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1、Mechanical Simulation912 North Main, Suite 210, Ann Arbor MI, 48104, USATechnical MemoPhone: 734 668-2930 Fax: 734 668-2877 : infoRunning Multiple VS Vehicles in SimulinkThis document describes how multiple vehicles from a VehicleSim (VS) product (BikeSim,CarSim, and TruckSim) can be simulated in a

2、single Simulink m. The example simulation inthis memo is based on some datasets included in TruckSim 7.0; similar examples also exist in CarSim and BikeSim.Example Simulink Mwith Two VehiclesAll of the VS products come with an example Simulink mthat includes two vehicles thatinteract. (See the examp

3、les in the Datasets, category Simulink). For example, TruckSim7.0 includes a Simulink mshowing two vehicles interacting, with the second vehicle usingadaptive cruise control based on the distance between the vehicles. Figure 1 shows a view of the animation.Figure 1. Animation of two-vehicle simulati

4、on example in TruckSim.Any simulation that involves multiple vehicles must have at least one Run Control dataset per vehicle that provides a description of that vehicle. For example, in TruckSim the two vehicles shown in the animation in Figure 1 are associated with two Run Control datasets datasets

5、:··Simulink Multi Vehicles: Cruising First TruckSimulink Multi Vehicles: Cruising Second TruckApril 2, 20081 / 9Before making a new run in Simulink involving multiple vehicles, there is an extra step necessaryafter installing the software from the CD that is not required for ms with just o

6、ne vehicle.Navigate to each run that is referenced in the Simulink m(the two datasets noted above),unlock the screen, and click the Send to Simulink button. After this is done for both datasets, theSimulink misy to run with the two vehicles.Background: Running One Vehicle Min SimulinkRunning a Simul

7、ink mwith just one vehicle is done with a high level of automation betweenSimulink and a VS browser such as TruckSim. Working with multiple ms requires that someof the information set automatically for one mmust instead be set manually.1234Figure 2. Simulink mwith one VS vehicle m.Before going into

8、thes of the two-vehicle example, the technical discussion will begin witha description of how the browser sets up runs in Simulink involving a single vehicle. For2 / 9NoteThe run can be initiated from Simulink, or from either TruckSim run screen using the Run from Here button.example, consider the S

9、imulink ABS mincluded in TruckSim that is shown in Figure 2.(Similar ABS ms are also included in BikeSim and CarSim.)VS products such as TruckSim include a group of DLL solver program files, each optimized for a specific multibody vehicle configuration involving nonlinear suspension types, the numbe

10、r of axles, the number of trailers, and other factors. The multibody configuration is identified by a vehicle code, associated with the vehicle dataset. For example, in Figure 2 the vehicle dataset linkshows that the vehicle code for the selected vehicle is s_s. (This code represents a 2-axle1vehicl

11、e with solid-axle suspensions front and rear.) The s_s code was sent automatically to theSimulink mby the TruckSim browser, and is shown under the TruckSim S-Function block, and also in the Function Block Parameters window.23The Function Block Parameters window shows a second parameter: the name of

12、a simulationcontrol file (simfile). The default name for this file is simfile.4The operation of a VS solver program is described in the VehicleSim Solver Programs ReferenceManual. When running under Windows OS, the program that runs the simulations a simfilethat identifies a dynamically linked libra

13、ry (DLL) file that is then loaded to access the VS solver suitable for the specified run.Listing 1 shows the contents of simfile for the example run from Figure 2. (The listing includes line numbers to support the following discussion.) Line 7 identifies the DLL file for the vehicle as C:Program Fil

14、esTruckSim_ProgProgramsSolversDefault s_s.dll.Listing 1. Example simfile for a single vehicle simulation.When the Simulink m automatically:(an MDL file) is opened by Simulink, several things happen1.Simulink queries the VS S-Function block (e.g., the TruckSim S-Function) to determine the number of i

15、nput and output variables and other properties of the block.2.In response to the query from Simulink, the VS S-functions the simfileidentified as a function block parameterand finds the global pathname for a DLL4file identified by the keyword DLLFILE (see line 7 in Listing 1).The S-Function loads th

16、e DLL file identified in step 2, and invokes a function from3.the DLL called vs_configuration that is part of the VS applicationprogram interface (VS API). This function takes the name of the simfile as an input,and then scans the simfile to obtain the name of a mparameter input file(parsfile), iden

17、tified by the keyword INPUT (see line 2 in Listing 1).3 / 91. SIMFILE2. INPUT C:TruckSim_DataRunsRun193_all.par3. ECHO C:TruckSim_DataRunsRun193_echo.par4. FINAL C:TruckSim_DataRunsRun193_end.par5. LOGFILE C:TruckSim_DataRunsRun193_log.txt6. ERDFILE C:TruckSim_DataRunsRun193.erd7. DLLFILE C:Program

18、FilesTruckSim_ProgProgramsSolversDefaults_s.dll8. END4.The VS API function continues tothe parsfile identified in step 3, obtaining allparametric information from the VS database (e.g., TruckSim) associated with thecurrent run. This includes the number of variables imported into the block and the nu

19、mber of variables exported from the block.5.The VS API function vs_configuration provides the number of importand export variables to Simulink, which then checks for compatibility with the inputand output controls that are set in the Simulink m then Simulink generates an error message.). (If they ar

20、e not compatible,6.Simulink sends a terminated to the S-Function block. The S-function theninvokes a corresponding VS API function vs_terminate and unloads the VS DLL.Whenever a run is initiated, either from Simulink or the VS browser, the S-Function loads theDLL file again, repeating steps 3 and 4

21、above. Thus, the simfile is alwaysat least twice for arun: once to determine the number of import and export variables when Simulink defines itsinternal representation of the m, and a second time when the run starts.It is common to change vehicle properties or run conditions from the VS browser afte

22、r a Simulinkmiivated. If this is done, the Send to Simulink button should be clicked so the browserwill update the parsfile and simfile used by Simulink.Considerations with Multiple Vehicle MsThe VS browser is designed to automatically load the appropriate VS solver from the family of DLL files if r

23、un with no other software, or to communicate with other software (e.g, Simulink) with a full pathname for the specific DLL file that should be loaded. All of the information from the VS database is provided to the DLL via an input parsfile that is specified in a simfile, which is automatically gener

24、ated whenever initiating a run or sending information to other software.The VS solvers are designed be loaded and run from many environments, so the main considerations for running multiple vehicles is to set up an independent solver for each vehicle, with an associated independent parsfile, referen

25、ced by an independent simfile.Multiple VS DLL FilesA VS solver DLL is intended to represent a single vehicle, and cannot represent two independent vehicles at the same time. (At any given time, the Windows OS will load a specific DLL file only once. If a program specifies that the DLL should be load

26、ed again, the OS simply returns a pointer to the existing location in memory.)When there is a need to simulate two vehicles at the same time, based on the same VS configuration (e.g., s_s), then a simple method for defining a new independent simulation mis to make a copy of the DLL with a different

27、name (e.g., s_s2.dll) and load the copy. Even though the contents of the second DLL are identical to the original, the Windows OS will handle them as being completely independent.Multiple Simfiles and ParsfilesIn normal operation with a single vehicle, the VS solver writes a new simfile in the curre

28、nt working directory (the root folder of the VS database) that references a parsfile generated from the currently active Run Control dataset.4 / 9If two separate vehicles are to be simulated simultaneously, then each needs a separate simfileand parsfile. A simple way to set up multiple vehicle ms th

29、at can run at the same time is tocreate a separate Run Control dataset to represent each vehicle, as described for the TruckSim example below.The Adaptive Cruise Control Example in TruckSim: the Second VehicleFigure 3 shows one of two Run Control datasets that connected to a Simulink mused tosimulat

30、e two vehicles that interact through an adaptive cruise control. Clicking on the Send toSimulink buttonbrings up a Simulink mthat has two TruckSim S-Function blocks.2Double-click on a block to see the associated parameters, as was done in Figure 3 for the secondblock. The two parameters for the bloc

31、k are the vehicle code(s_s2)and the simfile name56(simfile2). Listing 2 shows the contents of simfile2. Note that the DLL file that is7named in line 7 is compatible with the vehicle code s_s2 shown in Figure 3 for Simulink (5and), but not for the linked vehicle dataset in the Run Control screen. The

32、 automatic61copying of the code from the Run Control screen will not work here: the code must be set manually for each vehicle S-Function block.2134567Figure 3. Example Simulink mwith two trucks that interact.5 / 9Listing 2. Simfile2 for TruckSim adaptive cruise control (second vehicle).Clicking on

33、the blue link under the run control buttons transfers to the Simulink m the second vehicle, shown in Figure 4.screen for12345678Figure 4. Ms: Simulink screen for second vehicle in TruckSim example.As with any Ms: Simulink dataset, the name of the MDL file is specified, along with1links to datasets t

34、hat specify variables for importand exportrelative to the Simulink78m.In this case, some advanced features are also used.The name of the simfile is also specified on this screen to be simfile2. (Thed for6defining the name of a simfile is the keyword simfile, followed by the name.) Therefore, whenthe

35、 Send to Simulink button (in Figure 3) is clicked, the file created is simfile2 rather2than the default simfile. This name is set to match the name that was put in the TruckSimBlock Parameters fieldin Figure 3.76 / 91. SIMFILE2. INPUT c:TruckSim_DataRunsRun204_all.par3. ECHO c:TruckSim_DataRunsRun20

36、4_echo.par4. FINAL c:TruckSim_DataRunsRun204_end.par5. LOGFILE c:TruckSim_DataRunsRun204_log.txt6. ERDFILE c:TruckSim_DataRunsRun204.erd7. DLLFILE c:TruckSim_DataExtensionsMulti_Vehicles_s2.dll8. ENDThere are no restrictions for the name of the simfile, except that it cannot contain any charactersth

37、at would be illegal for a Windows file name. To avoids, it is recommended that asimfile that is linked to a datset such as this should have a unique name, so it will not be inadvertently overwritten. There is nothing magical about the name simfile2; in the example that come with TruckSim there are o

38、nly two datasets that specify non-default simfile names, and those names are simfile1 (for the first vehicle in this example) and simfile2.The checkbox for specifying alternative solver files is checked, causing a pull-down control4to be displayed for setting the number of vehicle types that will be

39、 associated with alternativesolver files. In this case, the control is set to 1, causing data fields to be shown for one vehicle5codeand one pathname. The settings in these fields indicate that when a vehicle is23selected on the Run Control screen with code s_s, then the associated DLL file is to be

40、2. This relative pathname is converted to anExtensionsMulti_Vehicless_s2.dll3absolute pathname when writing simfile2 (see line 7 in Listing 2). The file name is set to becompatible with the vehicle code set for the Function Block Parameters fieldin Figure 36If we want to change the name of the eithe

41、r the simfile or the DLL file, then a matching changemust bein the Ms: Simulink screen (Figure 4) and also for the Function BlockParameters window (Figure 3).The Adaptive Cruise Control Example in TruckSim: the First VehicleA separate Ms: Simulink dataset is used for the first vehicle in the Simulin

42、k m, and isshown in Figure 5.As with the Ms: Simulink dataset from Figure 4, the Simulink MDL file is identified.1The defauLL file for the vehicle (s_s.dll) can be used, and therefore the checkbox to use adifferent solver file is not checked, and the advanced controls shown in Figure 4 are not2visib

43、le. The only remaining pieces of information are the name of the simfile associated with thisvehicle (simfile1), and a set of output variables that will be provided by this mto3Simulink.47 / 9Note In the example datasets provided with the TruckSim 7.0 CD and CarSim7.01 CD, the simfile specification

44、3 shown in the above figure is instead located in the misc. yellow field on the Run Control screen, as was done for the simfile name for the second vehicle.Note In the example datasets provided with the TruckSim 7.0 CD and CarSim7.01 CD, the simfile specification 6 shown in the above figure is inste

45、ad located in the misc. yellow field on the Run Control screen. Both locations are equally valid. However, the location described in this memo is recommended because it places most of the information needed to define a separate vehicle m on the same dataset: the screen shown in Figure 4.1234Figure 5

46、. Ms: Simulink screen for first vehicle in TruckSim example.Summary of Method for Simulating Multiple VehiclesTeral method for building a Simulink mthat involves two or more vehicles can now besummarized.1.Each vehicle min the Simulink m(an MDL file) must be represented by a copyof the vehicle S-Function block provided with the VS package. (E.g., the TruckSim S- Function for TruckSim). For example, in Figure 3, there are two copies of this block.2.Each vehicle must be def