Browsing by Subject "Nonlinear mechanics"
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Item Adaptive output feedback controllers for a class of nonlinear mechanical systems(2002) Miwa, Hideaki; Akella, Maruthi Ram, 1972-Even from the early days of adaptive control theory, it has been a primary target for several researchers to guarantee global stability using as limited assumptions as possible. Currently, there exist applicable theories for output feedback adaptive control with which we can often guarantee only semi-global stability. When compared to the corresponding non-adaptive (deterministic) case, these solutions need several extra assumptions in the synthesis of the adaptive controller. In this dissertation, we introduce the definition of a specific class of nonlinear systems, which can be guaranteed global asymptotical stability. This is one of the main result of this dissertation. We named this class as “Passivity Based Globally Stabilizable Systems via Adaptive Output feedback(PBGSS/AOF)”. During the arguments, we show how to construct passivity based adaptive controller. As examples of actual systems, spacecraft attitude control problem and n degree of freedom(DOF) robot arm problem are chosen. For each case, The method to construct a controller and an estimator is shown with its stability proof and its effectiveness is displayed with numerical simulation results.Item The effective granular temperature based on the fluctuation-dissipation theorem(2007-08) Buck, Alexander, 1983-; Swinney, H.L., 1939-Dissipative granular systems that are driven continuously by an external forcing, like vertical shaking or fluid flow pulses, exhibit fluid like properties. Different definitions of granular temperature have been proposed for these systems, in analogy to regular fluids of microscopic particles. On the road to creating a setup for measuring both the temperature based on the fluctuation-dissipation theorem TFD and the kinetic temperature Tkin, experiments to measure TFD of a water-fluidized bed of glass beads (d = 250 μm) were performed with a torsion oscillator. For low flow rates around the onset of fluidization, (flow rate Q ∼ 0.30 ml/s) the temperature was on the order of kBTFD ∼ 10−16 J and showed a linear increase with the flow rate. A sharp increase of the damping of the torsion oscillator was found for decreasing flow rates around the onset of fluidization, which can be interpreted as the approach to a glassy regime of the fluidized bed.Item Switching output stages for direct PCM-PWM amplification with enhanced PSRR and THD performance(Texas Tech University, 2003-12) Pate, Michael ScotThis thesis describes the process involved in designing the loop filter that is required when changing a class-D power output stage from a full-bridge configuration to a half-bridge. The loop filter designed is part of an error correction feedback network. This thesis covers the basic theoretical derivations for the device, complete circuit design and simulation and basic device layout considerations. Ideas for future versions are given for reference.