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Attitude Determination and Control System for Low Earth Orbit CubeSat Considering Operation Scenario : 운영 시나리오를 고려한 저궤도 큐브위성의 자세결정 및 제어에 관한 연구

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dc.contributor.advisor기창돈-
dc.contributor.author장주영-
dc.date.accessioned2017-07-14T03:41:46Z-
dc.date.available2017-07-14T03:41:46Z-
dc.date.issued2016-08-
dc.identifier.other000000135944-
dc.identifier.urihttps://hdl.handle.net/10371/123899-
dc.description학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2016. 8. 기창돈.-
dc.description.abstractSNUGLITE (Seoul National University GNSS Laboratory satellITE), a cubesat scheduling for launch in 2017, must maintain nadir pointing attitude control in order to obtain mission data successfully and send them to ground station using S-band antenna. This thesis will examine the ADCS (Attitude Determination and Control System) algorithm and how the proposed algorithm satisfies the ADCS requirements for this particular operation scenario. The ADCS is composed of 3-axis MEMs gyroscope sensor, 2-axis coarse photodiode type sun sensors, 3-axis MEMs magnetometer, dual frequency GPS receivers, and 3-axis magnetic torquers. In the simulation environment, studies were done on the eclipse and various disturbance torques, including gravity gradient torque, solar radiation torque, and aerodynamic torque. The LQG (Linear Quadratic Gaussian) controller has been chosen for ADCS algorithm for SNUGLITE. Furthermore, this thesis will provide SILS (Simulation In the Loop System)—which takes low earth orbit environments into account—to verify the proposed ADCS algorithm. Due to the fact that the precise launch schedule of the cubesat has not yet been decided, the orbit elements have been chosen for the worst case scenario: it will provide a maximum eclipse time in altitude of 600[km] from the circular suns synchronous orbit. In order to monitor the low earth orbit environment which has a direct effect on the attitude dynamics, we developed a low earth orbit simulator that is comprised of attitude dynamics and orbit dynamics which can influence each other. We used two computers, one for the ADCS algorithm and one for the orbit environment, and transmitted data using serial communication. Thus, the team of scholars after us could use this SILS we developed to further the research on PILS (Processor In the Loop System).
The operation scenario consists of two parts. The first step starts from deployment of cubesat from P-POD (Poly Picosatellite Orbital Deployer), and detumbling using B-dot control. Second, the use of LQG controller for nadir pointing control. However, the second part of the operation scenario is also divided into two segments. In the first phase, only GPS is used as a payload but magnetic boom is not deployed, while in the second phase, magnetic boom is used for the earthquake mission.
After evaluating the simulation results, we have come to a conclusion that all the ADCS requirements were met. For instance, the attitude estimation errors were less than 5 [deg] in eclipse and less than 2 [deg] per day. In addition, the attitude control errors were less than 10 [deg] in eclipse and less than 5[deg] per day. Finally, the ADCS algorithm enabled the cubesat to turn over even in an up-side-down position.
In summary, this thesis developed and verified the ADCS algorithm which was based on the Matlab by using the LQG controller
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dc.description.abstractmoreover, it offers the space environment simulator which could be used for the PILS (Processor In the Loop System) study in the future. We expect these results will contribute to making SNUGLTIEs mission a success.-
dc.description.tableofcontentsI. Introduction 1
1. Motivation and Objectives 1
Mission for SNUGLITE 1
Necessity for ADCS (Attitude Determination and Control System) 2
Necessity for SILS (Software In the Loop System) 3
2. Previous Work 6
3. Contents and Method 10
4. Contribution 11

II. Space Environment 13
1. Modeling of Orbit 14
Sun synchronous orbit 14
Definition of coordinate framen 15
Disturbance torques 17
Earth Magnetic/Sun Model 21
2. Modeling of Cubesat 24
SNUGLITE specification 25
Attitude dynamics 26

III. ADCS Algorithm 29
1.ADCS requirements 29
2. Operation Scenario 31
3. Attitude Estimation 33
TRIAD 33
EKF 34
4. Attitude Control 43
B-dot 44
LQG 45

IV. Simulation 50
1. Simulation Configuration 50
2. Simulation Environment 52
3. Simulation Result 53

V. Conclusion 64

VI. References 65

요약 68
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dc.formatapplication/pdf-
dc.format.extent2123081 bytes-
dc.format.mediumapplication/pdf-
dc.language.isoen-
dc.publisher서울대학교 대학원-
dc.subjectSILS-
dc.subjectADCS-
dc.subjectLQG controller-
dc.subjectCube satellite-
dc.subjectLow earth orbit envrionment-
dc.subject.ddc621-
dc.titleAttitude Determination and Control System for Low Earth Orbit CubeSat Considering Operation Scenario-
dc.title.alternative운영 시나리오를 고려한 저궤도 큐브위성의 자세결정 및 제어에 관한 연구-
dc.typeThesis-
dc.contributor.AlternativeAuthorJooYoung Jang-
dc.description.degreeMaster-
dc.citation.pagesvi, 70-
dc.contributor.affiliation공과대학 기계항공공학부-
dc.date.awarded2016-08-
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