Pete14 Surely, the lab tests will answer all our questions, but still, kudos to the creator; and if this system proves itself on the field, I might just change my mind about getting an acoustic, for you see, a’ tunin’ every six months is the acoustic’s achilles heel (and perhaps also price, size, loudness, etc; but still, this could be a -big- step in the right direction).
If calling the tuner is your main complain about acoustic pianos (Pete!!! I don't recognize you anymore!!!) actually a Dampp-Chaser combined humidifier/dehumidifier will achieve similar results. I used to tune my piano every 6 months, after switching to an instrument with a Dampp-Chaser, I'm now every two years and only because I force myself to call the technician, neither I nor my daughters hear any out-of-tuness.
Now, with that said, I still see value in this prototype, for example because one could change temperament (not at will! that would be too much of a difference and switching something dramatic too often could damage the instrument!! but between similar enough temperaments it can be done) or do minor "touch up" of the tuning, or minor pitch raises of the whole instrument, and all sort of stuff. @Don I suggest looking into these "value added" functionalities rather than just the basic tuning which frankly (as an acoustic piano owner) never was a chore or an excessive expenditure for me, nor is for any of the acoustic piano owners I know.
Finally, I understand this is a prototype (I build lots of prototypes myself), but I would like to stress it: in its current "look", I would never install it on my piano (a M&H 6' AA, for what is worth). Another huge concern would be to drill the frame, both cosmetically and structurally. I'd never allow that on my acoustic piano (well, perhaps "never" is too strong, let me say "only if offered a warranty that if the frame ever cracks I get immediately a cash value of the cost of purchasing new the same model I have", which I suspect it's an unreasonable warranty to ask ). But even if everything is proved perfect and I were offered it for free, I'd never install it in its current look. So I recommend you work hard on the look too.
@Don don't take me wrong. I'm not doing another "armchair complain", and perhaps I'm saying things which you have already carefully thought (but I did not see mention of them in the video). I'm just saying what lots of acoustic piano owners would say. Perhaps the best approach for you would be to work with a piano manufacturer rather than as retrofit. I can see that being integrated into the design of the piano from before it's manufactured, your invention can easily be very clean-looking, not requiring structurally-arguable changes of the instrument, and perhaps have a few more options in the design which you are forced to not explore if you are limiting yourself to retrofits.
If you haven't already, I suggest that you contact http://www.hurstwoodfarmpianos.co.uk/ or perhaps Steingraeber who are the only two piano manufacturers open to do seriously advanced stuff and are not stuck in the past (or at most doing very minor changes) like all others.
Best of luck
: You can tell "a mechanical engineer has vouched this as structurally sound", but who's gonna guarantee that the hole is drilled correctly? what if the cast iron has been cured incorrectly and has inner stress which is released by drilling the hole and causes a crack? A crack in the frame makes the piano basically worthless and it's too high of a risk.