Research On Acceleration Measurement System Based On Tunnel Magneto-Resistance Effect

The acceleration measurement system is a device for sensing and measuring the ac-celeration signal in the inertial space.It is widely used in the fields of inertial navigation system,automotive electronics,intelligent control,gravity field test and seismic detection.Therefore,the research of acceleration measurement system has important practical signif-icance and application prospects,which is also one of the current research hotspots.With the development of micro-nano processing technology and new materials re-search,a highly-sensitive tunnel magneto-resistance(TMR)sensor has emerged.The way to achieve high-precision acceleration measurement with the highly-sensitive TMR is worth studying.Based on the full research of the TMR principle and acceleration meas-urement technology,an acceleration measurement system based on TMR effect is proposed in this paper.Based on the TMR effect,the acceleration signal can be measured by constructing the"force-magnetic-electric" coupling structure.In terms of the force-field coupling,the mi-cro-cantilever structure is used to realize the conversion from input acceleration to me-chanical displacement.In terms of the magnetic field coupling,the position of the magnet-ic field source attached to the free end of the micro-cantilever changes,which results in the linear conversion from displacement to the change of the magnetic field distribution.In terms of the electric field coupling,the change of magnetic field sensed by the TMR con-structed by the Wheatstone full-bridge structure is converted into the resistance change.A low-noise signal processing circuit is used to read the differential output signal.In order to achieve high-precision measurement of this system,the numerical analysis of mechanical parameters and the simulation of the force-field coupling structure are performed in this paper.The spatial magnetic field distribution model is established and theoretical analysis of the magnetic field source is studied.The functional design,noise model establishment and noise calculation of the signal processing circuit are carried out.The electrical signal modulation and magnetic field modulation to suppress 1/f noise which limits the precision of acceleration measurement are explored.The experimental results show that the micro-system achieves a scale factor of 181 mV/g,a resolution of 19 ?g/Hz0.5 at 1 Hz within a range of±2 g.The 1/f noise is sup-pressed about 7.6-fold at 1 Hz through magnetic field modulation.The proposed system provides important reference value and strong technical support for the research on high-precision acceleration measurement technology.