This paper proposes an analytical methodology for the optimal design of a magnetorheological (MR) valve structure. The MR valve structure is constrained in a specific volume and the optimization problem identifies geometric dimensions of the valve structure that maximize the yield stress pressure drop of a MR valve or the yield stress damping force of a MR damper. In this paper, the single-coil and two-coil annular MR valve structures are considered. After describing the schematic configuration and operating principle of a typical MR valve and damper, a quasi-static model is derived based on the Bingham model of a MR fluid. The magnetic circuit of the valve and damper is then analyzed by applying Kirchoff’s law and the magnetic flux conservation rule. Based on quasi-static modeling and magnetic circuit analysis, the optimization problem of the MR valve and damper is built. In order to reduce the computation load, the optimization problem is simplified and a procedure to obtain the optimal solution of the simplified optimization problem is presented. The optimal solution of the simplified optimization problem of the MR valve structure constrained in a specific volume is then obtained and compared with the solution of the original optimization problem and the optimal solution obtained from the finite element method.
This paper focuses on the optimal design of a compact and high damping force engine mount featuring magnetorheological fluid (MRF). In the mount, a MR valve structure with both annular and radial flows is employed to generate a high damping force. First, the configuration and working principle of the proposed MR mount is introduced. The MRF flows in the mount are then analyzed and the governing equations of the MR mount are derived based on the Bingham plastic behavior of the MRF. An optimal design of the MR mount is then performed to find the optimal structure of the MR valve to generate a maximum damping force with certain design constraints. In addition, the gap size of MRF ducts is empirically chosen considering the ‘lockup’ problem of the mount at high frequency. Performance of the optimized MR mount is then evaluated based on finite element analysis and discussions on performance results of the optimized MR mount are given. The effectiveness of the proposed MR engine mount is demonstrated via computer simulation by presenting damping force and power consumption.
This paper presents a semi-active seat suspension with an electrorheological (ER) fluid damper. A cylindrical ER seat damper is devised on the basis of a Bingham model of an arabic gum-based ER fluid and its field-dependent damping characteristics are empirically evaluated. A semi-active seat suspension is then constructed, and the governing equations of motion are derived by treating the driver mass as a parameter uncertainty. A sliding mode controller, which has inherent robustness to system uncertainties, is formulated to attenuate seat vibration due to external excitations. The controller is then experimentally realized, and controlled responses are presented in both time and frequency domains. In addition, a full-car model consisting of primary, cabin, and seat suspensions is established, and a hardware-in-the-loop simulation is undertaken to demonstrate a practical feasibility of the proposed seat suspension system showing ride comfort quality under various road conditions.
This paper presents vibration and position control of a flexible beam structure by adopting shape memory alloy (SMA) wire actuators. The governing equation of motion of the proposed flexible structure is obtained via Hamilton's principle. The dynamic characteristics of the SMA wire actuator are experimentally identified and incorporated with the governing equation to furnish a control system model in the state space. Subsequently, a sliding mode controller which has inherent robustness to external disturbances and parameter uncertainties is formulated. The controller is then empirically realized for vibration control with relatively large tip displacement. In addition, tip position tracking control to follow desired trajectories with low-frequency sine and square waves is undertaken. Control performances such as tracking error are evaluated through both computer simulation and experimental investigation in time domain.
This work presents a new design for adaptive fuzzy sliding-mode control based on two methodologies, namely H∞ control and sliding-mode control, and its control effectiveness. This is achieved by implementing a control scheme for vibration control of a vehicle with a seat suspension on which a magnetorheological damper is installed. The sliding surface of sliding-mode control is analysed by separation into two matrices: a Hurwitz-constants matrix and a constant matrix. These matrices are the basis for establishing the proposed control scheme combined with the H∞ technique. The control scheme consisting of the combination of H∞ control and sliding-mode control is reinforced by a new robustness function featuring an exponential function. In this work, a fuzzy logic model, which is well known to be an excellent model for uncertain dynamic systems, is integrated with the proposed control algorithm. The fuzzy logic model adopted in this work is an interval type-2 fuzzy model featuring fast computation of the output. The effectiveness of the proposed control scheme is evaluated through both computer simulations and experimental realization on a vehicle with a seat suspension which is equipped with a magnetorheological damper. In addition, in this work, two existing adaptive controllers are modified and implemented for comparative work with the proposed control scheme. It is shown that the proposed control scheme exhibits a much better vibration control performance than the two existing adaptive controllers do.
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