Optimization variables

SCONE is a software tool for predictive simulations of biomechanical movement. It uses OpenSim for modeling and simulation, and performs optimization using various control strategies, including feed-forward control, proprioceptic feedback control, and bal
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Nathan Timmers
Posts: 12
Joined: Thu Apr 04, 2019 11:10 am

Optimization variables

Post by Nathan Timmers » Tue Mar 03, 2020 3:44 am

Hi,

I was wondering how the optimization variables definition works exactly. I extracted this, as an example, from the ControllerGH2010:

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MuscleReflex {
					target = iliopsoas
					source = hamstrings
					delay = 0.005
					KL = ~-4.0<-10,10>
					L0 = ~0.85<0,2>
From the Standing High Jump tutorial I got that the optimization variable are defined like this: mean~standard deviation<minimum, maximum>. What does the ~-4.0<-10,10> and ~0.85<0,2> do then? Does it optimize the variable initializing it at either -4 or 0.85 and using the limits defined, but no standard deviation?

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Thomas Geijtenbeek
Posts: 451
Joined: Wed Mar 12, 2014 8:08 am

Re: Optimization variables

Post by Thomas Geijtenbeek » Tue Mar 03, 2020 6:43 am

Yes, well spotted! The notation is a shorthand for using a standard deviation that is a fraction (by default 10%) of the absolute value of the mean. So in the example you point out, the STD of KL = 0.4, and the STD of L0 = 0.085.

I've added some additional documentation about parameters to the SCONE website.

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Nathan Timmers
Posts: 12
Joined: Thu Apr 04, 2019 11:10 am

Re: Optimization variables

Post by Nathan Timmers » Tue Mar 03, 2020 8:48 am

Thanks for the explanation!

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