Research On Differentially Driven Giant Magnetostrictive Micro-displacement Control System Based On Dynamic Preisach Model

The suppression and isolation of vibration from external environment and the devices is always an important research topic in the field of ultra-precision machining, ultra precision measurement and aerospace equipment. The common means contain passive, semi-active and active vibration isolation. Giant magnetostrictive material has high energy density, scalable coefficient(10-3), short response time, great output stress and low driving voltage. Therefore, actuators driven by this material can be used in an active vibration isolation system. The main purpose of this paper is to optimize the mechanical structure and driving method of the original actuator in the project, as well as the control system, so as to improve the dynamic output performance of the whole system.The main contents include the following three parts. In the first part, shortcomings of the original giant magnetostrictive actuator(GMA) are analyzed, the driving magnetic field structure and the mechanical structure of it are optimized and a new design of a differential GMA, which is combined by two conventional GMAs, is given. In the second part, the dynamic model of the differential GMA is deduced based on the analysis of the original GMA. What’s more, affect to the output of the change in load equivalent stiffness and weight is analyzed through simulation, and the influence is discussed when the parameters of the two constituent GMAs are different. In the third part, a dynamic Preisach model is introduced, simulation of the displacement feedback PID control and displacement feedforward-feedback compound control is given. A control system which contains a differential GMA, a capacitive displacement sensor, a power amplifier, a PC and a PXI-8102 acquisition board, is built, and then both the static and the dynamic performance of the system are tested.Experimental results show that the giant magnetostrictive micro-positioning system has a resolution of 6nm within the range of 18.5μm. Its response time of unit step incentive reaches 5ms. In the compound control mode, it can achieve a lagless sine displacement output within the frequency if 200 Hz and amplitude of 3μm, and the maximum error is 0.6μm. The maximum load of the system is 725 g.