View Full Version : Relation between Joint Torque, Moment Arm, and muscle forces

Sindharta Tanuwijaya
10-09-2005, 01:08 PM

Thank you for some people who gave me some comments
and resources the other day, and it seems I would need
to do some experiments to determine which moment arm
calculation method would be the most appropriate for
my program.

Anyway, I would like to ask about the relationship
between joint torque, moment arm, and muscle forces.
>From "Creating and retargetting motion by the
musculoskeletal human body model" by Komura et al.,
the relationship is defined as
"the torque of joint i is the sum of the cross product
of the moment arm and the force of each muscle
crossing that joint", or

torque(i) = sigma(r(j) X f(j))

r: moment arm
f: muscle force

If I want to find the moment arm and muscle force
based on the torque as input, I think it will generate
underdetermined equations (written on that paper too).
I wonder if anyone has a solution or comments for that
? Perhaps on the relationship itself?

Thank you in advance,

Sindharta T.

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