New Mathematical Modeling of Servo-Pneumatic Systems,Using Sliding Mode Logic for Force-Position Control

In this work, a new mathematical modeling of servo-pneumatic system's dynamics is presented. In this new modeling, internal forces, such as friction and external forces acting on the moving rod of actuator, such as loads or disturbances, are mathematically modeled with their appropriate logic. First, pressure distribution on two sides of moving piston is assigned to cancel out the friction force with respect to the piston velocity sense and to balance the external forces according to their acting direction. The regulation of pressure continues to provide the desired acceleration in the piston. The model of pressure valves is assumed linear. Due to the entrance of non-linear terms into the equations describing dynamics of the system, mathematical modeling is based on sliding mode logic. Also, sliding mode control algorithm is used to achieve the positioning aim. Finally, a numerical simulation is done to show the performance of the control activity in the presence of the new mathematical modeling.