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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_1571792604, 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.

Point 1 - device description

The TRS Jaws has a metal body and plastic surfaces for the grippers. There is a single spring contained inside. Its pull strength can be adjusted with a lever (see image below: A), from really low grip strengths to somewhere past 5 kg [link]. There is a compression / clamp type swivel mechanism that allows some degree of wrist angle change; it is adjusted simply by applying pressure against that joint (image below: B). I bought it directly from TRS [link] for around 1200 USD.

Point 2: if you only can buy one (1) device, this may be it

Grips - geometry and device cover

Now, grip geometry - shape, materials - can make up for grip strength, or, fail a strong gripper. Check this post about the correlation of grip strength and geometry [link].

This means that, for example, a metal hook with 8 or 10 kg of insane rubber number enhanced grip still may be unable to hold on to a heavy smooth object - whereas a soft deformable surface (such as the ones that I proposed for the V2P Prehensor [link] or the Toughware Equilux [link]) may go a long way towards making up for relatively low grip strengths. It also means that an iLimb, despite a halfway soft covering, still cannot reliably hold a spoon or a hammer [link] - particularly if the handle / stem of the hammer is thin and the hand is unable geometrically to cover that type of object shape, grip wise.

But this device, the TRS Jaws?

Damn. I first thought this was never going anywhere with "just" 5-6 kg [link], but I found that first consideration was dead wrong. The grip shape and the covers appear to be so well adapted to what I do, that I was not even able to put it down.

Performance markers

You do not pick TRS Jaws - TRS Jaws picks you #truecyborg #prostheticarm #prosthetichook

In short, I have been using this device since the day that I got it. I was not able to put it down. Some performance markers for this device are:

  • You do not pick TRS Jaws. TRS Jaws picks you. One glance at the new release post that the device was out and I preregistered then ordered. Then it got here. And so previously, in times before TRS Jaws, I had to only fasten my wrist ring connector screws (that came lose due to vibration such as industrial level typing, etc), once every half year or so. But with this device? Screws came lose every 3-4 weeks, that was how much more activity happened. That screw losening interval may well serve as an indirect performance marker for heavy bimanual support work. TRS Jaws nudged itself into my closer acceptance, all by itself. It was as if this device nudged itself into maybe six times as many at least moderately or significantly heavy grip situations as any device I had before. It was like it wanted to grip more stuff, better, more reliably.
  • Heavy lifting (equipment / boxes, bodies, etc.) was possible with far greater ease. Thing is that the relatively wide surface distributes pressure better than a thin metal hook. Also, the geometry is ready made for PVC boxes that I use for work stuff.
  • The heavier the work that the device flawlessly delivers the less overuse pain you get. Of course you need to overuse first in order to ever note a difference - so a large number of people (that never go there) will not find this relevant. My neck and shoulder region, mostly very tense after every 1-2 weeks of very heavy work, was not tense at all the last few months despite a full on work load. I would have to take a hot bath every 1-2 weeks at least in order to survive the asymmetry pains. Now, no hot baths any more. Hard to relate to other people, how that is extremely useful as a person to wear a prosthetic arm every day if serious lifting is in order.
  • The better the grip, the better the survival of critical objects that are held, gripped, handled. Items of value [read details below] were dropped not at all with an extra margin of safety any more. No cell phone or wallet drops, not even near miss drops, no high end camera near miss drops. This is extremely valuable as well.

New order, new rank

  • It is the device of choice to wear, it pushed the Toughware Equilux (almost) to rank 2. For our hiking and biking holidays, I brought both - the Toughware Equilux is still a bit better for biking as it has the voluntary closing control option that is indispensable for extreme grip strength application [link] and its Trautman hook related shape that locks the handle bar passively.
  • The best device for kitchen or dinner table knives is still the Hosmer Model 5 hook. So that goes in the bag as well. And the only device that a self respecting heavy worker with loads of real work and real action can wear that does look like a human hand is the Becker Mechanical hand. So that is the list for now.
  • So, new list of preference:
  • 1 - TRS Jaws & Toughware Equilux
  • 2 - Hosmer Mod 5 & Becker Hand
  • 3 - TRS Prehensor
  • 4 - Special grip devices: Toughware Retro, Hosmer Model 6 Backlocking Work Hook.

Point 3 - use examples

The device is so good I almost forgot to take a few miles of photos, as I did previously with other devices. Also my action camera had died so I needed to first obtain a new one.

Here is holding an electric screw driver. Snug as shit. No drops, ever [link]. Not dropping this relevant device is paramount, as it is so heavy that if you get it onto your toes, toes hurt and maybe not good for device.

Here is holding an expensive DSLR camera (Nikon D750), Snug as shit.

Why is not dropping this device important? You should know off-hand. If not: revise your "taxonomy", dude.

Here is carrying wallet and cell phone while exiting car.

That is a particularly critical grasp. First of all, any insurance may not insure mishaps, damages, accidents that occur "while entering or exiting a car". Thus, a cell phone drop at that moment may be particularly expensive for the owner. Secondly, if ever you drop a wallet next to a car and content spills and rolls under the car etc., good luck with rearing the car out over that and getting all items back together. Last but not the least, elbow is bent in various positions, arm is being moved - so try that with a myoelectric arm with no unintended device opening / items dropping as consequence of limb positioning artifact. And so despite the apparent harmless nature of that grasp, this one is a bit of a relevant and difficult one, at the same time.

As we see, no problem at all for TRS Jaws. Snug as shit.

Next image sequence - below - shows me trying to fish out the cell phone while keeping the wallet in the grip of the device that works like a charm, with elbow bent while walking. Snug as shit, again.

I know.... no one in "academia" "formally tests" these limb positioning artifacts using valuable everyday items, such as a cell phone and a wallet. Maybe that one is not even difficult enough, who knows. But we have it in black on white that "academia" does not care about testing using relevant error rates, and, that they do not get myoelectric error rates right, dimension wise. So no wonder they cannot improve, ever.

The high degree of reliability of such notoriously critical grips as this, not in a laboratory but in everyday life, under heat or very cold conditions alike, with or without sweat, with dry, greasy or wet skin, and even with a lot of sweat, are required to prime my brain into accepting a prosthesis as a tool if not body extension that it automatically considers for grasps - and real time speed and reaction of the control will be a next factor to discuss [link], if ever. Not that you necessarily knew how to build a really reliable body powered prosthesis, and not that you actually wanted to know how prostheses are successfully integrated into a body scheme [link][link] ; ) I guess you'd a asked before, anyways.

Here is carrying a heavy laundry basket two floors up. Snug as shit.

When riding a mountain bike, holding on to the handle bar is one thing. Works, snug as shit.

But if you need to change position, ... I need to let go then ride single-handedly for a while then be fast to grab the handle bar again. Fast and then snug as shit.

Riding a road bike with a drop bar is another thing though. Snug as shit, too.

Shift grip from lower to higher position while riding - flawless.

Point 4 - use and performance scales now have a new standard

If you "test" these things for a living and these don't win in your world of "testing", you test wrong. Non-negotiably. If you cannot understand how orthopedic correction and support and prosthetic performance rely on each other, then you may want to consider doing something else at this point: simply far too much was said (or written) already to explain all that [check e.g. the technological aspects as seen through true geek eyes such as a parallel to Alex Roy]. Sorry.

You test wrong if TRS Jaws does not win #cybathlon #bettercyborg #truecyborg #understandingprostheticarms

You may actually get left behind, if you don't understand this. Not now, not tomorrow, maybe. But when I, having routinely handled even past 100 kg of weights, will not need shoulder surgery some day, but you will, not having handled nearly as much. Just so we addressed that too.

Point 5 - they totally did get the Cyborg angle this time!

It is one thing to have a device that does not perform but that is used to play Cyborg [see intro to my concept of "Extreme Cyborging" here], to use it for future role model cosplay - such as the "bionic" hands worn by contemporary "ambassadors" for that type of under-performing technology. There, the problem is ultimately that given the bold "promises" these devices come with, if ever one wants to promote these boldly advertised claims, one might be forced into a role as a phony, a braggart a showoff, a poser, a swank, a tinhorn, a gobshite, a grandstander, in other words, a fake, a puppeteer really. Not that there is a problem with puppeteers in general - all fine, I have such a device, I know what it can do but far worse, I have a pretty good idea about what all it cannot do. So, for example, these "bionic" hands with their somewhat ill-devised grip geometries [link] that are controlled by inherently faulty myoelectric controls [you may really want to read about these problems here] do not lend themselves for much else from view of real work than for scripted gesture play [link]. If anyone can actually try to wear myoelectric arms and hope for at least reasonable success, check the sub-population with the lowest sweat rates [link]. You will have realized that yourself already - because, to recognize that, is also not very hard [link][link].

You can't make people smarter. You can expose them to information, but your responsibility stops there. Mark Rippetoe

It is another thing to wear a prosthetic device that in fact outperforms human hands - and if only for some individual tasks such as touching hot stuff: like, a metal split hook [link]. For possibly silly but rather deep reasons [link], "academia" does not seem to recognize any of these advanced modern [link] gripper devices as true transhumanist evolutions or as improvements in a deeper sense or as futuristic work adaptations for a better than real human that we we hope to become but will never be [link][link]. That is interesting because that is where the obvious and the "academic" provide a stunning absence of apparent intersection.

And the TRS Jaws?

(I was a bit tired from Extreme Cyborging on my new bike [link] and thus this may look too relaxed for your taste) (but: so what?)

The TRS Jaws device totally performs and it looks the part - far beyond what the most courageous of guessers ever could have assumed [link]!

More than one person that had previously never commented on my prosthetic arm now almost accosted me: their eyes fell out, they keeled over, they were positive about this device like no one was ever positive. They could not contain themselves, like, just "how bionic" the TRS Jaws looks. WTF. They were anxious to tell me that even at the unlikeliest moments. This device pushes things home in unlikely ways: it resides on the left / sunny side of the Uncanny Valley curve, there, where no one of the military-space-technology guys is looking (they always seem to dig on the shady side, there where anthropomorphic hands are placed). And while our planet sure has its share of self-proclaimed "Bionic Men" [link][link], a themed type of cosplay role, turns out this one actually is for real men, which still is totally not the same.

Just yesterday I was in a shop trying on jackets - also cleaning up after myself, that is, closing zippers and returning jackets onto the coat hangers with my TRS Jaws, far faster and far more fluent than any of the contenders as of recent times [link] - when another customer got stuck staring at me [which may have massive consequences in relation to interpreting, say, the Cyborg Manifesto in relation to the actual impact of technology such as this], with the one earpiece / temple of her reading glasses hanging from her left mouth angle. It would have been a sight for the gods. When I did catch her stare, she became unstuck and stuttered that "it was impressive to see how I managed to .." etc., so I replied that I found it "far more impressive to see how she managed to stare so persistently without dropping the glasses from her mouth because that was something most people could not pull off". After all it was not by the sound of "clunk" that I had noted her presence. Her further attempts to form sensible sentences faded away, and she then inched her way out of there. That is the type of situation that a TRS Jaws can get you in.

If ever 2019 has a prosthetic fashion item that is absolutely indispensable if not just for pure function but because of its raw dedication to this aspect (you just scrolled across the text and images above without actually reading, right?) but also to make believe you can handle stuff manually because you actually can, it is clearly the TRS Jaws. They entirely outdid themselves, this is a stunning piece of industrial design. As a visual statement, it is far bolder than any anthropomorphic prosthetic hand, while it is truly water proof, truly functional 24/7, truly robust and truly worth its money. It is the first prosthetic arm device that is a symbol because it is not [link]. Thus it requires and deserves a real human to wear it, one that milks existence for raw real work performance.

But be careful: while wearing a Red Hand at the time when I invented that as an idea (late 2008 and then 2009) [besides: why red?] required at least some balls to wear, this may require even more balls - as it is truly more than a real statement: it is a real thing. Because once you wear one of these, other people may not want to help you stash a few heavy boxes any more. Instead they will think you are now good to go all by yourself - then you have to work that one out yourself. Which is not just a small price to pay for true manual competence, but the path you actually wanted to go. Didn't you.

Disclaimer: and so, I paid for the device, the first version of it had a flaw that I identified immediately, that I fixed myself with some nifty fix, I paid to ship it back and they implemented the fix using machined parts that are even better and sent it back to me. Now, this one certainly has gone to hell and back so to say before I started to consider it. That was between February and May 2019. it is routine that I trash a device on first touch. But very rarely a manufacturer gladly fixes a device so it works better under full loading, and almost never do they do that immediately. So, TRS outdid themselves entirely. They are a great badge to wear as they do look out for hard work, real work, and high loads. With that, I am afraid that I am not an ambassador but rather free in what I identify as good or bad. Just so you consider that in your considerations.

3 Replies to “TRS Jaws [new product - first use report]”

  1. This is a great review, Wolf. Very fun to read. Yesterday I got a great reaction from a kid at a gas station who was over the moon about my prehensor. I'll have to return after I get the Jaws and see what he thinks about that!

  2. I saw the Jaws at the Amputee Coalition Conference in San Antonio. I am in the market for a new body powered prosthetic suspension system, since I use a suction system, that is not meeting my needs. I stopped in at the TRS booth since I have a Hammerhead (https://www.trsprosthetics.com/product/kayaking/) that I use for Kyaking about 4 times a week in the Summer time, I use the Dragon for Yoga / sking (https://www.trsprosthetics.com/product/martial-arts-sparring/), and use the multi d for Yard Work https://www.trsprosthetics.com/product/multi-d-terminal-hand/. I also have a ottoboch myolectric that I use some times for driving, but it gets no where near the use of my sport arm. In any event Bob Radocy (founder of TRS) was there, and I geeked out with him for over an hour about how much I like their products. He was by far more helpful, than any of the vendors there talking to me about sleeves, and the pros and cons of each. (He does not sell sleeves / liners....) In any event, I got to play with the Jaws, and it will be the primary terminal device of my new arm. It was funny, in that I really was not even there looking at this type of product, and I was very impressed.

    I will scour your web site for your thoughts on suspension/liners. (I have not been on the site for a few years...) I am leaning pretty heavy towards two bolo systems for the upper and lower arms, and a very thin silicone sleeve. Any thoughts?

    Thanks for the site, I always appreciate your brutal honesty.

  3. Suspension: we nerded out the subject in our scientific article that got published (free download: https://jneuroengrehab.biomedcentral.com/articles/10.1186/s12984-017-0340-0) but the checklist rundown is here (https://www.swisswuff.ch/tech/?p=32) and the tube gauze to go under the gel liner (Alpha liner) is described here (https://www.swisswuff.ch/tech/?p=2727). Regarding brutal honesty, the thing is that once one MUST deliver heavy sweaty precision grip / lift work, one cannot afford the courtesies of praising engineers that build crap or of manufacturers that build stuff that costs a fortune and requires weekly babysitting. There is just simply no capacity for that here. -- The approach to build a fragile gripper and tell people "it is the little things that count" is absolute utter rubbish. Once you wear a device that bathes in absolute grip power, you can checkmark all the little things off the list within split seconds and then spend some hours with the larger things. These are the ones that put the big big smiles on one's face, even years later. So, good luck with the device.

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