Variable Brick Solid

Solid brick with variable mass and size

• Library:

• Simscape / Multibody / Body Elements / Variable Mass

• 

Description

The Variable Brick Solid block adds to the attached frame a solid brick with variable mass and size. The mass and side lengths (x, y, and z) of the brick can each be a constant or vary with time. A variable quantity can be specified directly as a physical signal or it can be calculated as a function of the remaining quantities. Only one quantity, either mass or one side length, can be calculated during simulation.

A reference frame encodes the position and orientation of the solid in a model. The frame origin is located at the midpoint of the x- and y-dimensions and at the lower end of the z-dimension. These relationships are preserved during simulation. The z-dimension increases asymmetrically relative to the lower z-plane, along the positive direction of the z-axis.

Variable Brick with z-Dimension Calculated from Mass

Visualization is dynamic. Solid dimensions update continuously as they occur, in the visualization pane of Mechanics Explorer. The initial dimensions of the solid depend on the parameters and physical signals that you specify. It is possible for a variable dimension to begin with a zero value—for example, if it derives from a physical signal whose initial value is zero also.

Density can itself be constant or variable. This quantity is specified as a constant if at least one solid parameter is calculated during simulation. It is calculated as a variable if all solid parameters are explicitly specified, either as (constant) block parameters or as physical signals. As in the case of the solid blocks, you can specify a negative density, for example, to model voids in compound bodies.

Ports

Frame

R — Reference frame

frame

Local reference frame of the solid. This frame is fixed with respect to the solid geometry. Its origin is on the xy plane, in the geometrical center of the xy cross section. Connect this port to a frame entity—port, line, or junction—to resolve the frame placement in a model. For more information, see Working with Frames.

Physical Signal Input

lx — x-dimension of the brick

physical signal

Input port for the x-dimension of the brick.

ly — y-dimension of the brick

physical signal

Input port for the y-dimension of the brick.

lz — z-dimension of the brick

physical signal

Input port for the z-dimension of the brick.

m — Brick mass

physical signal

Input port for the mass of the brick.

Physical Signal Output

lx — x-dimension of the brick

physical signal

Output port for the x-dimension of the brick.

ly — y-dimension of the brick

physical signal

Output port for the y-dimension of the brick.

lz — z-dimension of the brick

physical signal

Output port for the z-dimension of the brick.

m — Brick mass

physical signal

Output port for the mass of the brick.

com — Center-of-mass coordinates of the brick

physical signal

Output port for the center of mass of the brick, reported as a three-element vector with Cartesian coordinates resolved in the reference frame of the solid.

I — Inertia matrix of the brick

physical signal

Output port for the inertia matrix of the brick, reported as a nine-element matrix and resolved in the reference frame of the block. The diagonal matrix elements are the moments of inertia. The off-diagonal elements are the products of inertia.

Parameters

Geometry and Inertia

X Length — Parameterization of the x dimension

Constant (default) | Calculate from Mass | Provided by Input

Parameterization of the x dimension of the solid—the length along the x-axis of the local reference frame. Select Constant to specify a fixed value as a block parameter. Select Provided by Input to specify a variable value as a physical signal input. Use the default setting (Calculated from Mass) to obtain this parameter from the specified solid density and remaining dimensions. Selecting Provided by Input exposes a new physical signal input port, labeled lx, through which to specify the variable value.

X Length: Value — Value of the x dimension

1 m (default) | scalar with units of length

Length of the solid along the x-axis of the local reference frame. The x dimension is constant when this block parameter is active.

Parameter Dependencies

This parameter is active when the X Length parameter is set to Constant.

Y Length — Parameterization of the y dimension

Constant (default) | Calculate from Mass | Provided by Input

Parameterization of the y dimension of the solid—the length along the y-axis of the local reference frame. Select Constant to specify a fixed value as a block parameter. Select Provided by Input to specify a variable value as a physical signal input. Use the default setting (Calculated from Mass) to obtain this parameter from the specified solid density and remaining dimensions. Selecting Provided by Input exposes a new physical signal input port, labeled ly, through which to specify the variable value.

Y Length: Value — Value of the y dimension

1 m (default) | scalar with units of length

Length of the solid along the y-axis of the local reference frame. The y dimension is constant when this block parameter is active.

Parameter Dependencies

This parameter is active when the Y Length parameter is set to Constant.

Z Length — Parameterization of the z dimension

Calculate from Mass (default) | Constant | Provided by Input

Parameterization of the z dimension of the solid—the length along the z-axis of the local reference frame. Select Constant to specify a fixed value as a block parameter. Select Provided by Input to specify a variable value as a physical signal input. Use the default setting (Calculated from Mass) to obtain this parameter from the specified solid density and remaining dimensions. Selecting Provided by Input exposes a new physical signal input port, labeled lz, through which to specify the variable value.

Z Length: Value — Value of the z dimension

1 m (default) | scalar with units of length

Length of the solid along the z-axis of the local reference frame. The z dimension is constant when this block parameter is active.

Parameter Dependencies

This parameter is active when the Z Length parameter is set to Constant.

Mass — Mass parameterization

Provided by Input (default) | Calculate from Geometry

Parameterization of the mass of the solid. Select Calculate from Geometry to obtain this parameter from the specified solid density and dimensions. Use the default setting (Provided by Input) to specify this parameter directly as a time-variable physical signal. This option exposes a new physical signal input port, labeled M, through which to specify the time-variable solid mass.

Mass: Density — Mass per unit volume of material

1000 kg/m^3 (default) | scalar in units of mass per unit volume

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. The default value, 1000 kg/m^3, is characteristic of polymers such as ABS plastic.

Parameter Dependencies

This parameter is active when the Mass parameter is set to Calculate from Geometry.

Sensing

X Length — Sensing selection for the x dimension

cleared (default) | checked

Sensing selection for the x dimension of the solid. Check to expose a new physical signal output port, labeled lx, through which to output the time-varying value of the x dimension.

Y Length — Sensing selection for the y dimension

cleared (default) | checked

Sensing selection for the y dimension of the solid. Check to expose a new physical signal output port, labeled ly, through which to output the time-varying value of the y dimension.

Z Length — Sensing selection for the z dimension

cleared (default) | checked

Sensing selection for the z dimension of the solid. Check to expose a new physical signal output port, labeled lz, through which to output the time-varying value of the z dimension.

Mass — Sensing selection for the total mass

cleared (default) | checked

Sensing selection for the total mass of the solid. Check to expose a new physical signal output port, labeled m, through which to output the time-varying value of the solid mass.

Center of Mass — Sensing selection for the center-of-mass coordinates

cleared (default) | checked

Sensing selection for the coordinates of the center of mass of the solid. Check to expose a new physical signal output port, labeled com, through which to output the time-varying coordinates. The output is a three-element vector with Cartesian coordinates resolved in the reference frame of the solid.

Inertia Matrix — Sensing option for the inertia matrix

cleared (default) | checked

Sensing selection for the inertia matrix of the solid. Check to expose a new physical signal output port, labeled I, through which to output the time-varying inertia matrix. The output is a nine-element matrix with the moments of inertia in the diagonal positions and the products of inertia in the off-diagonal positions. The moments and products of inertia are resolve in the inertia frame of resolution—a frame with axes parallel to those of the reference frame but origin at the center of mass.

Graphic

Type — Solid visualization setting

From Geometry (default) | Marker | None

Visualization setting for this solid. Use the default setting, From Geometry, to show the solid geometry. Select Marker to show a graphic marker such as a sphere or frame. Select None to disable visualization for this solid.

Marker: Shape — Shape of the graphic marker

Sphere (default) | Cube | Frame

Geometrical shape of the graphic marker. Mechanics Explorer shows the marker using the selected shape.

Marker: Size — Pixel size of the graphic marker

10 (default) | scalar with units of pixels

Size of the marker in units of pixels. The size does not change with zoom level.

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
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