Rhapsody and mechatronics, multi-domain simulation

Accelerating Product and Service Innovation

© 2013 IBM Corporation1

Graham Bleakley Ph.D.Solution Architect A&D and AutomotiveIBM Software, Rational

Mechatronics and its application with Rhapsody Design Manager

© 2013 IBM Corporation


Agenda What is mechatronics and How does it fit with Continuous

Engineering ?

The practicalities of Mechatronic Modelling with Rhapsody Mathematical modelling tools for SE and Mechatronics

Use of Simulink and Parametrics Constraint EvaluatorSpecification models

Design Models

Use cases

Modelica Introduction

Functional Mockup Interface and Unit:-How it works

Use cases

Vision of RDM as FMI simulation backbone

References


Accelerating Product and Service InnovationAccelerating Product and Service Innovation

The ‘make up’ of products and systems has changed

Mo

re

Time

Consumer expectations

Complexity

Softwareand electronics



What is Mechatronics ? Interdisciplinary approach to engineering that involves the

integration of Mechanical

Electrical

Software

Requires a system engineering approach to develop properly integrated systems

Also know as:- Cyber-Physical Systems (CPS)



Mechatronics and Modelling Emphasis on understanding the physical behaviour of the

systems as well as the logical behaviour Requires mathematical modelling tools

Mathematical modelling tools need to be integrated into the logical behaviour models Physical representations of the systems can and do affect the

performance of the system under design

Why do you model the physical systems ? Verify that you can meet functional and non-functional requirements

Trade studies (parametric analysis)

Ensure that the system does what it says It can do

Continuous Engineering Simulation

Connected Information



6

Quality managementAnalysis, design and prototyping Requirements management

Workflow, Planning, Task & Change Management

Mechatronics Modelling and Continuous Engineering (Simulation)

Engineering context

MarketAnalytics

System Verificationand Validation

SystemTest

SystemRequirements

SystemDesign

Deployment/Release to Mfg.

CustomerRequirements

Operations and Maintenance

Implementation

Decom

position

and Definition

Inte

grat

ion

and

Valid

atio

n

Agile SoftwareEngineering

Electrical/Electronics

Design

MechanicalDesign

Iterative

MechatronicsModelling



7

MBSE and Open Information



8

IBM helps you turn product development into a competitive advantage

Improve systems engineering to tackle growing product complexity

Improve software development to deliver innovation faster

With an open, integrated systems approach that enables access to all engineering and related information

Engineering context

Open standards

MarketAnalytics

System Verificationand Validation

SystemTest

SystemRequirements

SystemDesign

Deployment/Release to Mfg.

CustomerRequirements

Operations and Maintenance

Implementation

Decom

position

and Definition

Inte

grat

ion

and

Valid

atio

n

Agile SoftwareEngineering

Business Engineering Operational

Enterprise information

Electrical/Electronics

Design

MechanicalDesign

Iterative



The practicalities of Mechatronic Modelling with Rhapsody



10 HVC 2012Nov. 2012

Developing Mechatronic/CPS (usually) means doing Systems Engineering

Commonly used in complex multi-disciplinary systems: Requires disciplined requirements analysis (functional and non-

functional analysis, trade-offs, etc.)

Requires coordination between domain specific engineering teams (managing engineering artifacts)

High risk of failure, esp. during integration, Leads to non-trivial emergent behavior -> simulations!

Source: Sheard, Sara, A.,Systems Engineering Roles Revisited, Proceedings of the 10th Annual International Council of Systems Engineering, 2000



11 HVC 2012Nov. 2012

Typical Mechatronic or CPS modelling

Source: Edward A. Lee and Sanjit A. Seshia, Introduction to Embedded Systems, A Cyber-Physical Systems Approach, http://LeeSeshia.org, ISBN 978-0-557-70857-4, 2011



12

There is no single tool that fits all needs• Rhapsody is excellent for embedded systems design (statecharts,

activity diagrams, sequence diagrams)

• Modelica tools are intended for physical modeling

• Simulink strength is control design

Systems Engineers generally choose a single tool that best meets their needs, making compromises in multi-domain modeling• Often organizations dictate the tool

Change in tool choice means loss of legacy models

Tool choice often prohibits inter-organizational cooperation

Rhapsody provides a way to work with a variety of mathematical modelling tools

Challenges



Mechatronic Modelling tools and Rhapsody

Text based tools (work with PCE, one shot analysis) MatLab

Maxima

Block diagram based tools (DM and continuous time based analysis) Simulink

Lab View

Time based analysis on another tool Modelica (OO textual mathematical modelling) Implemented

graphicaly in tools likeDymola

SimulationX

Integration is via the Functional Mockup Interface (FMI)



Use different tools for different types of analysis (PCE) Useful for calculating properties of

systems using Parametric diagramsTotal system mass

Total systems weight

Examine Non-functional requirements i.e. totalMass<17 Kg

Maxima is easier to use than MatlabEverything driven by function calls that

have to be defined in Matlab



Use different tools for different types of analysis (Integrated) Simulink and National Instruments

The mathematical model is embedded in the plant model

Connected via flow ports

Different levels of analysis

Specification level

Understanding systems level non-functional requirements i.e. max motor torque



Satisfying Systems Level Requirements

By Linking requirements to model Simulink models at the block or even the model level we can show traceability

This can be brought out in DM and RELM see https://w3-connections.ibm.com/files/app#/file/975b9225-9a41-4834-

af69-99450113100d



Simulink and PCE for Design

Possible to feed analysis from PCE model into a Design Model Simulink model is more detailed and shows components with real

component values



Leads to detailed analysis

Specification model leads to ball park design figures

Design model leads to identification of potential components Compare specification analysis to design analysis models

Evaluate non-functional requirements at different levels of abstraction

Max torque (spec) Max torque (design) Max motor torque due No gearbox actual masses/gb to gearbox



Possible workflow for PCE and Simulink

Specification Level (use case/ functional and non-functional analysis) Take initial requirements and derive simulink or analytical model

using parametric diagrams (and Maxima) to understand things likeExpected torques for drive systems based on non-functional requirements

• Expected mass of components

• Timing requirements to complete an overarching operation of the system

Basic control strategies

• Differentiate between acceleration, velocity controls

Gives you the ability to do some initial understanding and refinement of the systems design

Derive further requirements

Start to think about different implementation strategies



Possible workflow for PCE and Simulink Design Synthesis level (Physical Architecture)

Use Parametric diagrams to understand how non-functional requirements are met

Total Mass of the System

Total Cost of the System

Start to do optimisation of the system using real component values

Value over Excel is that:-

Component values and the design decisions are captured directly in the model

Through RDM and RELM there is potential to link into design catalogues of specific components

Capture the physical architecture as a Rhapsody model with the physical behaviour captured in a detailed plant model created in Simulink

Plant model uses real component data to verify that higher level functional and non-functional requirements are met

In the same ball park as the specification model (verification of the initial assumptions)

Provides a test case for the implementation



HVC 2012

Usage on the “V-Model”

Requirements Analysis

Functional Decomposition

Design Synthesis

Analysis

Design

Implementation

System

s Eng.

Softw

are Eng.

Simulation in RhapsodyGenerate code

(algorithmic integration)

Component/Subsystem Spec.Simulation in Simulink

* Doing trade studies with PCE is not shown in this tutorial

PCE, Maxima/MatlabSimulation in Simulink

Analysis Non-Functional System Requirements

Trade Study

Parametric Constraint Evaluation (PCE)*



Usage model for DM and Simulink Be careful

Simulink has basic configuration control built into it

Has a library mechanism to manage models

Sophisticated users develop model libraries and reuse components

In DM you can manage Simulink models as part of a configuration and the owning Rhapsody model This would work best under actively managed mode

If doing Hybrid simulation it is currently best to work in actively managed mode

You can do simulation on DM but you need to reference the original Simulink model or files, not the version published to DM

You might get Simulink users generating code and embedding in Rhapsody This is more sw orientated and would suggest using externally

managed mode



HVC 2012

Modelica

A standardized textual language for modeling physical systems

Annotations are also standardized now and can be used to render diagrams

Developed since 1996 by the Modelica Association https://www.modelica.org

Current version 3.3 (May 2012)

Modelica is Object-Oriented (see right side)

Has a large (~30) set of free and commercial libraries for different domains (source: https://www.modelica.org/ModelicaLibrariesOverview)

Implemented by various free and commercial tools: (Dymola, Open Modelica, Math Modelica)

The OMG SysML4Modelica profile extends SysML to model Modelica constructs in SysML (IBD) and roundtrip Modelica models back to SysML

Source: https://modelica.org/publications/papers/Eurosim98Modelica.pdfSource: https://modelica.org/publications/papers/Eurosim98Modelica.pdf

https://www.modelica.org/

https://www.modelica.org/ModelicaLibrariesOverview


Accelerating Product and Service InnovationFMI – Functional Mockup Interface - Background

• FMI development initiated, organized and headed by Daimler AG

• Improved Software/Model/Hardware-in-the-Loop Simulation, of physical models from different vendors.

• Open Standard

• 14 Automotive Use-Cases to evaluate FMI.

Enginewith ECU

Gearboxwith ECU

Thermalsystems

Automatedcargo door

Chassis components,roadway, ECU (e.g. ESP)

etc.

functional mockup interface for model exchange and tool coupling

Blocwitz, Otter, et al, retrieved from: https://trac.fmi-standard.org/export/700/branches/public/docs/Modelica2011/The_Functional_Mockup_Interface.ppt

The FMI development is part of the ITEA2 MODELISAR project


Accelerating Product and Service InnovationFunctional Mock-up Interface (FMI) Approach

Problems / NeedsComponent development by supplier

Integration by OEM

Many different simulation tools ?

supplier1 supplier2 supplier3 supplier4 supplier5

OEM

supplier1

tool 1

supplier2 supplier3 supplier4 supplier5

tool 2 tool 3 tool 4 tool 5

FMI OEM

SolutionReuse of supplier models by OEM:

DLL (model import) and/or

Tool coupling (co-simulation)

Protection of model IP of supplier

!supplier1

supplier2

supplier3

OEM

Added ValueEarly validation of design

Increased processefficiency and quality

Blocwitz, Otter, et al, retrieved from: https://trac.fmi-standard.org/export/700/branches/public/docs/Modelica2011/The_Functional_Mockup_Interface.ppt



Multi-domain engineering use case

1. Systems Eng. creates SysML model of overall system

2. Software Eng. creates UML models of software components of vehicle and control station

3. Mechanical Eng. creates Modelica models for mechanical components and control

4. FMUs created for behavioral models

5. Simulation Engineer cofigures Simulation using FMUs

6. Simulation Engineer performs Simulation verifying System behavior

7. Simulation Engineer delivers results



Fully integrated use cases

1. Systems Engineer specifies a system architecture in Rhapsody

2. Systems Engineer exports some of the components to physical modeling tool (e.g. SimulationX) and control modeling tools (e.g. Simulink)

3. Mechnical Engineers models mechnical components within the physical modeling tool

4. Software Engineer models software components in Rhapsody

5. Control Engineer models the control elements

6. Any one of the engineers can deploy the integrated model into the simulation tool and run the simulation



Hybrid Simulation Platform Vision

Hybrid Simulation Platform

Modelica Plant Model

Simulink model computation algorithm

UML based behavioral model

System design

Comp11 comp21

com p31

System composition

Simulation center

Contracts/ Simulation Monitors

System Requirements

Models, designs and results repositoryVersion control and dependency analysis

FMU1 FMU1

FMU1

Textual requirements

Models

28

SW Domain

Physical Domain

HiL components



References

CEE-1093, Case Study: Simulation of Complex Hybrid Systems by Using FMI for Israel Aerospace Industries Eldad Palachi, Daniel Wadler (Innovate 2014)

Simulating Cyber-Physical Systems using SysML and Numerical Simulation Tools, Eldad Palachi 8th Haifa Verification Conference, Nov. 2012

http://www.research.ibm.com/haifa/conferences/hvc2012/papers/HVC2012Eldad_Palachi.pdf

Introduction to Parametric Modelling

https://www.youtube.com/watch?v=jpxXjkIsnmE

For those internal to IBM (although I may make this externally available)

Andy Lappings demo of Rhapsody, Simulink and DM based on ACC model

https://w3-connections.ibm.com/files/app#/file/975b9225-9a41-4834-af69-99450113100d

Mechatronics Group on Lotus Connections

https://w3-connections.ibm.com/wikis/home?lang=en#!/wiki/Mechatronics%20modelling%20Rhapsody%2C%20Simulink%20and%20PCE/page/Welcome%20to%20the%20Systems%20Engineering%20Mechatronics%20modelling%20with%20Rhapsody%2C%20Simulink%20and%20PCE%20page

Or to make it easier

http://ibm.co/1A8awWZ



Integration points with MATLAB tools (July 2014) - summaryName Tools Main Audience Description Canonical Workflow

“hosted simulation” Rhapsody, Simulink, Embedded Coder

Software Engineers Import Simulink models and generated code from embedded coder to Rhapsody and generate C/C++ code for execution (with or without animation)

- Build Simulink Model- Generate code for the Simulink model- Import to Rhapsody- Specify usage and composition- Generate and execute in Rhapsody

“design control systems”/”plant modeling”

Rhapsody, Simulink

Systems Engineers Export structured blocks parts typed by “Simulink blocks” to Simulink and run the simulation in Simulink

Note: Relies on S-Function generation from Rhapsody

- Export a “stub” block from Rhapsody to Simulink: creating a skeleton model

- Specify the behavior of the block as a Simulink model

- Import the Simulink model back to Rhapsody (if the interface changed)

- Specify an IBD of a structured Simulink block with parts typed by SysML blocks connected to parts typed by Simulink blocks

- (Optionally) specify simulation properties (start/end times, plots…) in Rhapsody

- Export the composition to Simulink and run the simulation

“parametric constraint evaluator” (PCE)

Rhapsody, MATLAB + Math Symbolic Toolbox OR MAXIMA

Systems Engineers Solve and perform analytical simulation of a set of SysML parametric diagrams

- Specify a set of equations and bind the variables to block attributes using parametric diagrams

- Define constraint views to group sets of parametric diagrams and associate with instance specifications

- Solve the constraint sets or plot time dependent behavior

- Iterate over the values and update the model with the results

“Simulink DM integration”

Design Manager (DM) and Simulink

Systems and Software Engineering

Externally or actively manage Simulink models in Rhapsody design manager

- Publish a Simulink model on DM OR- Actively manage Simulink models in DM

(save , load ,.lock, etc.)



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