Flexures Make Robotic Fingers Simpler To Print

July 16, 2024 by Dan Maloney 6 Comments

Designing an anthropomorphic robotic hand seems to make a lot of sense — right up until the point that you realize just how complex the human hand is. What works well in bone and sinew often doesn’t translate well to servos and sensors, and even building a single mechanical finger can require dozens of parts.

Or, if you’re as clever about things as [Adrian Perez] is, only one part. His print-in-place robotic finger, adorably dubbed “Fingie,” is a huge step toward simplifying anthropomorphic manipulators. Fingie is printed in PLA and uses flexures for the three main joints of the finger, each of which consists of two separate and opposed coil springs. The flexures allow the phalanges to bend relative to each other in response to the motion of three separate tendons that extend through a channel on the palmar aspect of the finger, very much like the real thing.

The flexures eliminate the need for bearings at each joint and greatly decrease the complexity of the finger, but the model isn’t perfect. As [Adrian] points out, the off-center attachment for the tendons makes the finger tend to curl when the joints are in flexion, which isn’t how real fingers work. That should be a pretty easy fix, though. And while we appreciate the “one and done” nature of this print, we’d almost like to see the strap-like print-in-place tendons replaced with pieces of PLA filament added as a post-processing step, to make the finger more compact and perhaps easier to control.

Despite the shortcomings, and keeping in mind that this is clearly a proof of concept, we really like where [Adrian] is going with this, and we’re looking forward to seeing a hand with five Fingies, or four Fingies and a Thumbie. It stands to be vastly simpler than something like [Will Cogley]’s biomimetic hand, which while an absolute masterpiece of design, is pretty daunting for most of us to reproduce.

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The Gopher Revival Is Upon Us

December 29, 2023 by Jenny List 39 Comments

A maxim for anyone writing a web page in the mid 1990s was that it was good practice to bring the whole thing (including graphics) in at around 30 kB in size. It was a time when the protocol still had some pretence of efficient information delivery, when information was self-published, before huge corporations brought everything under their umbrellas.

Recently, this idea of the small web has been experiencing something of a quiet comeback. [Serge Zaitsev]’s essay takes us back to a time before the Internet as we know it was born, and reminds us of a few protocols that have fallen by the wayside. Finger or Gopher, both things we remember from our student days, but neither of which was a match for the browser.

All is not lost though, because the Gemini protocol is a more modern take on minimalist Internet information sharing. It’s something like the web, but intentionally without the layer upon layer of extraneous stuff, and it’s been slowly gathering some steam. Every time we look at its software list it becomes more extensive, and we live in hope that it might catch on for use with internet-connected microcontroller-based computing. The essay is a reminder that the internet doesn’t have to be the web, and doesn’t have to be bloated either.

Blood Pressure Monitor For Under $1

June 20, 2023 by Bryan Cockfield 22 Comments

Medical equipment is not generally known for being inexpensive, with various imaging systems usually weighing in at over a million dollars, and even relatively simpler pieces of technology like digital thermometers, stethoscopes, and pulse oximeters coming in somewhere around $50. As the general pace of technological improvement continues on we expect marginal decreases in costs, but every now and then a revolutionary piece of technology will drop the cost of something like a blood pressure monitor by over an order of magnitude.

Typically a blood pressure monitor involves a cuff that pressurizes against a patient’s arm, and measures the physical pressure of the blood as the heart forces blood through the area restricted by the cuff. But there are some ways to measure blood pressure by proxy, instead of directly. This device, a small piece of plastic with a cost of less than a dollar, attaches to a smartphone near the camera sensor and flashlight. By pressing a finger onto the device, the smartphone uses the flashlight and the camera in tandem to measure subtle changes in the skin, which can be processed in an app to approximate blood pressure.

The developers of this technology note that it’s not a one-to-one substitute for a traditional blood pressure monitor, but it is extremely helpful for those who might not be able to afford a normal monitor and who might otherwise go undiagnosed for high blood pressure. Almost half of adults in the US alone have issues relating to blood pressure, so just getting information at all is the hurdle this device is attempting to overcome. And, we’ll count it as a win any time medical technology becomes more accessible, more inexpensive, or more open-source.

A cinematic shot of the resulting prosthetic finger attached to the glove

Missing Finger Gets A Simple Yet Fancy Replacement

March 3, 2023 by Arya Voronova 27 Comments

The possibility of a table saw accident is low, but never zero — and [Nerdforge] has lost a finger to this ever-useful but dangerous contraption. For a right-handed person, losing the left hand pinky might not sound like much, but the incident involved some nerve damage as well, making inaccessible a range of everyday motions we take for granted. For instance, holding a smartphone or a pile of small objects without dropping them. As a hacker, [Nerdforge] decided to investigate just how much she could do about it.

On Thingiverse, she’s hit a jackpot: a parametric prosthetic finger project by [Nicholas Brookins], and in no time, printed the first version in resin. The mechanics of the project are impressive in their simplicity — when you close your hand, the finger closes too. Meant to be as simple as possible, this project only requires a wrist mount and some fishing line. From there, what could she improve upon? Aside from some test fits, the new finger could use a better mounting system, it could stand looking better, and of course, it could use some lights.

For a start, [Nerdforge] redesigned the mount so that the finger would instead fasten onto a newly-fingerless glove, with a few plastic parts attached into that. Those plastic parts turned out to be a perfect spot for a CR2032 battery holder and a microswitch, wired up to a piece of LED filament inserted into the tip of the finger. As for the looks, some metal-finish paint was found to work wonders – moving the glove’s exterior from the “printed project” territory into the “futuristic movie prop” area.

The finger turned out to be a resounding success, restoring the ability to hold small objects in ways that the accident made cumbersome. It doesn’t provide much in terms of mechanical strength, but it wasn’t meant to do that. Now, [Nerdforge] has hacked back some of her hand’s features, and we have yet another success story for all the finger-deficient hackers among us. Hacker-built prosthetics have been a staple of Hackaday, with the OpenBionics project in particular being a highlight of 2015 Hackaday Prize — an endearing demonstration of hackers’ resilience.

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Adding Brakes To Actuated Fingers

November 8, 2021 by Bryan Cockfield 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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Dexterity Hand Is A Configurable Prosthetic Hand

December 14, 2018 by Bryan Cockfield 5 Comments

One of the interesting benefits of the 3D printing revolution is the dramatic increase in availability of prosthetics for people with virtually any need. With a little bit of research, a 3D printer, and some trial and error, virtually anyone can build a prototype prosthetic to fit them specifically rather than spend thousands of dollars for one from a medical professional. [Dominick Scalise] is attempting to flesh out this idea with a prosthetic hand that he hopes will be a useful prosthetic in itself, but also a platform for others to build on or take ideas from.

His hand is explained in great detail in a series of videos on YouTube. The idea that sets this prosthetic apart from others, however, is its impressive configurability while not relying on servos or other electronics to control the device. The wearer would use their other hand to set the dexterity hand up for whatever task they need to perform, and then perform that task. Its versatility is thanks to a unique style of locks and tensioners which allow the hand to be positioned in various ways, and then squeezed to operate the hand. It seems like a skilled user can configure the hand rapidly, although they must have a way to squeeze the hand to operate it, or someone will need to develop an interface of some sort for people without needing to squeeze it.

To that end, the files for making your own hand are available on Thingiverse. [Dominick] hopes that his project will spark some collaboration and development, using this hand as a basis for building other low-cost 3D printed prosthetics. There are many good ideas from this project that could translate well into other areas of prosthetics, and putting it all out there will hopefully spur more growth in this area. We’ve already seen similar-looking hands that have different methods of actuation, and both projects could benefit from sharing ideas with each other.

Thanks to [mmemetea] for the tip!

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The Battle Between Robot Harmonica And Machine Finger Rages On

December 13, 2018 by Lewin Day 12 Comments

When asking the question “Do humans dream of machines?”, it’s natural to think of the feverish excitement ahead of an iPhone or Playstation launch, followed by lines around the block of enthusiastic campers, eager to get their hands on the latest hardware as soon as is humanly possible. However, it’s also the title of an art piece by [Jonghong Park], and is deserving of further contemplation. (Video after the break.)

The art piece consists of a series of eight tiny harmonicas, which are in turn, played by eight fans, which appear to have been cribbed from a low-power graphics card design. Each harmonica in turn has a microphone fitted, which, when it picks up a loud enough signal, causes an Arduino Nano to actuate a mechanical finger which slows the fan down until the noise stops. It’s the mechanical equivalent of a stern look from a parent to a noisy child. Then, the cycle begins again.

The build is very much of the type we see in the art world – put together as simply as possible, with eight Arduinos running the eight harmonicas, whereas an engineering approach may focus more on efficiency and cost. Between the squeaks from the toy harmonicas and the noise from the servos entrusted to quiet them, the machine makes quite the mechanical racket. [Jonghong] indicates that the piece speaks to the interaction of machine (robot harmonica) and humanity (the finger which quells the noise).

It’s a tidily executed build which would be at home in any modern art gallery. It recalls memories of another such installation, which combines fans and lasers into a musical machine. Continue reading “The Battle Between Robot Harmonica And Machine Finger Rages On” →