Modelling and control of a full vehicle active suspension system

Abstract

The work is devoted to the modelling and control of a wheeled vehicle active suspension driven by electrohydraulic actuators. A full suspension model of a SUV type wheeled vehicle was proposed by the authors. In order to formulate the control law of the vehicle suspension, it was necessary to include in the model all elements which have an influence on its dynamic properties. Vertical vibrations as well as pitch and roll was taken into account. In modelling of lateral swaying, torsion bars have been taken into account which are of great importance. For the construction of the active suspension of the wheeled vehicle, the authors used hydraulic cylinders controlled by proportional pressure valves. As a master controller, an optimal control with a quadratic quality indicator was used. Each of the strut suspensions has been equipped with a direct controller whose purpose was to reduce vertical vibrations. Longitudinal and lateral vibrations are reduced by the use of a master controller. Thanks to the use this type of control, it was possible to formulate a quality indicator which takes into account both driving comfort and good vehicle handling. The literature review shows that research of the active suspension control is generally carried out on models reduced to a quarter of a vehicle suspension. The original, 7DOF model of SUV suspension and dynamics equations describing the actuators - which enabled the synthesis of control for the real object - were used in this work.