Research On Magnetic Microdrive Method Based On Inverse Magnetostrictive Effect

Precision machining, as the basis of developing advanced technology, is also an important sign of a nation's scientific and technological level. And precision micro-drive technology is the key to achieve precision machining. Compared with piezoelectric actuator, Giant Magnetostrictive Actuator (GMA) has large output displacement, large output force, fast response, high-resolution displacement and low drive voltage. So it has broad application prospects in the fields of micro-drive, precision positioning and noise damping. This dissertation emphasizes on axial moving type GMA, developed a magnetostrictive precision micro-displacement actuator prototype in order to achieve self-sensing function. By designing the structure of water cooling system we made it smaller and improved it's output performance; As the GMA has a good micro-drive characteristics performance under constant force while a serious nonlinear under the condition of variable force, this article makes exploration research on self-sensing GMA based on inverse magnetic effect. It proposes a method of separating the disturbance of changing force and does corresponding experiments. The research can improve the GMA output performance and promote its application.Starting from the principle of magnetostriction, this paper finds the cause of GMA nonlinear output, and analyzes on the relationship of strain stress, magnetic field strength, magnetic induction and temperature. The designed experimental platform consists of the main actuator, water cooling system, magnetic induction and temperatures sensing circuit, induced signal separated circuit, main control circuit based on DSP and data-processing system based on LabView.Then, this paper made research on separated methods of self-sensing signal which caused by disturbance force, including bridge circuit, adding testing coil, establishment of state observer. On the basis of Piezomagnetic Equation, deduced the relationship of output force, output speed and sensing signal on different working boundary conditions. They are the theory basis of data-processing system. In theory the self-sensing signal is proportional to the velocity by bridge circuit while proportional to the load force by state observer. Finally, this paper completed the experimental analysis on designed self-sensing GMA. The temperature and magnetic induction sensing circuit can meet the requirements of accuracy; The magnetic field uniformity has been improved by lowering the maximum attenuation to 4.95%; The water cooling system can keep GMA work within 0.2 degrees Celsius; On small current-driven, actuator output displacement in a fixed position creep can keep 20nm or less; Driving in the same current, the output displacement is twice as large as the Original prototype and the lift curve linearity is better; The output displacement's repeatability errors of it is less than 100nm; Through the stepping drive current, the step output displacement is controlled less than 50nm. Based on the above good output performance, the self-perception function of force is realized in the constant drive current with the method of monitoring magnetic field. In contrast with the standard force sensor, the maximum error in the dynamic force range of 200N is less than 20N.