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Modeling, Estimation and Attitude Control of an Octorotor Using PID and L1 Adaptive Control Techniques / Modellering, estimering och attitydreglering av en oktakopter med användning av PID- och L1-adaptiv teknikBergman, Kristoffer, Ekström, Jonatan January 2014 (has links)
A multirotor is a type of aerial vehicle that has attracted a lot of attention in recent years. Multirotors have found applications in a variety of different fields and they are used by scientists and researchers, commercial UAV companies and radio control enthusiasts alike. In this thesis a multirotor with eight rotors, also called an octorotor, is used. A physical model of the octorotor has been developed using theory from rigid body mechanics and aerodynamics. The unknown parameters in this model have been found using several identification experiments. The model has been used for controller design and comparison in a simulation environment. An attitude estimation algorithm has been designed and implemented on the target hardware. The algorithm is referred to as a nonlinear complementary filter and it uses a quaternion rotation representation and onboard measurements to compute an estimate of the current aircraft attitude. Two different attitude controllers have been designed and evaluated. The first controller is based on PID techniques which are commonly used in multirotor flight stabilization systems. The second controller uses a novel control structure based on L1 adaptive control techniques. A baseline attitude PD controller is augmented with an L1 adaptive controller in the rate feedback loop. The two controller structures are compared using a simulation environment based on the developed model of the octorotor. The results show that the proposed structure gives a notable performance increase with respect to robustness against modeling errors and input disturbance rejection compared to the PID controller. However, the L1 adaptive controller is more complex to implement and gives less noise attenuation. The PID controller has been implemented on the platform's hardware and initial flight tests have been performed with promising results. / En multirotor är en typ av flygande farkost som har fått mycket uppmärksamhet under senare år. Multirotorer tillämpas inom flertalet områden och de används av bland annat forskare och vetenskapsmän, kommersiella UAV- företag samt hobbyentusiaster. I detta examensarbete används en multirotor med åtta rotorer, en så kallad oktakopter. En fysikalisk modell av oktakoptern har tagits fram med hjälp av teori från stelkroppsmekanik och aerodynamik. De okända parametrarna i modellen har skattats med hjälp av ett flertal identifieringsexperiment. Modellen har använts för att designa och jämföra regulatorer i en simuleringsmiljö. En algoritm för att skatta farkostens attityd har designats och implementerats på oktakopterns hårdvara. Algoritmen är en variant av ett olinjärt komplementärt filter och använder en kvaternionrepresentation av attitydvinklar och uppmätt sensordata för att skatta farkostens nuvarande attityd. Två olika attitydregulatorer har designats och utvärderats. Den första regulatorn är baserad på PID-teknik vilket är vanligt för stabilisering av multirotorsystem. Den andra regulatorn använder en ny regulatorstruktur baserad på L1-adaptiv teknik. En grundregulator av PD-typ utökas med en L1-adaptiv regulator i vinkelhastighetsloopen. De två regulatorstrukturerna jämförs i en simuleringsmiljö baserad på den framtagna modellen av oktakoptern. Resultaten visar att den föreslagna regulatorstrukturen ger en betydande prestandaökning gällande robusthet mot modellfel och undertryckning av ingångsstörningar jämfört med PID-regulatorn. Dock är L1-regulatorn mer komplex att implementera och den ger mindre brusundertryckning. PID-regulatorn har implementerats på plattformens hårdvara och inledande flygtester har genomförts med lovande resultat.
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Feasibility study of a moon sensor for satellite attitude determinationSkinner, Robert Edmid 12 1900 (has links)
Thesis (MScEng)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: The purpose of this study was to investigate the feasibility of a moon sensor as an alternative
or supplemental sensor to supply attitude information to a satellite. The visibility of the moon
was evaluated with regards to that of the sun from a satellite (i.e. the feasibility of the moon
sensor is compared to that of a sun sensor).
An algorithm was developed to calculate the center of the moon, regardless of phase or
rotation, to offer increased accuracy of the center of the moon. The accuracy of this
algorithm and the possible error margins were evaluated and discussed in both ideal and
actual test cases. The sensor was implemented on embedded hardware.
The conclusion of the feasibility analysis was that the sensor would function well as a
supplemental sensor (e.g. in conjunction with a sun-sensor) rather than as an alternative
sensor. The accuracy of the moon center algorithm was satisfactory for attitude
deterrnina tion.
This sensor could thus be seriously considered for use on a future satellite. / AFRIKAANSE OPSOMMING: Die doel van die studie is om die lewensvatbaarheid van 'n maan-sensor, as alternatiewe of
aanvullende sensor, om oriëntasie data aan 'n sateliet te verskaf, te ondersoek. Die sigbaarheid
van die maan en die sigbaarheid van die son is met mekaar vergelyk, vanaf 'n sateliet (m.a.w.
die uitvoerbaarheid van 'n maan-sensor is vergelyk met dié van 'n son sensor).
'n Algorittne is ontwikkel om die middelpunt van die maan, ongeag van fase of rotasie,
te bereken om verhoogde akuraatheid van die maan se middelpunt te bied. Die akuraatheid
van die maan-middelpunt algoritme en moontlike foute is evalueer en bespreek in beide ideale
sowel as werklike toets gevalle. Die sensor was op hardeware geimplenteer.
Die gevolgtrekking van die lewensvatbaarheids analise is dat die sensor effektief sal
funksioneer as 'n aanvullende sensor (d.w.s saam met 'n son sensor) eerder as 'n alternatiewe
sensor. Die resultate verkry van die evaluasie van die maan-middelpunt algoritme is
bevredegind en is voldoende vir oriëntasie bepaling.
Die sensor kan dus ernstig oorweeg word vir gebruik op 'n sateliet in die toekoms.
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Development of a fault-tolerant bus system suitable for a high-performance, embedded, real-time application on SUNSAT's ADCSFarr, Xandri C. 12 1900 (has links)
Thesis (MEng)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: The Attitude Determination and Control System (ADCS) of the Stellenbosch University
Satellite (SUNSAT I) is an integrated system providing some redundancy and the necessary
data management to control the spacecraft. However, the redundancy is not easily
accessible and there is a lack in flexibility when testing individual modules during integration
or when the system needs to be extended. The objective of this thesis was thus
to develop a high reliability, flexible, modular communication system that included some
type of redundancy to manage real-time data and to prevent severe malfunctioning of the
entire system.
The first step in the project's development methodology was to summarise the requirements
and specifications by studying the current ADCS architecture and data management.
An investigation into the Controller Area Network (CAN) protocol showed that
this technology would fit the requirements very well, leading to the design and implementation
of several concept topologies based on CAN. Thereafter, a demonstration model
consisting of three prototype nodes was composed. The performance of the so called
dual CAN node was analysed and an extrapolation was 'made to determine whether the
architecture could support the complete ADCS.
It was demonstrated that the dual CAN node provides enough room to accommodate
all the processors, actuators and sensors of the ADCS. At the same time, it was shown
that reliability and robustness was increased by enhanced redundancy at a node-level as
well as at the greater system-level. A dual CAN bus was provided for redundancy at
a node-level. At the system-level, the command and data-gathering modules (ACP or
OBC's) can now effectively be multiplexed on the network of actuators and sensors. Furthermore,
it was shown that error detection capabilities and diagnostics can be enhanced
and the complexity of the communication architecture and related wiring harnesses can
be reduced. This allows easier access to modules and simplifies development. / AFRIKAANSE OPSOMMING: Die Attitude Determination and Control System (ADCS) van Stellenbosch University
Satellite (SUNSAT I) is 'n geïntegreerde stelsel wat voorsiening maak vir 'n mate van
oortolligheid en 'n vermoeë om stelseldata te bestuur vir goeie satellietbeheer. Nietemin,
hierdie oortolligheid is nie baie toeganklik nie en daar is 'n gebrek aan aanpasbaarheid
tydens die toets en integrasie van individuele modules of moontlike stelseluitbreidings.
Die doelwit van hierdie tesis was dus die ontwikkeling van 'n betroubare, aanpasbare,
modulêre kommunikasie stelsel wat 'n tipe oortolligheid insluit sodat intydse data bestuur
kan word en algehele stelselondergang vermy kan word.
Die eerste stap in die projek se ontwikkelings metodiek was om 'n opsomming te verkry
van die vereistes en spesifikasies deur die huidige ADCS se argitektuur en databestuur
te ondersoek. 'n Ondersoek na die Controller Area Network (CAN) protokol het getoon
dat hierdie tegnologie aan baie van die vereistes voldoen. Dit het aanleiding gegee tot die
ontwerp en implementering van 'n paar konsep ontwerpe gebaseer op CAN. Daarna is 'n
demonstrasie model bestaande uit drie prototipe nodusse gebou. Die werksverrigting van
die sogenoemde dual CAN node, is ondersoek en 'n ekstrapolasie was gemaak om vas te
stelof die argitektuur die volkome ADCS kan huisves.
Deur demonstrasie was daar getoon dat die dual CAN node wel genoeg ruimte verskaf om
al die verwerkers, aktueerders en sensors van die ADCS te akkommodeer. Daar was terselfdertyd
getoon dat betroubaarheid en robuustheid verhoog is deur die verbeterde oortolligheid
op 'n node-vlak sowel as op die groter stelsel-vlak. 'n Dubbele CAN bus is gebruik
vir oortolligheid op 'n node-vlak. Op 'n stelsel-vlak kan die bevel-en-dataversamelings
modules (ACP en aBC's) effektief gemultipleks word op die netwerk van aktueerders
en sensors. Daar was verder getoon dat die foutopspoorings vermoeë en diagnostiese
vermoeë verbeter kan word en die kompleksiteit van die kommunikasie argitektuur en
ooreenkomstige kabelharnasse vereenvoudig kan word. Die gevolg is vereenvoudigde toegang
tot modules en vergemaklikde opgradering.
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Attitude sensor and actuator interfacing for micro-satellitesDlamini, Zamokwakhe P. (Zamokwakhe Peacemaker) 12 1900 (has links)
Thesis (MScEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The purpose of this thesis was to design and test the interfaces of sensors and actuators. In the
complete Attitude Determination and Control System CADCS) the Interface Control Processor
(ICP) must be interfaced to various sensors and torquers.
The testing of interfaces involves the simulation of sensors and actuators and also two of the
Attitude Control Processor's functions, i.e. sending actuator commands and receiving sensor
data. The tested interfaces are for two actuators and three sensors. Both analog and digital
sensors and actuators are interfaced i.e. reaction wheels, magnetorquers, magnetometer and
horizon /fine sun sensor. The simulated sensors and actuators are to be employed on three axis
controlled, low earth o~biting micro-satellites.
To test the interfaces, a test circuit was developed and the design is presented. Finally the
software to facilitate the testing was developed and is also presented with the analysis based on
protocol implementation and data rates. / AFRIKAANSE OPSOMMING: Die doel van hierdie tesis was om sensor en aktueerder koppelvlakke te ontwerp en te toets. In
die volledige Attitude Determination and Control System CADCS) moet die Interface Control
Processor CICP) aan verskeie sensore en torquers gekoppel word.
Die toets van koppelvlakke behels die simulasie van sensore en aktueerders en ook twee van die
Attitude Control Processor (ACP) se funksies, naamlik die stuur van aktueerder bevele en die
ontvang van sensor data. Die koppelvlakke vir twee aktueerders en drie sen sore is getoets.
Beide analoog en digitale sensore en aktueerders is gekoppel, naamlik die reaksiewiele,
magneetspoele, magnetometer en horison I fyn son sensor. Die gesimuleerde sensore en
aktueerders sal gebruik word op drie-as beheerde, lae aardbaan mikrosatelliete.
Om die koppelvlakke te toets is 'n stroombaan ontwikkel waarvan die ontwerp hier aangebied
word. Sagteware om die toetse te fasiliteer is ontwikkel en word ook hier aangebied tesame met .
analises gebaseer op protokol implementering en data tempo's.
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Integrated attitude determination system using a combination of magnetometer and horizon sensor dataMaass, E. (Eanette) 12 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: A different approach of employing attitude sensors with incomplete measurements
in an attitude determination system is investigated. The amount of available attitude
sensors on small satellites are limited, and the failure of sensors can be fatal
when accurate attitude determination is necessary. The problem with sensors
with incomplete measurements is that they must be used in combination with
other sensors to obtain three dimensional attitude information. The aim is to
enhance the possible number of sensor combinations that can be employed, in an
attempt to improve the ability of the attitude determination system to tolerate
sensor failures.
An alternative sensor structure consisting of a magnetometer and two horizon
sensors is presented. A method to obtain vector observations of the attitude
from a combination between magnetometer and horizon sensor measurements is
derived and tested. A full state Extended Kalman Filter is used to determine
the satellite's attitude, attitude rate and disturbance torque from these vector
observations.
A second Extended Kalman Filter structure, using only magnetometer measurements,
is implemented. The magnetometer Extended Kalman Filter and the
horizon/magnetometer Extended Kalman Filter are integrated to obtain a single
Extended Kalman Filter structure to determine the satellite's full attitude state.
Integration is done by switching between the different pairs of vector information.
A systematic analysis of the integrated filter's dynamic behaviour during
the switching stages is done by means of a series of case studies. / AFRIKAANSE OPSOMMING: Die gebruik van oriëntasiesensore met onvolledige metingsdata in oriëntasiebepalingsstelsels
is ondersoek. Slegs 'n beperkte aantal oriëntasiesensore is beskikbaar
op mikro satelliete. 'n Foutiewe sensor kan dus noodlottig wees wanneer akkurate
oriëntasiebepaling nodig is. Die probleem met sensore met onvolledige metingsdata
is dat dit in sensor kombinasies gebruik moet word om drie dimensionele
oriëntasieinligting te verkry. Die doel is dus om die moontlike aantal sensor kombinasies
sodanig te vermeerder dat die oriëntasiebepalingsstelsel beter bestand
sal wees teen moontlike sensor falings.
'n Alternatiewe sensor struktuur, bestaande uit 'n magnetometer en twee horison
sensore, is ondersoek. 'n Metode vir die verkryging van 3-as oriëntasie inligting
vanaf 'n kombinasie van magnetometer en horison sensor metingsdata is afgelei
en getoets. 'n Vol toestand uitgebreide Kalmanfilter is gebruik om the satelliet
se oriëntasie, oriëntasie snelheid en versteurings draairnoment vanaf die vektor
observasies af te lei.
'n Tweede uitgebreide Kalmanfilter struktuur, wat slegs magnetometer metingsdata
gebruik, is geïmplementeer. Die magnetometer filter en die horison/magnetometer
filter is geïntegreer sodat een uitgebreide Kalmanfilter struktuur volle
oriëntasie inligting kan aflei vanaf verskillende pare vektors met oriëntasie inligting.
Integrasie is gedoen deur te skakel tussen die verskillende vektorpare. 'n
Sistematiese analise van die geïntegreerde filter se dinamiese gedrag gedurende
die oorskakelingstye is gedoen deur middel van 'n reeks gevallestudies.
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Contributions à l'estimation et à la commande d'attitude de véhicules aériens autonomes / Attitude estimation & control of autonomous aerial vehiclesBenziane, Lotfi 15 June 2015 (has links)
Les drones ou systèmes de drones aériens jouent un rôle de plus en plus important danstous les domaines, spécialement les drones à décollage et atterrissage verticaux. L’un desplus connus est le Quadrotor et, sans doute, il est la plateforme de recherche la plus utilisée.Cette thèse traite le problème de l’estimation et de la commande d’attitude appliqué àun corps rigide se déplaçant dans l’espace 3D tel que le Quadrotor. La première contributionde cette thèse est la conception et l’implémentation d’une solution d’estimation d’attitude.Celle-ci est basée sur un ensemble de filtres complémentaires combinés avec un algorithmealgébrique tel que TRIAD, QUEST, etc. avec la possibilité de choisir deux formes différentesdes filtres: la première dénommée forme Directe, et la seconde dénommée forme Passive.Les filtres proposés ont une flexibilité dans le choix de l’ordre qui peut être pris grand afinde bien réduire l’effet du bruit de mesure et permettent d’aboutir à un estimateur qui peutprendre en compte le biais éventuel des gyromètres. L’analyse par la théorie de Lyapunovprouve que les erreurs d’estimation tendent globalement et asymptotiquement vers zéro. Unesuite logique de cette première contribution est la proposition d’une solution pour la commanded’attitude qui constitue la deuxième contribution de cette thèse. Elle se traduit par ledéveloppement d’une nouvelle loi de commande d’attitude d’un corps rigide dans l’espace3D, dans laquelle seulement les vecteurs de mesures inertiels avec les mesures des gyromètressont utilisés. Elle utilise le principe de fusion des données à travers un filtre complémentairepermettant l’élimination des bruits des mesures tout en assurant une stabilité presque globalede l’équilibre désiré. La troisième contribution est une loi de commande pour la stabilisationd’attitude sans mesure de vitesse angulaire, ni mesure d’attitude. Pour cela, un systèmelinéaire auxiliaire basé sur les mesures des vecteurs inertiels a été introduit. Ce dernier sesubstitue au manque de l’information de la vitesse angulaire. L’analyse de stabilité du contrôleurproposé est basée sur la théorie de Lyapunov couplée avec le théorème de LaSalle. Ellepermet de conclure sur la stabilité presque globale de l’équilibre désiré. Les performances dessolutions proposées ont été validées par un ensemble de tests expérimentaux / Nowadays, we see a growing popularity of the use of Unmanned Aerial Vehicles (UAV) ofespecially Vertical Take-Off and Landing (VTOL) type. One of the most known VTOL is thequadrotor or Quadcopter which is probably the most used one as a research platform. Thisthesis deal with attitude control and estimation techniques applied to a rigid body movingin 3D space such as Quadcopter VTOL. The first contribution of this thesis is the design ofa new class of complementary linear-like filters allowing the fusion of inertial vector measurementswith angular velocity measurements and combined with algebraic algorithms asTRIAD, QUEST etc. to give an efficient attitude estimation solution. This class of filtersallows several possibilities of implementation such as the order of the filters which can bechosen high in order to reduce more the measurement noise and the form of the filters thatcan be direct or passive and the ability to take into account the possible gyro bias. Lyapunovanalysis shows the global asymptotic convergence of the estimation errors to zero. The sameprinciple of data fusion is used for the proposed new attitude control law in which the complementaryfilters were included to reduce the effect of measurement noise. The obtainedcontroller ensures almost global stability of the desired equilibrium point; it represents thesecond contribution of this thesis. The third contribution takes into consideration an interestingspecial case, where instantaneous measurements of attitude and angular velocity areunavailable. A first order linear auxiliary system based directly on vector measurements isused in an observer-like system to handle the luck of angular velocity. The proposed controllerensures almost global asymptotic stability of the trajectories to the desired equilibriumpoint. Detailed sets of experiments were done to validate the obtained results
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Optimal regulation within spatial constraints : an application to flexible structuresTaylor, Edward Gregory January 1980 (has links)
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO. / Includes bibliographical references. / by Edward Gregory Taylor. / Ph.D.
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Genetic Fuzzy Attitude State Trajectory Optimization for a 3U CubeSatWalker, Alex R. 22 October 2020 (has links)
No description available.
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Development of Tailsitter Hover Estimation and ControlBeach, Jason M. 11 February 2014 (has links) (PDF)
UAVs have become an essential tool in many market segments, particularly the military where critical intelligence can be gathered by them. A tailsitter aircraft is a platform whose purpose is to efficiently merge the range and endurance of fixed-wing aircraft with the VTOL capabilities of rotorcraft and is of significant value in applications where launch and recovery area is limited or the use of launch and recovery equipment is not desirable. Developing autopilot software for a tailsitter UAV is unique in that the aircraft must be autonomously controlled over a much wider range of attitudes than conventional UAVs. Assumptions made in conventional estimation and control algorithms are not valid for tailsitter aircraft because of routine operation around gimbal lock. Quaternions are generally employed to overcome the limitations Euler angles; however, adapting the attitude representation to work at a full range of attitudes is only part of the solution. Kalman filter measurement updates and control algorithms must also work at any orientation. This research presents several methods of incorporating a magnetometer measurement into an extended Kalman filter. One method combines magnetometer and accelerometer sensor data using the solution to Wahba's problem to calculate an overall attitude measurement. Other methods correct only heading error and include using two sets of Euler angles to update the estimate, using quaternions to determine heading error and Euler angles to update the estimate, and using only quaternions to update the estimate. Quaternion feedback attitude control is widely used in tailsitter aircraft. This research also shows that in spite of its effective use in spacecraft, using the attitude error calculated via quaternions to drive flight control surfaces may not be optimal for tailsitters. It is shown that during hover when heading error is present, quaternion feedback can cause undesired behavior, particularly when the heading error is large. An alternative method for calculating attitude error called resolved tilt-twist is validated, improved, and shown to perform better than quaternion feedback. Algorithms are implemented on a commercially available autopilot and validation is performed using hardware in loop simulation. A custom interface is used to receive autopilot commands and send the autopilot simulated sensor information. The final topic covered deals with the tailsitter hovering in wind. As the tailsitter hovers, wind can cause the tailsitter to turn such that the wind is perpendicular to the wings. Wind tunnel data is taken and analyzed to explain this behavior.
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Low-Cost Reaction Wheel Design for CubeSat ApplicationsBonafede, Nicholas J, Jr. 01 August 2020 (has links) (PDF)
As science instruments on CubeSats become more sensitive to the attitude of the spacecraft, better methods must be employed to provide the accuracy needed to complete the planned mission. While systems that provide the accuracy required are available commercially, these solutions are not cost-effective, do not allow the design to be tailored to a specific mission, and most importantly, do not give students hand-on experience with attitude control actuators. This thesis documents the design, modeling, and simulation of a low-cost, student-fabricated, reaction wheel system for use in 3U CubeSat satellites. The entire design process for the development of this reaction wheel is based on fundamental design principles and can be replicated for either larger or smaller spacecraft as needed. Additionally, plans for bringing this design up to a prototyping and testing phase are outlined for continued use of this design in the Cal Poly CubeSat Laboratory.
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