Meticulous Bionic Hand

[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 asĀ aluminum finger replacements, but this is a whole hand with fantastic range and fidelity.

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Roller-Based Robot Hand Grasps

In a recent International Conference on Robotics and Automation paper, [Shenli Yaun] and some others from Stanford discuss the design of a roller-based robot hand that has many features that mimic the human hand. The key feature is that each of the three fingers has a roller with a small geared motor.

The rollers allowed the hand to change an object’s orientation without losing its grasp. Of course, this works well with spherical objects like a ball. But the video shows that it can manipulate other items like a 6-sided die, a water bottle, or even a piece of paper. By spreading the fingers it can even hold large objects you wouldn’t expect at first glance.

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Assistive Gloves Come In Pairs

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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Rolling Out A New Robot Arm

A lot of great scientific breakthroughs come through imitating nature, but technology often runs up against limits in certain areas. This is particularly evident in robotics, where it takes a lot of effort (and cost) to build a robot which can effectively manipulate heavy objects but not crush others which are more delicate. For that, a research group has looked outside of nature, developing a robotic grasper which uses omnidirectional wheels to grab various objects.

The robot hand is composed of three articulating fingers with fingertips which are able to actively manipulate the object that the hand is holding. With static fingertips, it is difficult to manipulate an object in the hand itself, but with the active surfaces at the fingertips it becomes easier to rotate the object without setting it down first or dropping it.

The project is much more than designing the robot hand itself, too. The robot uses calculated kinematics to manipulate the objects as well, but a second mode was also tried where the robot was able to “learn” how to handle the object it was given. The video linked below shows both modes in operation, with interesting results. If you prefer more biologically-inspired robot arms, though, there are always novel designs based on non-humans.

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Haptic Glove Controls Robot Hand Wirelessly

[Miller] wanted to practice a bit with some wireless modules and wound up creating a robotic hand he could teleoperate with the help of a haptic glove. It lookes highly reproducible, as you can see the video, below the break.

The glove uses an Arduino’s analog to digital converter to read some flex sensors. Commercial flex sensors are pretty expensive, so he experimented with some homemade sensors. The ones with tin foil and graphite didn’t work well, but using some bent can metal worked better despite not having good resolution.

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This Machine Teaches Sign Language

Sign language can like any language be difficult to learn if you’re not immersed in it, or at least learning from someone who is fluent. It’s not easy to know when you’re making minor mistakes or missing nuances. It’s a medium with its own unique issues when learning, so if you want to learn and don’t have access to someone who knows the language you might want to reach for the next best thing: a machine that can teach you.

This project comes from three of [Bruce Land]’s senior electrical and computer engineering students, [Alicia], [Raul], and [Kerry], as part of their final design class at Cornell University. Someone who wishes to learn the sign language alphabet slips on a glove outfitted with position sensors for each finger. A computer inside the device shows each letter’s proper sign on a screen, and then checks the sensors from the glove to ensure that the hand is in the proper position. Two letters include making a gesture as well, and the device is able to track this by use of a gyroscope and compass to ensure that the letter has been properly signed. It appears to only cover the alphabet and not a wider vocabulary, but as a proof of concept it is very effective.

The students show that it is entirely possible to learn the alphabet reliably using the machine as a teaching tool. This type of technology could be useful for other applications as well, such as gesture recognition for a human interface device. If you want to see more of these interesting and well-referenced senior design builds we’ve featured quite a few, from polygraph machines to a sonar system for a bicycle.

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Dexterity Hand Is A Configurable Prosthetic Hand

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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