Research On Precision Positioning And Control Of Giant Magnetostrictive Actuator

Rare-earth Giant Magnetostrictive Material (GMM) has magnetostrictive effect, that is the size of GMM will extend significantly when magnetization state changes. With the advantages of large force, high resolution and quick response, etc, GMM is considered to be helpful to improve the technology of control, the accuracy of positioning products and the response speed of system.A kind of Giant Magnetostrictive Actuator(GMA) is designed in the dissertation which can be used for precision drive and precision positioning. GMA owns the advantages of high accuracy of positioning, quick response, large force, etc, which lead to a promising prospect of application. However, the inherent nonlinear hysteresis, drift and creep pose great challenges for practical application of GMA.The characteristics and properties are discussed based on the microstructure of GMM. Moreover, the magnetic origin, magnetostrictive process and the formation of hysteresis are introduced based on the ferromagnetic theory. The nonlinear modeling method of GMA is discussed as well.A magnetostrictive precision micro-displacement actuator prototype is successfully developed and the structure and working principle are presented. Linear dynamic model of GMA system including controllable power is established on current controlling model. Besides, the controllable power and inductance are integrated with experimental techniques when modeling of time-delay in GMA system. The relationship between dynamic performance and the design parameters of GMA is studied based on Matlab. Also the PID controller applicable to GMA is designed combining similation and experimental test.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 for the purposes of saving I/O resources and the integrated zoom function.Iterative linear compensation and feedforawrd compensation based on Preisach inverse model are studied focus on the accuracy and the efficiency of these two strategies. For higher efficiency of iterative, a new nonlinear adaptive compensation algorithm is presented to accelerate the convergence speed which is the weakness in conventional comensation control of Giant Magnetostrictive Actuator. Steady-state error is taken as one reference input when solving the inverse of Preisach model. Contrastive experiments reveal that new iterative algorithm presented has high precision of position control as well as faster convergence speed comparing with conventional feedforward compensation control.