While I am still busy lining up comparative benchmark type manipulations to compare iLimb and cable controlled prosthetics and considering artistic aspects of prosthetics, the new 2010 model of Otto Bock’s Michelangelo hand apparently featuring ‘biomimicry’ (i.e., their version of the iLimb) can be seen already on video. More recently seen, the OT Leipzig 2010 version looks disappointing in comparison. Probably we see the same phenomenon as in the car industry: gorgeous concept cars or advertising prosthesis – and no thrill afterwards. I also attended a local live demo in May 2011 that seemed to subdue too exuberant initial expectations.
In trying to be ‘bionic’ (whatever the precise definition of that term may be), there are also other interesting projects such as the RAPHaEL hand or works done with Alejandro Hernandez Arieta at the AI Lab of the University of Zuerich. Related products seem to be the DEKA arm and the iLimb and the very similar looking BeBionic hand. Currently, research and development works towards multifinger and complex motion control rather than the two-electrode control that myoelectric hands have since the fifties.
The iLimb, BeBionic and Michelangelo hand:
- are not at all thought-controlled (as awkward advertising hype may suggest)
- look cool, but obviously any hand can be tweaked to also look cool
- are restricted to myoelectric arms / sockets
- only use two electrodes (open/close/switch) rather than currently emerging complex control paradigms
- may deplete batteries rather quickly
- are extremely/prohibitively expensive
- offer limited grasp/lift options
- seem to have significant delay (as other myoelectric arms)
- emit irritating motor hissing sounds and are really noisy and loud
- do not look good with cosmetic gloves on
Now, what immediately catches my eye in the Michelangelo hand videos is what appears to me to be a rather significant time lag between the moment a grip or hand movement seems to be in order and until it is actually done. I have started to investigate the subject of myoelectric prostheses and time lags a bit further even though maybe one day we will see mind control. It appears that these time lags are inherent to myoelectric control and so cable control wins.
Yes, of course – mind control! – “Only once I can use mind control, why the clumsy interface?” (Wolf Schweitzer, commenting on the Michelangelo hand, 2009)
As the Michelangelo hand is neither available, nor guaranteed to be affordable at all, nor is there any indication that it will work comfortably on a rather long stump such as mine given my problems I had so far using myoelectric technology I decided that a responsive and fast, sufficiently complex and cool hand does not necessarily have to be electric. Au contraire :-)
Meet my Becker Lock Grip Hand. It features an adaptive grip, particularly precise cable control, full manufacturer warranty and the option of getting a custom model made – also I went artistic with it and turned it into another Red Hand. It even solves difficult gripping problems that are probably way beyond these very modern gadgets. See my benchmark demos for handling eggs or picking grapes. This must be the ultimate proficiency test.
Copyright Otto Bock.
For the Michelangelo hand I sure hope for a good robustness and behavior towards wet environment, and fast silent function in a convincing way. The effective performance of the Michelangelo hand will be extremely good, if one was to take the product name ‘Michelangelo‘ serious. Conversely, you may well think that naming a prosthetic hand ‘Michelangelo’ could be blasphemous as the Italian painter Michelangelo was famous for his painting ‘The Hand of God’ but I could not possibly comment. Let us wait for the final product.
The potential is good; if that hand is built to carry, push or pull about 15 to 25 kg (as long as the socket is up for that), if it withstands fluid and if it can be user-programmed for more sophisticated functions and picks up more than just two electrodes (my myoplasty on the arm stump should allow me to wiggle more than just two muscle packs), and if the price is reasonable in relation to a responsible function – then I can see this going in an extremely promising direction.
The control seems to be under construction at the Bernstein Focus Neurotechnology Göttingen in Goettingen:3b – Control of multi-joint multi-sensor hand prostheses, J. Michael Herrmann, Armin Biess, Florentin Wörgötter, and Otto Bock HealthCare GmbH; the project is devoted to the robust and efficient signal analysis of myoelectric data obtained from non-invasive electrode arrays. The goal of the project is the control of prostheses with multiple degrees of freedom and additional sensors based on this data analysis, such that it achieves a flexibility that compares to natural movements. – Advanced prosthetic devices for the upper extremities are usually controlled by myoelectric signals derived from residual or still available muscles. However, conventional transcutaneous recording of movement activity is quite limited in terms of the degrees of freedom that can be controlled reliably and simultaneously. Advances in signal processing and nerve transfer surgery (Kuiken et al. 2007) have considerably improved the achievable signal quality, which now enables some amputees to benefit from recent developments of prosthetic hands. For example, the Michelangelo hand provides proportional control for multi-axial movements, but a complexity reduction had to be achieved by controlling movement synergies rather than the individual degrees of freedom. Even if high-bandwidth signal transduction from the subject to the device is in sight, the information flow in the reverse direction will retain severe limitations. In order to exploit recent advances in robotics in prosthetic devices appropriate feedback signals must be reconstructed from an optimal combination of local sensors and efficient data analysis.
According to a press release, in Madrid, Spain, the first transplant of the Otto Bock MichelAngelo Bionic Hand has been completed. Axel Eichinger, a 28-year-old born without a right hand, said that he has gained self-esteem from the transplant and although it took a while to adjust, he now uses his new hand with ease. It took four weeks for Eichinger to learn to use his new hand, which is a skeleton made from stainless steel and aluminum with a soft skin-like covering. The Otto Bock MichelAngelo bionic hand will be available next year in Spain and throughout the world by spring 2010.
To that I have to add that probably any well constructed and cool looking prosthetic arm will help to build self esteem. And at a whopping 70’000 to 100’000 CHF I can see myself gaining self esteem from return on investment rather than spending all that on a prosthetic arm.