Mathworks SIMMECHANICS 3 Visualization and Import Guide

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SimMechanics™ 3

Visualization and Import Guide

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SimMechanics™ Visualization and Import Guide

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Revision History

October 2008 Online only New for Version 3.0 (Release 2008b) March 2009 Online only Revised for Version 3.1 (Release 2009a) September 2009 Online only Revised for Version 3.1.1 (Release 2009b) March 2010 Online only Revised for Version 3.2 (Release 2010a)

Introducing Visualization and Animation

About SimM echanics Visualization .................. 1-2

Starting SimMechanics Visualization Using SimMechanics Visualization

About Body Color and Geometry: Default, Standard,

and Custom

About Body Color: Default and Custom About Body Geometry: Default, Standard, and Custom Standard Body Geometry: Equivalent Ellipsoids Standard Body Geometry: Convex Hulls Custom B ody Geometry and External Graphics Files

Hierarchy of Body, Machine, and Model Visualization

Settings

Visualized Geometries and Colors from Body Block

Settings Body Block Settings Affecting Body Visualization Visualization Settings in the Machine and Model

Hierarchy

..................................... 1-5

........................................ 1-11

....................................... 1-11

...................................... 1-13

................. 1-2

................... 1-3

............... 1-5

........ 1-5

............... 1-9

....... 1-12

Contents

.. 1-5

.... 1-10

Getting Started with the Visualization Window

Introducing the SimMechanics Visualization

Window

About the Visualization Window Opening and Updating the Visualization Window Visualization Toolbar and Its Controls

Controlling Body and Body Component Display

About Body and Body Component Display

......................................... 2-2

..................... 2-2

....... 2-2

................ 2-4

...... 2-6

............. 2-6

iii

Interpreting the Body Display Symbols and Shapes ..... 2-6

Changing Body Display Symbols Changing Body Display Shapes

..................... 2-7

...................... 2-7

Adjusting the Camera View

Setting the Background Color Interpreting the Camera Pro j ection, Field of View, and

Viewpoint Automatically Sizing the Camera Field of View Automatically Setting a Camera Viewpoint Actively Controlling the Camera View point Camera Viewpoint and Mouse Controls

Communicating with the Model from the Visualization

Window

Highlighting Bodies, B ody Components, and Body

Blocks Updating the Model Diagram Saving Visualization Settings to the Model

Controlling and Timing Simulation from the

Visualization Window

Starting, Pausing, and Stopping the Simulation Timing the Simulation

Controlling Animation

About Animation How Animation Works Automatically Adapting the Camera View to the D isplayed

Motion Changing How the Animation Is Updated Speeding Up the Animation in Real Time

...................................... 2-9

......................................... 2-17

........................................ 2-17

.................................. 2-23

........................................ 2-24

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........ 2-21

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iv Contents

Recording Animation

About Recording How Recording Works Recording Animations Compressing Anim ation Recordings Controlling the Size of the Recorded Animation Playing Recordings of Animation

.............................. 2-28

.................................. 2-28

.............................. 2-28

.................. 2-30

..................... 2-31

......... 2-31

Visualization Menus and Their Controls ............. 2-33

About the SimMechanics Visualization Window Menus View Menu Simulation Menu Model Menu Help Menu

....................................... 2-34

.................................. 2-35

...................................... 2-38

....................................... 2-39

Customizing Visualization and Animation

About Custom SimMechanics Visualization .......... 3-2

Customizing Visualization Settings Creating an External Virtual Reality Client

................... 3-2

............ 3-3

.. 2-33

Customizing Visualized Body Colors

Choosing Custom Body Colors Switching Between Default and Custom Body Colors

Customizing Visualized Body Geometries

Choosing Custom Body Geometries Switching Between Standard Body Geometries About STL Body Graphics Files Obtaining STL Body Graphics Files for Custom Body

Geometries

Switching Between Standard and Custom Body

Geometries

Visualizing with a Virtual Reality Client

About Virtual Worlds for Machines and Models Creating Virtual Worlds for SimMechanics Models Interfacing SimMechanics Models with Virtual Worlds Reference

.................................... 3-9

.................................... 3-10

........................................ 3-27

....................... 3-4

...................... 3-8

................ 3-4

............ 3-7

................... 3-7

............. 3-13

.... 3-4

......... 3-7

......... 3-13

...... 3-13

... 3-18

Importing Mechanical Models

Introducing M echanical Import ..................... 4-2

About Mechanical Import and CAD Translation Requirements for CAD Export and Mechanical Import Essential CAD Translation Steps

Generating New Models from Physical Modeling

XML

About Generated SimMechanics Models Based on CAD Generating a New Model from a Physical Modeling XML

Controlling New Model Import with Nondefault Options

............................................ 4-6

File

........................................... 4-7

.................... 4-4

........ 4-2

... 4-3

.. 4-6

.. 4-8

Working with Generated Models

About CAD-Based Models Common Features of CAD-Based Models Nondefault Features in Generated Models Manually Modifying and Extending Generated Models

After Import

Updating Generated Models Using Physical Modeling

XML

About Model Update and Mechanical Import Updating a Machine in a Generated Model with

Adding a New Machine to a Generated Model Replacing Generated Model or Subsystem Contents with a

Controlling Model Update at the Block Level

About Associativity and Updating Working with Associativity in Common Updating

Controlling How Update-Import Changes Individual Blocks

Associativity in an Updating Sequence Example

............................................ 4-22

Revisions

New Machine

Situations

and Connections

................................... 4-17

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vi Contents

Troubleshooting Imported and Updated Models

Best Practices for Creating and Exporting Assemblies

...... 4-46

... 4-46

Inserting Reference Coordinate Systems into Assemblies

Before Export

Controlling Mechanical Import to Assist

Troubleshooting Troubleshooting Erro rs During Model Generation Troubleshooting Errors During Model Update Troubleshooting M ode l Simulation Errors Troubleshooting SimMechanics an d Simulink Problems

.................................. 4-46

................................ 4-47

....... 4-47

.......... 4-48

............. 4-48

Computer-Aided Design Translation

About the CAD Translation Case Studies ............ 5-2

Introducing the Case Studies Requirements for the CAD Translation Case Studies About Specialized CAD Terms

........................ 5-2

....................... 5-3

.. 4-49

.... 5-3

Translating a CAD Part into a Body

Locating the Single-Part Assembly Files Viewing the CAD Assembly Exporting the CAD Assembly Generating the SimMechanics Model

Translating CAD Constraints into Joints

Modeling CAD and SimMechanics Degrees of Freedom Locating the Constraint Assembly Files Generating the Two-Part Models : Common Steps About the Common Block Structure of the Two-Part

Models Modeling a Six-DoF Joint Modeling a Prismatic Joint Modeling a Revolute Joint Modeling an Inplane Joint Modeling a Spherical-Spherical Massless Connector

Updating and Retranslating a CAD Pendulum

AboutAssemblyRe-ExportandModelUpdate Locating the Assembly Files Translating the Assembly For the First Time

........................................ 5-11

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........................ 5-7

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... 5-9

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..... 5-19

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vii

Updating the Original Imported Model with Chang es to

Bodies Adding a New Body to Create a Triple Pendulum Updating an Existing Generated Model While Retaining

Manual Joint Replacements SelectivelyUpdatinganExistingGeneratedModel

........................................ 5-28

....... 5-34

....................... 5-39

...... 5-40

Translating a CAD Robot Arm

Locating the Robot Arm Assembly Files Viewing the Robot Arm Assembly Exporting the Robot Arm Assembly Generating and Completing the Robot Arm Model Simulating and Observing the Robot Arm Motion

Translating a CAD Stewart Platform

Introducing the Stewart Platform Introducing the Stewart Platform Assembly Viewing the Stewart Platform Assembly Exporting the Stewart Platform Assembly Generating the Stewart Platform Model Visualizing the Stewart Platform M otion

...................... 5-42

............... 5-42

.................... 5-43

................... 5-44

................ 5-49

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............... 5-51

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....... 5-44

....... 5-48

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Index

viii Contents

Introducing Visualization and Animation

You can visualize your model’s bo dies using the SimMechanics™ visualization window. This overview explains the essentials of starting visualization and choosing body colors and geometries.

• “About SimMechanics Visualization” on page 1-2

• “About Body Color and Geometry: Default, Standard, and Custom” on

page 1-5

• “Hierarchy of Body, Machine, and Model Visualization Settings” on page

1-11

1 Introducing Visualization and Animation

About SimMechanics Visualization

In this section...

“Starting SimMechanics Visualization” on page 1-2

“Using SimMechanics Visualization” on page 1-3

Starting SimMechanics Visualization

Starting SimMechanics visualization requires two choices, one for your entire model, the second for each machine in your m odel. T hese choices are part of configuring your model for simulation, as discussed in “Starting Visualization and Simulation” in the SimMechanics User’s Guide. Implement your visualization cho ices at any time by clicking Apply or OK.

Enabling Visualization for an Entire Model

You enter the visualization settings for an entire model in the Visualization area of the SimMechanics node of the Configuration Parameters dialog. To open visualization, you must select at least one of these check boxes.

1-2

Model-wide visualization is turned off by default.

To start visualization, you must select at least one of the first two check boxes:

• Display machines after updating diagram forstaticvisualization

• Show animation during simulation for dynamic animation

Select the Show only port coordinate systems check box if you want to visualize only those Body coordinate systems with visible ports on their

About SimMechanics™ Visualization

respective Body blocks in the m odel. The default is unselected, so that all Body co ordinate systems are visualized on their respective bodies.

Visualizing All Bodies in a Machine

You can choose whether or not to visualize a specific machine in your model through the Visualization tab of its Ma ch in e Environment block dialog. A single window displays all selected machines in a model.

By default, each machine is selected for visualization. If you turn off machine visualization, your choice only affects that machine, not the entire model.

Other Si mMechanics Visualization Controls

All other visualization controls are located on the SimMechanics visualization window itself. You can access them once the window is open, as discussed in Chapter 2, “Getting Started with the Visualization Window”.

You control custom visualization choices for individual bodies in their respective Body dialogs.

Using SimMechanics Visualization

The visualization chapters guide you in making appropriate SimMechanics visualization choices, includ in g why you might want to visualize y o u r model’s bodies and animate their motion.

1-3

1 Introducing Visualization and Animation

Display Versus Animation

SimMechanics visualization serves two distinct purposes, static and dynamic. In both cases, you can change your observer viewpoint and navigate through the scene, as well as change the visualized body properties.

Static Display

You can display a static state of your model at different stages of modeling. Use static display in the initial state, during construction. Either:

• Open the visualization before or while you build your model. You display

each body as you add it to your model, if you also update the block diagram.

Having the visualization window open during model building lets you keep track of your model’s bodies and how they are connected. Yo u can see unphysical or mistaken constructions before you finish the model.

• Open the visualization after you finish the model. All the bodies in the

model appear together.

1-4

Also use static display after a simulation ends, or after you pause or stop it. In these cases, the visualization window shows the model at later times or in the final state.

Dynamic Animation

You can also display an animation of body motion while the Si m M echanics model is running. Use this feature to watch the model’s dynamics in three dimensions and visualize motions and relationships more easily than is possible with Scope blocks alone.

About Body Color and Geometry: Default, Standard, and Custom

In this section...

“About Body Color: Default and Custom” on page 1-5

“About Body Geometry: Default, Standard, and Custom” on page 1-5

“Standard Bo dy Geometry: Equivalent Ellipsoids” on page 1-5

“Standard Body Geometry: Convex Hulls” on page 1-9

“Custom Body Geometry and External Graphics Files” on page 1-10

About Body Color: Default and Custom

The initial default color of all visualizedbodiesisred. Youcanmodifythis default or replace it by custom colors for individual bodies, one at a time. See Chapter 3, “Customizing Visualization and Animation”.

About Body Geometry: Default, Standard, and Custom

You can choose how the visualization window displays the bodies in size and shape ( ge ometry ). There are two available standard geometries:

• Equivalent ellipsoid for each body, based on its mass properties and center

of gravity (CG) position

• Convex hull for each body, based on its Body coordinate systems (CSs)

The convex hull geometry is the initial default body geometry for all visualized bodies.

Standard Body Geometry: Equivalent Ellipsoids

The inertia tensor I of a rigid body is real and symmetric, so it has three real eigenvalues (I are the principal axes of the body. In the coordinate system defined by those axes, the inertia tensor is diagonal. The trace of the inertia tensor, Tr(I)=

, I2, I3) and three orthogonal eigenvectors. These eigenvectors

1-5

1 Introducing Visualization and Animation

I1+ I2+ I3, i s the same in any coordinate system with its origin at the body’s

center of gravity (CG).

Every rigid body has a unique equivalent ellipsoid, a homogeneous solid ellipsoid of the same inertia ten sor. In Cartesian coordinates, the ell ip soid surface is given by

⎡

⎣

⎛ ⎜

⎝

()

⎞ ⎟

⎠

()

−

⎤

()

⎦

++=

()

xyz

where m isthebody’smass. Thethreeparameters(ax, ay, az)arethe generalized radii of the ellipsoid. For axis i = 1,2,3,

aTrIm

522I

Triangle Inequalities

The principal moments (I1, I2, I3) must satisfy the triangle inequalities:

II I

+≥

231

III

+≥

31 2

II I

+≥

12 3

Violation of the triangle inequality for Iileads to an unphysical imaginary generalized radius a

Caution Visualizing the equivalent ellipsoid of a body whose principal moments do not satisfy the triangle inequalities leads to a SimMechanics warning indicating that one or more triangle inequalities have been violated. The simulation continues, but the body in violation is not displayed.

1-6

Ellipsoids with Special Symmetry

In general, all three Ii, i = 1,2,3, are unequal. Such a body is an asymmetric top. If two of the three I symmetric top. Thethirdaxisistheaxisofsymmetry. IfallthreeI

are equal (double degeneracy), the bo dy is a

are equal

About Body Color and Geometry: Default, Standard, and Custom

(triple deg eneracy), the body is a spherical top and dynamically equivalent to a homogeneous sphere.

Reduced-Dimension Ellipsoids

In special cases, the equivalent ellipsoid reduces to a planar, linear, or p oint figure.

Let (i,j,k) label the three axes (1,2,3) = (x,y,z)inanyorder.

• For a true ellipsoid,withnonzerovolume,allthea

are nonzero. Th e

triangle inequalities are strict inequalities in this case:

II I

jki

III

ki j

II I

ijk

• For an ellipse, with zero volume but nonzero area, one ai=0andtheother

two a

, akare nonzero. One of the triangle inequalities beco m es an equality:

II I

jki

III

ki j

II I

ijk

• For a line, with zero volume and area but nonzero length, two ai, aj=0and

the third a

II I

jki

III

ki j

II I

ijk

is nonzero. Two of the triangle inequalities become equalities:

+= +=

Equivalently, Ii= Ijare nonzero and Ik=0.

• For a point,withnospatialsize,allthreea

inequalities become equalities:

vanish. All three triangle

1-7

1 Introducing Visualization and Animation

II I

jki

III

ki j

II I

ijk

Equivalently, all three Iivanish.

Example: Simple Pendulum Rod

Consider the simple pendulum rod in “Visualizing a Simple Machine” in the SimMechanics Getting Started Guide.Youcanopenthemodelbyentering

mech_spen at the command line.

The rod length L =1m,anditsradiusr = 1 cm. The inertia tensor is

⎛ ⎜ ⎜

⎜ ⎝

⎛

⎞ ⎟

⎟ ⎟

⎠

20 0

⎜ ⎜

0120

⎜ ⎜

00 12

⎝

⎞ ⎟ ⎟ ⎟

⎟ ⎠

1-8

Because the rod has an axis of symmetry, the x-axisinthiscase,twoofits three p rincipal moments are equal: I radii are equal: a

= az. The rod is a symmetric top and, since r is much smaller

= Izz, a nd two of its three generalized

than L, its equivalent ellipsoid is almost a line of zero volume and area.

53 2L

The ge ne raliz ed radii of the equivalent ellipsoid are a

52r

and a

= az=

()

= 1.12 cm. This is the rod so displayed:

()

= 0.646 m

About Body Color and Geometry: Default, Standard, and Custom

Standard Body Geometr y: Convex Hulls

Every Body has at least one Body coordinate system (CS) at the CG. A Body also has one or more extra Body CSs for the attached Joints, as well as possible Actuators and Sensors. Each Body CS has an origin point, and the collection of all these points, in general, defines a volume in space. The minimum outward-bending surface enclosing such a volume is the convex hull of the Body CSs, and this is the alternative standard body geometry. The SimMechanics convex hull excludes the CG CS.

To enclose a nonzero volume, this set must have at least four non-coplanar Body CSs. Three non-collinear Body CSs are displayed instead by a triangle, and two non-coincident origins by a line. One origin is displayed just as apoint.

Four or more coplanar origins are displayed as a triangle, three or more collinear origins are displayed as a line, and two or more coincident origins are displayed as a point.

Example: Four-Cylinder Engine Crank

Open the four-cylinder engine model by entering mech_fceng at the command line. Start visualization.

1-9

1 Introducing Visualization and Animation

Open the Engine Block subsystem and note the Crank block representing the engine crank. This Body block has five coplanar Body CSs, not including the CG CS. Visualize the engine as convex hul ls and click the Crank body, the largest body. The convex hull forms a planar polygon.

1-10

Custom

In plac geomet

s. See Chapter 3, “Customizing Visualization and Animation”.

bodie

Body Geometry and External Graphics Files

e of the standard body geometry choices, you can provide a custom

ry defined with external graphics files for one or more individual

Hierarchy of Bod y, Machine, and Model Visualization Settings

Hierarchy of Body, Machine, and Model Visualization Settings

In this section...

“Visualized Geometries and Colors from Body Block Settings” on page 1-11

“BodyBlockSettingsAffectingBodyVisualization”onpage1-12

“Visualization Settings in the Machine and Model Hierarchy” on page 1-13

Visualized Geometries and Colors from Body Block Settings

The SimMechanics visualization window visualizes bodies repre s en ted by Body blocks in your model. The visualization information that the window uses from the model comes strictly from the mass, coordinate system, and visualization properties set individually in each Body block’s dialog.

Note The window itself contains addi t ion a l visualization controls that affect visualized body geometries and colors. See Chapter 2, “Getting Started with the Visualization Window”.

1-11

1 Introducing Visualization and Animation

1-12

Body Block and V isu al ization Window Setti ngs Control Body Visualization

Body Block Settings Affecting Body Visualization

How settings in Body block dialogs affect visualization depends on which type of body geometry and which color you ch oose for a particular body. The Body dialog contains three classes of such choices.

Mass Properties

The principal inertial moments and the mass of a body determine the size and shape of its equivalent ellipsoid.

Body Coordinate Systems: Origins and Orientation

The relative positions of the Body’s coordinate systems (CSs) determine the size and shape of its convex hull.

Visualization

The color choice in the Body dialog’s Visualization tab determines the color of the visualized body.

Hierarchy of Bod y, Machine, and Model Visualization Settings

You make the choice of convex hull or equivalent ellipsoid to visualize an individual body in the Body dialog’s Visualization tab.

If you choose a custom body geometry for a Body, the external body geometry file referenced in the Body dialog’s Visualization tab determines the visualized body’s size and shape .

Note The choice of standard or custom body geometry has no effect on the visualized body’s color. The choice of body color has no effect on the visualized body’s geometry.

Visualization Settings in the Machine and Model Hierarchy

SimMechanics models start with initial default visualization settings. A model a nd machines within the model also possess, respectively, model-wide and machine-wide default visualization settings. Visualization settings are inherited from the highest level (model) through machines to individual Bodies. You can change these default and inherited settings.

Chapter 3, “Customizing Visualization and Animation” discusses the controls you need to adjust to change these default and inherited settings at the model, machine, and body levels.

1-13

1 Introducing Visualization and Animation

1-14

Inheritance Hierarchy of Default Visualization Settings

Initial Default Settings for a Model

The initial default visualization settings for an entire model are:

• Model-wide default body color: red (RGB value o f

• Model-wide default body geometry: convex hull

[1 0 0])

Machine Inheritance of Model-Wide Default Settings

The initial default visualization settings for a m achine are:

Hierarchy of Bod y, Machine, and Model Visualization Settings

• Machine-wide default body color: inherit model-wide default

• Machine-wide default body geometry: inherit model-wide d efault

Body Inheritance of Machine-Wide Default Settings

The initial default visualization settings for a Body are:

• Default Body color: inherit machine-wide default

• Default Body geometry: inherit machine-wide default

1-15

1 Introducing Visualization and Animation

1-16

Getting Started with the Visualization Window

The SimMechanics visualization window allows you to control how you view yourmodel’sbodiesinbothstaticdisplay and dynamic simulation-based animation. It also allows you to record animations.

• “Introducing the SimMechanics Visualization Window” on page 2-2

• “Controlling Body and Body Component Display” on page 2-6

• “Adjusting the Camera View” on page 2-9

• “Communicating with the Model from the Visualization Window” on page

2-17

• “Controlling and Timing Simulation from the Visualization Window” on

page 2-21

• “Controlling Animation” on page 2-23

• “Recording Animation” on page 2-28

• “Visualization Menus and Their Controls” on page 2-33

2 Getting Started with the Visualization Window

Introducing the SimMechanics Visualization Window

In this section...

“About the Visualization Window” on page 2-2

“Opening and Updating the Visualization Window” on page 2-2

“Visualization Toolbar and Its Controls” on page 2-4

About the Visualization Window

The visualization window is an integral part of SimMechanics software. With it, you can visualize y our machines using a comprehensive set of display controls, interact with your model, and watch and record animations.

The window uses a distinctive set of symbols and shapes to display bodies and Body coordinate systems (CSs). This section is an overview of what you can do with the SimMechanics window.

2-2

Caution The S imMechanics visualization window resembles a MATLAB Graphics figure window. But it is not a feature of MATLAB and has no figure handle.

Opening and Updating the Visualization Window

Starting visualization and choosing the default display options are discussed in “About SimMechanics Visualization” on page 1-2.

• Once you configure your SimMechanics model for visualization, select

Update Diagram from the model’s Edit menu (or press Ctrl+D).

The window opens and displays the machines in your model that you have chosen to visualize. O n e window displays all selected machines simultaneously.

• To synchronize the static visualization display with you r model, reselect

Update Diagram at any time.

This figure shows a model with the default background color.

Introducing the SimMechanic s ™ Visualization Window

SimMechanics™ Visualization Window Displaying a Four-Cylinder Engine (Isometric V iew)

Menu Bar Versus Toolbar Controls

Onceyouopenthevisualizationwindow,youhavetwowaystocontrolthe display and carry out these tasks:

• Use the buttons in the toolbar. Every feature on this toolbar occurs in the

menus, although the reverse is not true. See “Visualization Toolbar and Its Controls” on page 2-4.

2-3

2 Getting Started with the Visualization Window

• Use the menus in the menu bar. The menu contains specialized items and

submenus. See “Visualization Menus and Their Controls” on page 2-33.

Note Changing the display settings using the visualization window controls changes only your immediate view in the display window. By itself, it does not change the visualization settings in the model.

Ifyouwanttosaveachangeinthevisualization window settings to the model, and thus change the model’s visualization settings, see “Communicating with the Model from the Visualization Window” on page 2-17.

Visualization Toolbar and I ts Controls

You can activate or change most visualization features by selecting buttons on the window toolbar, instead of selecting items from the menus. The setting changes initiated by the toolbar are the same as the corresponding menu actions: either you activate a feature, enable or disable a feature, or initiate an immediate action.

2-4

Hovering your mouse cursor over a toolbar button displays the button’s tooltip indicating its function.

SimMechanics™ Toolbar Buttons

Introducing the SimMechanic s ™ Visualization Window

Toolbar Relationship to the Menus

You can access all of the toolbar functions in the menus as an alternative. The toolbar reproduces most of the menu functions.

See “Visualization Menus and Their Controls” on page 2-33 for a complete overview of the visualization window controls.

2-5

2 Getting Started with the Visualization Window

Controlling Body and Body Component Display

In this section...

“About Body and Body Component Display” on page 2-6

“Interpreting the Body Display Symbols and Shapes” on page 2-6

“Changing Body Display Symbols” on page 2-7

“Changing Body Display Shapes” on page 2-7

About Body and Body Component Display

You can change how bodies look in the SimMechanics visualization window. This section explains how to control body and body compo n ent display.

Interpreting the Body Display Symbols and Shapes

When a visualization window opens, it uses distin ctive conventions to display the bodies of your model.

2-6

Body Component Display

Body components are d isplayed with two distinctive symbols:

• The center of gravity (CG) point of each body is marked by a half-filled

circle-plus symbol

• Each Body coordinate system (CS) is marked by coordinate axis triads. The

color coding is X-Y-Z ax es = RGB = red-green-blue.

Controlling Body and Body Component Display

Body Surface Display

The window displays all the bodies of every machine with visualization enabled. Theentirebodysurfaceisshadedwiththecoloryouchooseforit.Its shape is one of these:

• Convex hull: a line, one or more joined surface patches, or a closed surface

enclosing a volume

• Equivalent ellipsoid

• A custom shape

Changing Body Display Symbols

You can turn off the CS triads, the CG symbols, or both using the toolbar, with the Display Centers of Gravity and Display Coordinate Systems buttons.

You can activate or deactivate each button separately. The default for both is active.

Four-Cylinder Engine: Cylinder Piston With and Without Body CS Triads and CGs (Detail)

Changing Body Display Shapes

You can switch among three possible display shape options using the toolbar. They are mutually exclusive; one is always active.

2-7

2 Getting Started with the Visualization Window

• Clicking the Set Body Geometries to Convex Hulls button displays

allbodiesasconvexhulls,regardless of the visualization settings in the Body blocks in the model.

• Clicking the Set Body Geometries to Ellipsoids button displays all

bodies as convex hulls, regardless of the visualization settings in the Body blocks in the model.

• Clicking the Set Body Geometries to Individual Body Settings button

displays each body according to the visualization settings in its Body block in the model. This is the default.

2-8

rt Platform: Bodies Displayed as Convex Hulls and as Equivalent Ellipsoids

Stewa

Adjusting the Camera V iew

In this section...

“Setting the Background Color” on page 2-9

“Interpreting the Camera Projection, Field of View, and Viewpoint” on page 2-9

“Automatically Sizing the Camera Field of View” on page 2-11

“Automatically Setting a Camera Viewpoint” on page 2-12

“Actively Controlling the Camera Viewpoint” on page 2-13

“Camera Viewpoint and Mouse Contro ls” on page 2-14

Setting the Background Color

You must use the menu bar to change the background color of the display window within th e SimMechanics visualization window.

Adjusting the Camera View

1 Open View,thenselectChange Background Color. A color palette

opens.

2 Select a color. Click OK to implement your choice. The background color

changes immediately.

The color palette for the background is the same as the palette for custom body color. See “Customizing Vis ua l ize d Body Colors” on page 3-4.

Interpreting the Camera Projection, Field o f View, and Viewpoint

To properly interpret what you see in visualization, imagine that the display window shows the field of view of a camera. The properties of this virtual camera determine most of what you need to know about controlling your view of the model’s machines.

2-9

2 Getting Started with the Visualization Window

2-10

Visuali

zation Window Camera Field and Visualized Scene

Visualization and Orthographic Projection

The vis threelines windo

ualization window uses orthographic (parallel) projection to reduce a

dimensional scene to two dimensio ns on your screen. That is, parallel

of view representing depth converge to a point only at infinity. The

w displays the scene without finite perspective.

Camera Field of View, Viewpoint, and Frame Size

ield of view is what you see within the virtual camera frame. The virtual

The f

ra’s viewpoint is the point and direction from which it views the scene.

came

virtual camera frame has a size or aperture.

The

Adjusting the Camera View

Zooming. Changing the camera frame size or aperture, then shrinking or expanding the overall size of the machines, is the equivalent of zooming in or out. The camera cannot zoom directly, because there is no point of convergence or perspective.

Panning. Panning changes the camera’s virtual location without changing its direction of view. It means moving the camera frame horizontally or vertically in a constant virtual plane, maintaining the orientation of the camera frame.

Rotating. Rotating means viewing the scene from a different direction, wh ile maintaining a constant zoom (effective distance from the machines).

A rotation rotates about the center of the geometric bounding box containing all the objects in the field of view. (This geometric center is unrelated to body pro perties , such as Body coordinate systems or centers of gravity.) The viewpoint is moved to another point on the virtual sphere with this same geometric center. The view direction changes to maintain the geometric center at the center of the display window.

World Coordinate System Axes Indicate Orientation Only

The World CS axis triad always appears at the lower-left corner of the display window.

The directions of the axes indicate orientation only. The position of the axes does not, in general, indicate the position of the World coordinate system (CS) origin.

Automatically Sizing the Camera Field of View

You can automatically resize the camera’sfieldoraperturesizetofitallthe visualized objects. This step is equivalent to an automatic zoom. It d oes not rotate the viewpoint or pan the camera.

2-11

2 Getting Started with the Visualization Window

To fit the field of view to size, click the Fit to View button on the toolbar. The camera field resizes itself immediately.

2-12

Automatically Setting a Camera Viewpoint

You can automatically change your viewpoint of the visualized bodies by clicking one of the six viewpoint buttons on the toolbar. The action applies immediately.

Clicking these buttons is equivalent to setting a plane of view defined by the World CS axes. Except for the isometric view, these predefine d viewpoints always have one a xis perpendicular to the plane of view (pointing into or out of the plane of view). The isometric view is a viewpoint direction with equal

ection cosines (all

dir

default is the front view, with X pointing right, Y pointing up, and Z

The

nting out of the plane of view.

poi

13/

Adjusting the Camera View

Toolbar Button

Front View

(default)

Back View

Top View

Bottom View

Left View

Right View

Isometric View

Axes and Orientation of View Plane

X points right – Y points up

X points left – Y points up

X points rig ht – Z points down

X points right – Z points up

Z points right – Y points up

Z points left – Y points up

X points down and right – Y points up – Z points

down and left

Actively Controlling the Camera Viewpoint

The four selection-viewpoint toolbar control buttons enable certain interactions between your mouse and the display w indow through point-and-click or point-click-hold-and-roll.

These four toolbar-menu controls are mutually exclusive; you can activate at most one of them at a time. The default is for the Select Tool to be activ e.

• Enable a tool by clicking on its button.

• Disable all of them by clicking the currently active tool button.

Function

Select bodies

Viewpoint controls

Tool

Select

(default)

Rotate

Pan

Zoom

How to Use

Point with the mouse at a visualized body, then click on any mouse button.

Point with the mouse anywhere in display window. Then left-click, holding the mouse button, and roll mouse.

2-13

2 Getting Started with the Visualization Window

Results of Rolling t he Mouse with the Viewpoint Controls

With one of the three viewpoint control tools enabled, rolling the mouse produces one of three possible results in the display window.

Rotate Tool. Rolling so that the arrow moves in the display window along a line, rotates the view about that line. R olling in a more complex figure rotates the view in a m ore complex way.

Pan Tool. Rolling forward, back, left, or right pans up, down, left, or right, respectively.

Zoom Tool. Rolling forward or back zooms out or in, respectively. You zoom toward or away from the point that you initially clicked on. Rolling left or right does nothing.

ForMoreAbouttheSelectTool

See “Highlighting Bodies, Body Components, and Body Blocks” on page 2-17.

2-14

Camera Viewpoint and Mouse Controls

The four selection-viewpoint tool controls and the computer mouse have a complementary relationship to each other.

Normal Versus Dynamic Mouse Control

In normal mouse control, the left mouse button’s function corresponds to the function activated in the menus or toolbar. Depending on which function you activate from the menu or toolbar, you can switch the left mouse button from normal to dynamic mouse control and back. “Actively Controlling the Camera Viewpoint” on page 2-13 explains this case.

In dynamic mouse control, the viewpoint controls are disabled from the menu or toolbar. (Either the Select Tool is enabled, or all four selection-viewpoint controls are disabled from the menu or toolbar.) You can still exercise the viewpoint controls with the three mouse buttons, which are mapped one-to-one to the viewpoint controls.

Adjusting the Camera View

Note If your mouse has fewer than three buttons, y ou cannot access the dynamic mouse control functions associated with the missing button or buttons.

Normal and Dynamic Mouse Control with Left Mouse Button

The left mouse button’s mapping is more complex.

Viewpoint Control

Normal: Pan

Normal: Zoom

Dynamic: Rotate

Active

If Pan Tool is enabled from menu or toolbar

If Zoom Tool is enabled from menu or toolbar

If Pan and Zoom Tools are disabled from menu or toolbar

Dyna

The center and right mouse buttons’ mappings are always dynamic.

How to Use

Pan field of view by clicking and holding anywhere in display window and rolling mouse.

Zoom field of view by clicking and holding anywhere in display window and rolling mouse.

If Select Tool is disabled from menu or toolbar:

If Select Tool is enabled from menu or toolbar:

Rotate viewpoint by clicking and holding anywhere in display window and rolling mouse.

Rotate on only rollin Click selec viewp

viewpoint by clicking and holding

background in display window and

gmouse.

ing on a visualized body in this case

ts the body and has no effect on

oint.

mic Mouse Control with Center and Right Mouse Buttons

2-15

2 Getting Started with the Visualization Window

Mouse Button

Center

Right Dynamic:

Viewpoint Control

Dynamic: Pan

Zoom

Active

If Select Tool is disabled from menu or toolbar:

If Select Tool is enabled from menu or toolbar:

If Select Tool is disabled from menu or toolbar:

If Select Tool is enabled from menu or toolbar:

How to Use

Pan field of view by clicking and holding anywhere in display window and rolling mouse.

Pan field of view by clicking and holding on only background in display window and rolling m ouse. Clicking on a visualized body in this case selects the body and has no effect on field of view.

Zoom field of view by clicking and ho lding anywhere in display window and rolling mouse.

Zoom field of view by clicking and holding on only background in display window and rolling m ouse. Clicking on a visualized body in this case selects the body and has no effect on field of view.

2-16

Communicating with the Model from the Visualization Window

In this section...

“Highlighting Bodies, Body Components, and Body Blocks” on page 2-17

“Updating the Model Diagram” on page 2-18

“Saving Visualization Settings to the Model” on page 2-19

Highlighting Bodies, Body Components, and Body Blocks

If you have the Select Tool enabled, clicking a body, Body coordinate system (CS),orBodycenterofgravity(CG)in the SimMechanics visualization window causes the following:

• The displayed body or body component changes color:

- A selected body surface or CS triad becomes yellow.

- A selected CG changes from white-black to yellow-black.

• The visualization window displays the associated Body block or Body CS

name and its path at the low er left just below the display window, in the status bar.

• The associated Body block is outlined in red in the model window.

To unhighlight, click the highlighted body again. You can select and highlight a body both in static displ ay and during simulation.

2-17

2 Getting Started with the Visualization Window

SimMechanics™ Visualization Window with Highlighted Body and Body Block (Four-Cylinder Engine)

Enabling and Disabling Highlighting

You can enable or disable the highlighting of model Body blocks from the Model menu item Enable Model Highlighting. The default is enabled.

Whether model highlighting is enabled or disabled, clicking a body or body component in the window always highlights it. If you disable model highlighting, the associated Body block is not highlighted when you click the displayed body or body component.

Updating the Model Diagram

You can update your Simulink model diagram from the model toolbar or Edit menu, or by pressing Ctrl+D from the keyboard.

You can also update it by clicking the Update Simulink Diagram button in the visualization window toolbar.

2-18

Communicating with the Model from the Visualization Window

Saving Visualiz

As you work with t setting changes

• Changes you mak

while the wind then upon reop whatever mode Machine, and

• If you want to

controls be the Save Vis window tool the model it

• If you want

you must sa model too

lbar.

he visualization settings, you might want to save the

that you make.

e to the visualization settings apply only to the display

ow is open. If you do nothing else and close the window,

ening the visualization window, the display will revert to l requires for visualization settings. See “Hierarchy of Body,

Model V isualization Settings” on page 1-11.

save the display setting changes you made from the window

fore closing the window, you must save them to the model. Click

ualization Settings to Model buttononthevisualization bar. A warning dialog ap pears, asking if you want to save self.

to save these display setting changes before closing the model, ve or resave the model itself. Click the Save button in the

ation Settings to the Model

2-19

2 Getting Started with the Visualization Window

2-20

Caution If the changes to the display settings include changing the displayed body geometries, the saved visualization settings will make the visualization window display whatever the setting requires (all conve x hulls, all equivalent ellipsoids, or individual body geometries). But the saved visualization display settings do not change the visualization settings at the model, machine, or Body block level in the model described in Chapter 1, “Introducing Visualization and Animation”.

Controlling and Timing Simulation from the Visualization Window

In this section...

“Starting, Pausing, a nd Stopping the Simulation” on page 2-21

“Timing the Simulation” on pag e 2-21

Starting, Pausing, and Stopping the Simulation

You can control a simulation from the SimMechanics visualization window with the pair of simulation control buttons. The pair takes two different appearances, depending on whether the simulation is running.

With Simulation Stopped

From left to right, the buttons are Start and Stop,withStop disabled:

With Simulation Running

From left to right, the buttons are Pause and Stop: .

• If you pause a running simulation, restarting it begins the simulation at

the simulated time when it was stopped.

• If you stop a running simulation, restarting it begins the simulation at a

simulated time of zero.

Timing the Simulation

Once you start the simulation, you can track the simulation time at the lower right of the visualization window, in the status bar, if the simulation time display is active.

2-21

2 Getting Started with the Visualization Window

2-22

Simulation Time Display (Robot Arm Simulation with Visualized Body CSs and CGs Deactivated)

Activating and Deactivating the Simulation Time Display

You can activate or deactivate the simulation time display using the Display Simulation Time button on the toolbar. The default is active.

Controlling Animation

In this section...

“About Animation” on page 2-23

“How Animation Works” on page 2-23

“Automatically Adapting the Camera View to the Displayed Motion” on page 2-24

“Changing How the Animation Is Updated” on page 2-25

“Speeding Up the Animation in Real Time” on page 2-27

About Animation

When you start a simulation with visualization and animation enabled, the SimMechanics visualization window displays the body motion. This section shows how you can control the animation.

Controlling Animation

How Animation Works

The v isualization window displays the animated bodies in whatever camera view you previously set before starting simulation. By default, the cam era remainsatrestinWorld.

The animation that you see in the display window is the result of three distinct processes operating in parallel.

• Simulink

• Simulink updates the model outputs at every output sample time step.

• During animation, the visualization window updates the display of the

bodies at every visualization sample time step.

Each updated, displayed simulation scene is also called a frame.

By default, the output sample times are every major time step, and the visualization sample times are the output sample tim es. But, within limits, you can change the relationships among these time steps.

updates the model simulation at every simulation time step.

2-23

2 Getting Started with the Visualization Window

Caution Because visualization needs the model outputs to update the

animation, the visualization sample time should be equal to or longer than the m odel output sample time. If the visualization sample time is shorter, the displayed animation is updated at the model output sample times.

Automatically Adapting the Camera View to the Displayed Motion

As the bodies move in the animation, the camera view you set for the static case before simulation might not encompass their full range of motion. Or the bodies might move out of the field of view altogether.

You can require the display window to adapt the field of view dynamically to the animation with the Enable Automatic Expanding Fit and Enable Automatic Tight Fit buttons on the toolbar. These buttons are mutually exclusive. The default for both is disabled.

2-24

Allowing the Field of View to Expand with the Moving Bodies

If the animated bodies tend to move out of the field of view once, repeatedly, or continually, click the Enable Automatic Expanding Fit button. The field of view will then expand as necessary to encompass the geometric bounding box of all the bodies, as visualized. The camera remains at rest in World.

Keeping the Field of View Limited to the Moving Bodies

If you want your field of view to encompass just the moving bodies and track them as they move, click the Enable Automatic Tight Fit button. The center of the field of view will remain fixed to the center of the geometric bounding box of all the bodies, as visualized. The camera is no longer at rest in World, but continually zooms and pans to track this geometric center.

Controlling Animation

Caution With automatic tight fit enabled, the observer’s reference frame is no longer at rest in World and, in general, is noninertial. The motion of bodies thatyouseeisnotthatseenbyanobserverinWorld.

This autom atic tight fit can create the illusion that the bodies as a whole are not moving. Disable the automatic tight fit to check if this is the case.

Changing How the Animation Is Updated

You might find it convenient to change how quickly the animation in the display window responds to changes in the simulation, especially if the animation is going by to o fast in real (clock) time.

You can change most of these con trols by going to the Simulation menu in themenubar,thentoControl Animation Speed. The Animation Speed Control Parameters dialog box opens. You can apply any changes and close the dialog by clicking OK.

Delaying the Simulation at Every Display Update

At each update of the animation display, the SimMechanics simulation is delayed for some (simulated) time to allow you to follow the motion. You can change this delay time in the Animation Speed Control Parameters dialog. Enter a nonnegative time (in milliseconds) in the Delay per frame field. The default is

3 (ms).

Changing the Visualization Sample Time

You can break the default connection between visualization and model output sample times in the Animation Speed Control Parameters dialog as well. Enter a specified visualization sample time (in seconds) in th e Visualization sample time field. This time is simulated (not real) time.

The default is time, and the visualization is effectively updated at the output sample times.

Require the visualization explicitly to inherit the model output sample time by entering

0 (s). This is smaller than any positive model output sample

-1.

2-25

2 Getting Started with the Visualization Window

Changing the Model Output Sample Time

You can also change the effective visualization sampling rate by changing the model output sample time in the model’s Configuration Parameters dialog and leaving the visualization sample time to be whatever the model output sample time is. This time is simulated (not real ) time.

1 Open the Configuration Parameters dialog from the Simulation menu of

your model window.

2 On the Data Import/Export node, in the Save options area, change the

Output options pull-down menu entry to

only

3 Use the Output times field on the right to specify explicitly how often

Simulink should capture the simulation output. In this field, enter a vector ofsampletimes.Thesampletimerangemustbethesameasorliewithin the Start time and Stop time range of the Simulation time area in th e Solver node of Configuration Parameters.

Produce specified output

2-26

If you want a uniform output sampling, use the

linspace command to specify

thetimerangeandnumberofsamplepoints:

linspace(start-time, end-time, number-of-points)

Forexample,tosample200pointsfrom0to10seconds:

1 Open Configuration Parameters f rom the Simulation menu.

2 Locate Output options in the Data Import/Export node. Change the

pull-downmenuto

3 Enter linspace(0,10,200) in the Output times field. Click Apply or OK.

Produce specified output o nly.

Tip This approach does change two distinct model features at once. Changing the visualization sample time by itself (preceding) has the advantage of letting y ou specify the model output sample time separately.

See the Simulink documentation for more about model output sample time.

Controlling Animation

Speeding Up the A

As the simulatio make the animati

n animates the bo dies’ motions, it might slow down. You can

on computationally less demanding with these measures.

nimation in Real Time

Skipping Frames

By default, th fixed number o

From the Simu Animation Sp

frames per u

default is

Using fewe simulatio

e animation displays every updated frame. But you can skip a

f frames between displayed frames.

lation menu, select Control Animation Speed.Inthe

eed Control Parameters dialog, change the Number of skipped

pdate field to a positive integer to specify this number. The

r sample points leads to a more disjointed animation, but a faster

n and a smaller recorded animation file.

Turning Off Visualization Features

You can sp

• Body cen

• Body coo

eed up the animation if you turn off one or both of these symbols:

ters of gravity (CGs)

rdinate systems (CSs)

The pre page 2-

You ca displ the Vi

ceding section, “Controlling Body and Body Component Display” on

6, explains how to control their display.

nalsospeeduptheanimationbyturning off the simulation time

ay. See the preceding section, “Controlling and Timing Simulation from

sualization Window” on page 2-21.

2-27

2 Getting Started with the Visualization Window

Recording Animation

In this section...

“About Recording” on page 2-28

“How Recording Works” on page 2-28

“Recording Animations” on page 2-28

“Compressing Animation Recordings” on page 2-30

“Controlling the Size of the Recorded Animation” on page 2-31

“Playing Recordings of Animation” on page 2-31

About Recording

As the SimMechanics visualization window displays the body motion, you can capture what you see as a recording and save it. This section explains how to record animations. See the preceding section, “Control li ng Animation” on page 2-23, for more about animation.

2-28

How Recording Works

If you record an animation, the recording captures e ach updated, displayed simulation scene as a frame.

Whatever you see in the animated display window, is what the recording captures, as closely as it can within the limitations of the format.

Recording Animations

When you record an animation from the window, it is stored as a file on your system in Audio Video Interleave (AVI) format.

Caution Recording an animation overwrites any existing file with the same name as the AVI file in the same folder. The AVI file write fails if a file of the same name that is locked by another application exis ts in the same folder.

Recording Animation

Activating and Controlling Animation Recording

• You can activate animation recording by clicking the Store Animation in

AVI File button on the toolbar. The default is deactivated.

If you activate, the AVI File L ocation file browser opens, as discussed next.

• You control recording settings using the Simulation menu.

Specifying the Name and folder of the Animation File

You can specify a location and name for your AVI file recording by selecting Choose AVI File Location from the Simulation menu. If you activate recording, an AVI File Location file browser opens and requires you to select a location and specify an AVI name. The default AVI name for a model called

modelname.mdl is modelname.avi, bu t you can change this default name.

Click Save to complete the AVI file specification.

When you activate recording, this AVI file name appears in the bottom middle of the full visualization window, below the display, in the status bar.

If y ou cancel the file browser, the recording is canceled as well.

2-29

2 Getting Started with the Visualization Window

2-30

How MAT

The simulation first records a MATLAB movie by capturing the display at every visualization sample time step. Then, in the termination phase of your simulation, it converts this movie to AVI format and stores it in the AVI file. A small AVI Conversion window opens to indicate that conversion and storage are complete and to display the path of the AVI file. Click OK to close this prompt.

LAB Records the Animation

Compressing Animation Recordings

You can reduce the size of your AVI file by compressing it. Select Compress AVI File to activate this feature. The default is active.

Recording Animation

Support Restrictions for Recording Compression

AVI compression is available only on the Windows®platform. MATLAB uses the Indeo 5 compression algorithm. You must have the corresponding video codec installed to

• Compress an animation while recording.

• Decompress and play back a compressed animation recording.

Check your operating system configuration for installed video codecs.

Caution YoumusthavetheIndeo5videocodecinstalledtocompressan animation recording. If you do not have this codec installed, a nimation and recording proceed, but with compression deactivated.

Controlling the Size of the Recorded Animation

Any technique that reduces the number of visualization samplings and updates reduces the total stream of animated frames and the size of the recorded file. See “Controlling Animation” on page 2-23.

Tip If MATLAB runs out of memory while recording an animation, you will receive a warning. The simulation continues until completion, but recording is truncated at the simulation time when memory was exhausted.

Useoneofthetechniquesdiscussedtoreducethetotalstreamofanimated frames and attempt the recording again. The simplest technique is to skip frames.

Playing Recordings of Animation

You need an AVI-compatible video player to view the recorded file. You can use the internal MATLAB movie viewer or an external video player.

2-31

2 Getting Started with the Visualization Window

Caution You must have the Indeo 5 video codec installed to decompress and

play back a compressed animation recording.

Matching Playback Speed to Simulation Speed

Your computer will play back an AVI animation recording at 15 frames per second of real (clock) time, regardless of the simulation speed or visualization sample time during recording.

To guarantee that the animation playback show the simulation in real (clock) time, before recording, set:

• The model output sample time to be 1/15th of a second.

• The visualization sample time to be equal to or less than the model output

sample time.

See “Changing How the Animation Is Updated” on page 2-25 for more about sample times.

2-32

Visualization Menus and Their Controls

In this section...

“About the SimMechanics Visualization Window Menus” on page 2-33

“View Menu” on page 2-34

“Simulation M enu” on page 2-35

“Model Menu” on page 2-38

“Help Menu” on page 2-39

About the SimMechanics Visualization Window Menus

The m enus of the visualization window group similar functions and contain all visualization functions.

Some menu items have a default setting. Others do not, as indicated by a “—” entry for the default in the menu tables following.

Visualization Menus and Their Controls

Menu Group Featur

View

ation

Simul

Model

Help

rsistent Settings Versus Immediate Action

In most situations, all menu items are enabled in the sense that you can activate it. In some conditions, a menu item can be disabled, and you cannot activate it.

Change view;

Contr anima

Chan comm

Get

eorFunction

camera viewpoint or frame; manipulate camera

change background

ol simulation; change dynamic camera response to

tion; record animations

ge dis play of body components and geometries; change

on visualization-model features

visualization help

2-33

2 Getting Started with the Visualization Window

Some menu items control a persistent setting and switch between active and not active; for example, Enable Model Highlighting. By selecting the item, you either activate it, and a check mark appears; or you deactivate it, and the check m ark disappears.

Othermenuitems,whenyouselectthem,insteadtriggeranimmediate action, for example, Simulation > Start.

View Menu

This menu allows you to control two distinct visualization features, the camera viewpoint and frame and the background color.

2-34

Menu Item

Orientation

submenu:

Front, Back, Top, Bottom, Left, Right, Isometric

Fit to View

Function

Set camera viewpoint. Onechoiceisalwaysactive,andthe choices are mutually exclusive.

Resize camera field to closely fit the bodies as viewed. Applies immediately.

Default

Front

—

Visualization Menus and Their Controls

Menu Item

Current Tool:

Select Select objects in the display window. Selected

Rotate

Pan

Zoom

Change Background Color

Function

Enable mo us e point-and-click tool. The choices are mutually exclusive, and can all be unselected (deactivated).

Rotate camera viewpoint. Unselected

Pan camera field laterally and vertically.

Zoom in and out of camera field.

Open color palette to choose background color.

Default

—

Unselected

—

Simulation Menu

Thismenuallowsyoutocontrolthesimulation,thedynamiccamerafield, and the recording of the animation.

2-35

2 Getting Started with the Visualization Window

Menu Item

Simulation start, pause, and stop

Dynamic camera field Enable adaptive dynamic cam era field

Start Start simulation. Appears and enabled

Pause

Stop Stop simulation. Enabled only when

Enable Automatic Tight Fit

Enable Automatic Expanding Fit

Function

only w hen simulation is stopped. Applies immediately. Keyboard equivalent is Ctrl+T.

Pause simulation. Appears and enabled only w hen simulation is running. Applies immediately.

simulation is running. Applies immediately. Keyboard equivalent is Ctrl+T.

during animation. The choices are mutually exclusive, and can all be unselected (deactivated).

Enable automatic resizing and zooming of camera field to keep moving bodies in fit-to-view field at all simulation times. Virtual camera moves with overall model motion with respect to World.

Enable automatic expansion of camera field to keep moving bodies in field at all simulation times. Virtual camera remains at rest w ith respect to W orld.

Default

—

Fixed camera field, viewpoint, and zoom; camera at rest in World.

Unselected

Store in AVI File Record and save animation in AVI file.

Choose AVI File Location

Compress AVI File Apply compression to saved AVI recording

Choose nondefault location for AVI file. Default location

of animation.

2-36

Unselected

for saved AVI file is current working MATLAB folder.

Selected

Visualization Menus and Their Controls

Menu Item

Control Animation Speed

Display Simulation Time Show simulation time in lower-right corner

Function

Opens Animation speed control parameters dialog. Applies immediately.

of full w indow.

Start–Pause–Stop Menu During Simulation

During simulation, the start–pause–stop part of the Simulation menu looks like this:

Default

Visualization sample time (s)

Delay per frame (ms)

Number of skipped frames per update

Selected

Animation Speed Control Parameters Dialog

The Control Animation Speed m enu item opens the Animation Speed Control Parameters dialog:

2-37

2 Getting Started with the Visualization Window

See “Controlling Animation” on page 2-23.

Model Menu

This menu allows you to control the display of body geometries and body components, as well as communicate from the visualization window to the model.

2-38

Visualization Menus and Their Controls

Menu Item

Body Geometries

submenu:

Convex Hulls

Ellipsoids Visualize all bodies in window as equivalent ellipsoids. Unselected

Individual Body Setting

Centers of G (CGs)

Coordinat (CSs)

Update Si Diagram

Enable Model Highlighting

Save Visualization Settings to Model

ravity

eSystems

mulink

Function

Set geo metries of visualized bodies. One choice is always active, and the choices are mutually exclusive.

Visualize all bodies in window as convex hulls. Unselected

Visualize al

respective B

Display cen

Display all Body coordinate systems attached to all visualized bodies.

Apply Upd immedia Keyboar

Edit > Up

Enable automatic Body block h ig hlighting when visualized body is selected in display window.

Save current state of visualization window controls to model. Applies immediately. (You need to save the m odel itself to save the settings permanently.)

l bodies in window according to their

ody block visualization settings.

ters of gravity of all visualized bodies.

ate Diagram command to m odel. Applies

tely.

dequivalentisCtrl+D. Model equivalent is

date Diagram.

Default

—

Selected

—

Select

—

Help Menu

This menu allows you to get online help for the visualization window. Selecting Open Visualization Help immediately opens the Help browser to the SimMechanics visualization documentation.

2-39

2 Getting Started with the Visualization Window

2-40

Customizing Visualization and Animation

You can customize the colors and geometries of visualized bodies in the SimMechanics visualization window. Choice of colors is intrinsic to visualization. Specifying a custom body geometry requires an external graphics file for each custom ized body.

As an alternative to the visualization window, you can also visualize your mechanical system with virtual reality.

• “About Custom SimMechanics Visualization” on page 3-2

• “Customizing Visualized Body Colors” on page 3-4

• “Customizing Visualized Body Geometrie s ” on page 3-7

• “Visualizing with a Virtual Reality Client” on page 3-13

3 Custom izing Visualization and Animation

About Custom SimMechanics Visualization

In this section...

“Customizing Visualization Settings” on page 3-2

“Creating an External Virtual Reality Client” on page 3-3

Customizing Visualization Settings

You can customize the way that SimMechanics visualization displays bodies, in terms of their colors and geometry. The geometry is composed of the body’s size and shape.

• You can adjust the body color on a model- or machine-wide basis, or on an

individual body basis.

• With an external graphics file referenced by a Body block, the visualization

window can visualize the body with whatever shape the graphics file specifies.

3-2

Starting visualization is discussed in

• Chapter 1, “Introducing Visualization and Animation”

• The SimMechanics User’s Guide

Model- and Machine-Wide Body Color and Geometry Controls

The model–machine–body hierarchy controls the model- and machine-defau lt body colors and geometries. See “Hierarchy of Body, Machine, and Model Visualization Settings” on page 1-11.

To control visualization settings for an entire model or machine, you need to revisit the follow ing two dialogs. These controls a llow you to set a single default color and a single default standard geometry for all the bodies in a model or in a machine.

• To set a model-wide default b ody color and geometry, use the Visualization

area of the SimMechanics node of the Configuration Parameters dialog.

About Custom SimMechanics™ Visualization

• To set machine-wide default body color and geometry, use the

Visualization tab of that machine’s Machine Environment block dialog.

Creating an External Virtual Reality Client

You can bypass standard SimMechanics visualization by creating a virtual reality world of your own design to visualize your model’s bodies. You can then build a custom interface from your model to the virtual world and animate its virtual bodies. See the final section, “Visualizing with a Virtual Reality Client” on page 3-13.

3-3

3 Custom izing Visualization and Animation

Customizing Visualized Body Colors

In this section...

“Choosing Custom Body Colors” on pag e 3-4

“Switching Betw ee n Default and Custom Body Colors” on page 3-4

Choosing Custom Body Colors

SimMechanics visualization has two formats for specifying a color.

MATLAB ColorSpec Vector

You specify colors by RGB values according to the MATLAB Graphics

ColorSpec for

• An entire model, in the Visualization area of the SimMechanics node of

the Configuration Parameters dialog.

3-4

• An entire machine, in the Visu alization tab of that machine’s Machine

Environment block dialog.

The RGB (red–gre en–blue) triple of values is a vector value separately satisfying 0 ≤

• Red, green, and blue are

• Black and white are

• Other valid triples specify nonfundamental colors.

[0 0 0] and [1 1 1],respectively.

r, g, b ≤ 1.

[1 0 0], [0 1 0],and[0 0 1],respectively.

[r g b],witheach

Color Palette Interface

You specify colors for individual bodies by visual inspection in the color palette in their respective Body dialogs.

Switching Between Default and Custom Body Colors

The SimMechanics visualization initial default color for visualized bodies is red (RGB of

[100]).

Customizing Visualized Body Colors

Changing the Default Color for All Bodies in a Model

You can change the initial default to a different default color for all visualized bodies in a model.

1 Open the Configuration Parameters dialog, then go to the SimMechanics

node.

2 In the Visualization area, change the Default body color RGB vector to

a different, valid vector of values.

3 Click Apply or OK.

Note You can override the model-wide default body color, both for a whole

machine and for individual bodies.

Changing the Default Color for All Bodies in a Machine

The initial default is for a machine to inherit its model-wide body color. You can override the initial default by specifying a different machine-wide default color for all the bodies in one machine in your model.

1 Open that machine’s M achine Environment block dialog and click its

Visualization tab.

2 In the Body color selection mode pull-down menu, choose Specify.The

Default body color field becomes active .

3 Change the RGB vector to a different, valid vector of values.

4 Click Apply or OK.

Note You can override the machine-wide default body color for any

individual body within the machine.

3-5

3 Custom izing Visualization and Animation

Changing the Color of an Individual Body

The initial default is for a Body to inherit its machine-wide body color. You can override the initial default by specifying a different color for an individual visualized body.

1 Open the Body block dialog and click its Visualization tab.

2 In the Body color pull-down menu, choose Use color palette.Thecolor

palette button appears.

3 Click the color palette button. The color palette opens.

4 Select a color from the palette and click OK.

5 To save the changes to the Body block and the model, click OK on the

Body dialog.

Body Dialog: Visualization Tab and Body Color Palette

3-6

Customizing Visualized Body Geometries

In this section...

“Choosing Custom Body Geometries” on page 3-7

“Switching Betw een Standard Body Geometries” on page 3-7

“About STL Body Graphics Files” on page 3-8

“Obtaining STL Body Graphics Files for Custom Body Geometries” on page 3-9

“Switching Between Standard and Custom Body Geometries” on page 3-10

Choosing Custom Body Geometries

Using body mass and geom etry information from the Body block alone, the SimMechanics visualization window allows you two choices of standard body geometry, the convex hull and the equivalent ellipsoid.

Customizing Visualized Body Geometries

You also have the choice of a nonstandard body geometry specified by an external graphics file.

Switching Between Standard Body Geometries

The SimMechanics initial default body geometry for visualized bodies is the convex hull.

Changing the Default Geometry for All Bodies in a Model

You can change the initial default of convex hulls to equivalent ellipsoids for all visualized bodies in a mo de l.

1 Open the Configuration Parameters dialog, then go to the SimMechanics

node.

2 In the Visualization area, select Equivalent ellipsoid from mass

properties

ick Apply or OK.

3 Cl

from th e Default body geometries pull-down menu.

3-7

3 Custom izing Visualization and Animation

Note You can override the model-wide default body geometry, both for a

whole machine and for individual bodies.

Changing the Default Geometr y for All Bodies in a Machine

The initial default is for a machine to inherit its model-wide body geometry. You can override the initial default by specifying a different machine-wide default geometry for all the bodies in one machine in your model.

1 Open that machine’s M achine Environment block dialog and click its

Visualization tab.

2 In the Default body geometries pull-down menu, choose a new

machine-wide default, either

Equivalent ellipsoid from mass prop erties.

3 Click Apply or OK.

Convex hull from body CS locations or

3-8

Note You can override the machine-wide default body geometry for any individual body within the machine.

Changing the Geometry of an Individual Body

The initial default is for a Body to inherit its machine-wide body geometry. You can override the initial default by specifying a different geometry for an individual visualized body.

1 Open the Body block dialog and click its Visualization tab.

2 In the Body geometry pull-down menu, choose either Convex hull from

body CS locations

3 Click Apply or OK.

or Equivale nt ellipsoid from mass properties.

About STL Body Graphics Files

SimMechanics visualization supports the specification of body geometry (size and shape) with stereolithographic (STL) files in either ASCII or binary

Customizing Visualized Body Geometries

format. Each body with a custom geometry requires one STL file to provide this geometry.

Stereolithography specifies the three-dimensional surface geometry of a body by linked triangles whose edges and vertices are oriented by the right-hand rule. The orientation defines an “outside” and an “inside” of the surface. The edges and vertices of the elementary triangles join to form a continuous surface. A closed surface of such linked triangles approximates a body’s smooth curved surface.

Stereo hulls syste can sp at ar the B

Obt Geo

You

lithographic triangles have some similarity to convex hulls . But convex

are directly and solely determined by the origins of the Body coordinate

ms. Convex hulls are not n ecessarily made up of triangles. An STL fil e

ecify an arbitrary number of elementary oriented triangles with vertices

bitrary points in space. These vertices have no necessary connection to

ody coordinate systems.

aining STL Body Graphics Files for Custom Body

metries

can obtain STL body geometry files from a number of sources.

3-9

3 Custom izing Visualization and Animation

• You can write a new STL file as a text file, following the STL standard.

• You can generate an STL file from many mechanica l design applications,

such as computer-aided design (CAD) platform s.

• The SimMechanics Link utility exports an STL file for each part in a CAD

assembly. The CAD platform must be linked to the SimMechanics Link utility.

• You can reuse existing STL files, possibly with your own modifications. You

can obtain such STL files from SimMechanics demos, other applications, and CAD-oriented Web sites.

Note Refer to the SimMechanics Link documentation for more information about exported STL files.

Switching Between Standard and Custom Body Geometries

You can switch from the standard body geometries to a custom body geometry by changing the Body block to reference a n external body geometry file. This custom body geometry specification overrides the model- and machine-wide defaults, but only for this body.

3-10

Requirements for External Body Geometry Files

The external body geometry file must be in STL format.

Caution In order for custom visualization to work, this STL file must be either:

• On your MATLAB path.

• In your MATLAB present working folder.

• SpecifiedwithcompletepathintheBodydialog.

Otherwise, visualization reverts to the default body geometry.

Customizing Visualized Body Geometries

Specifying an External Body Geometry File

1 Open the Body block dialog and click its Visualization tab.

2 In the Body geometry pull-down menu, choose External graphics file.

The External graphics file field and Attached to Body CS pull-menu appear.

3 Enter the graphics file name and any necessary path in the field.

4 From the pull-down menu, choose which Body CS to attach the graphics

to. (The Body CSs are listed in the Body’s Position tab.) This Body CS serves as the reference for the origin, coordinate axes, and units of the body geometry.

5 Click Apply or OK.

Body Dialog: Visualization Tab and External Body Geometry Reference

Attached Body Coordinate System as Geometric Reference for the B

The external graphics file has no intrinsic geometric origin, orientation, or units. The attached Body CS provides an origin, axis d irections (orientati o n), and units of length to interpret the geometric information specified by the external graphics file.

ody Geometry File

3-11

3 Custom izing Visualization and Animation

Tip If you need a body geometry origin, orientation, or system of units that is

not represented in your current list of Body coordinate systems, create a new Body CS in the Position tab with the geometric features you want. You can make this Body CS invisible on the Body block if you wish.

3-12

Visualizing with a Virtual Reality Client

In this section...

“About Virtual Worlds for Machines and Models” on page 3-13

“Creating Virtual Worlds for SimMechanics Models” on page 3-13

“Interfacing SimMechanics Models with Virtual Worlds” on page 3-18

“Reference” on page 3-27

About Virtual Worlds for Machines and Models

You can bypass SimMechanics visualization and create a mechanical animation in a virtual world of your own design. You create a virtual world, populate it with bodies represented as virtual objects using Virtual Reality Modeling Language (VRML), then interface the virtual world with your SimMechanics model. Creating your own virtual animation requires a new or existing virtual world for your model and an interface between them.

Visualizing with a Virtual Reality Client

This section explains how to couple a separately created virtual world with a SimMechanics model.

Building Virtual Worlds This section assumes that Simulink®3D Animation™ software is installed on your system and that you are familiar with it and with creating virtual worlds. Refer to the Simulink 3D Animation documentation for full details on installing and using this toolbox.

We recommend you allocate generous central processor power, graphics card speed, and memory for virtual reality visualization , especially for animation.

Creating Virtual Worlds for SimMechanics Models

The Simulink 3D Animation documentation and VRML books [1] explain how to create virtual objects and assemble them into virtual worlds. A displayed virtual world is called a virtual scene. The best way to become comfortable moving around in a virtual world is to practice with a variety of movement modes and viewpoints. This section highlights the requirements to m ake a virtual world usable as a visualization for a SimMechanics model.

3-13

3 Custom izing Visualization and Animation

Editing Virtual Worlds and VRML Files

As you create a virtual world populated by virtual bodies, you must create each component body, then plan and implement the geometry of the bodies’ initial s tate. Use a VRML authoring tool that can read VRML as a native format to create and edit virtual reality software includes a VRML authoring tool called V-Realm Builder familiar with native VRML source code, you can use a plain text editor or the MATLAB editor to edit the files.

Representing Bodies as Virtual Objects

You represent each body by a virtual object encoded in a .wrl file. You also create a master

.wrl files, placing and orienting these bodies in the larger scene. You can

define a body’s position and orientation wit h respect to:

• The overall virtual world, corresponding to the SimMechanics coordinate

system World.

• Another body in the machine, corresponding to SimMechanics Body

coordinate systems.

.wrl files. Simulink 3D Animation

.wrl file to represent the virtual world that refers to body

.Ifyouare

3-14

You can nest body references to other bodies in VRML hierarchies, but you must define at least one body’s position and orientation with respect to the overall virtual world. Place and orient the bodies in their initial states, corresponding with the initial state of the SimMechanics simulation.

Each body’s node. Among Transform’s fields must be translation and rotation fields to specify the body’s position and orientation in space. If a body is nested below another body, its position and orientation are defined with respect to the next body up the hierarchy.

Creating your own virtual world gives you great flexibility in representing your machine:

• Youcandisplaybodiesinasmuchoraslittledetailasyouwant,with

shapes, colors, textures, etc., of your own choosing.

• You can include or omit bodies as desired.

.wrl file contains a hierarchical tree starting with the Transform

Visualizing with a Virtual Reality Client

• You can create a computer-aided design (CAD) assembly of your machine

andexportitintoVRMLfiles.

• If you only translate a body, you can omit the rotation field from its

Transform node.

• If you only rotate a body, you can omit the translation field from its

Transform node.

Example: Viewing Custom External VRML Files for the Conveyor Loader

Thedemomodelmech_conveyor_vr is a modified version of the original conveyor model containing static geometries of the machine parts in their initial positions. This e xample uses the V-Realm Builder editor to view the files.

1 In the matlabroot\toolbox\physmod\mech\mechdemos \ folder, open these

external VRML files with V-Realm Builder:

base.wrl, convmech.wrl, link1.wrl, link2.wrl, link3.wrl, link4.wrl, pusher.wrl

mech_conveyor and comes with external VRML files

2 With the convmech.wrl world in focus, click the Test Mode button in

the V-Realm Builder toolbar and view the complete machine in the Main

3-15

3 Custom izing Visualization and Animation

view. Right-click in this window to configure the navigation. If the colors seem washed out, disable the headlight.

3-16

Visualizing with a Virtual Reality Client

3 OntheleftsideofyourVRMLeditor window, examine the node tree

convmech.wrl that refers to the six VRML files representing each

component body:

The hierarchy of body position and orientation references is flat in this model. Each body is separately referenced to the top level of the hierarchy,

New World.

3-17

3 Custom izing Visualization and Animation

4 Expand one of the nodes. Each body node has, among others, rotation

and translation fields:

3-18

The exception is the base. Being grounded and immobile, it has neither a translation nor a rotation field.

Interfacing SimMechanics Models with Virtual Worlds

To animate a body, you need to measure its motion in your SimMechanics simulation and export that information to the virtual world. This requires connecting Body Sensor blocks to the Bodies you want to animate in your model, then creating an interface that animates the virtual bodies with the body sensor motion signals. “Example: Interfacing the Conveyor Loader Model a nd Virtual World” on page 3-21 applies these steps to the

mech_conveyor_vr demo.

Adding and Configuring Body Sensors

Refer to the SimMechanics User’s Guide for general information on how to use Body Sensors. Connect the Body Sensors to Body coordinate systems (CSs)

Visualizing with a Virtual Reality Client

on the bodies whose motions you want to animate. The Body block reference discusses how to create and configure Body CSs. You need to take these extra steps to export the signals of a body sensor to your virtual world:

1 Make sure the Body Sensor’s Body CS reference origin and orientation

follow the body’s defining VRML hierarchy.

Example: You define a new Body CS on a body to connect the Body Sensor. If you defined the VRML body’s position with respect to the center of gravity (CG ) of a second, neighboring body in your VRML files, you should set the Translated from origin of field of the new Body CS to the origin of the CG CS of the second body.

2 In the Body Sensor dialog, select the [x;y;z]Positioncheck box if you

want to animate the body’s translational motion.

Select the [3 x 3] Rotation matrix check box if you want to animate the body’s rotational motion.

3 Choose the coordinate system in which the body motions are measured in

the With respect to coordinate system pull-downmenu. Youcanpick

Absolute (World) or Local (Body CS). This coordinate system should

be the same as the coordinate system used to define the body’s position and orientation in the VRML files.

A Simulink output port

> appears on the block for each o f the motio n signals.

The translational signal is a 3-vector of spatial coordinates, (x,y,z).The rotational signal is a 9-vector, column-wise representation of the 3-by-3 orthogonal rotation matrix R, (R

11,R21

, R31, R12, ...).

Animating the Virtual World Bodies

Animating the virtual bodies requires interfacing the body sensor signals in the SimM echanics model with the VRML translation and/or rotation fields in the

.wrl files. Yo u accomplish this with the VR Sink block, which you can

find in the Simulink 3D Animation block library.

1 Enter vrlib at the command lin e. Drag a copy of the VR Sink block into

your model.

3-19

3 Custom izing Visualization and Animation

2 Open the VR Sink dialog box. (The figure Conveyor Loader Model: VR Sink

Dialog Box on page 3-26 displays an example of the dialog.)

3 In the Source file field in the World properties area, enter the name

of the VRML file that represents your model’s virtual world. This is the file that refers to the other yourmachine. IfthevirtualworldVRMLfileisnotinthesamefolderas your model, enter the file’s path relative to the model.

Click Apply.IntheVRML Tree window, the node list of the virtual world

.wrl file appears.

4 Expandthetreeofeachcomponentbodyinthelisttoviewthatbody’s

check box list. Select the rotation and/or translation check boxes as needed for each body. A Simulink input port each of these selected check boxes.

.wrl files representing the component bodies of

> appears on the block icon for

The ports are labeled

field is named either rotation or translation.

node.field.Thenode is the nam e for the body. The

Converting Body Sensor Signals into VRML Format

You are now ready to connect the Body Sensor output signals to the VR Sink block. But you might need to modify those signals for valid use in VRML.

• You can connect the translational motion signal line directly from the

output port of the Body Sen sor to the VR Sink. The VRML node tree directly accepts translation motion as a 3-vector signal of rectangular coordinates (x,y,z).

Make sure that the translational motion signal refers to the same coordinate system used to define the body’s positio n in the VRML files.

• You cannot directly connect the rotational motion signal line to the VR

Sink. The Body Sensor output represents orientation with a 3-by-3 rotation matrix R, while VR ML accepts orientation represented as the axis-angle 4-vector form [ n θ ], where n = (n rotation axis and θ is the rotation angle.

Open the SimMechanics U tilities library. For each rotational motion signal, drag a Ro tationMatrix2VR block into your model. Connect the rotation signal from the Body Sensor block to the RotationMatrix2VR

node.translation inputportonthe

, ny, nz) is a 3-vector representing the

3-20

Visualizing with a Virtual Reality Client

block. Then connect the latter block to the corresponding node.rotation input port on VR Sink for that body. This block converts the 3-by-3 R matrix signal into the 4-vector VRML form.

Close the VR Sink block dialog. Your SimMechanics model now animates the virtual world.

Example: Interfacing the Conveyor Loader Model and Virtual World

In the mech_conveyor_vr demo model, open the Body Sensor1 block. The block measures the translational and rotational motion of Link3 in the conveyor:

Body Sensor1 block has two Simulink output signals.

The

3-21

3 Custom izing Visualization and Animation

The other Body Sensor blocks are similar, except for Body Sensor2, w hich measures only the translational motion of the pusher. All the Body Sensors measure body motions with respect to World, the frame in which the conveyor base is at rest. Each motion signal represents the body’s displacement relative to its initial position.

3-22

Visualizing with a Virtual Reality Client

The mech_conveyor_vr model contains a Simulink 3D Animation subsystem interfacing to the model’s custom VRML files. The interface is routed through the

mech_conveyor_vrlib custom library.

Conveyor Loader Model with Custom Virtual Reality Animation I nterface

3-23

3 Custom izing Visualization and Animation

Custom Virtual Reality Animation Interface Subsystem

3-24

1 Trace each body sensor signal. The signals are routed through pairs

of Simulink Goto blocks (in the model) and From blocks (in the custom library).

Visualizing with a Virtual Reality Client

2 Open the Simulink 3D Animation subsystem. The VR Sink block in the

custom library and the virtual scene viewer open, displaying the conveyor machinescene. ThesceneissimilartothatvisibleintheVRMLeditor (see “Example: Viewing Custom External VRML Files for the Conveyor Loader” on page 3-15).

Conveyor Loader Model: Simulink®3D Animation™Viewer

3 From the menu bar of the virtual scene viewer, select Simulation,then

Block Parameters. The VR Sink block dialog opens.

The Source file is

convmech.wrl, the master file for this virtual world.

The VRML Tree on the right reproduces the nodetreevisibleintheVRML editor for

convmech.wrl.

3-25

3 Custom izing Visualization and Animation

3-26

Conveyor Loader Model: VR Sink Dialog Box

4 Expand and scroll down the VRML trees. The trees for Link1, Link2,

Link3, Link4, and Pusher list the field inputs for accepting motion signals.

• The Link component bodies require both translational and rotational

motions. All the Links have actively selected check boxes for their rotation and translation field inputs.

• The Pusher body requires only translational motion. Only the

translation fie ld check box is selected for the Pusher.

Visualizing with a Virtual Reality Client

Each of the nine Simulink input ports on the VR Sink block is named

node.field. The Base o f the conveyor does not move, so its node has no

motion input fields.

5 If you closed the Simulink 3D Animation viewer, you can reopen it from

the VR Sink dialog. Click View in the World properties / Source file area of the dialog.

6 Close all the dialog boxes by clicking OK, leaving the viewer open.

7 Click the Start buttoninthemodelwindow.

As in the original

mech_conveyor demo, starting the model opens the

Reference Position slider bar that you can move from side to side. As you do so, watch the pusher in the viewer move in parallel.

Reference

[1] Marrin, C., and B. Campbell, Teach Yourself VRML 2 in 21 Days, Indianapolis, Indiana, Sams, 1997.

3-27

3 Custom izing Visualization and Animation

3-28

Importing Mechanical Models

Using SimMechanics software w ith computer-aided design (CAD) extends your mechanical modeling and simulation capabilities, allowing you to create SimMechanics models from CAD assemblies. This chapter covers what you need to get started with CAD translation. It assumes some familiarity with SimMechanics modeling, as e xplained in the SimMechanics Getting Started Guide and SimMechanics User’s Guide.

• “Introducing Mechanical Import” on page 4-2

• “Generating New Models from Physical Modeling XM L” on pag e 4-6

• “Working with Generated Models” on page 4-12

• “Updating Generated Models Using Physical Modeling XML” on page 4-22

• “Controlling Model Update at the Block Level” on page 4-32

• “Troubleshooting Imported and Updated Models” on page 4-46

4 Importing Mechanical Models

Introducing Mechanical Import

In this section...

“About Mechanical Import and CAD Translation” on page 4-2

“Requirements for CAD E xport and Me chanical Import” on page 4-3

“Essential CAD Translation Steps” on page 4-4

About Mechanical Import and CAD Translation

SimMechanics software features an importer that lets you automatically generate SimMechanics models from an XML file in Physical Modeling format. This externally defined XML file specifies mechanical information — bodies, degrees of freedom, and geometry — in a form that the SimMechanics importer can use to construct a model representing that system.

The standard way to obtain such a Physical Modeling XM L is to generate it by exporting a computer-aided aided (CAD ) assembly. CAD tools allow you to model mechanical systems geometrically as collections of parts, or assemblies. You use Simulink and SimMechanics block diagrams to represent control systems composed of mechanical devices and simulate their dynamics. The block diagram approach does not include full geometric information, nor do CAD assemblies typically incorporate controllers or allow you to perform dynamic simulations. With CAD translation, you can combine the power of CAD and SimMechanics software.

4-2

The SimMechanics Link utility is the nece ssa ry intermediary that lets you convert CAD assemblies into SimMechanics models. The intermediate step between CAD assembly and SimMecha n ics model is exporting an XML file in Physical Modeling format from the assembly. The export also automatically creates STL files containing body geometry information that you need for visualizing the bodies in the model.

The SimMechanics importer then converts this XML file into a mechanical model, which refere n ces the STL files to visualize the bodies.

Complete Translation of CAD Assembly Into a Visualizable Model

Requirements for CAD Export and Mechanical Import

The full CAD translation is composed of two distinct steps, with different requirements.

1 The first step is the e xport of the CAD assembly, which creates the Physical

Modeling XML file and one or more STL file(s).

Introducing Mechanical Import

2 The second step is the import of the Physical Modeling XML file and

generation of the SimMechanics model.

CAD Export Software Requirements

To export a CAD assembly into XML, you mu st first

1 Install your CAD platform or software application.

2 Install the SimMechanics Link utility and link it to your CAD platform.

The SimMechanics Link utility requires MATLAB only.

Note For CAD export, you do not need Simulink or SimMechanics software.

Setting Up SimMechanics Link Software. Learn more about and obtain

the SimMechanics Lin k utility at the MathWorks™ Web site.

4-3

4 Importing Mechanical Models

Physical Modeling XML Import Software Requirements

To import a Physical Modeling XML file and generate a model, you must have installed Simulink and the Simscape™ and SimMechanics products.

Note For XML import, you do not need a CAD platform or the SimMechanics Link utility.

Essential C AD Translation Steps

Converting a CAD assembly to a SimMechanics model requires two major steps, exporting the CAD assembly into XML, then importing the XML t o create a SimMechanics model.

Exporting an Assembly to XML

You export the assembly from the CAD platform into a Physical Mo deling XML file that you can later use with the SimMechanics importer. See the SimMechanics Link User’s Guide.

4-4

ting a CAD Assembly into a Physical Modeling XML File

Expor

Automatic Export of STL Files Representing CAD Part Geometries

When you export the CAD assembly into Physical Modeling XML, the SimMechanics Link exporter also automatically creates an STL body geometry file for each body represented as a CAD assembly part. You then need these STL files for SimMechanics visualization, once you create your SimMechanics model.

Introducing Mechanical Import

See “Referencing STL Body Geometry Files for SimMechanics Model Visualization” on page 4-5.

Importing the XML and Generating a Model

To complete the CAD translation, you convert the Physical Modeling XML file into a SimMechanics model. See “Generating New Models from Physical Modeling XML” on page 4-6.

Importing a Physical Modeling XML File into a Model

Referencing STL Body Geometry Files for SimMechanics Model Visualization

Once you have imported the Physical Modeling XML to create a SimMechanics model, you can visualize the bodies in the model. The generated SimMechanics model automatically references the necessary ST L body geometry files, one for each body, to visualize the bodies with their original CAD assembly shapes.

4-5

4 Importing Mechanical Models

Generating New Models from Physical Modeling XML

In this section...

“About Generated SimMechanics Models Based on CAD” on page 4-6

“Generating a New Model from a Physical Modeling XML File” on page 4-7

“Controlling New Model Import with Nondefault Options” on page 4-8

About Generated SimMechanics Models Based on CAD

Note For complete information on exporting Physical Modeling XML, see

the SimMechanics Link User’s Guide.

A computer-aided design (CAD) assembly can contain enough part and constraint information that you can generate a SimMechanics model consisting of Body and Joint blocks representing the assembly. Once you have exported a CAD assembly into a Physical Modeling XML file, you can generate a SimMechanics block diagram model from this file. A new generated model consists of a single SimMechanics machine, corresponding to an assembly with a sing le root.

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This section shows you how to import the XML file into a SimMechanics model using the command

mech_import, which constructs the model.

Requirements for G enerating Models by Importing Physical Modeling XML

This section assumes that you have the SimMechanics product installed locally or remotely, and that you have:

• The XML file representing a CAD assembly

• Optionally, STL body geometry files associated with the CAD parts

Generating New Models from Physical Modeling XML

To generate the SimMechanics model, you do not need the CAD platform or assembly from which the XML file was exported. You also do not need the SimMechanics Link utility.

Generating a New Model from a Physical Modeling XML File

You generate the CAD-based SimMechanics model using the mech_import command or dialog.

Using the Command Line

To start the model generation from a hypothetical XML file called

cad_assembly.xml,enter

mech_import('cad_assembly.xml')

at the command line. A progress bar appears and is updated as the model is imported.

A Simulink model window opens. The model is populated by Bodies and Joints corresponding to the assembly parts and constraints saved in

cad_assembly.xml. The name of the generated model is the name of the

original assembly file, regardless of the name chosen for the XML file.

Using the Import Dialog

You can also select a Physical Modeling XML file and generate a model from it through the Import Physical Modeling XML dialog. Open it by entering

mech_import at the command line with no arguments. See the mech_import

command reference for complete information about the import dialog. After completing your settings, click OK to start the import.

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4 Importing Mechanical Models

4-8

Controlling New Model Import with Non default Options

You have several options for changing the default import behavior of

mech_import and the Import Physical Modeling XML dialog box. For more

information, see “Nondefault Features in Generated Models” on page 4-15.

Customizing the Generated Model Name

You can specify the name of the generated model in the mech_import command or the import dialog. The default is to accept the assembly name specified in the XML file.

For example, an XML file called the assembly name as CAD_A ssembly. Generating a model from this XML

cad_assembly.xml could internally specify

Mathworks SIMMECHANICS 3 Visualization and Import Guide

Specifications and Main Features

Frequently Asked Questions

User Manual

Introducing Visualization and Animation

About SimMechanics Visualization

Starting SimMechanics Visualization

Enabling Visualization for an Entire Model

Visualizing All Bodies in a Machine

Other Si mMechanics Visualization Controls

Using SimMechanics Visualization

Display Versus Animation

Static Display

Dynamic Animation

About Body Color and Geometry: Default, Standard, and Custom

About Body Color: Default and Custom

About Body Geometry: Default, Standard, and Custom

Standard Body Geometry: Equivalent Ellipsoids

Triangle Inequalities

Ellipsoids with Special Symmetry

Reduced-Dimension Ellipsoids

Example: Simple Pendulum Rod

Standard Body Geometr y: Convex Hulls

Example: Four-Cylinder Engine Crank

Hierarchy of Bod y, Machine, and Model Visualization Settings

Visualized Geometries and Colors from Body Block Settings

Body Block Settings Affecting Body Visualization

Mass Properties

Body Coordinate Systems: Origins and Orientation

Visualization

Visualization Settings in the Machine and Model Hierarchy

Initial Default Settings for a Model

Machine Inheritance of Model-Wide Default Settings

Body Inheritance of Machine-Wide Default Settings

Getting Started with the Visualization Window

Introducing the SimMechanics Visualization Window

About the Visualization Window

Opening and Updating the Visualization Window

Menu Bar Versus Toolbar Controls

Visualization Toolbar and I ts Controls

Toolbar Relationship to the Menus

Controlling Body and Body Component Display

About Body and Body Component Display

Interpreting the Body Display Symbols and Shapes

Body Component Display

Body Surface Display

Changing Body Display Symbols

Changing Body Display Shapes

Adjusting the Camera V iew

Setting the Background Color

Interpreting the Camera Projection, Field o f View, and Viewpoint

Visualization and Orthographic Projection

Camera Field of View, Viewpoint, and Frame Size

World Coordinate System Axes Indicate Orientation Only

Automatically Sizing the Camera Field of View

Automatically Setting a Camera Viewpoint

Actively Controlling the Camera Viewpoint

Results of Rolling t he Mouse with the Viewpoint Controls

ForMoreAbouttheSelectTool

Camera Viewpoint and Mouse Controls

Normal Versus Dynamic Mouse Control

Normal and Dynamic Mouse Control with Left Mouse Button

Communicating with the Model from the Visualization Window

Highlighting Bodies, Body Components, and Body Blocks

Enabling and Disabling Highlighting

Updating the Model Diagram

Controlling and Timing Simulation from the Visualization Window

Starting, Pausing, and Stopping the Simulation

With Simulation Stopped

With Simulation Running

Timing the Simulation

Activating and Deactivating the Simulation Time Display

Controlling Animation

About Animation

How Animation Works

Automatically Adapting the Camera View to the Displayed Motion

Allowing the Field of View to Expand with the Moving Bodies

Keeping the Field of View Limited to the Moving Bodies

Changing How the Animation Is Updated

Delaying the Simulation at Every Display Update