To Biomech-L members

I've posed to you this question some days ago:

>I'm a phd student and I'm working on human finger movement simulation:
>Using a simple finger model (3 rods, 3 hinges) I've move the finger
>following two different principles:
>1) the minimum angular displacement
>2) the minimum cartesian jerk on the fingertip position
>I've noted different results on angular dispositions during movement.
> >From a physiologic point of view (on your experiences) which is the
>hypothesis that grant a more natural movement (and natural movement
>means also long life of muscles?): no. 1 or no. 2? Please on your
>answer consider your experience and not literature tendency
>Thanks for your attention and possible answer,
> Emanuele Lindo

I report the answer of D. Kamper to my question (perhaps I've lost some
other answers, sorry for my careless behavior):

Hi Emanuele,

First, I would say that there is less redundancy in the system
than one might expect, because of limits in joint range of motion
and coupling between the joints, especially DIP with PIP and MCP.
That stated, Biggs and Horch found better correlation between
muscle lengths and fingertip location than muscle lengths and
joint angles, so you might want to focus on fingertip location:

Biggs J, Horch K, Clark FJ. Extrinsic muscles of the hand signal
fingertip location more precisely than they signal the angles of
individual finger joints. Exp Brain Res 1999; 125: 221-230.


Thanks for your attention and for D. Kamper suggestion,

Emanuele Lindo


Secco Emanuele Lindo
Dip. Informatica e Sistemistica
UniversitÓ di Pavia
Via Ferrata, 1 - 27100 Pavia - Italia
cell. +39 (0)347
tel. +39 (0)382 50.53.52
fax. +39 (0)382 50.53.73

"What is the formula for the journey to the ultimate meaning of reality?

Living the real.
The only condition for being truly and faithfully religious is
to live always the real intensely, without negating or forgetting

(The Religious Sense, McGill-Queen's University Press, 1997, p. 108)

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