Research On Precision Positioning Of GMA Based On Prandtl-Ishlinskii Modeling

The development and application of the technology of precision engineering in many fields promotes the development of the precision positioning technology. As a part of the precision positioning system, the design of the micro-displacement actuator is very important. Giant Magnetostrictive Material(GMM) is a suitable material to produce micro-displacement actuator as it has the advantage of large load capacity, rapider response , higher power density and higher reliability, etc, And Giant Magnetostrictive Actuator(GMA)which is made of GMM has a promising prospect in precision positioning. However, the inherent nonlinear hysteresis poses great challenges for practical application of GMA.This thesis takes the precision positioning technology as the background, and summarizes the significance of micro-actuators applied in the field of hyper-precision machining. Magnetostrictive phenomenon and its reasons, the properties of GMM and its applications in micro-actuators are depicted, which is the necessary basis in the research and application of GMA.A magnetostrictive precision micro-displacement actuator prototype is successfully developed and the structure and working principle are presented. According to the disadvantage of the hysteresis theory model of GMA, improved model of Prandtl-Ishlinskii is raised. Based on experimental data, the hysteresis model related to stress of GMA and its inversed hysteresis model have been established.The measuring and controlling system for GMA is established based on the single-chip W78E058B. Moreover, the input and output channels are designed to match the accuracy of driving and measuring parts. I~2C bus is taken instead of parallel bus in design of keyboard circuit.Through the displacement tracking control experiments of GMA, Proportion iterative compensation and Proportion whit feedforawrd compensation based on improved model of Prandtl-Ishlinskii inverse model are studied focus on the accuracy and the efficiency of these two strategies. Contrastive experiments reveal that the displacement has been quickly tracked by using proportion whit feedforawrd compensation based on improved model of Prandtl-Ishlinskii inverse model, and tracking curve was gentle. At the same time, this iterative algorithm has high precision of position control as well as faster convergence speed.