Variable Damping and Stiffness Vibration Control with Magnetorheological Fluid Dampers for Two Degree-of-Freedom System

Abstract

Vibration isolation methods that vary damping and stiffness have demonstrated excellent authority over system vibration, thus, potentially making them attractive for many applications. However, conventional devices for controlling variable stiffness are typically complicated and difficult to implement in most applications. To address this issue a new method is proposed that requires two magnetorheological (MR) fluid dampers placed in series. With this configuration, variable damping and stiffness vibration control is simultaneous achieved by varying a small electric current to the MR dampers. This paper presents a theoretical and experimental analysis of a two degree-of-freedom system that is controlled by the MR dampers. Five different control schemes involving combinations of variable damping and variable stiffness are explored. The time and frequency responses of the two degree-of-freedom system to a random input show that combined variable damping and stiffness control provides the best vibration isolation over a frequency range spanning the system's two structural vibration modes. The experimental results agree well with the theoretical analysis.

Lateral stability control based on the roll moment distribution using a semiactive suspension

“…where W is the weight of the vehicle. Equations 10, (11), (12) and (13) indicate that K f /(K f + K r ) = 1 + e and K r /(K f + K r ) = 1 -e. By substituting equations (12) and (13) into equations (4) and (5) and introducing the notation…”

“…In addition, an SAS system with a variable stiffness and a variable damping can significantly improve the vibration control effect, but the stiffness can scarcely be controlled. Considering this scenario, Liu et al [11][12][13] proposed a new variable-stiffness variable-damping system configuration which needs adjustment of only the damping force of a variable damper. The fundamental principle of this system is the use of one or two adjustable dampers and constant coefficient springs to connect to each other in different series or in parallel to regulate the equivalent stiffness of the rig by changing the damping of the dampers.…”

Parametric and Coordinate Control of Oscillating Systems: Physics-Based Oscillation Feedback Design

“…The article [7] discusses semi-active control of vibrations and energy absorption system with periodic time-varying dampers. In [8] time-varying damping is implemented with usage of electrorheological liquids. A series of articles starting from [9] discuss stabilizing properties of pendulum systems with moving mass.…”

Sensitivity control of a MR-damper semi-active suspension

“…This paper focuses on a sensitivity control (a type of gradient approach) in a car suspension system, which can adjust the current input to the MR damper. [1][2][3][4][5][6][7][8][9][10] However the concept presented herein can be extended to other applications.…”

“…On the other hand, a MR damper applies various levels of magnetic fields to vary the viscosities of the MR fluids. [3][4][5][6][7][40][41][42][43] However, the semi-active suspension system shows worse performance than the active system because the control force can be generated only when the desired control force and the damping force act in the same direction. From this view, semi-active suspension systems are better than the fully active systems because of their low cost and competitive performance.…”