Assistive Gloves Come In Pairs

August 24, 2020 by Brian McEvoy 11 Comments

We have to hand it to this team, their entry for the 2020 Hackaday Prize is a classic pincer maneuver. A team from [The University of Auckland] in New Zealand and [New Dexterity] is designing a couple of gloves for both rehabilitation and human augmentation. One style is a human-powered prosthetic for someone who has lost mobility in their hand. The other form uses soft robotics and Bluetooth control to move the thumb, fingers, and an extra thumb (!).

The human-powered exoskeleton places the user’s hand inside a cabled glove. When they are in place, they arch their shoulders and tighten an artificial tendon across their back, which pulls their hand close. To pull the fingers evenly, there is a differential box which ensures pressure goes where it is needed, naturally. Once they’ve gripped firmly, the cables stay locked, and they can relax their shoulders. Another big stretch and the cords relax.

In the soft-robotic model, a glove is covered in inflatable bladders. One set spreads the fingers, a vital physical therapy movement. Another bladder acts as a second thumb for keeping objects centered in the palm. A cable system draws the fingers closed like the previous glove, but to lock them they evacuate air from the bladders, so jamming layers retain their shape, like food in a vacuum bag.

We are excited to see what other handy inventions appear in this year’s Hackaday Prize, like the thumbMouse, or how about more assistive tech that uses hoverboards to help move people?

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Hand Depanelizer Gets Pneumatic Upgrade

July 21, 2020 by Tom Nardi 14 Comments

In high volume production, smaller PCBs are often “panelized” so that multiple copies can be shuffled through assembly as a single piece. Each board is attached to the panel with a few strategically placed tabs, not unlike the sprues in a plastic model kit. If you only have to separate a few boards you can simply cut them with a hand nipper, but when you’re doing hundreds or thousands of boards, it quickly becomes impractical.

Which is where [Clough42] found himself recently. Looking to improve the situation without breaking the bank, he decided to automate his trusty hand-held depanelizer tool. The basic idea was to build an actuator that could stand in for his own hand when operating the tool. He already had a pneumatic cylinder that he could power the device with, he just needed to design it.

In the video below, he walks the viewer though his CAD design process for this project. His first step, which is one that’s often overlooked by new players, is creating digital representations of the hardware he’s using. This allows him to quickly design 3D printed parts that have the proper dimensions and clearances to interface with his real-world components. Remember: it’s a lot easier to adapt your 3D model to the components on hand than the other way around.

With the appropriate valves, hoses, and a foot pedal attached to the pneumatic cylinder, he’s able to operate the cutter completely hands-free. He still has to manually move the panel around, but at least it saves him from the repetitive squeezing motion.

With a tool like this and a custom testing jig, you’ll be producing PCBs like the pros in no time.

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Pneumatic Glove For Therapy And Experimentation

February 12, 2020 by Lewin Day 3 Comments

Many projects have aimed to replicate the function of the human hand, creating robotic structures that mimic real anatomy. Fewer have attempted to work with human hands directly. SoftGlove is a project by [france.bonde] that uses pneumatics to do just that.

The glove works by using a silicone pneumatic actuator for each digit on the human hand, attached to a glove. These are created with 3D printed molds, into which EcoFlex silicone is poured. A FlowIO device is used to run the pneumatics, which combines a microcontroller with penumatic hardware to pump air in and out of the actuators.

The goal of the project is to use a companion unit, in which a glove with flex sensors is used to make the SoftGlove mimic its movements. This would allow SoftGlove to move the fingers of a person with damaged muscle control, potentially aiding the muscles and nerves to recover when used in a therapeutic setting.

It’s exciting to see typical maker technologies used in a context to create better outcomes for patients, and we’re excited to see where this project leads next. It also has potential applications for robotic actuators, too. Programmable Air is another exciting project working in this space, too. And of course, if you’ve got a hot pneumatics project you’re cooking up in the garage, be sure to let us know!

Stacks Of Spring Washers Power The Drawbar On This CNC Mill Conversion

January 11, 2020 by Dan Maloney 25 Comments

With Tormach and Haas capturing a lot of the entry-level professional market for CNC machines, we don’t see too many CNC conversions of manual mills anymore. And so this power drawbar conversion for a Precision Matthews mill really caught our eye.

What’s that, you say? Didn’t [Physics Anonymous] already build a power drawbar for a mill? They did, and it was quite successful. But that was based on a pneumatic impact wrench, and while it worked fine on a manual mill, the same approach would be a bit slow and cumbersome on a CNC mill. For this build, they chose a completely different approach to providing the necessary upward force to draw the collet into the collet holder and clamp down on the tool: springs. Specifically, Belleville spring washers, which are shaped like shallow cups and can exert tremendous axial force over a very short distance.

[PA] calculated that they’d need to exert 2,700 pounds (12,000 Newtons) of force over a length of a couple of inches, which seems outside the Belleville washer’s specs. Luckily, the springs can be stacked, either nested together in “series” to increase the load force, or alternating in “parallel” to apply the rated force over a greater distance. To compress their stack, they used a nifty multi-stage pneumatic cylinder to squash down the springs and release the collet. They also had to come up with a mechanism to engage to machine’s spindle only when a tool change is called for. The video below details the design and shows the build; skip to 11:32 to see the drawbar in action.

We’re looking forward to the rest of [Physics Anonymous]’ conversion. They’re no strangers to modifying off-the-shelf machines to do their bidding, after all – witness their improvements to an SLA printer.

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Soft Rotating Pneumatic Actuators

December 12, 2018 by Lewin Day 11 Comments

When we think of pneumatic actuators, we typically consider the standard varieties of pneumatic cylinder, capable of linear motion. These can be referred to as “hard” actuators, made of rigid components and capable of great accuracy and force delivery. However, “soft” actuators have their own complementary abilities – such as being able to handle more delicate tasks and being less likely to injure human operators when used in collaborative operations. The Whitesides Research Group at Harvard University has undertaken significant research in this field, and released a paper covering a novel type of soft pneumatic actuator.

The actuator consists of a series of soft, flexible sealed chambers which surround a wooden dowel in the center. By applying vacuum to these various chambers, the dowel in the center can be pulled into up to eight different positions. It’s a unique concept, and one we can imagine could have applications in various material processing scenarios.

The actuator was built by moulding elastomers around 3D printed components, so this is a build that could theoretically be tackled by the DIYer. The paper goes into great detail to quantify the performance of the actuator, and workshops several potential applications. Testing is done on a fluid delivery and stirring system, and a tethered robotic walker was built. The team uses the term cVAMS – cyclical vacuum actuated machine – to describe the actuator technology.

The world of soft robotics is a hot bed of development, and we look forward to further work in this field. It’s not just Harvard, either – we’ve seen interesting work from Yale and from the Hackaday community too!

Soft Silicone Pneumatics Are 3D-printed In A Tub Of Gel

November 27, 2018 by Brian Boucheron 28 Comments

We’ve seen our fair share of soft silicone robots around here. Typically they are produced through a casting process, where molds are printed and then filled with liquid silicone to form the robot parts. These parts are subsequently removed from the molds and made to wiggle, grip, and swim through the use of pneumatic or hydraulic pumps and valves. MIT’s Self-Assembly Lab has found a way to print the parts directly instead, by extruding silicone, layer by layer, into a gel-filled tank.

The Self-Assembly Lab’s site is unfortunately light on details, but there is a related academic paper (behind a paywall, alas) that documents the process. From the abstract, it seems the printing process is intended for more general purpose printing needs, and is able to print any “photo or chemically cured” material, including two-part mixtures. Additionally, because of the gel-filled tank, the material need not be deposited in flat layers like a traditional 3D-printer. More interesting shapes and material properties could be created by using the full 3d-volume to do 3D extrusion paths.

To see some of the creative shapes and mechanisms developed by MIT using this process, check out the two aesthetically pleasing videos of pulsating soft white silicone shapes after the break.

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Air Wrench Becomes A Milling Machine Power Drawbar

September 3, 2018 by Dan Maloney 20 Comments

We sometimes wonder if designers ever actually use their own products, or even put them through some sort of human-factors testing before putting them on the market. Consider the mechanism that secures toolholders to the spindle of a milling machine: the drawbar. Some mills require you to lock the spindle with a spanner wrench, loosen the drawbar with another wrench, and catch the released collet and tool with – what exactly?

Unwilling to have the surgical modifications that would qualify him for the Galactic Presidency, [Physics Anonymous] chose instead to modify his mill with a power drawbar. The parts are cheap and easily available, with the power coming from a small butterfly-style pneumatic wrench. The drawbar on his mill has a nearly 3/8″ square drive – we’d guess it’s really 10 mm – which almost matches up with the 3/8″ drive on the air wrench, so he whipped up a female-to-female adapter from a couple of socket adapters. The wrench mounts to a cover above the drawbar in a 3D-printed holster. Pay close attention to the video below where he goes through the Fusion 360 design; we were intrigued by the way he imported three orthogonal photos on the wrench to design the holster around. That’s a tip to file away for a rainy day.

This is a great modification to a low-cost milling machine. If you’re in the process of buying machine tools, you should really check out our handy buyer’s guides for both milling machines and lathes. It’ll let you know what features to look out for, and which you’ll have to add later.

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