Research on self-sensing technique of giant magnetostrictive actuator for seawater hydraulic servo valve

In order to realize the closed loop control of diphase oppositing giant magnetostrictive hydraulic servo salve without the independent displacement sensor, the output displacement of the actuator was detected by measuring the change of the driver coil voltage drop, based on the characteristic that the magnetic permeability of magnetostrictive material changes under external load (inverse magnetostriction). A magnetic model which can describe the dynamic properties of the material was established. According to the model, a new self-sensing technique in which the driver function and the sensor function shared the same coil was presented. A self-sensing circuit was designed and the principle was analyzed. Experimental studies showed that the designed circuit can successfully detect the displacement of the actuator with good dynamic characteristics.