Inertia Sensor

Sensor to measure the inertial properties of body groups or mechanisms

  • Library:
  • Simscape / Multibody / Body Elements

Description

Use the Inertia Sensor block to measure the inertial properties for collections of body elements in your Simscape Multibody model. Parameters that the Inertia Sensor block can measure include:

  • Mass

  • Center of mass

  • Inertia matrix

  • Centered inertia matrix

  • Principal inertia matrix

  • Orientation of principal inertia frame

The Inertia Sensor block connects to a frame in your Simscape Multibody model and uses the frame to determine which body group or mechanism is measured.

A body group is the set of all body elements that are connected to each other directly or through rigid transforms. The body group may include solid blocks, inertia blocks, variable mass blocks, or flexible body blocks. By default, two body elements that are connected by a weld joint are not considered to be a part of the same body group, though you may choose to group these bodies with the Span Weld Joints property.

A mechanism is the set of all connected body elements within the model. With mechanisms, you can choose to exclude grounded bodies with the Exclude Grounded Bodies property. A grounded body is any rigid body that is rigidly connected to a World Frame.

Ports

Input

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Sensor port to attach to a frame in the model. Use this port to determine which body group or mechanism is measured.

When Custom is selected, a second port, M, appears on the Inertia Sensor block. The Inertia Sensor block measures inertial properties relative to the frame connected to the M port.

Dependencies

To enable this port, set the Measurement Frame parameter to Custom.

Output

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Total mass for the collection of body elements.

Dependencies

To enable this port, select the Mass check box.

The center of mass for the collection of body elements.

Dependencies

To enable this port, select the Center of Mass check box.

The inertia matrix for the collection of body elements.

Dependencies

To enable this port, select the Inertia Matrix check box.

The centered inertia matrix for the collection of body elements.

Dependencies

To enable this port, select the Centered Inertia Matrix check box.

The principal inertia matrix for the collection of body elements.

Dependencies

To enable this port, select the Principal Inertia Matrix check box.

The rotation matrix for orientation of principal inertia frame relative to measurement frame.

Dependencies

To enable this port, select the Rotation Matrix check box.

Parameters

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Extent that the Intertia Sensor block measures, defined as Body Group or Mechanism.

Body Group

When Body Group is selected, the Inertia Sensor block measures inertial properties for the collection of body elements that are connected to each other directly or through rigid transforms. This includes solid, inertia, variable mass, or flexible bodies.

Mechanism

When Mechanism is selected, the Inertia Sensor block measures inertial properties for all connected body elements within the model.

If selected, this option causes body groups to include body elements that are connected via a weld joint.

Dependencies

To enable this option, set Sensor Extent to Body Group.

If selected, this option causes the Inertia Sensor block to measure inertial properties for the collection of body elements connected to the same mechanism as the Inertia Sensor block excluding any grounded bodies.

Dependencies

To enable this option, set Sensor Extent to Mechanism.

Attached

When Attached is selected, the Inertia Sensor block measures inertial properties relative to the same frame that is connected to the S port.

World

When World is selected, the Inertia Sensor block measures inertial properties relative to the World Frame.

Custom

When Custom is selected, the M port is exposed. The Inertia Sensor block measures inertial properties relative to the frame connected to the M port.

Select the Mass check box to measure the mass of the collection of body elements.

Select the Center of Mass check box to measure the center of mass of the collection of body elements, output as a 3-by-1 vector relative to the measurement frame. If the mass of the measured body group or mechanism is zero, the center of mass is undefined and a runtime error occurs.

Select the Inertia Matrix check box to measure the inertia tensor of the collection of body elements, output as a 3-by-3 matrix relative to the measurement frame.

Select the Centered Inertia Matrix check box to measure the inertia tensor of the collection of body elements, output as a 3-by-3 matrix relative to the centered frame. The centered frame is a frame whose origin coincides with the center of mass and whose axes are aligned with those of the measurement frame. If the mass of the measured body group or mechanism is zero, the centered inertia matrix is undefined and a runtime error occurs.

Select the Principal Inertia Matrix check box to measure the inertia tensor of the collection of body elements, output as a 3-by-3 matrix with respect to the principal inertia frame. The principal inertia frame is a frame with an origin that coincides with the center of mass and axes that are aligned with the principal axes of inertia. If the mass of the measured body group or mechanism is zero, the principal inertia matrix is undefined and a runtime error occurs.

Select the Rotation Matrix check box to specify the orientation of the principal axes of inertia with respect to the measurement frame as a 3-by-3 matrix. If the mass of the measured body group or mechanism is zero, the rotation matrix is undefined and a runtime error occurs.

Display of the inertial properties for the sensed collection of body elements, specified as Principal Inertia Frame, Equivalent Inertia Ellipsoid, or None.

Principal Inertia Frame

When Principal Inertia Frame is selected, the inertial properties are shown as an axes triad in the solid object.

Equivalent Inertia Ellipsoid

When Equivalent Inertia Ellipsoid is selected, the inertial properties are shown as an ellipsoid that has the same mass, moments, and products of inertia as the group of bodies being sensed.

None

When None is selected, the inertial properties are not displayed.

Choose the display size for the principal inertia frame.

Dependencies

To enable this option, set Graphic Type to Principal Inertia Frame.

Parameterization for specifying visual properties. Select Simple to specify color and opacity. Select Advanced to add specular highlights, ambient shadows, and self-illumination effects.

RGB color vector with red (R), green (G), and blue (B) color amounts specified on a 0–1 scale. A color picker provides an alternative interactive means of specifying a color. If you change the Visual Properties setting to Advanced, the color specified in this parameter becomes the Diffuse Color vector.

Graphic opacity specified on a scale of 0–1. An opacity of 0 corresponds to a completely transparent graphic and an opacity of 1 to a completely opaque graphic.

True color under direct white light specified as an [R,G,B] or [R,G,B,A] vector on a 0–1 scale. An optional fourth element specifies the color opacity also on a scale of 0–1. Omitting the opacity element is equivalent to specifying a value of 1.

Color of specular highlights specified as an [R,G,B] or [R,G,B,A] vector on a 0–1 scale. The optional fourth element specifies the color opacity. Omitting the opacity element is equivalent to specifying a value of 1.

Color of shadow areas in diffuse ambient light, specified as an [R,G,B] or [R,G,B,A] vector on a 0–1 scale. The optional fourth element specifies the color opacity. Omitting the opacity element is equivalent to specifying a value of 1.

Surface color due to self illumination, specified as an [R,G,B] or [R,G,B,A] vector on a 0–1 scale. The optional fourth element specifies the color opacity. Omitting the opacity element is equivalent to specifying a value of 1.

Sharpness of specular light reflections, specified as a scalar number on a 0–128 scale. Increase the shininess value for smaller but sharper highlights. Decrease the value for larger but smoother highlights.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Introduced in R2019b