Abstract: The pressure models of squeeze gas film based on hydrodynamic lubricating theory are established, the dynamic equation of freedom levitating object on the squeeze gas film is presented too. And then the non-linear equations are solved by numerical methods, and the pressure distribution and load capacity of squeeze film are obtained. On this basis, a study of levitating precision is performed, the major factors which influence levitating precision are discussed, it is found that the squeeze film levitation could reach high position precision, the main factors influencing the levitation precision include exciting frequency, exciting amplitude and the suspended mass etc. In addition, an experiment about the levitating precision is carried out, it is shown that there exist some differences between the theoretical results and experimental data. The main reasons causing the difference are constraint of the motion in the horizontal plane is difficult, the exciting signals is not single and the theoretical model is not very perfect. The conclusions could be used in the design of near field levitation devices.

Key words: near field ultrasonic levitation;gas squeeze film;suspending displacement;levitating precision