Action dynamic model (was Re: Key Leads and Inertia)

[Keith Roberts]

Well put Phil. The pianist side of me thinks I obtain the proper average
keystroke for the piano after a few seconds. Then it refines as the
realization of where the action resists on the different blows comes about.
I don't believe you adjust while the note is being played, but you vary the
attack until you get the best feel of what ever subtleties the piano will
let you do. Then you go through your "bag of tricks" or the different ways
you know how to play a note and you limit yourself to the ones that work. Of
course the pianist plays a note in all of the ways you described. It is all
a reaction to what the pianist feels in the key, real or imaginary. The
input to the dynamic models would have to be real pianists until you could
refine a mechanical finger to duplicate the results from real fingers. What
came first, the chicken or the egg?
Keith Roberts

"A common mistake people make when trying to design something completely
foolproof is to underestimate the ingenuity of complete fools."   Douglas
Adams

----- Original Message -----
From: "Phillip Ford" <fordpiano@earthlink.net>
To: <pianotech@ptg.org>
Sent: Friday, May 02, 2003 9:48 AM
Subject: Action dynamic model (was Re: Key Leads and Inertia)


> > At 11:48 PM 5/1/03 , you wrote:
> >I'm not an engineer and will have to defer to those who can comment on
> this
> >in a more informed way, but your reference to the key doesn't change my
> >point.  Movement of the key is being resisted by a variety of factors the
> >would eliminate any significant effects of momentum in key travel, or so
> it
> >seems to me.
> >
> >David Love
> >davidlovepianos@earthlink.net
>
> As I see it this will be one of the problems that Stephen Birkett (or any
other contenders) faces in making a dynamic model of an action.  What input
are you going to use?  Does the player push down with constant force?  With
constant velocity?  With constant acceleration?  Does he push down with more
force initially to break the static friction and then back off to a lower fo
rce? Does he attempt to rapidly accelerate the key in the first part of the
movement and then maintain a constant velocity for the rest of the
> movement?  Etc, etc.  I'm sure you can imagine other various scenarios.
And it probably changes depending on whether the pianist is playing legato
or staccato, soft or loud, fast or slow, etc.  This information is the input
to a model, not the output from it.  The model isn't going to tell you how
the pianist is pushing down the key.  If you tell the model how the pianist
is pushing down the key it will give you some idea of how the action is
responding to the input.  So you first have to do a rather
> elaborate study to determine in what manner pianists push down keys.  Did
I hear someone say Ph.D. thesis?
>
> Phil F
>
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