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Indiana University-Purdue University Indianapolis (IUPUI) / With the development of the electric mower, an electrical control system is necessary to drive the blades and the traction wheel. This thesis introduces an electrical deck control system. The system includes a high-powered deck controller and a permanent magnet synchronous motor (PMSM). A PMSM control model has been built in MATLAB/Simulink to verify and support the physical design. Three different PWM modulation methods have also been implemented and compared in MATLAB/Simulink. Furthermore, a model for the distribution and features of grass was built based on sampling of Google Street View images. A six-step pulse width modulation (PWM) control strategy was realized using a PIC33 embedded microprocessor. An enhanced closed-loop control system design was implemented to keep a constant blade speed in order to cut grass efficiently.

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This paper considers the control of externally symmetric vector second order systems using an analytical upper bound method. The structural model is a cantilevered aluminum beam with a collocated pair of piezoceramic patches to serve as actuators and sensors. A computationally efficient method for approximating the H-infinity norm for externally symmetric systems is presented. The approximation method is then used to calculate a scalar output feedback controller to guarantee a closed-loop norm less than any user defined value. This method is tested with a finite-element representation of the beam, and then verified experimentally.

Les systèmes multi-agents sont des systèmes dynamiques composés par plusieurs éléments qui interagissent entre eux. Ces éléments sont appelés agents. Un agent est un système dynamique caractérisé par deux propriétés. La première est que les agents sont autonomes— c’est-à-dire qu’ils ne sont pas dirigés par l’environnement extérieur et ils peuvent évoluer selon un comportement auto-organisé. La seconde est que les agents sont capables de communiquer entre eux pour accomplir des tâches complexes, telles que la coopération, la coordination et la résolution de conflits. L’un des problèmes courants concernant les systèmes multi-agents est la synchronisation. Les agents sont synchronisés lorsque leur évolution dans le temps converge vers une trajectoire commune. Plusieurs applications du monde réel peuvent être conceptualisés comme des problèmes de synchronisation des systèmes multi-agents : par exemple, l’alignement en vitesse ( flocking en anglais), et le contrôle de la formation du mouvement de groupes cohérents. La synchronisation des systèmes multi-agents peut être obtenue grâce à différentes techniques de contrôle. Dans cette thèse nous proposons des méthodes de contrôle centralisées et distribuées pour la synchronisation des systèmes multi-agents. Nous développons des conditions nécessaires et suffisantes pour la synchronisation des systèmes multi-agents, composés par des agents identiques et linéaires qui ne changent pas dans le temps, en utilisant une approche Lyapunov. Ces conditions sont utilisées pour la conception de lois de contrôles distribuées. ensuite, nous étendons les résultats aux systèmes multi-agents soumis à des perturbations externes, assurant un niveau de performance désiré grâce à une technique de contrôle de type 퐻 ∞ . enfin, nous étendons l’analyse aux systèmes multi-agents avec contraintes sur les actionneurs, en utilisant des techniques de contrôle anti-windup. Nous évaluons l’efficacité et les performances des stratégies de contrôle proposées dans plusieurs simulations, dont deux d’entre elles sont inspirées par des applications issues du monde réel. La première est le contrôle du vol en formation d’avions, et la seconde est l’analyse de la transmission de contenus vidéo comme un problème de synchronisation. Nous comparons aussi les résultats obtenus avec des techniques de contrôle alternatives. / Multi-agent systems are dynamical systems composed of multiple interacting elements known as agents . Each agent is a dynamical system with two characteristics. First, it is capable of autonomous action—that is, it is able to evolve according to a self-organised behavior, which is not influenced by the external environment. Second, it is able to exchange information with other agents in order to accomplish complex tasks, such as coordination, cooperation, and conflict resolution. One commonly studied problem in multi-agent systems is synchronization. The agents are synchronized when their time evolutions converge to a common trajectory. Many real-world applications, such as flocking and formation control, can be cast as synchronization problems. Agent synchronization can be achieved using different approaches. In this thesis, we propose distributed and centralized control paradigms for the synchronization of multi-agent systems. We develop necessary and sufficient conditions for the synchronization of multi-agent systems, composed by identical linear time-invariant agents, us- ing a Lyapunov-based approach. Then we use these conditions to design distributed synchronization controllers. Then, we extend this result to multi-agent systems subject to external disturbances enforcing disturbance rejection with 퐻 ∞ control techniques. Furthermore, we extend the analysis to multi-agent systems with actuator constraints using LMI-based anti-windup techniques. We test the proposed control design strategies in simulated examples among which two are inspired by real-world applications. In the first, we study airplane formation control as a synchronization problem. In the second, we analyze the delivery of video streams as a synchronization problem and we compare the results to existing controllers.

In nature, through millions of years of evolution, fish and cetaceans have developed fast efficient and highly manoeuvrable methods of marine propulsion. A recent explosion in demand for sub sea robotics, for conducting tasks such as sub sea exploration and survey has left developers desiring to capture some of the novel mechanisms evolved by fish and cetaceans to increase the efficiency of speed and manoeuvrability of sub sea robots. Research has revealed that interactions with vortices and other unsteady fluid effects play a significant role in the efficiency of fish and cetaceans. However attempts to duplicate this with robotic fish have been limited by the difficulty of predicting or sensing such uncertain fluid effects. This study aims to develop a gait generation method for a robotic fish with a degree of passivity which could allow the body to dynamically interact with and potentially synchronise with vortices within the flow without the need to actually sense them. In this study this is achieved through the development of a novel energy based gait generation tactic, where the gait of the robotic fish is determined through regulation of the state energy rather than absolute state position. Rather than treating fluid interactions as undesirable disturbances and `fighting' them to maintain a rigid geometric defined gait, energy based control allows the disturbances to the system generated by vortices in the surrounding flow to contribute to the energy of the system and hence the dynamic motion. Three different energy controllers are presented within this thesis, a deadbeat energy controller equivalent to an analytically optimised model predictive controller, a $H_\infty$ disturbance rejecting controller with a novel gradient decent optimisation and finally a error feedback controller with a novel alternative error metric. The controllers were tested on a robotic fish simulation platform developed within this project. The simulation platform consisted of the solution of a series of ordinary differential equations for solid body dynamics coupled with a finite element incompressible fluid dynamic simulation of the surrounding flow. results demonstrated the effectiveness of the energy based control approach and illustrate the importance of choice of controller in performance.