Browsing by Author "Song, Xubin"
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- Design of Adaptive Vibration Control Systems with Applicaion to Magneto-Rheological DampersSong, Xubin (Virginia Tech, 1999-11-11)The design of nonlinear adaptive control systems for reducing vibration transmission in applications such as transportation systems is discussed. The systems studied include suspension systems, such as those used in vehicles, employing nonlinear magneto-rheological (MR) dampers that are controlled to provide improved vibration isolation. Magneto-rheological dampers use a novel class of smart fluid whose apparent viscosity changes as it is exposed to a magnetic field. The developed adaptive control scheme is designed to deal with the nonlinearities and uncertainties that commonly arise in most suspension applications. Some of the nonlinearities that are considered include time-varying characteristics, displacement-dependent effects, and hysterisis damping of magneto-rheological dampers. The uncertainties include mass and stiffness variations that can commonly occur in a suspension system. A number of nonlinear analytical models are developed and used in numerical simulation to evaluate the validity and effectiveness of the developed adaptive controllers. Further, the results of the numerical study are used in an experimental evaluation of the controllers on a seat suspension for heavy vehicles. The analytical and experimental evaluation both indicate the effectiveness of the proposed adaptive control technique in controlling vibration transmission in the presence of both system nonlinearities and uncertainties. The manuscript will provide a detail account of the modeling, dynamic analysis, adaptive control development, and testing that was performed throughout this study.
- No-jerk semi-active skyhook control method and apparatus(United States Patent and Trademark Office, 2000-09-05)A method of controlling a controllable force generator within a controllable suspension system interconnected between a first member M.sub.1 and a second member M.sub.2. The method includes the steps of obtaining a first signal (V.sub.abs) representative of the absolute velocity of the first member M.sub.1, obtaining a second signal (V.sub.rel) representative of the relative velocity between the first and second members, and setting a desired damping force for the generator based upon a control policy which defines a control surface. The control policy includes a preselected gain, an absolute velocity, and a shaping function of relative velocity wherein said control surface exhibits only continuous first derivatives for V.sub.rel *V.sub.abs >0 and wherein the control surface is devoid of any surface discontinuities. This control policy effectively eliminates the jerkiness in certain prior art control methods, such as skyhook.