Title page, abstract and table of contents only. The complete thesis in print form is available from the University of Adelaide Library. / Compact, lightweight and responsive direct current (DC) motors are desirable in industries requiring precise control operations such as those using robotic and micro-robotic devices. Permanent magnet (PM) motors have been used exclusively in these industries, in recent years, because they meet these requirements. However, their speed range and output torque are limited compared to wound field direct current (WF DC) motors and this renders them far less effective than WF DC motors in terms of handling load disturbances. So far, only one study by Reyer and Papalambros (1999) has investigated a method for concurrently optimising the weight and response of WF DC motors with, in this case, proportional, integral and derivative (PID) controllers. However, the documentation provided in their study suggests that their optimised WF motor was defective in terms of efficiency, speed and shape. The aim of the present study was to develop Reyer and Papalambros's method in a way that overcomes the problems that arose. To do this, first an investigation into Reyer and Papalambros's mathematical model was conducted, and their equality and inequality equations have been modified. Second, their optimisation model has been represented by its transfer functions. Third, their model's parameters and variables have been reconsidered. Finally, the WF motor/controller system was discretely optimised. Following these developments, the new method was used to optimise the weight and response of a motor/controller system capable of driving a 6 Nm torque in MATLAB to illustrate the developed method and compare its outcome with that achieved by Reyer and Papalambros in 1999. The comparison indicated that the method developed here is superior and the weight and response of the system optimised by this current study outperforms the one developed by Reyer and Papalambros. To confirm the validity of the developed weight optimisation model, the weight of a 50 watt WF DC prototype motor was partially optimised experimentally. This resulted in the weight of this motor being successfully reduced. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1104468 / Thesis (M.Eng.Sc.) -- University of Adelaide, School of Mechanical Engineering, 2004

abstract: Advances in implantable MEMS technology has made possible adaptive micro-robotic implants that can track and record from single neurons in the brain. Development of autonomous neural interfaces opens up exciting possibilities of micro-robots performing standard electrophysiological techniques that would previously take researchers several hundred hours to train and achieve the desired skill level. It would result in more reliable and adaptive neural interfaces that could record optimal neural activity 24/7 with high fidelity signals, high yield and increased throughput. The main contribution here is validating adaptive strategies to overcome challenges in autonomous navigation of microelectrodes inside the brain. The following issues pose significant challenges as brain tissue is both functionally and structurally dynamic: a) time varying mechanical properties of the brain tissue-microelectrode interface due to the hyperelastic, viscoelastic nature of brain tissue b) non-stationarities in the neural signal caused by mechanical and physiological events in the interface and c) the lack of visual feedback of microelectrode position in brain tissue. A closed loop control algorithm is proposed here for autonomous navigation of microelectrodes in brain tissue while optimizing the signal-to-noise ratio of multi-unit neural recordings. The algorithm incorporates a quantitative understanding of constitutive mechanical properties of soft viscoelastic tissue like the brain and is guided by models that predict stresses developed in brain tissue during movement of the microelectrode. An optimal movement strategy is developed that achieves precise positioning of microelectrodes in the brain by minimizing the stresses developed in the surrounding tissue during navigation and maximizing the speed of movement. Results of testing the closed-loop control paradigm in short-term rodent experiments validated that it was possible to achieve a consistently high quality SNR throughout the duration of the experiment. At the systems level, new generation of MEMS actuators for movable microelectrode array are characterized and the MEMS device operation parameters are optimized for improved performance and reliability. Further, recommendations for packaging to minimize the form factor of the implant; design of device mounting and implantation techniques of MEMS microelectrode array to enhance the longevity of the implant are also included in a top-down approach to achieve a reliable brain interface. / Dissertation/Thesis / Ph.D. Bioengineering 2013

Cette thèse propose d'intégrer les principes de la micro-robotique dans un laboratoire sur puce afin d'améliorer les performances du tri cellulaire par diélectrophorèse. Contrôler la trajectoire des cellules dans une puce fluidique en temps réel nécessite de reconcevoir la puce, la modéliser et développer des lois de commande dédiées au contrôle en temps réel. Concernant la conception, cette thèse s’intéresse au compromis existant entre la vitesse de tri et les problématiques de suivi des cellules en temps réel. Une architecture originale basée sur deux plans d’électrodes, sur les faces supérieures et inférieures des canaux, est proposée. Des procédés de fabrication dédiés à cette architecture sont développés. En particulier, la fabrication d'électrodes transparentes et l'assemblage des deux réseaux d'électrodes parallèles sont étudiés. Concernant la modélisation, une formulation analytique du champ électrique découplant variables de commande, termes dépendant de la position de l’objet et termes dépendant uniquement de la géométrie de la puce est proposée afin de calculer rapidement et précisément la force de diélectrophorèse. Une analyse de l'anisotropie des forces de frottement présentes à proximité des électrodes vient compléter la modélisation dynamique du comportement des microparticules, et donne lieu à un modèle compatible avec la commande temps réel, validé expérimentalement sur des objets artificiels. Enfin, un contrôleur basé sur des techniques d’optimisation ainsi qu’un planificateur de trajectoires sont proposés pour le tri de cellules. Un simulateur est développé et met en avant les bonnes performances de tri d’un tel système. L’ensemble de ces méthodes permettront de contrôler la trajectoire de cellules biologiques dans des puces de tri afin d’en améliorer la sélectivité et la rapidité. / This thesis proposes to integrate the principles of micro-robotics in a lab-on-a-chip in order to improve the performance of cell sorting by dielectrophoresis. Controlling the trajectory of cells in a fluidic chip in real time requires redesigning the chip, modeling it and developing control laws dedicated to real-time control. Concerning the design, this thesis is interested in the compromise existing between the speed of sorting and the problems of cell tracking in real time. An original architecture based on two electrode planes, on the upper and lower faces of the channels, is proposed. Manufacturing processes dedicated to this architecture are developed. In particular, the manufacture of transparent electrodes and the assembly of the two parallel electrode arrays are studied. Concerning the modeling, an analytical formulation of the electric field uncoupling control variables, terms depending on the position of the object and terms depending solely on the geometry of the chip is proposed in order to quickly and accurately calculate the dielectrophoresis force. An analysis of the anisotropy of the friction forces present near the electrodes completes the dynamic modeling of the behavior of the microparticles, and gives rise to a model compatible with real-time control, validated experimentally on artificial objects. Finally, a controller based on optimization techniques and a trajectory planner are proposed for cell sorting. A simulator is developed and highlights the good sorting performance of such a system. All of these methods will control the trajectory of biological cells in sorting chips to improve selectivity and speed.