Solid ellipsoidal element with geometry, inertia, and color
Simscape / Multibody / Body Elements
The Ellipsoidal Solid block is a three-dimensional extension of the ellipse with geometry center coincident with the reference frame origin and semi-principal axes coincident with the reference frame x, y, and z axes.
The Ellipsoidal 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 Ellipsoidal 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.
Ellipsoidal 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.
Ellipsoid: Radii— Ellipsoid radii along the x, y, and z semiprincipal axes
[1,1,1] m(default) | scalar with units of length
Ellipsoid radii along the x, y, and z axes of the solid reference frame. The ellipsoid becomes a sphere if all radii are equal.
Type— Inertia parameterization to use
Calculate from Geometry(default) |
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 density.
Based on— Parameter to base inertia calculation on
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 known.
Mass if the total solid mass if known.
Density— Mass per unit volume of material
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
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 the reference frame port for connection to other blocks
Clear the check box to hide the reference frame port in the Solid block. Hiding the reference frame port suppresses the frame visualization in Mechanics Explorer. You must expose the reference frame port if the block has no custom frames.
New Frame— Create a custom frame for connection to other blocks
Select the Create button to define a new frame using the frame-creation interface. Each new frame appears on a row above the New Frame parameter. To edit an existing frame, select the Edit button . To delete an existing frame, select the Delete button .
Frame Name— MATLAB® string used to identify the custom frame
Frame identifier specified as a MATLAB string. This string identifies the frame port in the block diagram and in the tree view pane of Mechanics Explorer. Keep the frame name short to ensure it fits in the block icon width.
Frame Origin— Position of the custom frame origin
Select the location of the frame origin. Options include:
At Reference Frame Origin — Make the new frame origin coincident with the reference frame origin. This is the default option.
At Center of Mass — Make the new frame origin coincident with the solid center of mass. The reference frame origin is located at the center of mass in symmetrical shapes such as spheres and bricks but not in certain extrusions or revolutions.
Based on Geometric Feature — Place the new frame origin at the center of the selected geometry feature. Valid geometry features include surfaces, lines, and points. You must select a geometry feature from the visualization pane and then select the Use Selected Feature button. The name of the selected geometry feature appears in the field below this option.
Frame Axes: Primary Axis— Axis used to constrain the possible directions of the remaining frame axes
Select the axis of the new frame that you want to set as the primary axis. The primary axis constrains the possible orientations of the remaining two axes. Specify the orientation of the primary axis by selecting from the following options:
Along Reference Frame Axis — Align the primary axis with the selected axis of the reference frame.
Along Principal Inertia Axis — Align the primary axis with the selected principal inertia axis. The principal inertia axes are those about which the products of inertia are zero.
Based on Geometric Feature — Align the primary axis with the vector associated with the selected geometric feature. Valid geometric features include surfaces and lines.
Frame Axes: Secondary Axis— Axis used to constrain the possible directions of the remaining frame axis
Select the axis of the new frame that you want to set as the secondary axis. The secondary axis is the projection of the selected direction onto the normal plane of the primary axis. Select the direction to project from the following options:
Along Reference Frame Axis — Project the selected reference frame axis onto the normal plane of the primary axis. Align the secondary axis with the projection.
Along Principal Inertia Axis — Project the selected principal inertia axis onto the normal plane of the primary axis. Align the secondary axis with the projection. The principal inertia axes are those about which the products of inertia are zero.
Based on Geometric Feature — Project the vector associated with the selected geometry feature onto the normal plane of the primary axis. Align the secondary axis with the projection. Valid geometry features include surfaces and lines. You must select a geometry feature from the visualization pane and then select the Use Selected Feature button.