Elastic Foundation model

[Krishnakumar Sankar]

Hi
I would like to know about Elastic foundation forces method to execute a grasp activity of a glass.

1.What type of mesh I should create for the object.

2.Should the mesh be created on the finger segments too ? .

3.For understanding,could you post a sample html code for elastic foundation model


Thank you

[jimmy d]

1.What type of mesh I should create for the object.

Isn't that a question for you to answer? What type of mesh should you create to answer your research question?

2.Should the mesh be created on the finger segments too ?

Do you want to compute forces between the fingers and the glass? If so, it sounds like you do need contact at the fingers

3.For understanding,could you post a sample html code for elastic foundation model

There is documentation for elastic foundation force here;
https://simtk.org/api_docs/opensim/api_ ... ml#details

There is a community tutorial here;
https://simtk.org/projects/contact_osim_u

[Krishnakumar Sankar]

Do you want to compute forces between the fingers and the glass? If so, it sounds like you do need contact at the fingers

The finger segments are in .vtp file format.What is the procedure to mesh it.I mean how to convert to a 3D read/write file format.

[Thomas Uchida]

The finger segments are in .vtp file format.What is the procedure to mesh it.I mean how to convert to a 3D read/write file format.

I searched the Forum for "vtk" and found this topic, which looks promising: viewtopicPhpbb.php?f=91&t=2946

[Krishnakumar Sankar]

Thank you so much sir.

[Krishnakumar Sankar]

Hi , My objective is to obtain the joint moments of the fingers for the grasp activity of a glass tumbler.

To implement elastic foundation,firstly I triangular meshed the finger segments and the glass .

Created contact spheres on the glass in such a way that the contact spheres of the finger segments to come in contact with the spheres of the glass.

Then I performed the simulation using inverse dynamics method.No matter what ever changes i do in stiffness constant or the position of the contact spheres,the moment values remain the same as it was when i performed the simulation at the first instant.What am i missing.

Could you please help me out.

Below is a piece of the code for your look

Code: Select all

<ElasticFoundationForce name="Ggrasp_MCP4">
					<!--Flag indicating whether the force is disabled or not. Disabled means that the force is not active in subsequent dynamics realizations.-->
					<isDisabled>false</isDisabled>
					<!--Material properties.-->
					<ElasticFoundationForce::ContactParametersSet name="contact_parameters">
						<objects>
							<ElasticFoundationForce::ContactParameters>
								<!--Names of geometry objects affected by these parameters.-->
								<geometry>glass10 Iphal10</geometry>
								<stiffness>63000000</stiffness>
								<dissipation>0.2</dissipation>
								<static_friction>0.2</static_friction>
								<dynamic_friction>0.2</dynamic_friction>
								<viscous_friction>0.3</viscous_friction>
							</ElasticFoundationForce::ContactParameters>
						</objects>
						<groups />
					</ElasticFoundationForce::ContactParametersSet>
					<!--Slip velocity (creep) at which peak static friction occurs.-->
					<transition_velocity>0.1</transition_velocity>
				</ElasticFoundationForce>
                         <ContactSphere name="glass10">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>-0.0035 0.036 0.022</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.007</radius>
				</ContactSphere>
<ContactSphere name="Iphal10">
					<!--Body name to connect the contact geometry to-->
					<body_name>Iphalanx10</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.003 -0.02 -0.0045</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.007</radius>
				</ContactSphere> 

[jimmy d]

You haven't told us anything about how you are doing the analysis. Are you doing this in ID, Static Optimization, CMC?

Where are you getting the measured moments from? Can you include pictures of the model and simulation?

just posting your xml code for the component tells us little.

[Krishnakumar Sankar]

You haven't told us anything about how you are doing the analysis. Are you doing this in ID, Static Optimization, CMC?

i am performing Inverse dynamics analysis.

Glass 4,6.mot

(1.66 KiB) Downloaded 68 times

Glass and the hand with contact spheres on their surface.

Fig1.JPG (19.19 KiB) Viewed 1716 times

Graph for MCP joint moments

Capture.JPG (60.42 KiB) Viewed 1716 times

Considering both the hand segments and the glass as rigid bodies,I have performed elastic foundation force methodology.

Code: Select all

<ElasticFoundationForce name="Ggrasp_MCP4">
					<!--Flag indicating whether the force is disabled or not. Disabled means that the force is not active in subsequent dynamics realizations.-->
					<isDisabled>false</isDisabled>
					<!--Material properties.-->
					<ElasticFoundationForce::ContactParametersSet name="contact_parameters">
						<objects>
							<ElasticFoundationForce::ContactParameters>
								<!--Names of geometry objects affected by these parameters.-->
								<geometry>glass1 Iphal1</geometry>
								<stiffness>63000000</stiffness>
								<dissipation>0.2</dissipation>
								<static_friction>0.2</static_friction>
								<dynamic_friction>0.2</dynamic_friction>
								<viscous_friction>0.3</viscous_friction>
							</ElasticFoundationForce::ContactParameters>
						</objects>
						<groups />
					</ElasticFoundationForce::ContactParametersSet>
					<!--Slip velocity (creep) at which peak static friction occurs.-->
					<transition_velocity>0.1</transition_velocity>
				</ElasticFoundationForce>
				<ElasticFoundationForce name="Ggrasp_MCP4">
					<!--Flag indicating whether the force is disabled or not. Disabled means that the force is not active in subsequent dynamics realizations.-->
					<isDisabled>false</isDisabled>
					<!--Material properties.-->
					<ElasticFoundationForce::ContactParametersSet name="contact_parameters">
						<objects>
							<ElasticFoundationForce::ContactParameters>
								<!--Names of geometry objects affected by these parameters.-->
								<geometry>glass2 Iphal2</geometry>
								<stiffness>63000000</stiffness>
								<dissipation>0.2</dissipation>
								<static_friction>0.2</static_friction>
								<dynamic_friction>0.2</dynamic_friction>
								<viscous_friction>0.3</viscous_friction>
							</ElasticFoundationForce::ContactParameters>
						</objects>
						<groups />
					</ElasticFoundationForce::ContactParametersSet>
					<!--Slip velocity (creep) at which peak static friction occurs.-->
					<transition_velocity>0.1</transition_velocity>
				</ElasticFoundationForce>
				<ElasticFoundationForce name="Ggrasp_MCP4">
					<!--Flag indicating whether the force is disabled or not. Disabled means that the force is not active in subsequent dynamics realizations.-->
					<isDisabled>false</isDisabled>
					<!--Material properties.-->
					<ElasticFoundationForce::ContactParametersSet name="contact_parameters">
						<objects>
							<ElasticFoundationForce::ContactParameters>
								<!--Names of geometry objects affected by these parameters.-->
								<geometry>glass3 Iphal3</geometry>
								<stiffness>63000000</stiffness>
								<dissipation>0.2</dissipation>
								<static_friction>0.2</static_friction>
								<dynamic_friction>0.2</dynamic_friction>
								<viscous_friction>0.3</viscous_friction>
							</ElasticFoundationForce::ContactParameters>
						</objects>
						<groups />
					</ElasticFoundationForce::ContactParametersSet>
					<!--Slip velocity (creep) at which peak static friction occurs.-->
					<transition_velocity>0.1</transition_velocity>
				</ElasticFoundationForce>
				<ElasticFoundationForce name="Ggrasp_MCP4">
					<!--Flag indicating whether the force is disabled or not. Disabled means that the force is not active in subsequent dynamics realizations.-->
					<isDisabled>false</isDisabled>
					<!--Material properties.-->
					<ElasticFoundationForce::ContactParametersSet name="contact_parameters">
						<objects>
							<ElasticFoundationForce::ContactParameters>
								<!--Names of geometry objects affected by these parameters.-->
								<geometry>glass5 Iphal5</geometry>
								<stiffness>63000000</stiffness>
								<dissipation>0.2</dissipation>
								<static_friction>1</static_friction>
								<dynamic_friction>1</dynamic_friction>
								<viscous_friction>1</viscous_friction>
							</ElasticFoundationForce::ContactParameters>
						</objects>
						<groups />
					</ElasticFoundationForce::ContactParametersSet>
					<!--Slip velocity (creep) at which peak static friction occurs.-->
					<transition_velocity>0.1</transition_velocity>
				</ElasticFoundationForce>
				<ElasticFoundationForce name="Ggrasp_MCP4">
					<!--Flag indicating whether the force is disabled or not. Disabled means that the force is not active in subsequent dynamics realizations.-->
					<isDisabled>false</isDisabled>
					<!--Material properties.-->
					<ElasticFoundationForce::ContactParametersSet name="contact_parameters">
						<objects>
							<ElasticFoundationForce::ContactParameters>
								<!--Names of geometry objects affected by these parameters.-->
								<geometry>glass6 Iphal6</geometry>
								<stiffness>63000000</stiffness>
								<dissipation>0.2</dissipation>
								<static_friction>0.2</static_friction>
								<dynamic_friction>0.2</dynamic_friction>
								<viscous_friction>0.3</viscous_friction>
							</ElasticFoundationForce::ContactParameters>
						</objects>
						<groups />
					</ElasticFoundationForce::ContactParametersSet>
					<!--Slip velocity (creep) at which peak static friction occurs.-->
					<transition_velocity>0.1</transition_velocity>
				</ElasticFoundationForce>
				<ElasticFoundationForce name="Ggrasp_MCP4">
					<!--Flag indicating whether the force is disabled or not. Disabled means that the force is not active in subsequent dynamics realizations.-->
					<isDisabled>false</isDisabled>
					<!--Material properties.-->
					<ElasticFoundationForce::ContactParametersSet name="contact_parameters">
						<objects>
							<ElasticFoundationForce::ContactParameters>
								<!--Names of geometry objects affected by these parameters.-->
								<geometry>glass11 Iphal7</geometry>
								<stiffness>63000000</stiffness>
								<dissipation>0.2</dissipation>
								<static_friction>0.2</static_friction>
								<dynamic_friction>0.2</dynamic_friction>
								<viscous_friction>0.3</viscous_friction>
							</ElasticFoundationForce::ContactParameters>
						</objects>
						<groups />
					</ElasticFoundationForce::ContactParametersSet>
					<!--Slip velocity (creep) at which peak static friction occurs.-->
					<transition_velocity>0.1</transition_velocity>
				</ElasticFoundationForce>
				<ElasticFoundationForce name="Ggrasp_MCP4">
					<!--Flag indicating whether the force is disabled or not. Disabled means that the force is not active in subsequent dynamics realizations.-->
					<isDisabled>false</isDisabled>
					<!--Material properties.-->
					<ElasticFoundationForce::ContactParametersSet name="contact_parameters">
						<objects>
							<ElasticFoundationForce::ContactParameters>
								<!--Names of geometry objects affected by these parameters.-->
								<geometry>glass9 Iphal9</geometry>
								<stiffness>63000000</stiffness>
								<dissipation>0.2</dissipation>
								<static_friction>0.2</static_friction>
								<dynamic_friction>0.2</dynamic_friction>
								<viscous_friction>0.3</viscous_friction>
							</ElasticFoundationForce::ContactParameters>
						</objects>
						<groups />
					</ElasticFoundationForce::ContactParametersSet>
					<!--Slip velocity (creep) at which peak static friction occurs.-->
					<transition_velocity>0.1</transition_velocity>
				</ElasticFoundationForce>
				<ElasticFoundationForce name="Ggrasp_MCP4">
					<!--Flag indicating whether the force is disabled or not. Disabled means that the force is not active in subsequent dynamics realizations.-->
					<isDisabled>false</isDisabled>
					<!--Material properties.-->
					<ElasticFoundationForce::ContactParametersSet name="contact_parameters">
						<objects>
							<ElasticFoundationForce::ContactParameters>
								<!--Names of geometry objects affected by these parameters.-->
								<geometry>glass10 Iphal10</geometry>
								<stiffness>63000000</stiffness>
								<dissipation>0.2</dissipation>
								<static_friction>0.2</static_friction>
								<dynamic_friction>0.2</dynamic_friction>
								<viscous_friction>0.3</viscous_friction>
							</ElasticFoundationForce::ContactParameters>
						</objects>
						<groups />
					</ElasticFoundationForce::ContactParametersSet>
					<!--Slip velocity (creep) at which peak static friction occurs.-->
					<transition_velocity>0.1</transition_velocity>
				</ElasticFoundationForce>
				<ElasticFoundationForce name="Ggrasp_MCP4">
					<!--Flag indicating whether the force is disabled or not. Disabled means that the force is not active in subsequent dynamics realizations.-->
					<isDisabled>false</isDisabled>
					<!--Material properties.-->
					<ElasticFoundationForce::ContactParametersSet name="contact_parameters">
						<objects>
							<ElasticFoundationForce::ContactParameters>
								<!--Names of geometry objects affected by these parameters.-->
								<geometry>glass12 Iphal13</geometry>
								<stiffness>63000000</stiffness>
								<dissipation>0.2</dissipation>
								<static_friction>0.2</static_friction>
								<dynamic_friction>0.2</dynamic_friction>
								<viscous_friction>0.3</viscous_friction>
							</ElasticFoundationForce::ContactParameters>
						</objects>
						<groups />
					</ElasticFoundationForce::ContactParametersSet>
					<!--Slip velocity (creep) at which peak static friction occurs.-->
					<transition_velocity>0.1</transition_velocity>
				</ElasticFoundationForce>
				<ElasticFoundationForce name="Ggrasp_MCP4">
					<!--Flag indicating whether the force is disabled or not. Disabled means that the force is not active in subsequent dynamics realizations.-->
					<isDisabled>false</isDisabled>
					<!--Material properties.-->
					<ElasticFoundationForce::ContactParametersSet name="contact_parameters">
						<objects>
							<ElasticFoundationForce::ContactParameters>
								<!--Names of geometry objects affected by these parameters.-->
								<geometry>glass4 Iphal14</geometry>
								<stiffness>63000000</stiffness>
								<dissipation>0.2</dissipation>
								<static_friction>0.2</static_friction>
								<dynamic_friction>0.2</dynamic_friction>
								<viscous_friction>0.3</viscous_friction>
							</ElasticFoundationForce::ContactParameters>
						</objects>
						<groups />
					</ElasticFoundationForce::ContactParametersSet>
					<!--Slip velocity (creep) at which peak static friction occurs.-->
					<transition_velocity>0.1</transition_velocity>
				</ElasticFoundationForce>
				<ElasticFoundationForce name="Ggrasp_MCP4">
					<!--Flag indicating whether the force is disabled or not. Disabled means that the force is not active in subsequent dynamics realizations.-->
					<isDisabled>false</isDisabled>
					<!--Material properties.-->
					<ElasticFoundationForce::ContactParametersSet name="contact_parameters">
						<objects>
							<ElasticFoundationForce::ContactParameters>
								<!--Names of geometry objects affected by these parameters.-->
								<geometry>glass8 Iphal15</geometry>
								<stiffness>63000000</stiffness>
								<dissipation>0.2</dissipation>
								<static_friction>0.2</static_friction>
								<dynamic_friction>0.2</dynamic_friction>
								<viscous_friction>0.3</viscous_friction>
							</ElasticFoundationForce::ContactParameters>
						</objects>
						<groups />
					</ElasticFoundationForce::ContactParametersSet>
					<!--Slip velocity (creep) at which peak static friction occurs.-->
					<transition_velocity>0.1</transition_velocity>
				</ElasticFoundationForce>
				<ElasticFoundationForce name="Ggrasp_MCP5">
					<!--Flag indicating whether the force is disabled or not. Disabled means that the force is not active in subsequent dynamics realizations.-->
					<isDisabled>false</isDisabled>
					<!--Material properties.-->
					<ElasticFoundationForce::ContactParametersSet name="contact_parameters">
						<objects>
							<ElasticFoundationForce::ContactParameters>
								<!--Names of geometry objects affected by these parameters.-->
								<geometry>glass13 Thumb</geometry>
								<stiffness>63000000</stiffness>
								<dissipation>0.2</dissipation>
								<static_friction>0.2</static_friction>
								<dynamic_friction>0.2</dynamic_friction>
								<viscous_friction>0.3</viscous_friction>
							</ElasticFoundationForce::ContactParameters>
						</objects>
						<groups />
					</ElasticFoundationForce::ContactParametersSet>
					<!--Slip velocity (creep) at which peak static friction occurs.-->
					<transition_velocity>0.1</transition_velocity>
				</ElasticFoundationForce>
			

The below code is for the contact sphere created

Code: Select all

<ContactGeometrySet>
			<objects>
				<ContactSphere name="glass1">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>-0.022 0.075 0.002</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="glass2">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>-0.008 0.078 0.02</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.007</radius>
				</ContactSphere>
				<ContactSphere name="glass3">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.014 0.084 0.024</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="glass4">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>-0.016 0.01 0.01</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="glass5">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>-0.01 0.055 0.024</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="glass6">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>-0.025 0.054 -0.004</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.007</radius>
				</ContactSphere>
				<ContactSphere name="glass7">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>-0.0456 0.072 -0.015</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.007</radius>
				</ContactSphere>
				<ContactSphere name="glass8">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>-0.017 0.007 -0.01</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="glass9">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.025 0.043 0.018</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.008</radius>
				</ContactSphere>
				<ContactSphere name="glass10">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.003 0.036 0.02</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="glass11">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>-0.03 0.037 -0.0074</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="glass12">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>-0.007 0.013 0.02</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="glass13">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>-0.001 0.0835 0.025</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="Iphal7">
					<!--Body name to connect the contact geometry to-->
					<body_name>Iphalanx7</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.001 -0.0228 0.005</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="Iphal6">
					<!--Body name to connect the contact geometry to-->
					<body_name>Iphalanx6</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.003 -0.015 -0.00035</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="Iphal5">
					<!--Body name to connect the contact geometry to-->
					<body_name>Iphalanx5</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.001 -0.0126 0.0268</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="Iphal3">
					<!--Body name to connect the contact geometry to-->
					<body_name>Iphalanx3</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.005 -0.0126 0.004</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="Iphal2">
					<!--Body name to connect the contact geometry to-->
					<body_name>Iphalanx2</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.001 -0.017 0.005</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="Iphal1">
					<!--Body name to connect the contact geometry to-->
					<body_name>Iphalanx1</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.001 -0.03 0.004</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="Iphal9">
					<!--Body name to connect the contact geometry to-->
					<body_name>Iphalanx9</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.007 -0.01 0.0045</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.008</radius>
				</ContactSphere>
				<ContactSphere name="Iphal10">
					<!--Body name to connect the contact geometry to-->
					<body_name>Iphalanx10</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.003 -0.02 -0.0045</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="Iphal11">
					<!--Body name to connect the contact geometry to-->
					<body_name>Iphalanx11</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.001 -0.034 -0.022</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="Iphal15">
					<!--Body name to connect the contact geometry to-->
					<body_name>Iphalanx15</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.001 -0.023 -0.05</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="Iphal14">
					<!--Body name to connect the contact geometry to-->
					<body_name>Iphalanx14</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.009 -0.013 -0.0345</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.007</radius>
				</ContactSphere>
				<ContactSphere name="Iphal13">
					<!--Body name to connect the contact geometry to-->
					<body_name>Iphalanx13</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.005 -0.01 -0.0261</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="Thumb">
					<!--Body name to connect the contact geometry to-->
					<body_name>thumb</body_name>
					<!--Location of geometry center in the body frame-->
					<location>0.008 -0.065 0.051</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.007</radius>
				</ContactSphere>
			</objects>
		</ContactGeometrySet>

The joint moment values of MCPs remain the same even if i change the stiffness value .Normally shouldn't the moment values change if the stiffness value changes.Also even if i move any of the contact spheres from its position for seeing variations in the output,the moment values remain the same.What would be the the reason?

[Krishnakumar Sankar]

As I have created contact meshes for the finger segments, I have wrote the below code

Code: Select all

<ContactGeometrySet>
         <objects>
            <ContactMesh name="f2">
               <!--Body name to connect the contact geometry to-->
               <body_name>Iphalanx1</body_name>
               <!--Location of geometry center in the body frame-->
               <location>0.001 -0.03 0.004</location>
               <!--Orientation of geometry in the body frame-->
               <orientation> 0 0 0</orientation>
               <!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
               <display_preference>4</display_preference>
               <!--Display Color-->
               <color>0 1 1</color>
               <filename>fingers2.stl</filename>
            </ContactMesh>
            <ContactMesh name="f3">
               <!--Body name to connect the contact geometry to-->
               <body_name>Iphalanx3</body_name>
               <!--Location of geometry center in the body frame-->
               <location> 0.00075 -0.015 0.0005</location>
               <!--Orientation of geometry in the body frame-->
               <orientation>0 0 0</orientation>
               <!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
               <display_preference>4</display_preference>
               <!--Display Color-->
               <color>0 1 1</color>
               <filename>fingers3.stl</filename>
            </ContactMesh>
            
			<ContactSphere name="glass2">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>-0.022 0.075 0.002</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.0075</radius>
				</ContactSphere>
				<ContactSphere name="glass3">
					<!--Body name to connect the contact geometry to-->
					<body_name>glass</body_name>
					<!--Location of geometry center in the body frame-->
					<location>-0.008 0.078 0.02</location>
					<!--Orientation of geometry in the body frame-->
					<orientation>0 0 0</orientation>
					<!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
					<display_preference>4</display_preference>
					<radius>0.007</radius>
				</ContactSphere>
			</objects>
		</ContactGeometrySet>

My previous code on contact geometry part was , I created contact spheres for both finger segments and the glass.I think I have to create contact mesh for finger segments and contact spheres for glass surface . Is that right ?