Reduction of wheel force variations with magnetorheological devices

At present, owing predominantly to advances in measurement technology and microprocessor control, development of a new generation of smart materials may lead to widespread adoption of semi-active damping systems into everyday life. An important class of such materials includes so-called intelligent'' magneto-rheological. A dominant feature of these materials is that their physical properties can be altered relatively easily under the influence of an external magnetic field. In this paper, a simplified model of a vehicle equipped with in-time controlled semi-active magneto-rheological suspension system is presented. Moreover, simple algorithms employed to control it are described and their efficacy studied by computer simulation and direct experiment. Torsional as well as reciprocating vibration magneto-rheological dampers (MRD) were used as in-time semi-active controls. In addition, a magneto-rheological rotary brake (MRB) was employed as a torsional vibration damper. As a result of direct experiments and simulations we were able to obtain characteristics of both devices showing dissipative features and relationship between model parameters. The main goal of this paper is to present methods for assessing the impact of changes in properties of MRD and MRB dampers for a reduction in variations in vertical wheel forces. These properties are controlled by demonstrated optimization algorithm responsible for an optimal selection of friction in magneto-rheological dampers. Also, an optimization criterion has been proposed. A control algorithm presented in this paper has been verified by means of conducting an extensive experimental investigation employing a Ford Transit van. Based on the results of our numerical and experimental studies it has been proved that through properties changes in MRD and MRB dampers it had been possible to reduce the variations in vertical wheel forces. Thus, an increase in the safety of the vehicle is possible.