Part 7: Customize Analysis with Analysis Workbench

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

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 STK Capabilities:

  • STK Pro
  • Analysis Workbench

Problem Statement

Engineers and technicians require additional capabilities when using STK to create custom functions and calculations relative to times, positions, and reference frames. You work at a ground station that tracks a recently launched satellite. The ground station's sensor must be turned off when its boresight is within 10 degrees of the Sun. You need a report that tells you when it's safe to track the satellite.

Solution

Use a combination of STK Pro and STK's Analysis Workbench capability to create vectors, custom angles, calculations, time components and temporal constraints to determine when the sensor can safely track the satellite.

What You Will Learn

Upon completion of this tutorial, you will understand the following Analysis Workbench Tools:

Video Guidance

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

Create a New Scenario

Create a new scenario.

  1. Launch STK ().
  2. Click Create a Scenario ().
  3. Enter the following in the New Scenario Wizard:
    4. Option Value
    Name: STK_AnalysisWorkbench
    Location: Default
    Start: 1 Mar 2021 16:00:00.000 UTCG
    Stop: + 2 days
  4. Click OK when you finish.
  5. Click Save () when the scenario loads. A folder with the same name as your scenario is created for you in the location specified above.
  6. Verify the scenario name and location.
  7. Click Save.

Disable Terrain Server

Terrain is not required for this analysis. Disable the Terrain Server.

  1. Right- click on STK_AnalysisWorkbench () in the Object Browser.
  2. Select Properties ().
  3. Select the Basic - Terrain page.
  4. Clear the Use terrain server for analysis check box.
  5. Click OK to accept the changes and close the Properties Browser.

Satellite Tracking Station

Insert a Facility object which will act as a satellite tracking station.

  1. Select Facility () in the Insert STK Objects tool.
  2. Select the Insert Default () method.
  3. Click Insert....
  4. Right-click on Facility1 () in the Object Browser.
  5. Select Rename.
  6. Rename Facility1 () Tracking_Station.

Recently Launched Satellite

Insert a Satellite object which will be tracked by the tracking station.

  1. Select Satellite () in the Insert STK Objects tool.
  2. Select the Orbit Wizard () method.
  3. Click Insert....
  4. Set the following in the Orbit Wizard:
    5. Option Value
    Type: Circular
    Satellite Name: New_Sat
    Inclination: 50 deg
    Altitude: 800 km
    RAAN: -85 deg
  5. Click OK.

Calculate Access

Calculate the times the tracking station can access or see the satellite using the Access tool. This access will be used as a component when using the Analysis Workbench.

  1. Right-click on Tracking_Station () in the Object Browser.
  2. Select Access ().
  3. Select New_Sat () in the Access Tool's Associated Objects list.
  4. Click Compute ().
  5. Look at the Timeline View. By default the Timeline View is docked at the bottom of the STK GUI.
  6. Note the multiple accesses between Tracking_Station () and New_Sat ().
  7. Click Close to close the Access tool.

Vector Geometry Tool

The Vector Geometry Tool (VGT) offers the ability to build custom geometric models from any combination of out-of-the box or user-created Vector (), Axes (), Point (), System (), Angle () and Plane () components.

Open Tracking Station's Properties

Open Tracking_Station's () 3D Graphics - Vector Properties page. We will select vectors to display in the 3D Graphics window.

  1. Open Tracking_Station's () properties ().
  2. Select the 3D Graphics - Vector page.
  3. Select the Vectors tab.

Display Sun Vector

You will display the Sun Vector. In this scenario, the Sun Vector is anchored to tracking station's center point and targets the Sun.

  1. Select the Sun Vector Show check box.
  2. Click Apply to accept the changes and keep the Properties Browser open.

Show Sun Vector

View the Sun Vector in the 3D Graphics window.

  1. Bring the 3D Graphics window to the front.
  2. Right-click on Tracking_Station () in the Object Browser.
  3. Select Zoom To.
  4. Zoom out far enough so that you can see the Sun vector.
  5. Click Start () to animate the scenario in the Animation toolbar. The Sun Vector follows the Sun.
  6. Click the Reset () when you are finished.

Show To Vector

A To Vector is a displacement vector between origin and destination object points. To Vectors are automatically generated by STK for all objects in your scenario. The vectors are stored in a separate folder labeled, To Vectors, unless a vector with the same name already exists (Earth or Sun). In scenarios with many objects, the To Vectors folder can be very large for each object. View the New_Sat's () To Vector.

  1. Return to Tracking_Station's () 3D Graphics - Vector properties () page.
  2. Select the Vectors tab.
  3. Click Add....
  4. Click the Expand () button beside To Vectors () in the Components for: list on the right of the Add Components window.
  5. Select New_Sat.
  6. Click OK to close the Add Components window.

Show Magnitude

If Show Magnitude is selected, the magnitude value is displayed on the selected vector. This is only available for vectors (). Show the magnitude for New_Sat's () To Vector.

  1. Return to Tracking_Station's () properties () .
  2. Ensure New_Sat Vector is selected in the Vectors list on the 3D Graphics - Vector page.
  3. Select Show Magnitude.
  4. Click Apply.

View To Vector

View the To Vector and the Magnitude in the 3D Graphics window.

  1. Bring the 3D Graphics window to the front.
  2. Click Start () in the Animation toolbar to animate the scenario.

    3. The New_Sat Vector may be below the surface of the central body because the satellite is below the horizon but will eventually surface. The vector follows the satellite. Show Magnitude provides a constant distance between the tracking station and the satellite, dynamically, in the 3D Graphics window.

  3. Click the Reset () when you are finished.

Create a Custom Angle

Create an angle () between the Sun Vector and the New_Sat To Vector. For the purposes of this scenario, whenever the angle is 10 degrees or less, the satellite tracking system needs to be shut down.

Open Analysis Workbench Tools

Open the Analysis Workbench Tools, and select the Vector Geometry tab.

  1. Right-click on Tracking_Station () in the Object Browser.
  2. Select Analysis Workbench ().
  3. Select the Vector Geometry tab.
  4. Ensure Tracking_Station () is selected in the Object list.
  5. Click Create new Angle () to open the Add Geometry Component window.

Create a Between Vectors Angle

Select the Between Vectors angle type. You will create an angle between the Sun Vector and the New_Sat Vector.

  1. Ensure the Type: is set to Between Vectors. This is the default Type.
  2. Enter TrackingAngle in the Name: field.

Select the From Vector

Select New_Sat's () To Vector as the From Vector. The custom angle, TrackingAngle, will be measured starting from New_Sat's To Vector.

  1. Click the ellipsis button () beside the From Vector: field. The Select Reference Vector window opens.
  2. Select Tracking_Station () in the Objects list.
  3. Scroll up in the Vectors for: Tracking_Station list on the right.
  4. Click the Expand () button beside To Vectors ().
  5. Select New_Sat.
  6. Click OK to close the Select Reference Vector window.

Select the To Vector

Select the Sun Vector as the To Vector. The custom angle, TrackingAngle, will be measured between the New_Sat's To Vector and the Sun vector.

  1. Return to the Select Reference Vector window.
  2. Note that To Vector: already has the Tracking_Station Sun vector selected.
  3. Click OK to close the Add Geometry Component window.
  4. Note the TrackingAngle vector is in My Components ().
  5. Keep the Analysis Workbench () open.

Display the Custom Angle

Custom angles can be viewed in the 3D Graphics window. Add the custom tracking angle to Tracking_Station's () 3D Graphics - Vector Properties page.

  1. Return to Tracking_Station's () properties ().
  2. Select the 3D Graphics - Vector page.
  3. Select the Angles tab.
  4. Click Add....
  5. Select TrackingAngle in the My Components () folder in the the Components for: list.
  6. Click OK to close the Add Components window.
  7. Note Show is selected for TrackingAngle.
  8. Click OK to accept the changes and close the Properties Browser.

View Tracking Angle

View the tracking angle in the 3D Graphics window.

  1. Bring the 3D Graphics window to the front.

    2. Vectors and Angle View

  2. Click Start () in the Animation toolbar to animate the scenario.
  3. Note as the scenario animates, the angle increases and decreases, updating dynamically.
  4. Click the Reset () when you are finished.

Calculation Tool

The Calculation Tool includes components of the following basic types: Scalar (), Condition () and Parameter Set (). Use the Calculation Tool to determine when the tracking angle is 10 degrees or less.

Scalar

You will create a Scalar to return the tracking angle values. A scalar defines components that produce scalar time-varying calculations. Scalar calculation components also have the ability to return minimum, maximum, mean, and standard deviation values. You will start by creating a new Scalar Calculation ().

  1. Return to the Analysis Workbench ().
  2. Select the Calculation tab to open the Calculation Tool.
  3. Select Tracking_Station () in the Object list.
  4. Click Create new Scalar Calculation () to open the Add Calculation Component window.

Define Scalar Calculation

The default scalar calculation type is Angle. The Angle type is an angular displacement specified by an Angle component from the Vector Geometry Tool.

  1. Ensure the Type: is set to Angle. This is the default Type.
  2. Enter Scalar_TrackingAngle in the Name: field.
  3. Click the ellipsis () beside the Input Angle: field. The Select Reference Angle window opens.
  4. Select Tracking_Station () in the Objects list.
  5. Select TrackingAngle in the My Components () folder in the Angles for: Tracking_Station list.
  6. Click OK to close the Select Reference Vector window.
  7. Click OK to close the Add Calculation Component window.
  8. Note Scalar_TrackingAngle is in My Components ().

Condition

Conditions define a scalar calculation which is considered to be satisfied when it is positive and not satisfied when it is negative. Create a Condition () to report when the tracking angle is 10 degrees or less.

Create a Condition

Create a new Condition ().

  1. Return to the Analysis Workbench () Calculation tab.
  2. Select Tracking_Station () in the Object list.
  3. Click Create new Condition () to open the Add Calculation Component window.

Define Calculation Condition Type

The default Calculation type is Scalar Bounds. Scalar Bounds defines a condition by combining a specified Scalar component with scalar bounds.

  1. Ensure the Type: is set to Scalar Bounds. This is the default Scalar Bounds.
  2. Enter Below_10_Degrees in the Name: field.

Define the Scalar

Set the Scalar Calculation, Scalar_TrackingAngle, as the Reference Scalar Calculation.

  1. Click the ellipsis () beside the Scalar: field. The Select Reference Scalar Calculation window opens.
  2. Select Tracking_Station () in the Objects list.
  3. Select Scalar_TrackingAngle in the My Components () folder in the Scalar_TrackingAngle for: Tracking_Station list.
  4. Click OK to close the Select Reference Scalar Calculation window.

Define the Calculation Conditions

Define the calculation conditions.

  1. Select Below Maximum in the Operation drop down list.
  2. Enter 10 deg in the Maximum: field.
  3. Click OK to close the Add Calculation Component window.

Create a Report

You can create reports and graphs directly inside the Calculation Tool. Create a report showing when the tracking angle is below 10 degrees.

  1. Return to the Analysis Workbench () Calculation tab.
  2. Select Tracking_Station () in the Objects list.
  3. Expand () Below_10_Degrees in the My Components () Components for: list.
  4. Right-click on SatisfactionIntervals.
  5. Select Report.

    6. The report shows when the tracking angle is 10 degrees or less during the entire scenario interval. However, it doesn't restrict the report to those times when there are accesses between the tracking station and the satellite.

  6. Close () the report.
  7. Keep the Analysis Workbench () open.

View Accesses and Satisfaction Intervals in the Timeline View

The Timeline View can be used to visualize a variety of time intervals within your scenario. Use the Timeline View to visualize the times Tracking_Station () has access to New_Sat () and the times the tracking angle is less than 10 degrees.

  1. Return to the Analysis Workbench ().
  2. Select SatisfactionIntervals under Below_10_Degrees in the My Components () Components for: list.
  3. Drag and drop SatisfactionIntervals into the Timeline View's Time Display.

    4. Accesses and Below 10 Degree Satisfaction Intervals

  4. Observe the Timeline View.

    5. Can you see any times when the tracking angle is below 10 degrees and might interrupt accesses?

Time Tool

Use the Time Tool to create and manage any time instant(), interval (), interval list (), collection of interval lists () or time array (). Create an interval list to show when Tracking_Station () has access to New_Sat () while the tracking angle is above 10 degrees.

Create an Interval List

Using the Time Tool, you will create a custom Interval List () by merging access times and the below 10 degree satisfaction intervals. Subtract the below 10 degree satisfaction intervals from the accesses to define tracking opportunities.

  1. Return to the Analysis Workbench ().
  2. Select the Time tab.
  3. Select Tracking_Station () in the Object list.
  4. Click Create new Interval List () to open the Add Time Component window.
  5. Enter Optimal_Tracking_Times in the Name: field.

Define the Interval List Type

Create a Merged Interval List. Merged Interval Lists are intervals merged from multiple Interval or Interval List Time Components using a merge operation.

  1. Click Select... beside the Type: field.
  2. Select Merged () in the Select Component Type window list.
  3. Click OK to close the Select Component Type window.

Define the Operation

Define the merge operation as Minus. Subtract the below 10 degree satisfaction intervals from the accesses to define tracking opportunities. The Minus operation is available when there are only two Time Components in the merge list.

  1. Return to the Add Time Component window.
  2. Select MINUS in the Operation drop down list.

Remove Time Components

Remove default time components.

  1. Select the first time component in the Time Components: list.
  2. Click Remove.
  3. Repeat the above steps until all time components are removed.

Define the Time Components

In this instance, there are two time components: the accesses between the tracking station and the satellite and the below 10 degree satisfaction intervals.

  1. Click Add... to open the Select Time Intervals window.
  2. Select Facility-Tracking_Station-To-Satellite-New_Sat () in the Object list.
  3. Select AccessIntervals in the Installed Components () Components for: list.
  4. Click OK to close the Select Time Intervals window.
  5. Click Add... on the Add Time Component window.
  6. Select Tracking_Station () in the Object list.
  7. Expand () Below_10_Degrees in the My Components () Components for: list.
  8. Select SatisfactionIntervals.
  9. Click OK to close the Select Time Intervals window.
  10. Click OK to close the Add Time Component window.

View Intervals in the Timeline View

You now have all the components for your analysis completed. View them in the Timeline View.

  1. Return to the Analysis Workbench () Time tab.
  2. Select Optimal_Tracking_Times in the My Components () Components for: list.
  3. Drag and drop Optimal_Tracking_Times into the Timeline View's Time Display.

    4. Timeline View Showing All Time Components

  4. Observe the Timeline View to see the merged intervals.
  5. Return to the Analysis Workbench ().
  6. Click Close.

Tracking Station Sensor

Attach a Sensor object () to the tracking station to track the satellite. Then, using the custom components created in this lesson, model an outage on the sensor when the tracking angle goes below 10 degrees.

Insert a Sensor on Tracking Station

Insert a sensor object on the tracking station.

  1. Select Sensor () in the Insert STK Objects tool.
  2. Select the Define Properties () method.
  3. Click Insert....
  4. Select Tracking_Station () on the Select Object window.
  5. Click OK .

Model Limited Field-of-View

Set a limited field of view for the sensor to provide situational awareness.

  1. Select the Basic - Definition page.
  2. Ensure the Sensor Type: is set to Simple Conic. This is the default type.
  3. Enter 2 deg in the Cone Half Angle: field.
  4. Click Apply .

Target the Sensor

Use the Targeted pointing type to point the sensor at the satellite.

  1. Select the Basic - Pointing page.
  2. Select Targeted in the Pointing Type: drop down list.
  3. Select New_Sat () in the Available Targets list.
  4. Click Move () to move New_Sat () to the Assigned Objects list.
  5. Click OK.
  6. Rename Sensor1 () Tracking_Sensor.

Calculate Access

Compute an access between the sensor () and the satellite ().

  1. Right-click on Tracking_Sensor () in the Object Browser.
  2. Select Access ().
  3. Select New_Sat () in the Access Tool's Associated Objects list.
  4. Click Compute ().
  5. Click Access... in the Reports section.
  6. Note the multiple accesses between Tracking_Station () and New_Sat ().
  7. Keep the Access tool () and the report open.

Add Temporal Constraints

You want to know when the tracking station's sensor accesses the satellite, but restrict access when the sensor's boresight is within 10 degrees of the Sun. You can do this by adding a Temporal Constraint to your sensor object using the custom components created earlier in this lesson.

  1. Open Tracking_Sensor's () properties ().
  2. Select the Constraints - Temporal page.
  3. Select Use in the Intervals section.
  4. Click Import... to open the Select Time Intervals window.
  5. Select Tracking_Station () in the Object list.
  6. Select Optimal_Tracking_Times in the My Components () Components for: list.
  7. Click OK to close the Select Time Intervals window.
  8. Note the intervals have populated in the Intervals list.
  9. Click OK to close the Properties Browser.

Create a New Access Report

Create a new access report to compare the original access report with the constrained report.

  1. Return to the Access tool ().
  2. Click Access... in the Reports section.
  3. Compare your original access report's Total Duration with the constrained access report's Total Duration.
  4. Note the temporal constraint shortens your access time.
  5. Note the times in the access report are the times your sensor can safely access the satellite.

    6. Temporal Constraint Total Duration Comparison

Solar Exclusion Angle

What you have built and used in this lesson is a Solar Exclusion Angle. Set that directly in the sensor constraints.

  1. Open TrackingSensor's () properties ().
  2. Select the Constraints - Temporal page.
  3. Disable the Use option in the Intervals list.
  4. Select the Constraints - Sun page.
  5. Enable the Boresight - Solar Exclusion Angle.
  6. Set the value to ten (10) deg.
  7. Click OK to close the Properties Browser.

The access times update and just like before, you can see the times that your sensor can safely access the satellite.

Save Your Work

  1. Close any open reports, properties and tools which are still open.
  2. Save () your work.

Summary

This tutorial focused on three tools that are available in the Analysis Workbench:

  1. Vector Geometry Tool
  2. Time Tool
  3. Calculation Tool

In this lesson:

  • You inserted a tracking station and a low earth orbit (LEO) satellite.
  • Created an access between the tracking station and the satellite.
  • Displayed the tracking station's Sun and satellite's To Vector in the 3D Graphics window.
  • Used the Vector Geometry tool to create a custom angle between the vectors.
  • Used the Calculation tool to create a scalar using the tracking angle and then a condition which reported when the angle was 10 degrees or less.
  • Used the Time tool to create an interval list by merging the access intervals with the below 10 degrees satisfaction intervals. Subtracting the below 10 degrees satisfaction intervals from the access intervals created the optimal tracking times for your system.
  • Attached a sensor to the tracking station and targeted the sensor to the satellite.
  • Created a constrained interval by importing the optimal tracking times into the sensor's properties. This caused the Access tool to only report accesses during the optimal tracking times. The final report can be used to know when it is safe to tracking the satellite with the sensor.

On Your Own

Throughout the tutorial, hyperlinks were provided that pointed to in depth information. Now's a good time to go back through this tutorial and view that information.

Further training using the Analysis Workbench:

  • STK Training: Look at the License Required column. All lessons with Analysis Workbench are lessons which use the Analysis Workbench.