add external force in matlab

[saeed aram]

hello
I want to add external force through Matlab to my model but I occur this error. what should I do?

[jimmy d]

You must successfully connect your force to a frame. The error message implies the force didn't get connected to a frame and suggests trying to call finalizeConnections() before printing your model to file.

It would be helpful if you posted the code you wrote to add the force.

[saeed aram]

You must successfully connect your force to a frame. The error message implies the force didn't get connected to a frame and suggests trying to call finalizeConnections() before printing your model to file.

It would be helpful if you posted the code you wrote to add the force.

thanks for your reply. this is my code. I didnt face any error in matlab after run this code but when I called finalizeconnections() matlab had errored.
import org.opensim.modeling.*
model = Model('gait2354_simbody.osim');
body = model.getBodySet().get('tibia_r');
force = PrescribedForce('saeed',body);
force.setForceFunctions(Constant(30), Constant(0), Constant(0));
model.addForce(force);
model.print('gait2354_simbody_withPrescribedForce.osim');

[jimmy d]

The below code seems to work for me;

Code: Select all

import org.opensim.modeling.*
model = Model('gait2354_simbody.osim');
body = model.getBodySet().get('tibia_r');
force = PrescribedForce('saeed',body);
force.setForceFunctions(Constant(30), Constant(0), Constant(0));
model.addForce(force);
model.finalizeConnections()
model.print('gait2354_simbody_withPrescribedForce.osim');

[saeed aram]

The below code seems to work for me;

Code: Select all

import org.opensim.modeling.*
model = Model('gait2354_simbody.osim');
body = model.getBodySet().get('tibia_r');
force = PrescribedForce('saeed',body);
force.setForceFunctions(Constant(30), Constant(0), Constant(0));
model.addForce(force);
model.finalizeConnections()
model.print('gait2354_simbody_withPrescribedForce.osim');

Thanks for your response. I have another question. I want to add another external force on that body(tibia_r) simultaneously. So what should I script on the above code to add this force?

[saeed aram]

The below code seems to work for me;

Code: Select all

import org.opensim.modeling.*
model = Model('gait2354_simbody.osim');
body = model.getBodySet().get('tibia_r');
force = PrescribedForce('saeed',body);
force.setForceFunctions(Constant(30), Constant(0), Constant(0));
model.addForce(force);
model.finalizeConnections()
model.print('gait2354_simbody_withPrescribedForce.osim');

would you please answer my question that how can I add another external forces simultaneously on tibia_r on different force points

[Thomas Uchida]

would you please answer my question that how can I add another external forces simultaneously on tibia_r on different force points

You can simply duplicate the code (with appropriate modifications) and specify the point of application using the setPointFunctions() method. See the following:
- Documentation for setPointFunctions(): https://simtk.org/api_docs/opensim/api_ ... 4cfdab1fbd
- Examples in testPrescribedForce.cpp: https://github.com/opensim-org/opensim- ... dForce.cpp

[saeed aram]

would you please answer my question that how can I add another external forces simultaneously on tibia_r on different force points

You can simply duplicate the code (with appropriate modifications) and specify the point of application using the setPointFunctions() method. See the following:
- Documentation for setPointFunctions(): https://simtk.org/api_docs/opensim/api_ ... 4cfdab1fbd
- Examples in testPrescribedForce.cpp: https://github.com/opensim-org/opensim- ... dForce.cpp

thank you