Aerospace and Electronic Systems - April 2019 - 33

Di Tana et al.

Figure 6.
IS1 target confirmation.

Figure 5.
ArgoMoon mission profile.

with the SLS's program requirements and European
Cooperation for Space Standardization standards. The
ArgoMoon satellite has to deal with constraints that
most CubeSats have not yet dealt with: ArgoMoon will
operate outside the Earth's magnetic field, crossing
the Van Allen radiation belts multiple times during its
operational lifetime.
In order to match these constraints, the ArgoMoon
platform relies on novel technologies for CubeSat applications, since two of the main subsystems (OBC&DH and
EPS) have been fully designed by Argotec to match the
constraints of a Deep Space radiation environment linked
to the small amount of available volume inside the structure; furthermore, the core part of the OBC&DH is the IS
Algorithm aimed at processing, tracking, and identifying
the targets in the FoV of the cameras.
The IS is aimed at processing the picture acquired with
the vision unit of the PL, in order to recognize multiple
objects (Earth, Moon, Sun, and the ICPS as a worst case
scenario) in the FoV and support autonomously proximity
flight around the ICPS; since it is not a mission objective,
the IS is not able to recognize the CubeSats while they are
being deployed from the ICPS. The main target to be identified is the ICPS of the SLS: the identification of the ICPS
will make it possible to track and maintain it in the center
of the FoV, thus allowing ArgoMoon to take detailed pictures in accordance with the mission goals. The IS has to
be considered as a series of cascading algorithms that,
despite being extremely different from each other, cooperate in order to acquire the consciousness of the framed
objects: the results are sequentially processed and shared
starting from IS1, the simplest of the three.
The ArgoMoon algorithms for image recognition can,
therefore, be divided into three sets [14]:

IS1 merges the information commanded to the OBC
for the shooting with the pictures' metadata and it gives
confirmation the target is in view, providing the On-board
Software with the feedback on the presence of objects in
the camera's FoV, by comparing the luminance channel
with respect to a threshold evaluated from the OBC.
Once the object is confirmed to be in view and the
rough position has been estimated, each photograph is filtered and analyzed to detect the center of area of the target
and the associated dispersion; IS2 is able to ensure the
level of pointing required by the mission, i.e., 0.01 deg
with respect to the target.
An MTI algorithm has been developed: this algorithm
allows ArgoMoon to identify multiple targets, label them
and calculate their estimated centers of areas and dispersion (with IS2 performances): the starfield is filtered,
while only the three main objects are considered (see
Figure 7). After this identification, different solutions can
be applied in order to select the proper target: since the
dimensions of the ICPS are much smaller than those of
the other objects in the camera's FoV, the first object to be
pointed is the one with the lowest number of pixels in the
FoV; if the object is not recognized as the ICPS, the OBC
commands the ADCS to point the second object with the
lowest number of pixels, and so on.
For all the IS strategies, once the target is detected,
the target pointing vector is computed and sent to the
ADCS via the OBC&DH-ADCS link in the shape of a

 IS1 - Visual Confirmation the object is in view and
rough pointing (see Figure 6);
 IS2 - Fine Pointing and Multiple Target Identification (MTI);
 IS3 - Target Confirmation.
APRIL 2019

Figure 7.
Multiple target identification.

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