Hysteresis Modeling Of Giant Magnetostrictive Actuator And Control Technology

Giant Magnetostrictive Actuator (GMA) is a kind of micro-displacement actuator whose actuation component is a novel functional material - Giant Magnetostrictive Material (GMM). With the advantages of large displacement, high force, rapid response, wide range of temperatures and low voltage operation, it is applied in precise and ultra-precise machining, liquid control mechanics, micro-adjusting and compensation mechanics, MEMS, nano-technologies, etc. However, GMM is ferromagnetic material. The inherent hysteresis in such material and other components of the driving magnetic circuit leads to strong hysteresis, poor repeatability, and severe nonlinearity in GMA's displacement, which restrict the positioning precision of GMA and hamper its wider applications in many fields.Based on deep studies of the modeling and control technologies of GMA's hysteresis nonlinearity, a novel hysteresis model of GMA is put forward according to Preisach theory. The inverse model of GMA is deduced and a feed-forward controller is designed to compensate the hysteresis nonlinearity. On the basis of feed-forward control, an adaptive controller and its algorithms are also designed, according to the deviation signal of set value and real output of GMA, to take full advantages of feed-forward and feedback control and to make GMA more precise.The close-loop control system of GMA is designed and implemented, including the constant-current source, sensor and its transmitter, microprocessor and its peripheral circuits, and the control and drive software of the system. On this basis, the step responses and the tracking curves of the feed-forward and feedback control schemes are measured. The experimental results verify that the hysteresis model of GMA describes the hysteresis nonlinearity exactly and the two control schemes compensate the hysteresis nonlinearity to a great extent. Thus the control precision of GMA is largely improved.At the last part of this paper, a summary of the main contents and the suggestion of the probable further research work are given.