Search found 99 matches

by Sina Porsa
Mon Jun 04, 2012 6:49 pm
Forum: OpenSim
Topic: Define the initial muscle states for FD (API)
Replies: 5
Views: 603

Re: Define the initial muscle states for FD (API)

Hi Ayman Thanks for your help. I have another strange problem. I changed my code to this: const Set<Actuator>& actuatorSet = osimModel.getActuators(); ActivationFiberLengthMuscle* muscle1 = dynamic_cast<ActivationFiberLengthMuscle*>( &actuatorSet.get(0) ); ActivationFiberLengthMuscle* muscle2 = dyna...
by Sina Porsa
Sun Jun 03, 2012 10:35 pm
Forum: OpenSim
Topic: Define the initial muscle states for FD (API)
Replies: 5
Views: 603

Define the initial muscle states for FD (API)

Hi all; I am trying to load an existing osim file to perform a forward dynamic. But I cannot initiate the muscle states (activation and fiber length). The model has 2 Thelen muscles. Here is my code: ///////////////////////// // Load the Osim model // ///////////////////////// Model osimModel ("twoM...
by Sina Porsa
Wed Apr 25, 2012 8:33 pm
Forum: OpenSim
Topic: Some problems with tugOfWar example
Replies: 8
Views: 1003

Re: Some problems with tugOfWar example

Hi Ajay and Romain, sorry for my late reply. Thanks, it works now. The problem was the missed line as Ajay mentioned. I just understood that the same line is missing in the API example file in opensim directory. (c:\OpenSim2.4.0\sdk\APIExamples\ExampleMain\TugOfWar_Complete.cpp) It would be great if...
by Sina Porsa
Mon Feb 13, 2012 8:56 pm
Forum: OpenSim
Topic: Some problems with tugOfWar example
Replies: 8
Views: 1003

Re: Some problems with tugOfWar example

Hi Ayman, I do still have problem with the tugOfWar example. In the "developers guide - section 2.16" we define two linear functions for each of the muscles. I compiled and ran the code and loaded the results in the GUI. I expected linear activation in the muscles, but as you can see in the attached...
by Sina Porsa
Tue Jan 03, 2012 5:00 pm
Forum: OpenSim
Topic: Some problems with tugOfWar example
Replies: 8
Views: 1003

Re: Some problems with tugOfWar example

Hi Ayman,
according to the code, I expect piece-wise linear excitation/activation for muscles. I have attached the activation plots which is not linear. The activatoin initiates at its initial value and decreases by time.
Cheers,
Sina.
by Sina Porsa
Tue Dec 20, 2011 7:11 pm
Forum: OpenSim
Topic: Some problems with tugOfWar example
Replies: 8
Views: 1003

Some problems with tugOfWar example

Hi, I am trying to compile the tugOfWar example in the "OpenSim Developers Guide" step by step. I want to modify step 15 (which uses some functions to make the muscle control history at page 34) and replace the LinearFunction with PiecewiseLinearFunction. So I replaced this piece of code: Prescribed...
by Sina Porsa
Mon Nov 28, 2011 9:56 pm
Forum: OpenSim
Topic: How does static opt. incorporate force-velocity function?
Replies: 0
Views: 166

How does static opt. incorporate force-velocity function?

Hi all,
I was wondering how does static optimization account for force-velocity and force-length properties of muscle? As I have to type some equations to explain my question, please take a look at the attached file
Document1.pdf
(172.66 KiB) Downloaded 65 times
by Sina Porsa
Mon Nov 28, 2011 4:53 pm
Forum: OpenSim
Topic: Zeroing Muscle Activation
Replies: 4
Views: 1509

Re: Zeroing Muscle Activation

Hi Craig According to your post: "The solve for equilibrium actuator states solves for the muscle fiber length state values so that that they are in equilibrium with their tendon." Does it mean (Muscle active force + muscle passive force)*cos(pennation angle) = (tendon elastic force) I still cannot ...
by Sina Porsa
Sun Oct 23, 2011 4:57 pm
Forum: OpenSim
Topic: Hertz stiffness and Hunt and Crossley dissipation
Replies: 3
Views: 755

Re: Hertz stiffness and Hunt and Crossley dissipation

Hi Sherm Thanks for your reply, it was really helpful. I have one other question about the mentioned paper. The paper indicates that a variety of numerical integrators are available for forward dynamics. But I do not know how should I implement these integrators in "ForwardTool" <ForwardTool> <model...
by Sina Porsa
Thu Oct 20, 2011 5:01 pm
Forum: OpenSim
Topic: Hertz stiffness and Hunt and Crossley dissipation
Replies: 3
Views: 755

Hertz stiffness and Hunt and Crossley dissipation

Hi All, According to this paper, in order to define a contact between two bodies I need elastic modulus and dissipation coefficients of each of the bodies(4 parameters): http://www.stanford.edu/group/nmbl/publications/pdf/Sherm2011.pdf but in the *.osim file, I can only define 2 parameters including...