Update prescribed force

[Ana de Sousa]

Hello, if anyone could help me with this topic.

I am able to create this force (at the model), but I do not know how I change it in Matlab, during forward simulation

Code: Select all

% Create force
pelvis_Force = PrescribedForce(pelvis);

pelvis_Force.setName('pelvis_force');
pelvis_Force.setForceFunctions(Constant(0), Constant(250), Constant(0));

% Add the force to the model
osimModel.addForce(pelvis_Force); % Add the force to the model

How can I get this pelvis_Force and change its ForceFunction during simulation?

[jimmy d]

You would be better off to use ExternalForce(). You would create a time history of the force vector and location then add that to add it to the model.

[Ana de Sousa]

Thanks for the response.
So, is it a prescribed force? Is there a way to make it dependable to another variable? In a way that I could change it dynamically? (similarly to the way that we can do to a torque in a joint)

[jimmy d]

So, is it a prescribed force?

No, it is an external force. They are different. I suggested that because you can assign the location of the point over time. However, I do see now that PrescribedForce() has a method for assigning a pointFunction(), so you just need to define the function you want for location over time.

[Ana de Sousa]

Both options (prescribed and external) are only defined by functions over time?
Is there a way to make it defined over another variable, for example?

For example, something like "if the knee joint is higher than 45 deg, force = 10, otherwise force = 0"?