The guidelines manual describes the steps for coupling Modelica modelling language based simulation environment OpenModelica and genric optimisation program GenOpt

Dudhee, Vishak

Vukovic, Vladimir

English

NEUROSURGERY ENTHUSIASTIC WOMEN SOCIETY

Coupling OpenModelica and GenOpt: Guidelines

Teeside University's Research Repository

          Coupling OpenModelica and GenOpt Guidelines Version 2.1   16th August 2021         Vishak Dudhee and Dr Vladimir Vukovic v.dudhee@tees.ac.uk | v.vukovic@tees.ac.uk  School of Computing, Engineering & Digital Technologies Teesside University, United Kingdom CONTENTS 1 OpenModelica .................................................................................................................. 3 1.1 Creating a Model ...................................................................................................... 3 1.2 Editing the Model ...................................................................................................... 4 1.2.1 Load File Command .......................................................................................... 4 1.2.2 Print Result File ................................................................................................. 5 1.3 Create a Script .......................................................................................................... 5 1.3.1 Script Creation Process ..................................................................................... 5 1.3.2 Run Script (Optional) ......................................................................................... 6 2 GenOpt ............................................................................................................................ 6 2.1 Coupling Files ........................................................................................................... 6 2.2 Initialisation File ........................................................................................................ 7 2.3 Configuration File ..................................................................................................... 7 3 Example – hsysmodel ...................................................................................................... 8 3.1 Script - Command Prompter ..................................................................................... 8 3.2 OpenModelica Simulation ......................................................................................... 9 3.3 GenOpt Optimisation ................................................................................................ 9     Coupling OpenModelica and GenOpt  2  The software version used in the coupling process, the Modelica library version and the operating system specifications are: Software: • OpenModelica v1.17.0 (64-bit)   Connected to OMSimulator v2.0.0.post284-gc8ec782-mingw • GenOpt 3.1.1 Modelica Library: • Modelica Standard Library V4.0.0 (Version Date: 2020-06-04) Operating System: • Windows 10 Home  Version: 20H2  System type: 64-bit operating system, x64-based processor  OS build: 19042.867                     Coupling OpenModelica and GenOpt  3   1 OPENMODELICA 1.1 CREATING A MODEL  A model of a simple heating system, as illustrated in Figure 1, was created based on GenOpt’s example ObjectiveFunction.mo to demonstrate the coupling of OpenModelica and GenOpt.  Figure 1: Model in OpenModelica The models from the Modelica Standard Library (MSL) are the following: Modelica.Blocks.Sources.TimeTable Modelica.Blocks.Sources.Sine Modelica.Blocks.Math.Feedback  Modelica.Blocks.Math.Product  Modelica.Blocks.Continuous.Integrator Modelica.Blocks.Types.Init.InitialState Modelica.Thermal.HeatTransfer.Sources.PrescribedTemperature Modelica.Thermal.HeatTransfer.Components.ThermalConductor Modelica.Thermal.HeatTransfer.Components.HeatCapacitor Modelica.Thermal.HeatTransfer.Sensors.TemperatureSensor Modelica.Thermal.HeatTransfer.Celsius.ToKelvin Modelica.Blocks.Sources.CombiTimeTable  In the model, the Modelica.Thermal.HeatTransfer.Components.HeatCapacitor parameters were as illustrated in Figure 2.   Figure 2: HeatCapacitor Parameters Coupling OpenModelica and GenOpt  4  Set u.y to [1], while connecting Modelica.Blocks.Sources.CombiTimeTable to Modelica.Thermal.HeatTransfer.Celsius.ToKelvin as illustrated in Figure 3.  Figure 3: Creating Connection To verify that there are no modelling errors and the model behaves as intended, please attempt to run the simulation.  Additional Information The working directory path can be changed to the desired location. Click on Tools> Options> General and change the Working Directory path. Set the simulation time to the desired simulation period. Click on simulation> Simulation Setup> General and set the Start Time: and Stop Time: of the simulation in seconds. For example, 24 hours is equivalent to 86400 seconds (secs). The Modelica.Blocks.Sources.CombiTimeTable required a file with data to fill the table, and in the above context it requires a schedule file. In the model verification process, change the fileName path to the “modelicaSchedule.txt” file location. 1.2 EDITING THE MODEL After having created the model, for the model to generate results.txt file the model code must be edited. To view the model code, press on ‘view text’ from the model option bar.  Figure 4: Finding the ‘view text’ option 1.2.1 Load File Command The following command is then used to input the modelicaSchedule.txt and create the result.txt file. In this example, modelicaSchedule.txt is the file name of the schedule used, and the result.txt is the file name of the result file we wish to generate.  Coupling OpenModelica and GenOpt  5  model hsysmodel   parameter String inputFileName = "modelicaSchedule.txt" "File on which data is present";   parameter String resultFileName = "result.txt" "File on which data is present";   parameter String header = "Objective function value" "Header for result file"; * hsysmodel is the model name.  1.2.2 Print Result File After adding the load file command, the following command must be added before the equation to generate the result file. initial algorithm   if resultFileName <> "" then     Modelica.Utilities.Files.removeFile(resultFileName);   end if;   Modelica.Utilities.Streams.print(fileName = resultFileName, string = header); equation  The following code is then added after the equation to add the objective function variable to the result.txt file in the required format.  equation   when terminal() then     Modelica.Utilities.Streams.print("f(x) = " + String(int.y, format = "1.16f"), resultFileName);   end when;   1.3 CREATE A SCRIPT 1.3.1 Script Creation Process After the model is edited to generate a result file, a script is then created to run the model. The script file needs to be able to load the Modelica Standard Library and the model and then be able to simulate the model. The script file should have a ‘.mos’ extension. The ‘.mos’ extension file can be created by simply creating and blank text file and then altering the file extension from ‘.txt’ to ‘.mos’. For the model hsysmodel.mo the following commands were used in the script file. The simulation stop time was set to 86400 seconds (equivalent to 24 hours) and the number of intervals to 86400 so that the simulation interval is every second. loadModel(Modelica); loadModel(hsysmodel); getErrorString(); simulate(hsysmodel,stopTime=86400.00,numberOfIntervals=86400); getErrorString();  For the script file to successfully run once created, the model needs to be copied to the OpenModelica Library. Coupling OpenModelica and GenOpt  6  The file path of the OpenModelica Library depends on where the software was installed, but usually, it is: C:/Program Files/OpenModelica1.17.0-64bit/lib/omlibrary  1.3.2 Run Script (Optional) After having created the script and copied the model file to the OpenModelica Library, using the following command in the command prompter (cmd.exe), the script can be tested. 1. Open the command prompter. 2. Change the working directory to the path where the schedule and script files are located. 3. Run the following command: C:\WorkingDirectory> C:\Progra~1\OpenModelica1.17.0-64bit\bin\omc script.mos 4.  If the script is working, a result.txt file will be generated in the working directory. Note: In some cases, writing Program Files sends an error message:  'C:\Program' is not recognised as an internal or external command, operable program or batch file.  Therefore Progra~1 should be used instead. 2 GENOPT 2.1 COUPLING FILES For GenOpt to work, the following files are needed: • Simulation input template file • Initialisation file • Configuration file • Command file The command file must be in the format as prescribed by GenOpt. The simulation input template file shows the input file structure, such as the combi table schedule. More details on creating the command file can be found in the GenOpt user manual. To allow the simulation file generated by OpenModelica to be optimised by GenOpt, the initialisation file and the configuration file require editing. The command.txt, initialisation.ini and SimulationInputTemplate.txt files need to be in the same folder where the model.mo is located. The folder used in the example was called ‘coupOMG’; therefore, the following files were copied to the folder: • Simulation input template – modelicaSchedule.txt • Initialisation file – GenoptWin.ini • Command file – command.txt The configuration file location is specified in the initialisation file. Therefore, past the configuration.cfg file in the specified location. • Configuration file - OMGWin.cfg Coupling OpenModelica and GenOpt  7  2.2 INITIALISATION FILE The initialisation file contains the following codes: /* GenOpt initialisation file    Operating system: Windows 10    Vladimir Vukovic and Vishak Dudhee    Teesside University    v.vukovic@tees.ac.uk, 24-03-2021 */ Simulation {   Files {     Template {       File1 = OpenModelicaScheduleTemplate.txt;       File2 = script.mos;    File3 = hsysmodel.mo;     }     Input {       File1 = modelicaSchedule.txt;       File2 = script.mos;    File3 = hsysmodel.mo;     }     Log {       File1 = hsysmodel.log;    Path1 = Simulation.Files.Input.Path1;    SavePath1 = Simulation.Files.Input.Path1;     }     Output {       File1 = result.txt;     }     Configuration {       File1 = "..\\..\\..\\cfg\\OMGWin.cfg";     }   }   ObjectiveFunctionLocation{  Delimiter1 = "f(x) =" ;  Name1      = "f(x)";   }   } // end of section Simulation Optimisation {   Files {     Command {       File1 = command.txt;     }   } } // end of configuration file    2.3 CONFIGURATION FILE The configuration file contains the following code: /* GenOpt configuration file for    OpenModelica on Windows 10     Vladimir Vukovic and Vishak Dudhee    Teesside University    v.vukovic@tees.ac.uk, 24-03-2021 */   // Error messages of the simulation program. SimulationError Coupling OpenModelica and GenOpt  8  {     ErrorMessage = "Integration terminated before reaching end point"; }   // Number format for writing the simulation input files. IO {     NumberFormat = Double; }   SimulationStart {   Command = "cmd /x /c \"start /D%Simulation.Files.Input.Path1% /WAIT /MIN C:\\\"Progra~1\"\\OpenModelica1.17.0-64bit\\bin\\omc script.mos \" " ;   WriteInputFileExtension = true; } 3 EXAMPLE – HSYSMODEL 3.1 SCRIPT - COMMAND PROMPTER The script file was created and run using command prompter to validate the script.  C:\Users\Vishak\Documents\GenOpt\coupOMG> C:\Progra~1\OpenModelica1.17.0-64bit\bin\omc script.mos true true "" record SimulationResult     resultFile = "C:/Users/Vishak/Documents/GenOpt/coupOMG/hsysmodel_res.mat",     simulationOptions = "startTime = 0.0, stopTime = 86400.0, numberOfIntervals = 86400, tolerance = 1e-06, method = 'dassl', fileNamePrefix = 'hsysmodel', options = '', outputFormat = 'mat', variableFilter = '.*', cflags = '', simflags = ''",     messages = "stdout            | info    | ... loading \"tab1\" from \"modelicaSchedule.txt\" LOG_SUCCESS       | info    | The initialization finished successfully without homotopy method. LOG_SUCCESS       | info    | The simulation finished successfully. ",     timeFrontend = 0.1563498,     timeBackend = 0.0179131,     timeSimCode = 0.0411051,     timeTemplates = 0.0315496,     timeCompile = 4.1413164,     timeSimulation = 0.1965352,     timeTotal = 4.5850856 end SimulationResult; "Warning: The model contains alias variables with redundant start and/or conflicting nominal values. It is recommended to resolve the conflicts, because otherwise the system could be hard to solve. To print the conflicting alias sets and the chosen candidates please use -d=aliasConflicts. Warning: The initial conditions are not fully specified. For more information set -d=initialization. In OMEdit Tools->Options->Simulation->OMCFlags, in OMNotebook call setCommandLineOptions(\"-d=initialization\"). "    Coupling OpenModelica and GenOpt  9  3.2 OPENMODELICA SIMULATION The hsysmodel.mo was simulated, and the variable int.y and u.y[1] against time were plotted as shown in Figure 5 to identify the simulation’s objective function value.  Figure 5: Simulation output The final objective function value is: f(x) = 7.3941561989593971 3.3 GENOPT OPTIMISATION The model was then optimised through GenOpt, and the cost function decreased as illustrated in Figure 6.  Figure 6: Optimisation result Minimum: f(x*) = 3.4709810240423664  The Discrete Armijo Gradient optimisation algorithm was used with the following variable values: Algorithm{   Main = DiscreteArmijoGradient;   Alpha = 0.5; Coupling OpenModelica and GenOpt  10    Beta  = 0.8;   Gamma = 0.1;   K0    = 10;   KStar = 0;   LMax  = 50;   Kappa = 50;   EpsilonM = 0.05;   EpsilonX = 0.05;   Please Note: The Antivirus installed on the computer was temporarily disabled throughout the process to prevent any interference during optimisation.    

Coupling OpenModelica and GenOpt:Guidelines Version 2.1

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Coupling OpenModelica and GenOpt:Guidelines Version 2.1

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