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Category: Asymmetry

TRS Jaws [new product - first use report]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - TRS Jaws [new product - first use report]; published August 10, 2019, 10:51; URL: https://www.swisswuff.ch/tech/?p=9769.

BibTeX: @MISC{schweitzer_wolf_1573560205, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - TRS Jaws [new product - first use report]}}, month = {August},year = {2019}, url = {https://www.swisswuff.ch/tech/?p=9769}}


3 Comments

The TRS Jaws is a voluntary opening gripper where you can set the grip strength by a lever. The grip then varies between very light, maybe under 1 kg or so, to somewhere above 5 kg. This is a first real use report, after I used it permanently since roughly around May 21, 2019, give or take a few hours.

There are just a few points to address at this stage. If you wear a body powered arm for real work [link], you may now buy one.

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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_1573560205, 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.

While others keep rambling about compensatory motion [1] where they assume the "cause" to reside inside some extra joint or so, I know, from exposure and from intelligent looking (all that is needed, boys1) that the orientation of the grip angle and shape in relation to the fixed gripper geometry - including wrist rotation - has to work in conjunction with the average orientation of objects in everyday life, work, tasks and jobs. Not everyone understands adaptive or adaptable grip really well2  when really, modern "bionic" prosthetic hands have an electrically controlled adaptive grip that, by definition of "adaptive" (and not: "adaptable" [1]), closes fingers around any irregularly shaped object - just like, since maybe 1938, the Becker Mechanical hand does. So there is nothing new at all with regard to that. With regard to device-angle constraints, adaptive grip options do not change that really. The typical "tests" (ULPOM, SHAP, etc.[1]) do not produce output that forces the examiner onto the answer of "there, angles, you... you" so one is thrown unto oneself yet again, so to speak, in order to shed light into this aspect.

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 - also with regard to angular constraints - 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 particular imagination, thus it is reportedly old, very old indeed, not new, like some uninformed people try to promote. Conversely, split hooks are so transformative and groundbreakingly new that not even the self-proclaimed transhumanists have understood, or adopted this concept. In a way, a split-hook efficiently unmasks a number of wrong beliefs - just look at their faces, listen to a few sentences of these mouths, and you know more about them than they ever wanted to admit.

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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[1] P. J. Kyberd, "Assessment of functionality of multifunction prosthetic hands," JPO: Journal of Prosthetics and Orthotics, vol. 29, iss. 3, pp. 103-111, 2017.
[Bibtex]
@article{kyberd2017assessment,
  title={Assessment of functionality of multifunction prosthetic hands},
  author={Kyberd, Peter J},
  journal={JPO: Journal of Prosthetics and Orthotics},
  volume={29},
  number={3},
  pages={103--111},
  year={2017},
  publisher={LWW}
}

Embodiment of a prosthetic arm [reflections, thoughts, considerations]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Embodiment of a prosthetic arm [reflections, thoughts, considerations]; published September 16, 2018, 15:42; URL: https://www.swisswuff.ch/tech/?p=8513.

BibTeX: @MISC{schweitzer_wolf_1573560205, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Embodiment of a prosthetic arm [reflections, thoughts, considerations]}}, month = {September},year = {2018}, url = {https://www.swisswuff.ch/tech/?p=8513}}


So, apparently I had been "identified" as a "super prosthesis user" by a group of researchers. And I was invited to talk about embodiment in context of the "rubber hand illusion" at a user interface or robotic control workshop [link].

So is that what I am: a "user"?

Tsk.

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Modifying Shimano Ultegra road bike setup on a Colnago C40 for left handed use - second approach [technical right below elbow amputee core focus work / bike adaptation]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Modifying Shimano Ultegra road bike setup on a Colnago C40 for left handed use - second approach [technical right below elbow amputee core focus work / bike adaptation]; published January 27, 2018, 15:30; URL: https://www.swisswuff.ch/tech/?p=8196.

BibTeX: @MISC{schweitzer_wolf_1573560205, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Modifying Shimano Ultegra road bike setup on a Colnago C40 for left handed use - second approach [technical right below elbow amputee core focus work / bike adaptation]}}, month = {January},year = {2018}, url = {https://www.swisswuff.ch/tech/?p=8196}}


After a first approach, where also the history and idea where it came from is detailed [link], I now set up and tested a second approach to modifying my Colnago C40 carbon bike with a triple chainring Shimano Ultegra chainset.

The extensive testing of my first approach that I had performed there lead to a range of concise detailed issues and problems. There were now addressed, all, and thus a second (and significantly better) approach resulted.

As stated before, no disability sports advocate specializing in road bikes and no bicycle mechanic specializing in individualization and custom solutions over the years ever thought this was possible in this way. They all said it could not be done. And I had asked a few of them, since it had bugged me a lot. And as I had sold my Cannondale road bike after the amputation, thinking there was no way, I now got myself a road bike back and decided to go down my own path to really use it the way it is meant to be used.

Generally and as part of riding a road bike, I wanted fast and comfortable gear switching, fast and accessible and comfortable braking, and I wanted to be able to enjoy various and if possible equally comfortable sitting positions or body positions. A great road bike trip may be a lot longer than a fast mountain bike trip into the forest. Last but not the least, as amputee my stump usually would suffer from vibration induced pain after 20 minutes  particularly with hard connectors such as the Mert or Freelock adapters, so padding definitely was an issue.

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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_1573560205, 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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Modifying Shimano Ultegra road bike setup on a Colnago C40 for left handed use - first approach [technical right below elbow amputee core focus work / bike adaptation]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Modifying Shimano Ultegra road bike setup on a Colnago C40 for left handed use - first approach [technical right below elbow amputee core focus work / bike adaptation]; published December 3, 2017, 15:11; URL: https://www.swisswuff.ch/tech/?p=7816.

BibTeX: @MISC{schweitzer_wolf_1573560205, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Modifying Shimano Ultegra road bike setup on a Colnago C40 for left handed use - first approach [technical right below elbow amputee core focus work / bike adaptation]}}, month = {December},year = {2017}, url = {https://www.swisswuff.ch/tech/?p=7816}}


I got myself a Colgnago C40 carbon road bike / race bike / Rennrad for leisure amateur purposes. That is, for the colloquial ride. With that, I am not a professional or competitive racer. Modifying my Shimano Ultegra road bike setup for left handed use therefore aims towards leisure purposes.

How to go about riding a road bike as arm amputee. This is the first approach and test. If you are after the improved set-up, head over to the page with the second approach [link] because that really worked a lot better.

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ADL learning and body powered prosthesis control [paper review]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - ADL learning and body powered prosthesis control [paper review]; published October 9, 2016, 11:42; URL: https://www.swisswuff.ch/tech/?p=6484.

BibTeX: @MISC{schweitzer_wolf_1573560205, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - ADL learning and body powered prosthesis control [paper review]}}, month = {October},year = {2016}, url = {https://www.swisswuff.ch/tech/?p=6484}}


Learning to use a body-powered prosthesis: changes in functionality and kinematics. Laura H. B. Huinink, Hanneke Bouwsema, Dick H. Plettenburg, Corry K. van der Sluis and Raoul M. Bongers. Journal of NeuroEngineering and Rehabilitation 2016 13:90.

Abstract [1]

Background: Little is known about action-perception learning processes underlying prosthetic skills in body-powered prosthesis users. Body-powered prostheses are controlled through a harness connected by a cable that might provide for limited proprioceptive feedback. This study aims to test transfer of training basic tasks to functional tasks and to describe the changes over time in kinematics of basic tasks of novice body-powered prosthesis users. Methods: Thirty able-bodied participants and 17 controls participated in the study, using a body-powered prosthetic simulator. Participants in the training group were divided over four groups and practiced during a 2-week-period either direct grasping, indirect grasping, fixation, or a combination of these tasks. Deformable objects with different compliances had to be manipulated while kinematic variables and grip force control were assessed. Functional performance was measured with the Southampton Hand Assessment Procedure (SHAP) prior to and after the training sessions, and after 2 weeks and 3 months retention. The control group only performed the SHAP tests. Results: All four training groups and the control group improved on the SHAP, also after a period of non-use. Type of training had a small but significant influence on the improvements of the SHAP score. On a kinematic level movement times decreased and hook closing velocities increased over time. The indirect grasping group showed significantly shorter plateau times than the other training groups. Grip force control only improved a little over training. Conclusions: Training action-perception couplings of body-powered prosthesis in basic tasks transferred to functional tasks and this lasted after a period of non-use. During training movement times decreased and the indirect grasping group showed advantages. It is advisable to start body-powered training with indirect grasping tasks but also to practice hook-object orientations. Keywords: Upper-limb prosthesis, Body-powered prosthetic

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[1] [doi] L. H. B. Huinink, H. Bouwsema, D. H. Plettenburg, C. K. van der Sluis, and R. M. Bongers, "Learning to use a body-powered prosthesis: changes in functionality and kinematics," Journal of NeuroEngineering and Rehabilitation, vol. 13, iss. 1, pp. 1-12, 2016.
[Bibtex]
@Article{Huinink2016,
author="Huinink, Laura H. B.
and Bouwsema, Hanneke
and Plettenburg, Dick H.
and van der Sluis, Corry K.
and Bongers, Raoul M.",
title="Learning to use a body-powered prosthesis: changes in functionality and kinematics",
journal="Journal of NeuroEngineering and Rehabilitation",
year="2016",
volume="13",
number="1",
pages="1--12",
abstract="Little is known about action-perception learning processes underlying prosthetic skills in body-powered prosthesis users. Body-powered prostheses are controlled through a harness connected by a cable that might provide for limited proprioceptive feedback. This study aims to test transfer of training basic tasks to functional tasks and to describe the changes over time in kinematics of basic tasks of novice body-powered prosthesis users.",
issn="1743-0003",
doi="10.1186/s12984-016-0197-7",
url="http://dx.doi.org/10.1186/s12984-016-0197-7"
}

Vacuuming with iLimb Ultra Revolution [ADL]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Vacuuming with iLimb Ultra Revolution [ADL]; published February 29, 2016, 18:29; URL: https://www.swisswuff.ch/tech/?p=5727.

BibTeX: @MISC{schweitzer_wolf_1573560205, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Vacuuming with iLimb Ultra Revolution [ADL]}}, month = {February},year = {2016}, url = {https://www.swisswuff.ch/tech/?p=5727}}


Allegedly, one can actually use the iLimb for vacuum cleaning floors. I set out to try that.

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Hard Bimanual Activities (HBM) [overview]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Hard Bimanual Activities (HBM) [overview]; published August 12, 2015, 20:26; URL: https://www.swisswuff.ch/tech/?p=5330.

BibTeX: @MISC{schweitzer_wolf_1573560205, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Hard Bimanual Activities (HBM) [overview]}}, month = {August},year = {2015}, url = {https://www.swisswuff.ch/tech/?p=5330}}


Hard manually hazardous work as unfortunate requirement to arrive at "overuse"

After reading research presented at the ISPO 2015 in Lyon, France, that contends that "overuse" is regarded as consequence of not having a flexible prosthetic wrist unit (link) and that texting is the apparent cause for "overuse" in arm amputees based on somewhat questionable data (link) and after reading that they now are trying to reduce "overuse" through quantification of compensatory motions in the clothespin test by having an amputee report "overuse" after placing clothespins (link), it occurred to me that the authors of these studies, and most likely most researchers in that field, lack tangible experience and knowledge as to what in fact constitutes manual work that lends itself to actual "overuse" (rather than normal strain that happens after a somewhat unusual but quite singular very light weight activity that equates to lifting a fork, a spoon or possibly a tiny plastic clothespin).

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Cocreat 3D [very stylish 3D printing arm/hand startup]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Cocreat 3D [very stylish 3D printing arm/hand startup]; published May 20, 2015, 20:20; URL: https://www.swisswuff.ch/tech/?p=4801.

BibTeX: @MISC{schweitzer_wolf_1573560205, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Cocreat 3D [very stylish 3D printing arm/hand startup]}}, month = {May},year = {2015}, url = {https://www.swisswuff.ch/tech/?p=4801}}


Cocreat 3D now sets out to print prosthetic arms/hands. Great designs! And not just that.

Scott J. Grunewald at 3dprint presents a superbly written article that is extremely unusual for its very authentic and clear content, far off the totally confused if not misguided direction that usual media hypes convey:

While working 3D printed hands and mechanical limb replacements have been getting a lot of attention lately, in reality they aren’t really for everyone or for every situation. Motorized prostheses are extremely expensive, require regular maintenance, and are considered by some people who do not have upper body limbs to be more trouble than they are worth. Many people who are missing arms or hands actually have multiple prosthetic devices for different situations, or even eschew them entirely. Additionally people often assume, if someone is missing a limb or has any sort of noticeable disability, that something happened to them when in actuality it often it is something that has been part of them since birth. The automatic assumption that missing a limb makes someone broken and needs to be fixed is frankly a rather onerous one and it is high time that the behavior be addressed. The fact is, most disabled people don’t have the luxury of “fixing” their disability and rightly resent the implication that they are required to do so. Subtle forms of ableism like excessive displays of pity of being inspired by someone with a disability because they “manage” having a disability can often be rather demoralizing and actually have the opposite intended effect. Whereas someone choosing how to present and acknowledge their disability is actually an important personal statement that shouldn’t be taken from them. So while 3D printing is giving an entire generation of people access to useful and affordable prosthetic and assistive devices, it has also given them the ability to define the nature of their device and customize it to their personal needs. And because 3D printing is so inexpensive in comparison to traditionally manufactured prosthetics, it also offers the opportunity to consider personal aesthetics. It is that new freedom that has inspired a Colombian 3D printing business to create a series of 3D printable prosthetic devices designed to be seen and noticed. “We present a series of 3D printable passive prosthesis designed for upper limb amputees. We aim to make uncommon prosthesis that are not meant to be hidden but to be shown without shame,” explained designer and Cocreat3D CEO Esteban Velásquez Rendón. Cocreat3D is still in the prototyping phase of their design process and currently has only printed scaled down versions of the prosthetic devices, but they should be available soon. The prosthetic devices can be custom fit to the wearer’s arm using 3D scanning and 3D modelling technology, and of course be printed in any color or material desired. And given the wide variety of materials that are available, including metallics, neon, and wood, many of these designs could be quite striking. While Rendón’s devices will not be the first passive or decorative prosthetic limbs to be 3D printed, they are the first that seem to be aiming to create a line of products that can be adapted to any user, not designed for a specific person. And as the cost of 3D printers and materials continues to drop, small-scale, personalized manufacturing is made more accessible to almost anyone. 3D printing technology is leading to the democratization of design and manufacturing and having a very real impact on multiple industries and communities. And now a community that is often marginalized and forced to have their mobility, experiences, and lifestyles defined for them is being given the tools to take that power back for themselves, even in such small, seemingly insignificant (to those without disabilities) ways.

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Asymmetry due to below elbow amputation and consequences [analysis]

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Asymmetry due to below elbow amputation and consequences [analysis]; published December 10, 2014, 20:10; URL: https://www.swisswuff.ch/tech/?p=3789.

BibTeX: @MISC{schweitzer_wolf_1573560205, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Asymmetry due to below elbow amputation and consequences [analysis]}}, month = {December},year = {2014}, url = {https://www.swisswuff.ch/tech/?p=3789}}


Asymmetry causes long term problems. Not wearing a prosthetic (at least over a longer time) is not an option. Overuse [link] and back problems are a serious issue. While overuse of the other / remaining / "intact" arm and hand is one aspect, asymmetry is the other aspect.

Both aspects require prosthetic arms to be comfortable to wear, and to be - grip wise, push wise, hold item wise - functional in an everyday sense. Any other type of prosthetic arm will be discarded or not worn in the long run, and thus not offer sufficient function to take load off the other overused extremity.

Both asymmetry and overuse as serious long term problems are usually neglected in current prosthetic arm design.

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What does Otto Bock mean by "significant benefits" with their Michelangelo hand?

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - What does Otto Bock mean by "significant benefits" with their Michelangelo hand?; published November 3, 2010, 05:31; URL: https://www.swisswuff.ch/tech/?p=363.

BibTeX: @MISC{schweitzer_wolf_1573560205, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - What does Otto Bock mean by "significant benefits" with their Michelangelo hand?}}, month = {November},year = {2010}, url = {https://www.swisswuff.ch/tech/?p=363}}


[Find all articles about the Otto Bock Michelangelo hand]

In their ISPO World Congress 2010 Leipzig contribution, Otto Bock stated their Michelangelo hand would show significant benefits for arm amputees.

After an initially very appealing presentation of the Otto Bock Michelangelo hand, absence of further functional improvements at the Leipzig 2010 exhibition appeared to miss out on some functions that we would expect by now, given that 2008 research already reported some of these. Also, the Otto Bock Michelangelo hand is *not* thought-controlled as some may believe.

So when I see my prosthetic technicians spending their time traveling to Otto Bock Michelangelo demos, instead of conducting seminars about how to build better body powered arms, and instead I find myself in my own work shop every now and so often, revising their work, fixing their work, coming up with the technical designs they would be paoAs rotatory cuff problems are one of the bigger and more neglected aspects, improvement of shoulder strain certainly would count as significant. For that, grip geometry and weight are key issues.

The following video shows a Otto Bock Michelangelo hand demonstration.

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