Model-free Adaptive Control Of Pneumatic Variable Load Loading Systems

Pneumatic loading technology is an industrial technology with low cost,light weight,no pollution and strong practicability.It takes compressed air as the working medium,carries on the energy conversion and the control,realizes the mechanization production manufacture,has been widely used in the world scope.However,due to the strong nonlinearity,strong coupling and time delay of pneumatic loading system,the modeling and controller design of pneumatic loading system are very difficult.This paper will take the pressure tracking control of pneumatic variable load loading testing machine as the research topic,on the basis of analyzing the working principle of the system,establish a mathematical model close to the actual system,and design a controller with simple structure,easy realization and strong anti-interference for the purpose of practical application to complete the pressure tracking control of pneumatic loading system.Specific research contents are as follows:Firstly,based on the analysis of the research status of the pneumatic loading control system at home and abroad,the working principle and structure composition of the pneumatic variable load loading testing machine are given.Through the written monitoring software of the upper computer,the real-time signal processing of various test data can be realized.On the basis of the reasonable hypothesis,a mathematical model close to the actual system is established for the subsequent controller design and simulation research.Secondly,a model-free adaptive controller is proposed by analyzing the shortcomings of the previous control strategies of pneumatic systems.This kind of controller has the advantages of simple structure,few parameters and no mathematical model of controlled system.It is a low-cost controller.Then,under the action of three typical input signals,the simulation is compared with the classical PID control method,and the test is verified on the pneumatic variable load test machine.The simulation and test results show that the model-free adaptive controller has very strong adaptability and robustness,and is easy to realize in engineering.Finally,considering the bounded external disturbance in the practical application of the pneumatic loading system,the tracking differentiator was added to the model-free adaptive control as a feedback filter to enhance the system’s anti-interference.Combined with the advantages of the two methods,the influence of external interference on the system can be effectively suppressed and the robustness of the control system can be improved.In the aerodynamic load changing load test machine to test,and with no model adaptive control,since the immunity control is compared,the test results show that the improved controller is featured by strong anti-interference,fast response and strong robustness characteristics,very suitable for pneumatic variable load loading this time delay,time varying and strong coupling system.