Electromechanical network modeling applied to magnetoelastic gyro sensor design

Electromechanical network models are used in this paper to analyze a prototype micro-gyro sensor that employs the magnetostrictive alloy GalFeNOL for transduction of Coriolis induced forces into an electrical output at a given angular velocity. The sensor is designed as a tuning fork structure which reacts with vibration of the prongs in tangential direction due to an excited vibration in radial direction. A GalFeNOL patch attached to the axial-radial-surface changes its permeability depending on the bending. When it is surrounded by a solenoid coil and a magnet creates a bias magnetic field in the sensor patch, then this field fluctuates with the prong vibration. The induced voltage in the sensor coil is used as sensor output. A sinusoidal angular velocity being effective on the tuning fork structure causes an amplitude modulation of the excitation frequency which is the carrier frequency. A circuit representation of the electromechanical system is derived where the prongs are modeled as dynamic bending beams. The network model enables an understanding and explanation of the behavior of this system involving different physical domains, as well as fast analytical and numerical calculations, e.g. with pSpice. Experiments confirm the predicted sidebands of the sinusoidal rotation.