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Posted: **Thu Aug 20, 2020 9:30 am**

Dear Experts

To practice the IAA tool, I added these lines to AnalysisSet:

<InducedAccelerations name="InducedAccelerations">
	<on>true</on>
	<start_time>0</start_time>
	<end_time>5</end_time>
	<step_interval>10</step_interval>
	<in_degrees>true</in_degrees>
	<coordinate_names> All</coordinate_names>
	<body_names> center_of_mass</body_names>
	<ConstraintSet name="constraintset">
		<objects>
			<RollingOnSurfaceConstraint name="right_foot_contact">
				<isEnforced>false</isEnforced>
				<socket_rolling_body>/bodyset/calcn_r</socket_rolling_body>
				<socket_surface_body>/ground</socket_surface_body>
				<surface_normal>0 1 0</surface_normal>
				<surface_height>0</surface_height>
				<friction_coefficient>0.75</friction_coefficient>
				<contact_radius>0.01</contact_radius>
			</RollingOnSurfaceConstraint>
			<RollingOnSurfaceConstraint name="left_foot_contact">
				<isEnforced>false</isEnforced>
				<socket_rolling_body>/bodyset/calcn_r</socket_rolling_body>
				<socket_surface_body>/ground</socket_surface_body>
				<surface_normal>0 1 0</surface_normal>
				<surface_height>0</surface_height>
				<friction_coefficient>0.75</friction_coefficient>
				<contact_radius>0.01</contact_radius>
			</RollingOnSurfaceConstraint>
		</objects>
	</ConstraintSet>
	<force_threshold>6</force_threshold>
	<compute_potentials_only>false</compute_potentials_only>
	<report_constraint_reactions>true</report_constraint_reactions>
</InducedAccelerations>

The first issue is that although the "socket_rolling_body" is set to "/bodyset/calcn_r" and the nex to "/ground", but when I load the setup file in Analyze tool, these two arguments become empty and I have to write the "calcn_r" and "ground" again.

The second issue is that this error apears:

Performing Induced Accelerations Analysis
time = 0.73
time = 0.733192
time = 0.737745
time = 0.740851
time = 0.745007
External force expressedInBody ground not found.
Exception:
ArrayPtrs.get: Array index out of bounds.

I was reading in the forum that changing the "ground" to the contact segment (e.g calcn_X) in the Eternal_loads.XML file can fix the issue:

<force_expressed_in_body>calcn_r</force_expressed_in_body>
<point_expressed_in_body>calcn_r</point_expressed_in_body>

And the IAA ran successfully without any error.
Is this a right way? If I want to use pipline, I have to create two External_load files, one for ID, RRA and CMC and one IAA.

I wonder if anyone would helm me to fix these two issue.

Your help is much appreciated.

Regards,
Mohammadreza

Posted: **Thu Sep 26, 2024 11:52 pm**

Hello Mohammadreza, I'm getting the same behavior in OpenSim 4.4.

It is definitely a bug. When I load the .xml, the IAA field is changed, clearing the information about the bodies in RollingOnSurfaceConstraint.

: errorIAA.png (151.94 KiB) Viewed 406 times

And it happens as well if you load the .xml file using the API in Python. I manage to update the values using this piece of code:

Code: Select all

iaa = analise2.getAnalysisSet().get(0)
CS = iaa.getPropertyByName('ConstraintSet')
CSo = CS.getValueAsObject()
CS_obj = CSo.getPropertyByIndex(1) # <objects>
constraintR = CS_obj.updValueAsObject(0) #<RollingOnSurface ... >
constraintL = CS_obj.updValueAsObject(1) #<RollingOnSurface ... >
propriedade = constraintR.updPropertyByName('socket_rolling_body')
osim.PropertyHelper.setValueString('/bodyset/calcn_r', propriedade)
propriedade = constraintR.updPropertyByName('socket_surface_body')
osim.PropertyHelper.setValueString('/ground', propriedade)

propriedade = constraintL.updPropertyByName('socket_rolling_body')
osim.PropertyHelper.setValueString('/bodyset/calcn_l', propriedade)
propriedade = constraintL.updPropertyByName('socket_surface_body')
osim.PropertyHelper.setValueString('/ground', propriedade)

And the External Forces File can be generated using the options here: https://github.com/opensim-org/opensim-core/issues/2076

But that is not all... When I run the AnalyzeTool, it complains that the State was not loaded. I load the State and it complains that the it has different states number compared to the loaded model...

Any help would be wonderful, since using the GUI is still a limitation with this bug.

Best regards.

Posted: **Fri Sep 27, 2024 1:31 am**

UPDATE,

To make it clearer:

Code: Select all

analise3 = osim.AnalyzeTool('analise.xml')

iaa = analise3.getAnalysisSet().get(0)
CS = iaa.updPropertyByName('ConstraintSet')
CSo = CS.updValueAsObject()
CS_obj = CSo.updPropertyByIndex(1) # <objects>
constraintR = CS_obj.updValueAsObject(0) #<RollingOnSurface ... >
constraintL = CS_obj.updValueAsObject(1) #<RollingOnSurface ... >
propriedade = constraintR.updPropertyByName('socket_rolling_body')
osim.PropertyHelper.setValueString('/bodyset/calcn_r', propriedade)
propriedade = constraintR.updPropertyByName('socket_surface_body')
osim.PropertyHelper.setValueString('/ground', propriedade)

propriedade = constraintL.updPropertyByName('socket_rolling_body')
osim.PropertyHelper.setValueString('/bodyset/calcn_l', propriedade)
propriedade = constraintL.updPropertyByName('socket_surface_body')
osim.PropertyHelper.setValueString('/ground', propriedade)

analise3.verifyControlsStates() ## ok, i passes

analise3.run() # fails

Code: Select all

---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
Input In [14], in <cell line: 1>()
----> 1 analise3.run()

File c:\Users\Carlo\.conda\envs\opensim44\lib\site-packages\opensim\tools.py:3902, in AnalyzeTool.run(self, *args)
   3901 def run(self, *args) -> "bool":
-> 3902     return _tools.AnalyzeTool_run(self, *args)

RuntimeError: std::exception in 'bool OpenSim::AnalyzeTool::run()': Failed to connect Socket 'rolling_body' of type PhysicalFrame (details: Connectee for Socket 'rolling_body' of type PhysicalFrame in RollingOnSurfaceConstraint at /constraintset/right_foot_contact is unspecified. If this model was built programmatically, perhaps finalizeConnections() was not called before printing.
	Thrown at Component.h:3383 in finalizeConnection().).
	In Object 'right_foot_contact' of type RollingOnSurfaceConstraint.
	Thrown at Component.cpp:313 in finalizeConnections().

The thing is that I specify the PhysicalFrame in both XML and in the code above...

socorro.xml: (8.7 KiB) Downloaded 15 times

Posted: **Fri Sep 27, 2024 7:03 am**

UPDATE,

I took a leap of faith and tested in OpenSim 4.5, but I got the same behavior in OpenSim GUI.

Best regards.

Posted: **Fri Sep 27, 2024 1:00 pm**

Hi, I just tested IAA using the dataset and setup files available here (https://simtk.org/projects/nmbl_running).
I confirm that after loading the setup file in the GUI, both socket_rolling_body and socket_surface_body fields are empty (the tool doesn't get those parameters from the XML file), and the error appears. If I specify these parameters manually in the GUI, then it works. This is very likely a bug. I suggest you open an Issue on the opensim-core GitHub page: https://github.com/opensim-org/opensim-core/issues

Posted: **Mon Sep 30, 2024 1:40 pm**

Thanks, Mohammadreza!

Has anyone tried creating the configuration of the InducedAcceleration component with code?

Best regards.

simtk.org

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