Apesar de o termo Compilador de Silício ser recente, as idéias envolvidas na sua construção são antigas e conhecidas. Este trabalho apresenta todos os passos para a construção do CSAR, um compilador de silício voltado à execusão de operações paralelas. A arquitetura alvo gerada pelo CSAR é distribuída, bem como os algoritmos implementados.

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Apesar de o termo Compilador de Silício ser recente, as idéias envolvidas na sua construção são antigas e conhecidas. Este trabalho apresenta todos os passos para a construção do CSAR, um compilador de silício voltado à execusão de operações paralelas. A arquitetura alvo gerada pelo CSAR é distribuída, bem como os algoritmos implementados.

Resumo não disponível

In this work we propose a number of relevant engineering applications that exhibit both a continuous and a discrete evolution, and are therefore suitably described by a recent formalism for hybrid dynamical systems. More specifically, (i) we design observer schemes for a nonsmooth disturbance arising in AC/DC conversion, which we then cancel from a desirable signal; (ii) we show how reset actuation applied to nonlinear mechanical systems can at the same time sustain or damp oscillations; (iii) we study the feedback interconnection of a classical proportional-integral-derivative controller with a sliding mass under Coulomb friction through differential inclusions. In the context of dynamical systems, we analyze the properties of these applications in terms of asymptotic stability through Lyapunov functions tailored for hybrid systems. Instead of the standard Lyapunov conditions, we prove asymptotic stability through weaker, or relaxed, conditions that are compensated by additional (structural) properties that may be easier to verify.

Hybrid dynamical systems are dynamical systems in which continuous and discrete evolutions coexist and interact. Their twofold nature makes them particularly powerful for both describing and synthesizing complex dynamical behaviors. In this work we exploit this capability for designing innovative control and estimation algorithms that cope with challenges in aerospace applications. In particular: 1. we propose different impulsive control strategies for the problem of close-range rendezvous between two spacecrafts in elliptic orbits; 2. we design a robust time-sub-optimal controller for a class of linear systems emerging in aerospace applications where the control input is limited in magnitude; 3. we synthesize an observer to estimate the speed of rotary systems providing angular measurements that evolve on the unit circle. To this end, we make use of a recent formalism tailored to hybrid dynamical systems for both modeling and proving desirable properties of the proposed algorithms, which are as well confirmed by simulative and experimental validations.

In this thesis we study linear time-invariant systems feedback interconnected with three specific nonlinear blocks; a play/stop operator, a switching-reset mechanism, and an adaptive dead-zone. This setup resembles the Lure problem studied in the absolute stability framework, but the types of nonlinearities considered here do not satisfy (in general) a sector condition. These nonlinear blocks give rise to a whole range of interesting phenomena, such as compact sets of equilibria, hybrid omega-limit sets, and state constraints. Throughout the thesis, we use the hybrid systems formalism to describe these phenomena and to analyze these loops. We obtain sharp stability conditions that can be formulated as linear matrix inequalities, thus verifiable with numerically efficient solvers. Finally, we apply the theoretical findings to two automotive applications.

Model Predictive Control (MPC) is the de facto standard in advanced industrial automation systems. There are two main formulations of the MPC algorithm: an implicit one and an explicit MPC one. The first requires an optimization problem to be solved on-line, which is the main limitation when dealing with hard real-time applications. As the implicit MPC algorithm cannot be guaran- teed in terms of execution time, in many applications the explicit MPC solution is preferable. In order to deal with systems integrating mixed logic and dynam- ics, the class of the hybrid and piecewise affine models (PWA) were introduced and tackled by the explicit MPC strategy. However, the resulting controller complexity leads to a requirement on the CPU/memory combination which is as strict as the number of states, inputs and outputs increases. To reduce drasti- cally the complexity of the explicit controller while preserving the controller’s performance, a strategy combining switched MPC with discontinuous simpli- cial PWA models is introduced in this thesis. The latter is proven to be circuit implementable, e.g., in FPGA. To ensure that closed-loop stability properties are guaranteed, a stability analysis tool is proposed which exploits suitable and possibly discontinuous PWA Lyapunov-like functions. The tool requires solving offline a linear programming problem. Moreover, the tool is able to compute an invariant set for the closed-loop system, as well as ultimate boundedness and input-to-state stability properties.

Autonomous driving is an important research field and presents several problems with different nature and complexity. The goal of this work is describing such problems and the concerning solutions adopted while developing an experimental vehicle designed to autonomously perform some manoeuvres and/or to be remotely driven: the vehicle RUMBy. The problem has been faced from its beginning, i.e. from the hardware and software design: the requisites the system should satisfy are discussed, such as the vehicle and the sensors chosen, and the adopted hardware and software architectures are then described. Some mathematical models representing the vehicle dynamics are also presented, that have been employed in several applications, from the dynamic behaviour simulation up to the control system synthesis. Each model besides presents characteristic parameters that should be evaluated: therefore the problem of identification is discussed in detail, accompanied by the results obtained during an experimental activity carried out in collaboration with a Japanese research institute. Also the vehicle state estimation constitutes a key point in autonomous driving field: about this, the experimental results yielded by an estimation algorithm, based on a Kalman filter, are presented and discussed. Finally, the yaw rate control problem is examined, which is fundamental for both the motion stabilization (during remote driving) and for the following of yaw rate reference profiles (while performing autonomous manoeuvres). Two control architectures, based on a disturbance observer, have been developed and compared in a simulation campaign, that has been carried out by means of a static simulator which reproduces the driving of RUMBy in a virtual environment. This work aims then at marking a milestone within a work in progress, as well as at representing a potential guideline for researchers that would coping with projects concerning autonomous driving.

Haptic devices are becoming a common and significant tool in the perspective of robotic neurorehabilitation for motor learning, particularly in post-stroke patients. As a standard approach, this kind of devices are used in a local environment, where the patient interacts with a virtual environment recreated in the computer's screen. In this sense, a general framework for virtual reality based rehabilitation was developed. All the features of the framework, such as the control loop and the external communication, as well as the haptic and graphic rendering, were implemented inside Matlab/Simulink using Handshake proSENSE toolbox, guaranteeing a real-time system. As an example, a five-bar linkage haptic device with two active degrees-of-freedom (DOF) was designed and integrated within the proposed framework, as well as a device for grasping operations. An extension of this standard approach is verified when the therapist is allowed to feel and interact remotely and in real time with the patient. We applied the proposed concept to a single degree-of-freedom master/slave system. One hand orthosis was used as a master device at the therapist's side, while the other was applied to the patient's hand, and used as a slave device. In order to achieve this issue, we proposed two bilateral control systems in order to guarantee an stable interaction between the master and the slave, even in case of variable network conditions (i.e. Internet). By using the master device, the therapist can remotely move the patient's hand and, at the same time, perceive the patient's resistance to the motion, allowing the assessment of important parameters, such as the residual level of spasticity. In this way, it can be remotely assessed the conditions of the patient and consequently can be proposed a proper rehabilitation program.