Does anybody know what the activation1, activation2, and damping in the Schutte 1993 Muscle model are?
What are their units?
I would like to know how they are calculated.
I've read some papers regarding the model. I could not figure them out, yet.
Please help me out.
Jae Kim
Parameters( activation1,activation2,damping)?
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Jae-Woong Kim
- Posts: 1
- Joined: Fri Feb 24, 2012 11:50 am
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Edith Arnold
- Posts: 44
- Joined: Fri Apr 06, 2007 2:07 pm
Re: Parameters( activation1,activation2,damping)?
Hi Jae,
The best source for the theory behind the Schutte muscle model is Lisa Schutte's dissertation, appendices 2 and 3.
Using musculoskeletal models to explore strategies for improving performance in electrical stimulation-induced leg cycle ergometry
LM Schutte - 1992 - Stanford University
According to the that text, activation1 and activation2 (k1 and k2) relate to the activation and deactivation time constants (t_act and t_deact)
t_act = 1/(k1+k2)
t_deact = 1/k2
Damping relates to the force velocity curve. In this two state, massless muscle model the force-velocity curve is inverted to find fiber velocity from tendon force. The physiological force-velocity curve has regions where the slope is zero, so there is a singularity in its inverse.
To get around this, a damping element is added in parallel to the active contractile element. According to page 118 of the Schutte's dissertation
Instructions for getting copies of Stanford dissertations are here:
http://library.stanford.edu/depts/ssrg/ ... tions.html
From a practical standpoint, when I was experimenting with the properties of different muscle models, I made a simple test case based on the API tug of war example. I made a couple different types of muscles with the same geometry and architecture parameters and gave them the same control inputs. This was a useful exercise for getting an intuitive sense of how each parameter affected the results.
-Edith
The best source for the theory behind the Schutte muscle model is Lisa Schutte's dissertation, appendices 2 and 3.
Using musculoskeletal models to explore strategies for improving performance in electrical stimulation-induced leg cycle ergometry
LM Schutte - 1992 - Stanford University
According to the that text, activation1 and activation2 (k1 and k2) relate to the activation and deactivation time constants (t_act and t_deact)
t_act = 1/(k1+k2)
t_deact = 1/k2
Damping relates to the force velocity curve. In this two state, massless muscle model the force-velocity curve is inverted to find fiber velocity from tendon force. The physiological force-velocity curve has regions where the slope is zero, so there is a singularity in its inverse.
To get around this, a damping element is added in parallel to the active contractile element. According to page 118 of the Schutte's dissertation
Figure A.3.4 gives a nice graphical representation of what that means for the force-velocity curve.The result [of the damping element] is that when the activation is zero or the muscle fibers are very long or very short, the force velocity relationship is described by f = b_m*v_m which is invertible rather than by f = 0*v_m which is not
Instructions for getting copies of Stanford dissertations are here:
http://library.stanford.edu/depts/ssrg/ ... tions.html
From a practical standpoint, when I was experimenting with the properties of different muscle models, I made a simple test case based on the API tug of war example. I made a couple different types of muscles with the same geometry and architecture parameters and gave them the same control inputs. This was a useful exercise for getting an intuitive sense of how each parameter affected the results.
-Edith