Part 10: Performing Trade Studies with ModelCenter

STK Premium (Air), STK Premium (Space), or STK Enterprise
You can obtain the necessary licenses for this tutorial by contacting AGI Support at support@agi.com or 1-800-924-7244.

Required product install: The Ansys ModelCenter® model-based systems engineering software and the STK Plugin for ModelCenter are required to complete this tutorial. The ModelCenter software is available through the Ansys Universal Installer and the STK Plugin for ModelCenter is included with the STK Premium installation. Contact AGI support for installation help.

ModelCenter installation prerequisites: The ModelCenter software installs the current version of Java and Python supported by Ansys, but you can also use your own versions. See the Installation instructions in the ModelCenter Installation Guide and Supported Versions documentation for more information. Contact AGI support for help with installation.

This tutorial was written using version 2026 R1 of the Ansys ModelCenter® model-based systems engineering software. Refer to the ModelCenter Supported Versions page in the ModelCenter Installation Guide and Supported Versions documentation for compatibility information.

The results of the tutorial may vary depending on the user settings and data enabled (online operations, terrain server, dynamic Earth data, etc.). It is acceptable to have different results.

Capabilities covered

This lesson covers the following capabilities of the Ansys Systems Tool Kit® (STK®) digital mission engineering software:

  • STK Pro
  • Coverage
  • STK Analyzer

Problem statement

Engineers and operators require an easy way to determine how a satellite's orbital parameters, such as its semi-major axis, eccentricity, inclination, argument of perigee, right ascension of the ascending node (RAAN), and true anomaly affect the ability an onboard sensor or camera to view the surface of the Earth. You want to quickly run multiple trade studies to determine how the inclination, RAAN, and the combination of both will affect the percentage of coverage time over four geographic areas during a seven-day analysis period. You require a minimum of 20 seconds of coverage time over four selected regions.

Solution

Use the STK software's Coverage capability and the Analyzer capability, which is part of the Ansys ModelCenter® model-based systems engineering software, to perform both a parametric and a carpet plot trade study. These will determine the combination of inclination and RAAN that provides the highest percentage of coverage time.

What you will learn

Upon completion of this tutorial, you will understand:

  • How to wrap an STK scenario with the STK Plugin for ModelCenter
  • How to use the Analyzer capability
  • How to perform trade studies in the ModelCenter software

Creating a new scenario

First, you must create a new scenario, then build from there.

  1. Launch the STK application ().
  2. Click Create a Scenario in the Welcome to STK dialog box.
  3. Enter the following in the New Scenario Wizard:
    4. Option Value
    Name STK_ModelCenter
    Location Default
    Start Today
    Stop + 7 days
  4. Click OK when you finish.
  5. Click Save () when the scenario loads.

    6. The STK software creates a folder with the same name as your scenario for you.

  6. Verify the scenario name and location in the Save As window.
  7. Click Save.

Save () often during this tutorial!

Cleaning up your workspace

You can view coverage in both the 2D and 3D Graphics windows. Closing the Timeline View and placing the graphics windows side by side makes this simple to do.

  1. Close () the Timeline View at the bottom of the STK application window.
  2. Select the Window menu in the Menu Bar.
  3. Select Tile Vertically.

Your 2D and 3D Graphics windows will fill the integrated workspace.

Turning off streaming terrain

Analytical and visual terrain is not required in this analysis, so you can turn off streaming terrain from the Terrain Server.

  1. Right-click on STK_ModelCenter () in the Object Browser.
  2. Select Properties () in the shortcut menu.
  3. Select the Basic - Terrain page when the Properties Browser opens.
  4. Clear the Use terrain server for analysis check box in the Terrain Server panel.
  5. Click OK to confirm your change and to close the Properties Browser.

Inserting a Satellite object

Propagate a notional Satellite object into a circular orbit using the Orbit Wizard method.

  1. Bring the Insert STK Objects tool () to the front.
  2. Select Satellite () in the Select An Object To Be Inserted list.
  3. Select Orbit Wizard () in the Select A Method list.
  4. Click Insert....
  5. Enter My_Sat in the Satellite Name field when the Orbit Wizard opens.
  6. Leave the rest of the default settings.
  7. Click OK to propagate My_Sat into a circular orbit and to close the Orbit Wizard.

Circular orbits have a constant radius.

Attaching a Sensor object to My_Sat

Use a Sensor object to model a camera with a ten-degree field of view.

  1. Bring the Insert STK Objects tool () to the front.
  2. Insert a Sensor () object using the Define Properties () method.
  3. Select My_Sat () when the Select Object dialog box opens.
  4. Click OK to confirm your selection and to close the Select Object dialog box.
  5. Note that the default Sensor Type is set to Simple Conic when the Properties Browser opens.

    6. A Simple Conic sensor pattern is defined by a simple cone angle, measured in terms of the cone half angle.

  6. Set the Cone Half Angle to 5 deg.

    7. A five-degree half angle means the sensor has a ten-degree field of view.

  7. Click OK to confirm your change and to close the Properties Browser.
  8. Right-click on Sensor1 () in the Object Browser.
  9. Select Rename in the shortcut menu.
  10. Rename Sensor1 () Camera_View.

Inserting four Area Target objects

You are interested in analyzing coverage over Iran, Nigeria, North Korea, and Russia. Insert four Area Target objects, which you will use to concentrate your coverage analysis in those selected areas, using the Select Countries and US States method.

  1. Bring the Insert STK Objects tool () to the front.
  2. Insert an Area Target () object using the Select Countries and US States () method.
  3. Clear the US States check box in the List Selections panel when the Select Countries And US States dialog box opens.

    4. By default, the list displays both countries and US states.

  4. Multi-select Iran_Islamic_Rep, Korea_Dem_Rep, Nigeria, and Russian_Federation in the list on the left.
  5. Leave the Primary Area Only option selected in the Insert panel.

    6. The STK application creates Area Target objects from shapefiles, which contain one or more polygons. It converts each polygon into one Area Target object. If the shapefile for the selected area contains two or more polygons, you can choose whether to add only the largest polygon (Primary Area Only) or all polygons (All Areas) in the shapefile. By selecting this option, you will ignore islands and territories.

  6. Click Insert.

    7. This will create four separate Area Target objects, one for each region.

  7. Click Close to close the Select Countries And US States dialog box.

Using the Coverage capability

The STK software's Coverage capability allows you to analyze the global or regional coverage provided by one or more assets while considering all available accesses. To address area coverage, the Coverage capability provides you with two STK object classes: Coverage Definition objects and Figure of Merit objects.

Inserting a Coverage Definition object

You want to assess coverage over the four selected regions. To do this, you will use a Coverage Definition object to model the areas that you will analyze. Coverage Definition objects enable you to define and maintain an area of coverage, to define the STK objects providing coverage for the area (such as satellites, aircraft and sensors), to define the time period of interest, and to calculate accesses to the region(s).

  1. Bring the Insert STK Objects tool () to the front.
  2. Insert a Coverage Definition () object using the Insert Default () method.
  3. Rename CoverageDefinition1 () Area_Cov.

Defining the coverage grid

Coverage analyses are based on the accessibility of assets (that is, the objects that provide coverage) and geographical areas. For analysis purposes, you can further refine the geographical areas of interest using regions and points. Define the coverage area to include Iran, North Korea, Nigeria and Russia by selecting their Area Target objects. Area Target objects used to define custom regions should have a longitude span no greater than 180 degrees. This limitation includes area targets encompassing a polar region.

  1. Open Area_Cov's () Properties ().
  2. Select the Basic - Grid page when the Properties Browser opens.
  3. Open the Type drop-down list in the Grid Area of Interest panel.
  4. Select Custom Regions.
  5. Open the drop-down list under Custom Regions.
  6. Select Area Targets.
  7. Multi-select Iran_Islamic_Rep (), Korea_Dem_Rep (), Nigeria () and Russian_Federation () in the Area Targets list.
  8. Move () Iran_Islamic_Rep (), Korea_Dem_Rep (), Nigeria () and Russian_Federation () from the Area Targets list to the Selected Regions list.
  9. Enter 1 deg in the Lat/Lon field in the Point Granularity panel.

    10. When using custom regions, it is important to select adequate point granularity. If a single custom region is smaller than the resolution, the STK application will generate an alternative grid using a finer granularity to ensure at least three samples within the region.

  10. Click Apply to confirm your changes and to keep the Properties Browser open.

Selecting the coverage assets

Assign Camera_View as your coverage asset. The Coverage Definition object's Assets properties enable you to specify the STK objects used to provide coverage.

  1. Select the Basic - Assets page.
  2. Expand () My_Sat () in the Assets list.
  3. Select Camera_View ().
  4. Click Assign.
  5. Click OK to confirm your changes and to close the Properties Browser.

Attaching a Figure of Merit object

The STK software enables you to specify the method by which the quality of coverage is measured using a Figure Of Merit object.

  1. Bring the Insert STK Objects tool () to the front.
  2. Insert a Figure Of Merit () object using the Insert Default () method.
  3. Select Area_Cov () when the Select Object dialog box opens.
  4. Click OK to confirm your selection and to close the Select Object dialog box.
  5. Rename FigureOfMerit1 () Cov_Time.

Measuring Coverage Time

Set the Figure Of Merit object to Coverage Time. Coverage Time measures the amount of time during which grid points are covered. Because Coverage Time does not have a dynamic definition, no time-dependent information is computed.

  1. Open Cov_Time's () Properties ().
  2. Select the Basic - Definition page when the Properties Browser opens.
  3. Open the Type drop-down list in the Definition panel.
  4. Select Coverage Time.
  5. Open the Compute drop-down list.
  6. Select Total.

This will compute the amount of time (over the entire coverage interval) during which a point is covered.

Selecting satisfaction criterion

You can restrict the Figure Of Merit behavior so that the STK application only reports the static value of the Figure Of Merit when it meets specified satisfaction criteria. You desire a minimum coverage time of 20 seconds for each point in the grid. You want to determine the percentage of grid points that meet this criterion.

  1. Select the Enable check box in the Satisfaction panel.
  2. Open the Satisfied if drop-down list.
  3. Select At Least.

    4. This criterion for satisfaction will be met when the Figure Of Merit value is greater than or equal to a defined threshold at which satisfaction is achieved.

  4. Enter 20 sec in the Threshold field.
  5. Click OK to confirm your changes and to close the Properties Browser open.
  6. Save () your scenario.
  7. Close the STK application.

Creating a new ModelCenter project

The Ansys ModelCenter model-based systems engineering software is designed for multidisciplinary analysis and design optimization. It allows you to automate complex workflows, integrate multiple engineering tools, and optimize designs within model-based systems engineering (MBSE) frameworks. By wrapping tools and analysis programs like the STK software and running them in an automated fashion, the ModelCenter software makes the design process more efficient, saves engineering time, and reduces the chances for error in the design process. It implements MBSE processes flexibly; its drag-and-drop graphical user interface can be used to assemble tools into a complete engineering workflow, which can contain branches, loops, logical statements, and more. Your workflow can contain tools that run on any number of different machines and operating systems. Once a repeatable engineering analysis process is created, you can repeatedly execute the process, using parallel computing resources if available. Each execution corresponds to a different set of inputs, which you can explore and quantify the performance of your design alternatives in a relatively short time.

  1. Open the ModelCenter () application.
  1. Click Start a New Model in the Welcome to ModelCenter dialog box.
  2. Click Process when the What type of model would you like to create? dialog box opens.

    3. A Process is a graphical, flowchart-like workflow that explicitly tells the ModelCenter application what order (and under what conditions) to run each component. Links between variables have no influence on the execution.

  3. Navigate to your scenario folder (for example, C:\Users\<username>\Documents\STK_ODTK 13\STK_ModelCenter.
  4. Enter STK_ModelCenter in the File name field.
  5. Ensure the Save as type is set to the ModelCenter Model (Zip) (*.pxcz).
  6. Click Save.

You can learn more about the ModelCenter software here.

Configuring the STK Plugin for ModelCenter

All ModelCenter workflows are built using a simple drag-and-drop scheme for creating a graphical layout of a complex analysis. Process workflows leverage that capability by highlighting "hot spots" for adding and moving components in a workflow. Components encapsulate an analysis or control function. Each component exposes input and output variables and executes a run method to transform inputs into outputs. The STK Plugin for ModelCenter is a component plugin that allows the ModelCenter application to directly link to the STK application. It imports a copy of the desired Scenario and opens it in an instance of the STK application. Instantiate the plugin by adding it to your workflow's Analysis View, which displays an overview of the integrated workflow, from the Server Browser, which resides at the bottom of the ModelCenter window and is used to browse for components that can be used in a ModelCenter workflow.

  1. Select favorites () in the Server Browser at the bottom of the window.

    2. Note that your empty Process workflow contains a single hot spot, represented by a dashed circle, in the Analysis View.

  2. Click and drag the STK component () from the Server Browser onto the hot spot, represented by a dashed circle underneath "Drop items here to build the model" in your workflow's Analysis View.

    3. The STK component is an Analysis component; this type of component performs calculations and is usually connected to some external program like the STK application.

  3. Select STK_ModelCenter.sc when the Open STK Scenario file dialog box opens.
  4. Click Open.

This will open the STK scenario and STK Analyzer windows. Please be patient.

The STK_ModelCenter scenario file will open in the STK application in the background. If the STK application opens in front of ModelCenter, bring the ModelCenter window to the front.

Setting up your analysis with Analyzer

Use the STK Analyzer window to configure the input and output variables available for further analysis with the Analyzer capability. You can add almost any STK variable as ModelCenter input or output variables. If you change the value of a variable in your scenario through the STK interface or the ModelCenter Component Tree, you should re-add the variable into ModelCenter or re-run the workflow before running any trade studies with the new value.

Selecting the Analyzer input variables

Your Parametric study will focus on two of the satellite's orbital parameters: Inclination and RAAN. Before you can use them in your model, however, you must first add them to your design space.

  1. Select My_Sat () in the STK Variables tree.

    2. When you select an object in the STK Variables tree, all possible input variable candidates for that object are listed under the General tab and the Active Constraints tab in the STK Property Variables panel.

  2. Expand () the Propagator (J4Perturbation) () property in the STK Property Variables tree.
  3. Move () the following input variables () to the Analyzer Variables list:
    • Inclination
    • RAAN
  4. Note that both variables are listed as Inputs in the Analyzer Variables list.

Selecting the output variables

The same data providers that are available in the Report & Graph Manager in the STK application are available in the Data Provider Variables tree.

  1. Expand () Area_Cov () in the STK Variables tree.
  2. Select Cov_Time ().
  3. Expand () the Static Satisfaction () data provider in the Data Provider Variables tree.
  4. Move () the Percent Satisfied data provider element () to the Analyzer Variables list:
  5. Note that the variable is listed as and Output in the Analyzer Variables list.

    6. STK Analyzer variables

  6. Click OK to confirm your selections and to close the STK Analyzer window.

This will also close the STK application, which had been running in the background. Note that the Analysis View now contains an STK component, which is shown as a box in the Analysis View window.

Analyzing the impact of inclination on coverage

The ModelCenter software features a suite of trade study tools to help you create and analyze your workflows. A trade study is a structured exploration of a workflow by running many designs and collecting the resulting data. Trade studies systematically vary inputs and record responses, allowing you to understand a design space, compare alternatives, and identify optimal or robust designs. Once a workflow is built, these exploration tools can drive it without knowing how the results are computed; essentially, they treat a workflow as a black box, repeatedly getting and setting variables until an objective is met or a plan of experiments is complete. Trade study results can then used to visualize and understand significant trends and trade-offs.

You want to understand how My_Sat's inclination affects its ability to monitor the four regions. Create a Parametric Study to plot the inclination against the coverage time per day.

Creating a benchmark

You can quickly analyze your current setup, which will create a benchmark of the output variable values. The ModelCenter Component Tree, on the left side of the ModelCenter window, shows a hierarchical view of your workflow. It lists each component and its variables, lets you view or edit values, and gives a quick view of the variable state, including invalid input and output variables. Expanding a component shows its variables.

  1. Expand () all the components in the Component Tree.

    2. expanded component tree

  2. Note the variable values in the Component Tree.

    3. These are the values imported into the ModelCenter application from the STK_ModelCenter scenario. Input variables, like Inclination (), you can change. Output variables, like Percent_Satisfied (), are calculated and supplied by the component. In this case, Percent_Satisfied () is invalid, meaning that it has not yet been calculated. The ModelCenter application keeps track at all times of which variables are valid and which are invalid.

    You can optionally display a Units column by right-clicking on the Component Tree's header row and selecting Units in the shortcut menu.

  3. Click Run () on the Standard toolbar.
  4. When completed, note that Percent_Satisfied's icon has changed from invalid () to valid (), and it now has a new value, which has been calculated by the STK component.

The output variable value is based on the default input variables. Overall, you want to reach the highest percent coverage on all points in the three Area Target objects. You are analyzing this coverage for seven days. Obviously, if you were looking for long-term data, you would extend your analysis period.

Using the Parametric Study tool

The Parametric Study tool runs a workflow through a sweep of values for some input variable. You can plot the resulting data to view trends.

  1. Click Parametric Study () on the Standard toolbar.
  2. Click and drag the Inclination () input variable from the Component Tree to the Design Variable field when the Parametric Study tool opens.
  3. Set the following Design Variable values:
    4. Option Value
    starting value 45
    ending value 78
    step size 3
  4. Click and drag the Percent_Satisfied () output variable from the Component Tree to the Responses field.
  5. Click Run.

Clicking Run will open the Data Explorer, which is a tool used by Trade Study tools to display data while they are being collected from your Model. While data are being collected, the Data Explorer displays a progress meter, a halt button, and the data.

Creating a 2D Line Plot

Once the trade study is complete and all data have been collected, the Data Explorer toolbar becomes active. The Data Explorer stores values for all variables in a workflow and special variables from the trade study. Some trade study tools will automatically launch a default plot window when the trade study runs. For other plots, you can create them from the Add View menu. For this study, you will create a 2D Line Plot. A 2D Line Plot displays an X-Y plot for variables in your model. Any variable in the workflow can be plotted against any other variable.

  1. Bring the Data Explorer to the front when the when the trade study is finished running.
  2. Click Add View () on the Data Explorer toolbar.
  3. Select 2D Line Plot () in the drop-down menu.

Setting options for the axes

Use the Axes tab to set options for the axes.

  1. Click Axes () in the Plot Options menu on the left-hand side of the 2D Line Plot.

    2. The Axes tab is used to set options for the plot's axes.

  2. Select the Ticks tab.

    3. The Ticks tab is used to set the display of ticks along the axes.

  3. Change the Max # value to 30.
  4. Click anywhere on the plot to close the Plot Options menu.
  5. Review the 2D Line Plot.

    6. maximum seconds vs. Inclination

    Your plot will look different than the one shown above.

  6. Hover your cursor over the highest data point in the plot.

    7. This will show you information about that point in a Design Tooltip.

  7. Click the Open Design View ellipsis in the lower-right corner of the Design Tooltip to open the Design View dialog box.

    8. This provides more detailed information of the selected point.

  8. Close the Design View dialog box.

    9. Looking at the 2D Line Plot, the highest point will provide the maximum coverage time during the seven day analysis period. In the above image, 66 degrees provides the maximum coverage time.

  9. Note the highest point in the plot.

    10. You will use this value when you run a Carpet Plot trade study.

Closing out your trade study

Close out your trade study for the next section.

  1. Bring the Data Explorer to the front.
  2. Close the Data Explorer.
  3. Click No when prompted to close your trade study without saving.

    4. This will also close all open plots and graphs.

  4. Leave the Parametric Study tool open.

Updating the Inclination input variable for further study

The closer the inclination is to the highest value noted from the Parametric Study, the better your percentage of coverage will be. Set the inclination value to that value for future studies so you can better understand the effects that RAAN has on coverage.

  1. Click into the Inclination () Value field in the Component Tree.
  2. Enter the highest value seen from the last trade study.
  3. Select the Enter key to set the Inclination value.

Analyzing the impact of RAAN on coverage

The satellite's RAAN might impact your coverage.

Running a new Parametric Study

Build a new Parametric Study using the satellite's RAAN as your Design Variable.

  1. Click and drag the RAAN () input variable from the Component Tree to the Design Variable field when the Parametric Study tool opens.

    2. This will replace Inclination as the Design Variable.

  2. Set the following Design Variable values:
    3. Option Value
    starting value 0
    ending value 360
    step size 30
  3. Click Run.

Reviewing data in the Data Explorer Table

While you can create line plots that are great for presentations or personal choice, you can also obtain the required information directly from the Table page. The Table page of the Data Explorer displays trade study data in a tabular form. It is the default window that is present for all trade studies. Cells are shaded differently depending on the associated variable's state. Input variables are shown with green text, valid values are displayed with black text, invalid values are displayed with gray text, and modified values are displayed with blue text. From the table it is possible to view and edit all values in your trade study and even to add and remove whole runs.

  1. Bring the Data Explorer to the front when the when the trade study is finished running.
  2. Examine the results in the Data Explorer Table on the Table Page.
  3. Right-click on the dependent (output) variable (Model.STK_ODTK13.STK_ModelCenter.Area_Cov_Time.Overall_Value.Maximum) in the AUTO SCROLL LIST in the Data Explorer Table.
  4. Select Sort Runs in the shortcut menu.
  5. Select Descending in the Sort Runs submenu.
  6. Move the slide bar at the bottom of the Data Explorer all the way to the left so that you can see the first run.

    7. Data Explorer Table

    Your image will be different from the above image. Note that the title of the list is now MANUAL SCROLL. The very first run in the Data Explorer Table will be the run with the highest percentage of coverage time. In the above image, a RAAN of 150 degrees provides the highest percent of coverage time during the seven-day analysis period.

  7. Note the best RAAN value.
  8. Close the Data Explorer.
  9. Click No when prompted to close your trade study without saving.
  10. Close the Parametric Study tool.

Using the Carpet Plot tool to study inclination and eccentricity together

A Carpet Plot is a means of displaying data dependent on two variables in a format that makes interpretation easier than normal multiple curve plots. A Carpet Plot can be thought of as a multidimensional Parametric Study. Setting the design variables in a Carpet Plot is similar to using the Parametric Study tool, except you can study two variables simultaneously instead of one.

Creating a new Carpet Plot

Set up a Carpet Plot with inclination and RAAN as the Design Variables and Maximum as the response.

  1. Click Carpet Plot () on the Standard toolbar to access the Carpet Plot tool.
  2. Click and drag Inclination () from the Component Tree to the first Design Variables field when the Carpet Plot tool opens.
  3. Set the following Inclination Design Variable values:
    4. Option Value
    From 10 degrees below your best Parametric Study value
    To 10 degrees above your best Parametric Study value
    Step Size 5
  4. Click and drag RAAN () from the Component Tree the second Design Variables field.
  5. Set the following RAAN Design Variable values:
    6. Option Value
    From 0
    To 360
    Step Size 60
  6. Click and drag Percent_Satisfied () from the Component Tree to the Responses field.
  7. Click Run.

The number of runs is determined by the number of steps multiplied by the number of steps. Smaller step sizes will give you much more precise data, but will take a lot longer. Please be patient.

Configuring the Carpet Plot's axes

Using the Carpet Plot tool, look for the best combination of inclination and eccentricity. First, make the Carpet Plot easier to read by adjusting its axes, then review the plot.

  1. Bring the Carpet Plot to the front.
  2. Click Axes () in the Plot Options menu.
  3. Select the Lines tab.
  4. Change the Grid Lines value to 10.
  5. Select the Ticks tab.
  6. Change the Max # value to 30.
  7. Click anywhere on the plot to close the Plot Options menu.

Looking at the carpet plot, you can get an idea of which RAAN and Inclination combination provides the highest percentage of coverage.

Determining the best RAAN and Inclination combination

Sometimes, a carpet plot can be difficult to read. You can create a 3D Scatter Plot to better understand your results. A 3D Scatter Plot displays an X-Y plot of variables in the workflow.

  1. Click Add View () on the Carpet Plot toolbar.
  2. Select 3D Scatter Plot () in the drop-down menu.
  3. Click Axes () in the Plot Options menu.
  4. Select the Ticks tab.
  5. Change the Max # value to 30.
  6. Click anywhere on the plot to close the Plot Options menu.
  7. Hold your left mouse button down and rotate the plot until you find the highest point.

    8. Turntable rotation () is selected by default in the View Controls menu, allowing you to spin the around its middle point, but with its Z axis constrained to not flip.

  8. Click on the highest point to select it.

    9. A point can be selected in any plot; that same point will be selected in any other plots created from the same data set. It's possible that you could have two points with the exact same percentage of coverage time. For instance, if a RAAN of 0 degrees has the best value, then mostly likely, 360 degrees will provide the same data.

  9. Hover your cursor over the selected plot.

    10. 3D Scatter plot with Design Tooltip

    This will provide information on the selected point in a Design Tooltip. As with the 2D Line Plot, you can also open the Design View dialog box to see the data in tabular form.

  10. Bring the Carpet Plot to the front.

Carpet plot best value

Your carpet plot will be different than the one shown above. There will be a small orange dot that corresponds to the selected point in the 3D Scatter Plot. The point can be unselected by clicking it again in either plot.

Based on the Carpet Plot and the 3D Scatter Plot shown above, an inclination of 71 degrees and a RAAN of 210 degrees provides the best percentage of coverage during the seven-day analysis period.

You can find the exact value for this run in the Data Explorer table.

Closing out your trade study

Close out your trade study for the next section.

  1. Bring the Data Explorer window to the front.
  2. Close the Data Explorer window.
  3. Click No when prompted to close your trade study without saving.

    4. This will also close all open plots and graphs.

  4. Close the Carpet Plot tool.

Saving your work

Save your work and close out ModelCenter application.

  1. Close out any open, plots, tools, and the Data Explorer window.
  2. Click No when prompted to close your trade study without saving.
  3. Click Save () to save your ModelCenter workflow.
  4. Close the ModelCenter application.

Summary

You created a base scenario, propagating a nominal Satellite object in a circular orbit and attached a Sensor object with a five-degree half angle field of view. You inserted four Area Target objects that outlined Iran, Nigeria, North Korea and Russia. You inserted a Coverage Definition object, selected the Area Target objects for the grid and the Sensor object as an asset. You attached a Figure Of Merit object to the Coverage Definition object and focused on coverage time and a satisfaction of 20 seconds. Using the STK Plugin for ModelCenter and the ModelCenter software, you ran two Parametric studies to determine the Inclination and RAAN values the highest percentage of coverage that reached the 20-second satisfaction. You ended by creating a Carpet Plot that refined your Parametric values to determine the overall best combination of Inclination and RAAN values.