1 © 2012 The MathWorks, Inc.

Multibody Simulation

with SimMechanics

김종헌 과장

Senior Application Engineer

MathWorks

2

Key Points

Provides libraries for

modeling 3D

mechanical systems

Use 3D visualization to

animate simulation results

and explore model

Connect to other

physical domains

and controller

in a single environment

3

Agenda

Example Applications and Tasks

– System level analysis and control design

Building a Model: Scissor Lift

– Custom bodies in MATLAB

– Defining reusable components

– Actuating joints

Exploring the Model

– 3D visualization and animation

Guiding the Assembly

– Specifying state targets

4

SimMechanics Applications

Stewart Platform

Platform positions gripper

to track reference trajectory

– Inverse kinematics module and

controller defined in Simulink

SimMechanics helps you:

– Design controller

Control-loop structure, gains

– Optimize system

Component sizes and

actuator dynamics

5

SimMechanics Applications

Landing Gear

Deploys and retracts

based on input signal

– Includes control system,

actuator dynamics

SimMechanics helps you:

– Determine and refine

actuator requirements

– Test loading scenarios

– Test parameter variations

6

Agenda

Example Applications and Tasks

– System level analysis and control design

Building a Model: Scissor Lift

– Custom bodies in MATLAB

– Defining reusable components

– Actuating joints

Exploring the Model

– 3D visualization and animation

Guiding the Assembly

– Specifying state targets

7

Working with

SimMechanics

Build components

– Predefined solids

– Extrusions defined in MATLAB

Parameterize components

– MATLAB variables

– Custom dialog boxes

Connect with joints

– Sense and actuate

– Guide assembly

8

Modeling a Scissor Jack

Problem: Model a scissor jack

using reusable components

in the Simulink environment.

Solution: Use SimMechanics

to model the mechanical system.

Model:

F C R

x

z

y

9

Agenda

Example Applications and Tasks

– System level analysis and control design

Building a Model: Scissor Lift

– Custom bodies in MATLAB

– Defining reusable components

– Actuating joints

Exploring the Model

– 3D visualization and animation

Guiding the Assembly

– Specifying state targets

10

Defining Bodies in

SimMechanics

Problem: Create realistic

body definitions in SimMechanics

Solution: Combine standard solids

and use MATLAB to define extrusions

Model:

x

z

y

B

S

F R C

11

Defining Parameterized

Parts and Mechanisms

Problem: Create parameterized,

reusable components in SimMechanics

Solution: Parameterize components

using Simulink masks and use MATLAB

expressions to make them reusable

Model:

Width

Radius

Length

Parameterize Reuse

12

Actuating and

Sensing Joints

Problem: Add an actuator

to a scissor lift model

Solution: Actuate a SimMechanics

joint with Simulink or Simscape,

and view the results on a Simulink Scope

Model:

Scissor Lift Actuator

13

Agenda

Example Applications and Tasks

– System level analysis and control design

Building a Model: Scissor Lift

– Custom bodies in MATLAB

– Defining reusable components

– Actuating joints

Exploring the Model

– 3D visualization and animation

Guiding the Assembly

– Specifying state targets

14

Exploring the

3D Model

Problem: Need to see how

mechanism behaves and relate 3D

representation to block diagram

Solution: Review animation and inspect

model with Mechanics Explorer

Model:

1. Select views

2. Save/reload view configuration

3. Replay animation

4. View hierarchy and parameters

5. Save to video file

3

1

4

5

2

15

Agenda

Example Applications and Tasks

– System level analysis and control design

Building a Model: Scissor Lift

– Custom bodies in MATLAB

– Defining reusable components

– Actuating joints

Exploring the Model

– 3D visualization and animation

Guiding the Assembly

– Specifying state targets

16

Guiding the

Assembly

Problem: Not all initial conditions

(angles, positions, velocities, etc.)

are known exactly

Solution: Specify target values with

priorities to indicate if targets should be

met exactly or approximately

Model:

x

z

y

xinit (known)

Θinit (unknown)

Θtarget > 0 xinit

Θtarget < 0 xinit

17

Key Points

Provides libraries for

modeling 3D

mechanical systems

Use 3D visualization

to animate simulation results

and explore model

Connect to other

physical domains

and controller

in a single environment