The electromyogram (EMG) signal is desired to be used as a control signal for applications such as multifunction prostheses, wheelchair navigation, gait generation, grasping control, virtual keyboards, and gesture-based interfaces [25]. Several research studies have attempted to relate the electromyogram (EMG) activity of the forearm muscles to the mechanical activity of the wrist, hand and/or fingers [41], [42], [43]. A primary interest is for EMG control of powered upper-limb prostheses and rehabilitation orthotics. Existing commercial EMG-controlled devices are limited to rudimentary control capabilities of either discrete states (e.g. hand close/open), or one degree of freedom proportional control [4], [36]. Classification schemes for discriminating between hand/wrist functions and individual finger movements have demonstrated accuracy up to 95% [38], [39], [29]. These methods may provide for increased amputee function, though continuous control of movement is not generally achieved. This thesis considered proportional control via EMG-based estimation of finger forces with the goal of identifying whether multiple degrees of freedom of proportional control information are available from the surface EMG of the forearm. Electromyogram (EMG) activity from the extensor and flexor muscles of the forearm was sensed with bipolar surface electrodes and related to the force produced at the four fingertips during constant-posture, slowly force-varying contractions from 20 healthy subjects. The contractions ranged between 30% maximum voluntary contractions (MVC) extension and 30% MVC flexion. EMG amplitude sampling rate, least squares regularization, linear vs. nonlinear models and number of electrodes used in the system identification were studied. Results are supportive that multiple degrees of freedom of proportional control information are available from the surface EMG of the forearm, at least in healthy subjects. An EMG amplitude sampling frequency of 4.096 Hz was found to produce models which allowed for good EMG amplitude estimates. Least squares regularization with a pseudo-inverse tolerance of 0.055 resulted in significant improvement in modeling results, with an average error of 4.69% MVC-6.59% MVC (maximum voluntary contraction). Increasing polynomial order did not significantly improve modeling results. Results from smaller electrode arrays remained fairly good with as few as six electrodes, with the average %MVC error ranging from 5.13%-7.01% across the four fingers. This study also identified challenges in the current experimental study design and subsequent system identification when EMG-force modeling is performed with four fingers simultaneously. Methods to compensate for these issues have been proposed in this thesis.

Recent technological developments have implemented the use of proportional control in prosthetic hands, giving rise to the importance of appropriate myoelectric control. EMG models in the past have assumed a linear proportionality to simplify the EMG-force relationships. However, it has been shown that a non-linear EMG-force relationship may be a more effective model. This study focused on evaluating three different control algorithms for a novel myoelectric training device, consisting of a toy car controlled by EMG signals from the distal muscles in the arm. Sixteen healthy adult subjects (5 male and 11 female) with an average age of 23.6 years (SD = 2.7) were asked to drive the car through a slalom course. Completion times as well as number of errors (wall hits, cone hits, and reversals) were recorded to evaluate performance. The NASA TLX was administered to evaluate psychometrics such as mental demand, physical demand, frustration, and overall workload. The average total errors per trial on the final day of testing using the linear proportional algorithm was found to be statistically significantly (p < 0.05) lower than digital and non-linear proportional. The average course completion time per trial and overall workload using the non-linear proportional algorithm was found to be statistically significantly (p < 0.05) lower than digital and linear proportional. These results suggest that a non-linear algorithm would be most appropriate for myoelectric control in prosthetic hands.

The need for mechanisms that assist human movements has been increasing due to the rising number of people that has some kind of movement disability. In this scenario, it is of great importance the development of control methods that assist the interface between a motor assistive device and its user. This work proposes a controller for an exoskeleton with one degree of freedom, using surface electromyography signals from the user as the input signal. An exoskeleton was adapted to serve as platform for the developed control method. To create an EMG-to-Angle model, a set of experiments were carried out with six subjects. The experiment consisted of a series of continuous and discrete elbow flexion and extension movements with different load levels. Using the experimental data, linear (ARIMAX) and non linear (Hammerstein-Wiener) system identification methods were evaluated to determine which is the best candidate for the estimation of the EMG-to-Angle model, based on its accuracy and ease of implementation. A new experiment wasconducted to develop a real-time controller, based on FIR model and tested in a real-timeapplication. Tests showed that the controller is capable of estimating the elbow joint angle with correlation above 70% and root-mean-square error below 25° when compared to the measured elbow joint angles. / A necessidade por mecanismos que auxiliam os movimentos do ser humano vem crescendo devido ao aumento do número de pessoas portadores de deficiências que afetam a capacidade motora. Nesse cenário, é de grande importância o desenvolvimento de métodos de controle que auxiliem a interface entre o dispositivo de assistência motora e o seu usuário. Esse trabalho propõe um controlador para um exoesqueleto com um grau de liberdade, usando sinais de eletromiografia de superfície do usuário como sinal de entrada. Um exoesqueleto foi adaptado para servir de plataforma para o método de controle desenvolvido. Para criar um modelo EMG-ângulo, um conjunto de experimentos foi conduzido com seis voluntários. O experimento consistiu em uma série de movimentos de flexo-extensão do cotovelo contínuos e discretos com diferentes níveis de carga. Utilizando os dados do experimento, métodos de identificação de sistemas linear (ARIMAX) e não linear (Hammerstein-Wiener) foram avaliados para determinar qual o melhor candidato para a estimação do modelo EMG-ângulo, baseado em sua acurácia e facilidade de implementação. Um novo experimento foi conduzido para desenvolver um controlador em tempo real, baseado no modelo FIR e testado em uma aplicação em tempo real. Testes indicaram que o controlador é capaz de estimar o ângulo da junta do cotovelo com valores de correlação acima de 70% e raiz do erro quadrático médio menor que 25º, quando comparados aos valores medidos de ângulo da junta do cotovelo.

In the past few years, due to the rapid advance in technology and the aid of 3D graphics applications the world of 3D graphics is rapidly expanding from desktop computers and dedicated gaming consoled to handheld devices, such as cellular phones, PDAs, laptops etc.,. However, unlike traditional desktop computers and gaming consoles, mobile computing devices typically have slower processors that have less capability for handling large computation-intensive workloads like 3D graphics application. In addition, the power consumption is one of the major design specifications to realize the 3D graphics accelerating engine for mobile devices because handheld batteries have limited lifetimes. Moreover, the size of chip is depend on the Moore¡¦s Law: The number of transistors in a chip are double in every eighteen months. Even though the produce cost is decrease, but the capacity of battery cannot increase like the transistors. Therefore, how to reduce power consumption by using efficient power management techniques has become a very important research topic in 3D graphics SoC design. For 3D graphics applications, dynamic voltage and frequency scaling (DVFS) is a good candidate to reduce the power consumption of 3D graphics accelerating engine. So many relative papers have researched in how to accurately predict the workload and scale the voltage and frequency. The prediction policy can divide into History-based predictor [1] and Frame-structure predictor [2-4]. The History-based predictor predicts the latter frame workload by previous frame workload to scale the voltage, and the frame-structure predictor performs offline and then determine the different kind of frame for an application. A table is used to save the mapping of different kind of frame to the voltage, and then the voltage is scaled according to the mapping table. A lot of researchers put the power management policy in software i.e. processors, but our proposed workload prediction scheme has been realized into the hardware circuit. Therefore, it can not only reduce the overhead of processor but also quickly adjust the voltage and frequency of 3D graphics accelerating engine. Our prediction policy is one of the History-based predictor ,and it is an adaptive PID predictor [5-6] in which the parameters of Proportional controller and Integral controller can be adaptively adjusted so that it can obtain more accurate prediction results than non-adaptive predictor. In general, the workload that the selected voltage can handle is usually over than the predicted workload. That is, actual workload is usually less than predicted workload. So that the slack time will be generated. We can utilize the slack time through Inter-frame compensation [7-10] to save more energy while maintaining the similar output quality. We use a simple policy to adaptively select the parameters for compensation between the frames to simplify the hardware architecture of the power management policy. Experimental results show that, we can get more energy saving and more accurate workload prediction when the adaptive PI predictor and adaptive Inter-frame compensation are utilized.

<p>Dat je pregled mogućnosti za povišenje energetske efikasnosti<br />pneumatskog programabilnog manipulatora primenjenog u kontaktnim<br />zadacima. Projektovano je i realizovano ispitno postrojenje. Posebno<br />je ukazano na mogućnosti projektovanja različitih upravljačkih<br />sistema. Razvijeni su primeri PWM i proporcionalnog upravljanja.<br />Ispitana su predložena rešenja iz različitih aspekata energetske<br />efikasnosti i kvaliteta praćenja trajektorije pri korišćenju<br />različitih vrsta materijala i alata. Izvučeni su potrebni zaključci.</p> / <p>This paper contains an overview of possibilities for increasing the energy<br />efficiency of programmable pneumatic manipulator in contact tasks.<br />Experimental station is designed and realized as a testbed. Especially, point<br />is on possibilities of designing of new control systems. Examples of PWM<br />and proportional control are developed. Proposed solutions are examined<br />from aspects of energy efficiency and quality of trajectory tracking, by using<br />various types of materials and tools. Necessary conclusions are drawn.</p>

Magnetic shape memory alloys are active materials which deform under the application of a magnetic field or an external stress. Due to their internal friction, recognizable from the strain-stress hysteresis, this new material technology allows the design of multistable actuators. This paper describes and characterizes an innovative airflow control valve whose aperture is proportional to the deformation of the active material and thus controllable by the input voltage. The multistability of the material is partially exploited within an airflow control loop to reduce the energy losses of the valve when a specific airflow value must be hold.

La capacité de réaliser des tâches robotiques dextres à l'échelle nanométrique dans un microscope électronique à balayage (MEB) est un enjeu crucial pour les nanotechnologies. Les systèmes nano-robotiques dédiés à des applications sous MEB ont ainsi émergé dans de nombreux laboratoires de robotique. Ils peuvent être composés d'un ou de plusieurs actionneurs intégrés à des plateformes nano-robotiques avec un ou plusieurs effecteurs. L’actionneur Piézoélectrique Stick-Slip (PSS) est l'un des meilleurs candidats pour actionner les systèmes nano-robotiques dédiés à des applications sous MEB car il est capable d'effectuer un positionnement grossier avec une plage de déplacement millimétrique et un positionnement précis avec une plage de déplacement de quelques micromètres. La modélisation des actionneurs PSS est complexe notamment en raison de leur mode de fonctionnement hybride. La commande est également difficile à cause de plusieurs caractéristiques liées aux actionneurs PSS, soient le frottement, l’hystérésis et les vibrations non-amorties, qui dégradent leur performances en termes de précision et de vitesse. Ce travail porte sur la modélisation et la commande d'un système nano-robotique à 3 axes dédié à des applications sous MEB et actionné par des actionneurs piézoélectriques de type stick-slip. Chaque élément et caractéristique des actionneurs PSS ont été analysés et modélisés afin d’établir par la suite un modèle dynamique complet capable de décrire les deux modes de fonctionnement, à savoir le mode balayage et pas à pas. Pour chacun de ces deux modes, des lois de commande ont ainsi été développées pour les actionneurs PSS. Des stratégies de commande robuste ont été synthétisées pour des objectifs de positionnement rapide et à haute résolution en mode balayage. De telles performances sont fondamentales dans plusieurs tâches micro-/nano-robotique tels que le nano-assemblage rapide et précis et la nano-caractérisation des matériaux. Une commande proportionnelle en fréquence et en amplitude est synthétisée pour effectuer un déplacement millimétrique en mode pas à pas. Ceci est motivé par les applications robotiques pour lesquelles une large plage de déplacement est requise, tels que le scan de grandes surfaces et les phases d’approche d’une sonde d’un échantillon à manipuler. Une stratégie de commutation qui combine les modes balayage et pas à pas, est alors proposée pour remédier au manque de précision en mode pas à pas, lors de passage d’un grand à un petit déplacement. Ce travail a donné lieu à des résultats qui ouvrent de nouvelles perspectives pour l'utilisation des actionneurs PSS dans les systèmes nano-robotiques dédiés à des applications sous MEB. / The capability of doing dexterous robotic tasks at the nanometer scale inside a Scanning Electron Microscope (SEM) is a critical issue for nanotechnologies. SEM-integrated nano-robotic systems have consequently emerged in many robotics laboratories. They can be composed of one or more actuators assembled into nano-robotic platforms with one or several effectors. Piezoelectric Stick-Slip (PSS) actuators is one of the best candidate to actuate SEM-integrated nano-robotic systems because it is able to perform coarse positioning with millimeter displacement range and fine positioning with travel range of few micrometers. Modeling of PSS actuators is complex and difficult mainly because of their hybrid operating mode. Furthermore, control is challenging due to several characteristics related to PSS actuators, namely friction, hysteresis and undamped vibrations, which degrade their performance in terms of precision and speed. This work deals with modeling and control of a 3-axes SEM integrated nano-robotic system driven by piezoelectric stick-slip actuators. Each element and characteristic of PSS actuators are analyzed and modeled to thereafter establish a complete dynamic model able to describe the two functioning modes, namely the scanning and the stepping modes. PSS actuators are then controlled in each of these modes. Robust control strategies are developed to achieve high-resolution and fast positioning in scanning mode. Such performance is fundamental in several micro/nano-robotic tasks such as fast and accurate nano-assembly and nano-material characterization. A frequency/amplitude proportional controller is designed to perform millimeter displacement in stepping mode. This is motivated by robotic tasks where large motion is required, such as large surfaces scan and bringing a probe close to a sample to manipulate. A switched strategy, which combines scanning and stepping motion modes, is then proposed to remedy to the lack of precision in stepping motion, when passing from a large to a small displacement. This work has given rise to results which open new perspectives to the use of PSS actuators in SEM integrated nano-robotic systems.