Experimental Study of Double-Acting Pneumatic Cylinder

Abstract

AbstractIn this article, the dynamics of a double-acting pneumatic actuator was experimentally studied. To understand the details of dynamics and provide experimental data for further modeling and numerical simulation of actuators, a special test bench was designed. The bench includes a high-resolution linear encoder as well as a dSPACE 1104 data acquisition board, that permits high-frequency sampling to identify important features in the measured data at different source pressures; it also incorporates two pressure sensors, a solenoid valve, a push button, and a measuring interface to automate the acquisition of data. High precision measurements of the time of displacement and position of the moving elements, piston rod or cylinder body, allowed us to calculate velocity and acceleration. We found that the velocity of the moving element is near constant in a major part of the stroke. The recording of the dynamics of upstream and downstream pressures in the pneumatic cylinder chambers at different source pressure levels permitted us to calculate the force exerting by the piston and to explain the kinematics of the moving element. The matching of the upstream and downstream pressure plots with the displacement of the moving element allowed us to establish the instant when the moving starts, and this way evaluates such an important feature as the static friction force between the piston and cylinder body. Various scenarios were used in the experiments, including the fixing of the piston rod, which allow the cylinder body to move or vice versa, the horizontal or vertical position of the pneumatic cylinder and the forward or backward stroke movement. The results obtained with the proposed experimental bench provide essential information on the dynamics of a double-acting pneumatic cylinder that can be included in the mathematical model of the cylinder and used in mobile robotics.