Design Of MEMS Inertial Measurement Unit And Research On Its Related Techniques

With the advances of MEMS technologies,the accuracy of MEMS inertial measurement unit(MEMS IMU)has been improved continuously.Considering the advantages of MEMS IMU over its traditional counterparts,such as small size,low power consumption,and low cost,MEMS IMU has been widely adopted in more and more fields.In this paper,a MEMS IMU for an underwater device is developed based on silicon micro-gyroscopes and accelerometers.The temperature compensation technology of silicon micro-gyroscope and the coupling error compensation technology of the MEMS IMU are studied.This article mainly addresses the following issues.(1)The dynamic model and working principle of silicon micro-gyroscopes and accelerometers are analyzed.The source of temperature error of silicon micro-gyroscope which mainly comes from the temperature characteristic of material and circuits is also analyzed and the error classification of MEMS IMU is introduced,which provides a theoretical basis for temperature compensation and error compensation.(2)Based on the analysis of the application environment and engineering requirements of MEMS IMU,the design of the mechanical structure and the analysis of the modal,harmonic and transient response have been carried out.Measurement and control circuits of silicon micro-gyroscope,configuration circuits of accelerometer,signal acquisition and processing circuits have been designed and optimized.The overall framework of software has been designed Programming of signal acquisition,data processing and communication have been done.(3)The influences of temperature on the quality factor,natural frequency,and output of the silicon micro-gyroscope are analyzed.The linear and piecewise linear models are designed for the temperature compensations of the gyroscope at the room temperature and within the full temperature,respectively,which demonstrates a great improvement of the compensation algorithm by comparing the performances before and after compensation and the effects of off-line and real-time compensation.(4)Based on the error analysis of MEMS IMU,the coupling error model of MEMS IMU is established and simplified.The parameters of the coupling matrix and the decoupling matrix are obtained by the calibration experiment.The coupling error of the system is compensated in real-time using FPGA,which obviously reduces the cross-coupling error of the MEMS IMU.(5)The performance of the MEMS IMU was evaluated experimentally.The non-linearity of the scale factor of the gyroscope and the accelerometer are less than 100ppm and 0.25%FS,respectively.The stability of the gyroscope and the accelerometer is less than 4°/h and 200ug at the room temperature and less than 30°/h and 2mg within the full temperature,respectively.The ranges of the gyroscope and the accelerometer are±150°/s and±30g.The power consumption of the MEMS IMU is 1.578W.According to the test results,the accuracy of the MEMS IMU designed in this paper is high enough to satisfy the engineering requirements of the underwater device.