has a particularly tricky range of motion. So for the thumb [Will] designed to use a worm geared approach to produce the flexing and extension motion of the thumb. These gears need to be machined in order to stand up to the load. A small side 3d printed gear that connects to the main worm gear is connected to a potentiometer to form the feedback loop. Since it isn’t bearing any load, it can be 3d printed. While there are hundreds of little tiny problems still left to fix, the big problems left are wire management, finalizing the IP (Interphalangeal) joints, and attaching the whole assembly to the forearm.

All the step files, significants amounts of research, and definitions are all on [Will’s] GitHub. If you’re looking into creating any sort of hand prosthetic, the research and attention [Will] has put into this is work incorporating into your project. We’ve seen bionic hands before as well as aluminum finger replacements, but this is a whole hand with fantastic range and fidelity.

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