In order to allow future reference, I here post questions and my answers to these questions as mailed to me last week by a person claiming to be a 17-year old high school student. So far and by and large, I had that type of questions asked by academic researchers - as scope, wording and level of detail are typical for those.
The times when one knows who asks what are long over. Welcome to the Brave New World. I truthfully answered the questions based on what we already know.
Keywords high school project prosthetic arm prosthetic hand prosthetic hook control academic research project sensory feedback prosthetic gripper robot arm robot hand amputation amputee arm below elbow
The mail stated:
Please talk about your own experiences and opinions when answering the questions. The more elaborate the answers are, the better. Also, I’m sorry if some of the questions are already answered on your website. Thanks! I truly appreciate it. Questions:
- What are the most important movements that a prosthetic hand has to make?
- Were you right-handed before your amputation? If so, did that change?
- What do you think are the easiest/most effective ways to ‘control’ a prosthetic hand?
- For example, could you give your opinions about:
- What are the biggest problems with having a prosthesis?
- Do you think the looks of a prosthetic hand are important? Would you like to have a prosthesis that resembles a human hand?
- Would you mind having a mitten-like shaped prosthetic hand? Or a tweezer-like prosthetic hand?
- Is it important for you to be able to do precise things with your prosthetic hand? For example, writing a text message or typing?
- Would you prefer a ‘hard’ steel-like hand or a softer more skin-like hand?
What are the most important movements that a prosthetic hand has to make?
Open and close.
I did have my "bionic" hand to employ the custom grip function to flash a middle finger for a while. But that grew old real fast.
Were you right-handed before your amputation? If so, did that change?
It depends and there is not a straight answer. Yes and no.
If anything really changed it was that the arm stump is far less able to sustain actual injuries than a hand. Now, prosthetic arms are never built for "ultra extreme active usage" and that sets in motion the downfall: I will not wear the prosthetic arm for real action, but real action causes real rub off and damage to the whole body including the arm, and logically when I have burns, frost bite, lacerations etc. on my stump, and an active life style causes these repetitively, then longer healing time will prevent me from wearing the prosthetic arm even more. Logically, the more active I am, the more time I spend not wearing the prosthetic arm an even disproportionally longer way, the more I get automatically used to doing things differently, and the less I depend on a prosthetic arm.
With the effect that on Saturday I tested my girlfriend's recent mountain bike for some more demanding ride sections, without wearing a prosthetic arm. Once it has come that far, it will be difficult to tell me what I should wear, or, what the concept of right and left handed should do for me.
If they want me to develop a true sense of ownership, the prosthesis must match the way I terrorize myself.
What do you think are the easiest/most effective ways to ‘control’ a prosthetic hand?
Easy / effective are difficult adjectives in terms of a prosthetic arm because the actual constraints are severe. Most importantly, easy most effective - for whom? There actually exists no such thing as a clear answer.
What is overall very "easy" and "effective" for me is an arm that is reliable, works for a long time without repairs, has a good distribution of weight about it, supports particularly hard repetitive activities and that I do not have to worry about all the time. Really building a useful prosthetic arm under these definitions is hard work and the customer - me - is critical, and fast to cause more damage. As prosthetic technicians earn 30% on all hardware sales, that definition is neither easy nor effective for them. Just for me : )
What is being sold as "easy" by academic research is an arm that can be used without any particular mental effort inasmuch as open/close is concerned, but I have yet to see one that does not totally suck in every other regard. Academia tells us we can have "easy" control with neural implants (ouch); last time I discussed "ease of control" was with folks of the Artificial Intelligence laboratory at the University of Zurich. I helped them find a prosthetic technician that made them a test socket so they could also wear their model of "Smart Hand" as they believed that was the pinnacle of easy control and sensory feedback, and as far as I was told the fittest of their research crew was able to wear the 7 kg setup for 20 minutes before breaking down and sweating profusely or so. Ah and they closed down that Artificial Intelligence center.
"Easy" and 'effective' for the prosthetic industry and technicians are massively overpriced myoelectric and bionic gadget hands. As prosthetic technicians take 30% of hardware without even work etc they bill, a hand for 80'000 USD is far better business than selling a 400 USD hook, and worse, the hook lasts for 8-12 years or so but the hand survives 1-2 years maybe. Secondly, building a really well functioning body powered arm actually requires real mechanical understanding, whereas glueing together parts of a myoelectric arm does not. It is a lot easier for technicians to build myo arms, so, "easy". Then, the arm amputee will not be able to really wreck the myoelectric arm as by definition, anything that damages the prosthetic arm is exaggerated or extreme use and not insured, so that is "effective damage control" and simply restricts the amputee's lifestyle. Read the fine print on Otto Bock parts and you will find that once you actually do something and the sucker breaks, you should not have done it in the first place so it is not covered by warranty. Read that again, yes, quite idiotic from user viewpoint. With that, arm amputees wearing such parts will refrain from anything close to "actual activity" and that avoids confrontations about actual performance totally. Very "easy and effective" money making. In essence, a bionic anchor that ties you down to achieving no manual work any more at all is easy and effective for the industry and while you might call that a bit cynical, the prosthetic component industry is not so much about making arm amputees go wreck landscapes, but to earn money.
Then, what is "easy and effective" in relation to lifestyle as such. See, with two hands I would easily and effectively grab my mountain bike, do a combined ride/hike up on Val Sinestra up to Fuorcla Champatsch, there be snow already, and then I would use my bike to slide down the slopes, then downhill ride it down some steep alpine forests until back in Scuol. Later one would head to a golf driving range and hit a few dozens of balls. Far far off the beaten path, altitude difference 2000m. I played bluegrass picking twelve string guitar with real ease. You have no idea what two hands REALLY can do with total ease unless you did it in a totally comprehensive way. So the terms "easy" and "effective" to me have very real connotations.
My perception of alive, easy and effective is NOT schlepping fragile heavy stuff; that are parts I consider dead weight. People these days are told by academic research that neural control "like using the hand before it was amputated" was "easy" but this term only focuses on one tiny aspect of the actual control issue while the rest is a total drag in any aspect conceivable. Such a hand also will be one of the current "bionic" hands or so, and they are both far too fragile, too weak and useless and too heavy.
Some people regard the mere walking with a long sleeved jacket on as the pinnacle of maximum activity. Then the above said does not apply. If that is the type of view on life you are after, head on over to some blog website that details their adventures. Then you are on the wrong page here. Remember? You came here, by yourself.
For example, could you give your opinions about:
a myoelectric prosthetic hand, controlled by nerves higher up in the arm
Myoelectric hands one will consider once "nerve control" allows actual sophistication in control are hands with individual finger motion - these look great but their grip force and precision is at the current moment a total joke. If all you talk about is "open" and "close" then body powered arms are miles better. Myoelectric control issues even for open and close are not worth discussing. Given that there are no paradigms to power and build really good five finger prosthetic hands, having neural control rather than a cable control does not seem to give any real advantage. The procedure of neural implants is risky, painful and given absent real uses not worth it.
a prosthetic hand controlled by the motion of your own upper arm
Probably extremely limited / niche use. Unless you can use your upper arm in a totally isolated way like a belly dancer uses their isolated belly.
Always think "full glass, water about to drip out, balance that glass over laptop computer". You want to carry and hold that, then release by wiggling the upper arm? This results in a very unstable control situations as both grab and release aiming and performing usually have to be possible with ease and precision.
a prosthetic hand controlled with pressure sensors, so it would grab something you touch
Not sure that grabbing something you touch is what pressure sensors really do. The Otto Bock Sensor Hand Speed had slip control built in, but as far as I heard users switched that feature off because of irritating malfunction. I regard pressure sensors for force feedback as added weight and added overhead to already useless electronic technology as far as current models are concerned.I did participate in sensory feedback research and all that prosthetic sensory feedback achieved was a serious increase in phantom pain, so I would start to ignore the pain and sensory feedback, resulting in higher sensory feedback pulses, ultimately resulting in a pain catastrophe. These days I would pay extra NOT to have to wear sensory feedback with electronics. People usually have not the faintest idea about a body powered arm. No extra / added sensory feedback is even needed here. - I have a useful estimate of hook tip position even without looking; not perfect but enough to type well. I have a very hard hook - wrist - socket- arm connection that gives useful and enough force, touch etc feedback. Enough for what I need to use the arm reliably and well.
a prosthetic hand controlled with a remote control, by your other hand
Funny, the iLimb Ultra Revolution has that. You can use the iPod or iPhone to remote control it. Now, a very realistic situation that I actually did in that way a few times:
Without prosthetic arm
m:ss,hh (minutes seconds hundreths)
0:00,00 Decision making I want to take out the garbage.
0:00,50 I get up to get the garbage bag.
0:05,00 I have the garbage bag removed from the kitchen
0:50,00 Garbage bag tied up.
1:10,00 I have put on flip flops and on may way out the door
1:45,00 Garbage bag carried out, dumped, I am back.
With "bionic"arm with different grip patterns:
0:00,00 Decision making I want to take out the garbage.
0:00,50 I get up to get the garbage bag.
0:05,00 I have the garbage bag removed from the kitchen
0:05,10 Start trying to change / switch grip pattern in hand to allow tying up and grabbing string
1:30,00 Hand restarted once, grip patterns never change, system locked up.
2:30,00 I have tied up the bag without any useful grasp pattern of the hand, as it blocks me and cannot stabilize the string in a very useful way
2:50,00 Flip flops on, way out the door
2:51,00 Trying to switch grasp pattern of prosthetic to allow for bag carrying
3:10,00 Epic fail again, no use trying any of these double contraction or iPod attempts
3:45,00 Garbage bag carried out, dumped, I am back.
Working the "bionic" remote control arm takes AGES longer, it is complicated, and also is far more uncomfortable.
It is only hard to understand why the complex fragile and still cheaply made strategies for these arms suck so very much if you do not have one. The everyday pitfalls are one constant series of real nightmares. That stuff holds so much gadget promise and at the same time does not deliver it to an extreme degree.
What really would be useful would be a physical switch on the prosthetic arm and a tiny LCD display to switch / show the program or grip you currently use. Similarly to how Casio watches are set up - totally simple, logical, and useful. And at least "immediate".
But they are not accepting such requirements from a person with a handicap. Usually, prosthetic manufacturers think they come up with really cool solutions, but, what the person with the handicap actually wants, needs, and requires, is not respected too often.
Of course, "remote control" etc surely has aspects of "cool" but as I wear the stuff on my body, why would I need a "remote" control. Like, has anyone ever considered, at least for split seconds, what the word "remote" really means? Am I "remote" to my arm? Really, now.
I also told the iLimb representatives that the loud sound of their hand's motor was a real problem. They never bothered to change that either.
a prosthetic hand controlled by sound/voice commands
That is probably the most prized question. The question is what one can build, and what works.
What are the biggest problems with having a prosthesis?
Currently, I optimized my body powered (cable controlled) arm with a number of own innovations, and it is comparable to the relative performance of a 12'000 USD custom built ultra light maximally tightly controlled race bike. So for body powered technology, I consider that optimized rather well so far. We currently have further ideas that we develop but too early to advertise. We also avoid friction rash, nerve compression and I can work over the shoulder or even head level, things others cannot do with their body powered arm.
My "bionic" arm causes shearing blisters and real pain on the stump after say 4-6 hours of actually no work. It cannot be used for the most simple tasks because grips are totally unreliable, too weak, and because the material of the glove rips apart so fast it makes your head spin. Also, they are ridiculously expensive and given they do not deliver anything useful other than being a gadget talking point, waste of money and time in the most comprehensive way,
Do you think the looks of a prosthetic hand are important? Would you like to have a prosthesis that resembles a human hand?
Other people do look at what they get in front of their eyes.
Seems like they - as we all - are used to "hand shaped". But opposed to what one may believe, mostly they do not obsess over whether I wear a hand or not. Actually many don't give a shit. Whether I wear the prosthetic or not, and whether I wear the hook or a hand or so, many are irritated only for a short time, then they turn away and / or chill.
In my experience, a skin like rubber appearance freaks out a lot of people. So whether it is a hand or not, the color "skin like" is really problematic. Also, permanent noise is a problem. When I shop for groceries and drop stuff a lot, that causes big problems with shop keepers. So any prosthetic that does NOT totally reliably totally grips is a total problem with anyone. That is why "bionic" or myoelectric hands are so much of a problem.
I have a number of hands. A hook, or my red PVC gloved Becker hand, so far worked well. I also have a passive prosthetic hand that I use regularly.
Would you mind having a mitten-like shaped prosthetic hand? Or a tweezer-like prosthetic hand?
It depends on what the component actually delivers in terms of performance, weight, cost, stability and grip. A tentacle, differently shaped or other functional gripper might work as well. One should discuss and design function first. Then discuss the visual aspect. Conversely, why avoid approximating the hand shape wise.
I wear hooks on a daily basis. They are shaped a bit tweezer like.
Is it important for you to be able to do precise things with your prosthetic hand? For example, writing a text message or typing?
Of course. I use my hook, or, my Becker hand, to put a thin string into the needle of my sewing machine. I also use tweezers to remove tiny splinters from the skin of my hand. I also mount appliances, devices, lamps, other things, with my body powered prosthesis. And I can do all of that also, equally well or even better, without the prosthetic arm. Particularly removal of critically small splinters is best achieved without the prosthetic. I type fast and well without prosthesis, with the hook, or with a prosthetic hand, I legally drive unmodified cars with the EXPLICIT allowance of the road traffic agency WITHOUT prosthetic arm as they agreed when I demonstrated the superior control that I have without prosthetic compared to ANY other setup. So in some applications, prosthetic arms can provide to be a relevant handicap by themselves. Really, what happens is that folks think one needs a prosthetic hand or gripper really so badly. That is not true.
Prosthetic arms - myoelectric, particularly bionic, to a very high degree, but body powered arms in a relatively less way also - are quite useless, futile and problematic to a degree, that one will learn to do mission critical precision hand work also without prosthetic. I tried a number of precise activities with the "bionic" iLimb hand; that hand performed as a total joke, not useful in the slightest way.
Like, I cook, fix fruits or veggies, I revised and changed my race bike by swapping brakes, re-tuning levers, setting gear changers, swapping other parts, without the prosthetic arm on at all. We bought, delivered, and mounted a 550 kg Ikea Pax wardrobe system, without me wearing the prosthetic at all. That is also more in terms of overall activity, than normal people do, manually.
So, it is important for me to have a lot of really serious function about myself. As long as prosthetic arms only deliver a small part of what I need, I will try to solve these problems differently. So, yes, I require and provide precision work, manually. Whether a prosthetic hand or hook is able to help remains to be seen however.
Would you prefer a ‘hard’ steel-like hand or a softer more skin-like hand?
Soft and indented hand gripper surface, or hook surfaces, have the capacity to mold their surface to any object or structure one wants to grip. So any effective grip surface will have to be deformable or plastic to at least a degree. Look at nitrile covered work gloves.
The downside is the tear up. The softer a gripper surface, the faster it wears down and the more often one will have to replace it. Underneath, however, any hand or gripper needs a hard solid structure, for work, manual work in particular. Another aspect of life is sports. It highly depends on the sport whether no prosthesis, one that delivers precise and very heavy pulls (rowing, climbing, weight lifting), elastic control of e.g. a ball, or other aspects dominate.
Yet another aspect is intimate and sex life. Here, my partner and I determine what goes and what not. But you will have to discuss this aspect with responsible adults, it is not available to minors over the internet.
What are, for you, requirements for a prosthetic arm? I mean weight, size, material, if it’s water-proof etc.
It has to be shock proof, vibration proof, sustain hammer like blows, stay on the arm and be able to pull up to 30-45 kg of weight, not cause friction rashes, control must be temperature insensitive and reliable between -20 and +35 deg C ambient temperature, it has to be easy and modular to fix or repair, wearing it long term must not cause any pressure sores, blood vessel or nerve compression or other issues; it must deliver significant grip force, allow for slip prevention with deformable grip surfaces, have a fast quick lock wrist to change or turn devices very fast, be comfortable to wear, have optimal low weight and center of gravity towards elbow not wrist, be able to totally clean it from dirt, bio hazard fluids and materials and not rust or corrode. With that it should be affordable and reasonably priced.
I have such a setup but it took us a while to get there. I run my own cable setup with ultra short hard control paths and industry parts on it, our own wrist unit that we built ourselves that is a rock solid light steel quick lock, a specialized shoulder anchor where research into that was financed by insurance, and on that arm, I wear Becker hands and Hosmer hooks for the most part. I had Centri manufacture custom colored PVC gloves for my Becker hands.
With that, I have limited but sufficient sensory feedback as to position, push and grip. With that, I am very spoiled and so far, no myoelectric arm comes close in terms of overall fluency for usage, comfort, power and reliability.
This body powered setup provides significant balance for my spine, neck, shoulders and back, PARTICULARLY for long hard repetitive stuff which is the main reason to wear it - and that is a key issue. The arm particularly helps when doing hard and repetitive works, including work, play, garden work, household cleaning, scrubbing, vacuuming, etc. - and that is where my other prosthetic arm types - myoelectric, "bionic" - ever so epically fail at a cost that is maybe 10-20 times (!) the actual cost of my body powered arm.