Experimental identification of a pneumatic valve-cylinder system for attitude control

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). A prototype of an active suspension system of the operator seat has been developed in the laboratories of INAIL. The prototype can be configured with hydraulic or pneumatic actuation. This paper focuses on the pneumatic solution powered by a proportional pressure control electro-valve. Since several proportional pressure control valves are commercially available, three of them have been experimentally tested to determine the most suitable one for control purposes. Numerical modeling of the three valves has been carried out and described. Experimental tests on the selected valves allow for identifying the main dynamic parameters of the numerical models, providing a reliable simulator to be adopted for the development and optimization of the control system. The performances of the valves are compared and discussed.