Multi-physics modeling of an active seat suspension with pneumatic or hydraulic actuation

Vertical vibrations on agricultural tractors, due to soil irregularities, represent a major cause of diseases of agricultural operators. The control of noise and vibration on the operator is of interest to the (Italian) National Institute for Insurance against Accidents at Work (INAIL). Several systems for the seat or cabin suspension are commercially available to reduce the transmitted vibrations. The state of the art of suspension systems includes passive, semi-active and active solutions. A prototype of an active suspension system of the operator seat has been developed in the laboratories of INAIL. The prototype has the peculiarity that it can be configured with hydraulic or pneumatic actuation. In order to develop and optimize the control system, multi-physics modeling of both configurations has been carried out and described in this paper. The hydraulic and pneumatic circuits as well as the two types of valves and the actuators are numerically modeled in the Simulink environment. The proposed models have been validated using experimental data.