Experimental testing and control of an ER long-stroke vibration damper

The potential of smart fluids (both electrorheological (ER), and magnetorheological (MR)) in damping devices is now well-known. Whilst both types of fluid can suffer from drawbacks such as sedimentation, fluid degradation, and problems with containment or sealing, these issues are not insurmountable and solutions have been engineered such that practical damping devices are now commercially available. However, one drawback is that the force-velocity characteristics of a smart fluid device are inherently non-linear, possessing the general form associated with a Bingham plastic. This means that while practical devices have the potential to modify rapidly their behavior, it can be difficult automatically to adjust the device's response. For example, much research has focused more complex closed loop control strategies such as neural networks, H-infinity and sliding mode controllers. This is in contrast to research at the University of Sheffield, where it has been shown that proportional closed-loop control can provide an elegant means of linearising the device's behavior. More recent work has demonstrated that this control strategy can be used to perform arbitrary shaping of the device's force-velocity characteristic. In the present contribution the authors will demonstrate by simulation the practical significance of this phenomena, using the classical mass-isolator problem as an example.