In this thesis, a combined feedforward and feedback controller for improved path tracking on autonomous heavy-duty vehicles is designed and implemented. The steering wheel is controlled in order to follow a reference curvature, computed by a higher-level MPC, responsible for minimizing the distance to a planned path. The steering dynamics, from steering wheel via wheel angles, to a measurable vehicle curvature, is modeled, and a conversion from desired curvature gain to input angle to the steering wheel is derived. Tests with an autonomous Scania R580 show that the desired curvature can be followed with satisfactory small error, both in a designed slalom path and on a more generic test track. By utilizing future curvature values computed by the MPC, a non-causal feedforward controller can reduce the delay from input to the steering wheel to a measured response in curvature, by almost two thirds, compared to the currently implemented solution. Compared to an open-loop control design, tests in simulation show that a feedback controller can reduce errors in curvature gain. However, with the identified steering dynamics and the improved conversion from steering wheel angle to curvature, no further improvement in the curvature gain was seen when implementing the feedback controller in the test vehicle. Care must also be taken not to introduce instability in the system when the feedback controller is implemented in series with a high-level MPC. / Den här rapporten beskriver design och implementering av en regulator med kombinerad framkoppling och återkoppling för förbättrad banföljning av autonoma tunga fordon. Fordonets ratt styrs för att följa en kurvaturreferens beräknad av en överordnad MPC, ansvarig för att minimera avståndet till en planerad bana. Dynamiken i styrningen, från ratten via hjulvinklarna till en mätbar kurvatur för fordonet, är modellerad. En översättning från önskad förstärkning av kurvatur till insignal för rattvinkeln är också framtagen. Tester utförda med en autonom Scania R580 visar att den önskade kurvaturen kan följas med tillfredsställande litet fel, både i en egendesignad slalombana och i en mer generisk testbana. Genom att utnyttja framtida referensvärden för kurvatur beräknade av MPC:n, kan en icke-kausal framkopplande regulator minska fördröjningen från insignal till ratten till en mätbar respons i fordonets kurvatur. Jämfört med den nuvarande lösningen minskas fördröjningen med nästan två tredjedelar. Jämfört med en öppen styrning visar tester i simulering att en återkoppling i regulatorn kan minska stationära fel i kurvatur. Med implementeringen av den identifierade styrdynamiken och den förbättrade översättningen från rattvinkel till kurvatur, syntes dock med återkoppling ingen ytterliggare förbättring i testfordonet. Implementering av den återkopplande regulatorn i serie med den överordnade MPC:n behöver också göras med omsorg för att inte introducera instabilitet i systemet.

Algebraic attacks constitute an effective class of cryptanalytic attacks which have come up recently. In algebraic attacks, the relations between the input, output and the key are expressed as a system of equations and then solved for the key. The main idea is in obtaining a system of equations which is solvable using reasonable amount of resources. The new approaches proposed in this work and experimental studies on the existing algebraic attacks on stream ciphers will be presented. In the first attack on filter generator, the input-output relations are expressed in conjunctive normal form. The system of equations is then solved using modified Zakrevskij technique. This was one of the earliest algebraic attacks on the nonlinear filter generator. In the second attack, we relaxed the constraint on algebraic attack that the entire system description be known and the output sequence extension problem where the filter function is unknown is considered. We modeled the problem as a multivariate interpolation problem and solved it. An advantage of this approach is that it can be adapted to work for noisy output sequences where as the existing algebraic attacks expect the output sequence to be error free. Adding memory to filter/combiner function increases the degree of system of equations and finding low degree equations in this case is computeintensive. The method for computing low degree relations for combiners with memory was applied to the combiner in E0 stream cipher. We found that the relation given in literature [Armknecht and Krause] was incorrect. We obtained the correct equation and verified its correctness. A time-data size trade off attack for clock controlled filter generator was developed. The time complexity and the data requirements are in between the two approaches used in literature. A recent development of algebraic attacks - the Cube attack was studied. Cube attack on variants of Trivium were proposed by Dinur and Shamir where linear equations in key bits were obtained by combining equations for output bit for same key and a set of Initialization Vectors (IVs). We investigated the effectiveness of the cube attack on Trivium. We showed that the linear equations obtained were not general and hence the attack succeeds only for some specific values of IVs. A reason for the equations not being general is given and a modification to the linear equation finding step suggested.

Music performance anxiety (MPA) is a significant concern for musicians of all ages, levels of mastery, and genders (Kenny, 2011). Whereas the anxiety-performance relationship has been well researched in athletes, similar research with musicians is sparse (Nordin-Bates, 2012). In the present research, video feed-forward self-modeling (FF-SM video) was explored as an intervention for use by musicians. FF-SM involves video-editing, typically, to depict a level of master performance higher than that yet attained by the individual. Although video FF-SM has been used successfully with athletes (Ste-Marie, Rymal, Vertes, & Martini, 2011) to increase self-efficacy and improve performance, its use has not yet been explored with musicians. In the present study, Bandura’s Self-efficacy Theory (1977) was used as a framework to explore whether FF-SM videos would increase self-efficacy, lower anxiety, and improve performance in adolescent musicians who self-reported MPA. Twelve string musicians, aged 13 to 18 years, who self-reported MPA took part in a two-week intervention where in one week they practiced with the use of a FF-SM video and in the alternate week they practiced without the video. At the end of each week, participants performed the selected repertoire from their video. Video FF-SM significantly increased musicians’ self-efficacy but only for those musicians who viewed the video in the second week. No changes in anxiety or performance levels were observed. Zimmerman’s triadic self-regulation model is used to explain the cyclical pattern of self-efficacy benefits. It is concluded that the FF-SM video can be an effective tool to increase self-efficacy for musicians who self-report MPA, but that an enactive experience is first needed for those benefits to occur. Research extended over a longer time frame is recommended in order to examine whether influences on anxiety and performance would emerge at a later time.

La prochaine génération de télescopes spatiaux devra repousser les limites des technologies actuelles afin d’accroitre les performances techniques et opérationnelles. Dans le cas d’observations difficiles, l'utilisation de plus grandes ouvertures des miroirs primaires est essentielle pour obtenir la résolution optique et la sensibilité requises. Toutefois, les grandes ouvertures primaires induisent un certain nombre de défis techniques tels que la masse, le volume et la raideur du miroir. La masse et le volume doivent rester acceptables par rapport au lanceur et la raideur du miroir, qui diminue avec l’augmentation du diamètre du miroir, doit être suffisante afin que les performances ne soient pas altérées par les déformations statiques et dynamiques. Pour surmonter ces limitations, des configurations de miroirs déformables comportant des éléments de contrôle actifs sont étudiées pour les futurs télescopes spatiaux. Les actionneurs piézoélectriques, qui répondent aux exigences de puissance massique et de bande passante, peuvent être utilisés comme éléments de contrôle actifs intégrés dans la structure de miroir. Toutefois, ces actionneurs montrent en fonctionnement en boucle ouverte des comportements non linéaires indésirables, comme le fluage et l'hystérésis, qui peuvent conduire à des inexactitudes indésirables et limiter les performances des systèmes. Par conséquent, pour les miroirs déformables activés par des actionneurs piézoélectriques, la compensation des non linéarités dans les actionneurs piézoélectriques est indispensable.La conception d’un miroir léger, compact et déformable à raideur adéquate est un défi très important pour les télescopes spatiaux mais n'est pas abordée dans cette thèse. Cette thèse porte sur le contrôle de surfaces de miroirs déformables actionnés par des actionneurs piézoélectriques et en particulier sur la compensation du fluage et de l'hystérésis dans les actionneurs piézoélectriques. La technologie de miroir actif étudié (avec des pieds activés, type miroir fakir) requiert un grand nombre d’actionneurs afin de tenir les exigences en termes de planéité de surface et ne permet pas un contrôle en boucle fermée de chaque actionneur (ce type de contrôle est trop exigeant en nombre de capteurs). La compensation du fluage et de l’hystérésis est donc réalisée en boucle ouverte et s’appuie sur des modèles précis des non linéarités à compenser et sur l’implémentation de modèles inverses. Un support d’étude expérimental a été élaboré au cours de la thèse afin de valider les études théoriques par des résultats expérimentaux. Il représente une partie d’un miroir de grande taille et consiste en une plaque de verre circulaire de diamètre 300mm dont la surface peut être actionnée par 7 actionneurs piézoélectriques annulaires.Les premières chapitres de la thèse concernent l’étude de la compensation en boucle ouverte du fluage et de l’hystérésis dans un seul actionneur qui est alors considéré comme un système SISO (single input – single output). Dans le dernier chapitre de la thèse, le fluage et de l’hystérésis sont compensés dans 3 actionneurs simultanément, ceux-ci formant un système MIMO (multi input – multi output). Les apports de la thèse concernent le développement de nouveaux modèles directs et inverses de fluage et d’hystérésis qui ont été validés par des expérimentations réalisées dans un contexte difficile de par la faible étendue des amplitudes de déplacement ( de l’ordre du micromètre). / The next generation of space-based observation systems will make use of larger primary mirrors to achieve higher image resolution. Large primary mirrors lead to the increase of structural flexibility and are more susceptible to distortions. Thus maintaining optical tolerances across the mirror surface becomes increasingly difficult. The techniques of active shape control may be required for spatial mirror surfaces in future space observation systems. Piezoelectric actuators are often studied as embedded elements for the active control of mirror structures due to their excellent properties. However, unwanted nonlinear effects in piezoelectric actuators, i.e., hysteresis and creep, severely limit the service performance. This thesis aims at developing openloopcontrol laws to compensate hysteresis and creep effects in piezoelectric actuators. The studies led during this thesis are applied to the shape control of spatial mirror surfaces. An experimental setup with a small-scale mirror test structure involving multiple piezoelectric actuators is first developed and is used as support for all the measurements conducted during this thesis. Then the open-loop control methodologies of creep compensation, hysteresis compensation, and simultaneous compensation of both the nonlinear effects in a single piezoelectric actuator are respectively developed. To compensate creep, a nonlinear viscoelastic model is used to portray creep, and a new inverse model of creep based on the concept of “voltage relaxation” is proposedRegarding the hysteresis compensation, the classical Preisach model is modified by adding a derivative term in parallel to describe hysteresis more accurately with relatively few measurements, and the new inverse model is constructed in the similar way. For the simultaneous compensation of the two nonlinear effects, the hysteresis is first compensated and then, the creepof the hysteresis-compensated piezoelectric actuator is attenuated by open-loop control. The methodology is first developed for a single actuator. Finally, the shape control of a mirror surface with several piezoelectric actuators is achieved by actuating the points on the mirror surface in such a way as to reach the required displacements. The mirror test structure involving multiplepiezoelectric actuators compensated in hysteresis and creep is considered as a linear system on which the superposition principle can be applied. The influence coefficients characterizing the coupling effect between the piezoelectric actuators are determined by measurements. The influence coefficient matrix is first constructed using the superposition principle, and is then inverted. By insertion of the inverse matrix in cascade with multiple piezoelectric actuators with hysteresis and creep compensation, a feed-forward control approach to actuate the multiple interesting points of the mirror surface is developed. A number of experimental results demonstrate that the developed control methodologies are effective and feasible in practice.

Main aim of this master’s thesis is to identify, model and control robotic manipulator with three degrees of freedom. The thesis is a part of major project [17], the aim of which is to create an educational platform. In the thesis the simple PID control and the PID with feedforward compensation control is tested on the model of simple pendulum. In the next part models of DC motors, which are used for construction of the manipulator, are developed and the inverse dynamics model of manipulator is developed. This model is used for feedforward control of the manipulator. In the final part the application was developed, which allows the manipulator to be taught some movements, which can be later on, executed. For the simple control of the application the graphical user interface was programmed.

This study investigates the impact of peripheral visual information in alleviating motion sickness when engaging in non-driving tasks in fully automated driving. A peripheral visual feedforward system (PVFS) was designed providing information about the upcoming actions of the automated car in the periphery of the occupant’s attention. It was hypothesized that after getting the information from the PVFS, the users’ situation awareness is improved while motion sickness is prevented from developing. The PVFS was also assumed not to increase mental workload nor interrupt the performance of the non-driving tasks. The study was accomplished on an actual road using a Wizard of Oz technique deploying an instrumented car that behaved like a real fully automated car. The test rides using the current setup and methodology indicated high consistency in simulating the automated driving. Results showed that with PVFS, situation awareness was enhanced and motion sickness was lessened while mental workload was unchanged. Participants also indicated high hedonistic user experience with the PVFS. While providing peripheral information showed positive results, further study such as delivering richer information and active head movement are possibly needed.

[pt] O dióxido de titânio é amplamente utilizado pela indústria e pesquisa como fotocatalisador, cuja principal desvantagem ainda é sua aplicação sob luz visível. Propriedades como quantidade de fases, tamanho do cristalito, área de superfície específica, volume de poros e valor da banda proibida (Eg) são explorados por métodos de síntes e para aprimorar a performance do TiO2. No entanto, elas são ajustadas empiracamente. O presente trabalho foi realizado a fim de descrever uma relação analítica entre essas propriedades para a fotocatálise, usando Redes Neurais Artificiais (RNAs) como ferramente estatística. Afim de ter o banco de dados mais representativo, foram usados 53 artigos. O Eg foi considerado a medida a qual avalia a performance fotocatalítica, sendo o parâmetro de saída da rede. Dois blocos A e B, distintos pelas variáveis de entrada, foram arranjados em grupos para investigar a influência das variáveis em pares, com 257 e 220 fotocatalisadores para cada, respectivamente. Exploraram-se diferentes algoritmos de treinamento (baseados em Retropropagação), tipos de redes (Feedforward, Cascade forward e Elman), funções de transferência, número de neurônios e redemulticamadas. Avaliaram-se os modelos pela Soma dos Erros Quadráticos (SSE),pelo coeficiente de correlação de regressão (R2) tanto para o treinamento e quanto para o teste, pelo comportamento de predição do banco de dados e pelo diagrama de regressão dos valores preditos pelos observados. Os resultados do bloco A sugerem que as variáveis não aparentam ter uma relação. Os modelos de múltiplas camadas no bloco B revelaram um aumento no desempenho. O resultado de maior coeficiente teve topologia de 4-4-6-1, correspondendo a camada de entrada, primeira camada oculta, segunda camada oculta e camda de saída, respectivamente. Obteve-se R2 de 84 por cento para o treinamento e 50 por cento para o teste, com SSE de 2.24.Esse resultado sugere que a rede não é capaz de prever o Eg, mas ela pode ser aprimorada. Os parâmetros estruturais devem ser revisados, de acordo com padrões de caracterizações e dados estatísticos. Consequentemente, o modelo pode ser bem ajustado, otimizado e usado na melhoria da fotocatálise. / [en] Titanium dioxide has been widely applied by industry and scientific research as a photocatalyst,whose main drawback still has been the application under visible light.Properties such as phases amount,crystallite size, specific surface area, pore volume, and band gap value (Eg)have been explored by synthesis methods to improve TiO2 s performance. However, they are empirically adjusted.The present work was carried out to describe an analytical relation between those properties for photocatalysis, using Artificial Neural Networks (ANNs) as a statistical tool. Aiming the most representative set, 53 literature papers were used for the database. Eg was considered the measurement which evaluates the photocatalytic performance, namely the network s out put variable. Two blocks A and B, which are distinguished by input variables, were arranged into groups to investigate the variables pair influences, using 257 and 220 photocatalysts vectors for each,respectively. Modelling attempts examined different training algorithms(based on Back- propagation), types of networks (Feedforward, Cascade forward and Elman), transfer functions, number of hidden neurons, and multilayer network.The developedmodelswereevaluatedbythesumofsquarederror(SSE),the correlation coefficient(R2) of regression for both training and test data, the prediction behaviour of the dataset,and the regression diagram of predicted and observed values. The block A results suggest the variables do not have an apparent relationship. Multilayers models on block B revealed an increase of network identification performance. The result with the highest coefficient showed 4-4-6-1 topology; corresponding, respectively, to input, first hidden, second hidden and output layers.It had R2 of 84 percent for training and to 50 percent fortest, with SSE of 2.24.This result suggests this network is not able topredict the Eg, but it can be improved. The structural properties should be reviewed, according to standards of characterization and statistical data. Hence, the model could be well fitted, optimized, and used for photocatalysis improvement.

I denna rapport utreds olika metoder för att kunna reglera vattennivån i vattenkraftverket Avesta Lillfors i Dalarna. Två kraftverk ligger endast 900 m uppströms och detta gör att svarstiderna blir korta och regleringen blir lätt nervös. Att använda sig av vattennivåreglering i ett kraftverk för-enklar dess styrning då anpassning till inflödet sker automatiskt. En flödestabell har tagits fram genom mätningar i turbinen, med hjälp av Winter-Kennedy-metoden. Denna tabell används för att kunna fram-koppla regulatorn och därmed dämpa stora variationer i inflödet. Dessu-tom har en modell av älven skapats och testats med en återkopplad PID-regulator. Utefter dessa tester har lämpliga parametrar tagits fram, som ger önskad stabilitet, noggrannhet och snabbhet. Simuleringar har även gjorts med reglermetoden Fuzzy logic. / This report evaluates different methods to create a stable regulation of the water level in the hydro power plant Avesta Lillfors, in county Dalar-na. Another pair of plants are located just 900 m up the stream, which is why the regulation has to act fast. If the water level can be regulated and automatically adjust to the incoming flow, it facilitates the control of the plant. A flow chart is created from measurements in the turbine, using the Win-ter-Kennedy method. The results are used for feedforward control. A PID-regulator with feedback is also simulated in a model of the river. This helps finding the parameters that provide a stable, accurate and fast regu-lation. Fuzzy logic control has also been simulated.

An active noise control (ANC) system has been applied to the problem of attenuating low-frequency tonal noise inside small enclosures. The intended target application of the system was the reduction of the engine firing frequency inside heavy equipment cabins. The ANC system was based on a version of the filtered-x LMS adaptive algorithm, modified for the minimization of acoustic energy density (ED), rather than the more traditional minimization of squared acoustic pressure (SP). Three loudspeakers produced control signals within a mock cabin composed of a steel frame with plywood sides and a Plexiglas® front. An energy density sensor, capable of measuring acoustic pressure as well as acoustic particle velocity, provided the error signal to the control system. The ANC system operated on a single reference signal, which, for experiments involving recorded tractor engine noise, was derived from the engine's tachometer signal. For the low frequencies at which engine firing occurs, experiments showed that ANC systems minimizing ED and SP both provided significant attenuation of the tonal noise near the operator's head and globally throughout the small cabin. The tendency was for ED control to provide a more spatially uniform amount of reduction than SP control, especially at the higher frequencies investigated (up to 200 Hz). In dynamic measurement conditions, with a reference signal swept in frequency, the ED control often provided superior results, struggling less at frequencies for which the error sensor was near nodal regions for acoustic pressure. A single control channel often yielded performance comparable to that of two control channels, and sometimes produced superior results in dynamic tests. Tonal attenuation achieved by the ANC system was generally in excess of 20 dB and reduction in equivalent sound level for dynamic tonal noise often exceeded 4 dB at the error sensor. It was shown that temperature changes likely to be encountered in practice have little effect on the initial delay through the secondary control path, and are therefore unlikely to significantly impact ANC system stability in the event that a fixed set of system identification filter coefficients are employed.

Visual cues have previously been classified as visual exproprioceptive, when defining the relative position of the body within the environment and are continuously updated while moving (online), and visual exteroceptive when describing static features of the environment which are typically elaborated offline (feedforward). However peripheral visual cues involved in the control of movement have not previously been clearly defined using this classification. Hence the role played by peripheral visual cues in the planning and/or online control of movement remains unclear. The aim of this thesis was to provide a systematic understanding of the importance of peripheral visual cues in several types of movement, namely overground locomotion, adaptive gait, postural stability and reaching and grasping. 3D motion capture techniques were used to collect limb and whole body kinematics during such movements. Visual peripheral cues were manipulated by visual field occlusion conditions or by the employment of point-lights in a dark room. Results showed that the visual cues provided by different parts of the peripheral visual field are mainly used for online fine tuning of limb trajectory towards a target (either a floor-based obstacle or an object to grasp). The absence of peripheral visual cues while moving disrupted the spatio-temporal dynamic relationship between subject and target and resulted in increased margins of safety between body and target and increased time and variability of several dependent measures. These findings argue in favour of the classification of peripheral visual cues as visual exproprioceptive.