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Category: “Bionic” prostheses

Becker Lock Grip Hand [Deutsch]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Becker Lock Grip Hand [Deutsch]; published October 20, 2009, 01:05; URL: https://www.swisswuff.ch/tech/?p=229.

BibTeX: @MISC{schweitzer_wolf_1571794851, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Becker Lock Grip Hand [Deutsch]}}, month = {October},year = {2009}, url = {https://www.swisswuff.ch/tech/?p=229}}


1 Comment

This article is also available in English.

Bisher hatte ich zwei Otto Bock Hooks (MovoHook 2Grip) und zwei Otto Bock Systemhände Typ 1-Zug (zieht man, geht sie auf, lässt man los, geht sie zu. Diese Art von Hand ist ganz nett und passt auch ganz gut zu den kosmetischen Handschuhen - aber wegen ihren adaptiven Greifmöglichkeiten machen neue myoelektrische Handprothesen einfach viel mehr Spass. Sie sind weder besonders gut verfügbar (Otto Bock Michelangelo, eventuell ab 2011; Touchbionics iLimb, Kostenpunkt etwa 78'000 CHF), noch besonders schnell, noch sind sie aufgrund ihrer Schafteigenschaften für mich derzeit überhaupt komfortable oder belastbar tragbar (siehe Vergleich). Aber so ein adaptiver Griff - das macht wirklich Spass.

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Becker Lock Grip hand [English]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Becker Lock Grip hand [English]; published October 19, 2009, 22:02; URL: https://www.swisswuff.ch/tech/?p=228.

BibTeX: @MISC{schweitzer_wolf_1571794851, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Becker Lock Grip hand [English]}}, month = {October},year = {2009}, url = {https://www.swisswuff.ch/tech/?p=228}}


Diesen Artikel gibts auch auf Deutsch.

My current setup so far only contained two Otto Bock System Hands - this model is a voluntary opening hand with a clamp mechanism. The Otto Bock hand is very nice and useful but obviously current myoelectric hands are more fun due to their adaptive grip options - far too expensive for that bit of electronics they contain, not too functional as they are slow to react, very cumbersome, and due to socket issues painful and not possible for me to wear right now - but far more fun. So I am in search for a good prosthetic terminal device.

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Creating a 2D textile cut pattern to match a specific 3D shape such as a prosthetic socket or hand

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Creating a 2D textile cut pattern to match a specific 3D shape such as a prosthetic socket or hand; published September 29, 2009, 11:44; URL: https://www.swisswuff.ch/tech/?p=224.

BibTeX: @MISC{schweitzer_wolf_1571794851, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Creating a 2D textile cut pattern to match a specific 3D shape such as a prosthetic socket or hand}}, month = {September},year = {2009}, url = {https://www.swisswuff.ch/tech/?p=224}}


If you have a prosthetic socket that requires a perfectly fitting sleeve, or a prosthetic hand that requires a perfectly fitting glove - or if you have some other 3D shape you need to convert into a suitable 2D textile cut pattern: here is how to create a sewing pattern from your specific 3D shapes.

I will look at textiles, textures and patterns separately. This only addresses how to cut 'em up.

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Artistic visions for prosthetic design X - mechanical bionic Becker Lock Grip Hand going Red Arm

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Wolf Schweitzer: Technical Below Elbow Amputee Issues - Artistic visions for prosthetic design X - mechanical bionic Becker Lock Grip Hand going Red Arm; published August 14, 2009, 13:54; URL: https://www.swisswuff.ch/tech/?p=218.

BibTeX: @MISC{schweitzer_wolf_1571794851, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Artistic visions for prosthetic design X - mechanical bionic Becker Lock Grip Hand going Red Arm}}, month = {August},year = {2009}, url = {https://www.swisswuff.ch/tech/?p=218}}


Original appearance

The Becker Lock Grip hand ([where to order, technical info]) ships with a sandpapered smooth but uncoated bass wood body. For my purposes that is just about the best thing that can ever happen to me - wood, a surface that can be carved, stained, painted, sprayed, covered with plastic shells or modified in any other way. It is the best possible material ever. Let me exaggerate - it is bone hard, feather light, dirt cheap and very beautiful. Plus, it's organic (any Californians reading this?). There is no better understanding of the condition that I am in.

So I wasn't going to let it stay like that....

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Tech bits III - prosthetic hands

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Wolf Schweitzer: Technical Below Elbow Amputee Issues - Tech bits III - prosthetic hands; published July 29, 2009, 22:56; URL: https://www.swisswuff.ch/tech/?p=211.

BibTeX: @MISC{schweitzer_wolf_1571794851, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Tech bits III - prosthetic hands}}, month = {July},year = {2009}, url = {https://www.swisswuff.ch/tech/?p=211}}


2 Comments

A look at an arbitrarily selected choice of prosthetic hands from close up. How realistic do they look?

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Body powered vs. myoelectric vs. cosmetic vs. none

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Wolf Schweitzer: Technical Below Elbow Amputee Issues - Body powered vs. myoelectric vs. cosmetic vs. none; published May 10, 2009, 21:17; URL: https://www.swisswuff.ch/tech/?p=173.

BibTeX: @MISC{schweitzer_wolf_1571794851, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Body powered vs. myoelectric vs. cosmetic vs. none}}, month = {May},year = {2009}, url = {https://www.swisswuff.ch/tech/?p=173}}


4 Comments

I now got a privately funded customized socket to try out a myoelectric prosthesis (used Otto Bock parts, initially functioning, no warranty). As my stump features some extra twitch packs (how do you call the muscle packs they put on your stump so you have a chance of creating extra myoelectric signals for modern prostheses?) I figured let us see how myoelectric stuff works as one day that may become interesting.

This adds to my collection in that I currently have a body powered setup (fully fledged), a cosmetic prosthesis (light weight, elegant) and the option of wearing none. Before opting for any bionic arm I was interested to see what issues might arise.

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RAPHaEL (Robotic Air Powered Hand with Elastic Ligaments)

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - RAPHaEL (Robotic Air Powered Hand with Elastic Ligaments); published May 10, 2009, 10:42; URL: https://www.swisswuff.ch/tech/?p=174.

BibTeX: @MISC{schweitzer_wolf_1571794851, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - RAPHaEL (Robotic Air Powered Hand with Elastic Ligaments)}}, month = {May},year = {2009}, url = {https://www.swisswuff.ch/tech/?p=174}}


3 Comments

If such hands can be mounted on long stumps - as there seems to be no requirement for a motor that may take up hand or wrist space - and if they can be gradually cable controlled (rather than through electrodes), these may offer very promising options. The thing is that myoelectric control may not only look slow, it also can be very uncomfortable to wear and only allow very limited function because of that. Despite that, a lot of funding, sales activity, general opinion making or media presence seems to be taken up by high-tech gadgets such as the DEKA arm, Otto Bock's Michelangelo hand or TouchBionics' iLimb whose demos can be matched with cable controlled arm demos and you will immediately understand - also from simple analysis of requirements - that a caring and responsible setup will improve an amputee's ability to work, act, and be well rather than addressing the needs of a prosthetic gadget builder -- two subjects that may, but do not necessarily have to, overlap.

From http://www.eng.vt.edu/news/article.php?niid=1686:

The Robotics and Mechanisms Laboratory (RoMeLa) of the College of Engineering at Virginia Tech has developed a unique robotic hand that can firmly hold objects as heavy as a can of food or as delicate as a raw egg, while dexterous enough to gesture for sign language.

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The Pentagon's Bionic DEKA Arm

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Wolf Schweitzer: Technical Below Elbow Amputee Issues - The Pentagon's Bionic DEKA Arm; published April 13, 2009, 07:39; URL: https://www.swisswuff.ch/tech/?p=167.

BibTeX: @MISC{schweitzer_wolf_1571794851, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - The Pentagon's Bionic DEKA Arm}}, month = {April},year = {2009}, url = {https://www.swisswuff.ch/tech/?p=167}}


4 Comments

While Otto Bock appeared to take part in the DEKA arm project with the Michelangelo hand, the DARPA is building a complex electronic arm as can be seen in a current CBS 60 Minutes broadcast.

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Reliability and speed of myoelectric prostheses

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Wolf Schweitzer: Technical Below Elbow Amputee Issues - Reliability and speed of myoelectric prostheses; published April 2, 2009, 17:25; URL: https://www.swisswuff.ch/tech/?p=153.

BibTeX: @MISC{schweitzer_wolf_1571794851, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Reliability and speed of myoelectric prostheses}}, month = {April},year = {2009}, url = {https://www.swisswuff.ch/tech/?p=153}}


5 Comments

I wonder about the reliability and speed of myoelectric prostheses - an issue that very much stays with us also with some new bionic arms such as the DEKA arm, the Michelangelo hand or the iLimb. Trigger for that question were a number of what could be termed possible urban myths. One guy gut stuck in  a bus holding on to a bar - and his prosthesis did not open any more. A nurse was giving a patient an urgently needed injection when shortly before the injection her prosthesis gave up. Other people apparently reported the prosthesis going haywire in proximity to electrical appliances. Furthermore, videos one can round up covering bionic and myoelectric prostheses seem to show a significant lag of action - a real pause, when a prosthesis is supposed to grab some object or perform otherwise. Most of the videos available for myoelectric prostheses seem to be considerably slower than - compared to a myoelectric prosthesis - my own experience with my body powered arm.

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Otto Bock Michelangelo hand

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Otto Bock Michelangelo hand; published March 27, 2009, 00:32; URL: https://www.swisswuff.ch/tech/?p=145.

BibTeX: @MISC{schweitzer_wolf_1571794851, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Otto Bock Michelangelo hand}}, month = {March},year = {2009}, url = {https://www.swisswuff.ch/tech/?p=145}}


5 Comments

[Find all articles about the Otto Bock Michelangelo hand]

While I am still busy lining up comparative benchmark type manipulations to compare iLimb and cable controlled prosthetics and considering artistic aspects of prosthetics, the new 2010 model of Otto Bock's Michelangelo hand apparently featuring 'biomimicry' (i.e., their version of the iLimb) can be seen already on video.

More recently seen, the OT Leipzig 2010 version looks disappointing in comparison. Probably we see the same phenomenon as in the car industry: gorgeous concept cars or advertising prosthesis - and no thrill afterwards.  I also attended a local live demo in May 2011 that seemed to subdue too exuberant initial expectations.

In trying to be 'bionic' (whatever the precise definition of that term may be), there are also other interesting projects such as the RAPHaEL hand or works done with Alejandro Hernandez Arieta at the AI Lab of the University of Zuerich. Related products seem to be the DEKA arm and the iLimb and the very similar looking BeBionic hand. Currently, research and development works towards multifinger and complex motion control rather than the two-electrode control that myoelectric hands have since the fifties.

The iLimb, BeBionic and Michelangelo hand:

  • are not at all thought-controlled (as awkward advertising hype may suggest)
  • look cool, but obviously any hand can be tweaked to also look cool
  • are restricted to myoelectric arms / sockets
  • only use two electrodes (open/close/switch) rather than currently emerging complex control paradigms
  • may deplete batteries rather quickly
  • are extremely/prohibitively expensive
  • offer limited grasp/lift options
  • seem to have significant delay (as other myoelectric arms)
  • emit irritating motor hissing sounds and are really noisy and loud
  • do not look good with cosmetic gloves on

Now, what immediately catches my eye in the Michelangelo hand videos is what appears to me to be a rather significant time lag between the moment a grip or hand movement seems to be in order and until it is actually done. I have started to investigate the subject of myoelectric prostheses and time lags a bit further even though maybe one day we will see mind control. It appears that these time lags are inherent to myoelectric control and so cable control wins.

Yes, of course - mind control! - "Only once I can use mind control, why the clumsy interface?" (Wolf Schweitzer, commenting on the Michelangelo hand, 2009)

As the Michelangelo hand is neither available, nor guaranteed to be affordable at all, nor is there any indication that it will work comfortably on a rather long stump such as mine given my problems I had so far using myoelectric technology I decided that a responsive and fast, sufficiently complex and cool hand does not necessarily have to be electric. Au contraire :-)

Meet my Becker Lock Grip Hand. It features an adaptive grip, particularly precise cable control, full manufacturer warranty and the option of getting a custom model made - also I went artistic with it and turned it into another Red Hand. It even solves difficult gripping problems that are probably way beyond these very modern gadgets. See my benchmark demos for handling eggs or picking grapes. This must be the ultimate proficiency test.

Copyright Otto Bock.

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Competitive prosthetic action - compare movement and function

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Competitive prosthetic action - compare movement and function; published September 21, 2008, 13:01; URL: https://www.swisswuff.ch/tech/?p=46.

BibTeX: @MISC{schweitzer_wolf_1571794851, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Competitive prosthetic action - compare movement and function}}, month = {September},year = {2008}, url = {https://www.swisswuff.ch/tech/?p=46}}


11 Comments

Current new developments in hand prosthetics are the iLimb (TouchBionics) and the Michelangelo hand (Otto Bock). Both are termed bionic hands. As these could be seen as very attractive, emotionally appealing and extremely expensive, they are a fascinating subject to examine.

This post also precedes some of my more refined attempts at defining, describing, specifying, evaluating and actually comparing prosthetic performance, such as a variation on the Carroll test.

One thing that amazes me is the obvious discrepancy between the feelings of the wearer (inside) and the feelings of the person watching the wearer (outside): when watching someone else wearing it from the outside, the iLimb - as I felt - looked artificial, stiff, slow, performed extremely loudly and to me appeared to be rather annoying, just as a car with a defective exhaust when seeing someone else wear it. Yet, operating it myself sucked me into a dream world of simulated hand function that I viewed entirely differently and it put a wide smile on my face. Seeing someone else smile at their own iLimb and witnessing the obvious discrepancy between its artificial appearance, slow and very restricted functionality and noisiness on one hand, and the smile it put on the wearer on the other hand, then completed a rather distressing experience to me.

It is ultimately the question why am I wearing a prosthesis? Is it merely a highly priced conversation piece, an item to wrap oral history around, a think to talk about such as the iLimb that is a the centerpiece of a large series of mostly social parading of the prosthetic object? Would I spend a staggering 78'000 CHF of my own money just to get someone tap my shoulder in a grocery store saying, "congratulations to your fine prosthesis, one can hardly see at all that it is an artificial limb"? See how much is that in dollars! I wear a prosthesis to show to others that I am willing to fake having a hand, I wear a prosthesis for sheer functionality. I'd wear one as fashion statement but for that, a self-funded 78'000 CHF hand necessarily must combine computing and programming options of a top-of-the-line workstation (huge one available for 15'000 CHF), the mechanical properties of a luxury class car (50'000 CHF), the stability and ease of handling of a Bosch drill hammer (1'000 CHF) *and* the battery or energy functionality as well as versatile electronics of a top-of-the-line laptop (available for 8'000 CHF). And we start off with a head start for good old mechanics here - the hook relaxes people as they see within a mile against the wind that I am missing a part, that there's a standard item to replace some of it, and it is also one reliable piece of hardware (even though we had to work on that both for the wrist and the hook).

The fluency and immediacy of available motion is an extremely important feature for my hook or mechanical hand. An experienced physiotherapist told me to go for a body powered prosthesis if only for that reasons - and stick with it for a couple of years. He said that only then will I grow into using it so much that I will really be able to rely on its advantages. The argument of fluency and immediacy becomes apparent when comparing the iLimb in its respective appearances on YouTube, and my hook in the following videos. And recently I realized that one cannot thoroughly get accustomed to such a prosthetic setup without letting it grow on oneself, without allowing oneself to naturally incorporate its function into one's life.

In response to TouchBionics "get a grip on functionality" demo videos http://www.touchbionics.com/professionals.php?pageid=44&section=5 I recorded similar activities using the Otto Bock MovoHook 2Grip for 1:1 comparison. My evaluation  bases on my current personal requirements as a right below elbow amputee.

Recently, detailed accounts of iLimb usage by Darin Sargent (see: theadventuresoftheilimb.wordpress.com) highlight activities such as reading a newspaper or working having it on in the kitchen. As I see it, Darin Sargent really and ultimately tells us throughout his extensive online video collection that basically he was real lucky to get insurance to pay for the iLimb (he did not pay 78'000 CHF) but it appears as if the product was never formally evaluated by his insurance for function or performance.

As his website articles imply, he uses it more as a social prop than as a functional replacement. And we learn that his insurance paid for it. That is like learning that they just finished a gold toilet for the king. Maybe that is nice for the king - but I really see no further conclusion to be made. His website implies that Darin has no idea how to conduct a technical evaluation and he even uses words that indicate that he looks down on people that go down into the pits and actually have to rely on their prostheses for work. If he despises manual labor and the big problems that come with evaluating prostheses for that purpose he has every right to say so. If he looks down on people that wear hooks for performance and hands for appearance I don't care - maybe that's what he has to do.

So the overall impression I get is that yet another high ranking army officer / priest / motivational speaker / retired person walking around with a hugely expensive dummy hand prop is not a very good ambassador for prosthetic manual dexterity. Just to bring that question to the point.

Price definitely plays a role in prosthetics. So it is relevant to note that my current setup (Otto Bock parts, two MovoHook 2Grip 10A80 hooks, one System hand voluntary opening, cable controlled socket with rapid swap mechanism, all parts pimped for optimal performance) costs a mere fraction of a prosthesis featuring the iLimb by TouchBionics.

Comparison of the prices for terminal devices (iLimb hand wiothout prosthetics: around 50'000 CHF (not covered by insurance); Otto Bock system hand: about 800 CHF; Otto Bock hook: about 1'200 CHF - prosthetic arm with iLimb hand: around 78'000 CHF, prosthetic arm using body powered technology: around 6'000 CHF) shows that we are dealing with extreme differences in prosthetic cost.

Now, I like to be able to smoothly and without much technological overhead work through technical situations by wearing a contextually intelligent solution on my arm stump.That does not mean that I only and exclusively wear a hook? No!

  • I like the constant and reliable availability of function (without recharging or additional weight) of the hook. Using it for cutting, grinding, working with aggressive solvents, the hook as many times proven technical advantage over any other replacement as all it takes is a scrub, disinfectant, ultrasound cleaning and we are back on track. At intervals, I get the silicon covers replaced but these are really cheap parts.
  • I like to wear the Otto Bock system hand for certain situations and have that reliable too. And very good looking.
  • Currently I am working on an art project as well.

As TouchBionics advertise the possibility to actually conduct a number of manipulations using their iLimb I found it relevant to offer a 1:1 comparison to this type of functionality. It may help to identify areas of improvement, it may help to adjust unrealistic expectations, and it may help to illustrate functionality. Images or pictures, videos or short films just provide a better illustration than mere words saying 'been there, done that'. - And then, most of these are situations that are just a bit harder to do with the amputation stump alone, they may take more time without prosthesis, or risk getting the stump injured.

Taking off wrist watch

I can remove my wrist watch using the stump or the hook but also using the Otto Bock Voluntary Opening System Hand. I am now wearing a Regal Prosthetics silicon glove that features great appearance and sturdy finger tips. Key to getting a wrist watch off fast is finding out how to best twiddle the lock. Here, I slide the plastic band through the lock and then pull a bit to get the lock pin out of the hole. Then I use an oblique pull trick for the wrist band to flip the pin over to the other side so it does not lock again (video: 0:10 to 0:15 seconds). All in all I get the wrist watch off in just under 20 seconds and that is in slow demo mode and with a mechanical prosthetic hand. Always remember: if you are after realistic looks, go for a good silicone glove (regardless of what you wear underneath); if you are after smooth, silent and immediate action, get cable control (regardless of the terminal device); if you need precise and full force grip or push/pull action, get a hook and if you want to look anthropomorphic get a mechanical hand.

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