Projecte llegit
Títol: Contribution to Attitude Orbit Control System (AOCS) for CubeCat-8
Estudiants que han llegit aquest projecte:
- NAVARRO SIMONI, POL EDUARD (data lectura: 14-02-2023)
- Cerca aquest projecte a Bibliotècnica
Director/a: PARK, HYUK
Departament: FIS
Títol: Contribution to Attitude Orbit Control System (AOCS) for CubeCat-8
Data inici oferta: 17-07-2022 Data finalització oferta: 17-03-2023
Estudis d'assignació del projecte:
- GR ENG SIST AEROESP
Tipus: Individual | |
Lloc de realització: |
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Nom del segon director/a (UPC): Adriano Camps | |
Departament 2n director/a: | |
Paraules clau: | |
CubeSat, UPC NanoSat Lab, Space Engineering, Attitude Determination and Control System | |
Descripció del contingut i pla d'activitats: | |
' Brief description of the CubeCat-8
CubeCat-8 is a mission which will be achieved with the union of NanoSat Lab from Universitat Politècnica de Catalunya (UPC), as the team leader, Institut d'Estudis Espacials de Catalunya (IEEC), as contributor with 3Cat-Gea provider and i2Cat, as contributor with software for Federated Satellite Systems experiment. The platform selected would be a Standard 6U ISIS platform. The payload is meant to be formed by the following technology demonstrators: - Deployable Fresnel Zone Plate (FZP) antenna - 2 X 1P PocketQube deployer - Federated Satellite Systems experiment - X-band transmitter - IENAI electric thruster system with electrospray technology. And the following scientific payloads: - Polarimetric hyperspectral camera + data compression - GNSS-Radio Occultations (using deployable FZP deployable reflector) ' Brief description of the AOCS System, the AOCS parts to be implemented at CubeCat8 and the tasks expected for implementation of CubeCat-8 AOCS system The objective of the AOCS system is to provide the mission with controllers that allow the successful accomplishment of the mission goals. In the case of the 3Cat-8 mission, the most important objective is to maintain Nadir pointing during the development of the mission objectives. The Nadir pointing in the X axis is required by the camera (scientific payload) in the perpendicular axis, that has to point to the horizon during the mission. Also, the antenna communicating with the ground station is in X axis to allow communications while doing the Nadir pointing. Despite this mode being required during all the mission the controllers will have to change, as the conditions of the system will change from the original stowed CubeSat, to the configuration with the thruster activated or the antenna deployed. Additionally, to the Nadir pointing, other control modes could be required in different events. The usage of a reaction wheel, requires a de-saturation mode. In the event of low battery levels, the satellite will start Sun pointing. And finally, in the case that the thruster is not aligned with the Z axis, a mode to set the thrust vector and the speed vector in the same direction will be designed. The de-saturation mode has two aims. To prevent reaching too high or too low angular rates, and also to ensure an efficient consume of power. The reaction wheel was added to control the rotation of the Z axis. When the magnetic field is parallel to one of the axes of the magnetorquers, the rotation in that axis is impossible to achieve, and so 1 DoF is lost. Due to the polar orbit of the mission, when crossing the equator, the magnetic field will be nearly parallel to the Z axis. The reaction wheel won't be necessary out of this zone, and so the de-saturation mode will be enabled when not in use. In the case of a perfect polar Sun-synchronous orbit, Nadir pointing mode will be equivalent to Sun pointing. Expecting the Orbit to not be ideal, the Sun pointing mode will trade off a perfect Nadir pointing to achieve perpendicularity between the sunlight and the panels. This will only be needed to recharge batteries in case the power consumption is too high. The thrust vector pointing, TVP, is a mode with the aim to maximize the height raised of the orbit when the thruster is working. In the case of a thrust vector in the same direction of the velocity, this mode will act the same as the Nadir pointing. Being the thruster off center, this generates a momentum in the satellite. To minimize the momentum generated the thruster could be rotated towards the center of mass. In this case this mode will rotate the satellite, so the thrust vector is parallel again with the velocity vector. |
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Overview (resum en anglès): | |
This final degree thesis describes the development and implementation of an ADCS simulator for the 3Cat-8 mission of the UPC NanoSat Lab, which enables the calculation of the
actuators and controller variables. Additionally, based on the ADCS simulator, specially focuses on the ATHENA ionic thruster control analysis ensuring the proper ADCS actuators sizing of the spacecraft. The control is solely achieved by magnetic actuators. It is shown that the satellite can maintain the desired orientation with low angular rates, required during the orbital raising maneuver. A new configuration of the control stability with linear attitude dynamics for satellite thruster, based on a control algorithm using attitude quaternion and angular velocity feedback is also described. To conclude, the presented numerical results prove the efficiency of the applied method based on initial theoretical considerations and the design measurements of the satellite and the thruster. |