MATLAB SIMULINK 3D ANIMATION 5 Bedienungsanleitung PDF herunterladen (Seite 38)

dimension, it is still necessary to define full 3D positions for all controlled

objects for their virtual reality visualization.

In order to simplify modelling in such cases, Simulink 3D Animation contains

the VR Placeholder and VR Expander blocks.

The VR Placeholder block sends out a special value that is interpreted as

“unspecified” by the VR Sink block. When this placeholder value appears on a

VR Sink input, whether as a single value or as an element of a vector, the

appropriate value in the virtual world stays unchanged.

The VR Signal Expander block creates a vector of predefined length, using

some values from the input ports and filling the rest with placeholder signal

values.

In order to control position of a virtual object from one-dimensional dynamic

model, use the VR Signal Expander block with the controlled dimension as its

input, its output is 3-component vector that can be used in VR Sink. The

remaining vector elements are filled with placeholder signals.

Use of the VR Signal Expander block is possible also when defining rotations.

When the axis of rotation (as a part of initial rotation of an object Transform

node) is defined in the VRML file, it is possible to send to the VR Sink block a

VRML rotation value consisting of 3 placeholder signals and the computed

angle, forming a valid 4-element [axis angle] vector.

5.3.4. Linking the Virtual Scene to a SimMechanics Model

SimMechanics is very well suited for 3D visualizations using Simulink 3D

Animation. Apart from other features that SimMechanics offers for modelling

mechanical assemblies, there are the following features that simplify the

visualization of SimMechanics models in virtual reality:

 SimMechanics and VRML coordinate systems are identical (right-handed

Cartesian systems with the same orientation of x, y, z azes.)

 In SimMechanics it is easily possible to work with both global and local

object coordinates, so it is easy to adapt the model to the structure of

the virtual scene exported from the CAD tool.

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MATLAB SIMULINK 3D ANIMATION 5 Bedienungsanleitung Seite 38