If the control causes the muscle to generate forces those will in general affect many or all of the accelerations in x_dot. Those are coupled so can't be calculated individually. Or were you referring only to the Jacobian of the muscle force w.r.t. the control? It's because of the way that Thelen20...

Hi All, It’s exactly three years since when I started this thread and now it is converted to a very interesting discussion. I think we all do believe providing implicit formulation can highly help us to implement optimal control techniques. Here I want to ask for a feature which can highly improve c...

Hi dear James I tried this method both in MATLAB and C++. IT works in MATLAB but not in c++, which is annoying! in my matlab script, after defining the joint angles in my defaultstate, I do this: for marker=0:11// I have 12 markers markerSet.get(marker).changeBodyPreserveLocation(defaultstate,model....

Thanks James, that was a nice trick and in solved the problem!
Sina

Hi, I was wondering if there is any function to calculate position of a point relative to the ground assuming a known set of joint angles? I am an API user and I am using HuntCrossley contact forces. I need to calculate the position of the spheres respect to the ground(half space) within my script. ...

Hi all I am trying to report fiber active and passive forces using matlab API. Here is my code: % load model osimModel = Model('test.osim'); % initiate states and set proper values defaultStates = osimModel.initSystem(); ... % geting the fiber force fiberForce = muscle.getFiberForce(defaultStates) B...

if you only need pos, vel and acc of COM then I would say it's easier and much faster to calculate them analytically. You have a simple linkage and you can easily drive the analytic equations for pos,vel and acc of COM using syms toolbox in MATLAB. You can find the method in any basic robotics book.

Hi everyone I am facing the same problem and it's interesting that this old post does not have any replies! I was wondering how does BodyKinematic calculates the position, velocity and acceleration of the COM. I ran BodyKinematic analysis on two different models, one with a proper foot-ground contac...

Thanks dear Ayman.

Hi every one I am trying to create a PiecewiseConstantFunction within a Matlab script: PiecewiseConstantFunction(nNodes, tVec, U) where nNodes is an integer and tVec&U are two vectors (size = 1xnNodes) When I run my script, it returns this error: ??? No constructor 'org.opensim.modeling.PiecewiseCon...