Fault tolerant attitude control for nanosatellites: ESTCube-2 case
Date
2024-01-23
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Abstract
Käesolev uurimus viidi läbi Tartu Ülikoolis, Tartu Observatooriumis, Soome meteoroloogiainstituudis ja Eesti Tudengisatelliidi programmis. See töö käsitleb ESTCube-2 asendi määramise ja kontrolli süsteemi (ADCS). ESTCube-2 on kolmeühikuline kuupsatelliit. ESTCube-2 missiooni peamine teaduslik eesmärk on katsetada orbiidil elektrilist päikesepurje. Elektriline päikesepuri on kütusevaba tõukesüsteemi kontseptsioon. ESTCube-2 proovib demonstreerida uusi tehnoloogiad, mis võimaldaks planeerida süvakosmose missioone kuup- ja nanosatelliitidele. See töö keskendub veakindla kontrollsüsteemi arendamisele ESTCube-2 satelliidi jaoks, mille eesmärgiks on testida plasmapidurit maa-lähedasel orbiidil (LEO). Missiooni õnnestumiseks on asendi määramise ja kontrolli süsteemil kindlad nõuded, mille hulgas on lõõa välja laskmine ja pöördemomendi täpsuse ja stabiilsuse kontroll vastavalt 0.25 kraadi ja 0.125 kraadi/s täpsusega. Antud uurimuse eesmärk on luua veakindel süsteem (FTC), mis käsitleb vigu ja ebakorrapärasusi ilma vajaduseta neid tuvastada, vähendades süsteemi arvutuslikku keerukust. Selleks on välja pakutud integreeritud anti-windup (AW) tõrkekindel juhtsüsteem. See süsteem hõlmab anti-windup kompensaatori disaini, mis käsitleb täiturite küllastumist. Käsitletakse kahte lahendust: mitme-sisendi/mitme-väljundiga (MIMO) ja ühe-sisendi/ühe- väljundiga (SISO) või ühe-sisendi/mitme-väljundiga (SIMO) AW kompensaatorit. Iga üksiku kontrollkanali puhul kaalutakse SISO/SIMO lähenemisviisi, mis tagab läbipaistvuse ja paindlikkuse sõltumatu kanali kavandamisel ja häälestamisel. AW-kompensaatori jõudlus on paljutõotav, vähendades arvutuskoormust ja lihtsustades kanali häälestamist. Töös pakutakse välja ka selle arhitektuuri kombinatsioon adaptiivse Neuro-Fuzzy Inference System (ANFIS) kontrolleriga, mis pakub sujuvamaid kontrollreaktsioone rikete korral.
This research was carried out at the University of Tartu, Tartu Observatory, the Finnish Meteorological Institute and the Estonian Student Satellite Programme. This thesis presents the ESTCube-2 attitude determination and control system (ADCS). ESTCube-2 is a satellite built according to the three-unit CubeSat standard. The main scientific mission of ESTCube-2 is to perform the in-orbit electric solar wind sail demonstration. The electric solar wind sail is a propellant-less propulsion technology concept. Ultimately, the ESTCube-2 nanosatellite will aim to demonstrate technologies for deep interplanetary space mission of CubeSats and nanosatellites. This thesis focuses on designing a fault-tolerant control architecture for the ESTCube-2 nanosatellite, which is tasked with demonstrating plasma brake technology in Low Earth Orbit (LEO). The satellite has specific requirements for its ADCS to achieve its mission objectives, including tether deployment and angular momentum control with pointing accuracy and pointing stability of 0.25 deg and 0.125 deg /s respectively. The research aims to provide a fault-tolerant control (FTC) architecture that can handle faults and disturbances without the need to identify the faults, thus reducing computational complexity. An integrated anti-windup fault-tolerant control architecture is proposed. This includes the design of an anti-windup (AW) compensator, which addresses actuator saturation. Two design approaches are discussed: a full-order multi-input multi-output (MIMO) AW compensator and single-input/single-output (SISO) or single-input/multi- output (SIMO) designs. The SISO/SIMO approach is considered for each individual control channel, providing transparency and flexibility for independent channel design and tuning. The AW compensator’s performance is found to be promising, reducing computational burden and simplifying channel tuning. The thesis also proposes a combination of this architecture with an Adaptive Neuro-Fuzzy Inference System (ANFIS) controller, which offers smoother control reactions in the presence of faults.
This research was carried out at the University of Tartu, Tartu Observatory, the Finnish Meteorological Institute and the Estonian Student Satellite Programme. This thesis presents the ESTCube-2 attitude determination and control system (ADCS). ESTCube-2 is a satellite built according to the three-unit CubeSat standard. The main scientific mission of ESTCube-2 is to perform the in-orbit electric solar wind sail demonstration. The electric solar wind sail is a propellant-less propulsion technology concept. Ultimately, the ESTCube-2 nanosatellite will aim to demonstrate technologies for deep interplanetary space mission of CubeSats and nanosatellites. This thesis focuses on designing a fault-tolerant control architecture for the ESTCube-2 nanosatellite, which is tasked with demonstrating plasma brake technology in Low Earth Orbit (LEO). The satellite has specific requirements for its ADCS to achieve its mission objectives, including tether deployment and angular momentum control with pointing accuracy and pointing stability of 0.25 deg and 0.125 deg /s respectively. The research aims to provide a fault-tolerant control (FTC) architecture that can handle faults and disturbances without the need to identify the faults, thus reducing computational complexity. An integrated anti-windup fault-tolerant control architecture is proposed. This includes the design of an anti-windup (AW) compensator, which addresses actuator saturation. Two design approaches are discussed: a full-order multi-input multi-output (MIMO) AW compensator and single-input/single-output (SISO) or single-input/multi- output (SIMO) designs. The SISO/SIMO approach is considered for each individual control channel, providing transparency and flexibility for independent channel design and tuning. The AW compensator’s performance is found to be promising, reducing computational burden and simplifying channel tuning. The thesis also proposes a combination of this architecture with an Adaptive Neuro-Fuzzy Inference System (ANFIS) controller, which offers smoother control reactions in the presence of faults.
Description
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Keywords
ESTCube-2, satelliidid (tehnika), asendimääramise süsteem, artificial satellites, attitude determination system