Considerations on a Mass-Based System Representation of a Pneumatic Cylinder

Abstract

Pneumatic actuators can be advantageous over electromagnetic and hydraulic actuators in many servo motion applications. The difficulty in their practical use comes from the highly nonlinear dynamics of the actuator and control valve. Previous works have used the cylinder’s position, velocity, and internal pressure as state variables in system models. This paper replaces pressure in the state model with the mass of gas in each chamber of the cylinder, giving a better representation of the system dynamics. Under certain circumstances, the total mass of gas in the cylinder may be assumed to be constant. This allows development of a reduced-order system model.