Design for a novel MRF semi active damper and certification of the nonlinear controller's effects

This paper deals with a novel type of semi active damper, which is composed of a cylinder injected with Magnetic Rheological Fluid (MRF) and an electromagnet with a nonlinear H/spl infin/ controller. It is generally known that the viscosity of MRF can be changed by the magnitude of a magnetic field. Therefore, this study aims at constructing such a semi active damper system that makes good use of the property. A flow for controlling the semi active damper system is as follows. First, if an electromagnet current is changed, the magnitude of the magnetic field generated by the current is changed. Next, the viscosity of MRF is also changed by the magnetic field. Thus, the motion of a piston set under the MRF is controlled. As these results, an overall equivalent damping coefficient in the semi active damper system can be controlled by the electromagnet current. Thus a semi active damper is made and its properties are measured. In addition, a suitable nonlinear compensator for the MRF damper is installed, various vibration experiments are carried out and many interesting results are reported.