Research On Position Control Method Of Pneumatic System Of Palletizer

The palletizing machine is widely used in the palletizing of fly ash brick.With the development of brick-making industry and technology,the application of palletizing machine is more and more widely,and manufacturers' requirements of palletizing machine's efficiency and positioning accuracy are also improved.Compressed air as working medium of the pneumatic system,and the pneumatic positioning servo control system is used to realizing an accurate positioning of the vertical lift circuit,which is the most critical part of the system.But the control precision of pneumatic palletizing machine is not high enough,and its operational stability is poor,which easily result in jitter or temporal fluctuation,and get the object fall and damage.At the same time,because of the compressibility of air,the system is slow in respond speed.In this thesis,the independent load port control technology is used to improve the pneumatic positioning servo control system of vertical lift loop,which is the most critical part of palletizer.The compound control of the two chambers is based on the displacement closed loop and the pressure closed loop.Reducing the change in pressure of the system by balancing the vertical gravity load,thereby improving the stability of the cylinder.In order to further improve the response speed and positioning accuracy of the pneumatic system of the vertical lift loop,a new control strategy,which combining the improved conjugate gradient BP neural network PID control algorithm and the classical PID control method is proposed in this thesis.Based on AMESim and Matlab/Simulink simulation software,a series of simulation models are built.The improved conjugate gradient BP neural network PID control algorithm is realized by writing S-function,and it is applied to the positioning control of the pneumatic system,the simulation analysis is carried out.In the pneumatic positioning servo control system,the complex friction characteristic of the cylinder is the most important factor,which can affect the performance and the positioning accuracy of system.In this thesis,the new extended Lu Gre friction model is used to designing the friction state observer.The static and dynamic friction parametersare identified by experiments,and after that,there is an on-line friction compensation experiment.Finally,to verify the feasibility of the pneumatic positioning servo control system and the control strategy,a series of simulation experiments are designed based on the experimental bed.The experimental results show that the control precision of the improved system is high enough,and it can meet the needs of engineering application.