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Nataliya Mulyar

Laci Posta

Coupling Of Multidisciplinary Models

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Outline

• Introduction: COMM within Bode-RC• Rose-RT• Simulink• Rose-RT and Matlab/Simulink: how to

couple?• State-of-affairs in COMM

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Boderc Project

• Consequences of design decisions can be predicted as early as possible

• System-level decisions can be analyzed

• Trade-offs can be made between functions, price, performance, etc.

Universiteit Twente

Goal: improve multi-disciplinary system design, i.e. combining mechanics, electronics and informatics, such that

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The COMM project

• COMM = Coupling of Multidisciplinary Models• 9- month duo OOTI final project• Started on 1st of December 2003

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Problem Description

Sequential development long development cycle

Parallel development lack of communication btw.disciplines

incorrect assumptions problems during

integration late time-to-market

Possible solution: simulate an embedded system in its intended environment

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COMM Project

The problem of

Coupling of models from different disciplines (M, E, I)

Affects The development of real-time embedded systems

The MCT Is a tool that couples two tools widely used for modeling of software and physical components respectively

That • Helps to detect potential problems earlier• Shortens development time (if used properly)• Provides communication means between multiple disciplines

Focuses on design of Multidisciplinary Coupling Tool (MCT)

Business Case

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Concrete Goals

• Explore possibilities of coupling of tools used in MD modeling – Use Rose-RT and Matlab/Simulink as a concrete case

for coupling

• Get better understanding of coupling: – relation simulation-reality– the notion of time in multidisciplinary modeling

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Simulation

Simulation contains a set of models of one or more dynamical systems and the interaction between those systems and their environment (Jim Ledin).

Simulation advances through time and solves the equations for all models at each point in time.

Model is a physical, mathematical, or other logical

representation of a system/process.

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Simulation

Two basic representation methods of simulation models: The discrete event simulation, where time

is moving forward from one change of state to the next

The time step simulation, where time is divided into intervals

Time step

t1 t2 t3 t4 …

event 3event 2event 1

t1 t2 t3

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Real vs. Simulated

Target system

Simulated system environment

HW

Rose-RT SW

model

Matlab/Simulink physical model

MCT

SW

Discrete Discrete and/or

continuous

Hybrid

Simulate the real-time behavior of the embedded system

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Case Study

Motor Control Loop Model

Set-point generator

Controller Motor Encoder

+

Criteria for case-study selection:

1) Low level of model complexity

2) Multidisciplinary aspect: SW + HW components

3) Interaction btw. SW and HW components

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Mapping on Tools

Motor Control Loop Model

Matlab/ Simulink

Set-point generator

Controller Motor Encoder

+

Rose-RT

Centralized Software Control

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Mapping on Tools

Motor Control Loop Model

Matlab/ Simulink

Set-point generator

Controller Motor Encoder+

Rose-RT

Distributed Software Control

Decision 1: select Distributed Software Control

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Computing resources

1 PC or 2 PC’s?

Rose-RT and Matlab/Simulink

Rose-RT Matlab/Simulink

Decision 2: use a single PC for simulation

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Outline

• Introduction: COMM within Bode-RC• Rose-RT• Simulink• Rose-RT and Matlab/Simulink: how to

couple?• State-of-affairs in COMM

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What is Rose-RT?

Software development environment for: • Creating UML models using the elements and diagrams

defined in the UML • Generating complete code implementations for those models • Executing, testing and debugging models

Uses the extensibility features of the UML for real-time

reactive system development

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Rose-RT from inside

• Stereotypes (special form) of class – Capsules • Template of active objects – Protocols • Template of ports

Environment

Capsule

portS1

S2

Ports: created and destroyed along with their capsule

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Active objects

Encapsulationshell

Ports

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Capsule: Behavior• Optional hierarchical state machine (signal handler with

run-to-completion semantics)

S1

S2 S3

S1

S2

S1

transitionS1toS2: {int x; x = 0; p2.send(s1); p3.send(s2); … };

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Traffic Lights example

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Timing in Rose-RTGoal: Understand the notion of time in multidisciplinary modeling

initialize

InitialInitial

worktimeouttimeout timeout2timeout2

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Timing in Rose-RT

• Time in Rose-RT is strongly connected with the system clock

• Precision is dependent on the granularity of the OS

• Accuracy is not guaranteed

• Timing in Rose-RT is unpredictable

• Simulation in Rose-RT can be achieved only by step-by-step execution

Goal: Understand the notion of time in multidisciplinary modeling

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Outline

• Introduction: COMM within Bode-RC• Rose-RT• Simulink• Rose-RT and Matlab/Simulink: how to

couple?• State-of-affairs in COMM

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What is Simulink?

Simulink is a software package for modeling and simulating dynamic systems

process of computing a system’s states and outputs over a span of time, using

information provided by the system’s model

x(states)

u (input)

y (output)

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Components of a Simulink model

Continuous blocks respond continuously to changing input. Discrete blocks respond to changes in input only at

integer multiples of a fixed interval called the block’s

sample time.

y2 (output)x1

(states)u1 (input)

y1 (output) x2

(states)u2 (input)

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Structure of a Simulink model

• A typical Simulink model includes sources, systems and sinks.

Simulink provides:•graphical block diagram capability•drag-and-drop blocks facility

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Simulink Environment

The Library Browser displays a tree-structured view of the Simulink block libraries installed on your system.

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Motor model

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Components of a Simulink model

• Solvers

You can specify the solver to use in the model or when running a simulation.

A program, called ordinary differential equation (ODE) solver, updates block inputs and computes block outputs and states at intervals from the simulation start time to the simulation end time.

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Timing in Matlab/Simulink• The simulation time in Matlab/Simulink and real clock are not

the same

The amount of time it takes to run a simulation depends on

- model complexity, computer’s speed, solver’s type, etc.

• Simulation time and real time are not proportional

Simulation time can run faster time acceleration

slower time stretching

• Facilities for scheduling and dealing with concurrency are not offered

is not suitable for simulation of SW

Goal: Understand the notion of time in multidisciplinary modeling

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TrueTimeReal-time kernels and network transmissions can be

simulated• Different processing times, priorities, and arbitrary scheduling

policies in the computer nodes can be specified• Various network protocols may be evaluated• By introducing disturbing traffic on the network, the effects of

unpredictability in the network communication can be studied

Limitations• Code generated by other applications cannot be directly used in TrueTime framework

Goal: Understand the notion of time in multidisciplinary modeling

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Outline

• Introduction: COMM within Bode-RC• Rose-RT• Simulink• Rose-RT and Matlab/Simulink: how to

couple?• State-of-affairs in COMM

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Rose-RT and Matlab/Simulink: How to couple?

Goal: Explore ways of coupling of tools used in MD modeling

Approach 1 Approach 2

MCT

MATLAB/SIMULINK

ROSE-RTMATLAB/SIMULINK

ROSE-RT

Decision 3: select loosely-coupled architecture

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Rose-RT and Matlab/Simulink:Where to place timing?

Goal: Explore ways of coupling of tools used in MD modeling

• Not feasible due to the timing service of Rose-RT

Provide timing

MATLAB/SIMULINK

Timing request

Provide timing

Timing request

Data Data

ROSE-RT

MCT

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Rose-RT and Matlab/Simulink: Where to place timing?

Goal: Explore ways of coupling of tools used in MD modeling

Provide timing

MATLAB/SIMULINK

Timing request

ROSE-RT

Provide timing

Timing request

Data DataMCT

• Timing is enforced to both modeling toolsets• No advantage of Matlab/Simulink timing is taken

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Rose-RT and Matlab/Simulink: Where to place timing?

Goal: Explore ways of coupling of tools used in MD modeling

• Rose-RT timing is not used

• Matlab/Simulink provides a well-defined notion of simulation time

MCT

Provide timing

MATLAB/SIMULINK

Timing request

ROSE-RT

Provide timing

Timing request

Data Data

Decision 4: use Matlab/Simulink as a timing provider

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Outline

• Introduction: COMM within Bode-RC• Rose-RT• Simulink• Rose-RT and Matlab/Simulink: how to

couple?• State-of-affairs in COMM

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ToDo• Rose-RT automated step-by-step execution

changes in RTController needed (complex!)

• Rose-RT timing compatibility with Simulink replacement of Windows NT Timing Services

• Simulation in intended target environment

durations of execution of Rose-RT functions on a target OS should be available

State1 State2

InitialInitial

operation_durationoperation_duration

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Questions