| Silicon micro accelerometer is a typical inertial device of MEMS.It has many advantages,such as small size,light weight,low cost,low power consumption,high reliability,easy digitalization,and can meet the harsh application environment.It has been widely used in aerospace,integrated navigation,aircraft control and other fields.However,as the structure size of silicon micro-accelerometer is greatly reduced,the sensitivity and resolution of the instrument are greatly reduced.The capacitance detection method is greatly affected by parasitic effect,mechanical structure noise,circuit noise,etc.It has basically reached the limit of detection ability,and it is very difficult to further improve the measurement accuracy.Based on this background,this paper studies the application of tunnel magnetoresistive accelerometer,including:（1）Basic theoretical analysis of tunnel magnetoresistive accelerometerFirstly,the working principle of tunnel magnetoresistance sensor is introduced,and the mathematical analysis model of cuboid permanent magnet film is established.Secondly,the acceleration-displacement transformation,displacement-magnetic field transformation and magnetic field-voltage transformation are analyzed,and the theoretical feasibility of open-loop detection of tunnel magnetoresistive accelerometer is demonstrated.Then,the closed-loop design scheme of force feedback for tunnel magnetoresistive accelerometer is studied by introducing differential capacitive torques.（2）Design and analysis of tunnel magnetoresistive accelerometerFirstly,the whole structure of tunnel magnetoresistive accelerometer is proposed and its working principle is analyzed.Subsequently,the microbar structure model of the middle-layer structure is established,and the influence of design parameters of torsion beam and U-beam on displacement sensitivity is analyzed.Finally,the closed-loop measurement and control system of tunnel magnetoresistive accelerometer is studied,and the feasibility of closed-loop control and detection of tunnel magnetoresistive accelerometer is verified.（3）Simulation and analysis of tunnel magnetoresistive accelerometerThe ANSYS Workbench is used to simulate the middle-layer structure of tunnel magnetoresistive accelerometer,including modal simulation,acceleration-displacement simulation,thermal stress simulation and transient impact simulation.Subsequently,the magnetic field sensitivity of tunnel magnetoresistive accelerometer is simulated and analyzed in different installation clearances and different magnetic disk sizes.The feasibility and theoretical correctness of the tunnel magnetoresistive accelerometer are verified by the simulation of the overall structure and magnetic field characteristics.（4）Manufacture and test of tunnel magnetoresistive accelerometerFirstly,the processing technology of DDSOG and the micro-assembly process of tunnel magnetoresistive accelerometer are introduced.Subsequently,the measurement and control circuit of tunnel magnetoresistive accelerometer is fabricated,and the performance of the sensor is tested.The experimental results show that the tunnel magnetoresistive accelerometer can realize linear detection of acceleration signal,the scale factor can reach 18.14 m V/g,the spectrum noise of the tunnel magnetoresistive accelerometer is 86.2 ug/Hz0.5,and the bias stability is 482 ug.The experimental results show that the tunneling magnetoresistive accelerometer designed in this paper is successful and can better realize the function of acceleration detection. |
