Solid spherical element with geometry, inertia, and color
Simscape / Multibody / Body Elements
The Spherical Solid block is a spherical shape with geometry center coincident with the reference frame origin.
The Spherical Solid block adds to the attached frame a solid element with geometry, inertia, and color. The solid element can be a simple rigid body or part of a compound rigid body—a group of rigidly connected solids, often separated in space through rigid transformations. Combine Spherical Solid and other solid blocks with the Rigid Transform blocks to model a compound rigid body.
Geometry parameters include shape and size. You can choose from a list of preset shapes or import a custom shape from an external file in STL or STEP format. By default, for all but STL-derived shapes, the block automatically computes the mass properties of the solid from the specified geometry and either mass or mass density. You can change this setting in the Inertia > Type block parameter.
A reference frame encodes the position and orientation of the solid. In the default configuration, the block provides only the reference frame. A frame-creation interface provides the means to define additional frames based on solid geometry features. You access this interface by selecting the Create button in the Frames expandable area.
You can view the calculated values of the solid mass properties directly in the
block dialog box. Setting the Inertia > Type parameter to
Calculate from Geometry causes
the block to expose a new node, Derived Values. Click the
Update button provided under this node to calculate the
mass properties and display their values in the fields below the button.
Derived Values Display
The block dialog box contains a collapsible visualization pane. This pane provides instant visual feedback on the solid you are modeling. Use it to find and fix any issues with the shape and color of the solid. You can examine the solid from different perspectives by selecting a standard view or by rotating, panning, and zooming the solid.
Select the Update Visualization button to view the latest changes to the solid geometry in the visualization pane. Select Apply or OK to commit your changes to the solid. Closing the block dialog box without first selecting Apply or OK causes the block to discard those changes.
Solid Visualization Pane
Right-click the visualization pane to access the visualization context-sensitive menu. This menu provides additional options so that you can change the background color, split the visualization pane into multiple tiles, and modify the view convention from the default +Z up (XY Top) setting.
Radius — Radius of the sphere
1 m (default) | scalar with units of length
Distance between the center of the sphere and its surface.
Entire Geometry — Export the true geometry of the block
off (default) |
Select Entire Geometry to export the true geometry of the Spherical Solid block which can be used for other blocks, such as the Spatial Contact Force block.
To enable this option, select Entire Geometry under the Export.
Type — Inertia parameterization to use
Geometry (default) |
Point Mass |
Inertia parameterization to use. Select
Mass to model a concentrated mass with negligible
rotational inertia. Select
Custom to model a
distributed mass with the specified moments and products of inertia. The
Calculate from Geometry,
enables the block to automatically calculate the rotational inertia
properties from the solid geometry and specified mass or mass
Based on — Parameter to base inertia calculation on
Density (default) |
Parameter to use in inertia calculation. The block obtains the inertia
tensor from the solid geometry and the parameter selected. Use
Density if the material properties are
Mass if the total solid mass if
Density — Mass per unit volume of material
1000 kg/m^3 (default)
Mass per unit volume of material. The mass density can take on a positive or negative value. Specify a negative mass density to model the effects of a void or cavity in a solid body.
Calculate from Geometry: Derived Values — Display of calculated values of mass properties
Display of the calculated values of the solid mass properties—mass, center of mass, moments of inertia, and products of inertia. Click the Update button to calculate and display the mass properties of the solid. Click this button following any changes to the block parameters to ensure that the displayed values are still current.
The center of mass is resolved in the local reference frame of the solid. The moments and products of inertia are each resolved in the inertia frame of resolution—a frame whose axes are parallel to those of the reference frame but whose origin coincides with the solid center of mass.
The option to calculate and display the mass properties is active
when the Inertia > Type block parameter is set to
Type — Graphic to use in the visualization of the solid
From Geometry (default) |
Choice of graphic to use in the visualization of the solid. The
graphic is by default the geometry specified for the solid. Select
Marker to show instead a simple graphic
marker, such as a sphere or cube. Change this parameter to
None to eliminate this solid altogether
from the model visualization.
Marker: Shape — Shape of the marker to assign to the solid
Sphere (default) |
Shape of the marker by means of which to visualize the solid. The motion of the marker reflects the motion of the solid itself.
Marker: Size — Width of the marker in pixels
10 (default) | scalar with units of pixels
Width of the marker in pixels. This width does not scale with zoom level. Note that the apparent size of the marker depends partly on screen resolution, with higher resolutions packing more pixels per unit length, and therefore producing smaller icons.
Show Port R — Show reference frame port for connection to other blocks
on (default) | off
Select to expose the R port.
New Frame — Create custom frame for connection to other blocks
Click the Create button to open a pane for creating a new body-attached frame. In this pane, you can specify the name, origin, and orientation for the frame.
To name the custom frame, click the text field of the Frame Name parameter. The name identifies the corresponding port on the solid block and in the tree view pane of the Mechanics Explorer.
To select the Frame Origin of the custom frame, use one of the following methods:
At Reference Frame Origin: Make the new frame origin coincident with the origin of the reference frame of the solid.
At Center of Mass: Make the new frame origin coincident with the center of mass of the solid.
Based on Geometric Feature: Make the new frame origin coincident with the center of the selected feature. Valid features include surfaces, lines, and points. Select a feature from the visualization pane, then click Use Selected Feature to confirm the location of the origin. The name of the origin location appears in the field below this option.
To define the orientation of the custom frame, under the Frame Axes section, select the Primary Axis and Secondary Axis of the custom frame and then specify their directions.
Use the following methods to select a vector for specifying the directions of the primary and secondary axes. The primary axis is parallel to the selected vector and constrains the remaining two axes to its normal plane. The secondary axis is parallel to the projection of the selected vector onto the normal plane.
Along Reference Frame Axis: Selects an axis of the reference frame of the solid.
Along Principal Inertia Axis: Selects an axis of the principal inertia axis of the solid.
Based on Geometric Feature: Selects the vector associated with the chosen geometry feature of the solid. Valid features include surfaces and lines. The corresponding vector is indicated by a white arrow in the visualization pane. You can select a feature from the visualization pane and then click Use Selected Feature to confirm the selection. The name of the selected feature appears in the field below this option.
FrameN — Edit or delete existing custom frame
Frames that you have created.
N is a unique identifying number for each
Click the text field to edit the name of an existing custom frame.
Click the Edit button to edit other aspects of the custom frame, such as origin and axes.
Click the Delete button to delete the custom frame.
To enable this parameter, create a frame by clicking New Frame.