One of the great successes of desktop 3D printers is custom prosthetics and orthotics. For a fraction of the price of a prosthetic arm, you can buy a machine capable of producing hundreds of completely customizable prosthetics. [Taran Ravindran]’s project in the running for the 2017 Hackaday Prize follows the long tradition of building customized prosthetics. His prosthetic hand designed to be simpler and cheaper than conventional artificial limbs while still giving us some innovation in how this hand will move.
The digits on [Taran]’s hand are controlled by linear servos pulling on a series of Bowden cables. One servo actuates the index finger, with a double differential to close the three less important figures — the middle, ring, and pinky fingers don’t need the articulation of the forefinger and thumb. Those three are actuated together, saving cost and complexity — they basically operate to support the index and thumb rather than being controllable independently. The thumb has 2 DOF by itself to give it the maximum amount of utility.
Another area of importance [Taran]’s focusing on is the matter of ease of use. If the prosthesis is too complicated, difficult, or unpleasant to use, it won’t get used regardless of its awesome features. Knowing this, he focused on making the hand as simplified as possible. Right now, the project has been modeled in CAD, and [Taran] is just waiting for the SLS parts to arrive before assembling the whole thing. It’s a great project, and a great entry for this year’s Hackaday Prize.
When it comes to high-tech bionic legs for amputees, all the cool stuff is titanium, carbon fiber or other, more exotic materials. With carbon fiber “blades” all the rage, it’s easy to forget that simpler technologies still work, and could be made to work even better with the addition of some inexpensive electronics. The Economical Bionic Leg project is the result of that idea.
Project creators [PremJ20] and [G.Vignesh] aren’t kidding about bringing the cost of these bionic legs down. The target goal is $60 per, with stainless steel and silicon rubber as a cheaper alternative to carbon fiber — the rubber would be molded to fit the amputated region. The heart of the project is a Particle Photon development board, with a flex sensor and accelerometer monitoring the prosthesis and supplying data to the cloud. It’s essentially a basic prosthetic leg with a monitoring system built in. Placing a sensor cuff on the regular leg, the artificial limb’s flexibility can be fine-tuned to match the two.
Will this inexpensive bionic leg ever compete in the Olympics, like [Oscar Pistorious] run in the 2012 London event? Probably not — the tech that goes into artificial limbs has the same amount of material science going into it as F1 racing and turbojet design. Still, this is a very cheap way to bring tech into something that desperately needs to be cheaper, and it’s a great Hackaday Prize entry, to boot.
Is this a case of a good design gone wrong in the build phase? Or is this DIY prosthetic arm a poor design from the get-go? Either way, [Will Donaldson] needs some feedback, and Hackaday is just the right place for that.
Up front, we’ll say kudos to [Will] for having the guts to post a build that’s less than successful. And we’ll stipulate that when it comes to fully articulated prosthetic hands, it’s easy to fail. His design is ambitious, with an opposable thumb, fingers with three phalanges each, a ball and socket wrist, and internal servos driving everything. It’s also aesthetically pleasing, with a little bit of an I, Robot meets Stormtrooper look.
But [Will]’s build was plagued with print problems from the start, possibly due to the complex nature of the bosses and guides within the palm for all the finger servos. Bad prints led to creaky joints and broken servos. The servos themselves were a source of consternation, modified as they were for continuous rotation and broken apart for remotely mounting their pots in the hand’s knuckles. The video below relates the tale of woe.
There’s a lot to admire with [Will]’s build, but it certainly still has its issues. He’s almost to the point of other more successful DIY hand builds but just needs a little help. What say you in the comments line? Continue reading “Fail of the Week: Good Prosthetic Hand Design Goes Bad”
At least one in their lives — or several times a day — everyone has wished they had a third hand to help them with a given task. Adding a mechanical extra arm to one’s outfit is a big step, so it might make sense to smart small, and first add an extra thumb to your hand.
This is not a prosthetic in the traditional sense, but a wearable human augmentation envisioned by [Dani Clode], a master’s student at London’s Royal College of Art. The thumb is 3D-printed out of Ninjaflex and mounted to a printed brace which slides over the hand. One servo rotates the thumb, and a second pulls it closed using a bowden cable system — not unlike that of a bicycle brake. Control of the thumb is achieved by pressure sensors in the wearer’s shoes, linked via Bluetooth to a wristband hosting the servos and the electronics. We already use our hands and feet in conjunction, so why not capitalize on this intuitive link?
Continue reading “Three Thumbs, Way, Way Up!”
Hands can grab things, build things, communicate, and we control them intuitively with nothing more than a thought. To those who miss a hand, a prosthesis can be a life-changing tool for carrying out daily tasks. We are delighted to see that [Alvaro Villoslada] joined the Hackaday Prize with his contribution to advanced prosthesis technology: Dextra, the open-source myoelectric hand prosthesis.
Dextra is an advanced robotic hand, with 4 independently actuated fingers and a thumb with an additional degree of freedom. Because Dextra is designed as a self-contained unit, all actuators had to be embedded into the hand. [Alvaro] achieved the necessary level of miniaturization with five tiny winches, driven by micro gear motors. Each of them pulls a tendon that actuates the corresponding finger. Magnetic encoders on the motor shafts provide position feedback to a Teensy 3.1, which orchestrates all the fingers. The rotational axis of the thumb is actuated by a small RC servo.
In addition to the robotic hand, [Alvaro] is developing his own electromyographic (EMG) interface, the Mumai, which allows a user to control a robotic prosthesis through tiny muscle contractions in the residual limb. Just like Dextra, Mumai is open-source. It consists of a pair of skin electrodes and an acquisition board. The electrodes are attached to the muscle, and the acquisition board translates the electrical activity of the muscle into an analog voltage. This raw EMG signal is then sampled and analyzed by a microcontroller, such as the ESP8266. The microcontroller then determines the intent of the user based on pattern recognition. Eventually this control data is used to control a robotic prosthesis, such as the Dextra. The current progress of both projects is impressive. You can check out a video of Dextra below.
Continue reading “Hackaday Prize Entry: Open-Source Myoelectric Hand Prosthesis”
You heard right. There’s a team of scientists in Europe who are arranging the world’s first Cyborg Olympics, called the Cybathlon. Hosted in Zurich this October, it aims to help gauge the performance and advancement in the latest developments of prosthesis and other devices that can augment human ability beyond what is considered normal or baseline.
The best example of this is [Oscar Pistorius] — the man with fiberglass spring legs. He’s a double amputee who can run at an Olympic level — or maybe even faster. With the Cybathlon, his prosthesis would not only be accepted, but encouraged to help demonstrate and further the technology by adding a competitive angle to the companies manufacturing them. Continue reading “Cyborg Olympics is Coming this Fall”
For the last few years now, the 3D printing community has been searching for a groundbreaking application for out little boxes of plastic squirting goodness. On of the most interesting applications the community has stumbled upon is prosthetics.
There have been a lot of people warming up their 3D printers and laser cutters to make prosthetic limbs in recent years. For [OpenBionics]’ entry for The Hackaday Prize, they’re building a prosthetic hand that costs less than $200, weighs less than 300 grams, and can be easily fabricated with 3D printers and laser cutters.
The human hand is the most complex end-effector on the planet, and emulating its range of motion is a difficult task. Still, the [OpenBionics] team is working hard to properly emulate a thumb with three degrees of freedom, putting 144 different grasps on the hand, and making their hand useful with soft fingertips.
Even with all this capability, [OpenBionic]’s robotic hand – motors and all – is about the same size as a normal human hand. That’s incredible, especially when you consider the motors for your hand – muscles – are all in your arm.
The team has put together a video demoing the capabilities of their hand. It’s somewhat remarkable, and able to do everything from lift a coffee cup to holding a pen. You can check that video out below.
Continue reading “Hackaday Prize Entry: OpenBionics”