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

S — Sensor port

frame

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

M — Custom measurement frame port

frame

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

m — Mass

scalar

Total mass for the collection of body elements.

Dependencies

To enable this port, select the Mass check box.

com — Center of Mass

vector

The center of mass for the collection of body elements.

Dependencies

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

I — Inertia Matrix

matrix

The inertia matrix for the collection of body elements.

Dependencies

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

Ic — Centered Inertia Matrix

matrix

The centered inertia matrix for the collection of body elements.

Dependencies

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

Ip — Principal Inertia Matrix

matrix

The principal inertia matrix for the collection of body elements.

Dependencies

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

R — Rotation Matrix

matrix

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

Sensor Extent — Determine the extent that the Inertia Sensor block measures

Body Group (default) | Mechanism

Extent that the Inertia 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.

Sensor Extent: Span Weld Joints — Include bodies connected by weld joints in a body group

cleared (default) | checked

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.

Sensor Extent: Exclude Grounded Bodies — Do not measure inertial properties of grounded bodies

cleared (default) | checked

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.

Measurement Frame — Determine the frame that the Inertia Sensor block uses for measurements

Attached (default) | World | Custom

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.

Mass — Total mass of measured bodies

cleared (default) | checked

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

Center of Mass — Center of mass coordinates

cleared (default) | checked

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.

Inertia Matrix — Measurement of the inertia tensor

cleared (default) | checked

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.

Centered Inertia Matrix — Measurement of the inertia tensor relative to the centered frame

cleared (default) | checked

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.

Principal Inertia Matrix — Measurement of the inertia tensor with respect to the principal inertia frame

cleared (default) | checked

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.

Rotation Matrix — Orientation of the principal inertia frame

cleared (default) | checked

Select the Rotation Matrix check box to measure 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.

Graphic: Type — Sensor visualization setting

Principal Inertia Frame (default) | Equivalent Inertia Ellipsoid | None

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.

Graphic: Size — Display size for the principal inertia frame

20 pixels (default) | positive scalar

Choose the display size for the principal inertia frame.

Dependencies

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

Visual Properties — Parameterizations for color and opacity

Simple (default) | Advanced

Parameterizations for specifying visual properties. Select Simple to specify diffuse color and opacity. Select Advanced to specify more visual properties, such as Specular Color, Ambient Color, Emissive Color, and Shininess.

Dependencies

To enable this parameter, set Type to From Geometry or Marker.

Color — True color as [R,G,B] vector on 0–1 scale

[0.5 0.5 0.5] (default) | three-element vector with values constrained to 0–1

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.

Dependencies

To enable this parameter, set :

1. Type to Marker.

2. Visual Properties to Simple.

Opacity — Graphic opacity

1.0 (default) | scalar in the range of 0 to 1

Graphic opacity, specified as a scalar in the range of 0 to 1. A scalar of 0 corresponds to completely transparent, and a scalar of 1 corresponds to completely opaque.

Dependencies

To enable this parameter, set:

1. Type to Marker

2. Visual Properties to Simple

Diffuse Color — True color as [R,G,B,A] vector on 0–1 scale

[0.5 0.5 0.5] (default) | three- or four-element vector with values constrained to 0–1

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.

Dependencies

To enable this parameter, set :

1. Type to Marker.

2. Visual Properties to Advanced.

Specular Color — Highlight color

[0.5 0.5 0.5 1.0] (default) | three-element vector | four-element vector

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.

Dependencies

To enable this parameter, set:

1. Type to From Geometry or Marker

2. Visual Properties to Advanced

Ambient Color — Shadow color

[0.15 0.15 0.15 1.0] (default) | three-element vector | four-element vector

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.

Dependencies

To enable this parameter, set:

1. Type to From Geometry or Marker

2. Visual Properties to Advanced

Emissive Color — Self-illumination color

[0.0 0.0 0.0 1.0] (default) | three-element vector | four-element vector

Graphic 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 (A) specifies the color opacity. Omitting the opacity element is equivalent to specifying a value of 1.

Dependencies

To enable this parameter, set:

1. Type to From Geometry or Marker

2. Visual Properties to Advanced

Shininess — Highlight sharpness

75 (default) | scalar with value constrained to 0–128

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.

Dependencies

To enable this parameter, set:

1. Type to From Geometry or Marker

2. Visual Properties to Advanced

Extended Capabilities

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

Version History

Introduced in R2019b