Hysteresis Model And Displacement Compensation Technology Of Giant Magnetostrictive Displacement Actuator

Giant magnetostrictive actuator has the advantages of small size,large magnetostrictive ratio,high electro-mechanical coupling efficiency and large output force,which is a new kind of micro-displacement actuator with broad application prospect.However,the inherent hysteresis nonlinear of giant magnetostrictive materials is an important factor affecting the displacement outputting accuracy,and it is the primary problem in the application of micro-displacement actuating.In this thesis,a giant magnetostrictive actuator based on Galfenol alloy is studied,in view of whose hysteresis,hysteresis model and the inverse model are used to study the microdisplacement compensation technology.The displacement actuating features of giant magnetostrictive materials are analyzed,and a set of giant magnetostrictive micro-displacement actuating device is developed.The experiment results show that the system achieves better magnetostrictive performance under the prepressure of 12.5 MPa,which achieves maximum displacement of 25.3 μm with the excitation current of 1.0 A without displacement amplification mechanism.Aiming at the hysteresis nonlinearity of giant magnetostrictive actuator,the realization method of hysteresis model based on weight function and F-function is studied.And the experiment of output displacement prediction of giant magnetostrictive actuator is completed.The classical Preisach hysteresis model is discretized.The Preisach hysteresis model based on weight function and F-function is obtained by parameter identification and F-function calculation,respectively.The maximum displacement prediction error of the two models is 1.02 μm and 0.96 μm,respectively.And the RMSE is less than 0.68 μm and 0.70 μm.An iterative Preisach hysteresis inverse model with constant step size is implemented,whose displacement prediction module is improved to study an iterative Preisach inverse model with uniformly discrete weight function.The contrast experiment shows that the displacement compensation errors of the uniformly discrete inverse model are reduced from-3.43～2.57 μm to-1.16～0.80 μm,and the RMSE is reduced from 1.79 μm to 0.54 μm.A giant magnetostrictive displacement actuating device is built,based on which the experiment of step displacement,discrete random position,first-order hysteresis curve,sawtooth displacement,high-order loop and repeated positioning are completed by using the iterative Preisach inverse model based on the uniformly discrete weight function.Experimental results show that the maximum absolute error of displacement control is 1.93 μm,and the RMSE range is 0.53 μm～1.50 μm.