Unlock the Power of FreeFlyer's Optimization

Unlock the Power of FreeFlyer's Optimization

Highlights:

• Introduction to the new optimization functionality added in Free Flyer 7.6
• Demonstration of the optimal lunar gravity assist sample mission plan
• Overview of the optimization capabilities in Free Flyer
• Detailed explanation of the multiple shooting approach used in the mission plan
• Configuration and evaluation of the departure section in the mission plan
• Analysis of the Second optimization process for refining the trajectory
• Integration and visualization of the trajectory using a single spacecraft
• Walkthrough of the output and visualization of the mission plan
• Additional resources for learning more about optimization and Free Flyer
• Availability of technical support for any questions or issues

Table of Contents:

1. Introduction
2. Optimization Functionality in Free Flyer 7.6
3. Optimal Lunar Gravity Assist Sample Mission Plan
4. Overview of Free Flyer's Optimization Capabilities
5. Multiple Shooting Approach in the Mission Plan
6. Configuration and Evaluation of the Departure Section
7. Analysis of the Second Optimization Process
8. Integration and Visualization of the Trajectory
9. Output and Visualization of the Mission Plan
10. Additional Resources and Technical Support

Optimization Functionality in Free Flyer 7.6

Free Flyer 7.6 has introduced new optimization functionality that allows users to perform multi-variable optimization of user-defined objective functions. This functionality opens up a range of possibilities for optimizing mission plans and finding the best solutions.

Optimal Lunar Gravity Assist Sample Mission Plan

To demonstrate the power of the optimization functionality in Free Flyer 7.6, let's take a look at an example mission plan - the optimal lunar gravity assist sample mission plan. This mission plan utilizes the optimization capabilities of Free Flyer to find the minimum delta-v required to insert a spacecraft into a highly elliptical orbit using a lunar gravity assist maneuver.

Overview of Free Flyer's Optimization Capabilities

Free Flyer supports three industry-standard optimizers - SNOPT, IPOPT, and NLopt. SNOPT is a sparse non-linear optimizer, IPOPT is an interior point optimizer, and NLopt is a library for non-linear optimization. While IPOPT and NLopt are included with Free Flyer, users will need to obtain their own SNOP DLL to use it with Free Flyer.

Multiple Shooting Approach in the Mission Plan

The optimal lunar gravity assist sample mission plan utilizes a multiple shooting approach to break down the trajectory into six segments. Each segment is solved using two optimization processes: the first process solves for the departure and lunar flyby, while the second process solves for the final orbital insertion. The results of these two processes are then used to seed a final optimization process that minimizes the overall delta-v required.

Configuration and Evaluation of the Departure Section

The departure section of the mission plan is configured using FreeForm 4. State variables representing the initial Cartesian state of each segment are added, and constraints are defined to ensure the viability of the trajectory. The IPOPT engine is loaded, and a GRID window is set up to display optimization statistics.

In FreeForm 5, the departure section is evaluated. The optimization process is run in a while loop until it converges on a solution. The Cartesian state and epochs of the spacecraft are assigned, and the constraints are checked. The spacecraft is then propagated to patch points, and the difference in Cartesian states is calculated and assigned to constraints. Lastly, the optimizer solve constraints method is called.

Analysis of the Second Optimization Process

The second optimization process, configured in FreeForm 7, builds on the results of the first process. State variables defining the initial state and burn components are added, and constraints are set to guide the trajectory. The feasibility tolerance is adjusted, and the IPOPT engine is loaded. In FreeForm 8, the evaluation loop for the second process is defined, which includes initializing the spacecraft, propagating to patch points, calculating constraint values, and calling the optimizer solve constraints method.

Integration and Visualization of the Trajectory

FreeForm 12 handles the integration and visualization of the trajectory using a single spacecraft. The objects saved from the optimization processes are restored, and the spacecraft is set to use a fixed step size for smoother visualization. The spacecraft's state is assigned using the best state variable values obtained from the optimization, and it is then propagated and maneuvered through the different sections of the trajectory. Finally, the trajectory is visualized using different colors to represent different segments.

Output and Visualization of the Mission Plan

When running the mission plan, the grid window displays optimization statistics, including the values of state variables and constraints. The trajectory is visualized in segments, and as the optimization processes progress, the values in the grid window and visualization are updated. The output layout can be reconfigured to Show the Jacobian values for further analysis and fine-tuning of the optimization process.

Additional Resources and Technical Support

For further learning about optimization and Free Flyer, users can explore the resources available, including videos from the Free Flyer Users Conference. Additionally, the Free Flyer technical support team is always available to assist users with any questions or issues they may have.

FAQ:

Q: What are the optimization capabilities in Free Flyer 7.6? A: Free Flyer 7.6 supports multi-variable optimization of user-defined objective functions using industry-standard optimizers such as SNOPT, IPOPT, and NLopt.

Q: How does the multiple shooting approach work in the optimal lunar gravity assist mission plan? A: The multiple shooting approach breaks down the trajectory into segments and solves them using two optimization processes. The results are then used to seed a final optimization process for further refinement.

Q: Can I use the optimization functionality in Free Flyer without obtaining additional plugins? A: Yes, IPOPT and NLopt are included with Free Flyer. However, users will need to obtain their own SNOP DLL to use it with Free Flyer.

Q: How can I Visualize and analyze the results of the optimization process? A: Free Flyer provides a grid window that displays optimization statistics, as well as visualization tools to visualize the trajectory and the Jacobian values for fine-tuning the optimization process.

Q: Is technical support available for any questions or issues? A: Yes, the Free Flyer technical support team is available to assist users with any questions or issues they may have. Users can reach out to them via email or phone.