Reduction of vibrations by bang-bang controlled electrorheological dampers

This article is concerned with the application of electrorheological fluids (ERF) to the reduction of vibrations by controlled damping. Many papers de al with mechanical characteristics of ERF, but only a few articles have bee n published about the technical applications of these fluids, although grea t expectations have been placed into it some years ago. Vibration reduction by damping control is a difficult task because forces can only be generate d when relative velocities exist between both ends of the damper. The desig n of a control strategy cannot be investigated by the methods of linear con trol theory. It is a task for the dynamic programming. The main objective o f this paper is to present different methods for the investigation of suita ble control strategies, and to verify the theoretical results by simulation and experiments. By simulation, it can be shown that the bang-bang control of damping - that means switching between the highest and the lowest possi ble damping - is an efficient way for the reduction of vibrations in specia l systems. Nearly no additional Fewer is necessary. This switching can be r ealised with controlled valves and bypasses or by the ERF. Experiments with the ERF prove the theoretical considerations; still, there are several sid e effects making it difficult to perform a useful experiment, for example, leakage in the damper or electric isolation problems or the dependence on w hether the AC or the DC is used.