Dynamic and stability analysis of an air pad controlled by a differential diaphragm valve

The use of pneumatic valves is a simple and economical way to significantly increase the static stiffness of aerostatic pads. The design procedure of this kind of components consists, firstly, in the optimization of the static performance and, secondly, in a dynamic analysis to assess the stability of the system. This article theoretically analyzes the dynamic behaviour of an aerostatic pad controlled by a custom-built differential diaphragm valve. The stability analysis is performed by means of a lumped parameter model. The equations have been linearized and the bearing stiffness and damping have been investigated using the perturbation method. Subsequently, the paper proposes some functions for verifying the stability of the controlled air pad through Routh-Hurwitz criterion.