Research On Control Technology For Giant Magnetostrictive Actuator With Controllable Output Force

Because of its magnetostriction positive and inverse effect, the giant magnetostrictive material can either be used to drive or sense. With characteristics of a large magnetostriction coefficient, high energy density, low driving magnetic field, and rapid response capacity, the giant magnetostrictive material and its related devices have been extensively studied for application, especially the giant magnetostrictive actuator, which has set off a wave of research boom with the highlight of large output displacement and force, wide temperature range and low-voltage operationa.Now there have been a large number of studies on giant magnetostrictive actuator output displacement, but few studies on the output force. To meet the need of applications of output force giant magnetostrictive actuator in precision and ultra precision machining, the article made theorial and experimental research with the study object of output force for giant magnetostrictive actuator. The study established a Preisach model of giant magnetostrictive actuator output force, measured the main hysteresis loop and first order reentrant line, and obtained the table of F function for the Preisach model, then completed two experiments:first, predicting the output force of actuator under the premise of input current; second, nonlinear compensating of Preisach model, which is to seek the input current under the premise of desired output force. A non-line compensation method was put forward based on mean hysteresis line and dynamic step for Preisach model during the experiment of nonlinear compensation, and then two comparison test was made. Finally, the nonlinear compensation experiment of sinusoidal was studied.After seting up the model of output force for actuator, output force control of actuator was reseached, and output force control system component and control method was presented while the hardware and software of control system was improved. Then a PID control algorithm was designed with the feedforward compensation based on the Preisach model, and experiment was studied, which is to test the effect of achieving the target force of different control methods. As for constant control of actuator, the principle of constant force control was analyzed, and the method of combination between feed-forward compensation based on Preisach model and PID control was proposed. Its process is as follows:first use the feed-forward compensation to determine the current when actuator output force get to the target which will make the output force fast approach constant target, then obtain the constant force by variable speed integral PID control method. The experiment result showed that when the displacement disturbance was imposed on the actuator, the control system can control the actuator displacement and maintain the constant force at the target, the adjustment speed was accelarated compared with variable speed integral PID control method.The study’s results about the model and control method of the giant magnetostrictive actuator output force provide a reference for the engineering application of the actuator output force, and have a good application prospects in the field of precision and ultra precision machining such as pressure control in precision mechanical polishing which has the need for a constant output force or output force controllable, and in the field of constant cutting it also has a good prospect.