Browsing by Subject "Bandwidth"

Now showing 1 - 2 of 2
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    Approximate Communication - Enhancing compressibility through data approximation
    (2015-11) Suresh, Harini
    The implicit noise tolerance of emerging Recognition, Mining and Synthesis (RMS) applications provides the liberty from conforming to the "correct" output. This attribute can be exploited by introducing inaccuracies to the datasets, to achieve performance benefits. Data compression provides better utilization of the available bandwidth for communication. Higher gains in compression can be achieved by understanding the characteristics of the input data stream and the application it is intended to be used for. We introduce simple approximations to the input data stream, to enhance the performance of existing lossless compression algorithms by gradually and efficiently trading off output quality. For different classes of images, we explain the interaction between the compression ratio and the output quality, time consumed for approximation, compression, and decompression. This thesis demonstrates and quantifies the improvement in compression ratios of lossless compression algorithms with approximation, compared to the state-of-the-art lossy compression algorithms.
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    Force control of a highly inertial specimen.
    (2010-05) Saari, Byron John
    Many servo-hydraulic control applications require high bandwidth realtime force tracking. Some specimen dynamics greatly limit the force bandwidth obtainable with standard PID loops. In these cases, the force control bandwidth is much lower than its position control counterpart. When the specimen includes resonant modes in the frequency range of interest, these resonant poles result in complex zeros in the open loop transfer function, which adversely affect the loop shape. These low frequency complex zeros are a consequence of the “highly inertial specimen” characteristics where the frequency of the zeros is inversely proportional to the square root of the mass. This paper presents a servo-hydraulic model to study this problem and design control laws which are implemented on an experimental test bench. An evaluation of a dynamic inversion controller shows a lack in robustness to model uncertainties. Included in this paper is the design of an H-infinity loop shaping controller which exhibits high gain disturbance rejection and robust stability with an order of magnitude improvement in the force reference tracking bandwidth. The controller also includes an inverse model prefilter, which increases the force reference tracking bandwidth higher than the displacement control (without pre-filter) tracking bandwidth.