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Projecte llegit

Títol: Onboard Computer for 3CAT-NXT

Estudiants que han llegit aquest projecte:

Director/a: PARK, HYUK

Departament: FIS

Títol: Onboard Computer for 3CAT-NXT

Data inici oferta: 21-07-2022     Data finalització oferta: 21-03-2023


Estudis d'assignació del projecte:
    GR ENG SIST AEROESP
Tipus: Individual
 
Lloc de realització:
UPC
    Departament: CommSensLab
 
Nom del segon director/a (UPC): Adriano Camps, Stefan Podrau
Departament 2n director/a:
 
Paraules clau:
PocketQube, UPC NanoSat Lab, Space Engineering, On-Board Computer
 
Descripció del contingut i pla d'activitats:
PocketQubes concept appeared as an alternative for earth
observation with smaller and cheaper LEO nanosatellites. Its
modular behaviour allowed limited budget institutions to be part
of space missions and thereby space exploration advances faster.
This document includes the OBC tasks that have been performed at
the 3CAT-NXT PocketQubes mission tackled by the NanoSat Lab. The
main purpose of OBC is to manage the data flow between the
following subsystems: ADCS, COMMs, PAYLOAD1, PAYLOAD2 and EPS.
The OBC tasks focus on agglutinating the whole code from other
subsystems into a mainframe so as to test everything at once with
a flatsat. In order to do that, some existing problems related to
low power modes and interruptions had to be fixed. Parallel to
the main focus, the usage of the stack size had to be checked
with 4048 bytes available.
 
Overview (resum en anglès):
Due to an increasing entry barrier to both universities and researchers in conventional small satellites initiatives, there has been an emergence of smaller and cheaper spacecrafts like PocketQubes, a much more affordable option for public entities. Considering all that, this thesis has been developed as part of a project undertaken by the UPC NanoSat Lab which started as an IEEE GRSS initiative named PoCat. The objective of the PoCat project is to design, develop and test three single unit picosatellites with each featuring the following different payloads, a Video Graphics Array (VGA) camera, a Radio Frequency Interference (RFI) monitoring system at L-band and an RFI monitoring system at K-Band. The three satellites, however, contain the same avionics core composed of the On-Board Computer (OBC), Communication System (COMMS), Attitude Determination and Control System (ADCS) and Electrical Power Supply System (EPS).

Given this scenario, the purpose of this report is to give insights regarding the on-board software development for PocketQubes, which as of writing this report there is still room for debate concerning their standardization. Conceptually, the OBC system acts as the brain of the satellite. As for the technology, the OBC is build upon the STM32L476 microcontroller due to its memory storage, power efficiency and processing power.

Performing the power management as well as giving response to events are the main objectives of the OBC. In order to do the latter, the flight software is based on a Real-Time Operating System (RTOS) called FreeRTOS which has been selected above other Operating System (OS) due to its predictability, compliance with the required
deadlines, support, available documentation, compatibility with previous projects, licensing
costs, and certifications.

According to FreeRTOS, the program is structured into independent tasks where each one features a priority in line with their criticality. Then, the project is constituted by eight tasks, with five designed to operate the subsystems of the satellite, one for memory writing purposes and the remaining two are devoted to implement FreeRTOS software timers. Furthermore, tasks can communicate with each other by means of task notifications or event groups, both being software tools provided by the operating system.

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