exempleSquattoSTand- Add external Load

Mouaad BOUFADNA · Post by **Mouaad BOUFADNA** » Wed Jun 03, 2020 3:21 am

Hi everyone

I am working on the SquattoStand exemple for a Master thesis project based on this movement.

I'd like to integrate in the model an external load on the body, corresponding to a barebell load.

I tried to use "problem.setControlInfo('/actuator',MocoBounds(-196.2));" to characterize the barebell weight acting on the body, but I got this error message :

"Java exception occurred:
java.lang.RuntimeException: Control info provided for nonexistent or disabled actuator '/actuator'.
Thrown at MocoProblemRep.cpp:373 in initialize().

at org.opensim.modeling.opensimMocoJNI.MocoStudy_initCasADiSolver(Native Method)

at org.opensim.modeling.MocoStudy.initCasADiSolver(MocoStudy.java:113)"

Please does someone have the solution to my problem ?

Thank you !

Nicholas Bianco · Post by **Nicholas Bianco** » Wed Jun 03, 2020 9:55 am

Hi Mouaad,

If you want to model a barbell load, the easiest approach would be to simply add a body to the model with the desired barbell mass. You don't need to use an actuator.

-Nick

Mouaad BOUFADNA · Post by **Mouaad BOUFADNA** » Thu Jun 04, 2020 3:19 am

Hi Niholas

Thank you for your answer

Should I add the barbell mass in my osim model in OpenSim with the Scale tool (body mass+ barbell mass in the Mass box) ?

Nicholas Bianco · Post by **Nicholas Bianco** » Thu Jun 04, 2020 10:02 am

Hi Mouaad,

You shouldn't use the Scale tool in this situation. Either just modify the mass parameter of the body that the barbell is "attached" to, or add a new body representing the barbell to the model (e.g., welded to the hand).

Please refer to the main OpenSim project documentation for guidance on modeling questions: https://simtk-confluence.stanford.edu:8 ... umentation.

-Nick

Mouaad BOUFADNA · Post by **Mouaad BOUFADNA** » Fri Jun 05, 2020 7:43 am

Ok sorry I didn't undertsand in that way.

I will proceed as you advice. If I have a question I will contact you again.

Thank you

Mouaad

Mouaad BOUFADNA · Post by **Mouaad BOUFADNA** » Mon Jun 15, 2020 4:24 am

Hi Nicholas

I tried to modify the mass parameter of the body to add a 20kg loading in my code like this :

Code: Select all

problem.addParameter("body_mass","body","mass",{75,95});

I got this message error :

Code: Select all

Check for missing argument or incorrect argument data type in call to function 'addParameter'.

Error in exampleSquatToStand_answers (line 58)
problem.addParameter("body_mass","body","mass",{75,95});

Should I freeze the value to add/ or the value of my body plus the load ?

Thank you

Mouaad

Christopher Dembia · Post by **Christopher Dembia** » Mon Jun 15, 2020 9:27 am

Do you intend to optimize the mass of the barbell, or do you want to use a fixed mass? You only need to use a MocoParameter (addParameter()) if you want to optimize the mass.

If you want to use a fixed mass, then directly edit the mass properties of your model.

Mouaad BOUFADNA · Post by **Mouaad BOUFADNA** » Mon Jun 15, 2020 10:01 am

Just to add a fixed barbell mass on the torso

Is there specific function to edit body properties in MocoClass ?

Something like model.updProperties("mass",value)?

Mouaad BOUFADNA · Post by **Mouaad BOUFADNA** » Mon Jun 22, 2020 8:31 am

Hi Chris

I edited my body mass in OpenSim GUI and created a new .osim file with my new mass but when I use this new model Moco isn't solving the problem after the max iterations number.

I didn't modified anything else from my previous simulation which worked well.
Should I update my solver parameters ?

I entered those ones :

Code: Select all

% Configure the solver
% ====================
solver = study.initCasADiSolver();
solver.set_num_mesh_intervals(30);
solver.set_verbosity(2);
solver.set_optim_solver('ipopt');
solver.set_optim_convergence_tolerance(1e-4);
solver.set_optim_constraint_tolerance(1e-4);
solver.set_optim_max_iterations(1000);

Mouaad BOUFADNA · Post by **Mouaad BOUFADNA** » Tue Jun 30, 2020 8:55 am

Hi Chris

I tried to edit the "2D_gait" model in the XML file with NotePad++ to add the barbell load, as explained in https://simtk-confluence.stanford.edu/d ... el+Editing

But I am not able to open it anymore in Open Sim GUI with my modificatons. When I try to use the Edit -> File command I got this message :
"Could not construct an object from the specified file"

Here the way I added the barbell to the model :

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<Body name ="barbell">
				<!--The geometry used to display the axes of this Frame.-->
					<FrameGeometry name="frame_geometry">
						<!--Path to a Component that satisfies the Socket 'frame' of type Frame.-->
						<socket_frame>..</socket_frame>
						<!--Scale factors in X, Y, Z directions respectively.-->
						<scale_factors>0.20000000000000001 0.20000000000000001 0.20000000000000001</scale_factors>
					</FrameGeometry>
                    <!--List of geometry attached to this Frame. Note, the geometry are treated as fixed to the frame and they share the transform of the frame when visualized-->
					<attached_geometry>
					<Ellipsoid name ="barbell_geom_1">
					<socket_frame>..</socket_frame>
					<radii>0.014 0.014 1.20 </radii>
					</attached_geometry>
					<!--The mass of the body (kg)-->
					<mass>8</mass>
					<!--The location (Vec3) of the mass center in the body frame.-->
					<mass_center>0 0 0</mass_center>
					<!--The elements of the inertia tensor (Vec6) as [Ixx Iyy Izz Ixy Ixz Iyz] measured about the mass_center and not the body origin.-->
					<inertia>0 0 0 0 0 0</inertia>
					<Appearance>
								<!--The opacity used to display the geometry between 0:transparent, 1:opaque.-->
								<opacity>1</opacity>
								<!--The color, (red, green, blue), [0, 1], used to display the geometry. -->
								<color>0.5 0.5 0.5</color>
							</Appearance>
			</objects>
			<groups />
		</BodySet>

With the WeldJoint (to fix the barbell to the torso) :

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<WeldJoint name="BarbellToTorso">
					<!--Path to a Component that satisfies the Socket 'parent_frame' of type PhysicalFrame (description: The parent frame for the joint.).-->
					<socket_parent_frame>torso_offset</socket_parent_frame>
					<!--Path to a Component that satisfies the Socket 'child_frame' of type PhysicalFrame (description: The child frame for the joint.).-->
					<socket_child_frame>Barbell_offset</socket_child_frame>
					<!--Physical offset frames owned by the Joint that are typically used to satisfy the owning Joint's parent and child frame connections (sockets). PhysicalOffsetFrames are often used to describe the fixed transformation from a Body's origin to another location of interest on the Body (e.g., the joint center). When the joint is deleted, so are the PhysicalOffsetFrame components in this list.-->
					<frames>
						<PhysicalOffsetFrame name="torso_offset">
							<!--The geometry used to display the axes of this Frame.-->
							<FrameGeometry name="frame_geometry">
								<!--Path to a Component that satisfies the Socket 'frame' of type Frame.-->
								<socket_frame>..</socket_frame>
								<!--Scale factors in X, Y, Z directions respectively.-->
								<scale_factors>0.20000000000000001 0.20000000000000001 0.20000000000000001</scale_factors>
							</FrameGeometry>
							<!--Path to a Component that satisfies the Socket 'parent' of type C (description: The parent frame to this frame.).-->
							<socket_parent>/bodyset/torso</socket_parent>
							<!--Translational offset (in meters) of this frame's origin from the parent frame's origin, expressed in the parent frame.-->
							<translation>0 0 0</translation>
							<!--Orientation offset (in radians) of this frame in its parent frame, expressed as a frame-fixed x-y-z rotation sequence.-->
							<orientation>0 0 0</orientation>
						</PhysicalOffsetFrame>
						<PhysicalOffsetFrame name="barbell_offset">
							<!--The geometry used to display the axes of this Frame.-->
							<FrameGeometry name="frame_geometry">
								<!--Path to a Component that satisfies the Socket 'frame' of type Frame.-->
								<socket_frame>..</socket_frame>
								<!--Scale factors in X, Y, Z directions respectively.-->
								<scale_factors>1 1 1</scale_factors>
							</FrameGeometry>
							<!--Path to a Component that satisfies the Socket 'parent' of type C (description: The parent frame to this frame.).-->
							<socket_parent>/bodyset/barbell</socket_parent>
							<!--Translational offset (in meters) of this frame's origin from the parent frame's origin, expressed in the parent frame.-->
							<translation>0 0 0</translation>
							<!--Orientation offset (in radians) of this frame in its parent frame, expressed as a frame-fixed x-y-z rotation sequence.-->
							<orientation>0 0 0</orientation>
						</PhysicalOffsetFrame>
						</frames>
				</WeldJoint>
			</objects>
			<groups />
		</JointSet>

exempleSquattoSTand- Add external Load

exempleSquattoSTand- Add external Load

Re: exempleSquattoSTand- Add external Load

Re: exempleSquattoSTand- Add external Load

Re: exempleSquattoSTand- Add external Load

Re: exempleSquattoSTand- Add external Load

Re: exempleSquattoSTand- Add external Load

Re: exempleSquattoSTand- Add external Load

Re: exempleSquattoSTand- Add external Load

Re: exempleSquattoSTand- Add external Load

Re: exempleSquattoSTand- Add external Load