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Case-study of a user-driven prosthetic arm design: bionic hand versus customized body-powered technology in a highly demanding work environment [article out]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Case-study of a user-driven prosthetic arm design: bionic hand versus customized body-powered technology in a highly demanding work environment [article out]; published January 4, 2018, 14:29; URL: https://www.swisswuff.ch/tech/?p=8066.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Case-study of a user-driven prosthetic arm design: bionic hand versus customized body-powered technology in a highly demanding work environment [article out]}}, month = {January},year = {2018}, url = {https://www.swisswuff.ch/tech/?p=8066}}


 


This is a blog post of one of the rare focused and well based scientific journal articles that really explains how real work, body powered and myoelectric arms relate and go together for a unilateral right below elbow amputee in a physically demanding work environment.

The prior presentation of this paper [poster at Cybathlon symposium 2016], which had been more pragmatically worded (with me thinking people would know anyway), this was now written up as article and published. During that process, the reviewers clearly made great points of all kinds of aspects I never knew were not sky clear to everyone.

So maybe, writing a ~ 30 page case study with > 210 references does clarify stuff, at least potentially and for those that actually read it. But possibly, it still requires attention to even just read it.

Knowledge does not come easy, Highlander! (Nakano, in: Highlander III The Final Dimension)

 

If you are more interested in visionary posts, read about the gadget features of the prosthetic arm in Kingsmen: The Golden Circle [link]. And technically, myoelectric control did have it coming. That technology remained uncool for four decades [link].

Publication [link]

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How robot technology that is advertised with technically insufficient propaganda numbers does make us truly angry [movie reference: HBO miniseries "Chernobyl"]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - How robot technology that is advertised with technically insufficient propaganda numbers does make us truly angry [movie reference: HBO miniseries "Chernobyl"]; published June 21, 2019, 18:12; URL: https://www.swisswuff.ch/tech/?p=9711.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - How robot technology that is advertised with technically insufficient propaganda numbers does make us truly angry [movie reference: HBO miniseries "Chernobyl"]}}, month = {June},year = {2019}, url = {https://www.swisswuff.ch/tech/?p=9711}}


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Sometimes, even a fictionalized docu-drama hits all the right notes.

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How is "John without arms" an ableist derogatory Brazilian / Portuguese idiom that directly attributes ignorance and laziness to disability and then uses it a technical amputation descriptor to denote the lazy or ignorant?

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - How is "John without arms" an ableist derogatory Brazilian / Portuguese idiom that directly attributes ignorance and laziness to disability and then uses it a technical amputation descriptor to denote the lazy or ignorant?; published June 20, 2019, 05:33; URL: https://www.swisswuff.ch/tech/?p=9683.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - How is "John without arms" an ableist derogatory Brazilian / Portuguese idiom that directly attributes ignorance and laziness to disability and then uses it a technical amputation descriptor to denote the lazy or ignorant?}}, month = {June},year = {2019}, url = {https://www.swisswuff.ch/tech/?p=9683}}


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João sem braço ("armless John") is a Brazilian or Portuguese idiom that is used as an epithet for an ignorant and lazy person.

As that in itself is hardly a positive attribute, it is relevant to understand the position of amputees in society, their individual and collective role, in order to see how this is a very ableist and thus derogatory way to formulate the attribute of ignorant or lazy.

Can you open the zipper of my pants please? - Why, do you need to go to the bathroom? - No... (from [link])
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Becker Hand - best grip in town [mechanism visualization]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Becker Hand - best grip in town [mechanism visualization]; published April 19, 2019, 11:57; URL: https://www.swisswuff.ch/tech/?p=9609.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Becker Hand - best grip in town [mechanism visualization]}}, month = {April},year = {2019}, url = {https://www.swisswuff.ch/tech/?p=9609}}


Visualisation of the mechanism or inner workings of one of the fastest "bionic" (i.e. it has an adaptive grip) prosthetic hands has so far been relatively elusive.

The mechanism is one of the most extremely evolved in prosthetic hand device history - the manufacturer overlooks around 70 years of continuous product evolution. As many large manufacturers today do not "listen" and are not open for suggestion or critical evaluation, they are not making most of their shorter time of product evolution, further crippling their already short market exposure. This explains why the Becker hand is one astonishing perfect product - highly functional, attractive, very robust and very affordable.

Now, we worked out how to plastically show the inner workings or mechanism of a Becker Imperial hand.

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Zweimaltot - Beat Glogger (Buchbesprechung)

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Zweimaltot - Beat Glogger (Buchbesprechung); published April 9, 2019, 13:14; URL: https://www.swisswuff.ch/tech/?p=9492.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Zweimaltot - Beat Glogger (Buchbesprechung)}}, month = {April},year = {2019}, url = {https://www.swisswuff.ch/tech/?p=9492}}


Ich habe mir nun termingerecht das Buch "Zweimaltot" von Beat Glogger vorgenommen. Meine Buchbesprechung, Review oder Rezension hier verrät allerdings Einzelheiten über den Ausgang (Spoiler Alert).


(C) Copyright Reinhardt Verlag

Das Buch gibt es hier:

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Soldering cable connection and heat shrinking tube over connection (Extreme Cyborging Microworks)

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Soldering cable connection and heat shrinking tube over connection (Extreme Cyborging Microworks); published April 4, 2019, 06:59; URL: https://www.swisswuff.ch/tech/?p=9463.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Soldering cable connection and heat shrinking tube over connection (Extreme Cyborging Microworks)}}, month = {April},year = {2019}, url = {https://www.swisswuff.ch/tech/?p=9463}}


A full understanding what amputees do or do not in their real life has so far escaped the acumen of research and development. This explains how > 85% of us still run free, without the real restriction of having to pay massive money for technology that basically makes life more difficult.

A notable exception is my body powered split hook. As we can show how academics comprehensively fail to grasp (haha) the scope and use of prosthetic arm use, even a modest achievement such as this appears quite noteworthy and definitely reportable. After all, absolutely no (0) achievement was delivered by any R&D in the domain of myoelectric arms to this day that has made it to actual everyday use and hard work delivery, both since Cybathlon 2016 (that promised it would "push" development) and generally since >40 years of "research" into myoelectric arm control. As they all have more than a lot to learn (not advancing problematically high error rates in >40 years is a catastrophe or wouldn't you say), we are called upon to focus on the basic.

Today, how to attach the cable of a power supply to a pump.

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Prosthetic split-hooks are by far the MORE MODERN concept than prosthetic hands and they did not take long to get vilified [what you all got wrong about history]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Prosthetic split-hooks are by far the MORE MODERN concept than prosthetic hands and they did not take long to get vilified [what you all got wrong about history]; published March 3, 2019, 23:01; URL: https://www.swisswuff.ch/tech/?p=9423.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Prosthetic split-hooks are by far the MORE MODERN concept than prosthetic hands and they did not take long to get vilified [what you all got wrong about history]}}, month = {March},year = {2019}, url = {https://www.swisswuff.ch/tech/?p=9423}}


We are told by prosthetic R&D aficionados, by film makers, fiction authors, popular culture and whatnot, that a prosthetic hook (i.e., split-hook) is "old", and a prosthetic hand is "new". Also, we get told that myoelectric arms are very modern in terms of control technology, whereas some recent media and prosthetic manufacturers even called myoelectric control "brain control".

None of that is true, quite obviously, while we realize that reality is rather different. Rather strikingly different, in fact.

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Was ist mit Cybathlon@SCHOOL moeglicherweise problematisch?

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Was ist mit Cybathlon@SCHOOL moeglicherweise problematisch?; published March 2, 2019, 11:39; URL: https://www.swisswuff.ch/tech/?p=9404.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Was ist mit Cybathlon@SCHOOL moeglicherweise problematisch?}}, month = {March},year = {2019}, url = {https://www.swisswuff.ch/tech/?p=9404}}


Cybathlon@SCHOOL ist ein Programm, das Behinderte, Armamputierte auch, als "Material" bezeichnet und anpreist.

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Angular constraints of prosthetic grippers and functional success correlation [technical evaluation]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Angular constraints of prosthetic grippers and functional success correlation [technical evaluation]; published February 11, 2019, 04:55; URL: https://www.swisswuff.ch/tech/?p=9322.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Angular constraints of prosthetic grippers and functional success correlation [technical evaluation]}}, month = {February},year = {2019}, url = {https://www.swisswuff.ch/tech/?p=9322}}


I had evaluated, subjectively, the grip performance of various prosthetic options that I have. These have been already analysed in the context of grip taxonomy, where so far, research has largely focused on grip geometry as such, using some idiosyncratic logic that I found not too relevant.

Using a more relevant logic, I approached the question of grip mechanic from a different angle, both verbally and proverbially speaking: from a user angle, both actually geometrically and subjectively speaking.

I realized that most of my frequently used grips and grip situations fall into a far more narrow range of angle distributions than I had ever assumed.  So I sat down to add "typical object angles" to my already present grip success statistics over a list of my most frequently or typically used grips. Then I did that in theory and THEN I figured, why not go and video some. Thereby, a prosthetic hook as gripper device appears to be a lot more advanced, design wise, geometrically, in reducing device materials, bulk and design to approximate a really good overall use performance than the iLimb (which I have here also for as much testing as I like) and with that, many current commercial (or other) multi articulated hands.

In fact, prosthetic hands appear to be by far the older (and thus possibly less reflected) geometric design idea of a prosthetic arm's terminal device than the definitely more modern split hook. I may also go history hunting, but the claim that a split hook is old or outdated, and that therefore by inference a prosthetic hand is automatically new or more modern, as an idea, is wrong, particularly technically speaking. But also historically, to replace a hand with a hand is a straightforward design idea, that does not take any imagination, thus it is reportedly old, very old.

The far more elegant reduction, also of angles and controls, to fit into the limited action and option constraints of an arm amputee, is certainly that of a body powered split hook. It boils down the prosthetic needs to a successful sleek elegant reduction of a functional minimum, making it the ideal choice for anyone that wants a maximum of performance from a minimum of failure, cost, decay, bulk, futile grip attempts and total overhead. The subtle distinction is that a "body powered split hook" is an entirely different beast than a passive hook, obviously, which probably no one ever noticed, particularly not the people that assumed that a body powered split hook is best portrayed by installing a "Captain Hook" metaphor.

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Myoelectric prosthetic arms do not "really" function - so whom to sell them to? [cynical economic considerations]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Myoelectric prosthetic arms do not "really" function - so whom to sell them to? [cynical economic considerations]; published February 2, 2019, 15:11; URL: https://www.swisswuff.ch/tech/?p=9304.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Myoelectric prosthetic arms do not "really" function - so whom to sell them to? [cynical economic considerations]}}, month = {February},year = {2019}, url = {https://www.swisswuff.ch/tech/?p=9304}}


Myoelectric prosthetic arms do not "really" work, we all know that, and it has been clear for decades.These factual aspects are difficult to make that problem go away like, poof. With that the more interesting question is: whom do we sell these to?

While selling to people that are gullible [link] seems to have a lot going for it, it is risky. A more sustained approach may base on taking actual risk factors for myoelectric failure into account:

  • Sweat
  • Weight
  • General error rate

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Academically published myoelectric arm control error rates since ~1980 remain extremely high, far above any real life use requirement, and not even a slight trend to more reliable control in sight: what does this mean?

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Academically published myoelectric arm control error rates since ~1980 remain extremely high, far above any real life use requirement, and not even a slight trend to more reliable control in sight: what does this mean?; published January 29, 2019, 19:00; URL: https://www.swisswuff.ch/tech/?p=9244.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Academically published myoelectric arm control error rates since ~1980 remain extremely high, far above any real life use requirement, and not even a slight trend to more reliable control in sight: what does this mean?}}, month = {January},year = {2019}, url = {https://www.swisswuff.ch/tech/?p=9244}}


I took the liberty to review published error rates for myoelectric arm controls since ~1980. In other words: how reliable is the myoelectric arm control? How has the reliability changed over years?

This is hard data that is somewhat impossible to negotiate, and it has always been there for anyone to take. So forgive me when I anticipated some clear conclusions from such information over the last years - after all, I figured, a post such as this would not run away ; ) Even though, you must keep in mind that you read this here first as well. As far as I know, despite its ubiquitous availability, and despite a very obvious background or social reason for this (which is yet another subject), this collection of data has not been formally performed before. In fact, word of mouth had it that even decades ago, no self respecting engineer would deliberately enter the field of myoelectric or robotic prosthetic hands, simply because of all options one could do, that certainly was never a prosperous looking one.

The reason for this subject choice is, that I was interested in possibly identifying a trend, or a useful figure, for the reliability of myoelectric arm controls to consider in context of daily use. I used standard key word searches on Google Scholar and edited the resulting publications for relevance. I thus performed more systematically what I had done anecdotally a few years ago when it became obvious that one should not put too much hope into such prostheses, as their ongoing and intractable issues were somewhat obvious all along - at least from view point of a right below elbow amputee performing real work.

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User perspective on the rubber hand illusion in a wider sense – prosthetic arm and ownership for real use [reflection and consideration]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - User perspective on the rubber hand illusion in a wider sense – prosthetic arm and ownership for real use [reflection and consideration]; published January 2, 2019, 22:16; URL: https://www.swisswuff.ch/tech/?p=8882.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - User perspective on the rubber hand illusion in a wider sense – prosthetic arm and ownership for real use [reflection and consideration]}}, month = {January},year = {2019}, url = {https://www.swisswuff.ch/tech/?p=8882}}


The year 2018 was interesting in relation to the rubber hand illusion subject.

I had participated in an extensive interview study regarding embodiment just a year before [link]. Then, I had been identified as a prosthesis "super user" [link] - these people wanted to investigate my type of "embodiment" through fMRI, but we quickly identified my prosthetic arm design (not my brain) as the key aspect regarding the question of why I have a prosthesis that I can actually use rather than just pose with as so many others. My own view here clearly is that if you are after embodiment, you have to go all Sherlock Holmes, you have to go all forensic, all CSI and all crime mystery: and as in "cherchez la femme" when looking for a motive in a crime, it is "cherchez le bras" when studying embodiment: for all issues that center around prosthetic use, go for the core physical aspects first. There are extremely bad things that may, can, and will happen if you do not make that your real first priority. The "rubber hand illusion" is an extreme variation of body ownership of a rubber hand that does not even touch a person and still that person thinks they are being touched if that rubber hand is touched. The illusion to make an amputee believe they embody or bodily own a prosthetic hand is quite different. But both pose risks, whereas the risk that an amputee faces when getting a prosthetic arm that is integrated into his body image has not been considered yet. My slightly experience based consideration proposes that the body image is tyrannically governed, for good and for bad, and if the prosthetic body part - already starting with bad cards, body image wise - craps out, and it always does so far too often, then it draws the hot red angry ire, the depressed disappointment, the falling apart of the cyborg body, of the amputee - and definitely not the cool "oh a neutral object just disintegrated" that one will wish for from a societal, insurance or repair view. The integration into a body image brings with it that the device becomes subject to totally tyranically governed bodies. When it is difficult enough to make any device ready for real world usage, making it ready to survive tyrannies of that nature will be even harder. I proposed an unforgiving approach to failure testing in a recent paper (link) but I cannot say that paper has been greeted with any enthusiasm by the industry that actually builds prosthetic arm components. Because they get to directly face the anger, hate, and rejection of all the users that they had not informed well of just how fragile their prosthetic arm parts really are (link), and they are in absolutely no position to technically improve these parts. So, manufacturers go into hiding. They do not want many users - they want users that buy and do not complain. The last thing they need is a hard bright unforgiving look into just how bad their engineering is. Every non-user, every rejector, should be cautiously left alone, not recruited to wear a prosthesis - because the risk is considerable (link). Researchers currently have the problem that amputees run away, everywhere (link), also because we are continously treated as mentally incompetent. So in essence, we are a group of people that increasingly realizes the extent to which we are being fooled, being had, told stories, and increasingly, we are getting critical. Potential rubber hand illusion switches, dragged to market to be soldered into prosthetic arms, if ever they are a medical treatment or a part thereof, will have negative effects as well: what are these? What do we know about deeply problematic aspects of bodily ownership? I had been invited to talk about that aspect for a group of people interested in robotic control and user interfaces, on December 7th 2018, in Mannheim (Germany). The presentation that I gave now is typed out here in more detail for further reference.

Rubber hand illusion is an idea that, by and large, was somehow transformed into multi-sensory rubber hand illusion, and they now want to put it into prosthetic arms to make users believe the prosthesis belongs to their bodies.

With that, rubber hand illusion goes to market1)As in: piggy goes to market..

This is not really that fascinating. While I am not interested in prosthetic arms because I find the field fascinating, I have been drawn into the field due to circumstances. And as much as you feel that I am locked into this constraint space of shared idiocies, dreams, hopes and failing hardware together with you, in some type of brotherhood by bad fate, you may also realize you are locked into this with me, as consequence of bad fate. Those then are also circumstances. As I deal with it, you may also have to find a way. If you think that is uncomfortable, send me a mail, so we may talk about uncomfortable a bit.

The ultimate consquence of this piece of reflection is not at all bad, however. We will see just how too much "ownership" has bad aspects as well. It risks to slip prosthetic hands into a domain where it is subject to the most vicious decision making that there is: tyrannic and wilful, impulsive and emotional decision making within one's own very personal domain of body or body image with owned body part dependent urgencies and requirements. To withstand these storms, a  prosthetic arm has to withstand not only the physical requirements of real life use (which it normally does not to a degree that will make your jaw drop), it also has to be acknowledged in that capacity by manufacturers and care-givers, emergency teams or repair units, where none of similarly urgencies are currently provided.

To even reach a level of "tool", to be useful enough to be accepted as technical solution (not as embodied "owned" limb), a typical prosthetic arm may have to undergo a most serious metamorphosis, from commercial parts (link)(link) to tuned and optimized parts (link). If you are in R&D and want to do something good in support of arm amputees, it may be relevant to address actual issues such as failing devices or phantom pain (link), before going all out on a limb and drag ill-defined concepts to a domain where they may wreck more than they really help.

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Footnotes   [ + ]

1. As in: piggy goes to market.

CE marking or norm in relation to components for prosthetic arms

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - CE marking or norm in relation to components for prosthetic arms; published December 25, 2018, 15:20; URL: https://www.swisswuff.ch/tech/?p=7749.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - CE marking or norm in relation to components for prosthetic arms}}, month = {December},year = {2018}, url = {https://www.swisswuff.ch/tech/?p=7749}}


CE-marking or norm

The CE-marking establishes that a particular item or product conform to European product law in relation to health, safety, and environmental protection standards [link].

As this text is not public or may be hard to get into the public eye, why not just go ahead and drag it out. I started to be interested by the backgrounds of what our prosthetic limbs and their technical documentation ideally could be already a few years ago [link].  So, a few blog posts here do have a long history, longer than others, and were assembled over quite a period of time.

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Coping with my own phantom pain {update: vascular congestion and cold skin: compression really helps}

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Coping with my own phantom pain {update: vascular congestion and cold skin: compression really helps}; published December 17, 2018, 22:07; URL: https://www.swisswuff.ch/tech/?p=9034.

BibTeX: @MISC{schweitzer_wolf_1561456828, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Coping with my own phantom pain {update: vascular congestion and cold skin: compression really helps}}}, month = {December},year = {2018}, url = {https://www.swisswuff.ch/tech/?p=9034}}


I have gone after possible sources of my phantom pain, over the past years, to better cope with it.

There are aspects that I can influence directly, and others that I seem to be able to direct only indirectly.

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