The Synchronization Research Of Four Cylinder In Pneumatic Servo Proportional System

Compared with the hydraulic system,the driving force of the pneumatic servo system is smaller than that of the hydraulic system,in the same mass and volume of the driving system.Therefore,it is a common solution to complete an action drive a plurality of pneumatic actuators together,in the pneumatic drive system.However,due to the inherent strong nonlinearity,the time-varying parameters and the uncertainty of the model of the pneumatic system,the synchronous motion of the system of a multiple pneumatic cylinders can not be guaranteed,which leads to the stagnation of the moving parts and even damage to the mechanical part.Based on this problem,the topic of synchronous motion in the pneumatic servo system with multiple pneumatic cylinders was presented,based on the research background of the lifting system with four pneumatic cylinders in the polyurethane curing drying and cooling equipment.The establishment of the mathematic model of a pneumatic servo system with single degree,contains the differential equation of gas state,the gas flow equation which describes the state when gas flow throw the pneumatic proportional valve orifice and the equation of motion of a cylinder piston.Based on the analysis of the motion characteristics of the pneumatic proportional servo system,we established the nonlinear mathematical model of the pneumatic servo system with single degree,and the numerical simulation experiments in MATLAB/SIMULINK proved that the mathematical model of the pneumatic servo system was reasonable and effective.It is necessary to carry on the accurate linearization to the research object due to the difficulty during the design of controller caused by the severe nonlinearity.And we established the differential equation with 3 degrees which described the motion characteristics of the sealing device in the polyurethane curing drying and cooling equipment.At last,we analyzed the redundancy of the research object,and the control allocation problem was presented.We established the double closed loop control system that pressure control based on the direct method of Lyapunov in the inner loop and the Sliding Mode Variable Structure Control with robustness.The numerical simulation of MATLAB/SIMULINK was carried out and the simulation results are analyzed in detail.This study shows that it can ensure the sealing device maintaining a good horizontal posture under the vertical interfering resistance and the interfering torque which rotate the two horizontal axes,under the control of the double closed loop control system.