Research On Giant Magnetostrictive Micro-displacement Control System Based On External Force

One major effect in ultra-precision process is environmental vibration, whichlimits the accuracy of test instruments and machining equipment. Effective methods canbe achieved by active and passive vibration isolation, reducing the environmentalimpact of vibration on the accuracy of the instrument. The excellent advantages of giantmagnetostrictive actuator, such as large magnetostrictive rate, fast response, highprecision, low drive voltage, etc, make it suitable for active damping system. Active andpassive isolation system constructed by giant magnetostrictive actuator and flotationtechnology, can not only isolate low-frequency vibration from environment, but alsoweaken high amplitude and high frequency reverse disturbance caused by load in themachining process. The main purpose of this paper is to study the giantmagnetostrictive micro-positioning system, build experimental platforms to meet therequest of the ultra-precision positioning, and achieve self-sensing for disturbance ofdynamic load.The main contents include the following three parts：The first part studies theproperties and mechanism of the giant magnetostrictive material, measures the cure ofoutput displacement, identifies the parameter of the system and establishes Preisachnonlinear model between input and output to predict the output accurately. Next, whenexternal force applies on the output rail of the magnetostrictive actuator, self-sensingvoltage can be measured in dynamic through the decoupling boards, and the theorycurve of the external force can be computed, which is based on the principle of Villarieffect, then the perception sensitivity and maximum error value are derived throughcomparing the theory curve with the actual curve measured by metric force sensor.Finally, along with the establishment of the Preisach model, the simulation can beaccomplished, and then a platform is established consisting of Giant MagnetostrictiveActuator, capacitive displacement sensor, NI PXI-8102data acquisition system and acomputer, based on which the open-loop performance, the feed-forward performanceand the closed-loop performance are tested respectively. With all the above parts, thegiant magnetostrictive actuator system based on external force self-sensing is achieved.Experimental results show that the resolution of the giant magnetostrictivemicro-positioning system is up to10nm, with the response time of unit stepincentive reaching10ms, and the frequency of sine incentive can response no lessthan500Hz. In the condition with pre-stress of10N and bias-magnetic of24mT, theself-sensing sensitivity of external forces perform between0.072N/(mV·s)~0.075N/(mV· s), which means the measuring uncertainty is4.08%. In conclusion,excellent static and dynamic characteristics of positioning has been performed in the ultra-precision micro-displacement system, and the measurement with highsensitivity of force self-sensing is achieved, which means that the self-perceptioncan be applied to the closed-loop control system to improve the performance ofultra-precision positioning system.