The work in this paper presents techniques for design, development, and control of hybrid electric vehicles (HEV's). Toward these ends, four issues are explored. First, the development of HEV's is presented. This synopsis includes a novel definition of degree of hybridization for automotive vehicles. Second, a load-leveling vehicle operation strategy is developed. In order to accomplish the strategy, a fuzzy logic controller is proposed. Fuzzy logic control is chosen because of the need for a controller for a nonlinear, multidomain, and time-varying plant with multiple uncertainties. Third, a novel technique for system integration and component sizing is presented. Fourth, the system design and control strategy is both simulated and then implemented in an actual vehicle. The controller examined in this study increased the fuel economy of a conventional full-sized vehicle from 40 to 55.7 mi/h and increased the average efficiency over the Federal Urban Driving Schedule from 23% to 35.4%. The paper concludes with a discussion of the implications of intelligent control and mechatronic systems as they apply to automobiles.Index Terms-Automotive control, hybrid vehicle control, intelligent control of automobiles.
Conventional shear mode transmission clutches using magnetorheological fluids (MRFs) can be either disc-shaped or cylindrical. The major drawbacks of these devices include the effect of centrifuging at high rotational speeds and the subsequent sealing problems associated with it. This study develops models aimed at describing centrifuging and mitigates this issue by developing a MR clutch design where the fluid is encapsulated in a highly absorbent polyurethane foam.
The piezoceramic, lead zirconate titanate (PZT), is capable of producing large voltages with relatively minimal currents in response to an applied mechanical load when employed in initially curved laminates. This study addresses the issue of optimizing design parameters of a curved PZT unimorph to maximize charge generation due to mechanical loading. A horizontally placed PZT unimorph structure generates surface charge when vertically loaded and the charge can be collected using charge-collecting circuitry. In order to identify and optimize the variables fundamental to the design process, an analytical model of the curved PZT unimorph was developed using shallow thin shell theory and linear piezoelectric constitutive equations. An expression for charge generation was then derived in terms of geometrical dimensions, material properties and applied loading. The model was experimentally verified with samples consisting of different geometries and loadings. Finally, the analytical model was used to generate optimal design characteristics or ‘rules of thumb’ necessary for optimum design. It is envisioned that these ‘rules of thumb’ will be used by practitioners to design efficient charge generating devices.
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