A practical and effective approach to active suspension control†

A new approach to the control of Automotive Active Suspensions driven by electrohydraulic actuators is presented. Many studies on Active Suspensions focused on implementing a desired force between sprung and unsprung masses. It is shown why the introduction of this controllable force is difficult to achieve. A novel reformulation of the Active Suspension problem, based on prescribing a given displacement between the sprung and unsprung masses, is introduced and the advantages of this approach are discussed. As a result of the reformulation, the Active Suspension problem is transformed from previously examined ‘force-tracking’ problems to a ‘displacement-tracking’ problem. Once the reformulation is accomplished, the ability for a well designed servo-control methodology to achieve the desired tracking goals is increased for the particular hardware configuration considered in this work, subject to fundamental limitations on control-plant structure. Experimental results which demonstrate the benefits of this approach are presented on a 1 degree of freedom (DOF) system. †This work is partially supported by NSF CMS99-00116. A previous version of this paper was presented at AVEC 2002.