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Browsing by Subject "Control system"

Now showing 1 - 2 of 2
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    Design, modeling, and control of a novel architecture for automatic transmission systems
    (2013-06) Mallela, Virinchi
    Automotive transmissions are required to efficiently transfer energy from the engine to the wheels. Automatic transmissions are one of the most widely used transmission systems in the United States. This transmission houses a hydraulic system which is used to actuate the clutch system to realize different gear ratios. Currently, these clutches are primarily controlled in open-loop using hydraulic valves in a physical embodiment designed specifically for a given transmission system in order to perform precise pressure and flow control. To meet the increasing demand for higher fuel economy, transmissions with greater number of gear ratios are being introduced. The hydraulic architecture is becoming increasingly complicated with more clutches and control elements. With the advancement of MEMS technology, the sensor-based direct feedback control of clutches becomes possible. This paper first analyzes the current architecture of transmission hydraulic system and then presents a new architecture for the feedback-based clutches. The proposed architecture is further validated through experiments using hardware-in-the-loop system.
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    Experimental study of control laws for supercavitating vehicles.
    (2012-03) Hjartarson, Arnar
    Supercavitation is when a cavity is made to envelop a submerged body. Supercavitation can be used to achieve an order of magnitude reduction in drag on underwater vehicles. Supercavitating vehicles can reach unprecedented speeds underwater. Supercavitation has reportedly been used to create underwater vehicles that reach speeds of 370 km/h, which is significantly faster than the fastest traditional submarine vehicles. Methods and technologies to control and maneuver supercavitating vehicles are actively being researched. The efforts to develop control strategies and assess the effectiveness of control effectors are hampered by a lack of access to working test beds and operational vehicles. This thesis describes the development and testing of an experimental test bed for validating the performance of control strategies for supercavitating vehicles. The test bed addresses the need for an experimental platform that enables researchers to test candidate control algorithms and associated technologies on a real, physical, supercavitating system. The test bed was used to evaluate the performance of feedback control systems on a model supercavitating vehicle in a water tunnel. Two controllers were developed using H∞ control design techniques and evaluated on the test bed. The validity of the hydrodynamic model that the control designs were based on was established, and a comparison and partial validation of their performance was obtained in water tunnel experiments. The experiments demonstrated that a test bed of this kind can be used to evaluate control algorithms, and study the effects of active control systems on a supercavitating vehicle.