Position Control with Pneumatic Piston and Microprocessor

Abstract To realize a high level of positioning accuracy, experimental investigations are carried out with pneumatic cylinders of 5 cm diameter and 5 cm stroke. The piston rings are replaced by O-rings, and the contact forces are adjusted. A level of accuracy higher than 10 µm was obtained relative to the set value of desired position, by a combination of time controlled continuous displacement and sequential step motion. The process is regulated by a microprocessor combined with a linear encoder of 1 µm resolution. An analogue feedback system can control the piston more rapidly within 20 µm in the best condition. The combination of position and velocity feedbacks is effective to the accurate position control.