modelon modelica executable requirements ansys conference 2016

7 June, 2016

Dr. Hubertus TummescheitBoard Member, Modelica AssociationCEO, Modelon Inc.

Applying FMI/FMU & Modelica for Design and Co-simulation of Complex Dynamic Systems

The Functional Mockup Interface: FMI overview Modelica: a very brief overview A Real-World Example: Active Grill Shutter Controls Vehicle Thermal Management with Modelica Continuous Validation of System Requirements

• Intermediate results from ITEA3 MODRIO project Iterative Controller Development Using Modelica Conclusions

AGENDA

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FUNCTIONAL MOCKUP INTERFACEA brief overview

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FUNCTIONAL MOCKUP INTERFACE (FMI)• Tool independent standard to support both model exchange

and co-simulation of dynamic models

• Origin with EU-funded MODELISAR project led and initiated by Daimler

• FMI currently supported by more than 85 tools (see www.fmi-standard.org for most up to date list)

• Active development as Modelica® Association project • FMI 1.0 (2010), FMI 2.0 released July, 2014 with additional

functionality • Endorsed by many organizations: NAFEMS/INCOSE, ProStep,

42023-05-01

FMI IN A NUTSHELL• What is FMI?

an application programming interface and its semantics

an xml schema that describes the model structure and capabilities

the structure of a zip file that is used to package the model, its resources and documentation.

• 85 tools support FMI in 9 different categories.

05/01/2023 © Modelon 5

Supported by >85 tools:• 0/1-D ODE Simulators• Multibody Simulators• HIL Simulators /SIL tool chains• Scientific Computation tools• Data analysis tools• Co-simulation Backplanes• Software development tools• Systems engineering tools• SDKs

FMI = BUSINESS ADVANTAGE• Same model – different applications

2013-09-02 © Modelon

FMI: A BUSINESS MODEL INNOVATION1. FMI-compliant tools often allow liberally

licensed export of models for distribution in the organisation and to partners.

2. Exported FMUs most often don’t require a license from the model authoring tool.

3. Deployment from few simulation specialists to designers, domain specialists, control engineers One FMU used by many engineers (control

design) One FMU run on many cores

(robust design, V&V testing)72023-05-01

FMI: A BUSINESS MODEL INNOVATION1. Separate the model authoring tool from

the model execution tool!2. Free the model unit (FMU) from license

restrictions3. Make the standard widely accepted:

https://fmi-standard.org/tools 4. Increased Collaboration possibilities

among typically disparate functional areas

5. Reduced risk & reduction in liability through better virtual verification

2023-05-01 8

FMI STANDARD: RAPID EVOLUTION What’s under consideration for the next releases?

Make it easier to couple 3D FEA models with dynamic system models (e.g. SimScape, Modelica)

Support non-causal connectors • Use Craig-Bampton approach for reduced order models

Extensions for co-simulation model management Systems Simulation & Parameterization (SSP)

Simulate complex cyber-physical systems containing many FMUs

Integrate with other standards to provide tool-independent model traceability and archive of M&S results

• AutoSAR and SAE 26262 (Automotive Industry)• DO 178 (Aerospace and Defense Industry)• LOTAR/AP209 (A&D, Shipbuilding, Power)

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What is Modelica ?• Modelica is a special purpose programming language

for modeling cyber-physical systems. Modelica is: A vendor-neutral standard Multi-domain Object oriented Equation based (acausal) Covers multiple formalisms With a consistent graphical and textual system

representation

• Modelica is like LEGO for Physical Systems Modeling

Object-Oriented ModelingComponent

• Each Icon represents one physical component. For example, electrical resistance, mechanical device, pump

Connection

• A connection line represent the actual physical coupling. For example, electrical wire, rigid mechanical coupling.

Connector

• Variables in the connectors define the Interaction to other objects

• A component consists of connected sub-components (= hierarchical structure) and/or is described by equations.

Analysis

• Dymola® by Dassault Systèmes• IGNITE by Ricardo • LMS Imagine.Lab AMESim® by Siemens• MapleSim® by MapleSoft®

• MWorks by Suzhou Tongyuan• OPTIMICA® Studio by Modelon• SimulationX® by ESI/ITI GmbH• Simplorer by ANSYS• solidThinking-Activate by Altair• Wolfram SystemModeler by Wolfram

• JModelica.org by Modelon• OpenModelica by the Open Modelica Consortium

MODELICA SUPPORTING TOOLSCOMMERCIAL & OPEN SOURCE/ALPHABETICAL

• My company is actively involved with using and supports these systems modeling and simulation open standards:

a) FMI 1.0b) FMI 2.0c) Modelicad) All of the abovee) Not sure

AUDIENCE POLL QUESTION

REAL WORLD EXAMPLEFuel economy is won or lost on the system level

2023-05-01 © Modelon 14

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• Other options for execution & automation: Matlab/Simulink Excel Python Any FMI execution

platform

GRILL SHUTTER CONTROLLER DEVELOPMENT

Hardware Model: Dymola/Modelica

Controller/Software development platform: IBM Rational RhapsodyANSYS SCADE SuiteThe MathWorks® Simulink®etc.

Target: best-in-class fuel economyREAL WORLD EXAMPLE

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Grill shutters:• Reduce aerodynamic

drag• Improve fuel economy

Non-MBSE approach:REAL WORLD EXAMPLE

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Prototype vehicle starts overheating:• Grill shutters reduce aero drag

but degrade cooling• New control strategies

required• Subsystem optimization

resulted in addition of fans for cooling

• Higher cost and missed FE target

Develop prototype

Track test prototype

Sample Vehicle!

MBSE approach:REAL WORLD EXAMPLE

2023-05-01

1. Define requirements

2. Develop model3. Develop test

cases4. Define

requirement monitors

Test virtual system instead of physical prototype!

Find requirement violation – catch overheating issue early

Improve system design to also account for thermal needs

VEHICLE THERMAL MANAGEMENT MODELOverview

Integrated model for fuel economy and vehicle thermal management• Vehicle model with loads and losses• Vehicle heat loads (engine, friction,

transmission)• Lumped engine thermal model• Coolant and oil circuits with possible additions

of other thermal fluid circuits • Drive cycles (speed, grade, wind, etc.)• Airflow effects• Key vehicle and thermal controls (fan, grill,

INTEGRATED VEHICLE THERMAL MANAGEMENT (VTM) MODEL

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Multi-domain physical model libraries in Modelica Libraries developed by Modelon domain experts leveraging

industrial experience and consulting projects

STANDARD MODEL LIBRARIES

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Thermal Mechanic

al Electrical Coolant Air

VTM SYSTEM MODEL

2023-05-01 © Modelon

THERMAL SYSTEM MODELING

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Air Flow

Coolant Circuit

Heat from vehicle systems enters

coolant fluid

Coolant

DRIVER AND DRIVE CYCLES

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Boundary conditions define test case conditions:• Road grade and surface• Ambient air (temperature,

pressure, wind speed, etc.)• Desired vehicle speed profile

(drive cycle)

Ambient

Drive Cycle

TYPICAL DRIVE CYCLE RESULTS25

0 250 500 -5

Time [s]

0 250 500 -40

Time [s]

0 250 500

Time [s]

0 250 500 -0.2

Time [s]

TYPICAL DRIVE CYCLE RESULTS (THERMAL)

Fan speed is lowWhen vehicle is fast

Thermostat opensAs engine warms up

Temperature can only be exceeded for at most X seconds

REQUIREMENTS VERIFICATIONContinuous feedback on compliance of requirements

MBSE approach:

REQUIREMENTS VERIFICATION

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Stakeholder Requirements

Design Requirements

RequirementsManager

MBSE approach:

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Design Requirements

RequirementsManager

Virtual SystemReal System

MBSE approach:

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Design Requirements

RequirementsManager

FormalizedRequiremen

MBSE approach:

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Design Requirements

RequirementsManager

tsTranslate to Executable

Test Cases Requirements Monitors

Verifier Models

Batch ExecutionExecutable

Environment

MBSE approach:

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Design Requirements

RequirementsManager

Verifier Models

EnvironmentAll Pass?

Result Report

Modify:• Reqs• System• Model

NoCompleteCoverage?

MBSE approach:

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Design Requirements

RequirementsManager

Verifier Models

Result Report

NoCompleteCoverage?

These are usually high level, not always easily testable.

MBSE approach:

2023-05-01

Design Requirements

RequirementsManager

tsTranslate

to Executabl

Verifier Models

Result Report

NoCompleteCoverage?

These are low level and testable. When possible also specified in an open standard language.

MBSE approach:

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Design Requirements

RequirementsManager

Verifier Models

Result Report

NoCompleteCoverage?

These exercise the system dynamics.

MBSE approach:

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Design Requirements

RequirementsManager

Verifier Models

Result Report

NoCompleteCoverage?

These are the executable checks to verify the requirements are met.

MBSE approach:

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Design Requirements

RequirementsManager

Verifier Models

Result Report

NoCompleteCoverage?

Specifying the requirements in a standard way opens the possibility to automatically generate the executable monitors.

MBSE approach:

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Design Requirements

RequirementsManager

Verifier Models

Result Report

NoCompleteCoverage?

Combining a test case with one or more monitors allows requirements to be verified.

MBSE approach:

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Design Requirements

RequirementsManager

Verifier Models

Result Report

NoCompleteCoverage?

The complete set of executable verifier models can be tested automatically.

MBSE approach:

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Design Requirements

RequirementsManager

Verifier Models

Result Report

NoCompleteCoverage?

The report shows a summary overview of the pass/fail results.

MBSE approach:

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Design Requirements

RequirementsManager

Verifier Models

Result Report

NoCompleteCoverage?

When requirements are not met, modifications can be made to the system, model or even the requirements.

MBSE approach:

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Design Requirements

RequirementsManager

Verifier Models

Result Report

NoCompleteCoverage?

The requirements manager should be able to verify that all requirements will be tested by the set of verifier models.

MBSE approach:

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Design Requirements

RequirementsManager

Verifier Models

Result Report

NoCompleteCoverage?

Translate to Executable

MBSE approach:

AUTOMATED REQUIREMENTS VERIFICATION

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Design Requirements

All Pass?

Verifier Models

Batch Execution

Result Report

Executable EnvironmentYes

RequirementsManager

NoCompleteCoverage?

Degree of Automation?

REQUIREMENTS MANAGEMENT47

Design Requirements

RequirementsManager

Requirements management tools IBM DOORS/DOORS NG

Requirements quality tools Requirements Quality Suite from The Reuse Company

Requirements traceability IBM Requisite Pro, integration with ClearQuest for testing, .. Reqtify (Dassault Systèmes), links Modelica code to req. in DOORS

Requirements formalization? Testing of requirements against system model? Continuous Integration tools to repeat tests for every change to the system?

Translate to

Executables

MBSE approach:

EXECUTABLE REQUIREMENTS

2023-05-01

Design Requirements

All Pass?

Verifier Models

Batch Execution

Result Report

Executable EnvironmentYes

RequirementsManager

NoCompleteCoverage?

Focus on this part

2023-05-01 49

AUTOMATED REQUIREMENTS VERIFICATION• Systems Engineering centric FMI-based workflow example:

automated requirements verification for hardware and software requirements

RequirementsFormalized

requirements

Executable model of requirements (e.g.

Physical plant Model of plant

Deployable model of plant

Software specSoftware model or prototype

Deployable model of

software (FMU)Deployable model of

environment

Automate Analysis & Deploy to team!

Development of a customized workflow to allow rapid iterations of plant & software configuration

ITEA3 Project:• Model Driven Physical Systems Operation

WP: Define requirements formally and check them automaticallywhenever a Modelica system model is simulated

CURRENT RESEARCH, ITEA3 (EU)

2023-05-01 © Modelon

Example„Pumps should not cavitate when they are operating“ (p(t) ≥ pcav if operating)→ Define formally + associate conveniently to all pumps + check automatically + report issues automatically

Otter et al: Formal Requirements Modeling for Simulation-Based Verification, Modelica’2015

State of the art• Not practical (impossible) with available Model Checkers since requirements

depend on the numerical solution of Differential-Algebraic Equations (DAE).• Limited tool support for connecting „textual requirements“ with simulation models

(e.g. Simulink with Validation & Verification toolbox + IBM DOORS; 3DExperience with Reqtify + Dymola, ...).

• Research languages + tools (e.g. ModelicaML from Airbus Innov./LiU).

MODRIO VIEW- REQUIREMENTS VERIFICATION

Natural language: „Pumps should not cavitate when they are operating“

FORM_L (formal language developed by N. Thuy, EDF) required property R2 = { P in Pumps | during P.InOperation check not P.Cavitate };

1. Define requirements formally

2. Design Architecture (e.g. with SysML)

3. Provide Behavioral Models to evaluate design (Modelica)

4. Associate requirements and architecture with behavioral models

5. Verify Behavior

Otter et al: Formal Requirements Modeling for Simulation-Based Verification, Modelica’2015

Modelica extension to express requirements (under development) FORM-L-inspired Modelica library, based on 3-valued logic:

Satisfied, Undecided, Violated Large Library of pre-defined requirement structures Executable and formal model of requirements, in Modelica

language

PROTOTYPE IMPLEMENTATION

2023-05-01 © Modelon

(x,y) coordinates of input must stay within closed polygon(output: closest distance to polygon + property)

THERMAL MANAGEMENT REQUIREMENTSMonitors for requirements compliance checking

05/01/2023

REQUIREMENTS DOCUMENT

05/01/2023

TEST CASES

Test cases exercise system (or parts of system) under various operating conditions

Adding test cases can improve coverage

05/01/2023

REQUIREMENTS MONITORS

Monitors used to check pass/fail status of requirements from test cases

05/01/2023

REQUIREMENTS MONITORS• Monitors from the new Modelica

Requirements library (Otter et al., 2015)

• Checks the conditions of the requirement

• Reports pass, fail, or undecided• Constructed from standard blocks

from the Requirements library• Monitors can be collected in one

submodel, and be compiled into an FMU as well

M. Otter, N. Thuy, D. Bouskela, L. Buffoni, H. Elmqvist, P. Fritzson, A. Garro, A. Jardin, H. Olsson, M. Payelleville,W. Schamai, E. Thomas, AND A. Tundis. Formal Requirements Modeling for Simulation-Based Verification. Proceedings of the 11th International Modelica Conference, Paris, France, September 21-23., pp. 625-635 2015. http://www.ep.liu.se/ecp/118/067/ecp15118625.pdf

05/01/2023

REQUIREMENTS MONITORSMonitors added to test cases – in this case a unit test of the simple controller

Requirements violated (0 of 2): None

Requirements untested (0 of 2): None

Requirements satisfied (2 of 2): (checkReq3.requirement): Grill shutter opened below 15 m/s (checkReq4.requirement): Grill shutter closed above 18 m/s

0 4 8 12 16 20

0 4 8 12 16 20 -0.2

Time [s]

Overall pass or fail log direct from library

Vehicle VelocityGrill Command

THERMAL MANAGEMENT REQUIREMENTSTesting Automation with Optimica Testing Toolkit (OTT)

05/01/2023

OPTIMICA TESTING TOOLKIT Key features

• Modelica and FMI cross testing platform• Flexible test authoring• Automated test execution and reporting

Architecture• Core

Command line tool for running testsUses OPTIMICA compiler toolkit for test retrieval

• GUITool for creating, updating and running testsReviewing and updating results

05/01/2023

OPTIMICA TESTING TOOLKIT GUI

• Test suite defines a collection of test cases for batch execution

• Automated execution of complete suite of tests

05/01/2023

OPTIMICA TESTING TOOLKIT GUI

Report shows summary of results with hyperlinks to detailed reports

05/01/2023

CONTINUOUS INTEGRATION• CI integration for

automated requirement verification

• Hudson, Jenkins, TeamCity• The test specification can

be in the Modelica code and converted

• The test specification can be created in the GUI and version controlled

• Multiple reports from same data:• Human readable HTML

report • Machine readable Junit

xml report

05/01/2023

CONTINUOUS INTEGRATION1. User commits change to

controller2. Automated testing verifies all

requirements are met

Rapid feedback to developer when things get broken!

GRILL SHUTTER CONTROLLERDevelopment Cycle

SIMPLE GRILL SHUTTER CONTROLLER

Initial bang-bang controller with hysteresis

0 250 500

Time [s]

Vehicle Speed Closing Threshold Opening Threshold

Close the shutters when the vehicle speed exceeds the closing thresholdClose Close

Open Open

Open the shutters when the vehicle speed is below the opening threshold

Implemented as a state machine from Modelica StateGraph2 library

Activation of states completely opens or closes grill shutters

State machine transitionsInitial state is grillOpen

Transition condition to closed state based on vehicle speed thresholds

CONTROLLER PERFORMANCESimple Grill Shutter Controller

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CONTROLLER PERFORMANCEBaseline system without grill shutters

0 250 500 -5

Null controller holds grill shutters in wide open position

Vehicle runs the US06 drive cycle

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CONTROLLER PERFORMANCEBaseline system without grill shutters

0 250 500

0 250 500 -500

0 250 500

0 250 500 -5

Fuel Economy [mpg]

Engine Speed [RPM]

Coolant Temp [°C]

Fan Speed [RPM]Vehicle Speed [m/s]

-------- 100.0 % of US06_no_shutters requirements are satisfied -------------Requirements violated (0 of 3):None

Requirements untested (0 of 3):None

Requirements satisfied (3 of 3):(checkReq1_1.requirement): Coolant temperature must not exceed 368.15K for longer than 20 seconds(checkReq2_1.requirement): Coolant temperature shall not exceed 371.15K(checkReq3_1.requirement): Grill shutter opened below 15 m/s

Connect to system model

Controller commands grill shutter position, modifies air flow to stack and aero drag

Replace grill null position controller with state based control logic

Execute test cases

0 250 500 -5

Repeat the US06 drive cycle

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CONTROLLER PERFORMANCEReview results from continuous integration

05/01/2023

0 250 500

Baseline Simple Controller

0 250 500 75

0 250 500 -500

0 250 500

0 250 500 -5

CONTROLLER PERFORMANCESystem with simple grill shutters

Fuel Economy [mpg]

Engine Speed [RPM]

Coolant Temp [°C]

Fan Speed [RPM]

Vehicle Speed [m/s]

-------- 50.0 % of US06_FMU_simpleGC requirements are satisfied -------------Requirements violated (2 of 4):(checkReq1_1.requirement at 86.3981 s): Coolant temperature must not exceed 368.15K for longer than 20 seconds(checkReq2_1.requirement at 111.523 s): Coolant temperature shall not exceed 371.15K

Requirements satisfied (2 of 4):(checkReq3_1.requirement): Grill shutter opened below 15 m/s(checkReq4_1.requirement): Grill shutter closed above 18 m/s

Failed thermal requirements

400 440 480 520 560 600 15.5

In addition to failed thermal requirements, fuel economy actually decreased!

Fuel Economy [mpg]

75 100 125 94

Temperature exceeds 95°C for more than 20 seconds

Temperature exceeds 98°C

05/01/2023

0 250 500

0 250 500 75

0 250 500 -500

0 250 500

0 250 500 -5

CONTROLLER PERFORMANCESystem with simple grill shutters

Fuel Economy [mpg]

Engine Speed [RPM]

Coolant Temp [°C]

Fan Speed [RPM]

Vehicle Speed [m/s]

0 250 500 -500

Closed grill shutters reduces air flow through the stack. Compensated for by increased the fan speed, draws more electrical power from the alternator… and ultimately the engine.

Fan Speed

IMPROVED CONTROLLER DESIGN

05/01/2023

IMPROVED CONTROLLER DESIGN Improved controller

Additional inputs to account for system temperatures

05/01/2023

Additional state for new logic

05/01/2023

PID modulates grill position based on weighted average temperature

CONTROLLER PERFORMANCEImproved Grill Shutter Controller

05/01/2023

CONTROLLER PERFORMANCEReplace the simple bang-bang control logic with the improved controller

0 250 500 -5

Repeat the US06 drive cycle

05/01/2023

CONTROLLER PERFORMANCEReview results from continuous integration

Requirements now pass across multiple test cases

05/01/2023

0 250 500

Baseline Simple Controller Improved Controller

0 250 500

0 250 500 75

0 250 500 -500

0 250 500 -5

CONTROLLER PERFORMANCESystem with improved grill controller

Fuel Economy [mpg]

Engine Speed [RPM]

Coolant Temp [°C]

Fan Speed [RPM]

Vehicle Speed [m/s]

-------- 100.0 % of US06_FMU_advancedGC requirements are satisfied -------------Requirements violated (0 of 3):None

Requirements satisfied (3 of 3):(checkReq1_1.requirement): Coolant temperature must not exceed 368.15K for longer than 20 seconds(checkReq2_1.requirement): Coolant temperature shall not exceed 371.15K(checkReq3_1.requirement): Grill shutter opened below 15 m/s

Requirements now pass

400 440 480 520 560 600 15.5

Fuel economy improved, also over baseline

Fuel Economy [mpg]

• Further integration with MBSE/Reqs tools for fully automated traceability

• Complete automation of requirements verifcation process

• … much more progress on tools is needed to have a coherent work flow from stakeholder requirements to formal requirements and finally fully automated requirements

FUTURE FMI/FMU GOALS

• FMI simplifies tool connectivity and allows more efficient work flows & processes

• FMI enables true MBSE, with executable models

• Requirements monitors make the requirements executable and enables the ability to check requirements compliance continuously during systems development

• Process automation is key to integrate the requirements verification with MBD.

SUMMARY & CONCLUSIONS

FMI=CONNECTED MBSE

modelon modelica executable requirements ansys conference 2016

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