Adding a platform on full body model

[George Mastorakis]

Hi

I'm trying to add a couple of platforms on the FullBodyModel. It seems that the platforms are visually missing although they appear on the Navigator. I attach the .osim file if you like to have a look. Apologies for the zip file but there is a size restriction on uploads.

Thanks

George

[Thomas Uchida]

You're missing the geometry_file element under VisibleObject. There's a platform in the dynamic walker example (https://simtk.org/frs/download.php?file_id=3862); here's the XML:

Code: Select all

...
<VisibleObject>
    <!--Set of geometry files and associated attributes, allow .vtp, .stl, .obj-->
    <GeometrySet>
        <objects>
            <DisplayGeometry>
                <!--Name of geometry file .vtp, .stl, .obj-->
                <geometry_file>box.vtp</geometry_file>
                <!--Color used to display the geometry when visible-->
                <color> 1 1 1</color>
                <!--Name of texture file .jpg, .bmp-->
                <texture_file />
                <!--in body transform specified as 3 rotations (rad) followed by 3 translations rX rY rZ tx ty tz-->
                <transform> -0 0 -0 0 0 0</transform>
                <!--Three scale factors for display purposes: scaleX scaleY scaleZ-->
                <scale_factors> 1 1 1</scale_factors>
                <!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded-->
                <display_preference>4</display_preference>
                <!--Display opacity between 0.0 and 1.0-->
                <opacity>1</opacity>
            </DisplayGeometry>
        </objects>
        <groups />
    </GeometrySet>
    <!--Three scale factors for display purposes: scaleX scaleY scaleZ-->
    <scale_factors> 10 0.05 1</scale_factors>
    <!--transform relative to owner specified as 3 rotations (rad) followed by 3 translations rX rY rZ tx ty tz-->
    <transform> -0 0 -0 4.5 0 0</transform>
    <!--Whether to show a coordinate frame-->
    <show_axes>false</show_axes>
    <!--Display Pref. 0:Hide 1:Wire 3:Flat 4:Shaded Can be overriden for individual geometries-->
    <display_preference>4</display_preference>
</VisibleObject>
...

Perhaps you were looking at the "Simulation-Based Design to Prevent Ankle Injuries" example (http://simtk-confluence.stanford.edu:80 ... e+Injuries)? No .vtp file is specified in that model because there is a ContactHalfSpace defined on the platform and the ContactHalfSpace is drawn.

[George Mastorakis]

Great thanks!
You are right about using the "Simulation-Based Design to Prevent Ankle Injuries" since I would like to have contact forces with the platform. Will I have contact forces etc for the model as well as with the platform if I use the proposed solution with VisibleObject?

Thanks in advance.

George

[Thomas Uchida]

Will I have contact forces etc for the model as well as with the platform if I use the proposed solution with VisibleObject?

No, adding geometry to the platform body will just draw the geometry in the visualizer. As was done in the "Simulation-Based Design to Prevent Ankle Injuries" example (http://simtk-confluence.stanford.edu:80 ... e+Injuries), you will need to add contact geometry to the feet and platform (e.g., ContactSpheres and ContactHalfSpace). I suggest looking at the Models\ToyDropLanding\ToyLandingModel.osim model and the ankle injury example. (The visualizer draws contact geometry, so it won't be necessary to add "DisplayGeometry" to the platform body if you have attached a ContactHalfSpace to it.)

[George Mastorakis]

Thanks Tom

It seems that I had to add a HuntCrossleyForce variable to make the contact forces visible - on the platform and the human model.

It seems that the issue if resolved, but I will provide an update.