Digital Mission Engineering (DME): Events and Time Components (Part 4 of 4)

STK Premium (Air) 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.

This lesson requires STK 13.0 or newer to complete in its entirety. If you have an earlier version of the STK software, you can view a legacy version of this lesson.

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
Communications
Analysis Workbench

Problem statement

Across the industry, the digital engineering process is becoming more complex. Systems of systems are changing and updating in different stages of the mission life cycle. In this series, you will address these challenges by creating a fully connected digital thread with a common mission environment at the core. You will design and test a new satellite constellation for persistent, stereo coverage of hypersonic vehicles across the world. You will address this topic in stages: satellite constellations, hypersonic flight, EOIR sensors, communications links, and triggering events and systems. The vision is to integrate the mission environment and operational objectives into the digital thread early and throughout the entire product life cycle. Through digital mission engineering, you are now capable of quickly evaluating the overall mission impact of the smallest change to any component.

Solution

In this last section of the Digital Mission Engineering (DME) series, you will look at event-based operations for mission or test and evaluation planning. You will focus on understanding and relating all the events that occurred from the beginning of the X-43 Hyper-X Research Vehicle (HXRV)'s test flight to when it was tracked, including any information relayed. The first lesson in the series had you create a unique satellite constellation to track and monitor a hypersonic aircraft. The following lesson walked you through building the hypersonic flight and comparing it to a model made using the with ANSYS Fluent^® fluid simulation software. In that lesson, you also created EOIR cameras to image the thermal properties of the X-43 hypersonic vehicle. In the next lesson, you created the communication system to convey the message to the necessary systems. This last section will bring it all together. You will model how the information will be passed from system to system, so the satellites have the opportunity to image the hypersonic aircraft.

What you will learn

Upon completion of this tutorial, you will be able to:

Understand the series of events taking place
Link the relevant events together
Understand the system as a whole

Video guidance

Watch the following video. Then follow the steps below, which incorporate the systems and missions you work on (sample inputs provided).

Downloading the required starter scenario

A partially created scenario for the event and time components portion of the DME series has been provided for you. The scenario is saved as a visual data file (VDF).

Download the zipped folder here: https://support.agi.com/download/?type=training&dir=sdf/help&file=DME_Session4_Starter_AWB_v13.zip
If you are not already logged in, you will be prompted to log in to agi.com to download the file. If you do not have an agi.com account, you will need to create one. The user approval process can take up to three (3) business days. Please contact support@agi.com if you need access sooner.
Navigate to the downloaded folder.
Right-click on DME_Session4_Starter_AWB_v13.zip.
Select Extract All... in the shortcut menu.
Set the Files will be extracted to this folder: path to the location of your choice. The default path is C:\Users\<username>\Downloads\DME_Session4_Starter_AWB_v13).
Click Extract.
Go to the chosen folder.
DME_Session4_Starter_AWB.vdf will be in the extracted folder.

Opening the starter scenario

In this final section of the DME series, you will analyze how all the systems work together. To speed up the analysis, you can load the starter scenario which has been created for you.

Launch the STK application ().
Click Open a Scenario () in the Welcome to STK dialog box.
Browse to location of your extracted VDF file.
Select DME_Session4_Starter_AWB.vdf.
Click Open.

Saving the VDF as a scenario

Save and extract the VDF data in the form of a scenario folder. When you save a VDF in the STK application, it will save in its originating format. That is, if you open a VDF, the default save format will be a VDF (.vdf). If you want to save and extract a VDF as a scenario folder, you must change the file format by using the Save As feature. This will create a permanent scenario file complete with child objects and any additional files packaged with the VDF.

Open the File menu.
Select Save As....
Select the STK User folder in the navigation pane when the Save As dialog box opens.
Select the DME_Session4_Starter_AWB folder.

A scenario folder with the same name as the VDF was created for you when you opened the VDF in the STK application. This folder contains the temporarily unpacked files from the VDF.

Click Open.
Select Scenario Files (*.sc) as the Save as type.
Select the DME_Session4_Starter_AWB Scenario file in the file browser.
Click Save.
Click Yes when the Confirm Save As dialog box opens to overwrite the existing scenario file in the folder and to save your scenario.

When saving a VDF containing external files as a scenario folder, you must extract its contents to the scenario folder the STK application automatically creates for you in the STK User folder. This allows files packaged with the VDF, such as data files, reports, presentations, HTML pages, scripts, spreadsheets, and other files, to unpack to the scenario folder. If you save the VDF as a scenario folder in another location, these additional files will not be included. See the Permanently Extracting a VDF as a Scenario Folder and VDF Setup Considerations pages for more information.

Save () often during this lesson!

Examining the starter scenario

Examine the scenario when it opens.

You should see the hypersonic test flight (discussed in the DME: Hypersonics and EOIR lesson).
You should see the eight relevant satellites from the SBIRS LEO constellation designed in the Constellation Design and Coverage lesson and refined in the Comm Analysis and Antenna Patterns lesson. These satellites are modeling the OmniInstalled transmitters and the Space-Based Infrared System (SBIRS).
New to the mission are three geosynchronous satellites. These satellites are modeling the Defense Support Program (DSP) detection system.

All data and behavior is notional. The systems relate in this manner:

The mission is initiated by the takeoff of a B-52 aircraft carrying the Pegasus Hyper-X Launch Vehicle (HXLV), which accelerates the X-43 Hyper-X Research Vehicle (HXRV).
The DSP satellites in GEO orbit search for rocket plumes (ignition signature).
When the Pegasus HXLV ignites, its burn becomes detectable by the DSP system.
When the burn signature (something big and bright) is detected and processed, the DSP system sends that information to a ground terminal.
The ground terminal receives the information, processes it, and sends it to a constellation of SBIRS LEO satellites. The basis of this constellation is from first lesson, but with modifications that came about as the mission scope was expanded.
The SBIRS satellites have IR cameras on board to track and follow the X-43 HXRV once it has been released from the Pegasus HXLV.
That information is transmitted back down to the ground terminal.
Once this entire system is modeled, you can assess the Total System Response Time, from the rocket ignition to full tracking by the SBIRS LEO satellites.

Adding the Pegasus HXLV burn interval to the Timeline View

The event that triggers the DSP system, and thus the entire series of events, is the burn from the Pegasus HXLV launch. You can add that to the Timeline View to see when it occurs.

Click the Timeline 1 tab in the lower left hand corner of the STK application to unhide the Timeline View.
Right-click on the Timeline View title bar.
Clear the Auto Hide check box. This will keep the Timeline View open.
Click Add Time Components () in the Timeline View toolbar.
Select the HXLV_Pegasus () in the object list when the Select Timeline Component dialog box opens.
Select PegasusBurn () in the Components for: HXLV_Pegasus list.

This component was pre-built in the starter scenario. It has defined start and end time for the duration of the burn.

Click OK to close the Select Timeline Component dialog box.
Look in the component rows section of the Time Display.

Pegasus HXLV Burn

This adds the first time component to the Time Display. This component was built to model the burn of the HXLV as it launches. This is also what the satellites in GEO detecting the burn sees. This is the initial trigger that sets the system in motion. This ignition burn is the initial event that triggers a detection system. It is what sets off the series events.

Click and drag the rectangular markers on either side of the View Port to resize and focus on smaller periods of the scenario, if desired.

Creating a Chain between the DSP system and the Pegasus HXLV

Next, model how quickly the DSP system can detect the Pegasus HXLV burn. Once the Pegasus ignites and launches, the GEO satellites sweep and look for its signature. You can create a Chain between the sensor on a specific DSP satellite and the Pegasus. The sensor on the SBIRS_GEO-3_41937 satellite is in the correct position to detect the HXLV ignition. Using a Chain object, you can perform additional analysis.

Creating a new chain object

Insert a new chain object to model the access from the DSP satellite sensor to the Pegasus HXLV.

Bring the Insert STK Objects tool () to the front.
Select Chain () in the Scenario Objects list.
Select the Insert Default () method.
ClickInsert. . ..
Right-click on Chain1 () in the Object Browser.
Select Rename in the shortcut menu.
Rename Chain1 () to DSP_to_Pegasus.

Defining the start and end objects

Start by choosing the start object and end object in your chain.

Right-click on DSP_to_Pegasus () in the object Browser.
Select Properties () in the shortcut menu.
Select the Basic - Definition page when the Properties Browser opens.
Click the Start Object ellipsis ().
Select dsp_sweep3 (), which is attached to SBIRS_GEO-3_41937 (), in the Select Object dialog box.

This is the specific system that is in the right location to detect the ignition.

Click OK to close the Select Object dialog box.
Click the End Object ellipsis ().
Select HXLV_Pegasus () in the Select Object dialog box.
Click OK to close the Select Object dialog box.

Creating the Chain object's connections

After you choose the start and end objects in your chain, you need to build the chain's connections. It doesn't matter in which order you place the connections in the Connections list. What matters is the From Object must be able to access the To Object.

Click Add in the Connections panel.
Click the From Object ellipsis ().
Select dsp_sweep3 () in the Select Object dialog box.
Click OK to close the Select Object dialog box.
Click the To Object ellipsis ().
Select HXLV_Pegasus () in the Select Object dialog box.
Click OK to close the Select Object dialog box.
Click Apply to accept your changes and to keep the Properties Browser open.

Defining the interval component

This sensor is attached to a satellite. It is spinning and sweeping the sensor over the earth. Through each sweep, the system is triggered when it detects the burn. The interval component models the detection of the burn through each sensor sweep. You can add the burn interval to the chain analysis to make sure you are looking at it during the correct period.

Select the Basic - Advanced page.
Select the User Specified Time Period option in the Compute Time Period panel.
Open the Start Stop drop-down list.
Select Interval Component....
Select the HXLV_Pegasus () in the object list when the Select Time Interval dialog box opens.
Select PegasusBurn () in the Intervals for: HXLV_Pegasus list.
Click OK to close the Select Time Interval dialog box.
Click OK to accept your changes and to close the Properties Browser.

Adding the DSP to Pegasus Complete Chain Access intervals to the Time Display

You can add the time component to the Time Display component rows to see how it compares to the data you have about the Pegasus burn. This interval marks each time the sensor on the SBIRS_GEO-3_41937 is able to scan and detect the burn signature from Pegasus.

Click Add Time Components () in the Timeline View toolbar.
Select the DSP_to_Pegasus () in the object list of the Select Timeline Component dialog box.
Select CompleteChainAccessIntervals () in the Components for: DSP_to_Pegasus list.
Click OK to accept your changes and to close the Select Timeline Component dialog box.

DSP_to_Pegaus Complete Chain Access Intervals

Creating the DSP system processing time duration component

This component shows all the instances when the DSP system on board the SBIRS_GEO-3_41937 satellite can detect the Pegasus burn. However, the system needs to verify that it is detecting a real ignition and process that information before it can relay it to the Ground Station. You can use the Analysis Workbench capability with the chain from the DSP system to the Ground Station while taking the processing time into account.

Adding a new time interval

Create a new time interval to factor into your analysis.

Right-click on DSP_to_Pegasus () in the Object Browser.
Select Analysis Workbench... () in the shortcut menu.
Select the Time tab when the Analysis Workbench opens.
Select DSP_to_Pegasus () in the object list.

You can build the processing time on this chain access.

Click Create new Interval () in the toolbar.

Adding a Fixed Duration time component

You will define a time component that produces a single interval of time.

Click Type: Select... in the Add Time Component dialog box.
Select Fixed Duration () in the Select Component Type list when the Select Component Type dialog box opens.

Fixed duration is an interval of fixed duration anchored at a time defined by a specified Time Instant component.

Click OK to close the Select Component Type dialog box.
Enter DSP_SystProcessing in the Name field.

Adding the processing time

Build the processing time from the first detection of the burn.

Click the Reference Time Instant ellipsis ().
Select DSP_to_Pegasus () in the object list when the Select Reference Time Instant dialog box opens.
Expand () CompleteChainAccessTimeSpan () in the Time Instants for: DSP_to_Pegasus list.
Select Start ().
Click OK to close the Select Reference Time Instant dialog box.
Enter 30 sec in the Stop Offset field.
Click OK to close the Add Time Component dialog box.
Click Close to close the Analysis Workbench.

Adding the DSP system processing time duration component to the Time Display

Add in the interval to the Time Display account for how long the information takes to process on board the SBIRS_GEO-3_41937 satellite and when it is able to react. You built this component so that it is triggered during the first sweep and that it is prepared to relay the information after the third one.

Click Add Time Components () in the Timeline View toolbar.
Select the DSP_to_Pegasus () in the object list in the Select Timeline Component dialog box.
Select DSP_SystProcessing () in the Components for: DSP_to_Pegasus list.
Click OK to accept your changes and to close the Select Timeline Component dialog box.

DSP_to_Pegaus DSP_SystProcessing

Creating a chain between the DSP satellite and the Ground Terminal

After the burn is verified and the information is processed, the next stage is for the SBIRS_GEO-3_41937 satellite to send that signal to the Ground Terminal. You do not have a specific transmitter built on this system, so this analysis focuses on the chain access between the geostationary satellite and the Ground Terminal.