Formation Design GUI

Since version 7.

Contents

Introduction

This tool enables you to simultaneously design the geometry and
organize the team structure of a spacecraft formation. It supports
formations in circular or eccentric orbits about a central body.

The GUI is divided into two windows. The right-side window shows
the trajectories of the specified satellites in the relative frame.

The left-side window is organized into the following 6 control panels:
   - Satellite
   - Orbit Data
   - Geometry
   - Team Structure
   - Display
   - Relative State

The usage of each panel is covered in individual sections of this
help file.

Team Roles and Organization

The FormationDesign GUI may be used to organize a satellite cluster
into teams.

Every member of a team has a role. One satellite serves as the
"reference", which defines the origin of that team's relative frame. All
other team members are considered "relatives". In addition, one of the
satellites serves as the team captain. Because it does not impact the
formation geometry, however, the role of captain is not included in
the GUI.

Several teams may be "bridged" together by letting the relative of one
team also serve as the reference of another team. When bridging teams
together, it is important to avoid circular references. Logical checking
is performed by the GUI to ensure that this does not occur.

The 6 Control Panels

Each satellite is identified by a unique integer ID number. This number
is assigned when the satellite is added to the cluster.

At any given time, ONE SATELLITE in the cluster is selected. The selection
is made using the pull-down menu located at the top of this panel. The
information displayed in the "Geometry" and "Relative State" panels
corresponds to the selected satellite.

You may wish to assign the selected satellite to a team. To do so, push
the "Assign To Team" button. You will be shown a list of candidate teams.
If the selected satellite is already on a team, the current team is not
included in the list of candidates. In addition, some logical checking is
done to prevent circular references. In particular, if the selected satellite
is a reference for a team, then only those teams that are NOT BELOW it are
shown.

Once a team is selected, the satellite is then assigned to that team, and
the GUI displays are updated. The "Team Structure" panel is modified to
reflect the change, the Team and Reference display in the "Satellite" panel
are changed, and the trajectory for the selected satellite is recomputed
and plotted.

The elements may be changed at any time. Changing any of the elements
OTHER than the mean/true anomaly will cause the entire relative
trajectory to change. Changing just the mean/true anomaly will simply
change the current location of the satellite on its relative trajectory.

The relative trajectories for the cluster will not be recomputed
automatically after changing the reference orbit. They will be recomputed
only when the "Update All" button is pushed in the "Geometry" panel.

Every satellite has a relative trajectory. The trajectory is defined by
a set of geometric parameters, which can be entered in this panel.

Once a satellite is selected, its geometric parameters are displayed.
The parameter set is summarized below:
   + y0        Along-track (y) center of in-plane motion
   + xMax      Maximum radial amplitude
      - nu     True anomaly at which xMax occurs
   + zMax      Maximum cross-track amplitude
      - nu     True anomaly at which zMax occurs

The parameter set may be used to define the relative motion with respect
to either the cluster reference or the team reference. The choice of
reference may be made by using the pull-down menu near the bottom of
this panel. The "Team" option may be selected only if the satellite is a
member of a team.

When you are satisfied with your changes to the geometry, press the
"Update" button. This will cause two things to happen:
   1) The relative state will be updated and displayed
   2) The relative trajectory will be recomputed and plotted

Push the "Update All" button if you would like to update ALL of the
satellite's trajectories at once. This should be done if you have made
changes to the "Orbit Data" panel.

This panel allows you to create and delete teams, and it shows the
overall team structure.

Press the "Create" button to create a new team. You will be asked
to choose a satellite to be the reference. Only those satellites in the
cluster that are NOT ALREADY a reference may be selected. Once you have
chosen a reference, you must then enter a team name. Any alpha-numeric
string is acceptable. Do not enter single quotes in the name.

Once you have created a team, it will be shown in the hierarchical list
at the top of the panel. Clicking on the team will show the ID numbers
of all members. The reference is shown with (R) beside it.

You may view a graphical representation of the team structure by
pressing the "VIEW" button. It will bring up a new window that displays
each team according to its hierarchical level in the cluster.

If one or more teams exist, you may assign satellites to teams from
the "Satellite" panel.

The "Display" panel gives you several options for affecting how the
relative trajectories are plotted.

You can choose to plot just the selected satellite, all of the
satellites on its team, or the entire cluster. Do this by using the
radio buttons in the "Plot" sub-panel.

You can quickly snap the view of the axes to one of four 2D planes.
Just use the four buttons in the upper-right-hand corner of the panel.

You can animate the motion of all displayed satellites over the course
of one orbit by pressing the "Animate" button.

Finally, you can change the origin of the displayed relative frame by
using the Reference pull-down menu. Either the Cluster or the Team
reference may be chosen.

The relative state may be viewed as either orbital element differences,
or as Hill's frame position and velocity. The relative state shown is
directly related to the geometric parameters entered in the "Geometry"
panel.

Zooming

You can zoom in and out of the plot by using shortcut keys.

CTRL + I will zoom in.

CTRL + O will zoom out.

This can be useful when adding a trajectory that is much bigger than
the original axes.

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Published with MATLAB® R2021b