| With the rapid development of automobile,aerospace,machine tool processing and light industry,the requirements for parts are becoming higher and higher.In order to meet the performance requirements of production and application,the requirements of machining accuracy of parts are also increasing.In some parts of the processing methods,turning technology is a processing method which can achieve high efficiency and precision.Its core is a giant magnetostrictive actuator(GMA)made of giant magnetostrictive material(GMM)represented by Terfenol-D.The system has the advantages of simple structure,no gap and high stability.It can not only realize high-precision machining,but also overcome the shortcomings of traditional methods.At the same time,it can also be applied to the processing of complex parts.However,GMA is made of rare earth giant magnetostrictive material,and it has hysteresis characteristics.At the same time,the design and application of GMA involve many subjects: automatic control theory,nonlinear vibration,electromagnetism,machining,etc.The complex characteristics will cause the displacement accuracy of GMA control is not high,which will affect the development of GMA.Therefore,the research of GMA control system is particularly important.In order to solve the above problems,GMA of turning system is selected as the research object in this paper:1.The development history,effect and working mechanism of giant magnetostrictive materials are introduced,and then the related industrial applications are introduced.According to the nonlinear characteristics of the actuator,combined with the research status of hysteresis model and control method,JA model is selected to describe the hysteresis model,and the control method combining sliding mode control and intelligent control is used to realize the precise control of GMA.2.According to the theory of piezomagnetism,considering the influence of temperature change and hysteresis nonlinearity,on the basis of JA model,the models of GMA external excitation current and driving magnetic field,hysteresis model of excitation magnetic field and magnetization magnetic field,magnetization magnetic field and strain are established.Finally,a complete GMA dynamic model is obtained.Then the dynamic model is discussed in detail by using MATLAB simulation tool,and the influence of different parameters on the model is obtained.3.By introducing turning force,the dynamic model of GMA turning system is established on the basis of GMA dynamic model.Considering the hysteresis characteristics of GMA,the sliding mode variable structure control method independent of system parameters and disturbances is used to realize precise control of GMA.Firstly,the sliding mode control method based on reaching rate is used to obtain low steady-state error,but the chattering phenomenon of the system is obvious.Then,the robust global fast sliding mode control is adopted to reduce the chattering phenomenon.4.Aiming at the disturbance upper bound of uncertain value in GMA model,RBF neural network which can be approximated with any precision is adopted,and the sliding mode control method is combined to realize the adaptive learning of the upper bound of the disturbance and further reduce the chattering phenomenon.Then an adaptive fuzzy sliding mode control method based on linearization feedback is proposed.The fuzzy system is used to approximate the unknown parameters.In order to reduce the chattering,the continuous function is used to replace the symbolic function.The simulation results show that the control method combining sliding mode control and intelligent control not only makes the system have better control accuracy,but also reduces chattering phenomenon and improves the stability of the system.Figure 29 table 3 reference 73... |
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