Some Considerations on Characteristics of Pneumatic Servomechanism

It is well known that the pneumatic-hydraulic control system can improve the incomplete points of hydraulic system in automatic contour-following machines. However, the characteristics of a pneumatic servomechanism is susceptible to influences of various frictions, owing to its small operational force. In this paper, the effects of the viscous friction in the pipe and the solid friction of the output element are examined theoretically and experimentally. The critical solid friction that does not have a harmful influence upon the dynamic characteristics of the pneumatic servomechanism is introduced as a function of the properties of the pneumatic mechanism and working conditions. On the basis of these results, the concrete and practical means for improvement of the characteristics of a pneumatic servomechanism are discussed.