Pneumatic Micrometer with a Feedback Circuit

This paper is concerned with transfer characteristics of a pneumatic micrometer system with a negative feedback transducer. The system has two negative feedback pathes. One of them is based on the transfer characteristics of the feedback transducer which is introduced to linealize the transfer characteristic of the system and the other is caused by repulsive pressure force between nozzle and its counter face as an inevitable consequence of introducing the former. The feedback quantity through the latter is non-linear in relation to the output pressure but linear to the stiffness of the transducer. The total static transfer characteristic is shown as the sum of the transfer characteristics of the above two feedback circuits and of the basic pneumatic micrometer. The condition of reducing the above secondery feedback effect is discussed. Using a deviation ratio, defined by representing the transfer characteristic curve of the basic pneumatic micrometer circuit as a sum of an appropriate linear relation and the deviation from it, the linear range on the transfer characteristic curve of the system can be estimated from the feedback ratio of the feedback transducer, so far as the secondary feedback effect is small. The dynamic performance and an application of the principle are also described.