L’imagerie en profondeur in vivo à deux photons est sévèrement limitée par les aberrations optiques. L'optique adaptative est maintenant une technique largement utilisée pour résoudre ce problème. Elle repose sur une des nombreuses techniques possibles de mesure de front d'onde. L'estimation du front d'onde indirecte ou sensorless présente l'avantage d'être facile à mettre en œuvre sur les systèmes existants.L'approche modale sensorless, développée initialement pour l’imagerie à deux photons par Débarre et al., est devenue une technique standard fondée sur la maximisation d'une métrique de qualité d'image telle que l'intensité moyenne de l'image.Cependant, le front d'onde indirectement inféré est influencé par l'échantillon, qui peut induire un biais fort dans l'estimation. Cet effet est connu sous le nom de dépendance en l'échantillon.Ce travail de doctorat vise à développer une approche modale sensorless améliorée qui n'est pas affectée par la dépendance en l'échantillon. J'ai d'abord étudié l'impact des aberrations et de la structure de l'échantillon sur l'intensité moyenne de l'image.Je donne une nouvelle expression analytique de l'intensité moyenne de l'image est donnée qui rend explicite l'interaction entre la forme de la PSF 3D et la distribution spatiale de l'échantillon. À partir de simulations numériques, je montre que la sensibilité de la métrique aux aberrations est préservée pour des échantillons beaucoup plus grands que la résolution spatiale. Deuxièmement, j'étudie l'approche Standard Modal Sensorless (SMS) pour différents types d'échantillons.Je caractérise le problème de la dépendance en l'échantillon induit par des structures très fluorescentes situées hors de la profondeur de focalisation.Ensuite, je montre que la technique displacement-free n’élimine pas complètement la dépendance en l'échantillon.Cette analyse aboutit au développement de notre approche nommée Axially-Locked Modal Sensorless (ALMS). Cette nouvelle approche résout la dépendance en l'échantillon par un réglage automatique et contrôlé de la profondeur de focalisation afin de verrouiller la focalisation sur des motifs brillants de l'échantillon. En outre, l'approche ALMS se fonde également sur une métrique de qualité d'image spécialement conçue pour ce verrouillage. La performance de cette approche est numériquement comparée aux approches SMS et displacement-free. Enfin, ALMS est validée par des tests expérimentaux ex vivo et in vivo. / Deep in vivo two-photon microscopy is severely limited by optical aberrations. Adaptive optics is now a widely used technique to overcome this issue. It relies on one of several possible wavefront sensing techniques. Indirect or sensorless wavefront estimation has the advantage of being easy-to-implement on existing systems. Modal sensorless approach, initially developed for two photon imaging by Débarre et al., has become a standard technique based on the maximization of an image quality metric such as the mean image intensity.However, the indirectly inferred wavefront is influenced by the sample, which may induce a strong bias in the estimation, the so-called sample dependence. This PhD work aims at developing an improved modal sensorless approach that is not affected by sample dependence.I first study the impact of aberrations and of the sample structure on the mean image intensity.A new analytical expression of the mean image intensity is given and makes explicit the interplay between the shape of the 3D PSF and the sample spatial distribution. Through numerical simulations I show that the metric sensitivity to aberrations is preserved for samples much larger than the spatial resolution.Secondly, I study the Standard Modal Sensorless (SMS) approach for different sample scenarios. I characterize the sample dependence issue induced by strong fluorescent structures located out-of-focus. Then, I show that the displacement-free technique fails at fully removing the sample dependence. This analysis leads to the development of our Axially-Locked Modal Sensorless approach (ALMS). This new approach solves the sample dependence by an automatic and controlled adjustment of the focusing depth so as to lock on bright sample features. Furthermore, the ALMS approach is based on a specifically designed image quality metric.The performance of this approach is numerically compared with the SMS and the displacement-free approaches. Finally, ALMS is demonstrated through ex vivo and in vivo experimental tests.

Este trabalho tem por objetivo estudar e avaliar uma técnica de determinação de posição inicial de rotor em máquinas síncronas de ímã permanente de superfície. A técnica de determinação de posição inicial é baseada na aplicação de pulsos ao motor. É proposto também um algoritmo de ajuste automático desses pulsos de forma a criar um mecanismo genérico de determinação de posição inicial de ângulo de rotor para o tipo de máquina em estudo. Simulações são realizadas de forma a garantir funcionamento correto do algoritmo que foi implementado em código C com matemática de ponto fixo. A implementação foi realizada utilizando-se um microcontrolador comercial de baixo custo que não possui hardware para aritmética de ponto flutuante. Um descritivo detalhado da implementação, do sistema de testes e resultados são apresentados ao longo do texto. / This work aims the study and evaluation of a rotor initial angle estimation technique in surface mounted permanent magnet synchronous machine. The technique of the rotor initial angle estimation is based on pulse injection to the motor. It is also proposed in this work an automatic pulse adjustment algorithm in order to create a generic mechanism to estimate rotor initial angle for the machine type under study. Simulations are performed in order to ensure the proper functionality of the algorithm which was implemented in C code with fixed point mathematics. The implementation was performed using a comercial low cost microcontroller which does not have floating point arithmetic capability. A detailed description of the implementation, test system and results are presented in this text.

The development of an add-on sensorless position estimator for a 4.8 m Linear Switched Reluctance Machine (LSRM) with minimal modifications to the transducer-based controller is investigated for the first time in this study. LSRMs require position feedback for closed-loop control but present a low cost, high energy efficiency alternative for linear actuation due to their rugged construction and single-sided excitation. Mechanical position transducers mounted on the vehicle are expensive and can impact reliability. The use of a sensorless position estimator removes all electronics from the passive vehicle, resulting in considerable reductions in cost, maintenance, and mechanical complexity. This study examines the use of an add-on processor and data acquisition system for sensorless position estimation. An approach exploiting the active phase windings is used to preserve the normal operation of the transducer-based DSP controller with the goal of limiting reductions in high performance features such as force ripple reduction and velocity control [3]. The estimator system is retrofit to the transducer-based DSP controller by mimicking the output of a mechanical position sensor by emulating a Quadrature encoder. The feasibility and design issues for an add-on or retrofit position estimator are investigated. Although sensorless schemes for rotary Switched Reluctance Machines (SRMs) have been studied in detail, the problem of sensorless implementations for LSRMs has not been addressed. Experimental validation of the proposed sensorless estimation scheme is attempted, but closed-loop operation is not achieved successfully due to air gap fluctuations. In depth analysis of the sources and propagation of error is presented. / Master of Science

Master of Science / Department of Electrical and Computer Engineering / James E. DeVault / Working with the subject of sensorless motor control requires an understanding of several topical areas; this report presents an understanding that was gained during this research work. The fundamentals of electric motors (particularly brushless motors) are developed from first principles and the basic models are discussed. The theory of sinusoidal synchronous motors is reviewed (phasor analysis of the single phase equivalent circuit). The concept of a complex space vector is introduced and developed using a working knowledge of the sinusoidal synchronous motor. This leads to the presentation of the space vector model of the permanent magnet synchronous motor, in both the stationary and rotor reference frames. An overview of the operation of three-phase voltage source inverters is given, followed by an explanation of space vector modulation and its relationship to regular sinusoidal pulse width modulation. Torque control of the permanent magnet synchronous machine is reviewed in several reference frames and then rotor-flux-field-oriented-control is explained. Finally, some schemes for sensorless operation are discussed.

Saab has an analogue solution which is used to drive small motors in aircrafts. The motor is a brushless DC-motor and uses a resolver and hall sensors to control it. As sensorless control is something that has been expanding and attracting more interest over the last decade, Saab is considering the possibility of using a digital sensorless system depending on its performance on the control compared to their analogue system. There is little documentation of performance for a digital sensorless solution compared to an analogue solution. Therefore the question to be answered in this research is: How is the performance of the digital solution compared to the existing analogue solution? It was answered by finding a complete sensorless system on the market and then compare its performance to a digital system with sensors that resembles the analogue solution. Performance wise, InstaSPIN does not perform as well as EPOS2 which represent the sensorless system respective the system with sensors. InstaSPIN needs a startup sequence, can not run at the same low velocities, has a longer rise time, settling time and greater ripple. An examination of the software should be done before using the disadvantages that was found as a reason for not considering a sensorless system. Especially the startup sequence in the software should be examined as it is InstaSPINs greatest weakness compared to EPOS2. / Saab använder idag ett analogt system för att driva små motorer i deras flygfarkoster. Det analoga systemet använder en borstlös DC-motor och en resolver för styrning av motorn. Motorstyrning med system som är oberoende av givare är ett område som vuxit och fått ett ökat intresse det senaste decenniet. Saab överväger möjligheten att använda ett givarlöst digitalt system beroende på dess styrprestanda jämfört med deras analoga system. Eftersom det finns lite dokumentation om prestandan så är frågan som ska besvaras i denna rapport: Hur förhåller sig det givarlösa digitala systemet prestandamässigt jämfört med det existerande analoga systemet? Detta besvarades genom att leta upp ett komplett system på marknaden och sedan jämföra dess prestanda mot ett digitalt system som liknar det analoga systemet.  Prestandamässigt så fungerar InstaSPIN som representerar det givarlösa systemet inte lika effektivt som EPOS2 som representerar systemet som använder givare. Nackdelarna med InstaSPIN är att den behöver en startsekvens, inte kan köra på lika låga hastigheter, har längre stigtid, insvängningstid och större rippel. Man bör undersöka mjukvaran innan nackdelarna används som en anledning till att inte använda ett givarlöst system. Speciellt startsekvensen bör undersökas eftersom det är IntaSPINs största svaghet jämfört mot EPOS2.

The design and implementation of speed control driver which is applied to three-phase brushless DC fan motor are presented in this thesis. In the back-EMF detection circuit, we use digital filter circuits to obtain commutation to overcome the switch noises which are generated by high frequency PWM, without using traditional capacitor filter circuits which need more volume for additional external capacitor. Because the problems of high frequency magnetizing vibration and dispensable power consumption are generated by open-loop fixed frequency PWM speed control approach, closed-loop speed feedback control methods and closed-loop current feedback control methods are adopted to achieve high efficiency and low vibration of the fan motor drivers.

This paper proposes a sensorless control construction adapting to different speed with DSP2407 as the signal processing control core for rotation compressor. The sensorless control method obtains the rotor position by detecting the back electromotive force signals directly, then obtains better communications and the speed estimation by using digital signal which controlling power switches. Finally ,it carries out speed feedback control and current feedback control to improvt efficiency. Comparing adaptive-step control with traditional-step control and six-step control , the experiment result shows that adaptive-step control has better efficiency and lower vibration.

For energy conservation of sensorless two-phase half-wave brushless DC fan, this thesis develops a driver based on analogy circuits with current feedback control and speed feedback control. The main parts of the system include a sensorless start-up circuit, a sensorless commutation detection circuit, a speed feedback control circuit and a current feedback control circuit. Finally, we design experiments to compare it with outside PWM open-loop control and speed feedback control on experiment, the result shows that the driver with both current feedback control and speed feedback control displays better efficiency and lower vibration.

Parts orienting is an important part of automated manufacturing. Sensorless manipulation has proven to be a useful paradigm in addressing parts orienting, and the manipulation of deformable objects is a growing area of interest. Until now, these areas have remained separate because existing orienting approaches utilize forces that if applied to deformable parts violate the assumptions used by existing algorithms, and could potentially break the part. We introduce a new algorithm and manipulator actions that, when provided with the geometric description and a deformation model of choice for the part, exploits the deformation and generates a Plan that consists of the shortest sequence of manipulator actions guaranteed to orient the part up to symmetry from any unknown initial orientation and pose. Additionally, the algorithm estimates whether a given manipulator is sufficiently precise to perform the actions which guarantee the final orientation. This is dictated by the particular part geometry, deformation model, and the manipulator action path planner which contains simple end-effector constraints and any standard motion planner. We illustrate the success of the algorithm with multiple parts through 192 trials of experiments that were performed with low-precision robot manipulators and six parts made of four types of materials. The experimental trials resulted in 154 successes, which show the feasibility of deformable parts orienting. The analysis of the failures showed that for success the assumptions of zero friction are essential for this work, increased manipulator precision would be beneficial but not necessary, and a simple deformation model can be sufficient. Finally, we note that the algorithm has applications to truly sensorless manipulation of non-deformable parts.

This thesis includes two research topics. The first topic is a low-power 2-dimensional bypassing digital multiplier design. The second one is a low-power sensorless micro-controller for brushless DC motors (BLDCM). The low-power 2-dimensional bypassing digital multiplier takes advantage of a 2-dimensional bypassing method. The proposed bypassing cells constituting the multiplier skip redundant signal transitions when the horizontally partial product or the vertically operand is zero. Hence, it is a 2-dimensional bypassing architecture. Thorough post-layout simulations show that the power dissipation of the proposed 8 ¡Ñ 8 design is reduced by more than 75% compared to the prior 8 ¡Ñ 8 design with obscure cost of delay and area. The goal of the low-power sensorless micro-controller for brushless DC motors is to design a BLDCM controller without using any Hall sensor. Back-EMF estimation method using the terminal voltage sensing is adopted for the detection of the commutation moment for the proper commutation control of the BLDCM. The position of the rotor can be precisely estimated by measuring the back-EMF as well as the zero-crossing points.