Passive, semi-active and active dampers have been used to dissipate energy in mechanical systems. Semi-active dampers have higher performance than passive dampers and require less power to operate than active dampers. Its damping characteristics can be changed properly for varying conditions. In this paper, we consider the semi-active damper using Magnetorheological(MR) fluid. MR fluid has a variable damping characteristics by the magnetic field intensity. It has several advantages such as high strength, low viscosity, robustness in impurities and wide temperature range of stability. We designed a constrained rotary MR damper based on the valve mode which can dissipate the most energy per unit volume among the existing modes. The system modeling which is developed by adopting Bingham characteristics is obtained from the experiment.
As a possible application of MR damper, tracking control of a pneumatic servo system which has merits such as large power output, rapid response and simple structure, is performed by the simple on-off control and PID control for ramp and sinusoidal projectories.
Generally it is known that MR Fluids have a Bingham characteristics, but we found out the hysteresis characteristics which is quite significant. We proposed the causes of the hysteresis characteristics in qualitative analysis and the possible improvement scheme to reduce the nonlinear characteristics, i.e., the hysteresis characteristics is suggested.
