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Neuro-fuzzy control of vertical vibrations in railcars using magnetorheological dampers
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Control of vertical vibrations in a railcar is a critical issue that has been addressed by many researchers in the past. This thesis presents a new approach to solving the problem by using a semi-active viscous damper in tandem with a neuro-fuzzy controller. A pair of magnetorheological (MR) dampers is designed and installed in a rail truck. Two neuro-fuzzy systems, Adaptive Neuro-Fuzzy Inference System (ANFIS) and Neuro Fuzzy Controller (NEFCON), are used to emulate behavior of the MR dampers and to train a controller fuzzy inference system (FIS), respectively. In order to design the dampers, a series of numerical simulations is conducted for a fully loaded railcar traveling over a wide range of velocities to estimate the magnitude of critical accelerations. A variety of damping coefficients are assumed for a linear viscous damper to determine the force requirements of the MR dampers. Based on design parameters provided by Lord Corporation, two MR dampers are fabricated and assembled. These dampers are tested extensively in a laboratory and data obtained from these tests are used to train, test, and validate a fuzzy model of each damper. Two controller FIS are trained using NEFCON in a numerical environment to send a time varying voltage signal to the two MR dampers during motion in the railcar. Determination of the voltage signal to the dampers is based solely on feedback from accelerometers attached to the railcar. A detailed parametric study is carried out to evaluate the effectiveness of the fuzzy controllers in reducing vibrations of a railcar for different haul conditions. The performance of MR dampers in their passive-off, passive-on, and semi-active operating condition is compared with that of four linear viscous dampers. Finally, an idealized model of each MR damper is developed and the ability of each corresponding controller to reduce vibrations is also evaluated. Results indicate that the semi-active vibration control strategy can reduce vibrations of the railcar to within a specified limit, provided that a sufficient level of resisting force is applied by both dampers. Further research into full-scale field-testing of railcars with MR dampers installed in them is advocated.
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Includes bibliographical references (leaves 140-144).
Issued also on microfiche from Lange Micrographics.
Atray, Vipul Sunil (2002). Neuro-fuzzy control of vertical vibrations in railcars using magnetorheological dampers. Master's thesis, Texas A&M University. Available electronically from
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