Stability and Positioning Accuracy of a Pneumatic On-Off Servomechanism

The development of a low cost and simple, pneumatic positioning system is described, which utilizes a solenoid-operated on-off servo controller. The design utilizes an electronic relay and a solenoid valve, and position and velocity feedback are incorporated with the relay to form a closed loop system. Since stability and accuracy are of vital importance for this type of servo-mechanism, two implementation methods are considered to improve such characteristics: 1. stabilizing tank; 2. cylinder orifice. To evaluate the effectiveness of these methods some experiments were carried out with a pneumatic prototype. The effects of cylinder orifice, stabilizing tank and velocity feedback on the positioning accuracy are discussed in some detail.