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Shock and Vibration
Volume 10 (2003), Issue 1, Pages 59-69

A Hybrid Control Policy for Semi-Active Vehicle Suspensions

Fernando D. Goncalves and Mehdi Ahmadian

Advanced Vehicle Dynamics Laboratory, Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, USA

Received 25 April 2002; Revised 23 May 2002

Copyright © 2003 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Various control policies, such as skyhook and groundhook control, have often been considered for semi-active vehicle suspensions. Past studies have shown the performance limitations of these policies, as well as others that have been considered for vehicle applications. This study will provide a look into an alternative control technique called "hybrid control", which attempts to merge the performance benefits of skyhook and groundhook control. The results of this study are based on an experimental evaluation of hybrid control using a quarter-car rig and a magneto-rheological damper. The control policy is employed and evaluated under a steady-state or pure tone input, and a transient or step input. Peak-to-peak displacement and peak-to-peak acceleration are used to evaluate performance. The results indicate that hybrid control can offer benefits to both the sprung mass and the unsprung mass. The steady-state results reveal that hybrid control can be used to reduce the peak-to- peak displacements and accelerations of both bodies. The transient evaluation shows that hybrid control can be effective at reducing the peak-to-peak displacement of the sprung mass.